Multi-response optimization of ejector for proton exchange membrane fuel cell anode systems by the response surface methodology and desirability function approach

Abstract

ABSTRACT In a fuel cell system, the performance of the ejector is limited when it operates under off-design conditions. To improve the performance of the ejector under all operating conditions in the fuel cell system, this study employs a multi-response optimization approach to optimize the structural parameters of the ejector. The optimization objectives are the entrainment ratio under low-power and high-power operating conditions, with the optimization variables including the mixing tube diameter (D m ), primary nozzle exit position (L nxp ), and mixing tube length (L m ). A quadratic polynomial model is proposed to correlate the key structural parameters of the ejector with the entrainment ratio using the response surface methodology based on the Box-Behnken design. The optimal structural parameters of the ejector are obtained using the desirability function approach. The results demonstrate that this optimization approach significantly improves the ejector performance under off-design conditions while the performance remains essentially unchanged under high-power operating conditions.