Giovanni Cinti | Università degli Studi di Perugia (original) (raw)

Papers by Giovanni Cinti

Pyrolysis of glycerol, a by-product of the biodiesel industry, is an important potential source o... more Pyrolysis of glycerol, a by-product of the biodiesel industry, is an important potential source of hydrogen. The obtained high calorific value gas can be used either as a fuel for combined heat and power (CHP) generation or as a transportation fuel (that is hydrogen to be used in fuel cells). Optimal process conditions can improve glycerol pyrolysis by increasing gas yield and hydrogen concentration. A detailed kinetic mechanism of glycerol pyrolysis, which involves 137 species and more than 4500 reactions, is drastically simplified and reduced to a new skeletal kinetic scheme of 44 species involved in 452 reactions. An experimental campaign with a batch pyrolysis reactor was properly designed to further validate the original and the skeletal mechanisms. Comparisons between model predictions and experimental data strongly suggest the presence of a catalytic process promoting steam reforming of methane. High pyrolysis temperatures (750–800 °C) improve process performances and non-condensable gas yields of 70%w are achieved. Hydrogen mole fraction in pyrolysis gas is about 44–48%v. The skeletal mechanism developed can be easily used in Computational Fluid Dynamic software, reducing the simulation time.

Solid oxide fuel cell-based systems constitute one of the most promising technologies for future ... more Solid oxide fuel cell-based systems constitute one of the most promising technologies for future power generation. In order to make them marketable, many issues as durability and operational management have to be overcome. Therefore the understanding of thermodynamic and chemical mechanisms, that govern SOFC BoP components (beyond that the stack one) behaviour in both steady-state and transient operation, becomes fundamental. In this context, after stack dynamic analysis [1] and investigations relative to SOFC-based systems [2,3], the study was extended to the methane steam reformer unit, with particular attention to its dynamic thermal behaviour. In particular the overall analysis methodology and the required experimental campaign were defined as described in the following. Future work will deal with the execution of all the scheduled tests and the model setup according to the developed methodology.

Applied Energy, 2015

ABSTRACT Solid Oxide Fuel Cell (SOFC) can be operated with a wide variety of fuels and in a large... more ABSTRACT Solid Oxide Fuel Cell (SOFC) can be operated with a wide variety of fuels and in a large range of operating conditions. Taking advantage of high temperature and nickel based catalysts several compounds such as methane, ethanol and ammonia can be internally reformed or thermally decomposed producing hydrogen rich gas streams. In this study urea was investigated as a potential fuel for SOFC, since it is a widely available product in the fertilizers’ market, safe to be handled and used, and can be recovered from biomass or water treatment plants as a byproduct. An additional pathway for green urea can be based on green hydrogen via electrolysis powered by renewable energy sources and CO2 recovered from carbon capture plants. Urea decomposition was studied and reproduced in the experimental activity to evaluate its effect on the performance of SOFCs. A gas stream, obtained by simulating decomposed urea with technical gases mixtures, was fed into an SOFC stack, varying the operational temperature and the steam to carbon ratio. Experimental results produced efficiencies higher than 40%. Based on experimental data a 0-D model was developed and operational conditions were expanded, reaching an overall efficiency of 60%.

Carbon dioxide increase in atmosphere is considered main responsible of greenhouse effect. The bi... more Carbon dioxide increase in atmosphere is considered main responsible of greenhouse effect. The biggest part of CO2 is produced in power plants using fossil fuels. Nowadays there are several technologies applied to concentrate CO2 but each of them consumes part of the electric power generated from the plant. Molten carbonate fuel cell (MCFC) can be used as concentrator of CO2, thanks to the chemical reactions that occurs in the cell stack: carbon dioxide entering into the cathode side is transported to the anode side via CO3= ions and is finally concentrated in the anodic exhaust. MCFC system can be integrated to the power plant, retro fitting, to separate CO2 produced and, at the same time, produce additional energy [1]. Target of this study is to find a feasible system design for medium scale cogeneration plants as far as there is an important increase of centralized generation respect to delocalized generation. This trend, is confirmed, will increase number of medium cogeneration ...

