AIR-CONDITIONING APPARATUS

• US 20140182329A1
• Filed: 11/07/2011
• Published: 07/03/2014
• Est. Priority Date: 11/07/2011
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Yamashita, Koji, Hatomura, Takeshi, Ishimura, Katsuhiro
• Granted Patent: US 9,797,610 B2
• Time in Patent Office: Days
• US Class Current: 62/498
• CPC Class Codes: F24F 5/001 Compression cycle type
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2313/003 Indoor unit with water as a heat sink or heat source
• CPC Class Codes: F25B 2313/0231 with simultaneous cooling and heating
• CPC Class Codes: F25B 2313/02732 using two three-way valves
• CPC Class Codes: F25B 2313/02741 using one four-way valve
• CPC Class Codes: F25B 2313/0312 Pressure sensors near the indoor heat exchanger
• CPC Class Codes: F25B 2313/0314 Temperature sensors near the indoor heat exchanger
• CPC Class Codes: F25B 2313/0315 Temperature sensors near the outdoor heat exchanger
• CPC Class Codes: F25B 25/005 using primary and secondary systems
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2500/26 characterised by the startup of the refrigeration cycle
• CPC Class Codes: F25B 2600/2513 Expansion valves
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/1933 Suction pressures
• CPC Class Codes: F25B 2700/21151 at the suction side of the compressor
• CPC Class Codes: F25B 2700/21152 at the discharge side of the compressor
• CPC Class Codes: F25B 2700/21161 of the fluid heated by the condenser
• CPC Class Codes: F25B 2700/21162 of the refrigerant at the inlet of the condenser
• CPC Class Codes: F25B 2700/21163 of the refrigerant at the outlet of the condenser
• CPC Class Codes: F25B 2700/21173 : at the outlet
• CPC Class Codes: F25B 2700/21174 : of the refrigerant at the inlet of the evaporator
• CPC Class Codes: F25B 2700/21175 : of the refrigerant at the outlet of the evaporator
• CPC Class Codes: F25B 31/008 : by injecting a liquid
• CPC Class Codes: F25B 41/20 : Disposition of valves, e.g. of on-off valves or flow control valves expansion valves F25B41/31
• CPC Class Codes: F25B 41/24 : Arrangement of shut-off valves for disconnecting a part of the refrigerant cycle, e.g. an outdoor part

Abstract

An air-conditioning apparatus includes a suction-injection pipe that introduces a refrigerant in a liquid or two-phase state into a suction side of a compressor, an expansion device that is arranged at the suction-injection pipe, and a controller that regulates the suction-injection flow rate of a refrigerant introduced into the suction side of the compressor through the suction-injection pipe by controlling the opening degree of the expansion device.

Claims

1. An air-conditioning apparatus having a refrigeration cycle including a compressor, a first heat exchanger, a first expansion device, and second heat exchangers that are connected by pipes, the air-conditioning apparatus comprising:

a suction-injection pipe configured to introduce, into a suction side of the compressor, a refrigerant in a liquid or two-phase state that is branched from a refrigerant flow passage through which the refrigerant that transfers heat in the first heat exchanger or the second heat exchangers circulates;

a second expansion device arranged at the suction-injection pipe; and

a controller configured to regulate, by controlling an opening degree of the second expansion device, a suction-injection flow rate of the refrigerant introduced into the suction side of the compressor through the suction-injection pipe.

2. The air-conditioning apparatus of claim 1, further comprising:

a refrigerant flow switching device configured to perform switching of the refrigerant flow passage, depending on whether a high-pressure refrigerant is flowed in the first heat exchanger so that the first heat exchanger functions as a condenser or a low-pressure refrigerant is flowed in the first heat exchanger so that the first heat exchanger functions as an evaporator; and

a third expansion device configured to generate, in a case where the first heat exchanger functions as an evaporator, medium pressure that is lower than high pressure, which is pressure inside the second heat exchangers functioning as a condenser and that is higher than low pressure, which is pressure inside the first heat exchanger functioning as the evaporator,

wherein the controller allows

in a case where the first heat exchanger functions as a condenser, a high-pressure refrigerant to flow through the suction-injection pipe, and

in the case where the first heat exchanger functions as an evaporator, a medium pressure refrigerant generated by the third expansion device to flow through the suction-injection pipe.

