Effect of Flow Field Structure and Operating Condition on the Distributions of Water and Phosphoric Acid in High Temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC)

Abstract

Since distributions of water and phosphoric acid (PA) have significant influence on the performance of high temperature proton exchange membrane fuel cell (HT-PEMFC) and are difficult to be characterized by experiment, a nonisothermal multiphase model considering the effect of PA polycondensation on the proton conductivity is developed to investigate the influence of flow field structures and operating conditions on these distributions for a HT-PEMFC with area of 160 cm2. The results show that the flow field has little effect on discharge performance when pure hydrogen is feed. With the increase of anode stoichiometry, the PA concentration is elevated, which resulted in a lower proton conductivity. When current density increases from 200 to 600 mA cm–2, PA concentration (average value of MEA) decreases from 97.26 to 94.82 wt %. Although a higher temperature leads to aggravation of PA polycondensation, the proton conductivity is improved. With the increasing of water vapor composition of the anode feed, the PA is diluted and proton conductivity decreases.