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Dipartimento di Ingegneria "Enzo Ferrari"

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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

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 - A preliminary evaluation of different residual biomass potential for energy conversion in a micro-scale downdraft gasifier [Articolo su rivista]
Puglia, M.; Morselli, N.; Ottani, F.; Pedrazzi, S.; Tartarini, P.; Allesina, G.

2023 - Assessment of hemp hurd-derived biochar produced through different thermochemical processes and evaluation of its potential use as soil amendment [Articolo su rivista]
Puglia, Marco; Morselli, Nicolo; Lumi, Marluce; Santunione, Giulia; Pedrazzi, Simone; Allesina, Giulio

: Biochar is a carbon-rich and porous material that finds application in different sectors and can be extremely useful in agriculture as soil improver. This paper provides a comparison between biochars produced with different slow pyrolysis processes and biochar produced in a downdraft gasifier. A blend of residual lignocellulosic biomasses (hemp hurd and fir sawdust) was pelletized and used as starting feedstock for the tests. The biochars produced were analyzed and compared. Temperature proved to be the main driver in conditioning the chemical-physical characteristics of the biochars more than residence time or the configuration of the pyrolysis process. The higher the temperature, the higher the carbon and ash content and the biochar pH and the lower the hydrogen content and the char yield. The most noticeable differences between pyrolysis and gasification biochars were the pH and the surface area (considerably higher for gasification char) and the low content of hydrogen in the gasification biochar. Two germinability tests were carried out to assess the possible application of the various biochars as soil amendment. In the first germinability test, watercress seeds were placed in direct contact with the biochar, while in the second they were placed on a blend of soil (90%v/v) and biochar (10%v/v). The biochars with the best performance were those produced at higher temperatures using a purging gas and the gasification biochar (especially mixed with soil).

2023 - Biomass-powered thermal weeding in wine farms: An environmental and economic assessment [Articolo su rivista]
Morselli, N; Boccaletti, S; Meglioraldi, S; Puglia, M; Pedrazzi, S; Allesina, G

The energy transition in agriculture must be accompanied by agronomic practices that shift production towards organic regimes. Among the energy consuming processes that today find resistance in organic conversion there is certainly the removal of weeds from crops, that is mainly carried out through herbicides. This analysis evaluates the economic and environmental implications that the introduction of innovative thermal weeding systems, powered by biomass gasification, can have in the substitution of traditional chemical and mechanical weeding technologies. The comparison is carried out through a combination of cost-benefit analysis, environmental analysis and sensitivity analysis applied to the case study of vineyard management in northern Italy. The results show that the biomass-powered weeding system is economically feasible when it can benefit from economic incentives that reward organic production. In all cases, biomass-powered weeding system provides for a reduction in equivalent CO2 emissions which reaches -75% in the case of replacement of glyphosate-based chemical weeding methods. The analysis points out that gasification-powered weeding process can also achieve carbon neutrality through the co-production of biochar, which should lead policy makers to support this practice under the environmental objectives at national and European level.

2022 - An experimental approach to evaluate drying kinetics and foam formation in inks for inkjet printing of fuel-cell layers [Articolo su rivista]
Santangelo, Paolo Emilio; Romagnoli, Marcello; Puglia, Marco

Inkjet printing is a deposition technique that has remarkably evolved over the last two decades, becoming widely employed for various applications. Notably, it has proven very promising for catalyst and ionomer layer deposition in assembling CCM (Catalyst Coated Membranes) of PEMFC (Polymer Electrolyte Membrane Fuel Cells). However, fast drying of the processed inks at the outlet often causes nozzle clogging and foam formation within the supply circuit often yields poor release: these are the main challenges in applying inkjet printing on a large scale. So, an experimental approach for the evaluation of drying kinetics and foam formation in inks typically employed in fuel-cell manufacturing is presented. It allows to evaluate ink printability, compare different inks quantitatively and assess the performance of commonly used additives. Evaluation of drying kinetics is based on releasing ink droplets onto a support, then recording mass, ambient temperature and relative humidity. Foam formation is evaluated by filling a syringe with a known amount of ink, then injecting air at a set flow rate into the sampling volume: foam may be ultimately generated and its amount can be measured. Those relatively simple approaches were applied to various inks; validation was conducted by statistical analysis and by comparison with physical relationships and datasets available in the open literature.

2022 - Energy cost and parmesan cheese. An overview in the different energy fluxes needed to produce a parmesan wheel [Relazione in Atti di Convegno]
Puglia, M.; Allesina, G.; Pedrazzi, S.; Raguzzoni, F.

Agriculture is responsible for up to 30% of the greenhouse gases emission, and cattle breeding is the main contributor making up almost 10% of the total. For this reason, this sector is a key player toward a complete decarbonization. To take the proper action to reduce climate impact of cattle breeding, it is necessary to know the energy requirements of the industry. This work focuses on the energy mapping of a parmesan cheese production, with reference to an agricultural company situated in Modena province with about six hundred animals. Knowing the electrical and thermal energy requirements to produce a wheel of cheese gives the possibility to the farmers to identify and reduce the energy wastage as well as starting the implementation of a strategy for fossil fuel substitution. In this study, a comprehensive monitoring campaign is presented together with the proposal of some possible improvements. The analysis showed that, considering the actual situation, about 64 kWh of electrical energy and 94 kWh of thermal energy are needed to produce a parmesan cheese wheel, while the fuel used to feed the agricultural machinery (e.g., tractors) accounts for around 174 kWh. In this context, the implementation of biogas and solar photovoltaic can greatly contribute to reduce the dependence on fossil fuels.

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.

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 - Experimental analysis of effective energy dosage in hot air weeding [Articolo su rivista]
Morselli, N.; Ottani, F.; Puglia, M.; Pedrazzi, S.; Tartarini, P.; Allesina, G.

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.

2022 - Pyrolysis Process for the Recycling of Cork Dust Waste from the Processing of Cork Agglomerate Caps in Lightweight Materials [Articolo su rivista]
Coppelli, Paride; Pedrazzi, Simone; Puglia, Marco; Morselli, Nicolo'; Allesina, Giulio; Andreola, Nora Maria; Lancellotti, Isabella; Barbieri, Luisa

This study aimed to investigate the possibility of recycling cork scraps derived from the production of agglomerated bottle caps containing organic additives (glues and adhesives) in addition to virgin wood. The study involved pyrolysis treatment followed by the use of char to obtain lightweight material prototypes. The scrap was pyrolysed in order to achieve the thermal degradation of unwanted molecules with decomposition temperatures lower than the pyrolysis temperatures, but also to achieve the reduction in mass and size of the starting material. The substitution of 15% by weight of weight-lightening agent (char from pyrolysed cork, or half char and half spent coffee grounds) into the clayey matrix made it possible to obtain lightweight aggregates with pH and conductivity values that could be exploited in an agronomic context. The substitution of clay with of 5 to 15% by weight of pyrolysed cork char in the production of specimens pressed at 25 bar and fired slowly at 1000 ◦C led to lightweight ceramics with particularly interesting porosity (from 41 to 68%) and bulk density (850–1600 kg/m3) values.

