Modeling of a Methane Fuelled Direct Carbon Fuel Cell System

2005 ◽  
Author(s):  
N. Woudstra ◽  
T. P. van der Stelt ◽  
K. Hemmes
Keyword(s):  
Heat Transfer ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Energy Conversion ◽  
Fuel Conversion ◽  
Cell Systems ◽  
Electrochemical Conversion ◽  
Direct Carbon Fuel Cell ◽  
Conversion Efficiencies

Energy conversion today is subject to high thermodynamic losses. About 50 to 90 % of the exergy of primary fuels is lost during conversion into power or heat. The fast increasing world energy demand makes a further increase of conversion efficiencies inevitable. The substantial thermodynamic losses (exergy losses of 20 to 30 %) of thermal fuel conversion will limit future improvements of power plant efficiencies. Electrochemical conversion of fuel enables fuel conversion with minimum losses. Various fuel cell systems have been investigated at the Delft University of Technology during the past twenty years. It appeared that exergy analyses can be very helpful in understanding the extent and causes of thermodynamic losses in fuel cell systems. More than 50 % of the losses in high temperature fuel cell (MCFC and SOFC) systems can be caused by heat transfer. Therefore system optimisation must focus on reducing the need for heat transfer as well as improving the conditions for the unavoidable heat transfer. Various options for reducing the need for heat transfer are discussed in this paper. High temperature fuel cells, eventually integrated into gas turbine processes, can replace the combustion process in future power plants. High temperature fuel cells will be necessary to obtain conversion efficiencies up to 80 % in case of large scale electricity production in the future. The introduction of fuel cells is considered to be a first step in the integration of electrochemical conversion in future energy conversion systems.

The Thermodynamic Evaluation and Optimization of Fuel Cell Systems

2006 ◽  
Vol 3 (2) ◽  
pp. 155-164 ◽  
Author(s):  
N. Woudstra ◽  
T. P. van der Stelt ◽  
K. Hemmes
Keyword(s):  
Heat Transfer ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Energy Conversion ◽  
System Optimization ◽  
Fuel Conversion ◽  
Cell Systems ◽  
Electrochemical Conversion ◽  
Conversion Efficiencies

Energy conversion today is subject to high thermodynamic losses. About 50% to 90% of the exergy of primary fuels is lost during conversion into power or heat. The fast increasing world energy demand makes a further increase of conversion efficiencies inevitable. The substantial thermodynamic losses (exergy losses of 20% to 30%) of thermal fuel conversion will limit future improvements of power plant efficiencies. Electrochemical conversion of fuel enables fuel conversion with minimum losses. Various fuel cell systems have been investigated at the Delft University of Technology during the past 20 years. It appeared that exergy analyses can be very helpful in understanding the extent and causes of thermodynamic losses in fuel cell systems. More than 50% of the losses in high temperature fuel cell (molten carbonate fuel cell and solid oxide fuel cell) systems can be caused by heat transfer. Therefore system optimization must focus on reducing the need for heat transfer as well as improving the conditions for the unavoidable heat transfer. Various options for reducing the need for heat transfer are discussed in this paper. High temperature fuel cells, eventually integrated into gas turbine processes, can replace the combustion process in future power plants. High temperature fuel cells will be necessary to obtain conversion efficiencies up to 80% in the case of large scale electricity production in the future. The introduction of fuel cells is considered to be a first step in the integration of electrochemical conversion in future energy conversion systems.

Assessment of the Potential of Combined Micro Gas Turbine and High Temperature Fuel Cell Systems

2002 ◽  
Author(s):  
Dieter Bohn ◽  
Nathalie Po¨ppe ◽  
Joachim Lepers
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Advanced Materials ◽  
Cell Systems ◽  
Micro Gas Turbine ◽  
Technological Assessment

The present paper reports a detailed technological assessment of two concepts of integrated micro gas turbine and high temperature (SOFC) fuel cell systems. The first concept is the coupling of micro gas turbines and fuel cells with heat exchangers, maximising availability of each component by the option for easy stand-alone operation. The second concept considers a direct coupling of both components and a pressurised operation of the fuel cell, yielding additional efficiency augmentation. Based on state-of-the-art technology of micro gas turbines and solid oxide fuel cells, the paper analyses effects of advanced cycle parameters based on future material improvements on the performance of 300–400 kW combined micro gas turbine and fuel cell power plants. Results show a major potential for future increase of net efficiencies of such power plants utilising advanced materials yet to be developed. For small sized plants under consideration, potential net efficiencies around 70% were determined. This implies possible power-to-heat-ratios around 9.1 being a basis for efficient utilisation of this technology in decentralised CHP applications.

