Effect of the cooling water flow direction on the performance of PEMFCs

Abstract

A problematic large temperature difference is observed between the PEMFC inlet and outlet under a traditional unidirectional cooling flow (Model A). We propose three new cooling modes to better distribute heat in a fuel cell: reverse flow cooling of the interlayer flow channel (Model B), reverse flow cooling of the adjacent channel (Model C), and bidirectional circulation cooling (Model D). The different cooling pattern effects on the temperature, and substance concentration distributions along with PEMFC performance were simulated. The commutation time in Model D was also investigated. The results show that Model B demonstrates limited improvement in the PEMFC temperature distribution with temperature difference only reduced by 0.6 K, while Model C and Model D show effective improvement with temperature difference reduced by 4.3 K and 3.2 K, respectively. Furthermore, the power density values of Model C and Model D are increased by 23% and 20.6% when operating at an operating voltage of 0.65 V; when the power density is 0.7 W cm−2, the efficiency of Model C and Model D are improved by 7.8% and 4.7%, respectively, when compared with that of Model A, which illustrates that better temperature distribution uniformity leads to better cell performance and efficiency. With a short commutation time, the highest temperature is distributed in the middle of the PEMFC. With an increase in commutation time, the high-temperature position will gradually shift from the middle to both ends of the PEMFC.