Refrigeration system

Patent metadata

Field	Value
Publication number	US-11598564-B2
Application number	US-202017127495-A
Country	US
Kind code	B2
Filing date	Dec 18, 2020
Priority date	Dec 19, 2019
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

A refrigeration system includes a main refrigeration circuit for holding refrigerant fluid, the main refrigeration circuit including: a compression device 12 , a heat rejecting heat exchanger 14 , an expansion device 18 and a heat absorbing heat exchanger 16 . In addition, the refrigeration system includes a buffer tank 20 attached to the main refrigeration circuit, with valves 22, 24 for controlling flow of refrigerant fluid between the main refrigeration circuit and the buffer tank 20 . The refrigeration system is arranged such that the valves 22, 24 are controlled to transfer refrigerant fluid between the main refrigeration circuit and the buffer tank 20 based on a measure of sub-cooling in the main refrigeration circuit.

First claim

What is claimed is:

1. A refrigeration system comprising:
a main refrigeration circuit for holding refrigerant fluid, the main refrigeration circuit including: a compression device, a heat rejecting heat exchanger, an expansion device and a heat absorbing heat exchanger;
a sub-cooling sensor for obtaining the measure of sub-cooling;
wherein the refrigeration system includes a buffer tank attached to the main refrigeration circuit, with valves for controlling flow of refrigerant fluid between the main refrigeration circuit and the buffer tank;
a controller configured to control the valves; and
wherein the refrigeration system is arranged such that the valves are controlled by the controller to transfer refrigerant fluid between the main refrigeration circuit and the buffer tank based on a measure of sub-cooling in the main refrigeration circuit;
wherein the valves comprise a first valve for controlling flow to or from a higher pressure point on the refrigerant circuit, and a second valve for controlling flow to or from a lower pressure point on the refrigerant circuit;
wherein the second valve is a valve with a controllable degree of opening and the controller is configured to vary the degree of opening whilst the refrigerant fluid is being transferred from the buffer tank to the main refrigeration circuit;
wherein the controller is configured to control the degree of opening of the second valve is used in order to control the amount of liquid refrigerant fluid at an inlet of the compression device such as to avoid any liquid refrigerant that may damage the compression device.

2. A refrigeration system as claimed in claim 1 , wherein the buffer tank is connected to the main refrigeration circuit in parallel with the expansion device, with fluid connections to a higher pressure point prior to expansion, and a lower pressure point after expansion.

3. A refrigeration system as claimed in claim 1 , wherein the sub-cooling sensor is located on the main refrigeration circuit after the heat rejecting heat exchanger and before the expansion device.

4. A refrigeration system as claimed in claim 1 , comprising a controller for controlling the valves, wherein the controller is configured such that when the measure of sub-cooling indicates there is excessive sub-cooling then refrigerant fluid is directed into the buffer tank from the main refrigeration circuit, and when there is insufficient sub-cooling then refrigerant fluid is emptied from the buffer tank into the main refrigeration circuit to thereby refill the main refrigeration circuit.

5. A refrigeration system as claimed in claim 1 , wherein the refrigeration system is arranged such that when it is desired to decrease charge levels in the main refrigeration circuit then the first valve is opened to fill the buffer tank from the higher pressure point, and when it is desired to increase charge levels in the main refrigeration circuit then the second valve is opened to empty the buffer tank to the lower pressure point.

6. A refrigeration system as claimed in claim 1 , wherein the expansion device is arranged to provide a controllable degree of expansion, and the refrigeration system is arranged to control the degree of opening of the expansion valve in reaction to changes in the behaviour of the refrigerant circuit.

7. A method for operating a refrigeration system as claimed in claim 1 , the method comprising controlling the valves to transfer refrigerant fluid between the main refrigeration circuit and the buffer tank based on a measure of sub-cooling in the main refrigeration circuit.

8. A method as claimed in claim 7 , wherein controlling of the valves is done to vary the refrigerant charge level of the main refrigeration circuit in order to allow for one or more of: increased efficiency during changes in operating conditions, an enlarged operating envelope of the refrigerant system, and/or adjustments as refrigerant charge is depleted over time.

9. A method as claimed in claim 7 , including controlling the valves for directing refrigerant fluid into the buffer tank from the main refrigeration circuit when there is excessive sub-cooling, and for directing refrigerant fluid from the buffer tank into the main refrigeration circuit when there is insufficient sub-cooling.

10. A method as claimed in claim 7 , including:
when there is over-sub-cooling, opening a first valve with a second valve being closed;
when there is insufficient sub-cooling, opening the second valve with the first valve being closed; and
when it is required to keep the refrigerant charge level of the main circuit unchanged, keeping both the first valve and second valve closed.

11. A method as claimed in claim 7 , including varying the degree of opening of the respective valve whilst the refrigerant fluid is being transferred from the buffer tank to the main refrigeration circuit in order to control the amount of liquid refrigerant fluid at an inlet of the compression device.

12. A refrigeration system as claimed in claim 1 , wherein the first valve is connected to the main refrigeration circuit between the heat rejecting heat exchanger and the expansion device and the second valve is connected to the main refrigeration circuit between the expansion device and the heat absorbing heat exchanger.

Assignees

• Carrier Corp

Inventors

• Fonte Nicolas

Classifications

• F25B49/02 Primary

  for compression type machines, plants or systems · CPC title

• F25B2700/2103

  near a heat exchanger · CPC title

• F25B2600/2513

  Expansion valves · CPC title

• F25B1/00 Primary

  Compression machines, plants or systems with non-reversible cycle (F25B3/00, F25B5/00, F25B6/00, F25B7/00, F25B9/00 take precedence) · CPC title

• F25B2400/0415

  for receivers · CPC title