Novel Dynamic Quasi-3-Dimensional High Temperature Fuel Cell Model With Internal Manifolding

2010 ◽  
Author(s):  
Dustin McLarty ◽  
Scott Samuelsen ◽  
Jack Brouwer
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Cell Model ◽  
Single Cells ◽  
Internal Heat ◽  
Transient Temperature ◽  
Inlet Temperature ◽  
Molten Carbonate ◽  
Internal Reforming

High temperature fuel cells have demonstrated potential for a wide array of energy applications while meeting future efficiency and emission targets. Earlier works captured either steady state performance of stacks or transient behavior of single cells. This work develops a model that can simulate and spatially resolve transient temperature, pressure and species distributions for a simulated fuel cell stack in a computationally efficient manner. The novel model accounts for internal manifolding of fuel and oxidant streams and predicts two dimensional fields associated with the dynamic operation of a single high temperature fuel cell. The MatLab-Simulink® model calculates dynamic performance for both solid oxide and molten carbonate fuel cells that utilize both direct and indirect internal reforming. This paper presents dynamic response characteristics to perturbations in power, fuel utilization and composition, and investigates control strategies that minimize PEN temperature variations and fluctuations during the transient responses. Air flow and inlet temperature controls are sufficient to control average PEN temperature, but internal heat transfer dynamics substantially change the spatial temperature distribution dynamics at different operational power densities.

scholarly journals Exploring the Possibility of Using Molten Carbonate Fuel Cell for the Flexible Coproduction of Hydrogen and Power

2021 ◽  
Vol 9 ◽  
Author(s):  
Utkarsh Shikhar ◽  
Kas Hemmes ◽  
Theo Woudstra
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Fuel Utilization ◽  
Molten Carbonate ◽  
Internal Reforming ◽  
Molten Carbonate Fuel Cells

Fuel cells are electrochemical devices that are conventionally used to convert the chemical energy of fuels into electricity while producing heat as a byproduct. High temperature fuel cells such as molten carbonate fuel cells and solid oxide fuel cells produce significant amounts of heat that can be used for internal reforming of fuels such as natural gas to produce gas mixtures which are rich in hydrogen, while also producing electricity. This opens up the possibility of using high temperature fuel cells in systems designed for flexible coproduction of hydrogen and power at very high system efficiency. In a previous study, the flowsheet software Cycle-Tempo has been used to determine the technical feasibility of a solid oxide fuel cell system for flexible coproduction of hydrogen and power by running the system at different fuel utilization factors (between 60 and 95%). Lower utilization factors correspond to higher hydrogen production while at a higher fuel utilization, standard fuel cell operation is achieved. This study uses the same basis to investigate how a system with molten carbonate fuel cells performs in identical conditions also using Cycle-Tempo. A comparison is made with the results from the solid oxide fuel cell study.

Parametric Analysis and Optimization of a High Temperature Fuel Cell: Supercritical CO2 Turbine Hybrid System

2008 ◽  
Author(s):  
D. Sa´nchez ◽  
R. Chacartegui ◽  
A. Mun˜oz ◽  
T. Sa´nchez
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Operating Temperature ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Molten Carbonate ◽  
Turbine Inlet Temperature

The integration of high temperature fuel cells — molten carbonate and solid oxide — and gas turbine engines for efficient power generation is not new. Different strategies for integrating both systems have been proposed in the past ten years and there are some field tests being run presently. However, the commercial availability of such power systems seems to be continuously delayed, probably due to cost and reliability problems. The materials used in high temperature fuel cells are expensive and their cost is not decreasing at the expected pace. In fact, it looks as if they had reached stabilization. Therefore, there seems to be agreement that operating at a lower temperature might be the only way to achieve more competitive costs to enter the market, as metallic materials could then be used. From the point of view of conventional hybrid systems, decreasing the operating temperature of the cell would affect the efficiency of the bottoming cycle dramatically, as long as turbine inlet temperature is a critical parameter for the performance of a Brayton cycle. This is the reason why hybrid systems perform better with solid oxide fuel cells operating at 1000 °C than with molten carbonate cells at 650 °C typically. This work presents a hybrid system comprising a high temperature fuel cell, either SOFC or MCFC, and a bottoming Brayton cycle working with supercritical carbon dioxide. A parametric analysis is done where all the parameters affecting the performance of the hybrid system are studied, with emphasis in the bottoming cycle. For the Brayton cycle: pressure ratio, expansion and compression efficiencies, recuperator effectiveness, pressure losses, turbine inlet temperature... For the fuel cell: fuel utilization, current density, operating temperature, etc. From this analysis, optimum operating point and integration scheme are established and, after this, a comparison with conventional hybrid systems using similar fuel cells is done. Results show that, although the fuel cell is not pressurized in the CO2 based system, its performance is similar to the best conventional cycle. Furthermore, if lower operating temperatures are considered for the fuel cell, the new system performs better than any of the conventional.