2021 - A low impact alternative to common weed control systems: the case of syngas-powered flame weeding [Relazione in Atti di Convegno]
Morselli, N.; Puglia, M.; Balboni, C.; Ottani, F.; Parenti, M.; Santunione, G.; Pedrazzi, S.; Allesina, G.; Tartarini, P.

In this work, a simple model was created to estimate the benefits of replacing the LPG, currently used in flame weeding, with the syngas generated from a biomass gasification system. Results shown that 60.1 kg ha-1 of agripellet are enough to substitute 16.4 kg ha-1 of LPG when a gasification efficiency of 70% is considered. The model shown a CO2 generation of 49.8 kg ha-1 for each treatment using the LPG device and 94.5 kg ha-1 for the biomasspowered weeder which is, however, a biogenic source of carbon with a neutral impact on the climate. Moreover, for the gasification facility, a 3.3 kg ha-1 co-production of char was considered which led to the possible stock of 9.6 kgCO2 ha-1 each treatment. Eventually, the proposed model suggests that a net saving of 58.5 kgCO2 ha-1 can be realized if LPG flame weeding treatment is replaced with a syngas-powered flame weeder.

2021 - A preliminary study on torrefaction pretreatment of hemp stem for waste-toenergy valorization of woody biomass from flower hemp cultivation [Relazione in Atti di Convegno]
Parenti, M.; Ottani, F.; Puglia, M.; Morselli, N.; Pedrazzi, S.; Allesina, G.

Hemp cultivation gained an important role in recent years. Two major production chains can be defined, one dedicated to the cultivation of hemp for the production of fiber and wood and the other relating to the production of inflorescences for the market of derivative products containing cannabidiol, better known as CBD. The problem that will be highlighted and addressed in this article is related to the enhancement of cannabis production waste for CBD. In particular, since flowers are the only useful part of crops dedicated to this purpose, to date the stems of plants are considered a difficult waste to exploit. The alternatives are few and one of the simplest and most immediate is certainly the waste-to-energy process of this material; in fact it is not possible to obtain fiber and wood of good quality from the CBD production chain, because these crops are optimized for flower production. Waste-to-energy, on the other hand, requires mechanical pre-treatments in order to use the raw material within the typical thermal conversion systems (e.g. biomass boilers, pellet stoves, gasifiers). The great obstacle to being able to efficiently transform these wastes into fuel, lies in the very nature of the hemp stems as the fibers constituting the outermost part of the plant stems are well known for their good mechanical resistance. These properties however become a problem when the material has to be treated with standard machinery for pelleting and briquetting, as they hind the mechanical components suitable for the purpose giving rise to maintenance and breakdown issues. To solve the problem, the possibility of decreasing the mechanical properties of hemp fibers has to be investigated, so as to permit the transformation of this material into an economically sustainable fuel. It was therefore decided to pre-treat the stems of the plants with a torrefaction process, to sufficiently weaken the fibers to be mechanically treated. Shear resistance was tested with a “piston device” to obtain a qualitative estimate of the mechanical behaviour of the hemp fibers only; in fact it is assumed that to solve the problem, it is sufficient to concentrate on the weakening of the fiber instead of the entire stem of the plant. In conclusion, a first estimate is defined of the minimum energy necessary for the roasting of the plant stems, sufficient to weaken the fibers to make the mechanical transformation of the stems of hemp plants into fuel, possible and economically sustainable.

2021 - Domestic heating: Can hemp-hurd derived pellet be an alternative? [Articolo su rivista]
Morselli, N.; Puglia, M.; Pedrazzi, S.; Tartarini, P.; Allesina, G.

Among the renewable sources, residual woody biomass from agricultural crops is becoming of great interest due to its lower environmental impact and one of the most growing agricultural sector, of the last decade, is the hemp industry which generates several kind of byproducts. In this paper, a blend of 50% of hemp-hurd and 50% of fir sawdust was pulverized and pelletized. The pellets were burned into a domestic pellet stove (9 kWth maximum nominal thermal power output) at different biomass flowrates. To compare results with a commercial-grade pellet, the tests were repeated by fueling the same stove with A2-grade pellets. Results shown that the pellet mixture 50/50 of fir sawdust and hemp-hurd is suitable for the commercial pellet stove used and that the slightly higher amount of ashes (2.7%), compared to pellet A2 (<1.2%), can be handled by the self-cleaning fire chamber. Comparable results were also obtained in regards with the stove global efficiency which ranged from 90.8-92.3% for the hemp pellets and 91-94% for the A2. A significant difference was noted in the biomass flowrate where, during the tests with hemp-hurd pellets a lower value was obtained (-20%) compared to A2. This resulted into lower power input in the stove and lower performances at the same nominal power output.

2021 - Emission analysis of syngas combustion and flammability limit assessment [Relazione in Atti di Convegno]
Puglia, M.; Parenti, M.; Tartarini, P.; Ottani, F.; Allesina, G.; Pedrazzi, S.; Tioli, J.

Gasification of biomass can be a very effective technology to fight climate change due to the carbon negativity of the process. However, syngas combustion could release a variety of pollutant compounds such as carbon monoxide and nitrogen dioxide. Improving the emissions of syngas combustion is very important in order to promote the diffusion of small scale gasifiers that often have no complex flue gas treatment systems. In this work a study on syngas combustion from a small scale gasification system is presented. A combustion chamber designed after a preliminary numerical evaluation was built to test different geometrical configurations. Two metal plates were used to modify the combustion chamber geometry in order to test different flare shapes. An experimental campaign with an emission analyzer was carried out to identify the best combustion chamber shape and to evaluate the pollutant released by syngas combustion. To further explore syngas combustion, the flammability limits were evaluated through the “Le Chatelier” equation and considering the presence of various inert gases.

2021 - Experimental heat transfer evaluation in a porous media [Relazione in Atti di Convegno]
Pedrazzi, S.; Allesina, G.; Puglia, M.; Morselli, N.; Ottani, F.; Parenti, M.; Tartarini, P.

The evaluation of the heat transfer coefficient between hot gases and biomass particles is not easy to estimate because of the concomitance of exothermic and endothermic reactions. However, a proper evaluation of this coefficient is fundamental to design pyrolysis apparatus. This paper presents an experimental study regarding wood pellets heating up in a batch reactor using hot exhaust gases from an engine. Temperature and flow of hot gases entering the reactor were measured over time. A first test was carried out using hemp hurd pellets with 15% of sawdust, and a second one using the carbonized pellets obtained from the previous test. Fresh pellets have a higher thermal capacity compared to carbonized pellets that is almost inert and follow a more regular heating trend. Heat transfer was calculated considering the energy released by the exhaust passing through the biomass as the sum of the energy absorbed by the pellets and the thermal losses. Convection is the predominant heat transfer mechanism and the convective heat transfer coefficient was evaluated. Finally, the energy for the pyrolysis of 1 kg of fuel was evaluated. About 0.7 kWh/kg are necessary to pyrolyze this kind of pellets while an heat transfer coefficient of 110 W/(m2K) was estimated for the inert packed bed.

