The enhancement of metal hydride hydrogen storage performance using novel triple-branched fin

Abstract

The advantages of a high storage capacity and safety of metal hydride hydrogen storage (MHHS) have widely attracted people's interest in hydrogen storage. The improvement of the heat transfer performance is one of the key parameters to improve the overall MHHS performance. Various heat exchangers with complex structures have been developed for this purpose. However, the drawback of these heat exchangers is huge pressure losses. Therefore, this study aims to enhance the MHHS performance by considering the heat transfer improvement and maintaining the pressure loss inside the heat exchanger. To fulfil the requirement of heat transfer efficiency instead of using complex heat exchangers, a novel triple-branched fin is designed to attach to the simple straight tube heat exchanger. The effect of pressure losses due to the complex heat exchangers is analysed and compared with the simple straight tube. The novel fin heat exchanger's performance is also compared to conventional fins. Moreover, an enhancement of the novel fin geometries is considered with the parametric studies to achieve superior MHHS performance. The results indicate that the pressure losses are reduced by 31 % when using the straight tube instead of other complex heat exchangers. The novel triple-branched fin obtains the best heat transfer performance compared to other fin designs, including the quadrilateral fin and Y-shaped fin. After the geometrical enhancement of this novel fin, the duration of the absorption-desorption cycle is reduced by 25 % compared to the quadrilateral fin. Under the parametric study, heat transfer fluid temperature significantly affects the desorption process, while the heat transfer coefficient greatly affects the absorption process.