The effect of compressive load on PEM fuel cell stack performance and behavior

Two-dimensional and three-dimensional models of a Proton Exchange Membrane (PEM) fuel cell stack are developed. Taking advantage of the geometrical periodicity of a typical stack assembly, the model is used to predict the detailed thermal, humidity, and electrochemical distributions within the fuel cell. Using recently-reported as well as new experimental results, the electrical and thermal contact resistances and modifications in the gas diffusion layer transport properties that develop within the stack in response to changes in the compressive force used to assemble the stack, are accounted for. Of particular interest is the effect of the compressive force used to assemble the stack on the fuel cell\u27s (a) power output and (b) internal temperature distribution. The fuel cell stack performance, reported in terms of its power output and internal temperature distributions, is very sensitive to the compressive load. Application of non-uniform clamping pressure is considered, and predictions suggest that thermal conditions within the stack can be made more uniform with negligible impact on the fuel cell power. Hence, improved fuel cell stack durability might be achieved through prudent application of non-uniform clamping pressures for stack assembly.