Coupled Concentrating Optics, Heat Transfer, and Thermochemical Modeling of a 100-kWth High-Temperature Solar Reactor for the Thermal Dissociation of ZnO

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
W. Villasmil ◽  
T. Cooper ◽  
E. Koepf ◽  
A. Meier ◽  
A. Steinfeld
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Energy Conversion ◽  
Solar Flux ◽  
Solar Furnace ◽  
Solar Irradiation ◽  
Radiation Boundary Condition ◽  
Solar Reactor ◽  
Concentrated Solar Energy ◽  
Conversion Efficiencies

This work reports a numerical investigation of the transient operation of a 100-kWth solar reactor for performing the high-temperature step of the Zn/ZnO thermochemical cycle. This two-step redox cycle comprises (1) the endothermal dissociation of ZnO to Zn and O2 above 2000 K using concentrated solar energy, and (2) the subsequent oxidation of Zn with H2O/CO2 to produce H2/CO. The performance of the 100-kWth solar reactor is investigated using a dynamic numerical model consisting of two coupled submodels. The first is a Monte Carlo (MC) ray-tracing model applied to compute the spatial distribution maps of incident solar flux absorbed on the reactor surfaces when subjected to concentrated solar irradiation delivered by the PROMES-CNRS MegaWatt Solar Furnace (MWSF). The second is a heat transfer and thermochemical model that uses the computed maps of absorbed solar flux as radiation boundary condition to simulate the coupled processes of chemical reaction and heat transfer by radiation, convection, and conduction. Experimental validation of the solar reactor model is accomplished by comparing solar radiative power input, temperatures, and ZnO dissociation rates with measured data acquired with the 100-kWth solar reactor at the MWSF. Experimentally obtained solar-to-chemical energy conversion efficiencies are reported and the various energy flows are quantified. The model shows the prominent influence of reaction kinetics on the attainable energy conversion efficiencies, revealing the potential of achieving ηsolar-to-chemical = 16% provided the mass transport limitations on the ZnO reaction interface were overcome.

scholarly journals Review of Latest Developments in PEM Fuel Cell Research with Application to Hydrogen Powered Drones

2021 ◽  
Vol 19 ◽  
pp. 7-11
Author(s):  
B. Day ◽  
A. Pourmovahed ◽  
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Low Temperature ◽  
Energy Content ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Cell Systems ◽  
Cell Technology ◽  
Current State

Fuel cells are becoming an increasingly more enticing option to power drones for extended use applications. This is because under certain conditions, fuel cell systems are able to more efficiently store fuel and, therefore, energy compared to standard battery options. This reality has been proven through multiple research efforts and is reviewed in this paper. It is necessary to review the current state of PEM fuel cell technology for drone applications to determine the extent of its limitations and feasibility. For this reason, the latest developments in low temperature and high temperature PEM fuel cells were studied including their limitations and sensitivity to contamination with a focus on drone applications. It has been reported that hydrogen powered fuel cell systems are more efficient than conventional battery applications when the energy content is higher than 4 MJ. A hybrid fuel cell and battery powertrain is preferred for the purpose of counterbalancing the deficiencies of both individual cases. Currently available products were explored, and it was found that there are fuel cell systems available that are capable of powering drones in excess of 23 kg (50 lb).

A Model for Simulation Heat Transfer in Porous Media

2002 ◽  
Author(s):  
Alton J. Reich ◽  
Mahesh M. Athavale
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Fuel Cells ◽  
Steady State ◽  
High Temperature ◽  
Fuel Cell ◽  
Research And Development ◽  
Software Package ◽  
Low Cost ◽  
Fuel Cell Application

The simulation of flow with heat transfer is important in several areas of current research and development interest. These areas include fuel cells and low cost, high temperature seals. This paper describes the implementation of a model for simulating the heat transfer porous media that has been incorporated into the commercial CFD-ACE+ software package. This model has been validated for both steady state and transient cases. Also presented are results for a “typical” fuel cell application.

