Performance estimation of dehydriding process in metal hydride hydrogen storage tank with coiled-tube heat exchanger

Various thermal management methods are widely adopted in the metal hydride (MH) system to release the thermal effect and obtain acceptable hydrogen storage performance. In this work, an axisymmetric numerical model for a simple MH system without a heat exchanger (HE) has been established and validated to study the system performance during dehydriding. Then the coiled-tube heat exchanger (CTHE) and the phase change material heat exchanger (PCMHE) are used in the hydrogen storage system to improve heat transfer and release negative thermal effect, respectively. The performance of the MH-CTHE system and the MH-PCMHE has been estimated in the dehydriding process. CTHE shows more obvious impact than that of PCMHE. Effects of three common operation parameters on the hydrogen storage capacity of the MH-CTHE system have been investigated. The research results show that the influences of the heating water temperature and the outlet pressure on the system performance are more prominent than that of the heat transfer coefficient. In addition, the relationship between the average dehydriding rate of the MH-CTHE system and the two main operation parameters has been fitted as a simple equation, which can be used to predict and control the dehydriding rate based on given operation conditions.