 |
Alberto MUSCIO
Professore Ordinario
Dipartimento di Ingegneria "Enzo Ferrari"
|
Home |
Curriculum(pdf) |
Didattica |
Pubblicazioni
- Contenitore per la conservazione ed il trasporto di bibite o alimenti a temperatura controllata e regolabile.
[Brevetto]
Libbra, Antonio; Muscio, Alberto; L., Tarozzi
abstract
.
- Frigocontenitore portatile a controllo di temperatura
[Brevetto]
Libbra, Antonio; Muscio, Alberto; L., Tarozzi
abstract
.
- Heated and cooled steering wheel
[Brevetto]
L., Menaldo; G., Testa; Muscio, Alberto; S., Soragni
abstract
A steering wheel has a ring portion, spoke portions and a hub portion. The steering wheel is provided with a thermoelectric reversible heat pump to heat or cool a fluid. A closed hydraulic circuit includes a hydraulic pump and at least one duct extending along the ring portion of the steering wheel. The fluid is heated or cooled by the thermoelectric heat pump and is circulated by the hydraulic pump within the ring portion of the steering wheel to heat or cool the ring portion.
2023
- A modified & epsilon;-NTU analytical model for the investigation of counter-flow Maisotsenko-based cooling systems
[Articolo su rivista]
Muscio, A; Cossu, M; Morselli, N; Puglia, M; Pedrazzi, S; Allesina, G
abstract
In this work the e-NTU method has been adapted for the application of a countercurrent evaporative heat exchanger featuring a complex heat transfer surface. The study highlights some challenges related to extending analytical models that were validated on simple geometries and proposes the calibration of the e-NTU method by experimentally measuring the overall heat transfer coefficient (UA) of the heat exchanger. Through a laboratory prototype of the M-cycle, two different operating conditions were investigated (mild and hot-dry climates) which reported almost constant UA values of 14.8 W/K and 16.1 W/K respectively. The obtained results from the model prediction were compared with the experimental data obtaining average errors on the outlet temperatures and on the cooling capacity lower than 1.5% in the case of simulation of hot and dry climate. The positive results allowed to extend the calculation to operating conditions not tested experimentally, highlighting how it is necessary to have NTU over 2-2.5, while the recirculation rate must be kept below 0.4 to make efficient use of the water. The aim is to support the implementation of the technology in full-scale applications, where the M-cycle is used alone or to complement a vapor compression system.
2023
- An experimental protocol using N. commune as pioneer organism to induce bio-deterioration of surfaces: comparison between new and soiled surfaces
[Articolo su rivista]
Santunione, G.; Muscio, A.; Sgarbi, E.
abstract
Biological growth on building surfaces can be responsible for degradation of their aesthetical and functional properties. This is damaging for solar reflective materials (SRM), which are characterised by the ability to reflect solar radiation in the whole wavelength spectrum. SRM represent one of the most efficient countermeasures to the urban heat Island effect. The present study compares different experimental setups to expose SRM samples to laboratory bio-ageing and define which setup is the most repeatable in terms of biodegradation on surfaces.
2023
- Cool Cementitious Materials for a More Sustainable Urban Environment
[Articolo su rivista]
Capone, C; Cacciatore, A; Princigallo, A; Berardi, R; Muscio, A
abstract
The temperature increase in cities called the "urban heat island" (UHI) depends on the local microclimate (e.g., solar irradiation, population, buildings density, industrial activities, traffic, emissions, heat sources) and results not only in increased electricity consumption for indoor cooling but also in decreased outdoor comfort, especially in summer periods or in warm climate zones. As the world's urban population continues to grow, there is an urgency to make buildings more ecoefficient and reduce the impact of cities on climate change and global warming. In this framework, the use of cool concretes can mitigate the UHI and improve energy saving and outdoor comfort: cool concrete roofs and facade cement-based tiles can provide valid solutions to decrease the energy demand for air conditioning in building envelops; moreover, cool concrete paving blocks and pervious pavements can improve urban comfort for outdoor wellbeing. The present work shows the improved solar reflective performance of three cool cementitious solutions compared with traditional ones, with both white and colored surfaces, to fulfill both architectural demand and sustainability issues without any additional post-treatments or after placing steps, such as surface coating. Finally, the study is completed with the durability evaluation of the products' solar reflective performance.
2023
- Ermanno Grinzato: a survey on thermophysical properties assessment
[Articolo su rivista]
Bison, P; Cernuschi, F; Muscio, A
abstract
In this work, the direct contribution and the inspiring activity of Ermanno Grinzato are resumed, focusing on the field of thermophysical properties evaluation. The main branches, followed in more than 30 years of research for the development of the InfraRed thermography technique, are reported and related to the scientific and industrial panorama at the time of their introduction. Those branches witness the spirit of excitement and the foresight of the solutions proposed, developed and adopted in the laboratory of the National Research Council in Padova. That laboratory was in a broad sense the 'Alma Mater' of a generation of researchers that have been working in the InfraRed field.
2023
- Liquid Organic Hydrogen Carriers Applied on Methane-Hydrogen-Fueled Internal Combustion Engines: A Preliminary Analysis of Process Heat Balance
[Articolo su rivista]
Pedrazzi, S; Zucchi, M; Muscio, A; Kaya, Af
abstract
One of the main issues that has limited the use of hydrogen as an energy vector for a long time is its low energy density per unit of volume. Alternative chemical storage methods have been developed in recent years to overcome the limitations associated with compressed or liquified hydrogen storage. One of these is the Liquid Organic Hydrogen Carrier (LOHC), which utilizes organic hydrocarbons that can capture hydrogen (through an exothermic hydrogenation reaction) and release hydrogen (through an endothermic dehydrogenation reaction). In this paper, a 0D model of an internal combustion engine fueled with a mixture of hydrogen and methane was used to investigate whether the enthalpy of the exhaust gases can balance the heat rate required to self-sustain the dehydrogenation stage. Two LOHC+ compounds were considered, namely, Perhydro-dibenzyltoluene and Perhydro-N-Ethylcarbazole. Four different hydrogen-to-methane ratios were considered, assuming an engine maximum brake power ranging from 500 to 6000 RPM. An energy balance was performed, balancing the dehydrogenation heat rate and the exhaust gas cooling heat rate, in order to establish the minimum temperatures of the exhaust gases required to self-sustain the LOHC+ dehydrogenation. We demonstrated that the minimum exhaust temperatures required to self-sustain the process in different running regimes and at different hydrogen-to-methane ratios are lower than literature and experimental exhaust temperatures.
2022
- Analysis of combined low-level indicators for the hot-season performance of roof components
[Articolo su rivista]
Lodi, C.; Muscio, A.; Tartarini, P.; Akbari, H.
abstract
A single performance indicator, the solar transmittance factor (STF), has been proposed in previous works, together with the derived solar transmittance index (STI). It is aimed at evaluating the summer performance of the roofing system and allowing the selection of the most effective mix of surface and mass properties. It is easily calculated from low-level indicators such as U-value, module of periodic thermal transmittance, and solar reflectance. In the present work, the correlation between STF and the cooling energy demand, integrated over a reference period, was studied, as well as the peak of ceiling temperature increase with respect to the indoor temperature, relevant for thermal comfort. In particular, the thermal behavior of different roof types with variable insulation was calculated numerically by TRNSYS 17 for a wide set of locations and environmental conditions. Unlike other commonly used indicators, to which the analysis has been extended, a strong correlation with STF was found for both cooling energy demand and ceiling temperature rise.
2022
- Energy, environmental and feasibility evaluation of tractor-mounted biomass gasifier for flame weeding
[Articolo su rivista]
Morselli, N.; Puglia, M.; Pedrazzi, S.; Muscio, A.; Tartarini, P.; Allesina, G.
abstract
Weed control is an agronomic technique that must be carried out on almost any cultivation, to prevent undesired weeds from competing with crops for nutrients, water, and light and reducing the annual yield. Nowadays, agriculture is experiencing a transition to both sustainable and organic approaches that is driving the increase in non-chemical treatments. Within this framework, thermal methods are gaining attention due to their higher working speed and effectiveness when compared to mechanical ones but thermal devices are still fueled with fossils leading to considerable greenhouse gas emissions. This work investigates the advantages of substituting liquefied petroleum gas (LPG) powered weeder with a portable gasification-based flame weeder fueled with woody biomass. Energy balance, carbon footprint and feasibility aspects are taken into account and the proposed solution is compared with the reference literature of LPG flame weeder. A flame weeder prototype is built starting from the gasification reactor of a commercial micro scale cogeneration unit. The gasifier is then fueled with A2-grade fir pellets and the syngas is burnt in a swirled flare designed for cross-flame weeding in woody crop rows. The biomass-fueled prototype is capable of a thermal flux directed towards the weeds of 208–247 kJ m−2 at a temperature that ranges from 850 to 980 °C. When compared to LPG systems applied to vineyards or orchards, the proposed solution reduces the fuel cost of the 72% and CO2 emissions up to 118% considering the carbon-negative effect added by a 0.653 kg ha−1 of biochar production for each treatment. Results showed a specific fuel consumption of 52.2 kg ha−1 y−1 that can be self-sustained if vineyards prunings are used as fuel.
2022
- Identification of SUHI in Urban Areas by Remote Sensing Data and Mitigation Hypothesis through Solar Reflective Materials
[Articolo su rivista]
Costanzini, S.; Despini, F.; Beltrami, L.; Fabbi, S.; Muscio, A.; Teggi, S.
abstract
The urban heat island (UHI) is an increasingly widespread phenomenon of concern to the wellbeing and the health of populations living in urban environments. The SUHI (Surface UHI) is directly related to UHI and influences its extension and intensity. Satellite images in the thermal infrared spectral region can be used to identify and study the SUHI. In this work, Landsat 8 TIR images were acquired to study the SUHI of a medium-sized municipality of the Po valley in the northern part of Italy. An additional Worldview 3 satellite image was used to classify the study area and retrieve the surface albedo of building roofs. Using the Local Climate Zone approach, existing roof materials were virtually replaced by solar reflective materials, and the mitigation potential of the SUHI and the UHI was quantified. This virtual scenario shows a decrease in the overheating of building roofs with respect to the ambient temperature of up to 33% compared to the current situation in the industrial areas. Focusing on UHI intensity, the air temperature decrease could be up to 0.5◦C.
2022
- Preliminary testing of a simplified methodology for indoor environments evaluation correlated to airborne transmission: The case of a university classroom with vertical low-velocity ventilation
[Relazione in Atti di Convegno]
Puglia, M.; Ottani, F.; Muscio, A.; Cossarizza, A.; Tartarini, P.
abstract
2022
- Replacing batteries with water by an innovative evaporative cooling process for vehicle air conditioning
[Relazione in Atti di Convegno]
Morselli, N.; Cossu, M.; Muscio, A.
abstract
2021
- Analysis of a new index for the thermal performance of horizontal opaque building components in summer
[Articolo su rivista]
Akbari, H.; Lodi, C.; Muscio, A.; Tartarini, P.
abstract
The summer behavior of an opaque building component subjected to the solar cycle depends on the combination of its thermal insulation, inertia, and solar reflectance. To rate the component dynamic behavior while an air conditioning system ensures a steady indoor temperature, a ‘solar transmittance index’ (STI) has been proposed. This is a component-based index calculated from a ‘solar transmittance factor’ (STF). STI takes into account the radiative properties at the outer surface and the thermophysical properties and layer structure of the materials beneath. It correlates the peak heat flux and temperature at the inner surface, relevant to cooling energy and thermal comfort, to the peak solar irradiance. Similar to the well-known ‘solar reflectance index’, STI is determined comparing the STF with two reference values, corresponding to a performance relatively low and very high, respectively. Thanks to its simplicity, the approach may allow defining easy to apply requirements to prevent building overheating, improve indoor comfort, reduce cooling energy demand, and mitigate some fallouts of the urban heat island effect. In this work, focused on roofs above occupied attics, peak heat flux and ceiling temperature are calculated by numerical simulation and compared with STF values for a wide range of roof types.
2021
- Modeling of a hybrid externally fired gas turbine applied to a landfill and green waste management facility
[Articolo su rivista]
Mirandola, S.; Pedrazzi, S.; Allesina, G.; Muscio, A.
abstract
This work discusses the integration of an externally-fired-gas-turbine power plant in a waste disposal facility where municipal solid waste is disposed in a landfill while green waste is pre-treated and selected to be sold as fuel for biomass power plants. The advantages deriving from the in situ green waste biomass conversion using the externally-fired-gas-turbine power plant is simulated using a thermodynamic model implemented in Matlab Simulink. Two different configurations are simulated: a Standard-Externally-Fired-Gas-Turbine (S-EFGT) power plant fuelled with green-waste-derived wood chips and a Hybrid-Externally-Fired-Gas-Turbine (H-EFGT) power plant fuelled with the previous biomass together with landfill gas. Power plant subsystems are modelled through a black box approach. Inputs and outputs of each box are interconnected together to create the overall models. Preliminary simulations were performed for each configuration at the same working fluid flow rate to compare the electrical and thermal efficiency of both power plants. Full scale simulations, considering an existing case study, are then developed. First, energy fluxes and the resulting efficiencies of each configuration are evaluated. Then the techno-economical comparison between the proposed solutions is discussed. Results show a net electrical energy production of 9392 MWh/year with an electrical efficiency of 14.03% for the S-EFGT using about 18,294 ton/year of wood biomass; the H-EFGT energy yield is 25,392 MWh/year with an electrical efficiency of 17.89% using the same biomass consumption and an average flow rate of 1200 Nm3/h of landfill gas. The economic analysis is completed considering the wood biomass sale, the Net Present Value (NPV) analysis showed a payback time of 7 years for the S-EFGT investment and 5.5 years for the H-EFGT one, the NPV value is 1.310.600,00 € and 6.655.792,00 € for the S-EFGT and H-EFGT configuration, respectively.
2021
- Specific and cumulative exhaust gas emissions in micro-scale generators fueled by syngas from biomass gasification
[Articolo su rivista]
Puglia, M.; Morselli, N.; Pedrazzi, S.; Tartarini, P.; Allesina, G.; Muscio, A.
abstract
Climate change, environmental degradation, and biodiversity loss are prompting production systems to shift from a fossil-based economy to a circular bio-based one. In this context, biomass gasification is a promising alternative to fossil fuels that can contribute to power generation in rural communities and remote areas as well as provide a sustainable source of energy for developed countries. In this work, exhaust gas emissions (CO, NOx, and SO2) of two syngas-fueled micro-scale generators were measured. The first system is a commercial biomass gasifier genset, whereas the second is composed of a laboratory-scale gasifier prototype and a portable petrol generator. For this second facility, emissions were measured both running on gasoline and on syngas. The comparison was performed both on the pollutant concentration and on their cumulative amount. This comparison was made possible by calculating the exhaust gas flow by knowing the combustion stoichiom-etry and fuel consumption. The results showed a much lower pollutant concentration running on syngas compared to gasoline. In particular, considering the best configurations, every cubic meter of exhaust gas released running on syngas contains about 20 times less CO and almost one-third less NOx compared to gasoline. Moreover, the cumulative amount of emissions released was also considerably lower due to the lower exhaust gas flow (about 25%) released running on syngas.
2021
- Standard test methods for rating of solar reflectance of built-up surfaces and potential use of satellite remote sensors
[Articolo su rivista]
Costanzini, S.; Ferrari, C.; Despini, F.; Muscio, A.
abstract
More and more attention is being paid to the solar reflectance of built-up surfaces due to its influence on the summer heating of buildings and urban areas and the consequent effects on energy needs for air conditioning, as well as on the peak load of the electric grid. Several standard test methods are available for measuring solar reflectance in the laboratory or in the field, based on different devices and approaches. A convergence of some methods has been achieved by rating programs in the U.S. and, more recently, in Europe and other areas. However, laboratory or field measurements are impractical for characterizing a large number of urban surfaces—whether it is for identifying critical issues, developing policies, or verifying compliance with building requirements. In this regard, satellite remote sensors have recently become available, through which it is possible to estimate the reflectance of roof and pavement surfaces thanks to a spatial resolution that is suitable for identifying and characterizing individual built-up surfaces. In the present paper, the most-used standard test methods for rating of solar reflectance are reviewed. Subsequently, some publicly accessible satellite sensors are examined, through which comparable measurements could be obtained.
2021
- Urban surfaces analysis with remote sensing data for the evaluation of UHI mitigation scenarios
[Articolo su rivista]
Despini, F.; Ferrari, C.; Santunione, G.; Tommasone, S.; Muscio, A.; Teggi, S.
abstract
Considering the new IPCC report and its recent suggestions, it is important to pay serious attention to the Urban Heat Island issue. In this study, satellite images acquired by the Worldview3 sensor (WV3) were processed to classify the different kinds of urban surface and to compute the albedo value for each surface. Then several UHI mitigation scenarios were analyzed, varying selectively the surface albedo by choosing solar reflective materials. Clay tile pitched roofs, dark roofs and parking areas were considered as “modifiable surfaces” and their albedo values were increased on the basis of the literature and of data made available by product manufacturers. For each proposed scenario, the reduction of intensity of the Urban Heat Island effect (ATD), the energy saving brought by lower absorption of air conditioning systems (ΔE) and the consequent cost savings were calculated. All the scenarios proved to be convenient and with a relatively fast return on investment. In particular, two scenarios involving the modification of several surfaces at the same time proved to be the most promising ones from the perspective of a public administration, with significant benefits on the well-being of the population, as well as with similar and relatively short payback periods.
2020
- A simple test method for measurement of the interface thermal resistance of coated and uncoated metal surfaces
[Relazione in Atti di Convegno]
Pedrazzi, Simone; Vergnano, A.; Allesina, G.; Veronesi, Paolo; Leali, F.; Tartarini, P.; Muscio, A.
abstract
Dies for metal casting must often be coated internally to minimize interaction between the surface of the steel die and the melt metal during pouring and solidification. However, the added coating increases the thermal interface resistance during the cooling process and can thus extend the process duration. For example, numerical predictions and experimental results are matched if the interface resistance is even quintupled in the presence of usual interface coating, compared to the uncoated mold. In order to have a reasonable estimate of the interface thermal resistance, an easy to use measurement approach has been tested. This consists of contacting a cold and a hot samples of metals with known thermal properties, one at ambient temperature and the other one much hotter. The temperatures of the two samples, assumed to be uniform in each sample, are measured by thermocouples, and the interface resistance is retrieved from the time evolution pattern of those temperatures during the thermal transient that follows the instant in which the samples have been contacted.
2020
- Effects of soiling and weathering on the albedo of building envelope materials: Lessons learned from natural exposure in two European cities and tuning of a laboratory simulation practice
[Articolo su rivista]
Paolini, R.; Terraneo, G.; Ferrari, C.; Sleiman, M.; Muscio, A.; Metrangolo, P.; Poli, T.; Destaillats, H.; Zinzi, M.; Levinson, R.
abstract
Chemical and physical stress, weathering, organic and inorganic matter deposition, and microbial growth over time, or “aging”, affect the optical-radiative performance of building envelope materials. Natural exposure helps to quantify these effects, but it usually requires several years. Further, the contribution of the different degradation agents cannot be isolated, and results from different campaigns cannot be easily compared because of the variability in the boundary conditions producing aging. Here we present an adaptation of the protocol implemented by ASTM as D7897-18 “Standard Practice for Laboratory Soiling and Weathering of Roofing Materials to Simulate Effects of Natural Exposure on Solar Reflectance and Thermal Emittance”. The aim is to reproduce in the laboratory the changes in albedo (solar reflectance) and thermal emittance experienced by building envelope materials in European urban areas rather than in the United States. We tuned the spraying duration and weathering cycles, and we compared the UV–vis–NIR reflectances of naturally-aged specimens (48 months in Rome and Milan) of roofing and wall finish materials to those exposed to laboratory weathering and soiling. Excluding those materials that show early physical-chemical degradation, the mean absolute deviation between natural and laboratory exposure of roofing products is equal to 0.027 in albedo. This is a lower value than the differences between two natural exposure campaigns at the same site. We clearly defined the limits of application of the protocol, providing an appraisal of the repeatability of natural aging. Moreover, we identified possible improvements in the methodology to conduct both natural and laboratory exposure.
2020
- Il bosco urbano come strategia di mitigazione microclimatica: un caso-studio a Reggio Emilia
[Relazione in Atti di Convegno]
Santunione, Giulia; Muscio, Alberto; Sgarbi, Elisabetta
abstract
2020
- Indirect evaporative cooling by sub-roof forced ventilation to counter extreme heat events
[Articolo su rivista]
Pedrazzi, S.; Allesina, G.; Muscio, A.
abstract
In a pitched ventilated roof, an air stream enters a cavity below the roof surface through openings at the level of the gutters, then it flows up along the roof and is finally discharged through openings along the ridge. The heat brought by the absorbed solar radiation is removed thanks to the flow established by natural ventilation, but only in part because the flow is relatively weak and unstable. As shown in previous work, a stronger and more regular air flow can be ensured by forced ventilation, extracting the air by means of a fan after it has been collected along the ridge by a properly designed manifold. This setup can be further enhanced by humidifying and saturating the air as it enters the cavity, thus significantly lowering the downstream air temperature. An indirect evaporative cooling system is thus obtained, by which an inhabited space under the roof can be cooled through the ceiling while remaining sealed and unaffected by the evaporative process. In this work, the setup is analyzed by a mathematical model and the concept tested by means of a small scale test bed, showing that it can be used to counter extremely hot ambient conditions with a relatively low consumption of liquid water and almost negligible energy need.
