AIR-CONDITIONING APPARATUS

• US 20140331702A1
• Filed: 12/22/2011
• Published: 11/13/2014
• Est. Priority Date: 12/22/2011
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Tanaka, Kosuke, Yamashita, Koji, Hatomura, Takeshi, Wakamoto, Shinichi, Takenaka, Naofumi
• Granted Patent: US 10,018,389 B2
• Time in Patent Office: Days
• US Class Current: 62/159
• CPC Class Codes: F25B 1/10 with multi-stage compression with cascade operation F25B7/00
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• 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 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: F25B 2600/0271 the discharge pressure
• 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 2700/2106 of fresh outdoor air
• 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 2700/21163 of the refrigerant at the outlet of the condenser
• CPC Class Codes: F25B 29/003 of the compression type system
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: F25B 49/027 Condenser control arrangements
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

An air-conditioning apparatus including a refrigeration cycle configured by connecting one or more load-side units including a load-side heat exchanger and a load-side expansion device with a heat-source-side unit including a heat-source-side heat exchanger and a compressor and by causing refrigerant to circulate through a refrigerant circuit including the load-side heat exchanger, the load-side expansion device, the heat-source-side heat exchanger, and the compressor, controls, during a heating operation, the opening degree of the load-side expansion device, based on the discharge pressure of the compressor, so that the pressure of refrigerant at the outlet of the compressor becomes equal to a target pressure, in the case where the operation capacity of the compressor is approximately at the maximum value of the operation capacity of the compressor.

Claims

1. An air-conditioning apparatus including a refrigeration cycle configured by connecting a load-side heat exchanger, a first expansion device, a heat-source-side heat exchanger and a compressor and by causing refrigerant to circulate through a refrigerant circuit including the load-side heat exchanger, the first expansion device, the heat-source-side heat exchanger, and the compressor,

the air-conditioning apparatus comprising a controller configured to control an opening degree of the first expansion device and an operation capacity of the compressor,

wherein the controller, during a heating operation, controls an opening degree of the first expansion device so that a degree of subcooling of the refrigerant at an outlet of the load-side heat exchanger becomes equal to a target degree of subcooling and controls an operation capacity of the compressor so that pressure of the refrigerant at an outlet of the compressor becomes equal to a target pressure, and

in a case where an operation capacity of the compressor is approximately at a maximum value of the operation capacity of the compressor and a condensing temperature of the load-side heat exchanger is lower than a target temperature, the controller controls an opening degree of the first expansion device, based on a discharge pressure of the compressor, so that pressure of the refrigerant at the outlet of the compressor becomes equal to a target pressure.

5. The air-conditioning apparatus of claim 1,

wherein an upper limit value of the target pressure is determined based on an upper limit restriction temperature of a discharge temperature of the compressor or withstand pressures of pipes of the refrigerant circuit.

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

an accumulator that is provided on a suction side of the compressor and that stores the refrigerant.

2. An air-conditioning apparatus including a refrigeration cycle configured by connecting a load-side heat exchanger, a first expansion device, a second expansion device, a heat-source-side heat exchanger, and a compressor and by causing refrigerant to circulate through a refrigerant circuit including the load-side heat exchanger, the first expansion device, the second expansion device, the heat-source-side heat exchanger, and the compressor,

wherein the compressor is a compressor that is capable of injecting refrigerant, and the air-conditioning apparatus comprises

a controller configured to control an opening degree of the first expansion device and an operation capacity of the compressor,

a bypass pipe that extends from a portion of a flow passage between the first expansion device and the second expansion device to an injection port of the compressor, and

a bypass expansion device that adjusts a flow rate of the bypass pipe, and

wherein the controller, during a heating operation, controls an opening degree of the first expansion device so that a degree of subcooling of the refrigerant at an outlet of the load-side heat exchanger becomes equal to a target degree of subcooling and controls the operation capacity of the compressor so that pressure of the refrigerant at the outlet of the compressor becomes equal to a target pressure, and

in a case where an operation capacity of the compressor is approximately at a maximum value of the operation capacity of the compressor and a condensing temperature of the load-side heat exchanger is lower than a target temperature, the controller controls an opening degree of the first expansion device, based on a discharge pressure of the compressor, so that the pressure of the refrigerant at the outlet of the compressor becomes equal to the target pressure.

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

a receiver that is provided between the first expansion device and the second expansion device and that stores refrigerant,

wherein during the heating operation, in a case where a degree of suction refrigerant superheat of the compressor is lower than a target value, the controller reduces an opening degree of the second expansion device so that the degree of suction refrigerant superheat increases.

4. The air-conditioning apparatus of claim 2,

wherein during the heating operation, in a case where the operation capacity of the compressor is approximately at the maximum value of the operation capacity of the compressor and the discharge pressure of the compressor is smaller than a target value, the controller performs control for reducing an air volume of air blown to the load-side heat exchanger, instead of the control for the opening degree of the first expansion device or along with the control for the opening degree of the first expansion device, to achieve the target pressure.

7. The air-conditioning apparatus of claim 2,

wherein an upper limit value of the target pressure is determined based on an upper limit restriction temperature of a discharge temperature of the compressor or withstand pressures of pipes of the refrigerant circuit.

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

an accumulator that is provided on a suction side of the compressor and that stores the refrigerant.