3. The air-conditioning apparatus of claim 2,

wherein in the case where the first heat exchanger functions as a condenser, the refrigerant is caused to circulate between the first heat exchanger and the second heat exchangers without causing the refrigerant to pass through the third expansion device, and

wherein in the case where the first heat exchanger functions as an evaporator, the refrigerant is caused to pass through the second heat exchangers and then the third expansion device and to flow into the first heat exchanger.

4. The air-conditioning apparatus of claim 1, further comprising:

a first branching unit configured to branch a refrigerant from the refrigerant flow passage in a case where the refrigerant flows from the first heat exchanger to the first expansion device;

a second branching unit configured to branch a refrigerant from the refrigerant flow passage in a case where the refrigerant flows from the first expansion device to the first heat exchanger;

a branch pipe configured to connect the first branching unit with the second branching unit and connected thereof the suction-injection pipe;

a first conduction device arranged between the first branching unit and a connection portion of the branch pipe and the suction-injection pipe; and

a second conduction device arranged between the second branching unit and the connection portion of the branch pipe and the suction-injection pipe.

5. The air-conditioning apparatus of claim 4,

wherein the first conduction device is an opening/closing device configured to open and close the refrigerant flow passage of the branch pipe, and

wherein the second conduction device is a backflow prevention device configured to flow a refrigerant only in a direction from the second branching unit to the suction injection pipe.

6. The air-conditioning apparatus of claim 4,

wherein the first branching unit is a gas-liquid separator configured to flow mainly a refrigerant in a liquid state to circulate through the branch pipe.

7. The air-conditioning apparatus of claim 4,

wherein the second branching unit is a gas-liquid separator configured to flow mainly a refrigerant in a liquid state to circulate through the branch pipe.

8. The air-conditioning apparatus of claim 6,

wherein the gas-liquid separator has a structure in which

a length in a direction in which the refrigerant flows in is greater than a length in a direction perpendicular to the direction in which the refrigerant flows in,

an inlet pipe from which a refrigerant flows therein and an outlet pipe through which a majority of the flowed refrigerant flows out are connected in parallel to the direction in which the refrigerant flows in, and

the branch pipe is connected to a lower portion that is lower than a central portion in a height direction of the gas-liquid separator, the branch pipe configured to extract part of the refrigerant in the liquid state from inside thereof to outside.

9. The air-conditioning apparatus of claim 4, further comprising:

a discharged refrigerant temperature detection device for detecting temperature of a refrigerant discharged from the compressor,

wherein the controller regulates an opening area of the second expansion device in such a manner that the temperature of the discharged refrigerant detected by the discharged refrigerant temperature detection device becomes closer to a target temperature, does not exceed the target temperature, or falls within a target temperature range.

10. The air-conditioning apparatus of claim 4, further comprising:

a discharged refrigerant temperature detection device for detecting temperature of a refrigerant discharged from the compressor; and

high-pressure detection device for detecting pressure of the refrigerant discharged from the compressor,

wherein the controller regulates an opening area of the second expansion device in such a manner that a discharge degree of superheat calculated from the temperature of the discharged refrigerant detected by the discharged refrigerant temperature detection device and the refrigerant pressure detected by the high-pressure detection device becomes closer to a target degree of superheat, does not exceed the target degree of superheat, or falls within a target degree range of superheat.

11. The air-conditioning apparatus of claim 4, further comprising:

a medium pressure detection device for detecting medium pressure or saturation temperature at the medium pressure, the medium pressure detection device being arranged at the refrigerant flow passage between the second branching unit and the third expansion device,

wherein in a state in which the first heat exchanger functions as an evaporator,

the controller regulates an opening area of the third expansion device in such a manner that the medium pressure or the saturation temperature at the medium pressure detected by the medium pressure detection device becomes closer to a target value or falls within a target range.

12. The air-conditioning apparatus of claim 4,

wherein a refrigerant-refrigerant heat exchanger is arranged at a portion of the suction-injection pipe that is positioned between the connection portion of the branch pipe and the suction-injection pipe and the second expansion device, and

wherein the refrigerant-refrigerant heat exchanger exchanges heat between the refrigerant that has flowed in from the connection portion and the refrigerant that has flowed out of the second expansion device.

