Air-conditioning apparatus with low outside air temperature mode

Patent metadata

Field	Value
Publication number	US-9810464-B2
Application number	US-201214379830-A
Country	US
Kind code	B2
Filing date	Apr 27, 2012
Priority date	Apr 27, 2012
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

In a case of a heating operation in which the use side heat exchanger functions as a condenser when an outside temperature is a predetermined low temperature, a low-outside-temperature heating operation start-up mode in which, while a refrigerant discharged from the compressor is caused to flow into the use side heat exchanger, a refrigerant is supplied to the injection port of the compressor via the injection pipe and part of the refrigerant that has transferred heat in the heat source side heat exchanger is supplied to the compressor, is followed by a low-outside-temperature heating operation mode in which the refrigerant discharged from the compressor is supplied to the injection port of the compressor via the injection pipe while the refrigerant being caused to flow into the use side heat exchanger.

First claim

The invention claimed is:

1. An air-conditioning apparatus having a refrigeration cycle in which a compressor, a refrigerant flow switching device, a heat source side heat exchanger, a use side expansion device, and a use side heat exchanger are connected to one another using a refrigerant pipe, the air-conditioning apparatus comprising:
an injection pipe having one side connected to an injection port of the compressor, and another side connected to the refrigerant pipe between the use side expansion device and the heat source side heat exchanger, the injection pipe being configured to inject a refrigerant during a compression operation of the compressor;
a refrigerant heat exchanger configured to exchange heat between the refrigerant flowing through a refrigerant pipe in the refrigeration cycle and the refrigerant flowing through the injection pipe;
a connecting pipe having one side connected to the refrigerant pipe between the refrigerant flow switching device and the use side heat exchanger, and another side connected to a suction side of the compressor, the connecting pipe being configured to direct part of a discharge refrigerant from the compressor to the heat source side heat exchanger and then to cause the part of the discharge refrigerant to flow into the suction side of the compressor;
an opening and closing device disposed in the connecting pipe and capable of switching between opening and closing of a passage in the connecting pipe;
a first temperature sensor configured to detect a temperature on a discharge side of the compressor; and
a controller configured to switch the opening and closing device in accordance with a detection result of the first temperature sensor,
wherein the controller is configured to perform
a low-outside-temperature heating operation start-up mode when an outside temperature is a predetermined low temperature in a case where the detection result of the first temperature sensor is greater than or equal to a preset first predetermined value, and
a low-outside-temperature heating operation mode after performing the low-outside-temperature heating operation start-up mode,
wherein during the low-outside-temperature heating operation start-up mode,
the opening and closing device is opened,
a part of the refrigerant discharged from the compressor flows into the use side heat exchanger,
a part of the refrigerant flowing out from the use side heat exchanger flows into the injection port of the compressor via the injection pipe,
a rest of the refrigerant discharged from the compressor flows into a suction side of the compressor via the connecting pipe, and

wherein during the low-outside-temperature heating operation mode,
the opening and closing device is closed,
the refrigerant discharged from the compressor flows into the use side heat exchanger,
the part of the refrigerant flowing out from the use side heat exchanger flows into the injection port of the compressor via the injection pipe.

2. The air-conditioning apparatus of claim 1 , further comprising:
an outdoor unit including at least the compressor and the heat source side heat exchanger;
an indoor unit including at least the use side heat exchanger;
a second temperature sensor configured to detect an ambient air temperature of the outdoor unit;
a third temperature sensor configured to detect a suction air temperature of the indoor unit; and
a pressure sensor configured to detect a refrigerant pressure on the discharge side of the compressor, wherein
the controller is configured to perform the low-outside-temperature heating operation start-up mode
when (a) the outside temperature is the predetermined low temperature
in a case where (b) the detection result of the first temperature sensor is greater than or equal to the preset first predetermined value,
(c) a detection result of the second temperature sensor is less than or equal to a preset second predetermined value and
(d) a refrigerant saturation temperature calculated from a detection result of the pressure sensor is lower than a detection result of the third temperature sensor.

3. The air-conditioning apparatus of claim 2 , wherein
the controller
closes the opening and closing device, and transitions from the low-outside-temperature heating operation start-up mode to the low-outside-temperature heating operation mode
in a case where the detection result of the second temperature sensor is greater than the preset second predetermined value
or
in a case where the detection result of the second temperature sensor is less than or equal to the preset second predetermined value and the refrigerant saturation temperature calculated from the detection result of the pressure sensor is higher than the detection result of the third temperature sensor.

4. The air-conditioning apparatus of claim 1 , wherein
the controller
controls an opening degree of the opening and closing device to adjust a refrigerant flow rate of refrigerant flowing in the connecting pipe so that the detection result of the first temperature sensor to be higher than a saturation temperature of the discharge refrigerant of the compressor by a third predetermined value or more.

5. The air-conditioning apparatus of claim 4 , wherein
a capacity of the opening and closing device, an inside diameter of the connecting pipe, and a length of the connecting pipe are determined so that
a sum of a drop in refrigerant pressure caused by a flow of refrigerant having the refrigerant flow rate through the opening and closing device and a drop in refrigerant pressure caused by a flow of refrigerant having the refrigerant flow rate through the connecting pipe is equal to a pressure difference that is a difference between a refrigerant pressure on the discharge side of the compressor and a refrigerant pressure on a suction side of the compressor or a refrigerant pressure inside the injection port.

6. The air-conditioning apparatus of claim 5 , wherein
in a case where the third predetermined value is 10 degrees C.,
when a capacity of the opening and closing device, which is calculated from the pressure difference and the refrigerant flow rate, is denoted by a Cv value, and a total amount of refrigerant that flows out of the discharge side of the compressor is denoted by a displacement,
the Cv value is less than or equal to 0.01 when the displacement is 15 m 3 /h or more and less than 30 m 3 /h,
the Cv value is less than or equal to 0.02 when the displacement is 30 m 3 /h or more and less than 40 m 3 /h, and
the Cv value is less than or equal to 0.03 when the displacement is 40 m 3 /h or more and less than 60 m 3 /h.

7. The air-conditioning apparatus of claim 1 , wherein
the refrigerant that circulates in the refrigeration cycle is
HFO1234yf, HFO1234ze(E), R32, HC, a refrigerant mixture of R32 and HFO1234yf, or a refrigerant mixture including at least one of the named refrigerants.

Assignees

• Hatomura Takeshi
• Yamashita Koji
• Takenaka Naofumi
• Mitsubishi Electric Corp

Inventors

• Hatomura Takeshi
• Yamashita Koji
• Takenaka Naofumi

Classifications

• F25B13/00 Primary

  Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02) · CPC title

• F25B40/00

  Subcoolers, desuperheaters or superheaters · CPC title

• F25B2700/2104

  of an indoor room or compartment · CPC title

• F25B2700/2103

  near a heat exchanger · CPC title

• F25B2700/1931

  Discharge pressures · CPC title