ABSTRACT In the present work preliminary characterization tests, finalized to application as a re... more ABSTRACT In the present work preliminary characterization tests, finalized to application as a residential micro-CHP system, are reported. Through systematic, parallel testing under predetermined conditions, laboratories at ENEA and the University of Perugia aim at establishing the real lifetime expectancy and performance characteristic of 1 kW-class SOFC stacks fed with natural gas from the grid, downstream of a specifically developed desulphurizer for the abatement of odorants. Through the assessment of material response and delivered power also at single cell level, it will be possible to establish and improve the behaviour in time of a SOFC system operated under realistic conditions. There is continuous feedback with both the system optimization engineers as with powder development chemists, in order to bring the concept swiftly and efficiently to market maturity, as well as prepare the basis for second generation systems with improved stack performance and durability.

ABSTRACT Desulfurization represents a crucial step in fuel processing for high temperature fuel c... more ABSTRACT Desulfurization represents a crucial step in fuel processing for high temperature fuel cells, because of catalysts stringent requirements. Moreover, when fuel cell stacks are used in micro-CHP applications, it is necessary to build an efficient and compact system. The use of biogas from anaerobic digestion could have a significant impact in terms of fossil fuels saving and environmental conservation. Biogas contains different impurities, among which H2S represents one of the most harmful components.

ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology, 2011

ABSTRACT Nowadays, in a world characterized by the need to reduce the production of pollutants, b... more ABSTRACT Nowadays, in a world characterized by the need to reduce the production of pollutants, by global climate changes, by the progressive lack of availability of cheap fossil fuels, one of the most important goals of scientific research is to design systems that can provide energy with low environmental impact. Planar Solid Oxide Fuel Cells (SOFC) are considered to be power generators with high efficiency independent on size and low emissions. Fuel cell laboratory (FCLab) of University of Perugia has focused his studies on SOFC operating at high temperature (800–1000°C), characterized by greater flexibility in the choice of fuel. This study focuses on definition and realization of experimental test able to define the quality of a SOFC single cell and on the effect of test condition parameter. The performance of the cell is evaluated via polarization curves realized in different external conditions. Area Specific Resistance (ASR) is used as main test output. Results analysis confirm that ASR gives important information on fuel cell performance and can be used to compare an qualify SOFC single cell.

ECS Transactions, 2013

ABSTRACT In the frame of a common project on the development of prototype micro-cogeneration syst... more ABSTRACT In the frame of a common project on the development of prototype micro-cogeneration systems for household applications, ENEA and FCLAB have characterized a 1kW(el) and a 2.5kW(el) tubular-type SOFC technology-based unit respectively. Spanning the entire operational window of the two systems (within boundary conditions set by safe and durable operation, i.e. limitations on fuel utilization, oxygen-to-carbon ratio, stack and exhaust temperature profiles) the performance and efficiency characteristics of the two systems have been fully mapped. Thus, a technical-economical evaluation can take place for a calculated assessment of the optimal allocation of the two scales of systems.

Energy Procedia, 2014

In this work, the performance of solid oxide fuel cells (SOFCs) fed with a syngas obtained from a... more In this work, the performance of solid oxide fuel cells (SOFCs) fed with a syngas obtained from a steam-enriched air gasification of biomass has been investigated, varying the composition of the feeding gas (H2, CO, CO2, CH4, H2O, and N2). The composition has been obtained from experimental/numerical tests in a fluidized bed bench scale gasifier after catalytic steam reforming of the syngas carried out to remove tar. During the gasification tests, the oxygen purity in the enriched air (in the range of 0.2 and 0.9), the gasification process temperature (in the range of 750 and 850 °C), the steam to biomass (in the range of 0.5 and 1) and the equivalence ratio (in the range between 0.0 and 0.4) were varied to simulate the different operating conditions. Commercial SOFC cells have been employed in the experimental campaign, fed with the most representative fuel compositions mentioned above. Polarization curves have been carried out to determine the electrical performance of the cells, comparing the results with cells fed with hydrogen only. In the final paper, the electrochemical impedance spectroscopy (EIS) will be reported for in-depth analysis of the performance parameters and to evaluate the long term degradation rate of the cell.

