Refrigeration system

A refrigeration system comprising:

• a refrigerant circuit including a compressor,
• a heat-source heat exchanger connected to a discharge side of the compressor at one end thereof,
• a liquid pipe connected to the other end of the heat-source heat exchanger through a heat-source expansion valve,
• a plurality of heat exchangers connected in parallel to the liquid pipe at one ends thereof,
• a plurality of expansion valves, each of which is provided on one end of the corresponding heat exchanger to adjust an amount of a refrigerant flowing to the corresponding heat exchanger, and
• a switching mechanism which switches a flow path of the refrigerant so that the other ends of the heat exchangers are connected to one of a suction side and a discharge side of the compressor, wherein
• the refrigeration circuit includes a high-pressure-side pressure difference detection unit which detects an index of pressure difference between a high pressure refrigerant on the discharge side of the compressor and a refrigerant in the liquid pipe in concurrent operation of performing a refrigeration cycle in which the heat-source heat exchanger functions as a condenser, and simultaneously, at least one of the plurality of heat exchangers functions as a condenser, and at least one of the plurality of heat exchangers functions as an evaporator,
• an expansion valve control unit which adjusts the degree of opening of the heat-source expansion valve in the concurrent operation so that a value detected by the high-pressure-side pressure difference detection unit becomes larger than a predetermined value, wherein
• the refrigerant circuit includes three or more heat exchangers connected in parallel to the liquid pipe, and a low-pressure-side pressure difference detection unit which detects an index of pressure difference between the refrigerant in the liquid pipe and a low pressure refrigerant on the suction side of the compressor,
• the expansion valve control unit adjusts the degree of opening of the heat-source expansion valve so that a value detected by the high-pressure-side pressure difference detection unit becomes larger than a predetermined value, and a value detected by the low-pressure-side pressure difference detection unit becomes larger than a predetermined value, in the concurrent operation of performing a refrigeration cycle in which the heat-source heat exchanger functions as a condenser, and simultaneously, at least two of the plurality of heat exchangers function as evaporators, and at least one of the plurality of heat exchangers functions as a condenser,
• the low-pressure-side pressure difference detection unit includes an on-liquid-pipe pressure sensor provided on the liquid pipe, and a low-pressure-side pressure sensor provided on the suction side of the compressor, and
• the low-pressure-side pressure difference detection unit is configured to detect difference between pressure detected by the on-liquid-pipe pressure sensor and pressure detected by the low-pressure-side pressure sensor as the index of pressure difference between the refrigerant in the liquid pipe and the low pressure refrigerant.

A refrigeration system comprising:

• a refrigerant circuit including a compressor,
• a heat-source heat exchanger connected to a discharge side of the compressor at one end thereof,
• a liquid pipe connected to the other end of the heat-source heat exchanger through a heat-source expansion valve,
• a plurality of heat exchangers connected in parallel to the liquid pipe at one ends thereof,
• a plurality of expansion valves, each of which is provided on one end of the corresponding heat exchanger to adjust an amount of a refrigerant flowing to the corresponding heat exchanger, and
• a switching mechanism which switches a flow path of the refrigerant so that the other ends of the heat exchangers are connected to one of a suction side and a discharge side of the compressor, wherein
• the refrigeration circuit includes a high-pressure-side pressure difference detection unit which detects an index of pressure difference between a high pressure refrigerant on the discharge side of the compressor and a refrigerant in the liquid pipe in concurrent operation of performing a refrigeration cycle in which the heat-source heat exchanger functions as a condenser, and simultaneously, at least one of the plurality of heat exchangers functions as a condenser, and at least one of the plurality of heat exchangers functions as an evaporator,
• an expansion valve control unit which adjusts the degree of opening of the heat-source expansion valve in the concurrent operation so that a value detected by the high-pressure-side pressure difference detection unit becomes larger than a predetermined value, wherein
• the refrigerant circuit includes three or more heat exchangers connected in parallel to the liquid pipe, and a low-pressure-side pressure difference detection unit which detects an index of pressure difference between the refrigerant in the liquid pipe and a low pressure refrigerant on the suction side of the compressor, and
• the expansion valve control unit adjusts the degree of opening of the heat-source expansion valve so that a value detected by the high-pressure-side pressure difference detection unit becomes larger than a predetermined value, and a value detected by the low-pressure-side pressure difference detection unit becomes larger than a predetermined value, in the concurrent operation of performing a refrigeration cycle in which the heat-source heat exchanger functions as a condenser, and simultaneously, at least two of the plurality of heat exchangers function as evaporators, and at least one of the plurality of heat exchangers functions as a condenser,
• the low-pressure-side pressure difference detection unit includes an on-liquid-pipe temperature sensor provided on the liquid pipe, and an evaporation temperature detection unit which detects evaporation temperature of the refrigerant in the heat exchanger serving as an evaporator in the concurrent operation, and
• the low-pressure-side pressure difference detection unit is configured to detect difference between temperature detected by the on-liquid-pipe temperature sensor and temperature detected by the evaporation temperature detection unit as the index of pressure difference between the low pressure refrigerant and the refrigerant in the liquid pipe.