Investigation on the adaptivity of the transcritical CO2 refrigeration system with a capillary

In order to research the adaptivity of the capillary tube in the transcritical CO₂ refrigeration system, a separated flow model of a CO₂ capillary in which the metastable phenomenon was taken into consideration was built in the simulation of transcritical CO₂ refrigeration system, and related experiments were carried out by a plant under different gas-cooler outlet temperatures. The performances of the capillary based system were further compared with that of the EEV (electronic expansion valve) based system. The results showed that the relative COP ranged from 82% to 98% when there was a 10°C deviation between the real gas-cooler outlet temperature and the design value. Thus the capillary based transcritical CO₂ system is promising and could achieve performance close to that of EEV based system in a wide range of gas-cooler outlet temperature.