2021 - Numerical and experimental evaluation of flue gas recirculation for syngas combustion [Relazione in Atti di Convegno]
Allesina, G.; Puglia, M.; Morselli, N.; Pedrazzi, S.; Parenti, M.; Ottani, F.; Tartarini, P.

Biomass gasification can be an interesting solution for the energy production to fight global warming and the environment pollution. The flare apparatus is an essential component of gasification systems, but considering small scale ones, it is often quite simple and not very optimized. A way to minimize the NOx production during the combustion is recirculating the flue gas into the flames, making the combustion zone cold and inhibiting the nitrogen oxides formation. In this work different flare designs were numerically evaluated through OpenFOAM software to find the best flare shape that can guarantee the flue gas recirculation. Simulations results were verified building and testing a flare with an optimized geometry for a small-scale gasification system. Numerical simulation and experimental tests shown that it can be possible to design a simple flare for syngas combustion that guarantee low combustion temperature through flue gas recirculation.

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.

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.

2020 - An explicit finite-differences heat conduction model for slow pyrolysis time calculation [Relazione in Atti di Convegno]
Ruy, A. F.; Puglia, M.; Morselli, N.; Pedrazzi, S.; Allesina, G.

slow pyrolysis is one of the most common pyrolysis variations, traditionally used to obtain high yields of charcoal or syngas. Although this is a widely known and used method and its complex heat transfer and kinetics mechanisms are already deeply studied, there is no simple and direct method to calculate the time needed to pyrolize different kinds of biomass. This work aims at structuring a solid algorithm capable of predicting pyrolysis time inside a real scale tubular reactor through an explicit finite-differences heat conduction model. Bulk properties and simplifying assumptions are made to make possible to consider the whole biomass volume as a single solid with spatial temperature dependent properties calculated at every iteration. Numerical results are within expected and further works needed to validate the model are undergoing development.

2020 - Equilibrium modeling of hemp hurd gasification [Relazione in Atti di Convegno]
Pedrazzi, S.; Morselli, N.; Puglia, M.; Ottani, F.; Parenti, M.

The aim of this work is modeling a gasification process where a non-conventional biomass is used as fuel: Hemp hurd residues. An equilibrium model of the gasification reaction was implemented in the PhytonTM software environment. Syngas composition, syngas higher heating value, tar production and gasification cold gas efficiency were evaluated at different value of biomass moisture starting from biomass ultimate analysis and reaction equivalence ratio (ER) value. The model is able to predict char and tar production as function of biomass composition, moisture and ER. A comparison with experimental data obtained from hemp hurd gasification was done to validate equilibrium model results. Gasification tests were performed using a low capacity lab-scale gasification reactor designed to use about 1 kg per hour of dry biomass fuel. Results show small errors between model results and experimental result. Several simulations were performed to assess the gasification dependency on selected boundary conditions like biomass moisture and ER of the gasifier.

2020 - Experimental and modelling evaluation of possible solutions for compact design of producer-gas heat exchangers [Relazione in Atti di Convegno]
Morselli, N.; Puglia, M.; Mason, J.; Parenti, M.; Ottani, F.; Tartarini, P.

An experimental and numerical campaign was carried out to investigate the performances of tubes in shell heat exchanger applied to cool down the producer gas of a small-scale commercial wood biomass gasifier built by All Power Labs. Producer gas is contaminated with soot and tars that condensate under 300 °C, for this reason the heat exchanger was designed in order to have an in-situ cleaning mechanism. The heat exchanger was tested both with standard plain tubes and with a set of metal twisted tapes (TT) with the aim of enhancing the heat transfer between producer gas and water. Temperatures and mass flows analyses shown a maximum increase of thermal power output and overall heat transfer coefficient respectively of 19% and 76% when TT are applied to the standard plain tubes in shell heat exchanger. Numerical simulations shown a consistency in the trends giving an average discrepancy with experimental results of the 12%.

2020 - Gas Consumption and Growth Performance of N. oleoabundans in the 30 L Photobioscrubber. [Abstract in Atti di Convegno]
Altunoz, M.; Puglia, M.; Morselli, N.; Tioli, J.; Allesina, G.; Pedrazzi, S.; Arru, L.

2020 - Hemp by-product valorization [Relazione in Atti di Convegno]
Pedrazzi, S.; Morselli, N.; Puglia, M.; Santunione, G.; Parenti, M.; Ottani, F.

This paper investigates possible circular economy pathways which can be applied in different hemp agriculture regimes using hemp by-products. Not only open field hemp cultivation but also the case of hemp growing in indoor greenhouses is presented. Several valorization technologies has been applied to achieve economic and environmental advantages for the farmer: Composting of green and wet residues, combustion and gasification of hemp stalks and hurds, co-composting of hemp green residues (leafs and branches) and biochar obtained from hemp ligneous residues (stalk and hurd). Every pathways is discussed from the practical point of view and also considering the entire framework including all the stakeholder involved in the process.

2020 - Implementation of a portable petrol - powered generator fueled through a tabletop biomass gasifier [Relazione in Atti di Convegno]
Puglia, M.; Morsell, N.; Ottani, F.; Tartarini, P.

Portable petrol powered generator are very popular around the world. They are used mostly when electrical power from the grid is not available, for example in blackout scenarios, remote areas or for temporary use and they are basically irreplaceable in many cases. The idea behind this work is to substitute the fossil fuel as the energy source of these systems with the syngas produced through biomass gasification, that is a carbon negative energy process in order to achieve a complete decarbonisation as soon as possible. Coupling gasifiers and reciprocating internal combustion engine is a very old technology, however there are no small and cheap systems available that can be successfully connected to this kind of generator. The laboratory scale gasifier presented in Lisbon at the 27th EUBCE in the paper titled: “Design and first tests of a micro lab scale (2kg/h) gasifier” after a series of test has been improved enhancing its efficiency, gas quality and power output. A GeoTech GGP 4000 ES petrol powered has been selected to operate with the syngas from the gasification system and its intake manifold has been modified. The gasifier is able to operate with different kinds of biomasses like wood fir pellets, wood chips, vine prunings pellets, hemp hurd etc. The fuel chosen for the test was the standard A1 ENPlus wood pellet. An Iveco air filter was used to preserve the engine from the tars and particulate present in the gas. The energetic consumption was calculated and the thermal power output from the engine exhaust was estimated measuring gas composition and the air flow and entering in the gasifier. The results from the test show that it is possible renew the way the portable petrol generator are used, making them efficient and eco-friendly without increasing dramatically the complexity of the system or the costs.

2020 - Temperature and residence time influence on the cattle manure separated solid phase carbonization [Relazione in Atti di Convegno]
Puglia, M.; Marchesini, V.; Tassoni, G.; Tioli, J.; Tartarini, P.

