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SPECIAL SECTION ON THE 2ND EUROPEAN FUEL CELL TECHNOLOGY AND APPLICATIONS CONFERENCE

Basic Electrochemical Thermodynamic Studies of Fuel Cells Using MALT2

[+] Author and Article Information
M. Williams

University of Utah, Salt Lake City, UT 84112

T. Horita, K. Yamagi, N. Sakai, H. Yokokawa

National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan

J. Fuel Cell Sci. Technol 6(2), 021301 (Feb 26, 2009) (6 pages) doi:10.1115/1.3080545 History: Received November 15, 2007; Revised December 07, 2007; Published February 26, 2009

Abstract

There are at least four basic fuel cell thermodynamic features: maximum intrinsic thermal efficiency (electrical efficiency), reversible potential, and two new ones—intrinsic cooling requirement and intrinsic exergetic efficiency. A basic electrochemical thermodynamic analysis of fuel cells using MALT reveals that it is probably for thermodynamic reasons that cooling strategies other than excess oxidant, such as water cooling, have generally been adopted for lower temperature fuel cells such as polymer electrolyte fuel cell (PEFC) and phosphoric acid fuel cell (PAFC). One can mathematically demonstrate that for a simple hybrid system, any fuel cell, any operating temperature, and any pressure, the maximum reversible work is equal to the free energy of reaction at the standard state. This study gives information of new opportunity fuels having increasing importance is all future energy scenarios. The results of this analysis show that ammonia and direct methanol give greater maximum intrinsic thermal efficiency than hydrogen oxidation. From these simple studies alone, one would conclude that the great payoff in terms of theoretical efficiency potential for research is direct carbon fuel cell (DCFT), PEFC, and direct oxidation of methane, intermediate temperature solid oxide fuel cell (SOFC), and simple fuel cell turbine hybrids.

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Figures

Figure 1

Maximum intrinsic thermal efficiency

Figure 2

Maximum intrinsic thermal efficiency for various fuels

Figure 3

Maximum intrinsic thermal efficiency for combined reactions for various fuels

Figure 4

Thermal reversible OCV

Figure 5

Minimum intrinsic cooling

Figure 6

Minimum intrinsic cooling

Figure 7

Maximum intrinsic efficiency

Figure 8

Exergetic efficiency map

Figure 9

Thermal efficiency on methane

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