Elisangela M Leal | Universidade Federal de Ouro Preto (original) (raw)

Papers by Elisangela M Leal

International Journal of Applied Power Engineering, Mar 1, 2021

The relatively high operating temperature of the solid oxide fuel cell allows for a highly effici... more The relatively high operating temperature of the solid oxide fuel cell allows for a highly efficient conversion to power, internal reforming, and high-quality by-product heat for cogeneration or a bottoming cycle. Besides, high-temperature fuel cells offer a good opportunity for coupling to a gas turbine. Fuel cell systems have demonstrated minimal air pollutant emissions and low greenhouse gas emissions. This paper focuses on the investigation and technical analysis of a direct internal reforming solid oxide fuel cell (DIR-SOFC) and a gas turbine (GT) system. The technical analysis comprises of an energy and exergy analysis of the hybrid cycle, using the Gibbs function minimization technique for the methane steam reforming process. The assessment is performed to determine the influence of the hybrid cycle operating temperature and pressure, steam-to-carbon ratio and fuel and oxidant usage in the fuel cell. Equilibrium calculations are made to find the ranges of inlet steam-tocarbon ratio and the operating current density of the fuel cell. After that, a hybrid system consists of a DIR-SOFC and a GT is evaluated using computer simulation. The results showed that the fuel cell is the main power producer system at the design point. The high-energy efficiency (around 62%) and exergy efficiency (around 58%) are achieved by the hybrid cycle compared to fuel cell efficiency (about 40%) and the GT (around 38%). The power ratio (SOFC/GT) found was 1.50. An analysis varying the fuel cell current density and the GT pressure ratio was performed showing that the fuel cell power production decreases about 7% with increasing current density when the GT becomes the main power-producing equipment. However, the system energy efficiency decreases with the reduction of power produced by the fuel cell.

À Deus-razão de toda a existência, fonte de esperança e amor-, por ter me guiado para alcançar ma... more À Deus-razão de toda a existência, fonte de esperança e amor-, por ter me guiado para alcançar mais esta graça. Ao professor Reginaldo Teixeira Coelho, pela confiança, pela excelente orientação, pela amizade e paciência. À Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), pelo apoio financeiro.

This paper presents: (1) the electricity and hydrogen co-production concept, (2) a thermodynamic ... more This paper presents: (1) the electricity and hydrogen co-production concept, (2) a thermodynamic analysis methodology for studying solid oxide and molten carbonate fuel cell hydrogen co-production, and (3) simulation results that address the impact of reformer placement in the cycle on system performance. The methodology is based on detailed thermodynamic and electrochemical principles that apply to each of the system components and the integrated cycles. Eight different cycle configurations that use fuel cell heat to drive hydrogen production in a reformer are proposed, analyzed, and compared. The specific cycle configurations include SOFC and MCFC cycles using both external and internal reforming options. The fuel cell plant performance has been evaluated on the basis of methane utilization efficiency and each component of the plant has been evaluated on the basis of second law efficiency. The analyses show that in all cases the exergy losses (irreversibilities) in the combustion chamber are the most significant losses in the cycle. Furthermore, for the same power output, the internal reformation option has the higher electrical efficiency and produces more hydrogen per unit of fuel supplied, in the case of using a SOFC.

