Variable refrigerant flow system operation in low ambient conditions

Patent metadata

Field	Value
Publication number	US-10337780-B2
Application number	US-201514930357-A
Country	US
Kind code	B2
Filing date	Nov 2, 2015
Priority date	Dec 9, 2014
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

A system comprising a compressor coupled to a first coil through a first valve and a second coil through a second valve, wherein the first coil and the second coil are coupled to a third coil. The system further comprises a fan operable to blow ambient air across the first coil, a first expansion valve coupled to and positioned between the first coil and the third coil and a second expansion valve coupled to and positioned between the second coil and the third coil. The system comprises a controller operable to monitor a pressure of the refrigerant, operate the first expansion valve to reduce refrigerant flow into the first, and operate the second expansion valve to reduce refrigerant flow through the second coil.

First claim

The invention claimed is:

1. A system comprising:
a compressor coupled to a first coil through a first valve and a second coil through a second valve, wherein the first coil and the second coil are further coupled to a third coil, the compressor being operable to compress refrigerant and pump the refrigerant out of a first compressor opening into the first and second coils and receive the refrigerant through a second compressor opening after the refrigerant has passed through the third coil;
one or more first fans operable to blow ambient air across the first coil;
one or more second fans operable to blow ambient air across the second coil;
a first expansion valve coupled to and positioned between the first coil and the third coil;
a second expansion valve coupled to and positioned between the second coil and the third coil;
one or more sensors positioned to sense a pressure of the refrigerant circulating through the system; and
a controller operable to trigger a low ambient temperature mode to:
configure the first coil as an active coil by energizing one or more of the first fans;
configure the second coil as an inactive coil by de-energizing the one or more second fans;
monitor the refrigerant pressure based on data received from the one or more sensors;
in response to determining that the refrigerant pressure is below a low threshold pressure:
operate the first expansion valve to reduce refrigerant flow into the first coil and increase refrigerant flow through the second coil and into the third coil;
determine whether the first expansion valve is closed; and
in response to determining that the first expansion valve is closed, shut off the compressor and the one or more first fans; and

in response to determining that the refrigerant pressure is above a high threshold pressure, operate the second expansion valve to reduce refrigerant flow through the second coil and increase refrigerant flow through the first coil and into the third coil.

2. The system of claim 1 , wherein, in response to determining that the refrigerant pressure is above the high threshold pressure, the controller is further operable to increase a speed of at least one of the one or more first fans.

3. The system of claim 1 , wherein the first coil and the second coil are positioned outside a building and the third coil is positioned inside a building.

4. The system of claim 1 , wherein the controller is operable to trigger the low ambient temperature mode in response to determining that an ambient temperature is below a threshold temperature.

5. The system of claim 4 , wherein at least some of the refrigerant condenses as it passes through the first coil and the second coil.

6. The system of claim 4 , wherein at least some of the refrigerant evaporates as it passes through the third coil.

7. An apparatus comprising:
a memory operable to store a threshold temperature, a low threshold pressure, and a high threshold pressure; and
a processor operable to:
configure a first coil as an active coil by energizing one or more fans operable to blow ambient air across the first coil;
configure a second coil as an inactive coil by de-energizing each of one or more fans operable to blow ambient air across the second coil;
receive information from one or more remote sensors, the information comprising a pressure of refrigerant that is compressed by a compressor and ambient temperature information;
trigger a low ambient temperature mode in response to receiving ambient temperature information indicating an ambient temperature below the threshold temperature;
in response to triggering the low ambient temperature mode, monitor the refrigerant pressure based on the information received from the one or more remote sensors;
in response to determining that the refrigerant pressure is below the low threshold, pressure:
operate a first expansion valve coupled to the first coil to reduce refrigerant flow into a third coil through the first coil, wherein the third coil is coupled to the first coil and the third coil is further coupled to the compressor;
determine whether the first expansion valve is closed; and
in response in determining that the first expansion valve is closed, shut off the compressor and the one or more fans operable to blow ambient air across the first coil; and

in response to determining that the refrigerant pressure is above the high threshold pressure, operate a second expansion valve coupled to a second coil to reduce refrigerant flow into the third coil through the second coil, wherein the second coil is coupled to the third coil.

8. The apparatus of claim 7 , wherein in response to determining that the refrigerant pressure is above the high threshold pressure, the processor is further operable to increase a speed of at least one of the one or more fans operable to blow ambient air across the first coil.

9. The apparatus of claim 7 , wherein the first coil and the second coil are positioned outside a building and the third coil is positioned inside a building.

10. The apparatus of claim 9 , wherein at least some of the refrigerant evaporates as it passes through the third coil.

11. The apparatus of claim 9 , wherein at least some of the refrigerant condenses as it passes through the first and second coils.

12. The apparatus of claim 7 , wherein the processor is operable to receive ambient temperature information from a remote temperature sensor.

13. The system of claim 1 , wherein at least one of the one or more sensors is positioned internal to the compressor.

14. The system of claim 1 , wherein at least one of the one or more sensors is positioned external to the compressor.

15. The system of claim 1 , wherein at least one of the one or more sensors senses the refrigerant pressure at a suction of the compressor.

16. The system of claim 1 , wherein at least one of the one or more sensors senses the refrigerant pressure at a discharge of the compressor.

Assignees

• Lennox Ind Inc

Inventors

• Hung Der-Kai

Classifications

• Y02B30/70

  Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating · CPC title

• F25B2313/02743

  using three four-way valves · CPC title

• F25B13/00

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

• F04D19/002

  Axial flow fans · CPC title

• F25B2600/0253

  with variable speed · CPC title