Research on the variation of current density distribution in a commercial-size proton exchange membrane fuel cell under dynamic gas operation parameters

Abstract

Proton exchange membrane fuel cells are considered as a promising alternative energy conversion device and its performance is largely affected by operation parameters. Among these parameters, stoichiometric ratio and back pressure can be properly controlled in practice and have a significant influence on the performance, but the mass transfer process in a fuel cell is seriously restricted. Therefore, the variation of overall performance and current density distribution of a commercial-size proton exchange membrane fuel cell under dynamic gas operation parameters especially during transient process is detailly investigated in this paper. Experiments are conducted with dynamic gas operation parameters using segmented cell technology. Cathode stoichiometric ratio serves as a better operation parameter than back pressure when attempting to affect the cell performance timely and effectively. Effect of back pressure drop under different situations are analyzed. During a short transient process, a large increase of cathode stoichiometric ratio leads to an instant performance increase of area far away from cathode inlet and thereby cause an increase of cell performance. This work leads to suggestions on the control strategy during dynamic load demands and lays a foundation for further study into the durability under variable gas operation parameters of the fuel cell operation.