Energy Conversion and Management, Dec 1, 2019

The relatively high operating temperature of the solid oxide fuel cell allows for a highly effici... more The relatively high operating temperature of the solid oxide fuel cell allows for a highly efficient conversion to power, internal reforming, and high-quality by-product heat for cogeneration or a bottoming cycle. Besides, high-temperature fuel cells offer a good opportunity for coupling to a gas turbine. Fuel cell systems have demonstrated minimal air pollutant emissions and low greenhouse gas emissions. This paper focuses on the investigation and technical analysis of a direct internal reforming solid oxide fuel cell (DIR-SOFC) and a gas turbine (GT) system. The technical analysis comprises of an energy and exergy analysis of the hybrid cycle, using the Gibbs function minimization technique for the methane steam reforming process. The assessment is performed to determine the influence of the hybrid cycle operating temperature and pressure, steam-to-carbon ratio and fuel and oxidant usage in the fuel cell. Equilibrium calculations are made to find the ranges of inlet steam-tocarbon ratio and the operating current density of the fuel cell. After that, a hybrid system consists of a DIR-SOFC and a GT is evaluated using computer simulation. The results showed that the fuel cell is the main power producer system at the design point. The high-energy efficiency (around 62%) and exergy efficiency (around 58%) are achieved by the hybrid cycle compared to fuel cell efficiency (about 40%) and the GT (around 38%). The power ratio (SOFC/GT) found was 1.50. An analysis varying the fuel cell current density and the GT pressure ratio was performed showing that the fuel cell power production decreases about 7% with increasing current density when the GT becomes the main power-producing equipment. However, the system energy efficiency decreases with the reduction of power produced by the fuel cell.

Applied Thermal Engineering, Sep 1, 2002

In this paper, a thermoeconomic analysis method based on the First and the Second Law of Thermody... more In this paper, a thermoeconomic analysis method based on the First and the Second Law of Thermodynamics and applied to analyse the replacement of an equipment of a cogeneration system is presented. The cogeneration system consists of a gas turbine linked to a waste boiler. The electrical demand of the campus is approximately 9 MW but the cogen system generates

Modo de acesso: World Wide Web Inclui bibliografia 1. Engenharia 2. Educação.I. Título CDD-620 O ... more Modo de acesso: World Wide Web Inclui bibliografia 1. Engenharia 2. Educação.I. Título CDD-620 O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos seus respectivos autores.

Procceedings of the 19th Brazilian Congress of Thermal Sciences and Engineering, 2022

Heat Transfer: Volume 1, 2000

In this paper, a methodology for the study of a molten carbonate fuel cell cogeneration system an... more In this paper, a methodology for the study of a molten carbonate fuel cell cogeneration system and applied to a computer center building is developed. This system permits the recovery of waste heat, available between 600°C and 700°C, which can be used to the production of steam, hot and cold water, hot and cold air, depending on the recuperation equipment associated. Initially, some technical information about the most diffusing types of the fuel cell demonstration in the world are presented. In conclusion, the fuel cell cogeneration system may have an excellent opportunity to strengthen the decentralized energy production in the Brazilian tertiary sector.

Journal of Power and Energy Engineering, 2018

This paper aims to evaluate the diesel oil consumption between 2008 and 2015 in the production of... more This paper aims to evaluate the diesel oil consumption between 2008 and 2015 in the production of iron ore in Brazil, creating correlations between energy intensity (production), economy and checking the impact of fuel prices on the commodity. During the analyzed period, the years 2008-2009 indicated economic crises, which interfered in the price and the commercialization of iron ore products. The physical intensity was 0.2% higher than the economic intensity. In the period from 2010 to 2014, economic activity remained more stable, with a decreasing trend, mainly due to the increase of iron ore prices. The physical intensity is much higher than the economic intensity influenced by the expansion of the Chinese economy. The year of 2014 indicated the end of the high iron ore price cycle and the beginning of supply and demand stabilization with consequent reduction in prices. In 2015, the market entered the stabilization phase, with a continuous reduction in unit production costs and transportation logistics. There was an abrupt change due to the strong increase of the economic intensity due to the fall of the international prices of iron ore. The diesel oil consumption plays a vital role in the scenario of cost reduction in iron ore production and a deeper analysis must be done in order to discover some options to change the energy matrix.