Fuel Cells, 2013

ABSTRACT Solid oxide fuel cell (SOFC) is one of the most promising technologies for future power ... more ABSTRACT Solid oxide fuel cell (SOFC) is one of the most promising technologies for future power generation. In order to make this technology marketable, many issues as cost reduction, durability, and operational management have to be overcome. Therefore, the understanding of thermodynamic and electrochemical mechanisms, that govern the SOFC behavior in steady-state and in transient operation, becomes fundamental. In this context, the modeling of fuel cell (FC) thermal transient is of great interest because it can predict the temperature time variation, useful to the dimensioning of auxiliary devices and to avoid unwanted operational states affecting cell durability. In the present study, a 0-D model of SOFC thermal transients was developed by applying system identification techniques, starting from experimental tests carried out on a stack made up of four single cells. Moreover, it was successfully validated in reference to further experimental data. The model allows to evaluate, in term of dynamic response, the effect of the main operating parameters on FC temperature. As further result, some control/regulation considerations useful to limit thermal stresses were proposed.

Fuel Cells, 2014

ABSTRACT In this study, ammonia is presented as a feasible fuel for solid oxide fuel cells (SOFCs... more ABSTRACT In this study, ammonia is presented as a feasible fuel for solid oxide fuel cells (SOFCs). Ammonia has several interesting features as fuel due to low-production cost, high-energy density and, focusing on fuel cells and hydrogen application, ammonia is an excellent H2 carrier thanks to high value of volumetric and gravimetric densities. The paper reports experimental test performed to evaluate the feasibility of NH3 directly fed to a 50 cm2 single cell SOFC. A test plan was developed to compare pure ammonia with an equivalent mix of ammonia, nitrogen, and hydrogen and the study of temperature and voltage values strongly indicates that a two stage oxidation of ammonia can be predicted and a previous cracking reaction occurs in the cell due to the nickel catalytic contribution. The study of temperatures and of heat flows show how the cell is cooled down to lower temperature because of heat adsorbed by the reaction and by flow mix entering the anode. The study shows also how for operative temperatures below 800 °C the cracking reaction takes place in the cell active area. Efficiency test demonstrates that the cell can operate at 300 mW cm–2 and 30% efficiency based on ammonia LHV.

International Journal of Hydrogen Energy, 2014

With the explosive growth of high-data rate multimedia services and machine-to-machine (M2M) type... more With the explosive growth of high-data rate multimedia services and machine-to-machine (M2M) type communications, numerous small cells will be densely deployed in future fifth generation wireless network, resulting in serious interference, intolerable delay, and huge handover failure. Massive access M2M services, with low-rate high-frequency requests, will also generate much signaling overhead costs and cause enormous waste of system resources. In the Third Generation Partnership Project, the split of control and user (C/U) planes is perceived as one of the most promising methods for small cell enhancement to address these challenges. In this article, a new C/U split architecture of data-only carrier (DoC) system is analyzed comprehensively from various aspects, such as overhead costs, coverage probability, spectral efficiency, and energy efficiency for the first time. Based on the model of stochastic geometry, the influences of density and power of small cell and cell range expansion factors are all taken into account to compare the DoC architecture with the baseline long-term evolution (LTE) system. Numerical results show that the DoC system can greatly reduce the overhead costs and help to achieve higher throughput gain and better coverage performance over the conventional LTE system. a severe challenge for future networks . In the future, the cellular network has to manage up to 10-100 times more devices and provide lower latency to milliseconds to ensure reliability, especially in new services like vehicular networking technology and applications [1]. These machine-type communications with small-sized persistent burst traffic services will be burdening the wireless access and core network, lowering the sleeping probability of base stations (BSs) and wasting many bandwidth resources.