2020
- On Bio-Deterioration of Solar Reflective Materials: An Innovative
Experimental Procedure to Accelerate the Ageing Process of Surfaces
[Relazione in Atti di Convegno]
Santunione, Giulia; Ferrari, Chiara; Muscio, Alberto; Sgarbi, Elisabetta
abstract
2020
- Sensor matrix robustness for monitoring the interface pressure between car driver and seat
[Relazione in Atti di Convegno]
Vergnano, A.; Muscio, A.; Leali, F.
abstract
An effective sensor system for monitoring the pressure distribution on a car seat would enable researches on Advanced Driver Assistance Systems (ADAS) and comfort of occupants. However, the irregularities of the seat shape or those of the occupant clothes challenge the robustness of such a sensor system. Moreover, the position identification of bodies of different percentiles by few pressure sensors is difficult. So, a higher resolution pressure pad has been developed. The number of sensors is significantly increased by means of a matrix scan strategy. Tests on the pressure pad with different occupants proves its robustness in scanning the contact area.
2019
- Accelerated biological ageing of solar reflective and aesthetically relevant building materials
[Articolo su rivista]
Santunione, G.; Ferrari, C.; Siligardi, C.; Muscio, A.; Sgarbii, E.
abstract
The properties of building materials relevant to their thermal or aesthetical performance can be seriously influenced by the colonization of external surfaces by microorganisms. Deterioration phenomena due to biological aggression cause the loss of energy performance of solar reflective materials because of the decrease of solar reflectance. Bio-deterioration also affects cultural heritage, damaging the aesthetic appearance and thus the historic value. In order to investigate the consequences of biological aggression in short times, an accelerated test method based on a laboratory-reproducible set-up is proposed. Specific and controlled environmental conditions are chosen to accelerate as much as possible biological growth on building materials. In this regard, a reproducible bio-ageing protocol has been outlined and it allows a set of materials to reach an advanced bio-aged level in a short time (8 weeks or less). This test method is aimed to comparatively evaluate different materials under a given set of ageing conditions. Through surface, microstructural and chemical analysis, the evolution of the materials’ properties after ageing is investigated. Attention is also paid to bacterial and algal growth rate by analysing time-progressive images.
2019
- Easy to implement ventilated sunspace for energy retrofit of condominium buildings with balconies
[Articolo su rivista]
Allesina, Giulio; Ferrari, Chiara; Muscio, Alberto; Pedrazzi, Simone
abstract
Energy retrofit of the facade of condominium buildings may be a difficult task because thermal bridges such as those due to balconies, common elements in the architecture of many countries, are often arduous to correct by added insulation due to several constraints. An alternative retrofit approach is therefore analyzed, easy to implement and relatively inexpensive. It consists in changing a balcony into a ventilated sunspace during the cold season, exploiting solar gains to compensate heat loss. More specifically, transparent plastic roll-up sheets are installed along the balcony perimeter, removable in the hot season, to enclose the volume between two superposed balcony slabs. The obtained sunspace is then used as a pre-heating chamber for a single-flow ventilation system that ensures the air changes required indoors. Heat gain to the indoor environment can thus be increased with respect to a simpler sunspace without ventilation, and possibly modulated along the day by proper control of the flow rate. In this work, the proposed approach and a small-scale physical model are presented. The model will serve to validate analyses aimed to forecast and optimize the performance of ventilated sunspaces built around balconies.
2019
- Effects of abiotic stress induced by a standard mix of atmospheric pollutants in Chlorella
mirabilis (Chlorophyceae)
[Poster]
Santunione, Giulia; Boni, Giulio; Muscio, Alberto; Sgarbi, Elisabetta
abstract
This study evaluates the level of oxidative stress induced by a mix of standard atmospheric pollutants in the green microalga Chlorella mirabilis. Genus Chlorella has been found as one of the most widespread among the phototrophic organisms occurring also in urban context, where it forms biofilms on monumental and building surfaces (1, 2). Aerial and sub-aerial algae are considered suitable bio-indicators to study the effects of pollutants because their species-specific sensitivity may be greater than in higher plants along with faster physiological responses. Furthermore, they are easy to handle and to maintain in controlled conditions (3). For these reasons, Chlorella mirabilis was used in the present study as testing organism to evaluate the response to atmospheric pollutants. With the aim to apply a lot of pollutants without increase the variability of the system, we chose a standard mix of atmospheric pollutants, i.e. ASTM D-7897-2015 (American Society for Testing and Materials International). As result of studies set up on urban surfaces depositions (4,5), used to stress building materials and evaluate their “accelerate ageing” (6), it consists in four kinds of atmospheric particles: soot (carbon), dust, salts, and particulate organic matter, which together represent a dark solution called “soiling mix” (7).
Chlorella mirabilis was firstly grown in a specific culture medium (Bold’s Basal Medium, BBM) in aseptic conditions at 23 °C, under 14 h photoperiod. To evaluate the effects of pollutants, algal cultures were carried out at the same time in a new medium (BBM-SM) obtained by mixing “soiling mix” with BBM (1:5 v/v).
Stress level in algae growing inside BBM-SM was assessed through the quantitative determination of photosynthetic pigments (Chlorophyll a, b and carotenoids) and malondialdehyde (MDA), this last considered as marker of lipid peroxidation. The extraction of photosynthetic pigments and oxidative metabolites was performed according with the methods of Lichenthaler (8) and Heath and Packer (9), respectively. Cell density was monitored during the experimental tests and the algal growth curve was described in both cultures conditions, after 15 day of algal growth.
Results of repeated tests on algae cultures stressed by pollutants underline an increase over 60% of MDA compared with control cultures, highlighting the occurrence of oxidative stress. At the same time the concentration of chlorophyll a and b and carotenoids decreases over 60%, 20% and 70%, respectively. Observation under light microscope shows shape and colour changes in algal cells during their growth in BBM-SM. Nevertheless, C. mirabilis proved to be able to survive in critical environmental conditions characterized by high concentration of pollutants and dark particulate. These results may represent an important first step to use this species in studies on cell response to different stress factors and moreover may have interesting effects on many fields of applied plant biology.
2019
- Evaluation of heat-wrap thermal transient behavior: The development of an experimental test procedure
[Relazione in Atti di Convegno]
Santangelo, Paolo Emilio; Santunione, Giulia; Muscio, Alberto
abstract
Heat wraps represent the most used thermotherapy methods over the last 2 decades as a self-administered practice for pain relief. A deep knowledge regarding their performance has become a priority within healthcare industry. However, the majority of the available studies have been focused on in vivo clinical performance, whereas a standardized, quantitative approach to evaluate and compare the various heat-wrap types against each other is lacking. An experimental methodology is proposed to carry out a comparative assessment between heat wraps in terms of their transient thermal behavior. A simple setup was developed to measure wrap/substrate interface temperature trend. The approach was validated by a preliminary infrared-thermography assessment and statistical analysis on the extensive dataset acquired on commercial heat-wrap types for low-back and neck pain relief. The heat-release trend was found to be qualitatively similar over all the investigated types, consisting of rapid growth, stationary phase, decay and end of the reactions. A set of parameters is also proposed to summarize heat-wrap thermal performance.
2019
- Experimental methodology for quantitative assessment of heat-wrap thermal transient behavior
[Articolo su rivista]
Santangelo, Paolo Emilio; Santunione, Giulia; Muscio, Alberto
abstract
Among the numerous thermotherapy methods, heat wraps have been largely used over the last 2 decades as a self-administered practice for pain relief. Therefore, understanding their performance has become instrumental within the healthcare industry. However, the majority of the available studies have been focused on in vivo clinical performance, whereas a standardized, quantitative approach to evaluate and compare the various heat-wrap types against each other is lacking. An experimental methodology is proposed to carry out a comparative assessment between heat wraps in terms of their transient thermal behavior. A simple setup was developed to measure wrap/substrate interface temperature trend. The approach was validated by a preliminary infrared-thermography assessment and statistical analysis on the extensive dataset acquired on commercial heat-wrap types for low-back and neck pain relief. The heat-release trend was found to be qualitatively similar over all the investigated types, consisting of rapid growth, stationary phase, decay and end of the reactions. A set of parameters is also proposed to sum-marize heat-wrap thermal performance.
2019
- Maison CBET - A comprehensive full scale test bench for comfort and energy analysis of buildings
[Relazione in Atti di Convegno]
Follain, V.; Goldoni, M.; Muscio, A.; Rossetti, M.
abstract
An innovative test bench has been developed in the framework of the Project CBET - Cross Border Energy Trainings, funded by the Interreg ALCOTRA 2014-2020 Program of the European Union and aimed to increase the educational, training and professional skills on energy efficiency, renewable energy sources and green buildings in the cross-border area between Italy and France. The test bench, called Maison CBET, consists of a transportable standard container modified in a heated, ventilated and air-conditioned habitable office. The opaque and glazed components of the thermal envelope can be easily modified from uninsulated to well insulated, with a wide range of options, as well as shielded against solar radiation. A complete HVAC system is also installed. This is based on electric devices that can be switched on selectively and are powered by separate power lines, continuously monitored by a real time data acquisition system. Weather data and internal comfort parameters are contemporarily monitored. This paper presents a prototype of the test bench that is currently under construction and will be installed in the campus of the Lycée Léonard de Vinci at Antibes, France.
2019
- Smart use of mechanical ventilation for energy retrofit of residential dwellings
[Relazione in Atti di Convegno]
Pedrazzi, S.; Ferrari, C.; Allesina, G.; Muscio, A.
abstract
Residential buildings of Italy built during the last century usually show very poor energy performance. The only retrofit action widely implemented on their envelope is substitution of windows. These are very seldom coupled with mechanical ventilation, however, so their high air tightness induces serious problems of moisture condensation and mold formation-unless they are left open and their usefulness nullified. In this work, a smart combination is simulated of single flow mechanical ventilation, in itself essential to control indoor air quality and ventilation heat loss, with a relatively inexpensive sunspace built on an existing balcony, aimed to behave as a preheating chamber of the inlet cold air in winter. Moreover, mechanical ventilation is combined with an electric heat pump for hot water production, in which the outlet air flow of warm exhaust air is introduced to improve the coefficient of performance of the heat pump in the cold seasons. Energy savings allowed by such smart yet simple combination of existing technologies are discussed.
2019
- Thermal conductivity measurement of insulating innovative building materials by hot plate and heat flow meter devices: A Round Robin Test
[Articolo su rivista]
Baldinelli, Giorgio; Bianchi, Francesco; Gendelis, Stanislavs; Jakovics, Andris; Morini, Gian Luca; Falcioni, Stefania; Fantucci, Stefano; Serra, Valentina; Navacerrada, M. A.; Díaz, C.; Libbra, Antonio; Muscio, Alberto; Asdrubali, Francesco
abstract
The characterization of thermal insulation properties of construction materials represents a fundamental step on the building insulation assessment. In recent years innovative materials have been introduced in the market to fulfill the continuously growing requirements of energy saving and sustainability, and their performance is not so reliable and mature as it happens for traditional insulators. The work presents a Round Robin Test realised among six European laboratories hosting hot plates devices to measure the thermal conductivity of four different materials: aerogel, vacuum insulation panels, polystyrene and birch wood fibre insulation boards. After the definition of the common measurement protocol, the tests campaign was executed and the results were checked with a consistency analysis. Data showed that the hot plate apparatuses result suitable for the measurement of the tested innovative materials, both in terms of absolute values retrieved and repeatability. The reproducibility is satisfactory as well, except for vacuum insulation panels, the most insulating samples, which present values of standard deviations quite high, at least in relative terms, so showing that the thermal properties of high performance materials must be assessed with particular care.
2019
- Ventilated pitched roof with forced ventilation and flow homogenizer device: Testing and performance assessment
[Relazione in Atti di Convegno]
Ferrari, C.; Muscio, A.
abstract
Ventilated tile roofs are common objects in the construction sector of Italy. A preferred type is characterized by a ventilated air space between the upper tile layer and the roof structure below. The air enters through openings at the gutters level, flows up below sheathing in the air space along the pitch and is finally discharged through openings along the ridge. This setup, which leaves the room below the roof sealed and habitable, allows removing the heat brought by the absorbed solar radiation thanks to the flow that is established by natural ventilation in the air space. However, its actual performance is often weak and also unpredictable due to continuously changing buoyancy forces. Nonetheless, a permanent and adequate flow can be ensured even through a relatively thin air space and for whichever irradiance and wind conditions by forced ventilation: a properly designed fan can provide the desired flow rate by extracting the air after this is collected along the ridge by a manifold. A thorough design and manufacturing of the manifold is needed, however, to avoid a highly inhomogeneous flow, which would follow the easiest path and leave most of the pitch practically unventilated. As an alternative, a throttling shutter parallel to the ridge has been proposed to progressively choke the flow entering the manifold through parallel climbing ducts as the fan is approached, possibly allowing onsite adjustment after installation. In this work the solution, developed by means of a small scale test bed, is illustrated in details and some methods to assess the performance are presented.
2018
- A calibration methodology for building dynamic models based on data collected through survey and billings
[Articolo su rivista]
Allesina, G.; Mussatti, E.; Ferrari, F.; Muscio, A.
abstract
A correct dynamic building modeling requires a proper definition of all the parameters that can affect the model outputs. While a preliminary survey will lead to a precise design of the building envelope, other parameters, such as the temperature set-point and the air leakage, are difficult to accurately evaluate, thus introducing errors in the model. Furthermore electrical and thermal consumption invoices are based on monthly records while simulations tools use hours or even more detailed time steps. For all these reasons, the present work is aimed at the definition of a calibration process based on survey, billings and dynamic modeling that takes into account the operator-dependent parameters. The innovative idea behind this calibration process consists of the comparison of the real and simulated energy signatures. 176 + 40 simulations were run in order to find the set of parameters that most accurately overlap the simulated and real energy signatures leading to the calibration of the model. The case study is a retail superstore of 3544 m2floor area built in central northern Italy. Results demonstrate the validity of the approach proposed showing a calibrated signature with about 1% discrepancies from the real case one. The approach can be extended to different simulation software since the main advantage of the energy signature is to simplify consumption outputs interpretation even in case of complex buildings. A further innovative consequence of the methodology proposed is its capability to promptly identify inefficiencies in the building subsystems, i.e. the HVAC control, thus leading to a fast correction of the root cause without the implementation of complex and expensive monitoring devices.
2018
- Are Nano-Composite Coatings the Key for Photovoltaic Panel Self-Maintenance: An Experimental Evaluation
[Articolo su rivista]
Pedrazzi, Simone; Allesina, Giulio; Muscio, Alberto
abstract
This article shows the influence of an anti-fouling nano-coating on the electrical energy produced by a string of photovoltaic modules. The coating effect was evaluated comparing the energy produced by two strings of the same PV power plant: one of them was cleaned and the other was cleaned and treated with the coating before the monitoring campaign. The PV plant is located in Modena, north of Italy. A first monitoring campaign of nine days after the treatment shows that the treatment increases the energy production on the PV arrays by about 1.82%. Results indicate that the increase is higher during sunny days with respect to cloudy days. A second monitoring campaign of the same length, but five months later, shows that the energy gain decreases from 1.82% to 0.69% due to the aging of the coating, which is guaranteed for one year by the manufacturer. A technical-economical analysis demonstrates that at the moment the yearly economic gain is 0.43 € per square meter of panel and the cost of the treatment is about 1 € per square meter. However, large scale diffusion can reduce the production cost and thus increase the affordability of the coating.
2018
- On field evaluation of solar reflectance: how the 1918A masks affect the albedo measurements
[Relazione in Atti di Convegno]
Santunione, Giulia; Ferrari, Chiara; Muscio, Alberto
abstract
2018
- PROGRESS IN URBAN GREENERY MITIGATION SCIENCE – ASSESSMENT METHODOLOGIES ADVANCED TECHNOLOGIES AND IMPACT ON CITIES
[Articolo su rivista]
Santamouris, Mat; Ban-Weiss, George; Osmond, Paul; Paolini, Riccardo; Synnefa, Afroditi; Cartalis, Constantinos; Muscio, Alberto; Zinzi, Michele; Morakinyo, Tobi Eniolu; Ng, Edward; Tan, Zheng; Takebayashi, Hideki; Sailor, David; Crank, P.; Taha, Haider; Pisello, Anna Laura; Rossi, Federico; Zhang, Jiong; Kolokotsa, Denia
abstract
Urban greenery is a natural solution to cool cities and provide comfort, clean air and significant social, health and economic benefits. This paper aims to present the latest progress on the field of greenery urban mitigation techniques including aspects related to the theoretical and experimental assessment of the greenery cooling potential, the impact on urban vegetation on energy, health and comfort and the acquired knowledge on the best integration of the various types of greenery in the urban frame. Also to present the recent knowledge on the impact of climate change on the cooling performance of urban vegetation and investigate and analyse possible technological solutions to face the impact of high ambient temperatures.
2018
- The solar reflectance index as a tool to forecast the heat released to the urban environment: Potentiality and assessment issues
[Articolo su rivista]
Muscio, Alberto
abstract
Overheating of buildings and urban areas is a more and more severe issue in view of global warming combined with increasing urbanization. The thermal behavior of urban surfaces in the hot seasons is the result of a complex balance of construction and environmental parameters such as insulation level, thermal mass, shielding, and solar reflective capability on one side, and ambient conditions on the other side. Regulations makers and the construction industry have favored the use of parameters that allow the forecasting of the interaction between different material properties without the need for complex analyses. Among these, the solar reflectance index (SRI) takes into account solar reflectance and thermal emittance to predict the thermal behavior of a surface subjected to solar radiation through a physically rigorous mathematical procedure that considers assigned air and sky temperatures, peak solar irradiance, and wind velocity. The correlation of SRI with the heat released to the urban environment is analyzed in this paper, as well as the sensitivity of its calculation procedure to variation of the input parameters, as possibly induced by the measurement methods used or by the material ageing.
2017
- An index for the overall performance of opaque building elements subjected to solar radiation
[Articolo su rivista]
Muscio, Alberto; Akbari, Hashem
abstract
The thermal behavior of an external opaque building element depends on the combination of several physical characteristics related to insulation level, thermal inertia, external radiative properties. Concerning the insulation level, parameters like the R-value and its inverse, the U-value or thermal transmittance, are commonly considered in building codes, but they are defined with reference to steady-state conditions and cannot describe the behavior of the element when it is subjected to the cycle of solar radiation. On the other hand, parameters like periodic thermal transmittance, decrement factor and time shift represent the dynamic response of the element resulting from its thermal inertia, so they are often considered but do not include the capability of returning solar energy to the atmosphere. In this regard, a few additional parameters are relevant such as solar reflectance and thermal emittance of the external surface, which are unrelated to both insulation and inertia.In order to rate the overall dynamic behavior of an external opaque building element subjected to the cycle of solar radiation and constant indoor temperature, a "solar transmittance index" (STI) is proposed. STI includes in a single performance parameters the effects of both the radiative properties of the external surface and the thermo-physical properties of the materials under the surface. The utilization of such single performance parameter may be greatly helpful in defining requirements and policies to prevent building overheating, reduce cooling energy demand and mitigate the fallouts of the urban heat island effect.
2017
- Cool roofs with high solar reflectance for the welfare of dairy farming animals
[Relazione in Atti di Convegno]
Santunione, Giulia; Libbra, Antonio; Muscio, Alberto
abstract
Ensuring livestock welfare in dairy farming promotes the production capacity of the animals in terms of both quantity and quality. In welfare conditions, the animals can produce at their full potential. For the dairy cattle the most debilitating period of the year is summer, when the stress arising from overheating induces physiological alterations that compromise the animals’ productivity. In this study, the summer discomfort of dairy animals is primarily quantified and the production loss is quantified versus the Temperature Humidity Index (THI), which correlates the values of temperature and relative humidity to the thermal stress. In order to reduce or eliminate such thermal stress, it is then proposed to coat the roof of the stables with a paint having high solar reflectance and thermal emittance, that is a cool roof product. This type of roofing solution can considerably limit the overheating of stables caused by solar radiation, thus providing a positive impact on the animals’ welfare and improving significantly their productivity in summer.
2017
- How accelerated biological aging can affect solar reflective polymeric based building materials
[Relazione in Atti di Convegno]
Ferrari, C.; Santunione, G.; Libbra, A.; Muscio, A.; Sgarbi, E.
abstract
Among the main issues concerning building materials, in particular outdoor ones, one can identify the colonization by microorganisms referred to as biological aggression. This can affect not only the aesthetical aspect but also the thermal performance of solar reflective materials. In order to improve the reliability of tests aimed to assess the resistance to biological aggression and contextually reduce the test duration, an accelerated test method has been developed. It is based on a lab reproducible setup where specific and controlled environmental and boundary conditions are imposed to accelerate as much as possible biological growth on building materials. Due to their widespread use, polymeric materials have been selected for the present analysis, in the aim of reaching an advanced bio-aged level in a relatively short time (8 weeks or less) and at the same time comparatively evaluate different materials under a given set of ageing conditions. Surface properties before, during and after ageing have been investigated by surface, microstructural and chemical analyses, as well as by examination of time progressive images to assess bacterial and algal growth rate.
2017
- Improvement of thermal comfort and energy efficiency in historical and monumental buildings by means of localized heating based on non-invasive electric radiant panels
[Articolo su rivista]
Lodi, Chiara; Magli, Susanna; Contini, Francesco Maria; Muscio, Alberto; Tartarini, Paolo
abstract
Energy efficiency and thermal comfort in historic buildings are very often hampered by preservation
needs. This issue is particularly relevant for historical and monumental buildings, which currently represent
a large part of the historic buildings stock in Europe. For such protected buildings most of the available
retrofitting solutions are not feasible and alternatives have to be investigated to guarantee their
usability potential. The purpose of this study is therefore to present a methodology to evaluate the potential
of electric radiant panels as retrofitting solutions for historical and monumental buildings, focusing
on thermal comfort and energy saving potential when compared with conventional fossil-fuel-based
heating systems. In fact, the non-invasiveness and flexibility of electrical panels make them one of the
few feasible solutions for protected buildings.