Renewable Energy, 2004

ABSTRACT

International Journal of Applied Power Engineering, Jun 1, 2021

Advanced Energy Systems, 2003

In this paper, a methodology for the study of a fuel cell cogeneration system and applied to a un... more In this paper, a methodology for the study of a fuel cell cogeneration system and applied to a university campus is developed. The cogeneration system consists of a molten carbonate fuel cell associated to an absorption refrigeration system. The electrical and cold-water demands of the campus are about 1,000 kW and 1,840 kW (at 7°C), respectively. The energy, exergy and economic analyses are presented. This system uses natural gas as the fuel and operates on electric party. In conclusion, the fuel cell cogeneration system may have an excellent opportunity to strengthen the decentralized energy production in the Brazilian tertiary sector.Copyright © 2003 by ASME

Applied Thermal Engineering, Apr 1, 2015

h i g h l i g h t s A theoretical study of a cogeneration system was carried out. The study was a... more h i g h l i g h t s A theoretical study of a cogeneration system was carried out. The study was applied to an electric arc furnace steelmaking process. The ultimate analysis was used to determine the lower calorific value of the biomass materials. The study used a Rankine cycle and applied the First Law of Thermodynamics. Biomass can replace natural gas in the EAF steelmaking process.

Procceedings of the 19th Brazilian Congress of Thermal Sciences and Engineering, 2022

This paper presents the electricity and hydrogen co-production concept, a methodology for the stu... more This paper presents the electricity and hydrogen co-production concept, a methodology for the study of SOFC hydrogen co-production, and simulation results that address the impact of reformer placement in the cycle on system performance. The methodology is based on detailed thermodynamic and electrochemical analyses of the systems. A comparison is made between six specific cycle configurations, which use fuel cell heat to drive hydrogen production in a reformer using both external and internal reforming options. SOFC plant performance has been evaluated on the basis of methane fuel utilization efficiency and each component of the plant has been evaluated on the basis of second law efficiency. The analyses show that in all cases the exergy losses (irreversibilities) in the combustion chamber are the most significant losses in the cycle. Furthermore, for the same power output, the internal reformation option has the higher electrical efficiency and produces more hydrogen per unit of natural gas supplied. Electrical efficiency of the proposed cycles ranges from 41 to 44%, while overall efficiency (based on combined electricity and hydrogen products) ranges from 45 to 80%. The internal reforming case (steam-to-carbon ratio of 3.0) had the highest overall and electrical efficiency (80 and 45% respectively), but lower second law efficiency (61%), indicating potential for cycle improvements.

Social Science Research Network, 2022

International Journal of Applied Power Engineering, Mar 1, 2021

The relatively high operating temperature of the solid oxide fuel cell allows for a highly effici... more The relatively high operating temperature of the solid oxide fuel cell allows for a highly efficient conversion to power, internal reforming, and high-quality by-product heat for cogeneration or a bottoming cycle. Besides, high-temperature fuel cells offer a good opportunity for coupling to a gas turbine. Fuel cell systems have demonstrated minimal air pollutant emissions and low greenhouse gas emissions. This paper focuses on the investigation and technical analysis of a direct internal reforming solid oxide fuel cell (DIR-SOFC) and a gas turbine (GT) system. The technical analysis comprises of an energy and exergy analysis of the hybrid cycle, using the Gibbs function minimization technique for the methane steam reforming process. The assessment is performed to determine the influence of the hybrid cycle operating temperature and pressure, steam-to-carbon ratio and fuel and oxidant usage in the fuel cell. Equilibrium calculations are made to find the ranges of inlet steam-tocarbon ratio and the operating current density of the fuel cell. After that, a hybrid system consists of a DIR-SOFC and a GT is evaluated using computer simulation. The results showed that the fuel cell is the main power producer system at the design point. The high-energy efficiency (around 62%) and exergy efficiency (around 58%) are achieved by the hybrid cycle compared to fuel cell efficiency (about 40%) and the GT (around 38%). The power ratio (SOFC/GT) found was 1.50. An analysis varying the fuel cell current density and the GT pressure ratio was performed showing that the fuel cell power production decreases about 7% with increasing current density when the GT becomes the main power-producing equipment. However, the system energy efficiency decreases with the reduction of power produced by the fuel cell.

À Deus-razão de toda a existência, fonte de esperança e amor-, por ter me guiado para alcançar ma... more À Deus-razão de toda a existência, fonte de esperança e amor-, por ter me guiado para alcançar mais esta graça. Ao professor Reginaldo Teixeira Coelho, pela confiança, pela excelente orientação, pela amizade e paciência. À Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), pelo apoio financeiro.

