Effects of different heat transfer fluids on thermal distribution and electrochemical performance of PEMFC with a non-isothermal multiphase model

Proton exchange membrane fuel cell (PEMFC) with long service life, low parasitic loss and high-power density is one of the main technologies to achieve zero emission of automobiles. Efficient coolant is crucial for reducing the volume and complexity of thermal management system. In this study, the 3-D non-isothermal multiphase PEMFC model coupled with parallel cooling channels was established by using CFD simulation platform, and then the effects of four heat transfer fluids, namely deionized water, Syltherm800 heat transfer oil, 1.0 vol% Al₂O₃ nanofluid and K_0.78Na_0.22 liquid metal, on the heat and mass transfer characteristics and electrochemical performance of PEMFC were investigated. The results show that with the Re number increases, the PEMFC maximum temperature, temperature difference and index of uniform temperature (IUT) of water, nanofluid and liquid metal cooling modes decreased significantly than those of heat transfer oil cooling mode. While the heat transfer oil cooling mode has the lowest IUT and the highest peak temperature because of more oxygen involved in the side reaction. The relatively low temperature in PEMFC with liquid metal cooling mode will increase the water content of the membrane and improve the proton conductivity. In addition, at T_in = 345 K and Re = 900 condition, the net power of PEMFC with liquid metal cooling mode is up to 128.23 W, which is 1.62 % higher than that of water cooling mode. This confirms that the application of liquid metal coolant in thermal management system can effectively improve the performance of PEMFC.