Water and Thermal Balance in PEM and Direct Methanol Fuel Cells

A key consideration for portable power systems is that they must operate simultaneously at water balance (no external water supply) and thermal balance (controlled temperature). Water and thermal management are intimately linked since evaporation is a potent source of cooling. This paper presents the basic design relationships that govern water and thermal balance in polymer electrolyte membrane (PEM) fuel cell stacks and systems. Hydrogen/air and direct methanol fuel cells are both addressed and compared. Operating conditions for simultaneous water and thermal balance can be specified based on the cell’s electrochemical performance and the operating environment. These conditions can be used to specify the overall size and complexity of the cooling equipment. The water balance properties can have strong effects on the size of the thermal management equipment required.

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Water Balance in PEM and Direct Methanol Fuel Cells

Journal of Fuel Cell Science and Technology ◽

10.1115/1.1840758 ◽

2004 ◽

Vol 2 (1) ◽

pp. 1-8 ◽

Cited By ~ 5

Author(s):

Michael G. Izenson ◽

Roger W. Hill

Keyword(s):

Fuel Cells ◽

Water Balance ◽

Power Systems ◽

Direct Methanol Fuel Cells ◽

Polymer Electrolyte Membrane ◽

Pem Fuel Cells ◽

Electrolyte Membrane ◽

Direct Methanol ◽

Specific Calculations ◽

Methanol Fuel Cells

Water management is a critical design issue for polymer electrolyte membrane (PEM) fuel cells, because the PEM must be maintained at the proper water content to remain ionically conducting without flooding the electrodes. Furthermore, portable PEM power systems should operate at water balance to minimize weight. This paper presents the basic design relationships that govern water balance in a PEM fuel cell. Specific calculations are presented based on data from hydrogen/air and direct methanol fuel cells currently under development for portable power systems. We will show how the water balance operating point depends on the cell operating parameters and show the sensitivity to off-design conditions.

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Water and Thermal Balance in PEM Fuel Cells

1st International Fuel Cell Science, Engineering and Technology Conference ◽

10.1115/fuelcell2003-1756 ◽

2003 ◽

Cited By ~ 1

Author(s):

Michael G. Izenson ◽

Roger W. Hill

Keyword(s):

Fuel Cells ◽

Fuel Cell ◽

Water Balance ◽

Electrochemical Performance ◽

Thermal Management ◽

Direct Methanol Fuel Cells ◽

Pem Fuel Cell ◽

Thermal Balance ◽

Operating Conditions ◽

Portable Power

The high energy density available from polymer electrolyte membrane (PEM) fuel cell systems makes them attractive sources of portable power. A key consideration for minimum weight portable power systems is that they must operate simultaneously at water balance (no external water supply) and thermal balance (controlled temperature). Water and thermal management are intimately linked since evaporation is a potent source of cooling. The cell’s electrochemical performance and the ambient environment determine the rates of water production and transport as well as heat generation and removal. This paper presents the basic design relationships that govern water and thermal balance in PEM fuel cell stacks and systems. Hydrogen/air and direct methanol fuel cells are both addressed and compared. Operating conditions for simultaneous water and thermal balance can be specified based on the cell’s electrochemical performance and the operating environment. These conditions can be used to specify the overall size and complexity of the cooling equipment needed in terms of the “UA” product of the heat exchangers. The water balance properties can have strong effects on the size of the thermal management equipment required.

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