Comprehensive performance evaluation of air-assisted atomization humidification for high-power fuel cell systems

Membrane humidification is the most prevalent method used to humidify the fuel cell system of commercial vehicles. However, this passive approach meets only the humidity requirements. In order to simultaneously address the issues of humidification and cooling associated with high-power fuel cell systems，air-assisted atomization humidification (AAAH) is proposed as an active technology. However, there are not enough experiments to evaluate the adaptation of AAAH. In this study, the impacts of spray parameters are observed under high-power load conditions and then compared with that of membrane humidification (MH) under various operating scenarios. Experimental results show a positive correlation between the relative humidity of the cathode inlet and the pressure of spray with AAAH. Moreover, this technology achieves higher relative humidity of the cathode inlet and water recovery rate than those obtained by MH, enhancing the stack performance and system efficiency and reducing system thermal load. At the rated current of 540 A, the system efficiency can reach up to 44.8 %. Although the humidity fluctuates in the range of 26.3 % to 53.2 % under variable load conditions, with a response time of 41 s, which is longer than that of MH, the fluctuations are within an acceptable limit considering the stack performance. Finally, an optimized control strategy based on the proportion of liquid water is applied to achieve the reuse of humidification from the liquid water removal at the cathode outlet at full operating conditions.