Study on the thermodynamic performance of solar absorption refrigeration combined with a ‘seasonal cold storage’ system

Inter-seasonal thermal storage technologies are focused on storing and transitioning abundant solar energy from summer to winter for heating, often ignoring the fact that abundant cold energy in winter can also be transferred to summer for cooling. In this paper, a novel solar absorption refrigeration combined with a 'seasonal cold storage' system is proposed to store abundant ambient cold energy in the form of chemical potential in winter and is utilized to discharge energy for refrigeration in summer. Moreover, based on the thermophysical properties of LiBr/H2O, LiBr-[BMIM]Br/C2H5OH and LiBr-[BMIM]Cl/CH3OH, the thermodynamic performances under various operating conditions were calculated via MATLAB. The results show that the system using LiBr-[BMIM]Cl/CH3OH obtained a larger energy storage density of 339.22 kJ·kg−1 below the ice point without freezing compared to traditional ice storage. The systems using LiBr-[BMIM]Br/C2H5OH and LiBr-[BMIM]Cl/CH3OH achieved higher coefficients of performance of 0.94 and 0.90, respectively. Moreover, the generation temperature of the system using both the ternary working pairs was below that of LiBr/H2O by more than 5 K, which was beneficial for enhancing the utilization of solar energy and saving the collector area. Overall, this new system using LiBr-[BMIM]Cl/CH3OH exhibited the shortest payback period of 2.73 a, with considerable economic benefits.