This paper presents: (1) the electricity and hydrogen co-production concept, (2) a thermodynamic ... more This paper presents: (1) the electricity and hydrogen co-production concept, (2) a thermodynamic analysis methodology for studying solid oxide and molten carbonate fuel cell hydrogen co-production, and (3) simulation results that address the impact of reformer placement in the cycle on system performance. The methodology is based on detailed thermodynamic and electrochemical principles that apply to each of the system components and the integrated cycles. Eight different cycle configurations that use fuel cell heat to drive hydrogen production in a reformer are proposed, analyzed, and compared. The specific cycle configurations include SOFC and MCFC cycles using both external and internal reforming options. The fuel cell plant performance has been evaluated on the basis of methane utilization efficiency and each component of the plant has been evaluated on the basis of second law efficiency. The analyses show that in all cases the exergy losses (irreversibilities) in the combustion chamber are the most significant losses in the cycle. Furthermore, for the same power output, the internal reformation option has the higher electrical efficiency and produces more hydrogen per unit of fuel supplied, in the case of using a SOFC.

Energy Conversion and Management, Dec 1, 2019

The relatively high operating temperature of the solid oxide fuel cell allows for a highly effici... more The relatively high operating temperature of the solid oxide fuel cell allows for a highly efficient conversion to power, internal reforming, and high-quality by-product heat for cogeneration or a bottoming cycle. Besides, high-temperature fuel cells offer a good opportunity for coupling to a gas turbine. Fuel cell systems have demonstrated minimal air pollutant emissions and low greenhouse gas emissions. This paper focuses on the investigation and technical analysis of a direct internal reforming solid oxide fuel cell (DIR-SOFC) and a gas turbine (GT) system. The technical analysis comprises of an energy and exergy analysis of the hybrid cycle, using the Gibbs function minimization technique for the methane steam reforming process. The assessment is performed to determine the influence of the hybrid cycle operating temperature and pressure, steam-to-carbon ratio and fuel and oxidant usage in the fuel cell. Equilibrium calculations are made to find the ranges of inlet steam-tocarbon ratio and the operating current density of the fuel cell. After that, a hybrid system consists of a DIR-SOFC and a GT is evaluated using computer simulation. The results showed that the fuel cell is the main power producer system at the design point. The high-energy efficiency (around 62%) and exergy efficiency (around 58%) are achieved by the hybrid cycle compared to fuel cell efficiency (about 40%) and the GT (around 38%). The power ratio (SOFC/GT) found was 1.50. An analysis varying the fuel cell current density and the GT pressure ratio was performed showing that the fuel cell power production decreases about 7% with increasing current density when the GT becomes the main power-producing equipment. However, the system energy efficiency decreases with the reduction of power produced by the fuel cell.

Applied Thermal Engineering, Sep 1, 2002

In this paper, a thermoeconomic analysis method based on the First and the Second Law of Thermody... more In this paper, a thermoeconomic analysis method based on the First and the Second Law of Thermodynamics and applied to analyse the replacement of an equipment of a cogeneration system is presented. The cogeneration system consists of a gas turbine linked to a waste boiler. The electrical demand of the campus is approximately 9 MW but the cogen system generates

Modo de acesso: World Wide Web Inclui bibliografia 1. Engenharia 2. Educação.I. Título CDD-620 O ... more Modo de acesso: World Wide Web Inclui bibliografia 1. Engenharia 2. Educação.I. Título CDD-620 O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos seus respectivos autores.

Procceedings of the 19th Brazilian Congress of Thermal Sciences and Engineering, 2022

Heat Transfer: Volume 1, 2000

In this paper, a methodology for the study of a molten carbonate fuel cell cogeneration system an... more In this paper, a methodology for the study of a molten carbonate fuel cell cogeneration system and applied to a computer center building is developed. This system permits the recovery of waste heat, available between 600°C and 700°C, which can be used to the production of steam, hot and cold water, hot and cold air, depending on the recuperation equipment associated. Initially, some technical information about the most diffusing types of the fuel cell demonstration in the world are presented. In conclusion, the fuel cell cogeneration system may have an excellent opportunity to strengthen the decentralized energy production in the Brazilian tertiary sector.

