A continuous hydrogen absorption/desorption model for metal hydride reactor coupled with PCM as heat management and its application in the fuel cell power system

Abstract

In this work, the model of metal hydride reactor coupled with phase change material (PCM) as heat management is modified to describe the heat and mass transfer behaviors of the continuous hydrogen absorption/desorption processes better. Through the experimental validation, the modified model is proven to be more accurate than the traditional model. Based on the proposed model, the performance of the metal hydride reactor is further optimized by the parametric analysis, property and configuration modification. The results show that the metal hydride reactor achieves a hydrogen storage efficiency of 47% at the phase change temperature of 42 °C, which is higher than at 35 and 49 °C. By adding expanded graphite into PCM, the hydrogen storage efficiency can increase up to about 72%, which is higher than the previously reported efficiency of 69%. This is because of the enhanced heat transfer between metal hydride and PCM. Accordingly, the hydrogen absorption time is significantly shortened to no more than 5 min. In addition, it is suggested to operate the reactor in the hydrogen desorption pressure of 2–8 bar and the temperature of 32–58 °C for the improved performance, when this kind of reactor is applied in the fuel cell power system as hydrogen source.