Metal foam heat exchangers for thermal management of fuel cell systems – An experimental study

The present study explores the possibility of using metal foams for thermal management of fuel cells so that air-cooled fuel cell stacks can be commercialized as replacements for currently-available watercooled counterparts. Experimental studies have been conducted to examine the heat transfer enhancement from a thin metal foam layer sandwiched between two bipolar plates of a cell. To do this, effects of the key parameters including the free stream velocity and characteristics of metal foam such as porosity, permeability, and form drag coefficient on temperature distribution, heat and fluid flow are investigated. The improvements as a result of the application of metal foam layers on fuel cell systems efficiency have been analyzed and discussed. Empirical results were in an agreement with previous numerical studies and have shown that to remove the same amount of generated heat, the air-cooled fuel cell systems using aluminum foams require half of the pumping power compared to water-cooled fuel cell systems. The critical coolant temperature difference for Proton Exchange Membrane (PEM) fuel cell systems was considered in which the applied foam layer created a uniform temperature distribution across the graphite plates.