Numerical Investigation of Energy Desorption in Dual Metal Hydride Bed Based Thermochemical Energy Storage System
Abstract
Among thermal energy storage (TES) systems, thermochemical energy storage (TCES) systems are known for high energy storage density. Metal hydride (MH) based TCES system, due to its good chemical reversibility and higher thermal stability, found suitable for high temperature TES applications. Many studies have reported the improvement in energy storage characteristics with enhancement in the heat transfer phenomenon in dual MH bed systems. The study investigates the discharging characteristics of a dual MH bed system for high temperature thermal energy release process. The dual metal hydride bed system includes a high temperature metal hydride (HTMH) bed, which works as energy storage media operating at high temperatures and a low- temperature metal hydride (LTMH) bed, used as hydrogen storage media. NaMgH2F is used as HTMH, while Mg2NiH4 is used as LTMH. The heat transfer phenomenon, energy discharging characteristics, and hydrogen transfer during thermal energy release from HTMH are studied. The energy desorbed from the MH bed for thermal conductivity 0.5 W/m K, 0.75 W/m K, and 1 W/m K are found as 251.25 kJ, 258.22 kJ, and 260.57 kJ, respectively. Hydrogen absorbed in the HTMH during thermal energy desorption for thermal conductivity 0.5 W/m K, 0.75 W/m K, and 1 W/m K are 6.94 g, 7.13 g, and 7.17 g, respectively. The heat transfer phenomenon in HTMH bed has improved with the increase in thermal conductivity of HTMH, and hence, the heat desorption characteristics also improved. The thermal energy discharging rate from HTMH also increased with the increase in the thermal conductivity of the HTMH bed.
Keywords
Concentrating solar power, Thermochemical energy storage, High temperature thermal energy storage, Dual metal hydride system.