Auxiliary-ejector-based hydrogen recirculation system to broaden PEMFC operating range

This study presents an auxiliary-ejector-based hydrogen recirculation system to widen the operating range of the proton exchange membrane fuel cell system (PEMFCS). An auxiliary ejector (BE) design model is presented and then an experimentally verified two-dimensional numerical-simulation model is built to study the relationships between PEMFC output power, ejector geometrical parameters, and its performance (mu) based on sensitivity analysis. Finally, the operating characteristics of the BE are clarified. The results show that the mu is highly sensitive to position (L-b), followed by width (w) and angle (A) of auxiliary port. The BE can provide satisfactory mu above 0.8 under higher power output, and a mu higher than 0.6 for lower power output with the L-b, A, and w of 1.1, 30 degrees, and 4 mm when PEMFCS works from 17.9 to 84 kW. This proposed system can extend the operation range of PEMFCS using a single ejector, which can contribute to fuel cell development.