Transcritical CO2 system has become a hot topic in the field of heat pumps and air conditioning. In this paper

the CO2 gas cooler was taken as a research subject. The system entransy dissipation was produced by the temperature difference of heat transfer and flow resistance of inside and outside fluid. A steady state distributed parameter model for the transcritical region of CO2 gas cooler was established to solve entransy dissipation number . The main reason of entransy dissipation number generation and its distribution were analyzed. Meanwhile

the effects of CO2 and entrance parameters of water on the system entransy dissipation number were discussed. Results from the mathematic model showed that system entransy dissipation was mainly caused by temperature difference of heat transfer. The more the temperature difference

the bigger the entransy dissipation number. In each infinitesimal segment

the entransy dissipation number and the magnitude of CO2 temperature drop were in an inverse relationship. At the critical point

reached a maximum value. With the increase of mass flow rate and inlet pressure of CO2

the system entransy dissipation number became lager. While with the increase of water mass flow rate

the system entransy dissipation number decreased. Meanwhile

the higher the pressure

the smaller the decreased magnitude of entransy dissipation number. With the increasing of CO2 inlet temperature

the entransy dissipation number decreased. The decreased degree of entransy dissipation number goes down with the increase of CO2 inlet temperature. In addition

the inlet temperature of water has little impact on system entransy dissipation number.