This work aim to investigate the effect of temperature and residence time on the carbonization of the cattle manure separated solid phase. The same lab scale auger pyrolizer presented at the 26th European Biomass Conference and Exhibition in the work “Carbonization of residual biomass from river maintenance using waste heat from gasification power plants” was used to carbonize the separated solid obtained from the “SEPCOM Cow Bedding” cattle manure separator. This material is a high quality organic soil conditioner, easy to shovel, store and transport, it is odorless and it can be use as bedding or as soil conditioner. First of all, the material was analyzed measuring its ash percentage, its moisture and its elemental composition, and performing thermal gravimetric and differential thermal analyses on it. 11 pyrolysis tests were carried out with three different temperatures, 300 °C, 400 C° and 500 °C, and 5 residence times, 11, 22, 30, 60 and 90 minutes. As thermal source the exhaust gas from a portable petrol powered generator was used sending it into the jacket around the auger. The residence time was controlled through an Arduino Board that managed the auger movement. The residues of the 11 carbonization tests were analyzed again to measure their ash quantitative and elemental composition. The results showed that with the pyrolysis temperatures at 500 °C it was possible to achieve a percentage of carbon over the 70% and reduce the dry matter of the material by two – third, moreover longer residence times bring to higher weight losses, compared to the shorter ones, mostly for low pyrolysis temperatures.

2020 - Vine prunings agro – energetic chain: Experimental and economical assessment of vine pellets use in gasification power plants [Relazione in Atti di Convegno]
Puglia, M.; Torri, G.; Martinelli, V.; Tartarini, P.

Vine prunings are a very abundant by product of the wine industry and their production can be estimated to be between 1 to 5 ton/year for every hectare. In the view of a decarbonisation and the development of the circular economy this biomass should become an opportunity even if in most of the cases it ends up being a problem. This is due to their common burning in situ that has a huge environmental impact, and to their shredding when left on the field that can be an infection source in presence of grape diseases. This work follows the one presented the 26th EUBCE “Gasification and wine industry: Report on the use vine pruning as fuel in small – scale gasifiers” where it was evaluated the possibility of producing electrical energy using this biomass as fuel in APL PP20 gasifier – engine system. The results of the previous work showed quite promising results about the gasification efficiency and the quality of the gas produced using this biomass, however the difficulties encountered during the reactor feeding and the bridging problems have made this process quite challenging. In order to overcome these issues, it was considered the possibility of pelletizing this biomass. More than 2.5 ton of pelletizing vine prunings were successfully gasified with a quite high efficiency, 1.1 kg consumed for every electric kWh produced. The 150 kg of biochar produced through the process were tested on a vineyard as soil improver. The entire supply chain, from the harvesting of the vine prunings on the field, to the pelletization and gasification, was economically evaluated considering different possible scenarios and some of them were quite profitable and therefore practically feasible.

2019 - Compression ratios comparison between engines operating with producer gas [Relazione in Atti di Convegno]
Mason, J.; Kaufmann, B.; Tartarini, P.; Puglia, M.; Morselli, N.; Veratti, G.; Bigi, A.

2019 - Design and first tests of a micro lab scale (2kg/h) gasifier [Relazione in Atti di Convegno]
Puglia, M.; Morselli, N.; Tartarini, P.

Most of the gasification systems cost various tens or hundreds of thousands of euros, take up a lot of space and need trained staff to be operated. This implies that biomass gasification tests are usually expensive and complex to carry out. From all these difficulties arise the need of a solution that is simple, cheap and small, allowing experimental studies without all the issues related to a commercial power plant. A laboratory scale gasifier was designed and built to meet this need. The main features of the system are the use of stainless steel for all the parts, the small size that allows to use it on a worktable and the nominal biomass flow rate of 2 kg/h. Data from literature was used to size the gasifier and choose its main parameters after an interpolation process. The interpolation was necessary because most of the data available refers to systems at least one order of magnitude more powerful than this prototype. Fir wood pellet was tested as a benchmark of the gasification system. Thanks to the manageability of the system it will allow to test different kinds of biomass. Gas-chromatographic analyses and tar and particulate sampling were carried out in order to evaluate the gas produced by the system. Elemental analysis of the char extracted from the lower part of the gasifier was performed to assess its quality. First results showed that the composition and the amount of contaminant of the gas are similar to the ones produced in much bigger power plant and also the char composition is the typical one for pyrogasification.

2019 - Efficiency and economical assessment of a solar powered dryer combined with a biomass gasification system [Articolo su rivista]
Puglia, M.; Rizzo, A.; Morselli, N.; Tartarini, P.

This work follows the study presented in Matera at the 4th AIGE/IIETA International Conference titled: “Analysis of energy saving potential of combined thermal solar power and micro scale gasification systems”. This previous work was focused on the advantages gained through the integration between thermal solar power and a small scale gasification system and how to maximize them. The results showed that the best way to combine the two systems is to use to heat generated with the thermal solar power to dry the fuel rather than heat up the gasification air. In this second work the best scenario will be analyzed considering the annual irradiance in the Province of Modena in northern Italy. The systems considered in this study were the APL PP30, a biomass gasifier genset system able to produce 22 kWel at 50 Hz, and the Chromasun Micro-Concentrator (MCT), a high performance solar collector able of 2.2 kWt output peak at DNI of 1000 W m-2. Results showed that four thermal solar units are sufficient to dry the biomass consumed in a year by the gasifier, increasing substantially its efficiency. The economic feasibility of this scenario was investigated considering a possible substitution of the methane as the heat source of the biomass dryer. Considering a discount rate of 5 % and an inflation rate of 2.5 % it is possible to have a positive NPV after 22 years from the purchase of the 4 thermal solar units. Furthermore, it is possible to save 2286 kg of CO2 using solar energy rather than methane every year.

2019 - Passive system for internal surface cleaning and homogenization in the air-lift vertical column photobioreactors [Relazione in Atti di Convegno]
Morselli, N.; Altunoz, M.; Puglia, M.; Arru, L.; Tartarini, P.

the mixing and surface cleaning performances of an air-water diffuser is tested in a 70 L air-lift bubble column photobioreactor in which single-celled Cyanobacteria Synechocystis sp. fed by sewage sludge waste is cultivated. Results have shown that a water velocity of 0.2 ms-1 in the non-aerated bottom part of the PBR and 0.06 ms-1 in the aerated zone are sufficient to prevent sludge deposition and biofouling on the surfaces. Moreover, water recirculation is observed to have an important role on the sludge mixing and algal homogenization of the photobioreactor. A computational model is then created and tuned using experimental data in order to predict the water and air velocity map in the whole domain.

2019 - Results of the two-year rebaf project: How to exploit biomass from river maintenance [Relazione in Atti di Convegno]
Pedrazzi, S.; Morselli, N.; Puglia, M.; Barbieri, L.; Lancellotti, I.; Andreola, F.; Malcevschi, A.; Giorgini, L.; Ceotto, E.; Tartarini, P.