Development of a Flexible Pilot High Temperature MEA Manufacturing Line

2004 ◽  
Author(s):  
Raymond H. Puffer ◽  
Glen H. Hoppes
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Value Added ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Membrane Material ◽  
Cell Systems ◽  
Manufacturing Line

Despite the fact that the invention of the fuel cell is more than 160 years old, the fuel cell industry today is still in its infancy. While there are many large companies active in the industry, it is, for the most part, dominated by many small and startup companies focused on the design and development of fuel cell systems. Relatively little attention has been given to the cost effective high-volume (i.e., automated) manufacture of the resulting systems and components. If the wide spread commercial use of fuel cells is to become a reality, and we are to realize the potential benefits to our environment and mankind it is essential that we also put the appropriate level of attention on the enabling manufacturing technologies. Celanese Ventures GmbH is a “new venture” arm of Celanese AG, located in Frankfurt, Germany. They are focused on developing the market for their high temperature polybenzimidazole (PBI®)-based membrane material for use in Proton Exchange Membrane (PEM) fuel cells. Several years ago Celanese realized that the best way to ensure the market for their membrane material is to develop the capability to produce complete membrane electrode assemblies (MEAs) that can be incorporated into fuel cell systems being developed by other companies. Furthermore, such value-added processing can be economically advantageous. This paper will describe the multi-phased collaboration between Celanese, the Flexible Manufacturing Center (FMC) located at Rensselaer Polytechnic Institute (RPI), and Progressive Machine and Design (PMD) to develop a fully automated high temperature MEA pilot manufacturing line that began operation in September, 2002. The FMC has and continues to serve in a unique role for a university research center. The FMC has been involved in the concept development, laboratory proof of principle, acquisition management, technical representation during the design, build and implementation phases, and the ongoing optimization of and improvements to the operational pilot line. We will describe the unique properties of the high temperature PBI® membrane and the benefits of this form of membrane in PEM fuel cell operations. The specific role of the FMC during each phase of the project will be highlighted, and a description of the resulting pilot line will be provided. Finally, we will discuss the important role that effective technology transfer plays in a project with the magnitude and complexity described herein.

scholarly journals Review of Latest Developments in PEM Fuel Cell Research with Application to Hydrogen Powered Drones

2021 ◽  
Vol 19 ◽  
pp. 7-11
Author(s):  
B. Day ◽  
A. Pourmovahed ◽  
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Low Temperature ◽  
Energy Content ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Cell Systems ◽  
Cell Technology ◽  
Current State

Fuel cells are becoming an increasingly more enticing option to power drones for extended use applications. This is because under certain conditions, fuel cell systems are able to more efficiently store fuel and, therefore, energy compared to standard battery options. This reality has been proven through multiple research efforts and is reviewed in this paper. It is necessary to review the current state of PEM fuel cell technology for drone applications to determine the extent of its limitations and feasibility. For this reason, the latest developments in low temperature and high temperature PEM fuel cells were studied including their limitations and sensitivity to contamination with a focus on drone applications. It has been reported that hydrogen powered fuel cell systems are more efficient than conventional battery applications when the energy content is higher than 4 MJ. A hybrid fuel cell and battery powertrain is preferred for the purpose of counterbalancing the deficiencies of both individual cases. Currently available products were explored, and it was found that there are fuel cell systems available that are capable of powering drones in excess of 23 kg (50 lb).

Hybrid Gas Turbine and Fuel Cell Systems in Perspective Review

1999 ◽  
Author(s):  
David J. White
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Gas Turbines ◽  
Energy Output ◽  
Net Energy ◽  
Cell Systems

The concept of hybrids combining fuel cell and gas turbine systems is without question neoteric, and probably is less than eight years old. However, this concept is in a sense a logical development derived from the many early systems that embodied the key features of rotating machinery to compress air. It was the introduction of high temperature fuel cells such as the solid oxide fuel cell (SOFC) that allowed the concept of hybrid gas turbine fuel cell systems to take root. The SOFC with an operating temperature circa 1000° C matched well with small industrial gas turbines that had firing temperatures on the same order. The recognition that the SOFC could be substituted for the gas turbine combustor was the first step into the realm of fuel cell topping systems. Fuel cells in general were recognized as having higher efficiencies at elevated pressures. Thus the hybrid topping system where the gas turbine pressurized the fuel cell and the fuel cell supplied the hot gases for expansion over the turbine promised to provide a high level of synergy between the two systems. Bottoming systems using the exhaust of a gas turbine as the working fluid of a fuel cell such as the molten carbonate fuel cell (MCFC) have been identified and are potential future power generation hybrid systems. The MCFC is especially well suited to the bottoming role because of the need to have carbon dioxide present in the inlet air stream. The carbon dioxide in the gas turbine exhaust allows the high temperature blower, normally used to recirculate and inject exhaust products into the inlet air, to be eliminated. Hybrid systems have the potential of achieving fossil fuel to electricity conversion efficiencies on the order of 70% and higher. The costs of hybrid systems in dollars per kilowatt are generally higher than say an advanced gas turbine that is available today but not by much. The net energy output over the life of a hybrid topping system is similar to that of a recuperated gas turbine but possibly lower than a high-efficiency simple-cycle machine, depending on the efficiency of the hybrid. Methodologies to aid in the selection of the hybrid system for future development have to be developed and used consistently. Life cycle analyses (LFA) provide a framework for such selection processes. In particular the concept of net energy output provides a mechanism to assign relative worth to competing concepts.

