Air-conditioning apparatus

An air-conditioning apparatus comprising:

• a refrigeration cycle circulating refrigerant and connecting a compressor, a heat-source-side heat exchanger, one or more of load-side expansion valves, and one or more of load-side heat exchangers by refrigerant pipes;
• a bypass having one end connected to a discharge side of the compressor of the refrigeration cycle and another end connected to a suction side of the compressor of the refrigeration cycle to bypass a portion of the refrigerant discharged from the compressor;
• a first expansion device disposed in the bypass and comprising a member selected from the group consisting of a variable expansion valve and a fixed expansion device including a pipe or capillary tube, the first expansion device being configured to depressurize the refrigerant flowing through the bypass;
• an auxiliary heat exchanger disposed downstream of the first expansion device of the bypass and cooling the refrigerant which flows into the auxiliary heat exchanger, the auxiliary heat exchanger being configured to send out all the cooled refrigerant to the suction side of the compressor;
• a second expansion device comprising an expansion valve disposed downstream of the auxiliary heat exchanger of the bypass and configured to control a flow rate of the refrigerant flowing from the auxiliary heat exchanger to the suction side of the compressor;
• a third expansion device comprising an expansion valve at least configured to be opened and closed is disposed in parallel with the first expansion device in the bypass, and
• a controller configured to
• control an opening degree of the second expansion device,
• open or close the third expansion device on a basis of a refrigerant circulation volume of the refrigerant discharged from the compressor,
• calculate a density of saturated gas on a basis of a pressure of the refrigerant at the suction side of the compressor,
• calculate the refrigerant circulation volume on a basis of the density of saturated gas and a frequency of the compressor,
• calculate a maximum refrigerant circulation volume on a basis of the density of saturated gas and a maximum operable frequency of the compressor, and
• open the third expansion device when a maximum refrigerant circulation volume ratio determined by dividing the refrigerant circulation volume by the maximum refrigerant circulation volume is a predetermined value or more.