A three-dimensional analysis of the effect of anisotropic gas diffusion layer(GDL) thermal conductivity on the heat transfer and two-phase behavior in a proton exchange membrane fuel cell(PEMFC)

A three-dimensional and two-phase model was employed to investigate the effect of the anisotropic GDL thermal conductivity on the heat transfer and liquid water removal in the PEMFCs with serpentine flow field and semi-counter flow operation. The GDL with different anisotropic thermal conductivity in the three directions (x, y, z) was simulated for four cases. As a result, the water saturation, temperature, species, current, potential distribution and proton conductivity were obtained. According to the comparison between the results of each case, some new conclusions are obtained and listed as below: (1) The anisotropic GDL produces the high temperature difference than that of isotropic case, and the in-plane thermal conductivity perpendicular to the gas channels is more important than that of along channels, which may produce the larger temperature difference. (2) Water saturation decreases due to the large temperature difference in the anisotropic case, but some water vapor may condense in the area neighbor to the channel ribs due to the cool function of the current collector and the great temperature difference. (3) The anisotropic thermal conductivity in the through-plane direction and the in-plane direction perpendicular to the gas channels can lead to the decrease of the membrane conductivity. (4) The isotropic GDL is better than that of anisotropic one for the uniform current density. Also, in-plane thermal conductivity perpendicular to the channels has more negative effect on the current density distribution in the membrane than that of the along channels one.