ENERGY AND ENVIRONMENTAL ANALYSIS OF TRANSCRITICAL CO2 SUPERMARKET REFRIGERATION CYCLES WITH DEDICATED MECHANICAL SUBCOOLER

Refrigerants with high environmental impact are being prohibited by legal authorities. The commercial refrigeration sector, a huge contributor to emissions, is transitioning to environmentally friendly CO2 systems. Despite the environmental benefits of CO2, its low critical temperature and high operation pressure can lead to lower performance in warm climates compared to other refrigerants. Therefore, performance improvements are being made for transcritical CO2 refrigeration cycles. This paper presents energy and environmental analysis of transcritical booster (BRC), parallel compression (PRC), and ejector expansion (ERC) supermarket refrigeration cycles with dedicated mechanical subcooler (DMS) as well as transcritical cycles without DMS circuits, and subcritical R404A conventional system. R134a, R1234yf, and R290 were studied as working fluids for DMS circuits. Annual energy consumption and total equivalent warming impact (TEWI) values were compared for İstanbul, Konya, and Samsun in Türkiye, which are in different climate zones, as a case study. The case study constitutes the novelty of this paper. Up to 11% annual energy savings were obtained using CO2 cycles with DMS compared to R404A conventional system. CO2 cycles have up to 58.4% lower total TEWI values than R404A conventional system