Numerical Simulation of the Molten Carbonate Fuel Cell Performance Under Different Operational Conditions

2003 ◽  
Author(s):  
Zhiwen Ma ◽  
S. M. Jeter ◽  
S. I. Abdel-Khalik
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Flow Rate ◽  
Gas Flow ◽  
Cell Performance ◽  
Molten Carbonate ◽  
Gas Flow Rate ◽  
Cell Temperature ◽  
Internal Reforming

Thermal management of high temperature fuel cells is critical to fuel cell operation and reliability. Locally extreme cell temperature may cause high thermal stress and accelerated corrosion process, which could shorten the cell life and induce local electric and thermal contact loss. Fuel cell temperature usually is controlled by the gas flow stream cooling, or the internal reforming if the internal reforming process is incorporated inside the high temperature fuel cells. This paper discusses the gas flow rate effect on a single cell performance based on mathematical model. The parameter distribution and cell performance versus the gas flow rate are presented.

Power Cycle Integration and Efficiency Increase of Molten Carbonate Fuel Cell Systems

2005 ◽  
Vol 3 (4) ◽  
pp. 375-383 ◽  
Author(s):  
Petar Varbanov ◽  
Jiří Klemeš ◽  
Ramesh K. Shah ◽  
Harmanjeet Shihn
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Gas Turbines ◽  
Waste Heat ◽  
Combined Cycle ◽  
Molten Carbonate Fuel Cell ◽  
Steam Turbines ◽  
Molten Carbonate ◽  
Carbonate Fuel Cell

A new view is presented on the concept of the combined cycle for power generation. Traditionally, the term “combined cycle” is associated with using a gas turbine in combination with steam turbines to better utilize the exergy potential of the burnt fuel. This concept can be broadened, however, to the utilization of any power-generating facility in combination with steam turbines, as long as this facility also provides a high-temperature waste heat. Such facilities are high temperature fuel cells. Fuel cells are especially advantageous for combined cycle applications since they feature a remarkably high efficiency—reaching an order of 45–50% and even close to 60%, compared to 30–35% for most gas turbines. The literature sources on combining fuel cells with gas and steam turbines clearly illustrate the potential to achieve high power and co-generation efficiencies. In the presented work, the extension to the concept of combined cycle is considered on the example of a molten carbonate fuel cell (MCFC) working under stationary conditions. An overview of the process for the MCFC is given, followed by the options for heat integration utilizing the waste heat for steam generation. The complete fuel cell combined cycle (FCCC) system is then analyzed to estimate the potential power cost levels that could be achieved. The results demonstrate that a properly designed FCCC system is capable of reaching significantly higher efficiency compared to the standalone fuel cell system. An important observation is that FCCC systems may result in economically competitive power production units, comparable with contemporary fossil power stations.

Thermo-Kinetic Representation and Transient Simulation of a Molten Carbonate Fuel Cell

2005 ◽  
Author(s):  
Brian C. Carroll ◽  
Thomas M. Kiehne ◽  
Michael D. Lukas
Keyword(s):  
Fuel Cell ◽  
Cell Model ◽  
Operating Conditions ◽  
Molten Carbonate Fuel Cell ◽  
System Level ◽  
Transient Temperature ◽  
Molten Carbonate ◽  
Fuel Cell Performance ◽  
Fuel Reformation ◽  
Carbonate Fuel Cell

There are a growing number of models in the literature dealing with the transient behavior of fuel cells. However, few, if any, employ fundamental kinetic theory to model the fuel reformation process while simultaneously simulating fuel cell behavior from a transient, system-level perspective. Thus a comprehensive, transient fuel cell model has been developed that includes all the relevant thermodynamics, chemistry, and electrical characteristics of actual fuel cell operation. The model tracks the transient temperature response of a fuel cell stack, chemical specie concentrations of exhaust gases, efficiency of the fuel reformation equipment, and electrical output characteristics. Model results provide a concise, parametric evaluation of the influence of operating conditions and user-controlled parameters on fuel cell performance. The model is validated against transient Molten Carbonate fuel cell (MCFC) data from a subscale stack.

Design and Experimental Characterization of a High-Temperature Proton Exchange Membrane Fuel Cell Stack

2011 ◽  
Vol 8 (5) ◽  
Author(s):  
Robert Radu ◽  
Nicola Zuliani ◽  
Rodolfo Taccani
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Single Cells ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Pure Hydrogen ◽  
Exchange Membrane

