Abstract
PEMFC (proton exchange membrane or polymer electrolyte membrane fuel cell) is a potential candidate as a future power source for automobile applications. Water and thermal management is important to PEMFC operation. Numerical models, which describe the transport and electrochemical phenomena occurring in PEMFCs, are important to the water and thermal management of fuel cells. 3D (three-dimensional) multi-scale CFD (computational fluid dynamics) models take into account the real geometry structure and thus are capable of predicting real operation/performance. In this study, a 3D multi-phase CFD model is employed to simulate a large-scale PEMFC (109.93 cm2) under various operating conditions. More specifically, the effects of operating pressure (1.0-4.0 atm) on fuel cell performance and internal water and thermal characteristics are studied in detail under two inlet humidities, 100% and 40%. It is found that the PEMFC performance increases with the increment of operating pressure as a result of the increased reactant concentration. Meanwhile, the pressure drop through the PEMFC is decreased under high operating pressure because of the large inlet gas density. Additionally, for low humidity operation, pressurized inlet flows increase the water vapor concentration, which is helpful to improve the membrane hydration and hence reduce the Ohmic loss.