Air-conditioning system

An air-conditioning system, comprising:

• a plurality of indoor units;
• a relay unit including an intermediate heat exchanger configured to exchange heat between refrigerant and a heat medium;
• and
• a heat source unit including a compressor and a heat source-side heat exchanger and configured to supply cooling energy or heating energy to each of the plurality of indoor units via the relay unit,
• wherein the heat source unit and the relay unit are connected by a heat-source connection pipe through which the refrigerant flows,
• wherein the relay unit and the plurality of indoor units are connected by a load connection pipe through which the heat medium flows,
• wherein the load connection pipe comprises a main pipe connecting between the relay unit and one of the indoor units provided at an end of the load connection pipe opposite to the relay unit,
• wherein the main pipe has branch parts associated with the indoor units other than the one of the indoor units provided at the end of the load connection pipe opposite to the relay unit among the plurality of indoor units, and
• wherein a length of the main pipe from a connection part connected to the relay unit to a first branch part, which is closest to the relay unit of the branch parts, is smaller than a length of the heat-source connection pipe,
• wherein the heat source unit comprises the compressor, the heat source-side heat exchanger, and a heat source-side expansion device provided in downstream of the heat source-side heat exchanger during a cooling operation in which the heat source-side heat exchanger functions as a condenser,
• wherein the heat source-side expansion device is configured such that the refrigerant to be caused to flow into the relay unit is brought into a two-phase state during the cooling operation,
• wherein the relay unit comprises a relay unit expansion device provided in downstream of the intermediate heat exchanger during a heating operation in which the intermediate heat exchanger functions as a condenser, and
• wherein the relay unit expansion device is configured such that the refrigerant to be caused to flow into the heat source unit is brought into a two-phase state during the heating operation.