Effects of Inhomogeneous Gas Diffusion Layer Properties on the Transportation Phenomenon and Performances of Proton-Exchange Membrane Fuel Cells.

Abstract

The encapsulation of the proton-exchange membrane fuel cell (PEMFC) is an essential step of fuel cell stack assembly. The selection of the assembly pressure is very important to the stack performance and life. Based on that, this paper presents a method to describe the internal physical deformation of the gas diffusion layer (GDL) after inhomogeneous pressure by using user-defined functions (UDFs). The results show that the transmission difference caused by the nonuniform GDL deformation can be clearly seen by the UDFs method, and there is an obvious transition of GDL at the interface of the channel and the rib. A three-dimensional single-channel PEMFC model is established, and an optimal assembly pressure range is obtained, between 1.5 and 2.0 MPa. The maximum thermal stress inside the cell occurs in the middle of the membrane electrode assembly and decreases as the assembly pressure increases. Furthermore, the influence of rib-channel ratios is discussed. Compared to the fuel cells with ratios of 2:1, 2:3, and 1:2, the one with 1:1 exhibits the maximum current density and the highest power density.