Trade-Off Design Analysis of Operating Pressure and Temperature in PEM Fuel Cell Systems

1999 ◽  
Author(s):  
Frano Barbir ◽  
Bhaskar Balasubramanian ◽  
Jay Neutzler
Keyword(s):  
Fuel Cell ◽  
Cell Polarization ◽  
Propulsion System ◽  
Automotive Application ◽  
Total Efficiency ◽  
Operating Voltage ◽  
Operating Pressure ◽  
Surprising Result ◽  
Partial Load ◽  
Full Power

Abstract The paper presents the results of an optimization study of an automotive fuel cell propulsion system equipped with a fuel reformer. Based on a set of fuel cell polarization curves determined experimentally by running a prototype fuel cell stack at a variety of operating pressures and temperatures, a numerical steady state model was used to determine the optimal operating pressure and temperature. The optimization criteria were the size of individual components and the entire propulsion system as well as its total efficiency at both full power and partial load. The results suggested that an automotive system should be operated at relatively high pressure (308 kPa), but an expander must be used to recover most of the power used for compression. A surprising result of this analysis is that a relatively low temperature (∼60°C) results in smallest heat rejection equipment if neutral water balance is mandated. The efficiency of the system is about 33% at full power and about 38% at 25% of the load. Higher efficiencies may be achieved by selecting a higher fuel cell operating voltage, but that would result in larger fuel cell stacks, which may be a limiting factor for automotive application with the state-of-the-art fuel cells.

Enhancing the Performance Evaluation and Process Design of a Commercial-Grade Solid Oxide Fuel Cell via Exergy Concepts

2002 ◽  
Vol 124 (2) ◽  
pp. 95-104 ◽  
Author(s):  
Comas Haynes ◽  
William J. Wepfer
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Process Design ◽  
Solid Oxide ◽  
Operating Voltage ◽  
Operating Pressure ◽  
Oxide Fuel ◽  
Exergetic Efficiency ◽  
Fuel Cell Performance ◽  
Efficiency Measures

Fuel cell technology is a promising means of energy conversion. As the technology matures, process design and analysis are gaining importance. The conventional measures of fuel cell performance (i.e., gross real and voltage efficiencies) are limited indices-of- merit. Contemporary second law concepts (availability/exergy, irreversibility, exergetic efficiency) have been used to enhance fuel cell evaluation. A previously modeled solid oxide fuel cell has been analyzed using both conventional measures and the contemporary thermodynamic measures. Various cell irreversibilities were quantified, and their impact on cell inefficiency was better understood. Exergetic efficiency is more comprehensive than the conventional indices-of- performance. This parameter includes thermal irreversibilities, considers the value of effluent exergy, and has a consistent formulation. Usage of exergetic efficiency led to process design discoveries different from the trends observed in conjunction with the conventional efficiency measures. The decision variables analyzed were operating pressure, air stoichiometric number (inverse equivalence ratio), operating voltage and fuel utilization.

Exergy Analysis of a Hybrid Micro Gas Turbine Fuel Cell System Based on Existing Components

2012 ◽  
Author(s):  
D. P. Bakalis ◽  
A. G. Stamatis
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Exergy Analysis ◽  
Cell System ◽  
System Component ◽  
Utilization Factor ◽  
Fuel Cell Stack ◽  
Micro Gas Turbine ◽  
Partial Load ◽  
Set Up

A hybrid system based on an existing recuperated microturbine and a pre-commercially available high temperature tubular solid oxide fuel cell is modeled in order to study its performance. Individual models are developed for the microturbine and fuel cell generator and merged into a single one in order to set up the hybrid system. The model utilizes performance maps for the compressor and turbine components for the part load operation. The full and partial load exergetic performance is studied and the amounts of exergy destruction and efficiency of each hybrid system component are presented, in order to evaluate the irreversibilities and thermodynamic inefficiencies. Moreover, the effects of various performance parameters such as fuel cell stack temperature and fuel utilization factor are investigated. Based on the available results, suggestions are given in order to reduce the overall system irreversibility. Finally, the environmental impact of the hybrid system operation is evaluated.

scholarly journals Wide Operating Voltage Range Fuel Cell Battery Charger

2014 ◽  
Vol 20 (5) ◽  
Author(s):  
J. C. Hernandez ◽  
M. C. Mira ◽  
G. Sen ◽  
O. C. Thomsen ◽  
M. A. E. Andersen
Keyword(s):  
Fuel Cell ◽  
Operating Voltage ◽  
Battery Charger ◽  
Voltage Range ◽  
Wide Operating

Fuel Cell Propulsion System Layout

2021 ◽  
pp. 137-151
Author(s):  
Stephan Schnorpfeil ◽  
Erik Hartmann ◽  
Arne Kotowski ◽  
Bhavin Kapadia ◽  
Hauke Sötje
Keyword(s):  
Fuel Cell ◽  
Propulsion System ◽  
System Layout

PEM Fuel Cell Research Direction for Automotive Application

2005 ◽  
Author(s):  
John Fagley ◽  
Jason Conley ◽  
David Masten
Keyword(s):  
Fuel Cell ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Department Of Energy ◽  
Limiting Current ◽  
Automotive Application ◽  
Commercial Application ◽  
Related Research

In recent years, there has been an increasing amount of PEM (proton exchange membrane) fuel cell-related research conducted and subsequently published by universities and public institutions. While a good deal of this research has been useful for understanding the underlying fundamental aspects of fuel cell components and operation, much of it is not as useful for a group working on automotive applications as it could be. The reason for this is that in order to be put to practical use in an automotive application, the system being studied must meet certain constraints; satisfying targets for projected system costs, system efficiency, volumetric and gravimetric power densities (packaging), and operating conditions. For example, numerous recent publications show studies with PEM fuel cells designed and built such that limiting current density is achieved at 0.9 A/cm2 or lower, and voltages of 600 mV can only be achieved at current densities less than 0.6 A/cm2. This type of performance is sufficiently below what is required for commercial application, that any conclusions drawn from these works are difficult to extrapolate to a system of commercial automotive interest. The purpose of this article is to show, through use of engineering calculations and cost projections, what operating conditions and performance are required in a commercial automotive fuel cell application. In addition, best known (public domain) performance and corresponding conditions are given, along with Department of Energy Freedom Car targets, which can be used for state-of-the-art benchmarking. Also, reference is made to a university publication where performance (500 mV at 1.5 A/cm2) close to automotive application targets was achieved, and important aspects of their components and flow field geometry are highlighted. It is our hope that through this publication, further PEM fuel-cell related research can be directed toward the region of greatest interest for commercial, automotive application.

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