An original methodology is developed to evaluate the performance of such localized heating systems;
the methodology is based on a dynamic simulation model, calibrated with temperature measurements,
which takes into account the geometry and technical characteristics of electrical radiant panels and
allows different control strategies to be compared. The methodology is applied to a relevant Italian historical
building. The results show that the panels, despite their well-known low-exergy efficiency, may
become a viable and attractive solution for historical buildings without undermining their preservation
requirements. Apart from significantly increasing thermal comfort, electric radiant panels may also allow
annual heating energy savings up to 70% for the selected building.
2017
- MISURA E OTTIMIZZAZIONE DELLA RIFLETTANZA SOLARE DI TETTI VERDI
[Relazione in Atti di Convegno]
Santunione, Giulia; Ferrari, Chiara; Libbra, Antonio; Sgarbi, Elisabetta; Muscio, Alberto
abstract
Tra le diverse soluzioni finalizzate alla sostenibilità ambientale e al contenimento del fabbisogno energetico estivo degli edifici vi sono i cosiddetti green roof, o tetti verdi. La loro efficacia dipende dalla tipologia di vegetazione che li costituisce, in relazione alla quale esistono ampie le possibilità di ottimizzazione in virtù della vastissima biodiversità vegetale disponibile. In questo lavoro, con l’intento di migliorare l’efficienza energetica dei tetti verdi attraverso l’aumento della loro albedo, si sono analizzate sperimentalmente le proprietà radiative di una specie erbacea con elevate potenzialità, la Stachys byzantina
2017
- University energy planning for reducing energy consumption and GHG emissions: The case study of a university campus in Italy
[Articolo su rivista]
Lodi, Chiara; Malaguti, Vania; Contini, Francesco Maria; Sala, Luigi; Muscio, Alberto; Tartarini, Paolo
abstract
Reduction of energy consumption in educational buildings, and primarily in University buildings, is nowadays a relevant issue. The evaluation of the energy performance of these buildings is complex due to the variability in their construction age and their intermittent and wide variety of uses. In addition, these buildings are often characterized by a scarce availability of energy end use data, which makes challenging to benchmark energy performance and to inform energy policy decisions. To tackle this problem, this paper explores the use of simple indicators linking low-frequency available energy consumption data to variables measuring building characteristics and weather conditions. The use of such indicators is accompanied by detailed ad-hoc energy audits, including activities in the area of building management systems and dynamic energy simulation. The case study chosen is the Italian University of Modena and Reggio Emilia, which recently developed a Sustainability Plan targeting reductions in GHG emissions to 2020 and identified a framework for investment over the next 5 years to meet University targets. The results of the study shows that simple performance indicators can provide a first insight into the buildings energy performance and identify critical buildings that require detailed analysis. The results of the energy audits support the decision of actions to reduce heating and cooling energy consumption while maintaining acceptable thermal comfort for occupants.
2016
- A composite cool colored tile for sloped roofs with high 'equivalent' solar reflectance
[Articolo su rivista]
Ferrari, Chiara; Libbra, Antonio; Cernuschi, Federico Maria; De Maria, Letizia; Marchionna, Stefano; Barozzi, Matteo; Siligardi, Cristina; Muscio, Alberto
abstract
Mediterranean cities are characterized by sloped roofs with ceramic tiles of traditional colors such as brick red in different tones. Their solar reflectance is generally low and can cause overheating of the building due to solar gains during the hot season. In this work, an innovative approach is tested to achieve roof tiles with high capacity of rejecting solar radiation. It consists of using a cool-colored tile with relatively high solar reflectance, combined with a thin insulating layer attached below the tile and made of a silica-gel super-insulating material. An aluminum foil with very low thermal emittance is also applied below the insulating layer. Along the perimeter of each tile, line brushes are attached in order to enclose an almost sealed air space between the aluminum foil and the roof slab below when the tiles are supported on wooden battens. Composite tiles like that outlined here can provide a strong increase of roof thermal resistance, helpful to control either heat loss in winter, or building overheating in summer. They can be installed onto an existing roof, for instance the sloped tile roof of a historical or traditional building, with no need to modify the roof height and structure.
2016
- Correlation between remote sensing data and ground based measurements for solar reflectance retrieving
[Articolo su rivista]
Despini, Francesca; Ferrari, Chiara; Bigi, Alessandro; Libbra, Antonio; Teggi, Sergio; Muscio, Alberto; Ghermandi, Grazia
abstract
Surface and atmospheric modifications due to urbanization generally lead to the urban heat island effect (UHI). This phenomenon is an issue of growing interest and has long been studied by ground based observation. With the advent of remote sensing technologies, observation of UHIs became possible with airborne and spaceborne sensors. Remote sensing data allow urban surfaces characterization to study UHI mitigation methodologies such as the application of cool roofs and cool colors.
In this study remote sensing data have been used first to identify urban surfaces and then to retrieve the solar reflectance value of these surfaces.
The first area of interest is the city of Modena in the Emilia Romagna region (Italy). On this area orthorectified images by an airborne sensor are used. Available images do not allow to directly obtain the solar reflectance value. Therefore it has been investigated a correlation between satellite remote sensing data and ground based measurements.
The solar reflectance was obtained for all urban surfaces of interest such as roofs and pavements. In this way it was possible to assess the real situation and to hypothesize achievable improvements in the solar reflectance of several urban surfaces aimed at improving thermal comfort and energy efficiency of buildings.
2016
- Coupling of solar reflective cool roofing solutions with sub-surface phase change materials (PCM) to avoid condensation and biological growth
[Articolo su rivista]
Muscio, Alberto
abstract
Cool roofs are effective solutions to counter the overheating of building roofs, inhabited spaces below and urban areas in which buildings are located thanks to their capability of reflecting solar radiation. Nonetheless, the relatively low surface temperatures that they induce can cause condensation of humidity and leave the surface wetted for large part of the day, thus promoting the growth of bacteria, algae and other biological fouling; this can cause a quick decay of the solar reflective performance. Biological growth is countered by surface treatments, which however may be toxic and forbidden in many countries and may also vanish quickly. It can also be countered by lowering the thermal emittance and thus decreasing heat transfer by infrared radiation to the sky and the consequent night undercooling, but this can decrease the performance of cool roofs. An alternative approach, which is analyzed in this work, is to embed in the first layer below the cool roof surface a phase change material (PCM) that absorbs heat during the daytime and then releases it in the nighttime. This can increase the minimum surface temperatures, thus reducing the occurrence humidity condensation and, with this, the biological growth. In this work, preliminary results on the coupling of a cool roof surface with a PCM sublayer are presented, being obtained by theoretical investigation on commercial materials and taking into account the time evolution pattern of the environmental conditions.
2016
- Development of a Solar-reflective Ceramic Tile Ready for Industrialization
[Relazione in Atti di Convegno]
Ferrari, Chiara; Muscio, Alberto; Siligardi, Cristina
abstract
Solar-reflective surfaces represent an effective countermeasure to UHI. The market of "cool" materials is dominated by polymeric solutions which, under UV exposure, are damaged. On the other hand, an increasing attention was paid recently to ceramic-based solar-reflective surfaces, characterized by very long lifespan. A ceramic tile is typically made by a three layers structure: substrate-engobe-glaze. This structure has been exploited to develop a cool ceramic tile that can be produced in the same production facilities of common products to create a whole tile by merging technological results and industrial production needs, to achieve a compromise between performance and costs.
2016
- Dynamic analysis of the heat released by tertiary buildings and the effects of urban heat island mitigation strategies
[Articolo su rivista]
Magli, Susanna; Lodi, Chiara; Contini, Francesco Maria; Muscio, Alberto; Tartarini, Paolo
abstract
This study presents a comprehensive approach for calculating buildings' energy contribution to the formation of urban heat island (UHI). For this purpose, the heat released by building envelope and HVAC system has been taken into account, while longwave radiation to the sky has been excluded from the calculation, as it is not so relevant to the UHI effect. Several strategies to minimize the UHI phenomenon and their effects on the heat released have been considered along the whole-year period. An existing educational building has been selected as case study. The selected building is considered representative for a wide range of tertiary buildings with an intermittent operation mode. Results have been obtained by dynamic simulation models, which have been validated with measured indoor air temperature data. Despite a moderate reduction of the energy contribution to the UHI effect during winter, which is commonly considered unfavorable, the effectiveness of cool coating application in reducing the heat released during summer has been clearly demonstrated. On the other hand, it was found that a higher level of envelope insulation is not yielding a significant reduction of the heat released, especially during summer.
2016
- Local climate change and urban heat island mitigation techniques - The state of the art
[Articolo su rivista]
Akbari, Hashem; Cartalis, Constantinos; Kolokotsa, Denia; Muscio, Alberto; Pisello, Anna Laura; Rossi, Federico; Santamouris, Matheos; Synnefa, Afroditi; Wong, Nyuk Hien; Zinzi, Michele
abstract
Increase of the ambient air temperature in cities caused by the urban heat island phenomenon has a seri- ous impact on the economic and social system of cities. to counterbalance the consequences of the increased urban temperatures important research has been carried out resulting in the development of efficient mitigation technologies. the present paper aims to present the state of the art in terms of local climate change and urban heat island mitigation techniques. In particular, developments in the field on highly reflective materials, cool and green roofs, cool pavements, urban green and of other mitigation technologies are presented in detail, while examples of implemented projects are given.
2016
- Robotic implementation of the slide method for measurement of the thermal emissivity of building elements
[Articolo su rivista]
Pini, Fabio; Ferrari, Chiara; Libbra, Antonio; Leali, Francesco; Muscio, Alberto
abstract
A significant interest exists in measuring the thermal emissivity of building surfaces since high values combined with high solar reflectance allow rejecting solar energy absorbed by irradiated surfaces, whereas intermediate or low values permit to limit condensation of humidity, heat loss to the sky, or heat transfer through airspaces. The most used measurement method is probably that described by the ASTM C1371 Standard, which correlates the thermal emissivity to the radiative heat flux exchanged in the infrared between the sample surface, kept at ambient temperature, and the bottom surface of a hot emissometer head. With samples showing a low thermal conductivity, the 'slide method' modification is generally used: the hot head is allowed to slide above the sample in order to prevent this from warming up. The slide movement, however, is carried out by hand and time is needed to achieve a stabilized output, therefore the measurement may be time-consuming and also affected by the operator. In order to solve both problems, an automated approach is proposed here, in which the head is moved by the arm of a robot. This manages either the slide movement or the calibration with reference samples, interacting with a computerized data acquisition system that monitors the emissometer output.
2016
- Un nuovo approccio per lo studio del deterioramento delle proprietà superficiali: l’invecchiamento biologico accelerato
[Relazione in Atti di Convegno]
Santunione, Giulia; Ferrari, Chiara; Libbra, Antonio; Sgarbi, Elisabetta; Siligardi, Cristina; Muscio, Alberto
abstract
La colonizzazione delle superfici esterne da parte dei microorganismi, può influenzare seriamente le proprietà dei materiali edili. Il fenomeno del deterioramento, dovuto all’aggressione biologica causa infatti perdita nelle performance energetiche dei materiali “cool” a causa di un decadimento della riflettanza solare. Inoltre, i problemi relativi al bio-deterioramento affligono anche i monumenti del patrimonio artistico, danneggiando sia il loro valore estetico, sia il loro valoro storico-culturale. Al fine di investigare quali sono le conseguenze dell’aggressione biologica sui materiali edili in tempi ristretti, questo lavoro mostra un metodo di prova di invecchiamento accelerato e riproducibile in laboratorio.
Sono state accuratamente scelte specifiche condizioni ambientali per accelerare il più possibile la crescita biologica sui materiali. È stato messo a punto un protocollo di invecchiamento biologico ben dettagliato e riproducibile al fine di ottenere un buon livello di aggressione biologica ai set di materiali selezionati in un breve lasso di tempo (8 settimane). Si è volute inoltre testare tramite lo stesso protocollo di bio-deterioramento accelerato, l’efficacia dell’azione protettiva di alcuni prodotti alghicidi in commercio. Tale metodo permette di valutare e confrontare le performance di diversi materiali sottoposti alle medesime condizioni ambientali. Grazie alle caratterizzazioni delle superfici questo studio definisce come le proprietà dei materiali cambiano nel post invecchiamento attraverso analisi chimiche fisiche e strutturali, la crescita algale è stata inoltre monitorata attraverso periodiche acquisizioni di immagini analizzate con software specifici.
2015
- Analysis of the urban heat island effects on building energy consumption
[Articolo su rivista]
Magli, Susanna; Lodi, Chiara; Lombroso, Luca; Muscio, Alberto; Teggi, Sergio
abstract
Urban areas usually experience higher temperatures when compared to their rural surroundings. Several studies underlined that specific urban conditions are strictly connected with the Urban heat island (UHI) phenomenon, which consists in the environmental overheating related to anthropic activities. As a matter of fact, urban areas, characterized by massive constructions that reduce local vegetation coverage, are subject to the absorption of a great amount of solar radiation (short wave) which is only partially released into the atmosphere by radiation in the thermal infrared (long wave). On the contrary, green areas and rural environments in general show a reduced UHI effect, that is lower air temperatures, due to evapo-transpiration fluxes. Several studies demonstrate that urban microclimate affects buildings’ energy consumption and calculations based on typical meteorological year could misestimate their actual energy consumption. In this study, two different sets of meteorological data are used for the calculation of the heating and cooling energy needs of an existing university building. The building is modeled using TRNSYS v.17 software. The first set of data was collected by a weather station located in the city center of Modena, while the second set of data was collected by another station, located in the surrounding area of the city, near to the studied building. The influence of the different meteorological situations described by the two weather stations are analyzed and assumed to be representative of the UHI effect. Furthermore, the effects of UHI mitigation strategies on the building energy needs are evaluated and discussed.
2015
- Cooling Heat Islands
[Articolo su rivista]
Akbari, Hashem; Muscio, Alberto
abstract
According to the United Nation report “World Urbanization Prospects”, 54% (about 3.9 billion) of the world’s population residing in urban areas in 2014. The urban population is expected to grow to 66% (about 6.3 billion) by 2050. In addition to encountering many challenges of global climate change, urban inhabitants face many problems associated with urban heat islands (UHI) such as higher outdoor summertime temperatures, higher urban air pollutions, higher demands for air conditioning, and higher heat stress-related mortalities, to name a few. Although the migration to urban areas is caused by macro and global economic drives and little can be done to reverse the trend in the short-term, the policy makers can design effective urban growth policies to mitigate the detrimental effects of UHIs. The Third International Conference on Countermeasures to Urban Heat Island held in Venice, Italy in October 2014 brought together the community of scholars and policy makers to focus on development of effective countermeasures to UHIs.
Over 160 papers discussing advances in both policy and science of UHI countermeasures were presented in the Venice conference. A group of high-quality papers focusing on issues related to the effect of UHI on buildings energy use are published in a special issue of Energy and Buildings. Fifteen other high-quality papers related to urban climate are collected in this special issue of Urban Climate. Papers included in this special issue address:
Quantification and monitoring of urban heat islands and effects on urban climate
Sismanidis; Keramitsoglou, and Kiranoudis discuss a satellite-based system for continuous monitoring of surface UHIs
Kaloustian and Diab present the results of an analysis on the effects of urbanization on the UHI in Beirut
Polydoros and Cartalis assess the impact of urban expansion to the state of thermal environment of peri-urban areas using indices
Rasul, Balzter, and Smith analyze the spatial variation of the daytime surface urban cool island during the dry season in Erbil, Iraqi Kurdistan, from Landsat 8
Analysis of the effects of urban-scale countermeasure technologies
Noro and Lazzarin present the results of simulation analysis of the effect of UHI mitigation strategies in Padua, Italy
Ruiz, Sosa, Correa, and Cantón discuss suitable configurations for forested urban canyons to mitigate the UHI in the city of Mendoza, Argentina
Musy, Malys, Morille, and Inard evaluate the use of SOLENE-microclimate model to assess adaptation strategies at the district scale
Duarte, Shinzato, Gusson, and Alves evaluate the impact of vegetation on urban microclimate to counterbalance built density in a subtropical changing climate
Yoshida, Hisabayashi, Kashihara, Kinoshita, and Hashida evaluate the effect of tree canopy on urban thermal environment
Lobaccaro, and Acero present a comparative analysis of green actions to improve outdoor thermal comfort inside typical urban street canyons
Botham-Myint, Recktenwald, and Sailor discuss the thermal footprint effect of rooftop urban cooling strategies
Simplified methods to quantify the effect of UHI countermeasure
Touchaei and Akbari discuss a method to evaluate the seasonal effect of increasing albedo on urban climate and energy
Pomerantz, Rosado and Levinson outline a simple tool for estimating city-wide annual electrical energy savings from cooler surfaces
Innovative methods to improve urban outdoor thermal comfort
Kleerekoper, van dan Dobbelsteen, van den Ham, Hordijk, and Martin explore a new climate adaptation technique by proposing colored façades to create drafts in urban settings
Castaldo presents results of a thermal-energy analysis of natural “cool” stone aggregates as passive cooling and global warming mitigation technique
Editors of this special issue, Cooling Heat Islands, hop
2015
- Design of a cool color glaze for solar reflective tile application
[Articolo su rivista]
Ferrari, C.; Muscio, Alberto; Siligardi, Cristina; Manfredini, Tiziano
abstract
Solar reflective materials, so called cool roofs, can be identified as one of the most promising solutions to counteract urban heat island. Cool roof market is nowadays dominated by polymeric product, which can ensure good optical properties but poor durability against weathering and ageing. Ceramic-based products can be an excellent solution combining both good solar properties and higher durability against time, in particular if glazed. Embedded colored pigments, moreover, can help the introduction of these materials in Mediterranean building policies. These cool colored ceramic-based products, in fact, match naturally high thermal emissivity (ε=0.90) with higher mechanical, chemical and physical durability. A traditionally engobed porcelain stoneware tile was used as a substrate for a new generation of colored glazes characterized by different surfaces reaching promising values in solar reflectance.
2015
- Review on the Influence of Biological Deterioration on the Surface Properties of Building Materials: Organisms, Materials, and Methods
[Articolo su rivista]
Ferrari, Chiara; Santunione, Giulia; Libbra, Antonio; Muscio, Alberto; Sgarbi, Elisabetta; Siligardi, Cristina; Barozzi, Giovanni Sebastiano
abstract
A strong attention is recently paid to surface properties of building materials as these allows controlling solar gains of the building envelope and overheating of buildings and urban areas. In this regard, deterioration phenomena due to biological aggression can quickly damage solar-reflecting roof surfaces and thus increase sharply solar gains, discomfort, air-conditioning costs and waterproofing degradation. The same deterioration problem has deleterious effect on cultural heritage, ruining its huge historic and artistic value. This work is aimed at providing an overview on the different organisms that affect the surface of most used building materials, to support the design of new building materials with long-lasting surface properties and to find a way to preserve cultural heritage. Artificial ageing is the long-term aim of this investigation, in which what in nature happens after months or years is compressed in a very short time by forcing the growth of microorganisms through a strict control on the different conditioning factors. Both natural and artificial ageing are eventually outlined in the last part of this work to provide a comprehensive idea of what is necessary to study in a complete way biological ageing protocols on building materials. Several characterization techniques are also introduced to analyse the influence of microorganisms on the surface of different building materials.
2015
- Superfici "cool" ad alta riflettanza solare per il benessere animale nell'allevamento da latte
[Relazione in Atti di Convegno]
Santunione, Giulia; Libbra, Antonio; Muscio, Alberto
abstract
2014
- Creation of experimental urban indices in order to estimate the environmental performance of urban/building regenerations
[Articolo su rivista]
F., Bonazzi; M., Capucci; Muscio, Alberto; C., Rizzo
abstract
Identifying indices to measure the multiple environmental effects of urban transformations is the battle line for the urban planners. To tackle this need the Municipality of Modena (Italy) has defined a set of parameters focused on three main phenomena: the Urban Heat Island, energy requirements and hydraulic risk. The indicesare capable of measuring the effects, vouching for the achievement of the planning targets and estimating the benefit-cost ratio. The paper describes the pilot actions of the CE program’s project UHI realized in the framework of the Plan of Urban Redevelopment of the ‘Villaggio Artigiano’ (POC.MO.W, Modena).
2014
- Effect of aging processes on solar reflectivity of clay roof tiles
[Articolo su rivista]
Ferrari, Chiara; A., Gholizadeh Touchaei; M., Sleiman; Libbra, Antonio; Muscio, Alberto; Siligardi, Cristina; H., Akbari
abstract
Clay roof tiles are widely used as roofing materials because of their good mechanical and esthetical properties. The exposure to atmospheric agents and, most of all, to pollutants and smog affects negatively the solar reflectance of a tile surface. The aim of this study is to analyze the influence of aging on the solar reflectance of clay roof tiles. We studied samples provided by manufacturer in Greece and USA. Samples were coated with either organic or inorganic coatings. Natural aging processes were used for samples with inorganic coating, and artificial aging simulation was performed on all samples. Samples were naturally aged in a test farm in Arizona, with an exposure time of three years. In artificial aging processes, the surface of the tiles was subjected to the application of two different mixtures simulating exposure to (i) Arizona weathering agents such as clay, salts and soot and (ii) Arizona, Florida and Ohio weathering agents through an average mixture made by clay, salts, particulate organic matter and soot. The amount of soiling mixture deposited on the surface of the samples was aimed at reproducing a three-year exposure. Soiled samples were subjected to air blowing and rinsing under running water to simulate the wind and rain effects, respectively. The effects of both natural aging and artificial soiling on the surface reflectivity of the clay roof tiles were assessed in the ultraviolet–visible–near infrared range (range from 300 to 2500 nm). The two different soiling conditions were found to affect significantly the solar reflectance of the samples, in particular the samples soiled with the average mixture present a decrease up to 0.20, while Arizona weathering condition affects the solar reflectance up to 0.05, and neither air blowing nor rinsing seem to permit a significant recovery of the surface properties. All solar reflectance measurements were computed by averaging the spectral reflectivity weighted by the air-mass 1 global horizontal solar spectral irradiance.
