As we all know, PEMFC (proton exchange membrane or polymer electrolyte membrane fuel cell) is a potential candidate for the future power sources of automobile applications. Developing analytical or numerical model is a very popular method to optimize water and thermal management of PEMFC beyond conducting experiments. Among these various models, the 3D (three-dimensional) multi-scale CFD (computational fluid dynamics) model developed based on the real geometry structure takes the advantages of high accuracy because it is able to take almost all the transport phenomena and electrochemical reactions into consideration. Utilizing the 3D multi-phase CFD model, the large-scale PEMFC (about 110 cm2) is simulated to investigate the influence of operating conditions in this study. More specifically, the effects of operating pressure (1.0-4.0 atm) on PEMFC performance and internal water and thermal management under different inlet humidity (1.0 and 0.4) are studied in detail. It is found that the PEMFC performance increases with the increment of operating pressure thanks to the increased gas species concentration. Meanwhile, the pressure drop in PEMFC is decreased at high operating pressure because of the high inlet gas density, which is likely to reduce the demand of flow field design in reducing pressure drop. But it should be noted that high operation pressure also results in increasing pumping power loss, thereby high operating pressure does not necessarily mean high net power density. Additionally, the increased water vapor concentration is also helpful to improve the membrane water absorption level, which reduces the Ohmic loss of PEMFC, especially at low inlet humidity.
Guobin Zhang, Xu Xie, Jin Xuan, Kui Jiao, Yun Wang
Tianjin Univ., Loughborough university, University of California, Irvine