Performance analysis of solar powered vapour absorption refrigeration system with cold thermal energy storage for sub-zero cooling application

Abstract This research evaluates the performance of a solar-powered ammonia-water vapor absorption refrigeration system (SVARS) with cold thermal energy storage (CTES), designed to provide continuous sub-zero cooling while offering an eco-friendly, sustainable refrigeration solution that mitigates ecological concerns by avoiding the emission of climate damaging gases. It employs a 144 m 2 area of evacuated tube solar collectors with compound parabolic concentrating (CPC-ETC) capable of supplying thermal energy at a temperature ranging from 140 to 166 °C to operate the SVARS. The refrigeration cycle is integrated with a 0.85 m 3 CTES unit containing undecane (C₁₁H₂₄) phase change material (PCM), while a glycol solution serves as a coolant. The model combines MATLAB for unsteady thermal analysis of CP-ETC and PCM, alongside Engineering Equation Solver (EES) for the thermodynamic analysis of the absorption refrigeration cycle. The predictive accuracy of the simulation is confirmed with previously published results. The system with 17.8 kW cooling capacity is designed to maintain a freezer room below –18 °C throughout a full 24-h period. It achieves a minimum evaporator temperature of –37.3 °C, with average freezer room heat exchanger outlet coolant temperatures of –22.3 °C under the lowest solar irradiation (LSI) and –25.02 °C under the highest solar irradiation (HSI). The energetic performance (COP th ) ranges from 0.33 to 0.47, whereas the system coefficient of performance (SCOP) is 0.20 and 0.23 under LSI and HSI, respectively. The CPC-ETC collectors sustain thermal efficiencies in the range of 0.579 to 0.600. Additionally, an economic assessment incorporating environmental damage costs is performed for the designed system; an initial investment cost of $58,797 yields a levelized cost of energy (LCOE) of $0.06774/kWh with a payback time of 10.5 years. The study provides a validated numerical model and performance information for a CTES-SVARS integrated in subzero cooling applications, confirming that cold energy storage is a feasible method for independently manage cooling generation and demand.