Refrigeration cycle apparatus

A refrigeration cycle apparatus comprising:

• a main refrigerant circuit having a compressor provided with an injection portion, a radiator that heats fluid, a first expansion mechanism, a second expansion mechanism, and an evaporator, which are connected in a circuit in this order;
• an injection passage connecting the injection portion of the compressor to a portion of the main refrigerant circuit between the first expansion mechanism and the second expansion mechanism;
• a fluid circuit through which the fluid, which is heated in the radiator by a refrigerant in the main refrigerant circuit, flows;
• and
• a sub heat exchanger that is a liquid-liquid heat exchanger, which comprises a low-temperature side flow passage and a high-temperature side flow passage, cools the fluid flowing in the high-temperature side flow passage, and heats the refrigerant flowing in the low-temperature side flow passage by exchanging heat between the refrigerant and the fluid before the fluid is heated in the radiator,
• wherein the sub heat exchanger is disposed in the injection passage,
• a flow rate regulator that regulates a flow rate of the refrigerant, which flows from the main refrigerant circuit into the injection passage, into the sub heat exchanger by adjustment of an opening degree of the flow rate regulator, is further disposed in the injection passage, wherein the regulating the flow rate of the refrigerant includes closing an opening for the flow of the refrigerant into the sub heat exchanger, and
• the sub heat exchanger is located between the flow rate regulator and the compressor.