Study on the performance of a high-solar-efficiency ejector-compressor-partially-coupled refrigeration system with cooling storage at sub-low temperature

Solar-driven ejector-compression combined refrigeration holds significant importance in reducing building energy costs and carbon emissions. However, existing systems encounter challenges including low thermal efficiency, large thermal storage device, and thermal storage heat loss, reducing energy-saving potential. Aiming at this, a high-solar-efficiency ejector-compression partially-coupled refrigeration system with cooling storage at sub-low temperature is proposed in this paper. The new system can efficiently utilize solar energy to partially produce cooling energy at sub-low temperature. And this cooling energy is much less than driven heat and close to ambient temperature, reducing thermal storage device size and heat loss. A theoretical model was established with the ejector model experimentally validated. Results show that the maximum cooling storage mode has better performance, with maximum COPoe and COPog of 10.72 and 3.25 respectively, which are 16.9 % and 13.3 % higher than no cooling storage mode, respectively. Compared to the traditional ejector-compression system and its auxiliary system, the new system shows superior performance, with COPoe improvement of 19.7 % and 14.5 %, and COPog improving by 21.5 % and 17.0 %, for maximum and partial cooling storage modes, respectively. These results show good energy efficiency of the system and provide a more energy-efficient solution for solar driven ejector-compression refrigeration systems.