Near-Zero CO2 Emissions Power Plant Based on High Temperature Fuel Cells

2019 ◽  
Author(s):  
Roberto Carapellucci ◽  
Roberto Cipollone ◽  
Davide Di Battista
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Power Plant ◽  
Energy Conversion ◽  
Gas Turbine ◽  
Co2 Emissions ◽  
Cathode Side ◽  
Energy Conversion Systems

Abstract The recent awareness on the environmental issues related to global warming is leading to the search for always more efficient energy conversion systems and, mainly, with very low carbon dioxide emissions. In fact, they are strictly related to the combustion reaction of fossil fuels which is the main process of the actual power generation technology. In this regard, fuel cells are energy conversion systems which are characterized by higher efficiency and near-zero CO2 emissions. Their novel integration with conventional power plants participates to the concept of the decarbonization of the economy. In this work, the integration of two high temperature fuel cells (HTFC) with a gas turbine power plant has been proposed and investigated, thanks to the combination of a physical model of the fuel cells and a numerical one of the components involved in the gas turbine cycle. In the layout studied, fresh air is compressed, pre-heated and used in a Solid Oxide Fuel Cell (SOFC), where the high operating temperature and the exothermic process give exhaust gases at very high temperatures, suitable for an expansion in a turbine. After the expansion, the gases are rich of CO2 and, so, they can be sent to the cathode side of a Molten Carbonate Fuel Cell (MCFC). Hence, the so-defined integrated plant is composed by three power units: a turbine, a SOFC and a MCFC; operating pressure, fuel need, oxygen and carbon dioxide utilizations in the fuel cells are parameterized in order to optimize the whole plant and find additional room of energy exploitation. Moreover, the MCFC acts as an active device for carbon separation, introducing further environmental benefits.

Gas Turbine Cycles With Solid Oxide Fuel Cells—Part II: A Detailed Study of a Gas Turbine Cycle With an Integrated Internal Reforming Solid Oxide Fuel Cell

1994 ◽  
Vol 116 (4) ◽  
pp. 312-318 ◽  
Author(s):  
S. P. Harvey ◽  
H. J. Richter
Keyword(s):  
Power Generation ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Solid Oxide Fuel Cell ◽  
Energy Conversion ◽  
Gas Turbine ◽  
Solid Oxide ◽  
Oxide Fuel

In conventional energy conversion processes, the fuel combustion is usually highly irreversible, and is thus responsible for the low overall efficiency of the power generation process. The energy conversion efficiency can be improved if immediate contact of air and fuel is prevented. One means to prevent this immediate contact is the use of fuel cell technology. Significant research is currently being undertaken to develop fuel cells for large-scale power production. High-temperature solid oxide fuel cells (SOFC) have many features that make them attractive for utility and industrial applications. However, in view of their high operating temperatures and the incomplete nature of the fuel oxidation process, such fuel cells must be combined with conventional power generation technology to develop power plant configurations that are both functional and efficient. Most fuel cell cycles proposed in the literature use a high-temperature fuel cell running at ambient pressure and a steam bottoming cycle to recover the waste heat generated by the fuel cell. With such cycles, the inherent flexibility and shorter start-up time characteristics of the fuel cell are lost. In Part I of this paper (Harvey and Richter, 1994), a pressurized cycle using a solid oxide fuel cell and an integrated gas turbine bottoming cycle was presented. The cycle is simpler than most cycles with steam bottoming cycles and more suited to flexible power generation. In this paper, we will discuss this cycle in more detail, with an in-depth discussion of all cycle component characteristics and losses. In particular, we will make use of the fuel cell’s internal fuel reforming capability. The optimal cycle parameters were obtained based on calculations performed using Aspen Technology’s ASPEN PLUS process simulation software and a fuel cell simulator developed by Argonne National Laboratory (Ahmed et al., 1991). The efficiency of the proposed cycle is 68.1 percent. A preliminary economic assessment of the cycle shows that it should compare favorably with a state-of-the-art combined cycle plant on a cost per MWe basis.

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