2014
- Energy and economical comparison of possible cultures for a total-integrated on-field biodiesel production
[Relazione in Atti di Convegno]
Allesina, Giulio; Pedrazzi, Simone; S., Tebianian; Muscio, Alberto; Tartarini, Paolo
abstract
This work is aimed at investigating the energy conversion effectiveness and the economical advantages of a total integrated solution for on-field biodiesel and electrical energy production. The system proposed here is based on the synergy of four sub-systems: a seed press for oil production, a downdraft gasifier, a biodiesel conversion plant and a Solid Oxide Fuel Cell (SOFC). Two possible culture rotations, suggested by literature review, were analyzed here from economical and energy balance points of view. Both the rotations were composed of oleaginous crops only, therefore the seeds collected from the different cultures were pressed, then the protein cake produced in the process was gasified in the downdraft reactor. The gasification process was modeled here, and its output suggested that, for a precise number of hectares, the syngas obtained through the cake gasification was enough for producing methanol required for oil-biodiesel conversion and feeding a 10-kW SOFC. The purge line in the methanol reactor was used in the SOFC as well. The system was simulated using ASPEN PLUSTMand MATLABTMcodes. Results of the SOFC and gasifier models underlined the capability of the fuel cell to work with this particular system, furthermore the whole system analysis suggested that the surface required for sustainability of the processes is a function of the rotation choice. In both cases little surfaces ranging from 11 to 21 hectares were found to be enough for system self-sustainability with a ROI under 7 years in all the operating conditions analyzed.
2014
- Isola di calore e surriscaldamento estivo: cool colors in laterizio
[Articolo su rivista]
Ferrari, Chiara; A., Libbra; Muscio, Alberto; Siligardi, Cristina
abstract
La riflettanza solare delle coperture varia a seconda del tempo e del luogo di esposizione
ed è influenzata dai fenomeni naturali. I manti in laterizio si dimostrano un eccellente
candidato, in funzione dell’edilizia ad alta efficienza energetica, sia per il contrasto
dell’isola di calore urbana che per comfort indoor e la limitazione dei consumi estivi
2014
- Preliminary analysis of urban surfaces for the characterizaͳ tion and the mitigation of the heat island effect
[Relazione in Atti di Convegno]
Despini, Francesca; Teggi, Sergio; Muscio, Alberto; Ghermandi, Grazia
abstract
The urban heat island (UHI) phenomenon is an issue of growing interest and the subject of numerous studies. UHI is defined as the metropolitan area that is significantly warmer than its surrounding rural areas. UHI has significant impacts on the buildings energy consumption and outdoor air quality, therefore it is considered an important environmental topic. The most effective approaches to mitigate UHI include, among others, the albedo increase of materials used for manmade surfaces (e.g. pavements, roofs), the increment of vegetated areas (e.g. parks, flowerbed, gardens), the increment of water surfaces (e.g. ponds). The UHI mitigation results in a reduction of the energy consumption and in an improvement of outdoor air quality. A recent model study carried by Rossi et al. (CIRIAF, University of Perugia) correlated the increase of materials albedo with energy saving in terms of reduction of carbon dioxide emissions. Therefore surfaces characterization is an useful information for planning UHI mitigation actions. Albedo of different types of urban surfaces can be obtained from bibliographic data, from laboratory measurements or retrieved from spaceborne or airborne remote sensing data. This data reported surface reflectance for each band, from which albedo can be directly obtained. In this work, airborne remote sensing data have been used for UHI characterization and for the study of UHI mitigation. The area of interest is the city of Modena in the Emilia Romagna region (Italy). On this area four orthorectified images acquired in the electromagnetic regions of the visible and near-infrared by an airborne sensor with a spatial resolution of 2 meters are used. Using an object-oriented technique, the four images have been segmented and classified into categories representing different types of land cover significant for UHI: Cultivated Soils, Green Areas, Roads, Parking, Railways and Buildings. The "Buildings" class is further divided in pitched roofs made of tiles (typical buildings of the historical center of the city) and in flat roofs of industrial buildings with both bright and dark coverings. This information will be used in the model described above in order to study UHI mitigation. This study presents some preliminary results of the application of this methodology that will be developed in the upcoming years for the application to various sites of interest.
2014
- Thermal Stabilization of Digesters of Biogas Plants by Means of Optimization of the Surface Radiative Properties of the Gasometer Domes
[Relazione in Atti di Convegno]
Bavutti, M.; Guidetti, L.; Allesina, G.; Libbra, A.; Muscio, A.; Pedrazzi, S.
abstract
A new incentive scheme for power generation from biogas is favoring in Italy the construction of small plants. These ones, however, have poorer financial viability and biological stability than larger plants. In order to ensure adequate performance and a reasonable payback period it is therefore essential that every aspect of their operations is carefully designed. In this respect, summer overheating of anaerobic digesters due to solar gains must be prevented. A solution relies upon the implementation of a ‘cool’ gasometer dome with properly chosen solar reflectance, whose effectiveness was assessed through the use of a calculation code specifically built and validated by comparison with experimental data.
2013
- Biodiesel production through sinergy of on-field PVO extraction and protein cake gasification
[Relazione in Atti di Convegno]
Allesina, Giulio; Muscio, Alberto; S., Tebianian; Pedrazzi, Simone; Tartarini, Paolo
abstract
This work is aimed at demonstrating the advantages of on-field oil extraction and protein cake exploitation from biomasses produced by a three-years crop rotation. The rotation that has been taken into account is rapeseed-sunflowerflax, suitable for most Mediterranean climatic zones.
The process is divided in differents phases: extraction of pure vegetable oil (PVO) from seeds, gasification of the protein cake remaining from oil extraction and trans-esterification of the PVO using the methanol obtained by conversion of part of the syngas from gasification. In this way, instead of selling the seeds to the market, it is possible to sell the biodiesel and the electrical energy obtained from an IC engine operating with the excess of syngas. The effectiveness evaluation of this approach has been obtained through energetic and economical modeling of the whole system.
The system has been simulated using ASPEN PLUSTM and MATLABTM codes. The results show the advantages related to the installation of micro power plants of 10 kWel, involving little surfaces tilled. The minimum surface necessary for system self-sustainability has been estimated as a function of field productivity and fuels characteristics. Moreover, the outputs of the
economical analysis show the effectiveness of this innovative approach.
2013
- Design of ceramic tiles with highsolar reflectance through
the development of a functional engobe
[Articolo su rivista]
Ferrari, Chiara; Libbra, Antonio; Muscio, Alberto; Siligardi, Cristina
abstract
Roofing solutions with high capacity to reflect incident solar radiation, the so-called cool roofs, can provide an effective answer to summer overheating of either individual buildings or whole urban areas. Nowadays, commercial cool roofs products are mainly represented by organic membranes and coatings, but ceramic tiles can represent an interesting alternative or complement in view of their low maintenance cost. In this work, it is illustrated how a high reflectance engobe can affect in a positive way the solar reflectance of a glazed tile thanks to the introduction of suitable raw materials and pigments. The reflectance was in fact found to be affected by either the support, the mineralogical composition, the engobe thickness or the glaze. The procedure through which the glazed tile is developed and tested is discussed, in the perspective of production through commonly used industrial processes.
2013
- Effect of ageing processes on solar reflectivity of clay roof tiles
[Relazione in Atti di Convegno]
Ferrari, Chiara; A. G., Touchaei; M., Sleiman; Libbra, Antonio; Muscio, Alberto; Siligardi, Cristina; H., Akbari
abstract
Clay roof tiles are widely used as roofing materials because of their good mechanical and aesthetical properties. The exposure to atmospheric agents and, most of all, to pollutants and smog affects negatively the solar reflectance of atile surface. The aim of this study is toanalyzethe influence of ageing on the solar reflectance of clay roof tiles. We studied samples provided by manufacturer in Greece and USA. Samples were coated with either organic or inorganic based coating. Natural ageing processes were used for samples with inorganic coating, and artificial ageing simulation was performed on all samples. Samples were naturally aged in a test farm in Arizona, with an exposure time of 3 years. In artificial ageing processes, the surface of the tiles was subjected to the application of two different mixtures simulating exposure to i) Arizona weathering agents such as clay, salts and soot and ii) Arizona, Florida and Ohio weathering agents through an average mixture made by clay, salts, particulate organic matter and soot. The amount of soiling mixture deposited on the surface of the samples was aimed at reproducing a 3 years exposure. Soiled samples were subjected to air blowing and rinsing under running water to simulate the wind and rain effects, respectively. The effects of both natural ageing and artificial soiling on the surface reflectivity of the clay roof tiles were assessed in the UV-Vis-NIR range (range from 300 to 2500 nm). The two different soiling conditions were found to affect significantly the solar reflectance of the samples, in particularthe samples soiled with the average mixture present a decrease up to 0.20, while Arizona weathering condition affects the solar reflectance up to 0.05, and neither air blowing nor rinsing seem to permit a significant recovery of the surface properties. All solar reflectance measurements were computed by averaging the spectral reflectivity weighted by the AM1GH solar spectral irradiance.
2013
- Energy performance of opaque building elements in summer:Analysis of a simplified calculation method in force in Italy
[Articolo su rivista]
Libbra, Antonio; Muscio, Alberto; Siligardi, Cristina
abstract
The Italian technical standard for calculation of building energy needs in summer allows a monthlyaverage method, in which solar gains through opaque building elements are evaluated distinguishingbetween dark, intermediate or light-colored surfaces, and a fixed value of solar absorptance is assigned toeach surface category. The method is aimed at ease of operation, but its steady-state calculation approachmay not allow taking into proper account dynamic effects due to thermal inertia. Moreover, roofingsolutions typical of Italy such as roof tiles, sealing membranes or painted sheet metal panels can showsimilar colors, but significantly different values of the solar absorption coefficient. On the other hand, aneasy to apply calculation method may enable most designers of the building sector to take advantage ofsolutions for control of solar gains such as cool roofs and cool colors, thus favoring their dissemination.In this paper, the calculation method currently in use in Italy is briefly presented, with the focus onthe role of opaque building elements. Either the accuracy of steady-state calculation or the reliabilityof the color-based evaluation approach is then discussed, analyzing by numerical simulation the actualdynamic behavior of most common types of roof element.
2013
- In-field evaluation of the absorption coefficient of the external surface of the insulated box in a refrigerated vehicle.
[Relazione in Atti di Convegno]
S., Rossi; P., Bison; A., Bortolin; G., Cadelano; G., Ferrarini; Libbra, Antonio; Muscio, Alberto
abstract
The ATP (Agreement Transport Perishables) is mainly focused on the insulated boxes of the refrigerated vehicles. Until now, in the design of these boxes, the heat flux due to the sun radiation has been neglected despite its importance. The heat flux is driven by the solar absorption coefficient of the outer surfaces of the boxes; recently a thermal approach for the quick evaluation of this parameter has been proposed. A small region of the external surface is varnished with a paint of known absorption coefficient, then the whole surface is subjected to a variation of illumination that leads to a temperature increase. If the thermal parameters are the same all over the panel, the comparison between the two temperature profiles gives the absorption coefficient value. In this paper a varnish is characterized and the thermal technique is applied on specimens and vehicles using different data acquisition systems.
2013
- Influence of the irradiance spectrum on solar reflectance measurements
[Articolo su rivista]
Ferrari, Chiara; Libbra, Antonio; Muscio, Alberto; Siligardi, Cristina
abstract
Solar reflectance (SR) is the key performance parameter of cool roof and cool pavement materials. For its assessment, the measured spectral reflectivity of the sample is weighted by a reference spectrum of solar irradiance. Several standard and non-standard spectra are, however, available, taking into account different climate conditions, angle of incidence of the solar beam, and the contribution of the diffuse radiation content. This study is aimed at investigating the impact of using different solar irradiance spectra as specified by existing standards or suggested by qualified research institutions, and verifying if those spectra can yield equivalent SR values from the viewpoint of assessment of standard performance and comparison of commercial products. Several actual material are considered, either white or coloured ones and with assorted spectral behaviour.
2013
- Influence of the solar irradiance spectrum on solar reflectance measuremens
[Relazione in Atti di Convegno]
Ferrari, Chiara; Libbra, Antonio; Muscio, Alberto; Siligardi, Cristina
abstract
Solar reflectance is the key performance parameter of cool roof and cool pavement materials. For its assessment, the measured spectral reflectivity of the sample is weighted by a reference spectrum of solar irradiance. Several standard and non-standard spectra are however available, taking into account different climate conditions, angle of incidence of the solar beam, contribution of the diffuse radiation content.
This study is aimed at investigating the impact of using different solar irradiance spectra as specified by existing standards or suggested by qualified research institutions, and verifying if those spectra can yield equivalent solar reflectance values from the viewpoint of assessment of standard performance and comparison of commercial products. Several actual material are considered, either white or coloured ones and with assorted spectral behaviour.
2013
- Interlaboratory comparison of cool roofing material measurement methods
[Relazione in Atti di Convegno]
A., Synnefa; A., Pantazaras; M., Santamouris; E., Bozonnet2; M., Doya; M., Zinzi; Muscio, Alberto; Libbra, Antonio; Ferrari, Chiara; V., Coccia; F., Rossi; D., Kolokotsa
abstract
The present study aims at investigating different methodologies and standards for measuring and calculating solar reflectance and infrared emittance, the two main properties characterizing cool roofing materials. In order to achieve this goal, an interlaboratory comparison testing has been set up among several laboratories that are members of the European Cool Roofs Council. The measurement methods practiced by the labs include measurement of the reflectivity by using spectrophotometers equipped with integrating spheres and reflectometers and measurement of the emissivity using different emissometer devices and FTIR spectrometers equipped with integrating spheres. Seventeen different samples representing the range of commercially available roofing materials and covering the full range of reflectance and emittance values have been selected and tested. The results of this study provide information on the suitability of the various methods to be used for cool roof products assessment. This work could potentially lead to the adoption of a European Cool Roof Standard.
2013
- Modeling and simulation of a DG-SOFC-MGT hybrid system
[Relazione in Atti di Convegno]
Pedrazzi, Simone; Allesina, Giulio; Muscio, Alberto; Tartarini, Paolo
abstract
This paper describes the modeling and the simulation of an advanced gasification power plant composed of a Downdraft Gasifier (DG) and a Solid Oxide Fuel Cells - Micro Gas Turbine unit (SOFC-MGT). The gasifier converts the woodsy biomass into syngas that it is cooled and filtered before entering in a compressed storage tanks sub-system. A hybrid SOFC-MGT unit uses the stored syngas to produce electrical energy that it is sent to the electrical grid.
The system has been modeled starting from literature. The simulations were made for different types of woodsy biomass over a year long period. Poplar, peach tree and vineyards pruning have been adopted with a variable moisture content ranging
from 5% to 30%. The electrical energy produced and the overall electrical efficiency have been calculated setting the biomass consumption to 187 kg/hour for different biomasses and moistures scenarios. Maintenance of the gasifier has taken into account imposing a cycle of 120 hours of operating and 12 hours of maintenance. Starting from that, the storage sub-system has been design to assure the continuous operation of the SOFC-MGT unit all over the annual simulation.
Sensitive analysis of the performance of the system varying the biomass type and the biomass moisture have been developed in order to find the best working conditions. Moreover, the annual energy balance of the system has been evaluated with these conditions to point out where the most relevant energy losses take place.
Results show that the maximum overall electrical efficiency is around 33.5% for poplar biomass with 10% of moisture. In this scenario the average electrical power production is about 223 kW, the annual electrical energy amount sent to the grid is about 1956 MWh. In this conditions, the 42% of the chemical energy of the biomass is lost in the SOFC-MGT unit.
2013
- Reverse use of an infrared emissometer for measurement of thermal conductivity
[Abstract in Atti di Convegno]
Libbra, Antonio; Muscio, Alberto
abstract
A broadband emissometer based on the ASTM C1371 test method is exploited to measure the thermal conductivity of non-metallic solid materials when these are available in form of thin specimens. The instrument is designed to estimate the infrared emissivity by placing a hot probe with controlled temperature on the specimen surface and measuring the net radiative heat flow rate between probe and surface by means of a thermopile. Placing the probe on a specimen with low conductivity causes the specimen surface to overheat with respect to ambient, and the net radiative heat flow rate between probe and surface to decrease. From the signal measured by the thermopile after the probe-specimen system reaches steady state it is possible to retrieve an estimate of the thermal conductivity
2013
- Thermal stabilization of digesters biogas plants by means of optimization of the surface radiative properties of the gasometer domes
[Abstract in Atti di Convegno]
M., Bavutti; L., Guidetti; Libbra, Antonio; Muscio, Alberto
abstract
New incentivation schemes for power generation from biogas favor in Italy the construction of small plants. These ones, however, have poorer financial viability and biological stability than larger plants. For small plants it is therefore essential that every aspect of their operations is carefully designed to ensure maximum performance and a reasonable payback period. In this respect, summer overheating of anaerobic digesters due to solar gains through the gasometer domes must be prevented as it can undermine the profitability of biogas plants. A solution relies upon the implementation of a ‘cool’ gasometer, that is a gasometer dome with properly chosen radiative surface properties. The study presented here allowed assessing the effectiveness of the proposed approach with a standard biogas plant with 250 kWe power through the use of either commercial software or a calculation code specifically built and validated on the basis of experimental data. More specifically, it was found that the adoption of coatings with proper solar reflectance and thermal emittance for the membranes of the gasometer dome permits to significantly reduce summer overheating in the digesters, with appreciable economic benefits in the face of a modest investment
2012
- Analisi della conduttività termica di progetto dei materiali da costruzione
[Relazione in Atti di Convegno]
A., Lambruschi; Muscio, Alberto
abstract
In questo periodo caratterizzato da profondi cambiamenti climatici e da continui allarmi da parte degli studiosi sul riscaldamento globale, la Comunità Europea ha deliberato una serie di norme destinate al settore edilizio che mirano a contenere e ridurre in maniera drastica i fabbisogni di energia primaria degli edifici.
In particolare la direttiva 2010/31/UE [1] impone, per i privati, che le nuove costruzioni e le ristrutturazioni importanti siano ad energia quasi zero.
La riduzione del fabbisogno di energia primaria, dipende direttamente dal grado di isolamento termico dell’involucro e quindi dalla quantità di isolante impiegato e dalle caratteristiche dello stesso.
Il presente studio non mira a caratterizzare l’incidenza dei fabbisogni specifici, quanto l’incidenza che i coefficienti maggiorativi hanno sulla determinazione della trasmittanza dell’involucro opaco e quindi sul fabbisogno di energia termica di involucro.
2012
- Analisi tecnica, energetica ed economica degli impianti di ventilazione meccanica controllata installati in edifici esistenti
[Relazione in Atti di Convegno]
Alex, Lambruschi; Muscio, Alberto
abstract
La limitazione dei fabbisogni energetici degli edifici è un obiettivo prioritario per tutta l’Unione europea, in cui sono comprese aree territoriali fortemente antropizzate. Azioni incentivanti ed imposizioni normative sono perciò in continua evoluzione, in relazione sia agli edifici di nuova costruzione che al patrimonio edilizio esistente. Anche in Italia, gli interventi di risanamento energetico degli edifici esistenti, a livello di involucro e di impianti, sono attualmente supportati da specifici incentivi fiscali. Tra i vari tipi di intervento che si possono adottare passa spesso in secondo piano l’adozione di sistemi di ventilazione meccanica controllata, che pure offre interessantissime opportunità, tanto dal punto di vista della riduzione dei fabbisogni energetici quanto da quello del miglioramento del confort e della qualità dell’aria negli ambienti abitati. In questo lavoro si intende tracciare il quadro della normativa inerente la ventilazione degli ambienti e gli impianti di ventilazione meccanica controllata, con particolare riferimento alla riqualificazione degli edifici residenziali. Si svilupperà, quindi, un’analisi critica delle tecnologie utilizzabili, con l’intento di formulare proposte di intervento contraddistinte da semplicità di realizzazione e di calcolo.
2012
- Increase of Net Power Generation Of Biogas Plants By Reduction Of Heat Loss
[Relazione in Atti di Convegno]
G., Grinzi; L., Guidetti; Allesina, Giulio; Libbra, Antonio; P., Martini; Muscio, Alberto
abstract
in this work, a comprehensive mathematical model of a biogas power generation plant is exploited to investigate the advantages of heat loss reduction. The model allows simulating the whole generation process, from biological breakdown of the biomass mixture to final generation of electricity and heat by combustion of the biogas. Either a thermal sub-model of the digestors or a fluid-dynamic sub-model of ducts and heat exchangers of the auxiliary heating system have been implemented, in order to evaluate heat loss, head loss in the ducts and power absorption of the pumps. An innovative approach to the exploitation of solar gains through the gasometer domes is also evaluated, based on the use of surface coatings with high solar absorptance and low thermal emittance. The theoretical reduction of auxiliary energy need is thus predicted as a function of local meteorological data on a monthly average. The results of the analysis show that proper insulation of the digestors and coating of the gasometer domes can increase the net production of electric energy up to a few percentage points. If waste heat is also exploited externally, the net increase of heat production is much greater, especially in cold climates.
2012
- Insulating behavior of metakaolin-based geopolymer materials assess with heat flux meter and laser flash techniques
[Articolo su rivista]
Kamseu, Elie; B., Ceron; H., Tobias; Leonelli, Cristina; M. C., Bignozzi; Muscio, Alberto; Libbra, Antonio
abstract
Thermo physical behavior of metakaolin-based geopolymer materials was investigated. Five compositions of geopolymers were prepared with Si/Al from 1.23 to 2.42 using mix of sodium and potassium hydroxide (~7.5 M) as well as sodium silicate as activator. The products obtained were characterized after complete curing to constant weight at room temperature. The thermal diffusivity (2.5-4.5 × 10-7m2/s) and thermal conductivity (0.30-0.59 W/m K) were compared to that of existing insulating structural materials. The correlation between the thermal conductivity and parameters as porosity, pore size distribution, matrix strengthening, and microstructure was complex to define. However, the structure of the geopolymer matrix, typical porous amorphous network force conduction heat flux to travel through very tortuous routes consisting of a multiple of neighboring polysialate particles.
