Development, exergo-energetic, and environmental analysis of a novel energy-efficient solar-assisted refrigeration system using natural fluids

This paper proposes and develops a novel refrigeration system, combining the vapour compression refrigeration cycle with an open PTC solar driven Brayton cycle operating with low GWP/ODP natural refrigerants, for improved energy and environmental performances. The aim of this work is to develop a model for the energy and exergy analysis of the system, select the most appropriate natural fluid, and then assess the energy savings that can be made, as well as the environmental impact, under different system operating conditions. The developed system model based on conservation of mass and energy was simulated using EES software, for a cooling capacity of 15 kW, a solar irradiation of 500 W/m² and an evaporation temperature of −25°C. The TEWI method was used to assess the environmental impact. The R717 refrigerant has been identified as the best-performing working fluid for system operation, with a COP of 5.88, an exergy efficiency of 33.37 % and a TEWI of 279.2 tCO 2 eq, representing a 46.3 % reduction in environmental impact. Simulations showed that energy savings vary with the mass flow fraction and the latter can be controlled by the flow regulator during low cooling demand. Based on simulation results the proposed refrigeration system can achieve up to 73 % of energy savings at a maximum irradiation of 1000 W/m² when operating with R717.