An air-conditioning apparatus comprising:
- a plurality of heat source apparatuses each including a compressor, an outdoor side expansion valve, a heat source side heat exchanger, and an accumulator;
- a plurality of indoor units each including an indoor heat exchanger and each configured to perform one of a cooling operation and a heating operation;
- a relay device connected to the heat source apparatuses by a high pressure pipe and a low pressure pipe and configured to distribute refrigerant flowing therein from the heat source apparatuses to the plurality of indoor units;
- and
- a controller configured to control operations of the heat source apparatuses, wherein:
- the relay device includes
- a gas-liquid separator configured to separate the refrigerant flowing from the high pressure pipe into gas refrigerant in a gas state and liquid refrigerant in a liquid state;
- a gas pipe configured to supply the gas refrigerant exiting the gas-liquid separator to any indoor unit performing the heating operation from among the plurality of indoor units during a heating main operation in which one or more of the plurality of indoor units perform the cooling operation, whereas remaining indoor units perform the heating operation;
- a liquid pipe configured to supply the liquid refrigerant flowing from the gas-liquid separator to the one or more indoor units performing the cooling operation from among the plurality of indoor units during the heating main operation;
- a bypass pipe branching off from the liquid pipe and connected to the low pressure pipe;
- a bypass flow control valve configured to regulate a flow volume of the refrigerant flowing through the bypass pipe;
- and
- a relay device temperature detecting sensor configured to detect a temperature of the refrigerant flowing through the bypass pipe,
- the plurality of heat source apparatuses include a first heat source apparatus including a first outdoor expansion valve and a second heat source apparatus including a second outdoor expansion valve,
- an opening degree of the first outdoor side expansion valve prior to change of the opening degree is LEV2a*,
- an opening degree of the second outdoor side expansion valve prior to change of the opening degree is LEV2b*,
- an opening degree of the first outdoor side expansion valve after a first opening degree change amount is added to LEV2a* is LEV2a,
- an opening degree of the second outdoor side expansion valve after a second opening degree change amount is added to LEV2b* is LEV2b,
- during the heating main operation, the controller
- sets an opening degree change amount of each of the outdoor side expansion valves based on a superheat degree of the compressor of each heat source apparatus, the superheat degree being calculated using a pressure and temperature of refrigerant detected by a pressure detecting sensor and a temperature detecting sensor, respectively, that are disposed on one of a discharge side and a suction of side of the compressor of each heat source apparatus, and
- increases or decreases a sum of opening degrees of the outdoor side expansion valves of the plurality of heat source apparatuses by changing opening degrees of the outdoor expansion valves while maintaining a ratio between opening degree change amounts of the outdoor side expansion valves in response to the temperature detected by the relay device temperature detecting sensor, and
- when a temperature T5 detected by the relay device temperature detecting sensor is lower than a target value T5m, while a sum (LEV2a+LEV2b) of the values obtained by adding each of the opening degree change amounts to the respective opening degree prior to change of the first and second outdoor side expansion valves of the heat source apparatuses is larger than a sum (LEV2a*+LEV2b*) of the opening degrees prior to change of the first and second outdoor side expansion valves of the heat source apparatuses,
- the controller determines a correction coefficient α satisfying a condition 0<α<(LEV2a*+LEV2b*)/(LEV2a+LEV2b), and
- the controller changes the opening degree of the first and second outdoor side expansion valves by a value obtained by multiplying the corresponding one of the opening degree change amounts (ΔLEV2a, ΔLEV2b) by the correction coefficient α.