Proton exchange membrane (PEM) fuel cells based on polybenzimidazole (PBI) polymers and phosphoric acid can be operated at temperature between 120 °C and 180 °C. Reactant humidification is not required and CO content up to 1% in the fuel can be tolerated, only marginally affecting performance. This is what makes high-temperature PEM (HTPEM) fuel cells very attractive, as low quality reformed hydrogen can be used and water management problems are avoided. From an experimental point of view, the major research effort up to now was dedicated to the development and study of high-temperature membranes, especially to development of acid-doped PBI type membranes. Some studies were dedicated to the experimental analysis of single cells and only very few to the development and characterization of high-temperature stacks. This work aims to provide more experimental data regarding high-temperature fuel cell stacks, operated with hydrogen but also with different types of reformates. The main design features and the performance curves obtained with a three-cell air-cooled stack are presented. The stack was tested on a broad temperature range, between 120 and 180 °C, with pure hydrogen and gas mixtures containing up to 2% of CO, simulating the output of a typical methanol reformer. With pure hydrogen, at 180 °C, the considered stack is able to deliver electrical power of 31 W at 1.8 V. With a mixture containing 2% of carbon monoxide, in the same conditions, the performance drops to 24 W. The tests demonstrated that the performance loss caused by operation with reformates, can be partially compensated by a higher stack temperature.

Operation of Carbonate Fuel Cell (MCFC) Using Syngas

2011 ◽  
Author(s):  
Joseph McInerney ◽  
Hossein Ghezel-Ayagh ◽  
Robert Sanderson ◽  
Jennifer Hunt
Keyword(s):  
Power Generation ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Natural Gas ◽  
High Efficiency ◽  
Cell System ◽  
System Level ◽  
Molten Carbonate ◽  
Fuel Cell Stack ◽  
Internal Reforming

High temperature fuel cells, such as Molten Carbonate Fuel Cells (MCFC), are prime candidates for power generation using natural gas. Currently MCFC-based products are available for on-site power generation using natural gas and methane-rich biogas. These systems use the most advanced stack configuration utilizing internal reforming of methane. The in-situ reforming within the fuel cell anode provides many operational benefits including stack cooling at high current densities. Syngas from a variety of sources such as coal, biomass and renewables are anticipated to play a key role in the future landscape of power generation. MCFC is capable of utilizing syngss to produce electric power at a very high efficiency. However, because of the differences in the gas compositions between natural-gas and syngas, the fuel cell stack and system designs need to be modified for syngas fuels. The purpose of this study is to develop the design modifications at both the stack and system level needed for operation of internal reforming MCFC using low-methane content syngas without major design changes from the commercial product design. The net outcome of the investigation is a fuel cell system which meets the goals of being able to operate on low methane syngas within thermo-mechanical requirements of the fuel cell stack components. In this paper, we will describe the approach for modification of MCFC design and operating parameters for operation under syngas using both system level modeling and stack level mathematical modeling.

Electrochemical Carbon Separation in a SOFC-MCFC Poly-Generation Plant With Near-Zero Emissions

2017 ◽  
Author(s):  
Luca Mastropasqua ◽  
Stefano Campanari ◽  
Jack Brouwer
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Carbon Capture ◽  
Large Scale ◽  
High Efficiency ◽  
Molten Carbonate Fuel Cell ◽  
Small Scale ◽  
Total Efficiency ◽  
Molten Carbonate

High temperature fuel cells have been studied as a suitable solution for Carbon Capture and Storage (CCS) purposes at a large scale (>100 MW). However, their modularity and high efficiency at small-scale make them an interesting solution for Carbon Capture and Utilisation at the distributed generation scale when coupled to appropriate use of CO2 (i.e., for industrial uses, local production of chemicals etc.). These systems could be used within low carbon micro-grids to power small communities in which multiple power generating units of diverse nature supply multiple products such as electricity, cooling, heating and chemicals (i.e., hydrogen and CO2). The present work explores fully electrochemical power systems capable of producing a highly pure CO2 stream and hydrogen. In particular, the proposed system is based upon integrating a Solid Oxide Fuel Cell (SOFC) with a Molten Carbonate Fuel Cell (MCFC). The use of these high temperature fuel cells has already been separately applied in the past for CCS applications. However, their combined use is yet unexplored. Moreover, both industry and US national laboratories have expressed their interest in this solution. The reference configuration proposed envisions the direct supply of the SOFC anode outlet to a burner which, using the cathode depleted air outlet, completes the oxidation of the unconverted species. The outlet of the burner is then fed to the MCFC cathode inlet which separates the CO2 from the stream. Both the SOFC and MCFC anode inlets are supplied with pre-reformed and desulfurized natural gas. The MCFC anode outlet, which is characterised by a high concentration of CO2, is fed to a CO2 separation line in which a two-stage Water Gas Shift (WGS) reactor and a PSA/membrane system respectively convert the remaining CO into H2 and remove the H2 from the exhaust stream. This has the significant advantage of achieving the required CO2 purity for liquefaction and long-range transportation without requiring the need of cryogenic or distillation plants. Moreover, the highly pure H2 stream can either be sold as transportation fuel or a valuable chemical. Furthermore, different configurations are considered with the final aim of increasing the Carbon Capture Ratio (CCR) and maximising the electrical efficiency. Moreover, the optimal power ratio between SOFC and MCFC stacks is also explored. Complete simulation results are presented, discussing the proposed plant mass and energy balances and showing the most attractive configurations from the point of view of total efficiency and CCR.

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