This paper discusses activities and results of the REBAF project: a two-year Italian regional research project focused on the energy conversion of biomass residues from river, canals and basins maintenance activities. Innovative pathways for the exploitation of grass and woodsy biomasses were investigated. Gasification and pyrolysis are the key technologies for biomass conversion into energy. Woodsy biomass was tested as fuel in a small scale commercial gasification power plants that produce heat and power using a IC engine. A valuable by-product of the process was biochar. This was tested as soil improver in giant reed crop parcels and a sensible increase of dry biomass production was achieved in comparison with control parcels. The grass residues obtained from canals maintenance were carbonized in lab-scale pyrolyzer at a temperature of about 450 °C through the hot exhaust of the engine fueled by the gasifier. The pyrolysis gases were used directly in the gasifier in substitution of the gasifying agent. The residual carbon afterward the pyrolysis process was used as filler in cements, plasters and polyurethane panels increasing performance of these building materials.

2019 - Study of copper content distribution through the thermochemical conversion chain of vine pruning biomass [Relazione in Atti di Convegno]
Santunione, Giulia; Bigi, Alessandro; Puglia, Marco; Morselli, Nicolò; Sebastianelli, Lorenzo; Tartarini, Paolo

Viticulture is mostly affected by a continuous use of copper-based fungicides to contrast fungal diseases. This treatment, used in both traditional and organic cultures, results in a considerable accumulation of Cu in the top soil, then into plants and soil biota. Furthermore, Copper tends to migrate into air, water and soil ecosystem, posing serious threats to the environment and human health because of its toxicity. At the same time, vineyard pruning represent a valiant woody biomass source for renewable energy production through gasification, the thermochemical process where carbonaceous material is converted into a gaseous flammable fuel called syngas. Currently, one of the important challenges for bioenergy production through gasification is the management of heavy metal-contaminated biomasses used as fuel. This study is aimed to investigate the distribution of copper through thermochemical conversion chain of wood grape, from biomass to electrical and thermal energy production. Starting to the amount of Cu based fertilizers applied to traditional and organic viticulture, the heavy metal residues have been checked and analyzed into ashes biomass derived, into gas emissions coming out from PP20 gasifier and into biochar as gasification process by-product. Inductively coupled plasma mass spectrometry (ICP-MS), and X-ray Fluorescence spectroscopy (XRF) methods have been performed in order to quantify the amount of residual Copper into the different tested arrays. The assessment of Cu persistence along the thermochemical treatment chain of grape biomass is provided. © 2019 ETA-Florence Renewable Energies.

2019 - Use of fabric filters for syngas dry filtration in small-scale gasification power systems [Relazione in Atti di Convegno]
Morselli, N.; Parenti, M.; Puglia, M.; Tartarini, P.

This work focused on the assessment of the wood gas filtrating performances of fabric filter bags applied to a small-scale commercial gasification power plant by All Power Labs. As known, the raw producer gas contains pollutants such as tars and particulate matter that need to be removed in order to avoid the premature failure of the mechanical parts of the facility and of the internal combustion engine. PTFE-coated and felt bags were tested to assess their response to the tars and water vapors condensation, in terms of pressure drop. The results shown on one hand the tendency of felt bags to be more sensible to condensation phenomena and on the other hand the drawback of PTFE bags to generate higher pressure drop since the beginning. The possibility of pre-coating the felt bags with fine biochar generated from the gasification facility was then tested. Tars and soot gravimetric analyses conducted on wood gas samples shown the ineffectiveness of pre-coating using char and the coherent tendency of felt bags to increase the filtration performances over time.

2018 - Carbonization of residual biomass from river maintenance using waste heat from gasification power plants [Relazione in Atti di Convegno]
Puglia, Marco; Pedrazzi, Simone; Allesina, Giulio; Morselli, Nicolò; Tartarini, Paolo

This work follows the study presented in Stockholm at the 2017th EUBCE titled: “The Energetic Recover of Biomass from River Maintenance: the REBAF Project”. This previous work focused on the multidisciplinary approach to river maintenance in order to create more resilient systems together with the production of renewable energy. One of the outputs of the preliminary work presented was the distinction of the biomass from river maintenance into two major groups: suitable for gasification and not suitable for gasification. It was necessary to determine suitable and sustainable solutions for the energy recovery of both these groups. The final idea is discussed in this work, it consists in having an integrated system as depicted in Figure 2. The gasifier-engine system is fed with the higher quality biomass; it provides electrical power and hot exhaust gases that are used for the pyrolysis of the low-quality feedstock. The purpose of the pyrolysis reactor is to produce biochar to be used together with clay and other aggregates to produce highly porous, carbon negative, building materials. In this work a prototype reactor was assembled and tested using herbaceous biomass. Several configurations, in terms of exhaust gas temperature and biomass residence time were tested. Results showed the capability of coupling gasification and pyrolysis into integrated systems to increase the overall sustainability of the processes. On the other hand, char quality is strongly affected by the way this interaction is performed due to the quick cool down of the exhaust gases when the connection lines are not properly insulated.

2018 - Chemically enhanced char for syngas filtering purposes [Relazione in Atti di Convegno]
Pedrazzi, S.; Allesina, G.; Sebastianelli, L.; Puglia, M.; Morselli, N.; Tartarini, P.

This paper investigates the performance of gasification char as syngas filter medium. Char obtained from a small-scale downdraft gasifier was analyzed and chemically enhanced through an acid treatment using a sulfuric acid solution in a thermostatic bath at 40 °C. The treated char presents a higher BET value of 465.9557 m2/g in comparison with the untreated sample which has a BET value of 394.4430 m2/g. However, the treated sample has a low metallic cations content (K, Fe and Sr) and consequentially a low ash content compared to the untreated sampled. Char samples are used as cartridge filter media in order to assess their tar adsorption potential using a modified “Tar Sampling Protocol” method. Experimental results show a noticeable tar content reduction in the syngas using char as filter, in fact the treated char reduces the tar number from 1456 mg/Nm3 to 267.2 mg/Nm3 and the untreated char reduces the tar number from 1456 mg/Nm3 to 179.6 mg/Nm3. The difference in the tar adsorption is probably given by the char ash content that it is less in the treated sample.

2018 - Energy production and carbon sequestration in wet areas of Emilia Romagna region, the role of Arundo Donax [Articolo su rivista]
Allesina, Giulio; Pedrazzi, Simone; Ginaldi, Fabrizio; Cappelli, Giovanni A.; Puglia, Marco; Morselli, Nicolò; Tartarini, Paolo

This work investigated the utilization of giant reed as energy crop applied marginal areas of the municipality cluster "Unione Terre d'Argine" (UTA), Northern Italy. On one hand, the researchers modeled the giant reed productivity in terms of ton/year for each town of the cluster. They focused on those areas neighboring the local rivers and channels kept unused for farming activities: i.e. riverbanks or detention basin shores. On the other hand, experimental tests were performed to determine the behavior of giant reed as fuel in pilotscale gasification power plants. Results showed the high potential of small or pilot-scale gasifiers to increase the sustainability of river maintenance operations. From its gasification it is possible to produce electrical power together with biochar. Biochar is a powerful soil amendment that can be used straight in the riverbanks. The tandem process between giant reed growth and its gasification leads to 150 kg of CO2 sequestered for every ton of giant reed processed. Furthermore, the energy production from waste biomasses will help to perform better and more regular maintenance operation to the local rivers and channels, thus reducing the negative effects of possible floods.

