Experimental investigation of the effect of copper coating and ENG addition on the hydrogen storage kinetics of metal hydride pellets

In this study, metal hydride pellets were developed to enhance the kinetics of hydrogen charging/discharging processes. By incorporating ENG (expanded natural graphite) and copper additives, improvements in the heat transfer coefficients and storage capacities of hydrogen storage materials have been realized. The reactor is designed to contain 1000 g of storage material in the powder form or 25 pellets each weighing 40 g. The effect of storage materials with increased thermal conductivity on the hydrogen charge/discharge process has been experimentally studied in a metal hydride reactor under a pressure of 10 bar. To complete the activation process, the reactor was heated under vacuum (10-4 mmHg) at about 200 °C for 2 hours. After the heating process, the reactor was allowed to cool down to ambient temperature and then hydrogen was charged into the reactor at a pressure of 10 bar for 50 minutes. The hydrogen charging/discharging procedure was repeated for up to 20 cycles and data records were taken at 5 cycle intervals to monitor changes between 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.