2012
- Investigation of an equivalence criterion between periodic thermal transmittance of opaque building elements and cool roof or cool color coatings
[Relazione in Atti di Convegno]
Lodi, Chiara; Ferrari, Fabio; Muscio, Alberto; Tartarini, Paolo
abstract
At this time, just a few requirements have been introduced in Italy about the summer performance of buildings, one among them concerning the maximum allowed value for the periodical thermal transmittance of opaque building elements. In fact, it is generally assumed that thermal cycles induced by solar radiation at the external surfaces can be substantially damped through the thickness of roofs and walls thanks to properly low values of their periodic thermal transmittance. The result is generally achieved by giving roofs and walls an adequate levels of either thermal insulation or thermal inertia, but this is generally reflected in the adoption of a high surface mass and makes it difficult to use wooden roofs, plasterboard structures or sandwich panels with foam insulation. However, using an outer coating with high solar reflectance, identified with the terms of cool roof or cool color in the technical nomenclature used in the U.S.A., permits to dampen the thermal cycles induced by solar radiation directly at the outer surface rather than through the thickness. In the present paper, we investigate an equivalence criterion between periodic thermal transmittance and solar reflectance by means of dynamic calculation approaches. The criterion is studied in terms of containment of either thermal energy needs for air conditioning or discomfort of the built environment.
2012
- Sportswear textiles emissivity measurement: comparison of IR thermography and emissometry techniquBison, P.a, Grinzato, E.a, Libbra, A.b, Muscio, A.
[Relazione in Atti di Convegno]
P., Bison; E., Grinzato; Libbra, Antonio; Muscio, Alberto
abstract
Three sportswear textiles are compared, one normal and two 'special' with Ag+ ions and Carbon powder added, with different colors. The emissivity of the textiles has been measured to determine if it is increased in the 'special' textiles with respect to the normal one. The test implied some non-standard procedure due to the semitransparent nature of the textiles, in comparison with the normal procedure that is commonly used on opaque surfaces. The test is also carried out by a standard emissometry technique, based on a comparative approach with reference samples having known thermal emissivity. The results are compared and discussed.
2012
- Sportswear textiles emissivity measurement: comparison of IR thermography and emissometry techniques
[Relazione in Atti di Convegno]
P., Bison; E., Grinzato; Libbra, Antonio; Muscio, Alberto
abstract
Three sportswear textiles are compared, one normal and two 'special' with Ag+ ions and Carbon powder added, with different colors. The emissivity of the textiles has been measured to determine if it is increased in the 'special' textiles with respect to the normal one. No substantial increase has been noticed. Nonetheless, the test implied some non-standard procedure due to the semitransparent nature of the textiles, in comparison with the normal procedure that is commonly used on opaque surfaces. The test is also carried out by IR emissometry technique. The results are compared and discussed.
2012
- Stabilizzazione termica di digestori di impianti biogas mediante ottimizzazione delle proprietà radiative delle cupole gasometriche
[Relazione in Atti di Convegno]
G., Grinzi; L., Guidetti; Libbra, Antonio; Muscio, Alberto
abstract
Questo lavoro si propone di indagare mediante modellazione matematica una strategia di contenimento delle oscillazioni di temperatura all’interno dei digestori di impianti per la produzione di biogas da fermentazione anaerobica di biomasse. Tale strategia, basata sull’ottimizzazione delle proprietà radiative delle cupole gasometriche che chiudono superiormente i digestori, è finalizzata a stabilizzare la produzione del biogas e, quindi, dell’energia elettrica da questo ottenibile.
Attraverso l’analisi dei fenomeni fisici che possono condizionare gli scambi termici tra biogas nel digestore, cupola gasometrica ed ambiente esterno, si indaga l’impatto degli apporti solari e delle dispersioni termiche sul comportamento termico e biologico dei digestori, verificando in particolare le potenzialità, in termini di regolarizzazione degli scambi termici suddetti, di soluzioni di trattamento superficiale delle membrane della cupola gasometrica contraddistinte da elevata riflettanza solare e/o bassa emissività termica.
2012
- Valutazione sperimentale del coefficiente di assorbimento ottico di un pannello sandwich utilizzato nell'allestimento di veicoli refrigerati
[Relazione in Atti di Convegno]
P., Bison; A., Bortolin; G., Cadelano; G., Ferrarini; Libbra, Antonio; Muscio, Alberto; S., Rossi
abstract
L’influenza della radiazione solare nel computo energetico globale dei veicoli refrigerati non può essere trascurata, in particolar modo nei Paesi dove le temperature esterne raggiungono e superano i 30°C per molte settimane all’anno (come avviene in generale nel Sud dell’Europa). L’apporto energetico dovuto al flusso solare diventa preponderante nel caso in cui un veicolo si trovi fermo nelle ore più calde della giornata, come si può facilmente verificare con semplici modelli di simulazione [1]. Discende dalle considerazioni sopra esposte che lo studio delle proprietà ottiche delle superfici esterne delle casse isolate riveste una particolare importanza, sia per quanto riguarda la tematica di inquinamento ambientale (la maggior parte dei veicoli frigoriferi attualmente sulla strada utilizzano motori Diesel), sia per quanto riguarda il problema della riduzione dei costi nel trasporto e da ultimo per la necessità di ridurre i consumi energetici specialmente in settori come la refrigerazione e la catena del freddo [2-5]. La sicurezza alimentare implica inoltre la necessità di utilizzare contenitori con un elevato coefficiente globale di isolamento, in grado quindi di assorbire la minor quantità di radiazione solare possibile. L’obbiettivo di questo lavoro è, in conclusione, quello di dimostrare la fattibilità di una metodologia di prova a basso costo per la misura “sul campo” del coefficiente di assorbimento dei pannelli isolati costituenti la superficie esterna dei veicoli.
2011
- Assessment and improvement of the performance of antisolar surfaces and coatings
[Articolo su rivista]
Libbra, Antonio; Muscio, Alberto; Siligardi, Cristina; Tartarini, Paolo
abstract
Solar reflectance and thermal emittance are key parameters to evaluate solar heat gains through opaquebuilding elements. A high solar reflectance allows building surfaces to minimize absorption of solarenergy, whereas a high thermal emittance allows returning to the environment most of the solar energythat is however absorbed by any actual surface. Therefore, summer overheating of buildings can beprevented by selecting external coatings with proper values of both properties.In this work, the role of radiative properties is explained in quantitative terms. Standard test methodsfor their measurement are also presented. The behavior of some typical cool roof surfaces is then analyzed,in order to point out the limits of qualitative selection criteria and demonstrate the need of quantitativeapproaches to enable product comparison and development. Eventually, the perspectives offered by theuse of advanced materials and coatings are also highlighted.
2011
- Atti XVII Convegno A.I.P.T.
[Curatela]
E., Campagnoli; Muscio, Alberto
abstract
Atti del XVII Convegno dell'A:I.P.T. - Associazione Italiana Proprietà Termofisiche, tenutosi a Padova il 30 Settembre 2011. Raccolta delle memorie relative ai diversi lavori presentati al convegno
2011
- Atti del Quinto Congresso Nazionale dell'AIGE -Associazione Italiana Gestione EnergiaUniversità diModena e Reggio Emilia, Facoltà di Ingegneria diModena8-9 giugno 2011
[Curatela]
Muscio, Alberto
abstract
Atti del Quinto Congresso Nazionale dell'AIGE -Associazione Italiana Gestione EnergiaUniversità diModena e Reggio Emilia, Facoltà di Ingegneria diModena8-9 giugno 2011
2011
- Elementi di fisica tecnica per l'ingegneria
[Traduzione di Libro]
Corticelli, Mauro Alessandro; Barozzi, Giovanni Sebastiano; Muscio, Alberto; Stalio, Enrico; Tartarini, Paolo
abstract
Scopo del testo è introdurre ai principi della termodinamica, della meccanica dei fluidi e della trasmissione del calore attraverso un approccio integrato, assai importante per lo studente ingegnere
2011
- La questione delle maggiorazioni ex UNI 10351 sulla conducibilità termica dei materiali per l’edilizia: risultati di una campagna di verifica mediante apparato hot-box
[Relazione in Atti di Convegno]
Francesco, Tardini; Massimiliano, Magagnoli; Giancarlo, Ferrero; Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
La limitazione dei fabbisogni energetici degli edifici è un obiettivo prioritario per tutta l’Unione europea, in cui sono comprese aree territoriali fortemente antropizzate. Azioni incentivanti ed imposizioni normative sono perciò in continua evoluzione, in relazione sia agli edifici di nuova costruzione che al patrimonio edilizio esistente. Anche in Italia, gli interventi di risanamento energetico degli edifici esistenti, a livello di involucro e di impianti, sono attualmente supportati da specifici incentivi fiscali. Tra i vari tipi di intervento che si possono adottare passa spesso in secondo piano l’adozione di sistemi di ventilazione meccanica controllata, che pure offre interessantissime opportunità, tanto dal punto di vista della riduzione dei fabbisogni energetici quanto da quello del miglioramento del confort e della qualità dell’aria negli ambienti abitati. In questo lavoro si intende tracciare il quadro della normativa inerente la ventilazione degli ambienti e gli impianti di ventilazione meccanica controllata, con particolare riferimento alla riqualificazione degli edifici residenziali. Si svilupperà, quindi, un’analisi critica delle tecnologie utilizzabili, con l’intento di formulare proposte di intervento contraddistinte da semplicità di realizzazione e di calcolo.
2011
- Problematiche energetico-ambientali e misure di compensazione per gli impianti a biomasse legnose
[Relazione in Atti di Convegno]
Alex, Lambruschi; Giacomo, Bizzarri; Muscio, Alberto
abstract
SOMMARIOLa determinazione dei fabbisogni energetici convenzionali degli edifici e l’attribuzione agli stessi di una classe diprestazione energetica discendono dal calcolo del fabbisogno di energia soddisfatto dalle diverse fonti energetiche utilizzate,attualmente da valutare in termini di energia primaria attraverso coefficienti di conversione specifici per ogni fonte.A livello nazionale sono già stati prescritti specifici fattori di conversione per i combustibili fossili e per l’energia elettrica,ma non per fonti rinnovabili o assimilate quali le biomasse combustibili o per il calore ottenuto da processi cogenerativi oreflui termici.In questo lavoro si tenta di tracciare il quadro della normativa nazionale inerente la valutazione dell’energia primariaottenuta da fonti rinnovabili, nonché di quella consumata dai sistemi cogenerativi, considerando anche alcuni orientamenti alivello internazionale e regionale e sviluppando una analisi critica ispirata dai dettati fondamentali della Direttiva 2002/91/CE,con l’intento di formulare alcune semplici proposte di valutazione convenzionale, supportate da specifiche argomentazioni dinatura tecnico-scientifica e normativa.
2011
- Spectral response data for development of cool coloured tile coverings
[Articolo su rivista]
Libbra, Antonio; L., Tarozzi; Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
Most ancient or traditional buildings in Italy show steep-slope roofs covered by red clay tiles. As the rooms immediately below the roof are often inhabited in historical or densely urbanized centres, the combination of low solar reflectance of tile coverings and low thermal inertia of either wooden roof structures or sub-tile insulation panels makes summer overheating a major problem. The problem can be mitigated by using tiles coated with cool colours, that is colours with the same spectral response of clay tiles in the visible, but highly reflecting in the near infrared range, which includes more than half of solar radiation. Cool colours can yield the same visible aspect of common building surfaces, but higher solar reflectance.Studies aimed at developing cool colour tile coverings for traditional Italian buildings have been started. A few coating solutions with the typical red terracotta colour have been produced and tested inthe laboratory,using easily available materials. The spectral response and the solar reflectance havebeen measured and compared with that of standard tiles.
2011
- Thermal behavior of sunspaces obtained by conversion of existing balconies
[Relazione in Atti di Convegno]
A., Lambruschi; Muscio, Alberto
abstract
ABSTRACTThe evolution of technology, global warming induced by greenhouse gases and the economic crisis have prompted public administrators, professionals in the construction industry and even individuals to implement actions aimed at saving energy, in terms of either reducing the energy demand of buildings or increasing the use of renewable sources.In order to limit the energy needs for winter heating, attention at the legislative level has recently focused on the reduction of heat loss and a more efficient use of solar gains. The latter approach can be pursued not only by means of active solar systems, but also through passive systems such as attached solar sunspaces, which essentially reduce the temperature gradient and the heat loss through the outer walls.In this work, the performance of sunspaces applied to common architectural elements of Italian buildings such as small balconies is theoretically investigated on the basis of standard procedures for assessment of energy performance, in order to highlight their potential when applied to the energy refurbishment of existing buildings.
2010
- Actual solar reflectance of roof surfaces andstandard energy performance of Italian buildings in summer
[Relazione in Atti di Convegno]
Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
Solar reflectance or its complement to unity, solar absorptance, are key parameters to evaluate solar gains through opaque elements and predict summer performance of buildings. For their evaluation, Italian technical rule UNI/TS 11300-1 prescribes a standard approach based on colors, distinguishing between dark-, intermediate- and light-colored surfaces and assigning to each category a fixed value of solar absorptance or reflectance. This approach, however, may be simplistic. In fact, an experimental campaign performed at the Energy Efficiency Laboratory of the University of Modena and Reggio Emilia showed that typical materials for Italian building such as roof tiles, coated tiles, paints or sealing membranes can show similar colors, but very different values of solar properties.In this paper, the calculation method currently in force in Italy for solar gains is briefly presented and then applied to a general analysis. In particular, the range of variability for summer performance of buildings is discussed in relation to the color-based evaluation approach, also taking into account measurement results obtained for some roofing solutions typical of Italy.
2010
- Alcune considerazioni sulla conversione in energia primaria dei fabbisogni da fonti rinnovabili ed assimilate
[Relazione in Atti di Convegno]
A., Lambruschi; G., Bizzarri; Muscio, Alberto; Tartarini, Paolo
abstract
La determinazione dei fabbisogni energetici convenzionali degli edifici e l’attribuzione agli stessi di una classe di prestazione energetica discendono dal calcolo del fabbisogno di energia soddisfatto dalle diverse fonti energetiche utilizzate, attualmente da valutare in termini di energia primaria attraverso coefficienti di conversione specifici per ogni fonte.A livello nazionale sono già stati prescritti specifici fattori di conversione per i combustibili fossili e per l’energia elettrica, ma non per fonti rinnovabili o assimilate quali le biomasse combustibili o per il calore ottenuto da processi cogenerativi o reflui termici.In questo lavoro si tenta di tracciare il quadro della normativa nazionale inerente la valutazione dell’energia primaria ottenuta da fonti rinnovabili, nonché di quella consumata dai sistemi cogenerativi, considerando anche alcuni orientamenti a livello internazionale e regionale e sviluppando una analisi critica ispirata dai dettati fondamentali della Direttiva 2002/91/CE, con l’intento di formulare alcune semplici proposte di valutazione convenzionale, supportate da specifiche argomentazioni di natura tecnico-scientifica e normativa.
2010
- Analisi delle dinamiche di transizione di fase in materiali per accumulo termico incapsulati
[Relazione in Atti di Convegno]
Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
I materiali a transizione di fase per accumulo termico consentono di realizzare accumulatori con volumi, masse e superfici disperdenti molto contenuti, ma vanno opportunamente incapsulati per potersi interfacciare con il fluido termovettore degli impianti termoidraulici. Si pone perciò il problema dell'ottimizzazione delle geometrie e dei materiali delle capsule di contenimento, onde assicurare un efficiente scambio termico e, quindi, adeguate velocità di accumulo e rilascio del calore.In questo lavoro vengono esaminate e perfezionate alcune soluzioni analitiche utili a prevedere le dinamiche di avanzamento del fronte di transizione di fase in un PCM. Inoltre, viene presentato un modello numerico originale, atto a simulare con elevato livello di realismo i transitori termici dei PCM incapsulati. Il modello è stato validato tramite le soluzioni analitiche ed è stato infine sperimentato per indagare alcune problematiche fondamentali circa l’utilizzo dei PCM incapsulati.
2010
- Analisi di involucri edilizi con elevata inerzia termica integranti materiali a transizione di fase (PCM)
[Articolo su rivista]
Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
Un adeguato confort termoigrometrico estivo e la limitazione dei fabbisogni energetici per condizionamento possono essere conseguiti conferendo agli elementi dell’involucro edilizio un’inerzia termica sufficiente a smorzare le fluttuazioni di temperatura dovute al ciclo solare. Al tal fine, destano particolare interesse i materiali in grado di accumulare elevate quantità di energia termica sotto forma di calore latente di transizione di fase, i cosiddetti PCM (phase change material), la cui integrazione nell’involucro edilizio può consentire significativi benefici a parità di masse e spessori di parete, oppure considerevoli riduzioni delle masse e degli spessori stessi. In questo lavoro si riportano i risultati di alcune analisi sulla realizzazione e sulle problematiche di progettazione di elementi dell’involucro edilizio con massa superficiale contenuta ma elevata inerzia termica in virtù dell’integrazione di PCM.
2010
- Approaches for the assessment and improvement of performance of antisolar surfaces
[Relazione in Atti di Convegno]
Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
Solar reflectance and thermal emittance are key parameters to evaluate the solar heat gains through opaque building elements. A high solar reflectance allows building surfaces to minimize absorption of solar energy, whereas a high thermal emittance allows returning to the environment most of the solar energy that is however absorbed by any actual surface. Therefore, summer overheating of buildings can be prevented by selecting external coatings with proper values of both properties. In this work, the role of radiative properties is explained in quantitative terms and standard test methods for their measurement are briefly presented. The behavior of some typical cool roof surfaces is then analyzed, in order to point out the limits of qualitative selection criteria and demonstrate the need of quantitative approaches to enable product comparison and development. Eventually, the perspectives offered by the use of advanced materials and coatings are also highlighted.
2010
- Atti XVI Convegno A.I.P.T.
[Curatela]
E., Campagnoli; Muscio, Alberto
abstract
Atti del XVI Convegno dell'Associazione Italiana Proprietà Termofisiche, tenutosi a Modena il 24 Settembre 2010. Raccolta delle memorie relative ai diversi lavori presentati al convegno
2010
- Comparative Analysis of Different Methods to Evaluate the Thermal Conductivity of Homogeneous Materials
[Relazione in Atti di Convegno]
F., Asdrubali; G., Baldinelli; F., Bianchi; Libbra, Antonio; Muscio, Alberto
abstract
Thermal conductivity of materials for structural elements and thermal insulation represents a fundamental parameter in the assessment of the energy need of buildings. In this paper, two different systems for thermal conductivity measurement are compared, based respectively on the calibrated hot box and on the guarded hot plate methods. The study is specifically aimed at assessing the range of thermal transmittance where the hot box system is suitable and verifying the strengths and the weaknesses of the system.The comparison between measurements on specimens with different thermal conductivity and thickness showed that the two methods are substantially equivalent in the considered range of thermal conductivity, but are not completely interchangeable. In particular, the measurement campaign confirmed the expectation that the hot box system gives more accurate results with low thermal resistance samples.
2010
- Realizzazione e validazione preliminare di un apparato hot-box per la misura delle proprietà di trasmissione termica di elementi di parete in opera
[Relazione in Atti di Convegno]
F., Tardini; M., Magagnoli; G., Ferrero; Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
La normativa nazionale vigente nell’ambito della progettazione e della certificazione energetica degli edifici prevede la valutazione accurata della trasmittanza termica delle pareti opache e, in determinate condizioni, il rispetto di valori limite prestabiliti. Una corretta valutazione della trasmittanza termica risulta altresì fondamentale, a prescindere dalle prescrizioni normative, per prevedere l’effettivo comportamento termico delle singole pareti e dell’involucro edilizio nel suo complesso. Questo lavoro verte sullo sviluppo di un nuovo apparato di misura di tipo hot-box per la determinazione sperimentale della trasmittanza termica di pareti verticali in scala reale. L’apparato, realizzato da Kerakoll SpA in collaborazione con il Laboratorio per l’Efficienza Energetica (EELab) del Dipartimento di Ingegneria Meccanica e Civile di Modena, è basato su sensori di tipo termoflussimetrico ed è conforme alla norma tecnica UNI EN 1934:2000 [1]. In questa sede se ne fornisce un’ampia presentazione e si riportano alcuni risultati preliminari relativi al suo utilizzo.
2009
- Building structures with high thermal inertia based on phase change materials
[Articolo su rivista]
Barozzi, Giovanni Sebastiano; Corticelli, Mauro Alessandro; Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
In order to ensure the comfort of people who inhabit a building, the building envelope must have thermal inertia great enough to dampen its temperature fluctuations, in particular those due to the solar cycle. The use of materials that can accumulate large amounts of heat in the form of phase change latent heat, the so-called PCM, represents a very interesting approach to make buildings reactive to cyclical thermal loads and achieve better thermal performance with the same wall thickness, or the same thermal performance with reduced wall thickness.The present work is focused onto the development of roofs with small surface mass and high thermal inertia thanks to the integration of PCM. In particular, the relationship between properties of the PCM and thermal behaviour of the roof structure is investigated by numerical simulation. Moreover, the more convenient position of the PCM layer with respect to the thermal insulation layer is investigated for some typical structures to be protected against summer overheating.
2009
- Caratterizzazione analitica della pittura murale "Madonna con bambino, San Martino ed offerente" ritrovata nel chiostro della Chiesa di San Biagio al Carmine in Modena
[Articolo su rivista]
Baraldi, Pietro; Muscio, Alberto; Zannini, Paolo
abstract
Indagini analitico-strumentali sono state effettuate su di un dipinto murale del XIV secolo ritrovato fortuitamente nel 2005 durante i lavori di restauro del chiostro della Chiesa di San Biagio in Modena. Indagini in diffrattometria di raggi X, microscopia elettronica SEM-EDS, spettroscopia Raman, riflettografia UV e termografia IR sono state effettuate per stabilire la tecnica di realizzazione, la natura dei pigmenti e dei leganti, le problematiche di risalita capillare di umidità e per guidare i lavori di consolidamento e restauro.