2018 - Gasification and wine industry: Report on the use vine pruning as fuel in small -scale gasifiers [Relazione in Atti di Convegno]
Allesina, Giulio; Pedrazzi, Simone; Puglia, Marco; Morselli, Nicolò; Allegretti, Francesco; Tartarini, Paolo

Ten different types of vine prunings were tested in a small-scale commercial gasifier produced by the All Power Labs. The specific consumption of the wood biomass power plant was measured for each type of biomass showing results from 0.92 to 1.32 kg/kWh. Syngas analyses and HHV calculation showed results higher than the reference calculated value from the gasification of typical wood biomass. On the other hand, the feeding operations resulted more complicated, here vine prunings are more likely to create bridging problems.

2018 - Gasification of cotton crop residues for combined power and biochar production in Mozambique [Articolo su rivista]
Allesina, Giulio; Pedrazzi, Simone; Allegretti, Francesco; Morselli, Nicolò; Puglia, Marco; Santunione, Giulia; Tartarini, Paolo

Cotton agricultural industry is an important sector for some developing countries, whose energy consumption is dramatically rising. Here, biomass is the most important source of energy, but they are used in an inefficient way, causing atmospheric pollution and wasting resources. Combined energy generation and biochar production using cotton residues briquettes as fuel in a PP20 gasifier plant is investigated. The machine has demonstrated similar performances to its “conventional” use: 14% global efficiency and 1.16 kg/kWhelspecific consumption of cotton briquettes are observed. It is calculated that one-hectare field can generate more than 4 MWh and about 130 kg of biochar per year. Biochar represents a valuable by-product; if used as amendment for cotton growth it can improve the soil conditions, both decreasing the need of fertilizers up to 50%. A circular economic model based on cotton waste gasification is proposed. Clean and affordable energy can be produced, in order to promote a sustainable development of rural areas.

2018 - Use of gasification char for hot gas filtration in micro-scale power plants [Relazione in Atti di Convegno]
Morselli, Nicolò; Allesina, Giulio; Pedrazzi, Simone; Puglia, Marco; Mason, James; Lemberger, Adrienne; Tartarini, Paolo

Char is a carbonaceous gasification by-product often used as soil amendment due to its high porosity and recalcitrant structure. Porosity is a fundamental feature when char is used to adsorb liquids and aerosol. This paper investigates gasification char as filtering medium for producer gas in small-scale gasifiers. Two metallic candle filters filled with about 1 kg of gasification char each were fabricated and tested under different temperature conditions (60, 70 to 80 °C). Char behavior as tar and particulate filter is qualitative and quantitative assessed evaluating tar deposits afterwards the engine governor as well as using the “Tar Sampling Procedure” methodology. Encouraging performance of char candle filters was achieved with a producer gas temperature of 60 °C and with gas-air mixture temperature of 70 °C at the engine manifold. Furthermore pressure drop across the filters was monitored and its influence on the engine maximum power output was evaluated.

2017 - Experimental investigation on a Common Rail Diesel engine partially fuelled by syngas [Articolo su rivista]
Rinaldini, Carlo Alberto; Allesina, Giulio; Pedrazzi, Simone; Mattarelli, Enrico; Savioli, Tommaso; Morselli, Nicolo'; Puglia, Marco; Tartarini, Paolo

The high efficiency, reliability and flexibility of modern passenger car Diesel engines makes these power units quite attractive for steady power plants totally or partially running on fuels derived from biomass, in particular on syngas. The engine cost, which is obviously higher than that of current industrial engines, may not be a big obstacle, provided that the re-engineering work is limited and that performance and efficiency are enhanced. The goal of this work is to explore the potential of a current automotive turbocharged Diesel engine running on both Diesel fuel and syngas, by means of a comprehensive experimental investigation focused on the combustion process. The engine is operated at the most typical speed employed in steady power plants (3000 rpm), considering three different loads (50–100–300 Nm/16–31–94 kW). For each operating condition, the syngas rate is progressively increased until it provides a maximum heating power of 85 kW, while contemporarily reducing the amount of injected Diesel oil. Maximum care is applied to guarantee a constant quality of the syngas flow throughout the tests, as well as to maintain the same engine control parameters, in particular the boost pressure. It is found that in-cylinder pressure traces do not change very much, even when drastically reducing the amount of Diesel fuel: this is a very encouraging result, because it demonstrates that there is no need to radically modify the standard stock engine design. Another promising outcome is the slight but consistent enhancement of the engine brake efficiency: the use of syngas not only reduces the consumption of Diesel oil, but it also improves the combustion quality. The authors acknowledge that this study is only a starting basis: further investigation is required to cover all the aspects related to the industrial application of this syngas-Diesel combustion concept, in particular the impact on pollutant emission and on engine durability.

2017 - Multi-phase fluid dynamic of syngas flow across a throttle body in a gasifier-engine system [Relazione in Atti di Convegno]
Allesina, Giulio; Pedrazzi, Simone; Puglia, Marco; Morselli, Nicolò; Mason, Jim; Tartarini, Paolo

Electronically controlled throttle valves are often used in syngas fueled engines in order to maintain the engine speed constant under variable load and gas composition conditions. The producer gas carries two macrocategories of pollutants: tars (naphthalene, benzene, toluene etc. in vapor phase) and particulate matter; a high concentration of these species leads, almost certainly, to governor stuck or failure. These malfunctions force to engine shutdown. Since it is not always possible to move towards to a better syngas filtration, especially on small scale systems, it is fundamental to investigate the way of fouling of this device. This preliminary study lead to the conclusion that a combined CFD and psychrometric approach is required for a better comprehension of the fouling phenomena.

2017 - Preliminary Analyses on an Algae-Based Water Scrubber for Syngas Cleaning [Articolo su rivista]
Allesina, G; Pedrazzi, S; Altunoz, M; Morselli, N; Puglia, M; Allegretti, F; Leonardi, C; Giorgini, L; Arru, L; Tartarini, P

Common issues of the gasification systems relate to filtering apparatus. Dry filtering processes are simple and reliable. However, the filtering material defines the maximum and minimum temperature at which the filter can operate properly. In addition, dry filtration is not effective on light tar compounds (i.e. benzene and toluene) or ammonia compounds. On the other hand, despite being very efficient, wet filters drop the gas temperature below the line of condensation of tar, ammonia and steam. The resulting condensate is normally disposed at a high cost on account of the high amount of hydrocarbons it contains. This work investigates the effects of a specific micro-algae growth on the waste-water from a syngas water scrubber. The results demonstrated the capability of the algal growth in the tar-contaminated water in which a certain amount of contaminants have been dissolved. Quantitative analyses of the compounds outlined the effect of algal growth on the reduction of several chemical species derived from the syngas filtration.

