Thermodynamic analysis of La and Mm based metal hydride pairs for solar energy-driven cold storage applications

Abstract

Cold storage plays a vital role in many applications such as agricultural and food processing units. Metal hydride-based sorption cold storage systems are environmentally friendly as they use hydrogen. In the present study, La and Mm metal hydrides based cooling system is proposed for cold storage application which can work using solar energy. Ten metal hydride (AB5) pairs were selected for the thermodynamic analysis of the cold storage module. The minimum cooling temperature and maximum heat source temperature required for each pair are calculated. Hydrogen storage and thermodynamic properties of La0.95Ce0.05Ni5, La0.85Ce0.15Ni5, and MmNi4.5Al0.5 are obtained by measuring pressure concentration isotherms at different temperatures. The effect of source temperature and cooling temperature on COP, Exergy COP, and specific cooling load (SCL) are studied. MmNi4.6Fe0.4/MmNi4.6Al0.4 pair has attained a theoretical maximum COP and exergy COP of 0.784 and 0.89 respectively at a heat source temperature of 60 °C and cooling temperature of 2 °C. However, at higher heat source temperature La0.95Ce0.05Ni5/MmNi4.5Fe0.5 has better performance than MmNi4.6Fe0.4/MmNi4.6Al0.4. In addition, the effect of cooling load on the size of the system for cold storage of 10 kg apples is also studied. For cold storage of 10 kg apples at 2 ℃, La0.95Ce0.05Ni5/ LaNi4.7Al0.3 has the best performance with a COP of 0.693 and minimum total weight of 18.35 kg.