Refrigerating air conditioning system, method of controlling operation of refrigerating air conditioning system, and method of controlling amount of refrigerant in refrigerating air conditioning system

摘要

In a refrigerating air conditioning system using refrigerant such as CO₂ used in a supercritical area, a highly efficient refrigerating air conditioning system is provided by adjusting the amount of refrigerant in a radiator which contributes to the efficiency of the system stably and quickly. During heat utilizing operation, the superheat at the exit of an evaporator is controlled to a predetermined value by controlling the opening of an expansion valve provided on the upstream side of the evaporator, and an expansion valve is controlled so that the state of refrigerant in a connection pipe on the high-pressure side becomes a supercritical state. In this state, a flow rate control valve is controlled to change the density of the refrigerant stored in a refrigerant storage container and the amount of refrigerant existing in the radiator is adjusted. A target high-pressure value and a target value of the radiator exit temperature are set and the capacity of the compressor is controlled to obtain the target values, and the amount of refrigerant existing in the radiator is adjusted by the refrigerant amount adjusting circuit.