13. The air-conditioning apparatus of claim 2,

wherein the third expansion device includes, at a portion of a flow passage that is on an entry side of an expansion part and that is near the expansion part, a mixing device configured to mix a two-phase gas-liquid refrigerant that has flowed into the third expansion device.

14. The air-conditioning apparatus of claim 1,

wherein the second expansion device includes, at a portion of a flow passage that is on an entry side of an expansion part and that is near the expansion part, a mixing device configured to mix a two-phase gas-liquid refrigerant that has flowed into the second expansion device.

15. The air-conditioning apparatus of claim 4, further comprising:

an outdoor unit accommodating the compressor, the refrigerant flow switching device, the first heat exchanger, the second expansion device, the suction-injection pipe, the branch pipe, the first branching unit, the second branching unit, the first conduction device, and the second conduction device;

an indoor unit accommodating a use-side heat exchanger configured to exchange heat with air in an air-conditioned space and arranged at a position from which the air-conditioned space can be air-conditioned; and

a heat medium relay unit accommodating the second heat exchangers and the first expansion device, the heat medium relay unit being configured independent of the outdoor unit and the indoor unit,

wherein two refrigerant pipes through which a refrigerant circulates connect between the outdoor unit and the heat medium relay unit,

wherein two heat medium pipes through which a heat medium circulates connect between the heat medium relay unit and the indoor unit,

wherein the second heat exchangers exchange heat between the refrigerant and the heat medium, and

wherein the use-side heat exchanger exchanges heat between the air in the air-conditioned space and the heat medium.

16. The air-conditioning apparatus of claim 4, further comprising:

an outdoor unit accommodating the compressor, the refrigerant flow switching device, the first heat exchanger, the second expansion device, the suction-injection pipe, the branch pipe, the first branching unit, the second branching unit, the first conduction device, and the second conduction device;

an indoor unit accommodating the second heat exchanger and the first expansion device and arranged at a position from which an air-conditioned space can be air-conditioned; and

a relay unit configured to be independent of the outdoor unit and the indoor unit,

wherein two refrigerant pipes connect between the outdoor unit and the relay unit and between the relay unit and the indoor unit,

wherein the refrigerant circulates, via the relay unit, between the outdoor unit and the indoor unit, and

wherein the second heat exchanger exchanges heat between the refrigerant and the air in the air-conditioned space.

17. The air-conditioning apparatus of claim 15,

wherein the controller is capable of selectively executing

a cooling only operation mode, in which the first heat exchanger operates as a condenser, all of the second heat exchangers operate as an evaporator, a high-pressure liquid refrigerant flows in one of the two refrigerant pipes, and a low-pressure gas refrigerant flows in the other one of the two refrigerant pipes, and

a heating only operation mode, in which the first heat exchanger operates as an evaporator, all of the second heat exchangers operate as a condenser, a high-pressure gas refrigerant flows in one of the two refrigerant pipes, and a medium pressure, two-phase gas-liquid refrigerant or a medium pressure liquid refrigerant flows in the other one of the two refrigerant pipes.

18. The air-conditioning apparatus of claim 15,

wherein the controller is capable of selectively executing

a cooling main operation mode, in which the first heat exchanger operates as a condenser, part of the second heat exchangers operate as an evaporator, the rest of the second heat exchangers operate as a condenser, a high-pressure, two-phase gas-liquid refrigerant flows in one of the two refrigerant pipes, and a low-pressure gas refrigerant flows in the other one of the two refrigerant pipes, and

a heating main operation mode, in which the first heat exchanger operates as an evaporator, part of the second heat exchangers operate as a condenser, the rest of the second heat exchangers operate as an evaporator, a high-pressure gas refrigerant flows in one of the two refrigerant pipes, and a medium pressure, two-phase gas-liquid refrigerant flows in the other one of the two refrigerant pipes.

19. The air-conditioning apparatus of claim 1,

wherein a refrigerant used in the refrigeration cycle is R32, a mixed refrigerant containing R32 having a mass ratio of 62% or higher and HFO1234yf, or a mixed refrigerant containing R32 having a mass ratio of 43% or higher and HFO1234ze.