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Effects of Stack Array Orientation on Fuel Cell Efficiency for Auxiliary Power Unit Applications

UCD-ITS-RP-10-55

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Suggested Citation:
Choi, Kap-Seung, S.-H. Jang, G. S. Shin, Hyung-Man Kim, Hyung-Chul Yoon, Matthew E. Forrest, Paul A. Erickson (2010) Effects of Stack Array Orientation on Fuel Cell Efficiency for Auxiliary Power Unit Applications. International Journal of Automotive Technology 11 (3), 429 - 434

The commercial fuel cell products currently appearing on the market are self-contained fuel cell engines. These engines can be used for many applications that are presently dominated by internal combustion engines or batteries. Vehicle mounted fuel cell auxiliary power units have been attracting attention lately. Additionally, there is a market based incentive to use multiple small fuel cell arrays in place of a single large fuel cell for some applications. Typically, fuel cells are designed to operate as stand-alone units. This paper investigates the ability of small commercial stacks to operate in common array arrangements. Although an individual Nexa is able to produce 1500 W, Dual Nexas do not maintain that capability while in array configurations. With an overall load share ratio of 1.02:1 the series array reliably produced 2900 W of power, while with an overall load share ratio of 1.09:1 the parallel array reliably produced only 2800 W of power. This study shows that array orientation affects both system stack net efficiency and individual stack net efficiency. The information gained from this study may be helpful for fuel cell design and integration.

Keywords: fuel cell auxiliary power unit, fuel cell array, Nexa power module, array orientation, stack net efficiency