Journal of Power and Energy Engineering, 2018

This paper aims to evaluate the diesel oil consumption between 2008 and 2015 in the production of... more This paper aims to evaluate the diesel oil consumption between 2008 and 2015 in the production of iron ore in Brazil, creating correlations between energy intensity (production), economy and checking the impact of fuel prices on the commodity. During the analyzed period, the years 2008-2009 indicated economic crises, which interfered in the price and the commercialization of iron ore products. The physical intensity was 0.2% higher than the economic intensity. In the period from 2010 to 2014, economic activity remained more stable, with a decreasing trend, mainly due to the increase of iron ore prices. The physical intensity is much higher than the economic intensity influenced by the expansion of the Chinese economy. The year of 2014 indicated the end of the high iron ore price cycle and the beginning of supply and demand stabilization with consequent reduction in prices. In 2015, the market entered the stabilization phase, with a continuous reduction in unit production costs and transportation logistics. There was an abrupt change due to the strong increase of the economic intensity due to the fall of the international prices of iron ore. The diesel oil consumption plays a vital role in the scenario of cost reduction in iron ore production and a deeper analysis must be done in order to discover some options to change the energy matrix.

Renewable Energy, 2004

ABSTRACT

International Journal of Applied Power Engineering, Jun 1, 2021

Advanced Energy Systems, 2003

In this paper, a methodology for the study of a fuel cell cogeneration system and applied to a un... more In this paper, a methodology for the study of a fuel cell cogeneration system and applied to a university campus is developed. The cogeneration system consists of a molten carbonate fuel cell associated to an absorption refrigeration system. The electrical and cold-water demands of the campus are about 1,000 kW and 1,840 kW (at 7°C), respectively. The energy, exergy and economic analyses are presented. This system uses natural gas as the fuel and operates on electric party. In conclusion, the fuel cell cogeneration system may have an excellent opportunity to strengthen the decentralized energy production in the Brazilian tertiary sector.Copyright © 2003 by ASME

Applied Thermal Engineering, Apr 1, 2015

h i g h l i g h t s A theoretical study of a cogeneration system was carried out. The study was a... more h i g h l i g h t s A theoretical study of a cogeneration system was carried out. The study was applied to an electric arc furnace steelmaking process. The ultimate analysis was used to determine the lower calorific value of the biomass materials. The study used a Rankine cycle and applied the First Law of Thermodynamics. Biomass can replace natural gas in the EAF steelmaking process.

Procceedings of the 19th Brazilian Congress of Thermal Sciences and Engineering, 2022

This paper presents the electricity and hydrogen co-production concept, a methodology for the stu... more This paper presents the electricity and hydrogen co-production concept, a methodology for the study of SOFC hydrogen co-production, and simulation results that address the impact of reformer placement in the cycle on system performance. The methodology is based on detailed thermodynamic and electrochemical analyses of the systems. A comparison is made between six specific cycle configurations, which use fuel cell heat to drive hydrogen production in a reformer using both external and internal reforming options. SOFC plant performance has been evaluated on the basis of methane fuel utilization efficiency and each component of the plant has been evaluated on the basis of second law efficiency. The analyses show that in all cases the exergy losses (irreversibilities) in the combustion chamber are the most significant losses in the cycle. Furthermore, for the same power output, the internal reformation option has the higher electrical efficiency and produces more hydrogen per unit of natural gas supplied. Electrical efficiency of the proposed cycles ranges from 41 to 44%, while overall efficiency (based on combined electricity and hydrogen products) ranges from 45 to 80%. The internal reforming case (steam-to-carbon ratio of 3.0) had the highest overall and electrical efficiency (80 and 45% respectively), but lower second law efficiency (61%), indicating potential for cycle improvements.

Social Science Research Network, 2022