2009
- Misure di conducibilità termica di materiali refrattari mediante un apparato a piastra calda con anello di guardia
[Articolo su rivista]
Boccaccini, Dino Norberto; Cannio, Maria; Veronesi, Paolo; Leonelli, Cristina; Muscio, Alberto
abstract
La conoscenza della conducibilità termica di prodotti ceramici sta assumendo importanza fondamentale per l’ottimizzazione dell’isolamento termico degli edifici in relazione alle problematiche connesse al risparmio energetico. Oggi esistono tecniche veloci, precise ed efficaci per la stima della conducibilità di materiali edilizi. Tuttavia per ottenere misure accurate di tale proprietà è opportuno scegliere il metodo di misura corretto in funzione dell’intervallo di conducibilità termica del materiale e della sua geometria. Nella realizzazione di un apparato a piastra calda con anello di guardia, nato dalla collaborazione tra DIMeC e DIMA, è stata seguita la norma ASTM C177-97. In particolare in questo lavoro viene mostrata la relazione tra conducibilità termica, densità e temperature di utilizzo di materiali refrattari
cordierite-mullite.
2009
- Misure di emissività termica su campioni a supporto non conduttivo
[Relazione in Atti di Convegno]
Libbra, Antonio; Muscio, Alberto
abstract
Il surriscaldamento estivo degli edifici sottoposti ad irradiazione solare può essere mitigato rivestendo o trattando le superfici irradiate in modo da conferire loro valori elevati sia della riflettanza solare, sia dell’emissività termica. Studi in tal senso sono stati avviati da alcuni anni presso il Dipartimento di Ingegneria Meccanica e Civile dell’Università di Modena e Reggio Emilia, il cui Laboratorio di Efficienza Energetica (EELab) è oggi dotato di strumenti per la misura delle proprietà radiative conformi ai più rigorosi e accettati standard internazionali.In questo lavoro si esamina il comportamento di uno di questi strumenti, un emissometro conforme allo standard ASTM C1371. Tale strumento è concepito per l’esecuzione di misure su superfici metalliche e su rivestimenti applicati a supporti metallici o comunque con elevata con conduttività termica. Nel caso si analizzino campioni con supporto poco conduttivo, sono proposte dal produttore dell’emissometro alcune specifiche procedure di misura, che vengono qui approfonditamente analizzate e messe alla prova.
2009
- Proprietà radiative superficiale esterne e fabbisogno energetico estivo dell’involucro edilizio
[Relazione in Atti di Convegno]
Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
La recente norma tecnica UNI/TS 11300 ha introdotto una metodologia di calcolo del fabbisogno energetico degli edifici armonizzata con gli standard di calcolo internazionali, ma incentrata sulle specificità del parco edilizio e delle tecniche edificatorie italiane. La norma fornisce una procedura adeguatamente articolata e completa per valutare sia il fabbisogno energetico invernale, sia quello estivo, su cui si focalizza il presente studio, tenendo in considerazione i principali processi di scambio termico che hanno luogo al contorno o entro gli elementi dell'involucro edilizio.In questo lavoro le procedure di calcolo degli apporti solari previste dalla norma UNI/TS 11300 vengono presentate sinteticamente e quindi applicate ad un caso di studio, analizzando in particolare l’impatto che le due principali proprietà radiative delle superfici irradiate, la riflettanza solare e l’emissività termica, possono avere sui guadagni solari attraverso gli elementi opachi dell’involucro edilizio e, quindi, sul fabbisogno termico estivo di un edificio.
2009
- Riflettanza solare ed emissività termica per l'efficienza energetica estiva degli edifici
[Articolo su rivista]
Libbra, Antonio; Muscio, Alberto; Tartarini, Paolo
abstract
Il raffrescamento estivo degli ambienti abitati comporta un fabbisogno energetico significativo, in molti casi superiore a quelle per riscaldamento invernale. Il legislatore nazionale si sta perciò accingendo ad introdurre limiti stringenti al consumo di energia anche in relazione alla climatizzazione estiva, focalizzandosi nella fase iniziale sull'involucro edilizio.Il principale carico termico da compensare ai fini del condizionamento estivo è generalmente quello conseguente agli apporti solari, che possono aver luogo sia attraverso gli elementi vetrati dell'involucro, sia attraverso quelli opachi. Nel secondo caso, la limitazione degli apporti può essere ottenuta intervenendo su proprietà delle superfici irradiate quali la riflettanza solare e l'emissività termica.In considerazione della necessità di conoscere e misurare la riflettanza solare e l'emissività termica ai fini dell'ottenimento di involucri edilizi efficienti, il Dipartimento di Ingegneria Meccanica e Civile di Modena ha recentemente strutturato uno specifico laboratorio, dotato di strumentazione rispondente ai migliori standard del settore. Il laboratorio ha già avviato studi scientifici ad ampio spettro sul controllo degli apporti solari ed ha allacciato con numerose aziende, rapporti di collaborazione tecnica finalizzati allo sviluppo di materiali e componenti innovativi per l'edilizia.
2009
- XXVII Congresso Nazionale UIT sulla Trasmissione del Calore
[Esposizione]
Dumas, Antonio; Sandrolini, Sandro; Muscio, Alberto; Trancossi, Michele; Anzillotti, Stefano; Bonnici, Maurizio; Zumbo, Francesco
abstract
An annual Congress organized by Unione Italiana di Termofluidodinamica, with the relevant international partecipation in the Scientific Committee and among the authors. Almost 60 papers are presented in the Congress regardingthe following themes: Monophase Thermofluiddynamics, Bi-phase thermofluidynamics, Heat Transfer,Thermo and fluiddynamics computational, Energetics annucleat energetic systems, Energetics and energetic system
2008
- Analisi della riflettanza spettrale di coating polimerici per cool colors
[Relazione in Atti di Convegno]
Libbra, Antonio; Muscio, Alberto
abstract
La maggior parte degli edifici dei centri storici italiani presentano tetti a falde inclinate. Poiché i locali posti immediatamente sotto i tetti sono spesso abitati, la combinazione dei tipici rivestimenti in tegole o coppi di terracotta, caratterizzati da limitata capacità di riflettere l'irradiazione solare, e delle strutture lignee dei tetti, contraddistinte da ridotta inerzia termica, fa del surriscaldamento estivo di attici e ambienti mansardati un problema di non poco conto. Tale problema può essere affrontato adottando tegole trattate superficialmente con "cool colors", cioè con rivestimenti aventi la stessa risposta spettrale nel visibile delle tegole di terracotta, e quindi lo stesso colore, ma in grado di riflettere molta più energia nella banda spettrale dell’infrarosso vicino, in cui è compresa oltre la metà dell’energia apportata dall'irradiazione solare.Studi volti a sviluppare cool colors per rivestimenti delle coperture di edifici tradizionali italiani sono stati avviati presso il Dipartimento di Ingegneria Meccanica e Civile dell’Università di Modena e Reggio Emilia. Alcuni rivestimenti con il tipico colore rosso terracotta sono stati prodotti e testati in laboratorio, privilegiando l’utilizzo di materiali di base di facile reperibilità. La riflettività spettrale e la riflettanza complessiva alla radiazione solare sono state misurate e confrontate con quelle caratteristiche della superficie di normali tegole in terracotta.
2008
- Analisi termografica all’infrarosso della distribuzione dei flussi d’aria in un tetto a ventilazione forzata
[Relazione in Atti di Convegno]
E., Caffagni; Libbra, Antonio; Muscio, Alberto; L., Tarozzi
abstract
Il surriscaldamento estivo di un tetto a falde inclinate sottoposto ad irradiazione solare può essere efficacemente mitigato attraverso la ventilazione forzata delle falde. L'approccio che qui si presenta prevede la ventilazione di un'intercapedine posta tra isolamento termico e manto in coppi e tegole, ottenuta aspirando l'aria alla gronda e raccogliendola in un collettore parallelo alla linea di colmo, da cui viene poi estratta tramite un ventilatore. Si rende in generale necessaria l'adozione di provvedimenti per uniformare la distribuzione dei flussi nell'intercapedine, la cui funzionalità viene qui verificata e migliorata mediante analisi termografia all'infrarosso.
2008
- Measurement of thermal diffusivity by a modification of the Angstroem's method using thermally short specimens
[Relazione in Atti di Convegno]
Muscio, Alberto
abstract
A modification of the Angstroem's method for measurement of thermal diffusivity is presented. The Angstroem's method relies upon the steady-periodic propagation of temperature waves along the specimen. The diffusivity is recovered from combination of phase shift and amplitude decay of the waves, measured by infrared thermography, under the hypothesis of virtually semi-infinite specimen, that is neglecting the reflection of temperature waves at the end of the specimen.In this work, a condition is exploited in which the specimen is not considered semi-infinite. Testing of a large set of materials is made possible, as well as recovering the diffusivity value from either amplitude decay or phase shift, independently. A procedure to estimate the diffusivity is developed from the mathematical model of the 'thermally short' specimen and it is subsequently validated by numerical simulation.
2008
- Microgeneratori ad effetto Peltier per dispositivi di contabilizzazione termica
[Relazione in Atti di Convegno]
Bertocchi, Luca; Libbra, Antonio; Muscio, Alberto
abstract
La generazione elettrica mediante dispositivi ad effetto Peltier è efficace e competitiva in situazioni di alimentazione di apparecchi delocalizzati a basso assorbimento di potenza.Lo studio svolto riguarda l'accoppiamento di microgeneratori ad effetto Peltier e contatori di consumo termico applicabili alle terminazioni radianti di un impianto di riscaldamento centralizzato con distribuzione a colonne montanti. Misurare il calore fornito alle varie unità abitative di un condominio può infatti richiedere l'installazione di un gran numero di contatori, fino ad uno per ogni corpo radiante, rendendo così onerosa la manutenzione relativa alla sostituzione periodica delle batterie e pregiudicando l’affidabilità generale del sistema di contabilizzazione.L'effetto Peltier può essere sfruttato per alimentare un contatore di calore in virtù della differenza di temperatura esistente tra il fluido termovettore dell’impianto, che scorre nel corpo radiante monitorato, e l’ambiente riscaldato. Si può così produrre l'energia elettrica necessaria a rendere il contatore un dispositivo stand-alone autoalimentato, senza bisogno di connessioni alla rete elettrica o di batterie chimiche da sostituire periodicamente. La minore manutenzione richiesta può così favorire la diffusione della contabilizzazione dell'energia per il riscaldamento, che è fondamentale per incentivare gli utenti al risparmio energetico.Il presente studio si è focalizzato sulle strategie di dimensionamento ed ottimizzazione del microgeneratore in oggetto, utilizzando a tal scopo metodologie di modellazione a parametri concentrati e considerando diverse configurazioni del dispositivo. Il progetto è stato sviluppato prendendo a riferimento componentistica commerciale ovunque possibile, in modo da garantire ridotti costi di fabbricazione ed affidabilità adeguata.
2007
- Assessment of flow distribution in a roof with forced ventilation by infrared thermography
[Relazione in Atti di Convegno]
L., Tarozzi; E., Caffagni; Muscio, Alberto
abstract
An effective approach to roof ventilation has been developed. It is aimed at mitigating summer overheating of inhabited rooms located immediately below the roof. The air flows in a ventilation layer made of parallel ducts and built between roof coverings and insulation, thus subtracting heat from the roof structure. It is then collected by a header and eventually discharged into the atmosphere by a extraction fan. The problem of obtaining a homogeneous flow distribution in the ventilation layer is solved by a very simple regulation mechanism, placed in the header and adjusted on site. The adjustment procedure is based on measurements of surface temperature distribution performed by an infrared camera.
2007
- Experimental tests of dropwise cooling on infrared-transparent media
[Articolo su rivista]
L., Tarozzi; Muscio, Alberto; Tartarini, Paolo
abstract
The present work is aimed at analyzing the cooling of hot solid surfaces induced by liquid droplets. In particular, the study is focused on the non-intrusive measurement of the transient contact temperature between impinging droplets and hot solid surfaces.An experimental apparatus was built and set up in order to approach the non-trivial problem of the measurement of a solid–liquid interface temperature after droplet impingement. The solid–liquid interface temperature was monitored from below through a transparent-to-infrared material. That material had been coated with a very thin layer of high-emissivity, opaque paint on its upper side, so that it could effectively respond to the infrared camera located below.The paper reports the main results that have been collected to date, with particular regard to the approaches used to coat the transparent solid. Some considerations are also expressed about the effectiveness of the proposed method and about the improvements thatare currently being implemented to get new and more accurate interface temperature measurements.
2007
- Investigation of surface cooling by droplet evaporation with IR infrared thermography
[Relazione in Atti di Convegno]
L., Tarozzi; Muscio, Alberto; Tartarini, Paolo
abstract
In the present work infrared thermography is used to analyze the cooling effect of a hot solid surface induced by liquid droplets. In particular water droplets are released onto a BaF2 disk heated by radiation from above; the interface temperature is measured from below by means of an AVIO TVS500 infrared camera, carrying a micro-bolometric FPA sensor which operates in the long wave spectral range. The study is focused on the non-intrusive technique used to measure the transient temperature at the interface between impinging droplets and hot surface; experimental data are reported and compared with theoretical results.
2007
- Investigation of surface cooling by droplet evaporation with IR thermography
[Relazione in Atti di Convegno]
L., Tarozzi; Muscio, Alberto; Tartarini, Paolo
abstract
In the present work infrared thermography is used to analyze the cooling effect of a hot solid surface induced by liquid droplets. In particular water droplets are released onto a BaF2 disk heated by radiation from above; the interface temperature is measured from below by means of an AVIO TVS500 infrared camera, carrying a micro-bolometric FPA sensor which operates in the long wave spectral range. The study is focused on the non-intrusive technique used to measure the transient temperature at the interface between impinging droplets and hot surface; experimental data are reported and compared with theoretical results.
2007
- Misure di diffusività termica mediante il metodo di Angstroem applicato a campioni termicamente corti
[Relazione in Atti di Convegno]
Muscio, Alberto
abstract
Il metodo di Angstroem e le sue diverse varianti prevedono che la diffusività termica di un materiale venga determinata sulla base delle modalità di propagazione periodica stabilizzata di onde termiche in un campione con elevato allungamento. In generale, si adottano condizioni di lavoro tali da poter considerare il campione virtualmente infinito, cioè tali che le onde termiche vengano smorzate completamente prima di raggiungere l'estremità del campione opposta a quella a cui sono state applicate. In questo modo, la formulazione matematica del problema rimane relativamente semplice e se ne possono ricavare agevoli procedure di stima della diffusività.La condizione di campione termicamente infinito a volte non può essere raggiunta, specialmente se si devono analizzare materiali molto conduttivi e disponibili in campioni di dimensioni ridotte. Inoltre, i fenomeni di riflessione delle onde termiche che si instaurano in un campione termicamente corto possono essere proficuamente sfruttati per filtrare gli effetti dello scambio termico tra superfici del campione ed ambiente di prova. Per questi motivi, si è studiato un modello matematico per la condizione di campione termicamente corto e si sono da questo sviluppate procedure specifiche per la stima della diffusività.Nel presente articolo si fornisce una presentazione dettagliata del modello matematico sviluppato e dei risultati sinora ottenuti.
2007
- Ricerca di mine mediante termografia infrarossa: analisi dell’influenza dell’umidità superficiale
[Relazione in Atti di Convegno]
L., Tarozzi; Muscio, Alberto; Corticelli, Mauro Alessandro; Barozzi, Giovanni Sebastiano
abstract
Il problema dell’individuazione di una mina antiuomo sotterrata è estremamente complesso e di difficile soluzione. Attualmente, la ricerca manuale mediante sondino ad asta costituisce l’approccio più efficace per le attività di bonifica di un’area minata, ma comporta tempi estenuanti e pericoli notevoli per il personale addetto. È quindi evidente la necessità di sviluppare tecniche alternative. Fra queste, si presenta molto interessante la ricerca mediante termografia infrarossa.Questo studio si inserisce in un filone di ricerca da tempo avviato presso il Dipartimento di Ingegneria Meccanica e Civile di Modena, vertente sullo sviluppo di metodologie di indagine che consentano di prevedere ed incrementare l’affidabilità della ricerca di mine antiuomo tramite termografia all’infrarosso. In questa sede, l’analisi ha riguardato l’effetto dell’umidità superficiale del suolo sulla segnatura termica della mina, cioè sul contrasto tra temperatura superficiale del terreno sopra la mina e temperatura superficiale del terreno circostante. Si è a tal scopo impiegato un apparato sperimentale sviluppato nel corso di precedenti attività di ricerca, che consente di riprodurre con scala spaziale e temporale ridotta il comportamento termico un campo minato e le condizioni ambientali che lo caratterizzano. Gli esperimenti svolti hanno mostrato che l’umidificazione del terreno può incrementare notevolmente la segnatura termica della mina e può essere quindi sfruttata per aumentare le probabilità di individuazione.
2007
- Scale reduction in modeling landmine detection by IR Termography
[Articolo su rivista]
L., Tarozzi; Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
A method has been proposed to reproduce in the laboratory experiments of infrared landmine detection with reduced length- and time-scale. In this work, the method is verified experimentally. Models of landmines are purposely built by a rapid prototyping technique. The surface response of the soil-landmine system is then monitored by an infrared camera. Preliminarily, the response measured above full-scale models is cross-checked against that measured above actual landmines. Full-scale and reduced-scale models are subsequently tested outdoors and in the laboratory, respectively. The measured distribution and time-evolution patterns of surface temperature are eventually compared, in order to assess the reliability of the scale reduction method.
2007
- Solar reflecting tile coverings for traditional South-European Buildings
[Relazione in Atti di Convegno]
L., Tarozzi; Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
An effective solution to summer overheating of buildings is provided by “cool roofs”. These are building coverings with high reflectance to solar radiation and high emittance in the infrared range. They have been investigated extensively in the U.S.A., where certification procedures have already been developed by independent bodies, and certified products are commercially available.Common cool roof products have white or very light colors. As a result, they are difficult to use in most ancient or traditional south-European buildings, which typically have steep-slope roofs covered by red clay tiles. On the other hand, in places like the historical centers of Italian and other Mediterranean cities the rooms immediately below the roof are often inhabited, so that the relatively low solar reflectance of tile coverings makes summer overheating a major problem. This can be effectively addressed by using tiles coated with “cool colors”, that is colors with the same spectral response of clay tiles in the visible, but highly reflecting in the near infrared range, which includes about half of solar radiation. Cool colors can yield the same visible aspect of common building surfaces, but much higher solar reflectance.In the aim of verifying the potential of cool color tile coverings, an investigation was started at the DIMeC. Materials for cool color coating were analyzed in the laboratory, verifying their radiation properties as a function of composition and pigment content. Prototypes of red roof tiles have been built using easily available materials with solar reflectance almost twice that of conventional tiles.
2007
- Thermographic analysis of flow distribution in compact heat exchangers for a Formula 1 car
[Articolo su rivista]
E., Caffagni; Levoni, Paolo; M., Piraccini; Muscio, Alberto; Corticelli, Mauro Alessandro; Barozzi, Giovanni Sebastiano
abstract
A non-intrusive approach is investigated to calculate the internal flow distribution in heat exchangers. In particular, the liquid flow rate can be determined in each tube of an air-liquid finned-tube heat exchanger. A purposely designed test bench impresses a sudden change of temperature of the liquid flowing through the heat exchanger. The thermal transient that follows is monitored by a thermographic camera. This measures the rise of surface temperature along each tube. The temperature evolution pattern is then correlated to the flow rate in the tube by simple mathematical processing. The heat exchanger is tested in still air. Modification is not required. The approach is tested on heat exchangers for a F1 race car, with encouraging results. (c) 2006 Elsevier B.V. All rights reserved.
2006
- CFD-based thermal analysis of a complex shape car audio amplifier shell
[Relazione in Atti di Convegno]
Levoni, Paolo; E., Caffagni; Muscio, Alberto; F., Bruschi
abstract
The work is aimed at presenting a successful case of complex industrial application of thermal-fluid dynamics CFD analysis on a finned aluminium shell for car audio amplifiers designed by ASK Industries S.p.A.Heat transfer phenomena taking place in such a device include conduction along the shell body, convective and radiative heat transfer between the shell external surfaces and the ambient air. Complexities (MI PIACE POCO) of physical and geometrical nature prevent simplified analytical or semi-empirical models from being applied. Hence, only an accurate CFD model, realistically reproducing the exact shape of the device and all heat transfer mechanisms involved in the system, can supply information correct and useful for improvement and optimization of the shell design. 3D steady-state simulations using the industrial Navier-Stokes CFD code Fluent 6.2 (© Fluent Inc.) were performed on a Linux cluster at the DIMeC.The simulations were cross-checked with surface temperature patterns acquired via infrared thermography. The comparison shows an excellent agreement between experimental and CFD temperature data and demonstrates a very good reliability of the numerical approach.
2006
- Experiments on scale reduction in infrared landmine detection
[Relazione in Atti di Convegno]
Muscio, Alberto; L., Tarozzi; Corticelli, Mauro Alessandro
abstract
A method has been proposed to reproduce in the laboratory experiments of infrared landmine detection with reduced length- and time-scale. In this work, the method is verified experimentally.Models of landmines are purposely built by a rapid prototyping technique. The surface response of the soil-landmine system is then monitored by an infrared camera. Preliminarily, the response measured above full-scale models is cross-checked against that measured above actual landmines. Full-scale and reduced-scale models are subsequently tested outdoors and in the laboratory, respectively. The measured distribution and time-evolution patterns of surface temperature are eventually compared, in order to assess the reliability of the scale reduction method.
