The effect of powder and pellet forms of added metal hydride materials on reaction kinetics and storage

Abstract

In the present research, metal hydride pellets were synthesized to enhance the kinetics of hydrogen charge/discharge processes. By incorporating ENG (expanded natural graphite) and copper additives, we observed improvements in the heat transfer coefficients and storage capacities of the hydrogen storage materials. The reactor is designed to contain 1000 g of storage material in the form of powder or 25 pellets each weighing 40 g. The influence of storage materials with enhanced thermal conductivity on the hydrogen charge/discharge process was experimentally studied in a metal hydride reactor under a pressure of 10 bar. The reactor was heated under vacuum (10−4 mmHg) to approximately 200 °C for 2 h in order to complete the activation process. Following the heating process, the reactor was allowed to cool to ambient temperature, after which the hydrogen was introduced to the reactor at 10 bar pressure for 50 min. The absorption and desorption procedure was reiterated up to 20 cycles, and recordings of data were taken at intervals of 5 cycles to monitor the variations between the cycles. After 10 charge/discharge cycles under pressure of 10 bar, the hydrogen stored in the reactor amounted to approximately 9.93 g in pellet form and 7.20 g in powder form.