Pyrolysis of glycerol, a by-product of the biodiesel industry, is an important potential source o... more Pyrolysis of glycerol, a by-product of the biodiesel industry, is an important potential source of hydrogen. The obtained high calorific value gas can be used either as a fuel for combined heat and power (CHP) generation or as a transportation fuel (that is hydrogen to be used in fuel cells). Optimal process conditions can improve glycerol pyrolysis by increasing gas yield and hydrogen concentration. A detailed kinetic mechanism of glycerol pyrolysis, which involves 137 species and more than 4500 reactions, is drastically simplified and reduced to a new skeletal kinetic scheme of 44 species involved in 452 reactions. An experimental campaign with a batch pyrolysis reactor was properly designed to further validate the original and the skeletal mechanisms. Comparisons between model predictions and experimental data strongly suggest the presence of a catalytic process promoting steam reforming of methane. High pyrolysis temperatures (750–800 °C) improve process performances and non-condensable gas yields of 70%w are achieved. Hydrogen mole fraction in pyrolysis gas is about 44–48%v. The skeletal mechanism developed can be easily used in Computational Fluid Dynamic software, reducing the simulation time.

Solid oxide fuel cell-based systems constitute one of the most promising technologies for future ... more Solid oxide fuel cell-based systems constitute one of the most promising technologies for future power generation. In order to make them marketable, many issues as durability and operational management have to be overcome. Therefore the understanding of thermodynamic and chemical mechanisms, that govern SOFC BoP components (beyond that the stack one) behaviour in both steady-state and transient operation, becomes fundamental. In this context, after stack dynamic analysis [1] and investigations relative to SOFC-based systems [2,3], the study was extended to the methane steam reformer unit, with particular attention to its dynamic thermal behaviour. In particular the overall analysis methodology and the required experimental campaign were defined as described in the following. Future work will deal with the execution of all the scheduled tests and the model setup according to the developed methodology.

Applied Energy, 2015

ABSTRACT Solid Oxide Fuel Cell (SOFC) can be operated with a wide variety of fuels and in a large... more ABSTRACT Solid Oxide Fuel Cell (SOFC) can be operated with a wide variety of fuels and in a large range of operating conditions. Taking advantage of high temperature and nickel based catalysts several compounds such as methane, ethanol and ammonia can be internally reformed or thermally decomposed producing hydrogen rich gas streams. In this study urea was investigated as a potential fuel for SOFC, since it is a widely available product in the fertilizers’ market, safe to be handled and used, and can be recovered from biomass or water treatment plants as a byproduct. An additional pathway for green urea can be based on green hydrogen via electrolysis powered by renewable energy sources and CO2 recovered from carbon capture plants. Urea decomposition was studied and reproduced in the experimental activity to evaluate its effect on the performance of SOFCs. A gas stream, obtained by simulating decomposed urea with technical gases mixtures, was fed into an SOFC stack, varying the operational temperature and the steam to carbon ratio. Experimental results produced efficiencies higher than 40%. Based on experimental data a 0-D model was developed and operational conditions were expanded, reaching an overall efficiency of 60%.

Carbon dioxide increase in atmosphere is considered main responsible of greenhouse effect. The bi... more Carbon dioxide increase in atmosphere is considered main responsible of greenhouse effect. The biggest part of CO2 is produced in power plants using fossil fuels. Nowadays there are several technologies applied to concentrate CO2 but each of them consumes part of the electric power generated from the plant. Molten carbonate fuel cell (MCFC) can be used as concentrator of CO2, thanks to the chemical reactions that occurs in the cell stack: carbon dioxide entering into the cathode side is transported to the anode side via CO3= ions and is finally concentrated in the anodic exhaust. MCFC system can be integrated to the power plant, retro fitting, to separate CO2 produced and, at the same time, produce additional energy [1]. Target of this study is to find a feasible system design for medium scale cogeneration plants as far as there is an important increase of centralized generation respect to delocalized generation. This trend, is confirmed, will increase number of medium cogeneration ...

