Experimental determination of the water vapor effect on subsonic ejector for proton exchange membrane fuel cell (PEMFC)

Abstract

A test facility for experimental determination of the ejector, used in the anode recirculation loop of the polymer electrolyte membrane fuel cell (PEMFC), was set up in this paper. Based on a 1-dimensional constant-pressure mixing model, an ejector with a convergent nozzle and a cylindrical mixing tube was designed. By the test facility, entrainment ratio and hydrogen mole recirculation ratio of the designed ejector were tested on different conditions, corresponding to the PEMFC stack operation protocols. The difference of the entrainment ratio and the mole recirculation ratio effectively shows the influence of water vapor on the actual recirculation quantity of hydrogen fuel. Results show when the hydrogen was saturated humidified at 60 °C, the entrainment ratio of the designed ejector ranged from 2.3 to 2.8, changing the primary flow rate from 26 to 38 standard liters per minute (SLPM) and the mole recirculation of hydrogen ranged from 0.75 to 0.8.