Thermodynamic Performance of Transcritical CO₂ Two-stage Compression Direct Cooling Ice Making System with Complete Inter-cooling

To reduce the energy consumption of a CO₂ ice-making system and improve system performance, this study proposes a transcritical CO₂ two-stage compression ejector expansion direct cooling ice-making system with complete intercooling (TCEIS). The effects of key parameters on system performance were analyzed by developing a thermodynamic model. Using this model, the COP_R+HR, annual power consumption, heat recovery capacity, annual operating cost, and heat recovery income of the system applied in different seasons and cities were evaluated and compared with those of a two-stage compression direct cooling ice-making system (TCS), a two-stage compression direct cooling ice-making system with complete intercooling (TCIS), and an ejector expansion direct cooling ice-making system (ES). The results show that TCEIS has the highest COP_R+HR considering heat recovery, with the advantages being noticeable in hot seasons and cities. When operating in Guangzhou with cooling loads of 410.989 kW in winter, 542.092 kW in transition seasons, and 701.353 kW in summer, the annual operation cost of TCEIS can be reduced by 107.6 thousand yuan, 397.9 thousand yuan, and 583.1 thousand yuan compared with those of TCIS, TCS, and ES, respectively. This study provides a theoretical reference for the construction and application of CO₂ direct-cooling ice-making systems.