A trans – critical C02 refrigeration system experimental table equipped with a tube – in – tube gas cooler was utilized to conduct the experiment. The temperature distribution of water in the gas cooler was measured under different CO2 mass flow rates, high side pressure and cooling water volume flow rates. The energy consumption efficiency of the gas cooler was analyzed by entropy generation, exergy destruction and entransy dissipation along the tube. Results show that entropy generation, exergy destruction and entransy dissipation decrease along the tube under a variety of conditions. Entropy generation and exergy destruction reduce with the increase of CO2 mass flow rate, and increase with the rise of high side pressure. CO2 mass flow rate has no obvious impact on entransy dissipation.