Study of Flow Field Design for Improving PEMFC Performance

PEMFC stacks are construction of single cells typically joined with bi-polar plates. Usually, the stack performance (total voltage/number of cells in the stack) is less than a single cell at the same current density. The performance of a stack not only depends on the conductivity of the plates but also on the flow field design for maintaining uniform humidity and hydration of the MEA in each cell. The objective of the study is to understand the physics in the flow field and show the effects of the flow field geometry changes on the cell performance. In this work, numerical model of PEMFC will be developed for a 25-cm single cell and will be scaled up to 200-cm reacting areas for various flow field patterns. The numerical results will predict the distribution of local current density, water (liquid and vapor), temperature, and pressure. These results will be compared with the experimental data. The numerical results will show the effect of scale-up and flow pattern design on PEM fuel cell performance. The model will also show the changes in the local flux of water due to the electro-osmotic controlled or back diffusion controlled for different flow field designs and operating conditions.