2017 - The energetic recover of biomass from river maintenance: The rebaf project [Relazione in Atti di Convegno]
Pedrazzi, Simone; Allesina, Giulio; Morselli, Nicolò; Puglia, Marco; Barbieri, Luisa; Lancellotti, Isabella; Ceotto, Enrico; Cappelli, Giovanni Alessandro; Ginaldi, Fabrizio; Giorgini, Loris; Malcevschi, Alessio; Pederzini, Chiara; Tartarini, Paolo

This paper exposes the first year of activities regarding an Italian regional project called REBAF (RecuperoEnergeticoBiomasse Alvei Fluviali = Energetic Recover of River Biomasses). The project concerns the modeling, realization and experimental validation of innovative pathways for the exploitation of grass and woodsy biomasses from river maintenance operations. The project is focused on the Secchia river situated in the mid North of Italy. The final goal is to make the river maintenance operations self-sustainability from the economic and environmental point of views. During the first year of the project, the typical biomasses of the Secchia river was recognized and quantified. Poplar was chosen as major representative of the wood biomasses. An evaluation about wood biomass quantity obtainable for every hectare of riverbanks maintenance was made. Several gasification tests of poplar wood chips from river maintenance was done in a small CHP gasifier. The biochar obtained was characterized and it was applied on field to some giant reed plantations in order to evaluate if there will be a productivity increase with biochar as soil amendant. In addition, a model to evaluate the giant reed annual productivity in the Secchia river banks was developed.

2017 - The use of on-line colorimetry for tar content evaluation in gasification systems [Articolo su rivista]
Quinlan, Brendan; Kaufmann, Bear; Allesina, Giulio; Pedrazzi, Simone; Hasty, Julia; Puglia, Marco; Morselli, Nicolò; Tartarini, Paolo

Gasification of biomass has the potential to become a relevant technology for a sustainable future. However, the content of tar in the gas produced through gasification needs to be managed properly in order to increase the reliability of the technology. Accurate measurement of tar gas concentrations enables management and technology improvement. Standardized offline measurement methods require a long time to produce a numerical result from a test. This work presents a novel colorimetric method to assess the tar concentration contained in syngas. The method uses an apparatus that includes a heated thimble filter (to remove particulate), gas quenching with isopropyl alcohol (IPA), a vapor knockout and cooling system including a final stage fritted glass bubbler/impinger, IPA removal via a peristaltic pump controlled by a capacitive level sensor, IPA flow metering, colorimeter for IPA/tar solution light absorbance measurement, and gas pumping/metering circuit. The method is robust and fast because it is based on a continuous light absorbance measurement. The system was compared against the tar protocol standard showing good correlation between average absorbance and tar concentration. Results demonstrate the capability of the proposed method to give continuous real-time measurement of the tar concentration in the gas.

2017 - Vine prunings biomass as fuel in wood stoves for thermal power production [Articolo su rivista]
Puglia, Marco; Pedrazzi, Simone; Allesina, Giulio; Morselli, Nicolò; Tartarini, Paolo

Wine industries by-products consist in various biomasses. The major in abundance are the vine prunings, derived from the annual vine plant maintenance. Literature suggests a variable production of 1-5 ton/year for every hectare of vine plantation. Vine prunings have a higher heating value of about 18 MJ/kg and an ash amount of about 4%. This paper analyzes the behavior as solid fuel in domestic stove of 4 variety of vine prunings from Emilia Romagna, a region in the north of Italy. First, physical and chemical characterization of the biomass samples were performed, then ash sintering and melting temperatures were evaluated. Combustion tests on a commercial multi-fuel biomass stove were performed. During the tests, mean combustion temperatures, biomass consumption, thermal power and combustion efficiency were calculated and compared with data regarding tests with A1 plus wood pellets. In addition, qualitative results about biomass sintering and stove flame stability was discussed. Results show a thermal efficiency comparable to the one obtained with wood pellet and the sintering of ashes was neglectable. Concluding, pre-treated vine prunings confirmed good properties as fuel in wood stove.

2016 - Modified diesel engine fueled by syngas: Modeling and experimental validation [Relazione in Atti di Convegno]
Pedrazzi, Simone; Allesina, Giulio; Morselli, Nicolò; Puglia, Marco; Rinaldini, Carlo Alberto; Savioli, Tommaso; Mattarelli, Enrico; Giorgini, Loris; Tartarini, Paolo

Diesel engines are robust and reliable machine for stationary electrical energy production. In fact, these engines are designed to run continuously for thousands of hours and with low maintenance. However, several issues affect the application of syngas as fuel in this kind of engines. The full conversion from diesel to gas fuel need the presence of the spark plug instead of the diesel injection. Therefore, the high compression ratio in this kind of engines increase the possibility of the knocking phenomenon inside the combustion chamber. The knocking damages the engine mechanical structure and reduce the engine reliability. Several works set the limit of the compression ratio to 17 in order to overcome this issue. In addition, the velocity of the syngas combustion flame is higher compared to the diesel one as result to the presence of hydrogen in the syngas. This difference forces to reduce the spark ignition time from 0 to 15 ° in advance respect the Bottom Top Dead Center (BTDC) in order to limit the peak pressure inside the cylinders to the design value of the engine. Aim of this work is to compare results of a 0D mathematical model of a converted diesel engine with the results obtained in an experimental campaign. For the tests a Fiat Power Train (FPT) 4.5 liters commercial diesel engine converted to syngas is used. The model calculates the maximum power output of the engine at different rpm starting from syngas composition, airsyngas mixture temperature and diesel nominal power. The model takes into account the friction losses, air to fuel ratio and intake manifold pressure. Experimental tests were run on a gasification facility consisting in a fixed bed wood chip downdraft gasifier that generates syngas to fuel the FPT engine. The engine is connected to a MeccAlte generator for electrical power production. An Arduino based controller sets the position of the air valve in order to stabilize the lambda value of the exhaust of the engine to 1.05. A variable electrical load was applied and it was increased as long as the engine was able to drag the generator at 1500 rpm. During the tests, the following parameters were monitored: syngas volumetric flow rate and composition, syngas pollutants concentration (tar, particulate and water), air-gas mixture temperature and intake manifold pressure. An HT electrical circuit analyzer recorded the power output of the generator. Several tests were run at 1500 rpm varying the air-syngas mixture temperature and the intake manifold pressure and experimental results was compared to 0D model predictions. A good agreement of the model to experimental data was achieved. Syngas conversion reduces the maximum electrical power output of the engine generator from 49.7 kW to about 22 kW as result of the lower air-syngas mixture calorific value and density compared to diesel-air mixture. However, the engine mechanical efficiency is comparable using syngas or diesel fuel (about 30%) and pollutant emissions are strongly lower with syngas fuel.

