Effective Thermal Conductivity of Gas Diffusion Layer in Through-Plane Direction

Temperature remarkably influences the water behavior in the PEMFC. However, the temperature inside the PEMFC has not been well understood. A lot of heat comparable to the electric power is emitted out of the cell. The PEM temperature is determined by the effective thermal conductivity through the layers and the temperature gradient created in the through-plane direction for emitting the heat. By measuring the PEM temperature with thin thermocouples and thick membrane, the effective thermal conductivity was estimated. It strongly depended on the cell binding pressure. Binding the cell improves the contact between carbon paper and carbon current collector as well as compresses carbon paper, leading to rise in the apparent effective thermal conductivity in the through-plane direction. The interfacial resistance to heat transfer was found 39 % of the overall resistance.