As a natural refrigerant

CO2 has advantages such as environmental friendliness

safety and high volume cooling capacity. Therefore

the application of transcritical CO2 systems in large cold storages will improve energy efficiency

reduce carbon emissions and promote environmental protection. The performance and energy consumption characteristics of different refrigeration systems were compared through a comprehensive annual hourly energy consumption analysis

based on different temperature range cold storage demand and various climate conditions. The results show that the transcritical CO2 system integrated with specifically optimized ejector can achieve energy savings of 7.9%

10.1% and 10.5% in for low temperature (-32°C)

medium temperature (-8°C) and high temperature (0°C) cold storages compared with the traditional R507 system; the energy saving of R717 system is 8.1%

2.7% and 7.2% compared with the R507 system

respectively. The energy saving of the R717 system is slightly higher than that of the CO2 system in the low temperature cold storage

but the advantages of the CO2 system are more obvious in the medium and high temperature cold storage. Considering the influence of different climate zones

the energy saving of the CO2 system can reach 9.3% in the cold climate zone

better than the R717 system; while in the hot climate zone

its energy saving drops to 2.8%

slightly lower than that of R717. With appropriate selection of temperature range and climate zone

the overall operation efficiency and energy saving performance of the transcritical CO2 system can be better than the R717 system. This paper conducts a comprehensive analysis on the energy consumption distribution characteristic of the CO2 system

and points out its applicability in different application scenarios

providing important references for the promotion and application of the system. In conclusion

the application of transcritical CO2 refrigeration system with ejector in large cold storage

can significantly reduce both direct and indirect carbon emissions

decrease overall energy consumption

will play great role in achieving dual carbon goals.