Performance evaluation of a multi-stage plate-type membrane humidifier for proton exchange membrane fuel cell

•Performance of multi-stage membrane humidifier for fuel cell was studied.•Air flow rate of 30 L per min provides the best thermal performance.•Both width and depth of the channel have remarkable effect on the humidifier performance.•Minimum air flow rate, inlet temperature, and humidity are the efficient operating conditions. The influence of channel dimension and altering dry air inlet conditions such as temperature and humidity on the humidification efficiency of a multi-stage plate-type membrane humidifier for kW-scale proton exchange membrane fuel cells is analyzed in terms of the dew point approach temperature, water recovery ratio, pressure loss, and the coefficient of performance. Investigating the effect of channel dimension reveals that the width and depth of the channel significantly affect the humidification performance. The results show that the increase of dry air inlet temperature and humidity leads to improving the dew point approach temperature, decreasing the water recovery ratio, slight increasing the pressure drop, and consequently decreasing the coefficient of performance. The minimum dew point approach temperature and maximum water recovery ratio occur at the flow rate of 30 L/min. The highest water recovery ratio, 73%, is achieved at the temperature of 50 °C and relative humidity of 40%. Moreover, the pressure loss increases with the increment of air flow rate and the coefficient of performance declines with the increase of air flow rate. Thus, it is recommended to select the minimum possible flow rate, dry air inlet temperature, and relative humidity as the efficient operating condition.