2016 - Preliminary Analysis on an Algae-Based Water Scrubber For Syngas [Abstract in Atti di Convegno]
Allesina, Giulio; Pedrazzi, Simone; ALTUNOZ HATIPOGLU, Meltem; Morselli, Nicolo'; Puglia, Marco; Allegretti, Francesco; Leonardi, Chiara; Giorgini, Loris; Arru, Laura; Tartarini, Paolo

In this study, two major advantages of microalga Neochloris oleoabundans have been taken into account: purification of the syngas contaminant water (SCW) and providing biomass yield from microalgae growth by using syngas contaminant together with BG11 microalgal growth medium [1] as a feedstock. 10 kW imbert type downdraft gasifier fueled with wood chips have been used to obtain syngas contaminant [2]. A certain amount of the wood-gas is derived after the biofiltering process and is sent to the Water Algae Photo-Bio-Scrubber System (WAPBS): a series of Drechsel bottles are filled with syngas cleansing water (SCW). Tar and particulate are trapped in the water inside the WAPBS, while part of the syngas contaminant is available for the micro algae to be converted into biomass. At the end of the process char and tar content of the syngas contaminant used by microalgae have been observed and microalgal growth of N. oleoabundans have been monitored during the process of WAPBS.

2016 - Preliminary analyses on an algae-based water scrubber for syngas cleaning [Abstract in Atti di Convegno]
Allesina, Giulio; Pedrazzi, Simone; ALTUNOZ HATIPOGLU, Meltem; Morselli, Nicolo'; Puglia, Marco; Leonardi, Chiara; Giorgini, L; Arru, Laura; Tartarini, Paolo

Aim of this work is to try to put together the two worlds of syngas filtering and syngas upgrading trough the use of a water-algae water photo-bio-scrubber. The system studied consists of a 10 kWel downdraft gasifier provided with a water scrubber where the syngas is bubbled in a solution of water, nutrients, algae and artificial light (. The heat provided by the syngas keeps the scrubber to the proper temperature where tars are condensed and algae can grow at proper rate. At the same time the CO2 content in the gas can be, in part, converted into biomass by the algae. From the scrubber it is disposed a multi-phase liquid composed of water, biomass, tars and char. The first analysis carried out in this work consisted in a two phases process of the gas. First, in the gasification system, part of the gas was derived into a simple water scrubber where all the flows where measured and the temperature was kept constant at 30 °C. Then the water obtained in such a way was used as basis for algae grown in lab conditions. Results shown the capability of such a system to be used in existing gasification facilities.

2016 - Uses of a water-algae-photo-bio-scrubber for syngas upgrading and purification [Relazione in Atti di Convegno]
Allesina, Giulio; Pedrazzi, Simone; Arru, Laura; Altunöz Hatipoğlu, Meltem; Puglia, Marco; Tartarini, Paolo

Aim of this work is to try to put together the two worlds of syngas filtering and syngas upgrading trough the use of a water-algae water photo- bio-scrubber. The system studied consists of a 10 kWel downdraft gasifier provided with a water scrubber where the syngas is bubbled in a solution of water, nutrients, algae and artificial light (. The heat provided by the syngas keeps the scrubber to the proper temperature where tars are condensed and algae can grow at proper rate. At the same time the CO2 content in the gas can be, in part, converted into biomass by the algae. From the scrubber it is disposed a multi-phase liquid composed of water, biomass, tars and char. The first analysis carried out in this work consisted in a two phases process of the gas. First, in the gasification system, part of the gas was derived into a simple water scrubber where all the flows where measured and the temperature was kept constant at 30 °C. Then the water obtained in such a way was used as basis for algae grown in lab conditions. Results shown the capability of such a system to be used in existing gasification facilities.

Allesina, G.; Pedrazzi, S.; Puglia, M.; Tartarini, P.

The classical approach to syngas processing is based on the assumption that the gas stream (composed of H-2, CO2, CO, N-2, CH4 and H2O) carries tars ashes and soot in it. Tars are usually classified as liquid, while the soot and the ashes are evidently considered solid. This approach is undoubtedly valid but needs to be adapted depending on the temperature conditions that continuously change in a typical gasification power plant composed of a reactor, a filtering system and an engine. Particular attention is payed in this work to the water vapor. It is an unavoidable product of the gasification process that origins from the combustion reactions or derives from the biomass moisture. Under the dew point this vapor condensates assisted by the soot and ashes that can act as nuclei for droplets coalescence. The work proposed here uses a chemical equilibrium model for the evaluation of the gas composition varying the biomass moisture content, then the model output is analyzed using the approach typical of psychrometric problems. In this way it was possible to spotlight the limit temperature in the gas line that avoids water condensation. In fact, the temperature cannot be simply increased because, even if this solution prevent condensation, it drastically reduces the engine performance ad even its durability. For this reason, this study takes into account the equations that simplify the engine behavior and, nevertheless, allow us to evaluate the ultimate performance variation produced by the temperature limit imposed by the moisture content in the biomass.

2015 - Increased maize power production through an integrated biogas-gasification-SOFC power system [Relazione in Atti di Convegno]
Pedrazzi, Simone; Allesina, Giulio; Puglia, Marco; Guidetti, Luca; Tartarini, Paolo

This work is aimed at demonstrating by modeling and simulation how a synergy of state-of-the-art technologies can boost of about 50% the maximum power output that can be obtained from maize silage biogas power plants. The starting point is the subdivision of the maize plant into grains and stover (that is composed of cobs, stalks and leaves). Grains are rich of starch, soluble sugars, fat and protein suitable for the anaerobic digestion, instead the stover is rich of hemicellulose and lignin which are characterized by a slow and incomplete degradability. This consideration brings to the core of the paper: grains are used as fuel in an anaerobic digester, while stover is converted into syngas in a fixed bed downdraft gasifier reactor. The biological degradation of grains is based on equilibrium kinetic models obtained from literature review, the stover gasification is modeled with an equilibrium model implemented in Python™ language. Biogas and syngas streams are used together as fuel in a Solid Oxide Fuel Cell (SOFC) conversion unit modeled through a MatlabTM script. Simulations were done considering a conventional maize silage biogas power plant with 100 kW electrical nominal power. Results outlined that the SOFC has a higher conversion rate than the conventional IC engine, in fact the replacement of the generator with a SOFC increases the power output of the plant to about 118 kW. Finally, the combined effects of coupling digestion of grains with the gasification of the stover and the use of a SOFC boost the peaks power output to 150 kW.

2015 - Which thermochemical conversion process for agricultural waste? Physical and chemical analyses to guide the choice [Articolo su rivista]
Pedrazzi, Simone; Allesina, Giulio; Puglia, Marco; Morselli, Nicolò; Tartarini, Paolo

This study investigates how physical and chemical analyses may lead the choice of the more suitable thermochemical energy conversion process for agricultural wastes. Four different case study are presented: corn cobs, digestate pellets from anaerobic digestion, wood biomass from river maintenance and seed cake from vegetable oil production. For all the cases analyzed the physical as well as the chemical characterization of the feedstocks are presented and discussed. Outputs of these analyses are: chemical composition, moisture content, ash content, ash softening point and particle size. These outputs, together with logistic considerations about availability and preconditioning of the biomasses allow to properly define the optimal process for each biomass. Three thermochemical processes are taken into account: pyrolysis, gasification and direct combustion.