ABSTRACT In the present work preliminary characterization tests, finalized to application as a re... more ABSTRACT In the present work preliminary characterization tests, finalized to application as a residential micro-CHP system, are reported. Through systematic, parallel testing under predetermined conditions, laboratories at ENEA and the University of Perugia aim at establishing the real lifetime expectancy and performance characteristic of 1 kW-class SOFC stacks fed with natural gas from the grid, downstream of a specifically developed desulphurizer for the abatement of odorants. Through the assessment of material response and delivered power also at single cell level, it will be possible to establish and improve the behaviour in time of a SOFC system operated under realistic conditions. There is continuous feedback with both the system optimization engineers as with powder development chemists, in order to bring the concept swiftly and efficiently to market maturity, as well as prepare the basis for second generation systems with improved stack performance and durability.

ABSTRACT Desulfurization represents a crucial step in fuel processing for high temperature fuel c... more ABSTRACT Desulfurization represents a crucial step in fuel processing for high temperature fuel cells, because of catalysts stringent requirements. Moreover, when fuel cell stacks are used in micro-CHP applications, it is necessary to build an efficient and compact system. The use of biogas from anaerobic digestion could have a significant impact in terms of fossil fuels saving and environmental conservation. Biogas contains different impurities, among which H2S represents one of the most harmful components.

ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology, 2011

ABSTRACT Nowadays, in a world characterized by the need to reduce the production of pollutants, b... more ABSTRACT Nowadays, in a world characterized by the need to reduce the production of pollutants, by global climate changes, by the progressive lack of availability of cheap fossil fuels, one of the most important goals of scientific research is to design systems that can provide energy with low environmental impact. Planar Solid Oxide Fuel Cells (SOFC) are considered to be power generators with high efficiency independent on size and low emissions. Fuel cell laboratory (FCLab) of University of Perugia has focused his studies on SOFC operating at high temperature (800–1000°C), characterized by greater flexibility in the choice of fuel. This study focuses on definition and realization of experimental test able to define the quality of a SOFC single cell and on the effect of test condition parameter. The performance of the cell is evaluated via polarization curves realized in different external conditions. Area Specific Resistance (ASR) is used as main test output. Results analysis confirm that ASR gives important information on fuel cell performance and can be used to compare an qualify SOFC single cell.

ECS Transactions, 2013

ABSTRACT In the frame of a common project on the development of prototype micro-cogeneration syst... more ABSTRACT In the frame of a common project on the development of prototype micro-cogeneration systems for household applications, ENEA and FCLAB have characterized a 1kW(el) and a 2.5kW(el) tubular-type SOFC technology-based unit respectively. Spanning the entire operational window of the two systems (within boundary conditions set by safe and durable operation, i.e. limitations on fuel utilization, oxygen-to-carbon ratio, stack and exhaust temperature profiles) the performance and efficiency characteristics of the two systems have been fully mapped. Thus, a technical-economical evaluation can take place for a calculated assessment of the optimal allocation of the two scales of systems.

Energy Procedia, 2014

In this work, the performance of solid oxide fuel cells (SOFCs) fed with a syngas obtained from a... more In this work, the performance of solid oxide fuel cells (SOFCs) fed with a syngas obtained from a steam-enriched air gasification of biomass has been investigated, varying the composition of the feeding gas (H2, CO, CO2, CH4, H2O, and N2). The composition has been obtained from experimental/numerical tests in a fluidized bed bench scale gasifier after catalytic steam reforming of the syngas carried out to remove tar. During the gasification tests, the oxygen purity in the enriched air (in the range of 0.2 and 0.9), the gasification process temperature (in the range of 750 and 850 °C), the steam to biomass (in the range of 0.5 and 1) and the equivalence ratio (in the range between 0.0 and 0.4) were varied to simulate the different operating conditions. Commercial SOFC cells have been employed in the experimental campaign, fed with the most representative fuel compositions mentioned above. Polarization curves have been carried out to determine the electrical performance of the cells, comparing the results with cells fed with hydrogen only. In the final paper, the electrochemical impedance spectroscopy (EIS) will be reported for in-depth analysis of the performance parameters and to evaluate the long term degradation rate of the cell.

