Air-conditioning apparatus and heat-medium flow-rate calculation method

An air-conditioning apparatus comprising:

• a heat-source-side device configured to heat or cool a heat medium serving as a medium that transfers heat;
• a pump configured to suck the heat medium and transfer the heat medium;
• a plurality of use-side heat exchangers each configured to cause heat exchange to be performed between the heat medium transferred by the pump and indoor air to be conditioned;
• a heat medium circuit that includes a common pipe at which the heat-source-side device and the pump are provided, and parallel pipes that branch off from the common pipe and that are pipes at each of which an associated one of the plurality of use-side heat exchangers is provided, the heat medium circuit being provided such that the common pipe and the parallel pipes are connected, whereby the heat medium circulates;
• a plurality of flow rate control devices provided in association with the use-side heat exchangers and at least upstream or downstream of the use-side heat exchangers, the plurality of flow rate control devices being configured to control flow rates of the heat medium that passes through the use-side heat exchangers;
• a plurality of indoor-side pressure sensors each configured to detect a pressure of the heat medium at least on a heat-medium inflow side or a heat-medium outflow side of an associated one of the flow rate control devices;
• at least one of a pump inlet-side pressure sensor configured to detect a pressure of the heat medium on a suction side of the pump and a pump outlet-side pressure sensor configured to detect a pressure of the heat medium on a transferring side of the pump;
• a flow rate detection device configured to detect a pump flow rate that is a flow rate of the heat medium that flows in the pump;
• and
• a controller configured to control components included in the heat medium circuit,
• wherein the controller is configured to:
• perform a first operation in which the heat medium circuit is caused to circulate the heat medium, the flow rate control devices are individually opened or closed in a predetermined pattern, and data regarding flow rates and pressures of the heat medium that flows through the respective use-side heat exchangers is obtained, and a second operation in which after the first operation, the heat medium is caused to pass through the use-side heat exchangers that supply heat to the indoor air, and
• calculate flow rates of the heat medium that flows through the respective use-side heat exchangers in the second operation, from pump flow rates and pressures in the first operation and the second operation, the pressures being detected by the indoor-side pressure sensors associated with the respective flow rate control devices and the pump inlet-side pressure sensor or the pump outlet-side pressure sensor.