The refrigeration system of a Chongqing refrigerated truck consists of a compressor, condenser, expansion valve, and evaporator. Its operation is as follows: The refrigerant boils at a pressure temperature lower than the temperature of the object or fluid being cooled. The compressor continuously draws in the vapor produced in the evaporator and compresses it to the condensing pressure, then sends it to the condenser. Under pressure, it isobarically cooled and condenses into a liquid. The heat released during cooling and condensation is transferred to the cooling medium (usually air used in refrigerated trucks). The condensing temperature, corresponding to the condensing pressure, is higher than the temperature of the cooling medium. The condensed liquid enters the evaporator through the expansion valve or other throttling elements.

Throughout the cycle, the compressor acts as the heart of the system, compressing and transporting the refrigerant vapor and creating a low pressure in the evaporator and a high pressure in the condenser. The expansion valve throttles and reduces the pressure of the refrigerant and regulates the flow rate into the evaporator. The evaporator is the device that outputs cooling capacity; the refrigerant absorbs heat from the object being cooled in the evaporator, thus achieving the purpose of producing cooling. The condenser is the device that outputs heat; the heat absorbed from the evaporator, along with the heat converted from the work consumed by the compressor, is carried away by the cooling medium in the condenser.