Performance studies of a membrane-based water and heat exchanger using serpentine flow channels for polymer electrolyte membrane fuel cell application

Abstract

This study proposes a serpentine flow field to enhance the performance of a membrane-based water and heat exchanger (MWHE) to employ in polymer electrolyte membrane fuel cells. Two MWHEs (serpentine and parallel-flow channels) are numerically simulated and compared in terms of water vapor transmission rate (WVTR), water recovery ratio (WRR), temperature and dew point at the outlet of the dry side, and the dew point approach temperature (DPAT). For all mass flow rates at the dry and wet inlets, the outlet temperature of the dry side and the dew point at the dry side outlet of the MWHE with serpentine channels are higher compared to the one with parallel channels. Using serpentine channels, compared to simple parallel channels, the WRR is enhanced by 8.5 % to 20 % and the DPAT is diminished by 4 % to 13.6 % for a range of mass flow rates on the wet side. At higher wet-side flow rates, the use of serpentine arrangement has a more significant influence on WRR and DPAT. In both MWHEs, an increase in the dry side mass flow rate leads to a reduction in heat and water transfer rates and an increment in the wet side mass flow rate, resulting in a reduction in the DPAT and WRR. Enhancing the operating pressure has a negative impact on the performance of the MWHE. By changing the operating pressure from 100 to 150 kPa, WRR is reduced by 18.1 % and DPAT is enhanced by 10.2 %.