2006
- Experiments on scale reduction in infrared landmine detection
[Abstract in Atti di Convegno]
Muscio, Alberto; L., Tarozzi; Corticelli, Mauro Alessandro
abstract
A method has been proposed to reproduce in the laboratory the heating and cooling cycles of a soil with a buried land-mine. The method allows the length-scale and time-scale of the experiments to be drastically decreased. This is achieved by dimensional analysis of the thermal problem. A preliminary confirmation of the used approach was obtained with simplified tests [1-3].In the present work, the method is verified experimentally. Models of different types of land-mine are produced for this purpose. Full-scale and scaled-down models are built by a rapid prototyping technique, using materials with thermal properties similar to those of the actual land-mines.The response of the soil surface is monitored during the thermal cycles by an infrared camera. Preliminarily, the surface response measured above full-scale models is cross-checked against that measured above actual land-mines. Full-scale and scaled-down models are then tested outdoors and in the laboratory, respectively. The measured distribution and time-evolution patterns of surface temperature are eventually compared, in order to assess the reliability of the scale reduction method.
2006
- Study of thermal conductivity in refractory materials by means of a Guarded Hot Plate Apparatus", Milan, Italy, 11-15 December 2006, Abstract Book, p. 108 (2006).
[Abstract in Atti di Convegno]
D. N., Boccaccini; Veronesi, Paolo; Muscio, Alberto; Leonelli, Cristina
abstract
.
2006
- Un dispositivo compatto per la misura della diffusività termica mediante il metodo di Angstroem
[Relazione in Atti di Convegno]
G., Sartori; L., Tarozzi; Muscio, Alberto
abstract
Un dispositivo compatto per la misura della diffusività termica di materiali solidi, basato sul metodo di Angstroem, è in corso di sviluppo presso il Dipartimento di Ingegneria Meccanica e Civile di Modena.Il metodo di Angstroem prevede che la diffusività termica del materiale venga determinata sulla base delle modalità di propagazione di onde termiche periodiche stabilizzate in un campione con elevato allungamento. Il dispositivo in esame si basa su una particolare modifica del metodo di Angstroem, nella quale le onde termiche sono prodotte tramite una sorgente a cella di Peltier in grado di generare una sinusoide di temperatura perfetta e con valore medio di oscillazione impostabile a piacere, eventualmente pari al valore ambiente. Tale approccio consente una preparazione ed uno svolgimento degli esperimenti non particolarmente onerosi, nonché procedure di analisi dei dati relativamente semplici e, verosimilmente, alla portata di operatori senza preparazione specifica.Per rendere agevole e user-friendly il dispositivo allo studio, si è perseguita la massima integrazione delle routine di gestione degli esperimenti e di analisi dei dati, implementate nell’ambiente di programmazione LabView di National Instruments.In questo articolo si fornisce una presentazione dettagliata del dispositivo e dei risultati preliminari ottenuti su campioni precedentemente caratterizzati mediante tecniche e sistemi differenti.
2005
- Dropwise cooling: experimental tests on infrared-transparent media
[Relazione in Atti di Convegno]
L., Tarozzi; Muscio, Alberto; Tartarini, Paolo
abstract
The present work is aimed at analyzing the cooling of hot solid surfaces induced by liquid sprays. In particular, the study is focused on the measurement of the transient contact temperature between impinging droplets and hot solid surfaces.An experimental apparatus was built and setup in order to approach the non-trivial problem of the non-intrusive measurement of a solid-liquid interface temperature after droplet impingement. The solid-liquid interface temperature was monitored from below through a transparent-to-infrared, zero-emissivity material. That material had been coated with a very thin layer of high-emissivity, opaque paint on its upper side, so that it could effectively respond to the infrared camera located below.The experiences collected up to now are described, with particular regard to the approaches used to coat the transparent solid. The results of a few preliminary tests are also reported here, together with considerations about the effectiveness of the proposed method and about the improvements that are currently being implemented to get new and more accurate interface temperature measurements. The obtained results are comparable with the predictions of the theoretical contact temperature equation, which is available in literature.
2005
- I cool roofs, una soluzione innovativa per il risparmio energetico in edilizia
[Relazione in Atti di Convegno]
Barozzi, Giovanni Sebastiano; Corticelli, Mauro Alessandro; Muscio, Alberto; Tartarini, Paolo
abstract
I cool roofs sono tetti contraddistinti da elevata capacità di riflettere l’irradiazione solare incidente e, al contempo, di emettere energia termica nell’infrarosso. Essi possono fornire un’efficace soluzione al problema del surriscaldamento estivo dei singoli edifici e delle grandi aree urbane.In California e in altri Stati degli U.S.A. i cool roofs sono da molti anni oggetto di analisi tecnico-economiche estensive e, più recentemente, di attività di certificazione e regolamentazione. In Italia, invece, sebbene le condizioni climatiche di buona parte della penisola siano tali da rendere conveniente l’installazione di cool roofs, questi sembrano sconosciuti ai più. Studi in materia sono stati perciò avviati dal Dipartimento di Ingegneria Meccanica e Civile di Modena.In questa relazione si illustra il funzionamento dei cool roofs dal punto di vista fisico. In particolare, si analizzano gli effetti che le diverse proprietà emissive hanno sulle temperature raggiunte dal tetto e sul calore che lo attraversa. Si delineano inoltre i principali programmi di attestazione delle proprietà e di incentivazione avviati degli U.S.A. e la situazione di mercato.
2005
- Potential of Thermal Engine Encapsulation on Automotive Diesel Engines
[Relazione in Atti di Convegno]
Mattarelli, E.; Muscio, A.
abstract
Thermal Engine Encapsulation (TEE) is a technique for reducing heat loss from an engine after it has been switched off, in order to get a warmer re-start. This practice yields benefits in terms of fuel economy, emissions and wear, especially for vehicles used for short journeys in cold weather and with engines warming up slowly. In this study, the encapsulation of a small automotive diesel engine is investigated by means of theoretical and experimental analyses. In particular, the influence of oil temperature on brake specific fuel consumption and emissions is calculated. Furthermore, the thermal behavior of the engine has been simulated by a lumped-capacitance model, in order to assess the correlation between encapsulation thickness and cool-down time. Finally, the 0-D thermal model and the 1-D engine model have been coupled in order to predict the influence of engine cranking temperature on fuel consumption and pollutant emissions, considering a B-class vehicle running a short journey (15 minutes) at medium speed and load and very low external temperature (0emDC).
2005
- Potential of thermal engine encapsulation on automotive diesel engines - SAE Technical Paper Series 2005-20-067
[Relazione in Atti di Convegno]
Muscio, Alberto; Mattarelli, Enrico
abstract
Thermal Engine Encapsulation (TEE) is a technique for reducing heat loss from an engine after it has been switched off, in order to get a warmer re-start. This practice yields benefits in terms of fuel economy, emissions and wear, especially for vehicles used for short journeys in cold weathers and with engines warming up slowly.In this study, the encapsulation of a small automotive Diesel engine is investigated by means of theoretical and experimental analyses. In particular, the influence of oil temperature on brake specific fuel consumption and emissions is calculated. Furthermore, the thermal behavior of the engine has been simulated by a lumped-capacitance model, in order to assess the correlation between encapsulation thickness and cool-down time.Finally, the 0-D thermal model and the 1-D engine model have been coupled in order to predict the influence of engine cranking temperature on fuel consumption and pollutant emissions, considering a B-class vehicle running a short journey (15 minutes) at medium speed and load and very low external temperature (0°C).
2005
- Radiative properties of Surfaces and energy saving in buildings: the cool roofs
[Relazione in Atti di Convegno]
Barozzi, Giovanni Sebastiano; Corticelli, Mauro Alessandro; Muscio, Alberto; L., Tarozzi; Tartarini, Paolo
abstract
Cool roofs are building coverings having high reflectance to solar radiation and high emittance in the infrared range. They can provide an effective solution to building overheating during hot seasons.In the U.S.A. the cool roofs have been investigated extensively. Certification procedures have also been developed by independent bodies, and certified roof products are commercially available.In the aim of verifying the potential of cool roof technologies for the Italian climate, an investigation was started at the Dept. of Mechanical and Civil Engineering at Modena.Early results are presented for an experimental cool roof. The work is completed with an analysis of the thermal behavior of a typical low-slope roof and a brief review of existing certification programs and commercially available products.
2005
- Raffreddamento di superfici lisce mediante array di gocce
[Relazione in Atti di Convegno]
A., Barba; Muscio, Alberto; M., Spiga
abstract
Il presente lavoro è rivolto allo studio sperimentale del raffreddamento di superfici metalliche lisce, causato dalla deposizione o impatto di gocce singole o di un array composto da due gocce di liquido disposte in parallelo. Lo scopo è stato quello di ottenere immagini e dati sperimentali sui meccanismi di evaporazione di gocce di acqua distillata su superficie orizzontale in acciaio inossidabile a diverse temperature e per numeri di Weber differenti (cioè per differenti valori dell'altezza di rilascio delle gocce). La piastra metallica è riscaldata a valori di temperatura superiori alla temperatura di vaporizzazione dell'acqua, mediante un flusso di olio diatermico che scorre inferiormente alla superficie liscia di impatto. Attenzione è stata rivolta alla determinazione dell'angolo di contatto, dell'area bagnata dalle gocce, dei tempi di evaporazione e della temperatura della superficie solida in funzione del tempo. E' stata inoltre studiata l'interazione termica tra due gocce deposte a distanze differenti sulla superficie metallica. Nell'indagine è stata utilizzata la tecnica della termografia nell'infrarosso che permette di effettuare misure di temperatura superficiale in modo non invasivo. I risultati sono mostrati in numerosi grafici, ottenuti per diversi valori della distanza tra le due gocce e per diversi valori del numero di Weber.
2005
- Rilievi di velocità in regime di convezione naturale mediante tecnica "pulsed doppler ultrasound" in un cavità contenente una sorgente termica
[Relazione in Atti di Convegno]
Barozzi, Giovanni Sebastiano; Muscio, Alberto; L., Tarozzi
abstract
Oggetto del presente studio è l’analisi sperimentale del campo di moto in regime di convezione naturale all’interno di una cavità parallelepipeda contenente un fluido, in cui è immersa una sorgente termica orizzontale di forma cilindrica. Per la misura della velocità del fluido si utilizza la tecnica “Ultrasound Pulsed Doppler Velocimetry” (UPDV), che permette di effettuare misure non intrusive e, in linea di principio, di ricostruire l’intero campo di moto. L’applicabilità della tecnica non è ancora stata verificata a fondo in regimi di convenzione naturale.Si descrivono in questo lavoro l’apparato sperimentale che è stato realizzato, la procedura di rilevazione della velocità e quella di ricostruzione del campo di moto su una sezione verticale mediana della cavità parallelepipeda. Le principali criticità poste dalla tecnica di misura e dal particolare ambito di applicazione vengono evidenziate attraverso la presentazione dei risultati sperimentali ottenuti. Infine, si confrontano i risultati sperimentali con quelli forniti da simulazioni numeriche CFD.
2005
- Tecniche fototermiche e termografiche per la misura della diffusività
[Relazione in Atti di Convegno]
P. G., Bison; F., Cernuschi; E., Grinzato; S., Marinetti; Muscio, Alberto
abstract
La collaborazione di tre laboratori ha permesso di utilizzare differenti tecniche di misura della diffusività termica, alcune fototermiche, altre termografiche, applicandole ad un campione di acciaio AISI 304. Lo scopo è quello di mettere a confronto le tecniche termografiche con quelle fototermiche, quest'ultime considerate di riferimento, al fine di utilizzare in campo le prime con uno specificato grado di attendibilità. Si descrive brevemente ogni singola tecnica e alla fine viene compilata una tabella di risultati con la stima dell'errore, in modo da dare una valutazione oggettiva dell’affidabilità delle varie misure.
2005
- Thermographic analysis of flow distribution in compact heat exchangers for a Formula 1 car
[Abstract in Atti di Convegno]
E., Caffagni; Levoni, Paolo; Muscio, Alberto; Corticelli, Mauro Alessandro; Barozzi, Giovanni Sebastiano; M., Piraccini
abstract
THERMOGRAPHIC ANALYSIS OF FLOW DISTRIBUTIONIN COMPACT HEAT EXCHANGERS FOR A FORMULA 1 CAR
2005
- Thermographic measurement of the solid-liquid interface temperature through infrared-transparent media
[Relazione in Atti di Convegno]
Tartarini, Paolo; Muscio, Alberto; L., Tarozzi
abstract
A new, non-intrusive method is proposed to measure the solid-liquid contact temperature duringdropwise evaporative cooling. The droplets are deposited onto a material which is transparentin the infrared spectral band. The interface temperature can thus be measured through the solidmaterial by a thermographic camera. The transparent tile is coated with a very thin layer ofhigh-emissivity, opaque paint on its upper side, so that it can effectively respond to the infraredcamera below.
2004
- Analisi termografica delle maldistribuzioni in uno scambiatore di calore per vetture di Formula 1
[Relazione in Atti di Convegno]
M., Piraccini; Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
In uno scambiatore di calore compatto liquido-aria, la portata di liquido deve distribuirsi uniformemente tra le cannette parallele che costituiscono la massa radiante dello scambiatore. Ciò si ottiene adottando collettori d’immissione e di estrazione del liquido opportunamente conformati, la cui progettazione può essere oggi effettuata, con elevato livello di dettaglio, mediante simulazione numerica. La verifica sperimentale della qualità del progetto è però impegnativa, poiché è possibile formulare valutazioni quantitative sull’omogeneità di distribuzione del liquido refrigerante soltanto ricorrendo a complesse procedure sperimentali ed alla realizzazione di prototipi dello scambiatore opportunamente preparati. Per questo motivo, gli studi sperimentali sono generalmente limitati alla misura di parametri di prestazione globali come, ad esempio, l’efficienza complessiva dello scambiatore.In questo lavoro si presenta una tecnica di misura non intrusiva che consente di stimare, senza dover apportare modifiche allo scambiatore analizzato o eseguire elaborazioni sofisticate dei dati sperimentali, la portata in ognuna delle cannette della massa radiante di uno scambiatore liquido-aria a fascio tubiero alettato. La tecnica è basata sull’analisi del transitorio di riscaldamento che consegue all’immissione nello scambiatore, inizialmente a temperatura ambiente, di una portata di liquido a temperatura molto più elevata. Infatti, la velocità di riscaldamento della parete delle varie cannette, rilevabile mediante termografia infrarossa, può essere correlata alla velocità e, quindi, alla portata del liquido che fluisce all’interno delle cannette stesse.
2004
- Analysis of the impact of surface heat transfer on a new modification of the Angstroem’s method
[Relazione in Atti di Convegno]
C., Bussi; Corticelli, Mauro Alessandro; Muscio, Alberto
abstract
A new modification of the Angstroem’s method for thermal diffusivity measurement has been developed. This relies on the propagation of harmonic thermal waves with mean value equal to the ambient temperature. The diffusivity is evaluated by relatively simple processing of temperature data, acquired by infrared thermography.The evaluation is based on a mathematical model, in which the heat transfer coefficient at the specimen surface is assumed to be constant. This work is aimed at verifying that assumption. In particular, the effects of natural convection in air are investigated theoretically by numerical simulation. A strategy to improve the test procedure is finally outlined.
2004
- CFD ananlysys onf the impact of convection in a new modeification of the Ångstroem’s method
[Relazione in Atti di Convegno]
Levoni, Paolo; Muscio, Alberto; Corticelli, Mauro Alessandro; Barozzi, Giovanni Sebastiano
abstract
measurement was developed. Its novelty is that harmonic thermal waves with mean value equal to the ambient temperature are induced in the specimen by a purposely developed source. This allows estimating the diffusivity by relatively simple processing of surface-temperature data.The estimate is based on a mathematical model, in which the unknown coefficient of surface heat transfer is assumed to be uniform and constant. The coefficient can thus be eliminated by combining information from amplitude decay and phase velocity of the thermal waves.This work is aimed at verifying the assumption of uniform and constant heat transfer coefficient. A parametric analysis is performed by CFD simulation of the test system.
2004
- Experiments of thermographic landmine detection with reduced size and compressed time
[Articolo su rivista]
Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
Infrared thermography is a promising technique for the detection of buried landmines. Its effectiveness is not yet satisfactory, but it can presumably be improved by means of proper data-processing tools. The development of these tools, however, necessitates large amounts of reference data. On-field experiments are required to generate reference data, but they can be very demanding, since it is arduous to control the thermal problem outdoors and all over a whole day. In view of that, a method was developed to reproduce in the laboratory, with reduced size and duration, experiments of thermographic mine detection. The method was devised by the dimensional analysis of the governing equations, for which a generalized formulation is presented, and it was implement by a purposely built apparatus, which allows taking into account the directional properties of the solar radiation. A few test cases with reduced scale are reported here, to show the potential of the proposed experimental approach.
2004
- Influenza della convezione e dell'irraggiamento nella misura della diffusività termica mediante una nuova variante del metodo di Angstroem
[Relazione in Atti di Convegno]
C., Bussi; Muscio, Alberto; Corticelli, Mauro Alessandro; Barozzi, Giovanni Sebastiano
abstract
Una nuova variante del metodo di Angstroem consente di stimare, attraverso un’analisi relativamente semplice di misure termografiche nell’infrarosso, la diffusività termica di un materiale solido. La diffusività è correlata alle modalità con cui un’oscillazione termica si propaga in un campione del materiale in esame. La semplicità dell’analisi è conseguenza del fatto che l’oscillazione termica applicata al campione, prodotta tramite un dispositivo appositamente sviluppato, è perfettamente armonica e con valore medio pari alla temperatura ambiente.La procedura di stima della diffusività è basata su una formulazione matematica, in cui si assume costante ed uniforme il coefficiente di scambio termico sulle superfici del campione esposte all’aria. Sotto tale ipotesi, la determinazione del coefficiente di scambio termico, che è in generale incognito, è superflua ai fini della determinazione della diffusività.In questo lavoro si riportano i risultati di un’analisi parametrica dei fenomeni di scambio termico superficiale, effettuata tramite metodi numerici e volta, da una parte, a verificare l’ipotesi di uniformità del coefficiente di scambio termico, dall’altra, ad investigare approcci atti a minimizzare l’impatto dei fenomeni convettivi sull’accuratezza della stima della diffusività.
2004
- Land-mine detection by infrared Thermography: reduction of the size and duration of the experiments
[Articolo su rivista]
Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
The effectiveness of infrared thermography applied to the detection of abandoned land mines is not yet acceptable. It can probably be improved, however, by computerized processing of the thermal images. This requires reference data, which must be provided mainly by experiments. A method is presented here, by which the heating and cooling cycles of a soil with a buried land mine can be replicated with reduced size and duration. The reference data acquired in the laboratory can be associated to realistic on-field tests by simply stretching the space and time scales. This will permit to reproduce indoors, quickly and effortlessly, the outdoor conditions of any place where the detection of buried land mines must be performed. In this paper, the general thermal problem is described, and the proposed method is comprehensively explained. The results of computer simulations and some laboratory tests are finally reported for validation.
2004
- The problem of the contact temperature in droplet-solid heat transfer: experimental analysis
[Relazione in Atti di Convegno]
Muscio, Alberto; G., Tambascia; Tartarini, Paolo
abstract
The present work is aimed at analyzing the cooling of hot solid surfaces induced by liquid sprays. In particular, the study is focused on the measurement of the transient contact temperature between impinging droplets and hot solid surfaces.An experimental apparatus was built and setup in order to approach the non-trivial problem of the non-intrusive measurement of a solid-liquid interface temperature after droplet impingement. The solid-liquid interface temperature was monitored from below through a transparent-to-infrared, zero-emissivity material. That material had been coated with a very thin layer of high-emissivity, opaque paint on its upper side, so that it could effectively respond to the infrared camera located below.The experiences collected up to now are described, with particular regard to the approaches used to coat the transparent solid. The results of a few preliminary tests are also reported here, together with considerations about the effectiveness of the proposed method and about the improvements that are currently being implemented to get new and more accurate interface temperature measurements. The obtained results are comparable with the predictions of the theoretical contact temperature equation, which is available in literature.
2004
- Thermal diffusivity measurement in slabs using harmonic and one-dimensional propagation of thermal waves
[Articolo su rivista]
Muscio, Alberto; P. G., Bison; S., Marinetti; E., Grinzato
abstract
The development of a novel approach to the well-known Angstrom´s method for the measurement of the thermal diffusivity is reported. In this method, the diffusivity is determined from the damping and the phase shift of a periodic thermal signal during its propagation along the specimen. The propagation can be easily monitored by infrared thermography. In general, a non-contact source is used to apply the signal. In the present work, however, a direct-contact source is employed, with a temperature-oscillation signal supplied on a portion of one of the two main surfaces of the specimen, where a homogeneous contact can be yielded by using a proper contact pressure. Such practice implies that the measures of surface temperature can be used to estimate the diffusivity only beyond a certain distance from the source, where the wave-front of the temperature oscillation within the specimen becomes plane and perpendicular to the main surfaces. This distance is investigated here, to establish a general rule for the performance of the experiments. A thermoelectric device based on the Peltier effect is employed as the thermal source. The main difficulty about its use is to obtain a perfectly harmonic and well-balanced thermal signal. This is necessary to avoid a complex processing of the experimental data, and it can be achieved by supplying a current with a properly-chosen time-evolution pattern. Such an approach, which is built upon previous work, is here enhanced by improving the underlying analytical model.
2003
- Analisi CFD dei campi di moto e di temperatura dell'aria in una cattedrale
[Relazione in Atti di Convegno]
Corticelli, Mauro Alessandro; Muscio, Alberto; Tartarini, Paolo
abstract
Nel presente lavoro viene proposta un’indagine teorica e numerica sul campo di moto e sulla distribuzione della temperatura dell’aria all’interno della National Shrine of the Immaculate Conception, una cattedrale di imponenti proporzioni situata nel campus della Catholic University of America a Washington, D.C., U.S.A.Lo studio è finalizzato a valutare differenti modalità di riscaldamento dell’ambiente interno della cattedrale, e trae motivazione dal gran numero di edifici per il culto che presentano dimensioni e caratteristiche simili e dall’esigenza diffusa di ottimizzarne gli impianti di climatizzazione, in termini di benessere delle persone e di risparmio energetico.Dal punto di vista teorico, si propone un’analisi adimensionale del problema, basata sul numero di Rayleigh. Le simulazioni numeriche sono effettuate mediante il codice CFD industriale Fluent, prodotto da Fluent Inc., Lebanon, N.H., U.S.A.
