Patent ID: 11906191
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F  Y | IPC F

Claim 8:
9. An air-conditioning apparatus comprising:
a primary-side circuit in which a compressor that compresses refrigerant, a first flow switching device that switches a circulation path of the refrigerant, an outdoor heat exchanger that exchanges heat between the refrigerant and a heat-source-side fluid, a second flow switching device that switches the circulation path of the refrigerant, a first expansion device and a second expansion device each of which is disposed at a pipe between the first flow switching device and the second flow switching device and adjust a pressure of the refrigerant, and a first relay heat exchanger and a second relay heat exchanger that exchange heat between the refrigerant and a heat medium different from the refrigerant are connected by pipes and in which the refrigerant circulates;
a secondary-side circuit in which the first relay heat exchanger, the second relay heat exchanger, a first pump and a second pump that pressurize the heat medium, a plurality of indoor heat exchangers, each of which exchanges heat between the heat medium and air for an air-conditioning target space, heat medium flow control devices, each of which is installed in such a manner as to correspond to an indoor heat exchanger among the indoor heat exchangers and adjusts a flow rate of the heat medium passing through the indoor heat exchanger, heat medium flow switching devices, each of which is installed between the first relay heat exchanger and an indoor heat exchanger among the indoor heat exchangers and switches a circulation path of the heat medium, and heat medium flow switching devices, each of which is installed between the second relay heat exchanger and an indoor heat exchanger among the indoor heat exchangers and switches the circulation path of the heat medium, are connected by pipes and in which the heat medium circulates; and
a refrigerant-refrigerant heat exchanger disposed at a pipe connecting between the second flow switching device and the first expansion device,
a bypass circuit including
a bypass pipe having one end connected to a pipe between the refrigerant-refrigerant heat exchanger and the first expansion device and an other end connected to a pipe between the second flow switching device and the compressor and
a bypass expansion device that adjusts flow rate of the refrigerant passing through the bypass pipe,

a controller configured to control the first flow switching device and the second flow switching device to provide the circulation path of the refrigerant such that in a cooling operation, a heating operation, and a cooling and heating simultaneous operation, the refrigerant and the heat-source-side fluid flow through the outdoor heat exchanger in opposite directions, and the refrigerant flows through the first relay heat exchanger and the second relay heat exchanger in a constant direction,
wherein the first pump and the second pump are installed such that the heat medium flows through the first relay heat exchanger and the second relay heat exchanger in a direction opposite to the direction in which the refrigerant flows, and
the refrigerant-refrigerant heat exchanger
is disposed such that
the refrigerant passing through the refrigerant-refrigerant heat exchanger and flowing between the second flow switching device and the first expansion device and
the refrigerant passing through the refrigerant-refrigerant heat exchanger and flowing through the bypass circuit
flow in opposite directions, and

exchanges, in the refrigerant-refrigerant heat exchanger, heat between
high-pressure two-phase refrigerant or liquid refrigerant flowing between the second flow switching device and the first expansion device and
low-pressure two-phase refrigerant flowing through the bypass circuit having the bypass pipe

in any of cooling and the heating operations.