Fuel Cells, 2013

ABSTRACT Solid oxide fuel cell (SOFC) is one of the most promising technologies for future power ... more ABSTRACT Solid oxide fuel cell (SOFC) is one of the most promising technologies for future power generation. In order to make this technology marketable, many issues as cost reduction, durability, and operational management have to be overcome. Therefore, the understanding of thermodynamic and electrochemical mechanisms, that govern the SOFC behavior in steady-state and in transient operation, becomes fundamental. In this context, the modeling of fuel cell (FC) thermal transient is of great interest because it can predict the temperature time variation, useful to the dimensioning of auxiliary devices and to avoid unwanted operational states affecting cell durability. In the present study, a 0-D model of SOFC thermal transients was developed by applying system identification techniques, starting from experimental tests carried out on a stack made up of four single cells. Moreover, it was successfully validated in reference to further experimental data. The model allows to evaluate, in term of dynamic response, the effect of the main operating parameters on FC temperature. As further result, some control/regulation considerations useful to limit thermal stresses were proposed.

Fuel Cells, 2014

ABSTRACT In this study, ammonia is presented as a feasible fuel for solid oxide fuel cells (SOFCs... more ABSTRACT In this study, ammonia is presented as a feasible fuel for solid oxide fuel cells (SOFCs). Ammonia has several interesting features as fuel due to low-production cost, high-energy density and, focusing on fuel cells and hydrogen application, ammonia is an excellent H2 carrier thanks to high value of volumetric and gravimetric densities. The paper reports experimental test performed to evaluate the feasibility of NH3 directly fed to a 50 cm2 single cell SOFC. A test plan was developed to compare pure ammonia with an equivalent mix of ammonia, nitrogen, and hydrogen and the study of temperature and voltage values strongly indicates that a two stage oxidation of ammonia can be predicted and a previous cracking reaction occurs in the cell due to the nickel catalytic contribution. The study of temperatures and of heat flows show how the cell is cooled down to lower temperature because of heat adsorbed by the reaction and by flow mix entering the anode. The study shows also how for operative temperatures below 800 °C the cracking reaction takes place in the cell active area. Efficiency test demonstrates that the cell can operate at 300 mW cm–2 and 30% efficiency based on ammonia LHV.

International Journal of Hydrogen Energy, 2014

With the explosive growth of high-data rate multimedia services and machine-to-machine (M2M) type... more With the explosive growth of high-data rate multimedia services and machine-to-machine (M2M) type communications, numerous small cells will be densely deployed in future fifth generation wireless network, resulting in serious interference, intolerable delay, and huge handover failure. Massive access M2M services, with low-rate high-frequency requests, will also generate much signaling overhead costs and cause enormous waste of system resources. In the Third Generation Partnership Project, the split of control and user (C/U) planes is perceived as one of the most promising methods for small cell enhancement to address these challenges. In this article, a new C/U split architecture of data-only carrier (DoC) system is analyzed comprehensively from various aspects, such as overhead costs, coverage probability, spectral efficiency, and energy efficiency for the first time. Based on the model of stochastic geometry, the influences of density and power of small cell and cell range expansion factors are all taken into account to compare the DoC architecture with the baseline long-term evolution (LTE) system. Numerical results show that the DoC system can greatly reduce the overhead costs and help to achieve higher throughput gain and better coverage performance over the conventional LTE system. a severe challenge for future networks . In the future, the cellular network has to manage up to 10-100 times more devices and provide lower latency to milliseconds to ensure reliability, especially in new services like vehicular networking technology and applications [1]. These machine-type communications with small-sized persistent burst traffic services will be burdening the wireless access and core network, lowering the sleeping probability of base stations (BSs) and wasting many bandwidth resources.