2003
- Measurement of thermal diffusivity by propagation of thermal waves: a new modification of the Ångström method
[Relazione in Atti di Convegno]
Muscio, Alberto; P. G., Bison; S., Marinetti; E., Grinzato
abstract
A new technique for measurement of the thermal diffusivity is presented here. The technique is a modification of the well-known Ångström’s method, which relies on the steady-periodic propagation of thermal waves along a specimen to estimate the diffusivity. The novelty of the proposed modification is that harmonic thermal waves with mean value equal to the ambient temperature are induced in the specimen by means of a purposely developed source, based on the Peltier effect. This allows estimating the diffusivity by relatively simple processing of surface-temperature data, acquired by infrared thermography.The mathematical formulation of the thermal problem is described here, together with the experimental procedure and the apparatus by which the most proper thermal signal can be achieved. A cross comparison with other measurement techniques is finally reported.
2003
- Mine detection by infrared thermography: reduction of size of the experiments
[Abstract in Atti di Convegno]
Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
A very promising technique for the detection buried land-mines is infrared thermography. In particular, the presence of a mine can be associated to a specific pattern in the temperature of the soil surface measured by a videothermographic camera. The pattern is induced by the interaction of the daily heating and cooling cycles with the thermal anomaly introduced in the ground by the mine.The specific effectiveness of the thermographic mine detection can be increased by exploiting computerized data-processing tools such as neural-networks, genetic algorithms, or the fusion of dual-band data, to enhance and identify the thermal signature of the mine. The development and ‘training’ of these tools, however, as well as the optimization of the detection equipment and procedure, require a large amount of reference data.Simulations are powerful tools to generate reference data, as they allow fast and inexpensive parametrical analyses. Unfortunately, computer models cannot take care of all the variables influencing a real-world problem and, furthermore, they need a proper calibration. On the other hand, performing parametrical analyses by on-field experiments can be long and challenging, since in an outdoor test environment and along the 24-hour long day period it is arduous to control selectively the phenomena that influence the thermal problem, especially the weather conditions.In view of this, the main objective of the present work is to develop a method by which the cycles of heating and cooling of the soil can be replicated in the laboratory with a reduced scale, either in time or in space, but obtaining measures that can be directly correlated to realistic on-field tests. The result is sought through the dimensional analysis of the equations governing the thermal problem, and it is verified by computer simulations and experiments.
2003
- Ricerca di mine mediante termografia infrarossa: riduzione della scala degli esperimenti
[Relazione in Atti di Convegno]
L., Tarozzi; Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
Una tra le tecniche più promettenti per la ricerca di mine è la termografia infrarossa. Mediante metodi termografici è infatti possibile rilevare l’anomalia che si produce nella distribuzione di temperatura in superficie per effetto dell’interazione dei cicli termici giornalieri e della discontinuità introdotta da un mina sotterrata.Questo lavoro è focalizzato sullo sviluppo di strumenti di indagine che consentano di prevedere ed incrementare l’affidabilità della ricerca di mine mediante termografia infrarossa. Uno di questi è costituito da un modello matematico del comportamento termico del terreno e della mina, in quanto esso permette di compiere studi estensivi con tempi e costi relativamente ridotti. La sua messa a punto è quindi un obiettivo di questa ricerca.D’altra parte, un modello non è da solo sufficiente allo svolgimento di un’indagine completa ed esaustiva, in quanto non può contemplare tutte le variabili che influenzano il problema reale e, inoltre, richiede un’adeguata calibrazione. In questa ottica, l’obiettivo primario del presente lavoro è lo sviluppo di un metodo atto a consentire la riduzione della scala del problema nel tempo e nello spazio, al fine di rendere più veloce e semplice la pratica sperimentale. In particolare, si vogliono scalare il periodo caratteristico, che nella realtà è pari a ventiquattro ore, e le dimensioni dell’ambiente di prova, ottenendo tuttavia risultati correlabili direttamente con il caso reale. Il fine ultimo è riprodurre rapidamente e agevolmente in laboratorio le condizioni ambientali di qualsiasi luogo in cui si debbano ricercare mine mediante termografia infrarossa.
2003
- Theoretical and Numerical Study on Dropwise Cooling under Nucleate Boiling Conditions
[Relazione in Atti di Convegno]
C., Bussi; Muscio, Alberto; Tartarini, Paolo
abstract
In this work, a theoretical model has been formulated and a numerical code has been developed to analyze the cooling effect induced by liquid droplets during single-phase evaporation and nucleate boiling regime on high temperature solid surfaces.The model is based on a numerical integration of the energy and mass conservation equations in the solid and the liquid domain. In terms of geometry discretization, a cylindrical coordinate system is used, and the differential equations are modeled on an axis-aligned half plane. Evaporation of liquid is reproduced at either the solid-liquid or the liquid-air interfaces.The non-linear system of partial differential equations is discretized using an iterative, second-order in time and space, semi-implicit scheme. A fast sparse solver is used to obtain energy and mass variations with respect to time. Experimental results are finally employed to tune and validate the model.
2002
- Caratterizzazione del funzionamento di dispositivi per ventilazione forzata mediante termografia infrarossa
[Relazione in Atti di Convegno]
G., Severi; Muscio, Alberto; Corticelli, Mauro Alessandro
abstract
L’impiego crescente di dispositivi attivi di ventilazione in elettrodomestici ed apparecchiature elettroniche di largo consumo rende sempre più interessante lo sviluppo e la messa a punto di metodi di studio che permettano di determinarne ed ottimizzarne le prestazioni – metodi che devono però risultare di implementazione agevole ed economica.Nel presente lavoro si vuole evidenziare la funzionalità di uno specifico metodo di laboratorio basato sulla termografia infrarossa, applicato alla caratterizzazione del flusso d’aria in uscita da un ventilatore tangenziale ad elevato sviluppo assiale. Il fine è l’acquisizione di misure quantitative analoghe a quelle ottenibili mediante tecniche LDV o PIV applicate al medesimo problema, attuando però procedure sperimentali con complessità comparabile a quella di tecniche meno sofisticate. Obiettivo ultimo è la validazione di un modello CFD del ventilatore, realizzato tramite un codice commerciale e destinato all’integrazione in un modello complessivo di un sistema di refrigerazione con elevata efficienza.Il concetto ispiratore è che la diffusione di quantità di moto e la diffusione di energia termica hanno negli aeriformi intensità comparabile. Perciò, se il flusso d’aria prodotto dal ventilatore in esame viene immesso in un ambiente in cui è presente aria in quiete e a inferiore temperatura, si può stabilire una corrispondenza tra la distribuzione di velocità che si instaura in tale ambiente e la distribuzione di temperatura ivi presente, rilevabile mediante termografia infrarossa.
2002
- The lock-in heating-cooling method for the measurement of the thermal diffusivity of solid materials
[Articolo su rivista]
Muscio, Alberto; E., Grinzato
abstract
A new test method is presented for the on-field nondestructive measurement of the thermal diffusivity of solid materials. A periodic thermal disturbance is supplied to the inspected material by a thermoelectric source based on the Peltier effect. This can alternate heating and cooling stages and provide, it properly controlled, a harmonic disturbance with null net heat flux. A steady-periodic temperature field can thus be induced within the specimen. The diffusivity of the material is then estimated by monitoring the propagation of the temperature cycles along the optically accessible surface of the specimen, adjacent to the thermal input surface area. A camera tor infrared thermography is used for nonintrusive surface temperature measurement. At the current stage of development, the focus is on the accurate reproduction of the theoretical model on which the method is based. Ease of operation and portability of the test equipment are also par,sited. However, tests on thin specimens of materials with known properties give measurements in encouraging agreement with the nominal values.
2001
- Measurement of the thermal diffusivity of thin slab specimens by the lock-in heating-cooling method
[Relazione in Atti di Convegno]
Muscio, Alberto; F., Gavelli; Tartarini, Paolo
abstract
The present work describes a new test method for the in-situ non-destructive measurement of the thermal diffusivity of solid materials.A periodic thermal disturbance is supplied to the inspected material by a thermoelectric source based on the Peltier effect. This procedure alternates heating and cooling stages and provides, if properly controlled, a harmonic perturbation with null net heat flux. Thus, a steady-periodic temperature field can be induced within the specimen. The diffusivity of the material is estimated by monitoring the propagation of the temperature cycles along the optically-accessible surface of the specimen, adjacent to the thermal input surface area. A digital camera for infrared thermography is used to obtain non-intrusive surface temperature measurements.At the current stage of development, the focus is on an accurate reproduction of the theoretical model on which the method is based. Ease of operation and portability of the test equipment are also pursued. This notwithstanding, early tests on thin specimens of known materials have given results in encouraging agreement with the nominal values.
2001
- Numerical simulation of the cooling effect of multiple droplets on a hot solid surface
[Relazione in Atti di Convegno]
Muscio, Alberto; F., Gavelli; Tartarini, Paolo
abstract
A numerical code is presented that simulates the evaporation of water droplets on hot solid surfaces. The surface temperature conditions are such that only single-phase evaporation is obtained. The two-dimensional, axial-symmetrical energy diffusion equation, discretized with the finite volume method, is used to model the transient within both the droplets and the solid substrate.The current work simulates the substrate cooling effect due to a multi-droplet system, made of a ring of six identical droplets surrounding a central one. The overall transient is obtained by superposition of effects, from the solution for the axial-symmetrical substrate temperature field due to the evaporation of an individual droplet. The numerical results are validated by comparison with experimental data.The code is implemented in Matlab, using a modular and flexible architecture. This will allow the expansion of the code to simulate convective motion and nucleate boiling in the droplet, as well as other fluids.
2000
- Cooling of hot ceramic surfaces induced by water sprays in the nucleate boiling regime
[Relazione in Atti di Convegno]
Tartarini, Paolo; Muscio, Alberto
abstract
An experimental and theoretical research is conducted, focusing on the thermal behavior of hot, non-porous, low-conductivity surfaces during the cooling transient induced by single- and multi-droplet boiling water systems. The research is aimed at modeling the cooling effect induced on a hot solid surface by sprinkler-generated droplets. The long term objective of this study is the construction of a model for the prediction and optimization of the performance of sprinkler-based fire-extinguishment systems. In this paper, the results of a series of experimental tests on single- and multi-droplet boiling systems are presented and discussed. The main objectives of the present study are: a) to investigate experimentally the effect of the boiling onset on the cooling effect induced on the solid surface by the water droplets; b) to measure the evolution of the solid surface temperature during evaporation, with particular attention to the values of minimum, maximum and average temperature; c) to examine the possibility of improving spray cooling efficiencies.
2000
- Diffusivity measurement of thick samples by thermography and heating-cooling technique
[Relazione in Atti di Convegno]
P. G., Bison; E., Grinzato; S., Marinetti; Muscio, Alberto
abstract
The technique consisting in using a Peltier cell in contact with the material and producing successively heating and cooling conditions is presented for the measurement of diffusivity. Results on thermally thin materials with well known characteristics like stainless steel AISI 304 gives measurement values with precision around 10%. Analyzing the situation of a thermally thick marble sample, the in-depth propagation affects also the lateral ones. This is of general interest for a future use of this technique in the field where the thickness of the material may be important.
2000
- Misura della diffusività termica mediante applicazione di una sollecitazione termica ciclica alternante raffreddamento e riscaldamento
[Relazione in Atti di Convegno]
Muscio, Alberto
abstract
A new test method is presented to quantify the thermal diffusivity, devised for on-site non-destructive measurements of solids accessible from one side only.A periodic thermal disturbance is supplied to the inspected solid by a thermoelectric unit based on the Peltier effect. This can alternate heating and cooling stages and provide, if properly controlled, a null net heat flux. A steady-periodic temperature field can be quickly produced within the solid. The diffusivity of the material is then estimated by monitoring the propagation of the temperature cycles along the optically accessible surface of the solid, adjacent to the thermal input surface area. A portable camera for infrared thermography is used for non-intrusive surface temperature measurement.Tests on thermally thin specimens of materials with well known properties give measures in encouraging agreement with the nominal values.At the current stage of development, the attention is focused onto obtaining the adherence of the test system to the theoretical model on which the method is based. Ease of operation and portability of the testing equipment are also pursued.
2000
- Modeling of thermal non-destructive evaluation techniques for composite materials
[Relazione in Atti di Convegno]
S., Marinetti; Muscio, Alberto; P. G., Bison; E., Grinzato
abstract
The inspection of composite structures by thermal non-destructive evaluation (TNDE) techniques based on Infrared Thermography is relatively common in the aerospace industry. However, state-of-the-art is far to be reached and there is still place for substantial improvement, in terms of development of the inspection procedures, optimization of the experimental set-up and assessment of the inversion algorithms. This requires the availability of large amounts of reference data, which can be provided in a cost-effective way by mathematically modeling the thermal behavior of the inspected structures.The numerical simulation of procedures for thermographic inspection is investigated in this work. The analysis is focused on the strategies that can be implemented to model the heat conduction processes in composite structures typical of TNDE procedures by means of commercial software packages for coupled mechanical-thermal analyses. The results of a pilot application of a commercial software packages to a real case are finally presented.
2000
- On-site measurement of thermal diffusivity by infrared thermography and thermoelectric equipment
[Relazione in Atti di Convegno]
Muscio, Alberto; F., Gavelli; Tartarini, Paolo
abstract
The latest advancements are presented about a new method to quantify the thermal diffusivity, devised for on-site measurements of solids accessible from one side only.A periodic thermal input is supplied to the inspected solid by a thermoelectric device based on the Peltier effect, which can alternate heating and cooling stages and quickly produce a steady-periodic temperature field within the solid, with null net heat input. The diffusivity of the material is then estimated by monitoring the propagation of the temperature cycles along the accessible surface of the solid, adjacent to the thermal input area. A portable camera for infrared thermography is used for non-intrusive surface temperature measurement.Mathematical and experimental methods are utilised to identify the conditions for which a 1D heat transfer model can be used to accurately represent the actual 3D temperature field. At the present stage, the attention is focused onto obtaining the adherence of the test system to the theoretical model. Ease of operation and portability of the equipment are also pursued.
2000
- The influence of nucleate boiling regime on dropwise cooling of low-conductivity surfaces
[Relazione in Atti di Convegno]
Tartarini, Paolo; Muscio, Alberto
abstract
An experimental and theoretical research is conducted, focusing on the thermal behavior of hot, non-porous, low-conductivity surfaces during the cooling transient induced by single- and multi-droplet boiling water systems. The research is aimed at modeling the cooling effect induced on a hot solid surface by sprinkler-generated droplets. The long term objective of this study is the construction of a model for the prediction and optimization of the performance of sprinkler-based fire-extinguishment systems. in this paper, the results of a series of experimental tests on single- and multi-droplet boiling systems are presented and discussed. The effect of the boiling onset on dropwise cooling is investigated, and the possibility of improving spray cooling efficiency is examined.
2000
- Theoretical, numerical and experimental investigation of a one-side measurement technique for thermal diffusivity
[Relazione in Atti di Convegno]
Muscio, Alberto; Corticelli, Mauro Alessandro; Tartarini, Paolo
abstract
A modified Angstrom’s method for the measurement of thermal diffusivity in solid materials is presented, aimed at overcoming the limits of ordinary techniques with one-side measurements. The method requires a periodic thermal input to be supplied to the specimen, alternating heating and cooling stages. The thermal diffusivity is estimated by monitoring the temperature oscillations on the free surface of the specimen.The conditions at which a real three-dimensional test-system can be studied by means of a one-dimensional thermal model are investigated. Algorithms to estimate the thermal diffusivity are determined analytically and verified by numerical simulation. The method is finally validated by experimental measurements.
1999
- Modeling of thermal nondestructive evaluation techniques for composite materials and the European aerospace industry
[Relazione in Atti di Convegno]
Muscio, Alberto; S., Marinetti; P. G., Bison; A., Ciliberto; G., Cavaccini; E., Grinzato
abstract
Thermal non-destructive evaluation (TNDE) techniques based on IR Thermography have becoming a mature method for the aerospace industry. For the development of new procedures, the optimisation of the experimental set-up and the assessment of the inversion algorithms that are used by TNDE techniques, reference data are required, which can be provided by simulating the thermal behaviour of the inspected structures.In this work, the computerised simulation of thermographic inspection procedures by mathematical methods is investigated. The analysis is focused on the modelling strategies that can be implemented by means of commercial software packages to solve numerically the heat conduction problem in composite structures. When affordable, exact analytical solution of the heat diffusion originating during the testing procedures is reviewed as well.
1999
- Numerical investigation of a one-side measurement technique for thermal diffusivity
[Relazione in Atti di Convegno]
Barozzi, Giovanni Sebastiano; Corticelli, Mauro Alessandro; Muscio, Alberto; Tartarini, Paolo
abstract
A modified Angstrom’s method for the measurement of the thermal diffusivity of solid materials is presented, aimed at overcoming the limits of ordinary one-side techniques. The method requires a periodic thermal input, alternating heating and cooling stages, to be supplied to the specimen. The thermal diffusivity is estimated by monitoring the temperature oscillations on the free surface of the specimen.The conditions for which a real three-dimensional test-system can be studied by means of a one-dimensional thermal model are investigated by analytical and numerical methods. The algorithms for the estimate of thermal diffusivity are determined for the one-dimensional thermal system and are verified by numerical simulation. The applicability of the algorithms to multi-dimensional configurations is finally explored.
1999
- Photographic investigation of water droplet impingement and boiling on hot surfaces
[Relazione in Atti di Convegno]
Barozzi, Giovanni Sebastiano; Corticelli, Mauro Alessandro; Muscio, Alberto; Tartarini, Paolo
abstract
The present research is aimed at analyzing the behavior of small water droplets impinging, with different Weber numbers, on hot, non-porous surfaces. An experimental and theoretical study is conducted, focusing on the influence of the Weber number on the cooling effects induced by droplet impingement and evaporation in presence of nucleate boiling. In order to get more insight into the phenomenon, the droplets behavior is monitored by a high-speed video-camera, and the influence of the Weber number on dropwise evaporative cooling is analyzed. In particular, the conditions which determine the onset of nucleate boiling are emphasized, and the solid surface cooling transients are also monitored via infrared thermography.
1999
- Thermal diffusivity measurement of stainless steel by periodic heating technique
[Relazione in Atti di Convegno]
S., Marinetti; P. G., Bison; E., Grinzato; Muscio, Alberto
abstract
The use of a device based on the Peltier effect can provide heat source and sink suitable for diffusivity measurements. By performing a one-side test it is possible to estimate the diffusivity value, provided that some conditions are met. In a previous work the basic idea and the experimental set up of this method were described. A crucial point is the inversion formula that allows recovering the diffusivity value from the temperature data. The proposed analytical formula works only if the experimental parameters are suitably chosen for the particular sample under test. This paper is focused on the conditions to be met in order to correctly apply that formula. To this end, tests have been performed on a material with known thermal properties.
1999
- Thermal parameters estimation by heating and cooling and thermographic measurement
[Relazione in Atti di Convegno]
P. G., Bison; Muscio, Alberto; E., Grinzato
abstract
The use of a Peltier device in thermal contact with a specimen can provide heat source and sink. The utilization of this equipment is experimented, applying successive heating and cooling stages on various specimens and measuring the temperature outside of the contact area. Oscillating temperature in time and space can provide indication on the thermal diffusivity.The appealing ability of sourcing and sinking heat, with average null effect on temperature, may represent an innovative approach with respect to traditional stimulation technique.A simple analytical model is exploited for recovering the inversion equations. Numerical simulation allows to better understand the real process on the sample.
1999
- Thermographic investigation of water droplet boiling on hot ceramic surfaces
[Relazione in Atti di Convegno]
Corticelli, Mauro Alessandro; Muscio, Alberto; Tartarini, Paolo
abstract
An experimental research is conducted, focusing on the thermal behavior of hot, non-porous, ceramic surfaces during the cooling transient induced by single- and multi-droplet boiling water systems. The research is aimed at modeling the extinguishment of a solid fuel fire by sprinkler-generated droplets. The long term objective of this study is the construction of a model for the prediction and optimization of sprinkler-based extinguishment systems performance. In this paper, the results of a series of experimental tests on single- and multi-droplet boiling systems are presented and discussed. In order to get more insight into the solid surface temperature transients induced by dropwise evaporation and boiling, the test materials have been chosen within the category of low thermal conductivity substances (1 to 5 W m-1 °C-1), so that a relevant and well-measurable cooling effect is observed. The dropwise cooling transients are monitored by the non-intrusive method of infrared thermography, and the potentialities of this approach are stressed out.
1997
- Modellazione termica del dispositivo di scarico di motori a.c.
[Relazione in Atti di Convegno]
Muscio, Alberto; Corticelli, Mauro Alessandro; Barozzi, Giovanni Sebastiano
abstract
Si presenta un modello matematico volto alla previsione delle temperature dei gas e delle temperature di parete di dispositivi di scarico dei gas combusti prodotti da motori ad accensione comandata. Il modello, pur nell'ambito delle forti semplificazioni in esso implicite, consente la previsione del comportamento termico dei condotti di scarico con sufficiente attendibilità, come comprovato da esperienze al banco, eseguite presso il Centro Ricerche FIAT di Orbassano - TO. La tecnica predittiva proposta può consentire un più rapido sviluppo di prototipi dei nuovi sistemi di scarico, atti a meglio soddisfare i limiti di emissione sempre più stringenti proposti dalle normative internazionali.