Performance evaluation of CO2 supermarket refrigeration system with multi-ejector and dedicated mechanical subcooling

Abstract

In this paper, a CO2 supermarket refrigeration system using multi-ejector and dedicated mechanical subcooling (MEJ + DMS) is proposed to solve the problem of low performance of the CO2 refrigeration system in high temperature area and evaluate the feasibility application in China. A detailed thermodynamic performance analysis is conducted with MATLAB software. Furthermore, the annual energy consumption and seasonal energy efficiency ratio (SEER) are used as the major indicators to assess the system performance in five typical representative cities of diverse climate types in China. The results indicate that compared with the basic booster system (BASE), the system with dedicated mechanical subcooling (DMS), and that with multi-ejector (MEJ), the MEJ + DMS system permits not only reducing the operating pressure of the system but also enhancing the maximum COP by 61.76%, 19.17% and 20.21%, respectively at the ambient temperature of 40 °C. Furthermore, the annual analysis shows that the MEJ + DMS system can save energy by 29.94% and increase SEER by 42.73% in hot summer and warm winter zone. The new proposed system has the advantages of greatly promoting system performance and saving energy and is expected to replace the existing CO2 supermarket booster refrigeration systems.

Keywords

• CO2
• Multi-ejector
• Dedicated mechanical subcooling
• Supermarket
• Refrigeration