Effect of channel step-depth on the performance of proton exchange membrane fuel cells

Abstract

A three-dimensional model was used to investigate the mass transfer phenomena and pressure drop of proton exchange membrane fuel cells at various step-depths on both straight and serpentine flow patterns. The model is based on the solution of the conservation equations of mass, momentum, species, and electric current in a fully integrated finite-volume solver using the Computational Fluid Dynamic Research Corporation (CFDRC) commercial code. The single cell reaction area and normal depth were 25 cm2 and 1 mm, respectively. The model is altered at variable depths into three modes. The concentration polarization in the normal straight flow pattern improves in the variable step-depth flow pattern. However, gas diffusion behaviour of the normal and variable step-depth serpentine flow patterns are similar. In both, the pressure drop is found to increase with an increase of step-depth. Although more and more step-depth areas are designed for straight flow, the performance and pressure drop of the straight flow pattern infact approach that of the serpentine. Optimization will enhance performance while keeping the pressure drop lower.