Air-conditioning apparatus with a plurality of indoor units and a cooling and heating mixed mode of operation

Patent metadata

Field	Value
Publication number	US-10094604-B2
Application number	US-201314443147-A
Country	US
Kind code	B2
Filing date	Dec 2, 2013
Priority date	Dec 20, 2012
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

An air-conditioning apparatus cools and heats a first heat transfer medium at the same time in a relay unit, and the cooled first heat transfer medium and the heated first heat transfer medium are separately distributed to a plurality of indoor units.

First claim

The invention claimed is:

1. An air-conditioning apparatus comprising:
a plurality of indoor units, wherein each indoor unit is configured to be installed inside a building at a position that allows the indoor units to condition air in a space to be air-conditioned and including a use-side heat exchanger;
a relay unit configured to be installed in a space not to be air-conditioned and different from the space to be air-conditioned; and
an outdoor unit configured to be installed in one of an outdoor space outside the building and a space inside the building communicating with the outdoor space,
wherein the relay unit and the plurality of indoor units are connected to each other via a first heat transfer medium pipe in which a first heat transfer medium that transports heating energy or cooling energy flows,
the outdoor unit and the relay unit are connected to each other via a second heat transfer medium pipe in which a second heat transfer medium that transports heating energy or cooling energy flows,
the relay unit includes:
a first compressor;
a first refrigerant flow switching device;
a plurality of first intermediate heat exchangers;
a second refrigerant flow switching device associated with each of the plurality of first intermediate heat exchangers;
a plurality of first expansion devices that depressurize a first refrigerant that shifts between two phases or turns into a supercritical state during operation; and
a second intermediate heat exchanger, wherein
the first compressor, the first refrigerant flow switching device, a refrigerant flow path in the plurality of first intermediate heat exchangers, the second refrigerant flow switching device, the plurality of first expansion devices, and a refrigerant flow path in the second intermediate heat exchanger are connected via a first refrigerant pipe in which the first refrigerant that shifts between two phases or turns into a supercritical state flows, to form a first refrigerant circuit,
the first heat transfer medium is allowed to circulate through a heat transfer medium flow path in the plurality of first intermediate heat exchangers, a plurality of first heat transfer medium feeding devices that feed the first heat transfer medium, and the plurality of use-side heat exchangers, to form a first heat transfer medium circuit,
cooling of the first heat transfer medium and heating of the first heat transfer medium are performed at the same time utilizing at least one of the first refrigerant flow switching device and the second refrigerant flow switching device,
a first heat transfer medium flow switching device is provided between the plurality of first intermediate heat exchangers and the plurality of use-side heat exchangers,
the first heat transfer medium flow switching device is configured to separately distribute the heated first heat transfer medium and the cooled first heat transfer medium to at least one of the indoor units, and
the outdoor unit is configured to control a temperature of the second heat transfer medium,
the air-conditioning apparatus further comprising a cooling and heating mixed operation mode in which, in the relay unit, heat is removed from or rejected to the second heat transfer medium utilizing evaporation heat or condensation heat of the first refrigerant, the first heat transfer medium is cooled with the evaporation heat of the first refrigerant in at least one of the plurality of first intermediate heat exchangers, and the first heat transfer medium is heated with the condensation heat of the first refrigerant in at least one of the rest of first intermediate heat exchangers,
wherein both of a frequency of the first compressor and a flow rate of the second heat transfer medium flowing into the second intermediate heat exchanger are controlled in the cooling and heating mixed operation mode to:
cause both of the evaporation temperature of the first refrigerant flowing in the refrigerant flow path for cooling the first heat transfer medium in the first intermediate heat exchanger and the condensation temperature of the first refrigerant flowing in the refrigerant flow path for heating the first heat transfer medium in the first intermediate heat exchanger to approach respective target values, or
cause both of a temperature of the first heat transfer medium cooled in the first intermediate heat exchanger cooling the first heat transfer medium and a temperature of the first heat transfer medium heated in the first intermediate heat exchanger heating the first heat transfer medium to approach respective target values.

2. The air-conditioning apparatus of claim 1 , wherein
a temperature of the first heat transfer medium heated by the first intermediate heat exchanger heating the first heat transfer medium is higher than a temperature of the second heat transfer medium, and
a temperature of the first heat transfer medium cooled by the first intermediate heat exchanger cooling the first heat transfer medium is lower than a temperature of the second heat transfer medium.

3. The air-conditioning apparatus of claim 2 , wherein the temperature of the second heat transfer medium is not lower than 10 degrees Celsius and not higher than 40 degrees Celsius.

4. The air-conditioning apparatus of claim 1 , wherein
the relay unit and the plurality of indoor units are connected to each other via a pair of the first heat transfer medium pipes,
the relay unit is connected via a pair of the second heat transfer medium pipes, and
waste heat of the first refrigerant circuit is discharged to the outdoor space via the second heat transfer medium, through heat exchange in the second intermediate heat exchanger between the first refrigerant and the second heat transfer medium.

5. The air-conditioning apparatus of claim 1 , further comprising:
a second heat transfer medium circuit formed by connecting, via a second heat transfer medium pipe in which the second heat transfer medium flows, a heat transfer medium flow path in the second intermediate heat exchanger, a heat transfer medium flow path in a third intermediate heat exchanger, and a second heat transfer medium feeding device connected; and
a second refrigerant circuit formed by connecting, via a second refrigerant pipe in which the second refrigerant flows, a second compressor, a third refrigerant flow switching device, a refrigerant flow path in the third intermediate heat exchanger, a second expansion device that depressurizes a second refrigerant that shifts between two phases or turns into a supercritical state during operation, and a heat source-side heat exchanger, wherein
the second compressor, the third refrigerant flow switching device, the third intermediate heat exchanger, the second expansion device, and the heat source-side heat exchanger are accommodated in the outdoor unit,
the first compressor, the first refrigerant flow switching device, the second refrigerant flow switching device, the plurality of first intermediate heat exchangers, the plurality of first expansion devices, the second intermediate heat exchanger, the plurality of first heat transfer medium feeding devices, and the plurality of first heat transfer medium flow switching devices are accommodated in the relay unit,
the use-side heat exchanger is accommodated in the plurality of indoor units,
the first heat transfer medium circuit and the second heat transfer medium circuit are formed to restrict the first heat transfer medium and the second heat transfer medium from being mixed with each other,
the relay unit includes a first controller, and
the first controller controls, in the cooling and heating mixed operation mode, both of the frequency of the first compressor and the flow rate of the second heat transfer medium flowing into the second intermediate heat exchanger, to cause the evapor

Assignees

• Mitsubishi Electric Corp

Inventors

• Yamashita Koji

Classifications

• F25B7/00

  Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit (F25B9/00 takes precedence) · CPC title

• F25B2313/005

  Outdoor unit expansion valves · CPC title

• F25B2700/21151

  at the suction side of the compressor · CPC title

• F25B49/02 Primary

  for compression type machines, plants or systems · CPC title

• F25B2313/0314

  Temperature sensors near the indoor heat exchanger · CPC title