A numerical study on heat transfer for serpentine-type cooling channels in a PEM fuel cell stack

The aim of this work is to analyse numerically the heat transfer for serpentine-type cooling channels in a PEM fuel cell stack. The effect of the coolant type, the flow rate, the inlet temperature, the presence of the thermal contact resistance and the gas diffusion layer, the bipolar plate material and the cooling channels design was studied with CFD simulations in a 100 cm2 active area cell with serpentine cooling channels to analyse the refrigeration capability of a PEMFC stack. A novel correlation for the Nusselt number is presented. The originality of the proposed correlation lies in the fact that it can be used for a comprehensive range of operating conditions, coolant fluids and bipolar plate materials, assessing the influence of those variables on the temperature distributions within the cell. Results of this study determined that mass flow and the bipolar plate thermal conductivity presented a higher effect on the refrigeration capability of a PEMFC stack. Results obtained in terms of the Uniform Temperature Index showed that values above 3.65 % lead to temperature differences in the membrane higher than 5 K, which could cause degradation problems.