Investigation of the operating conditions on the water and thermal management for a polymer electrolyte membrane fuel cell by one-dimensional model 2020-01-0856
Water and thermal management is an essential issue that influences performance and durability of a polymer electrolyte membrane fuel cell (PEMFC). Water content in membrane decides its ionic conductivity and membrane swelling favors the ionic conductivity, resulting in decreases in the membrane’s ohmic resistance and improvement in the output voltage. However, if excessive liquid water can’t be removed out of cell quickly, it will fill in the pores of catalyst layer (CL) and gas diffusion layer (GDL) then flooding may occur. It is essential to keep the water content in membrane at a proper level. In this work, a transient isothermal one-dimensional model is developed to investigate effects of the relative humidity of inlet gas and cell temperature on performance of a PEMFC. Comprehensive physical and chemical phenomenon inside the cell is included, especially the mass transfer of hydrogen, oxygen, vapor and liquid water in gas channels, GDL and CL and non-frozen membrane water in ionomer. Phase change between vapor and liquid water is also considered. The cell’s performances at the conditions of the different relative humidity of inlet gas and the different cell temperatures are analyzed. The results show that it has the lowest mass transfer loss and acceptable ohmic loss at the condition that relative humidity of the vapor in CL is close to its saturated value. The most suitable temperature of a cell increases with improving the current density when relative humidity of inlet gas remains unchanged. The optimum temperature goes up with increasing relative humidity of the inlet gas when current density keeps unchanged.