Parametric study of a membrane energy exchanger based on energy, entropy, and exergy analysis for proton exchange membrane fuel cell application

Abstract

The present study adopted the thermodynamic technique to model a membrane energy exchanger (MEE) used for proton exchange membrane fuel cell (PEMFC) application. Governing equations, including a system of three nonlinear coupled equations and several dependent equations, are solved. The present numerical results were compared and validated by an experimental study, indicating a suitable match with a reasonable error. A comprehensive parametric study and sensitivity analysis were conducted in this study based on four efficiency evaluation criteria, including effectiveness, water recovery ratio (WRR), entropy generation, and exergy efficiency. The exergy efficiency comprises the thermodynamic exergy, chemical exergy, and mechanical exergy. The analyzed parameters included temperature at the wet and dry channel entry, pressure at the wet and dry channel entry, and relative humidity (RH) at the wet and dry channel entry. A to D ratings were assigned to these parameters. When three criteria show positive results by enhancing each parameter, the A rating is assigned to that parameter, representing the optimal efficiency. For example, enhancing the dry channel entry temperature from 306 to 318 K leads to a 30.5% enhancement in WRR, a decrease in DPAT, an 11% improvement in exergy efficiency, and a reduction in entropy generation. Since all four criteria were desirable, enhancing the dry channel entry temperature was rated A and is highly recommended.