Analysis and improvement of flow distribution in manifold for proton exchange membrane fuel cell stacks

Abstract

The flow distribution in manifold has significant effect on the output performance of the stack according to the Cannikin Law, especially for multi-cell proton exchange membrane fuel cell (PEMFC) stacks. This study presents an analytical model which simultaneously considered local pressure losses, pressure recovery phenomenon, electrochemical reactions, and liquid water to calculate the flow distribution using the flow network method. Both U-shape and Z-shape flow configuration stack are investigated. The analytical model is simultaneously and quantitatively validated with three distinct variables (the dimensionless mass flow rates, the stack pressure drop and the pressure distribution in manifold) to ensure the accurateness of modelling results. Effects of reactant consumption and two-phase flow in unit cell on the flow distribution are quantitatively investigated. Results show that the flow maldistribution is overestimated when ignoring gas consumption and two-phase flow for both 200-cell U-shape and Z-shape stack. Balance the pressure drop of inlet and outlet manifold significantly improves the flow distribution for U-shape stack. Finally, the differentiated assembly strategy is first proposed to improve the flow distribution in manifold for multi-cell PEMFC stacks. Compared to the original design, the ratios of the improvements for 200-cell U-shape and Z-shape stack are 85% and 25%, respectively.