Applying solar-powered ejector subcooling to supermarket CO2 refrigeration system for improving the performance

Abstract

The problem of energy efficiency degradation of supermarket CO₂ refrigeration system when operating in high temperature region has been the key limitation of the application of the system. To address this problem, this article proposes a solar-powered ejector subcooling system integrated with supermarket CO₂ refrigeration system (ES-SCRS). The performance of the system is enhanced by utilizing solar energy. The mathematical model is established and the effects of key parameters such as solar radiation intensity and ambient temperature on the performance are investigated through parametric analysis. Guangzhou in China is selected as the research object, applying coefficient of performance (COP) and seasonal energy efficiency ratio (SEER) as evaluation indicators to analyze the energy saving potential of ES-SCRS compared to the conventional supermarket CO₂ refrigeration system (SCRS). The results show that when ambient temperature is 40°C and radiation intensity is 300–1200 W/m², the COP_m enhancement is 6.52 %-24.21 %. On typical days, the COP_m enhancement of ES-SCRS compared to SCRS in summer is most obvious, ranging from 4.56 % to 20.07 %. Meanwhile, COP_m improvement during spring, autumn, and winter is 2.14 %-11.56 %, 1.51 %-13.57 %, and 3.35 %-11.49 %, respectively. The SEER of ES-SCRS is increased by 5.01 % over SCRS during the summer and the total power consumption is decreased by 4.33 % compared to SCRS. Therefore, the proposed system in article can enhance the performance of the CO₂ supermarket refrigeration system and provide a solution for the application in high temperature environments.