Performance Analysis of Supermarket Subcooling CO2 Refrigeration System Integrated With Seasonal Borehole Cold Energy Storage

In order to meet the requirement of energy conservation and carbon reduction in commercial supermarket refrigeration applications, a supermarket subcooling CO2 refrigeration system integrated with seasonal borehole cold energy storage is proposed. The cold energy can be stored in the soil in winter and utilized in summer to cool the CO2 fluid flowing from the gas cooler, which can improve the performance of CO2 refrigeration system under the working condition of high ambient temperature. Based on the thermal resistance-heat capacity model of the soil cold storage and release system, a typical dynamic simulation model of supermarket subcooling CO2 refrigeration system integrated with seasonal borehole cold energy storage is established. Beijing and Harbin are selected as typical operating scenarios, and the temperature distribution of soil cold storage and release system is analyzed. Moreover, the system thermodynamic performance and coefficient of performance (COP) is further analyzed. The results show that the operation mode of cold storage/release is closely related to the city climate condition, and higher subcooling degree and discharge pressure are obtained for the city with higher ambient temperature. The system energy efficiency improvement is more significant in areas with higher ambient temperature when the technique of seasonal borehole cold energy storage is adopted. The average COP improvement rates of the CO2 refrigeration system with subcooling in Beijing and Harbin are 8.97% and 8.33%, respectively, compared with that without subcooling. © 2023 Science Press. All rights reserved.