CO2 is considered to have great application potential in cold storage due to its low global warming potential and zero ozone depletion potential. In this study

a mathematical model was established for a CO2 transcritical two-stage compression refrigeration cycle with complete inter-cooling and double-stage throttling (DTCC cycle) used in cold storage applications. The effects of evaporation temperature

compressor efficiency

gas cooler outlet temperature

discharge pressure

and heat recuperative cycle on the refrigeration coefficient of performance (COP) of the cycle were analyzed atdifferent working conditions. The correlation of optimum discharge pressure and intermediate pressure under a maximum COP was given. When the evaporation temperature te = -30–10 ℃ and the gas cooler outlet temperature tgs = 30–45 ℃

the optimal discharge pressure of the two-stage cycle is approximately 0.3 MPa less than that of the single-stage transcritical refrigeration cycle under the same working conditions. Further analysis showed that the refrigeration coefficient of the DTCC cycle was improved by using anadditional gas cooler for low-pressure discharge gas and by setting arecuperatorat the outlet of the high-pressure gas cooler.