Experimental and numerical studies of mode switching performance and water transfer in unitized regenerative fuel cells with different channel structures

Abstract

Different flow channel structures of unitized regenerative fuel cells have great effects on the flow process of reactive gas, liquid product and flowing purge gas inside channels and the transport process of them in the porous media layer. In this study, the unitized regenerative fuel cell with three different kinds of channel structures are designed and manufactured based on the numerical simulation. By utilizing the unitized regenerative fuel cell testing set-up, the output electricity performance test of the single cell in the fuel cell mode, electrolytic cell mode and mode switching process are realized, and effective verification data are provided for the two-phase model verification of unitized regenerative fuel cells. The results show that different channel configurations result in various performance behaviors during different procedures of the cell. Using the channel having 1 mm square cross-section structures can perform better start-up performance, compared to the T-wide and T-narrow section channels. When entering into electrolysis cell mode, compared to the cell with T-section channels, the output performance of the cell constructed with 1 mm square section channel is decreased obviously at the initial stage of start-up because of the residual water affecting. The present experiments combined with simulation works facilitate better understanding how the performance and two-phase species changing at the operating procedures of unitized regenerative fuel cells with different flow channels.