A novel gas supply configuration for hydrogen utilization improvement in a multi-stack air-cooling PEMFC system with dead-ended anode

Abstract

The gas supply configuration would influence the reactant distribution, output performance, and durability of multi-stack proton exchange membrane fuel cells (PEMFCs). However, few researches have been conducted on optimizing the gas supply configuration. In this work, the hydrogen supply systems of two air-cooling PEMFC stacks under dead-ended anode (DEA) mode are connected in parallel and series configuration, and effects of configuration method on the performance, uniformity, and purging characteristics of these PEMFC stacks are studied. The experimental results show that series configuration provides higher power output at the expense of lower fuel utilization in comparison with parallel configuration. The main cause for the voltage degradation of PEMFCs systems under DEA mode is the accumulation of impurity gas in the outlet of PEMFC stack. Therefore, an optimized series gas configuration is proposed by adding a buffer tank and solenoid valves at the outlet of PEMFC system to purge and store the impurity gas. The optimized series configuration extends purging interval from 125 s to 800 s at the current density of 200 mA cm−2 without parasitic power. The fuel utilization has been improved from 97.51% (in series), 98.87% (in parallel) to 99.21% (in optimized series).