Patent ID: 8418489

Claim:
A refrigeration system, comprising: a refrigerant circuit that, in order to perform a vapor compression supercritical refrigeration cycle, includes a compression mechanism, a heat source side heat exchanger, an expansion mechanism, and a utilization side heat exchanger, wherein the expansion mechanism includes, for two-stage compression of refrigerant in the refrigerant circuit, a high pressure side throttle mechanism variable in the amount of throttling and a low pressure side throttle mechanism variable in the amount of throttling; and a high pressure controller configured to for each temperature of a medium exchanging heat with refrigerant in either the heat source side heat exchanger or the utilization side heat exchanger, whichever becomes a heat dissipation side heat exchanger functioning as a heat dissipation unit, at the inlet of the heat dissipation side heat exchanger, store a relationship between the temperature of refrigerant at the outlet of the heat dissipation side heat exchanger and the pressure of high pressure refrigerant in the refrigerant circuit, for each temperature of the medium at the inlet of the heat dissipation side heat exchanger, store a relationship between a COP and the temperature of refrigerant at the outlet of the heat dissipation side heat exchanger and a relationship between the COP and the pressure of the high pressure refrigerant in the refrigerant circuit, and derive a target value, providing a maximum COP, for the pressure of high pressure refrigerant in the refrigerant circuit based on i) the temperature of refrigerant at the outlet of the heat dissipation side heat exchanger and ii) the temperature of the medium at the inlet of the heat dissipation side heat exchanger, and the high pressure controller further configured to adjust the amount of throttling of the expansion mechanism so that the high pressure refrigerant pressure is controlled to the derived target value.