| dc.description.abstract | Except water and power, proton exchange membrane fuel cell (PEMFC) also generates heat while it is on operating. In order to keep PEMFC working in low temperature condition (<80 。C), it is required to develop a cooling system to remove waste heat. This study is focused on air cooling method, because it has the advantage of avoiding ionic contamination problem in liquid cooling method. Moreover, metal foam is lightweight, has high thermal conductivity, and large surface area for heat exchange. This study is the first investigation on metal foam applied to PEMFC cooling system.
In this study, the cooling ability of the plate designs in metal foam cooling channel and traditional cooling channels, including column channel and serpentine channel, are compared. Via measuring heat transfer coefficient, the correlation between Nu and Re is established empirically. These cooling designs are also applied to a 4-cell stack to verify the cooling effect.
The results show that the cooling ability of traditional cooling design is relatively poor due to the non-uniformity of gas flow, and the surface area for heat exchange is difficult to be increased in the traditional cooling design. On the contrary, the metal foam cooling design is better than the traditional ones. With the larger effective surface area and the ability to force a uniform gas flow, the heat transfer coefficient on metal foam design is larger than that of the traditional design, and it leads to that more heat could be taken away by the metal foam cooling design in a limited heating area. The pressure drop is larger in the metal foam design due to the drag caused by the porous structure, thus it needs extra pump work. However, the overall efficiency is still higher on system using metal foam cooling design than using traditional design. Thus it is recommended using metal foam design in a PEMFC stack system.
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