Method for operating a vapour compression system with a receiver

Patent metadata

Field	Value
Publication number	US-10941964-B2
Application number	US-201515527496-A
Country	US
Kind code	B2
Filing date	Oct 7, 2015
Priority date	Nov 19, 2014
Publication date	Mar 9, 2021
Grant date	Mar 9, 2021

Abstract

A method for controlling a vapour compression system, the vapour compression system including a compressor unit with one or more compressors. At least one of the compressors is connectable to a gaseous outlet of a receiver, and at least one of the compressors is connectable to an outlet of an evaporator. A parameter of the vapour compression system is measured, an enthalpy of refrigerant leaving the heat rejecting heat exchanger being derivable from the measured parameter. A setpoint value for a pressure inside the receiver is calculated, based on the measured parameter, and the compressor unit is operated in accordance with the calculated setpoint value, and in order to obtain a pressure inside the receiver which is equal to the calculated setpoint value. The vapour compression system is operated in an energy efficient manner over a wide range of ambient temperatures.

First claim

What is claimed is:

1. A method for controlling a vapour compression system, the vapour compression system comprising:
a compressor unit comprising one or more main compressors and one or more receiver compressors;
a heat rejecting heat exchanger;
a high pressure valve;
a receiver;
an expansion device;
an evaporator arranged in a refrigerant path; and
a bypass valve arranged in a refrigerant path interconnecting the receiver and the compressor unit;
wherein at least one of the main compressors of the compressor unit is connectable to a gaseous outlet of the receiver, and at least one of the main compressors of the compressor unit is connectable to an outlet of the evaporator; and
wherein at least one receiver compressor of the one or more receiver compressors is connected through a connecting line to the refrigerant path interconnecting the receiver and the compressor unit at a point between the receiver and the bypass valve;
the method comprising the steps of:
measuring a parameter of the vapour compression system, where an enthalpy of refrigerant leaving the heat rejecting heat exchanger can be derived from the measured parameter;
deriving the enthalpy of refrigerant leaving the heat rejecting heat exchanger from the measured parameter;
calculating a setpoint value for a pressure inside the receiver, based on the derived enthalpy; and
operating the compressor unit in accordance with the calculated setpoint value, and in order to obtain a pressure inside the receiver which is equal to the calculated setpoint value.

2. The method according to claim 1 , wherein the step of measuring a parameter comprises measuring an ambient temperature prevailing in a region of the heat rejecting heat exchanger.

3. The method according to claim 1 , wherein the step of measuring a parameter comprises measuring a temperature of refrigerant leaving the heat rejecting heat exchanger.

4. The method according to claim 1 , wherein the step of measuring a parameter comprises measuring a pressure of refrigerant leaving the heat rejecting heat exchanger.

5. The method according to claim 1 , wherein the vapour compression system is arranged to have a transcritical refrigerant flowing in the refrigerant path.

6. The method according to claim 1 , wherein the heat rejecting heat exchanger is a gas cooler.

7. The method according to claim 1 , wherein the method further comprises the step of opening the bypass valve in the case that the pressure inside the receiver decreases below a predefined threshold value.

8. The method according to claim 1 , wherein the step of calculating a setpoint comprises solving the equation:
P setpoint =a·x+b,
wherein a and b are predefined constants depending on thermophysical properties of a refrigerant flowing in the refrigerant path, P setpoint is the setpoint value for the pressure inside the receiver, and x is the measured parameter.

9. The method according to claim 1 , wherein at least one main compressor of the one or more main compressors is connected between an outlet of the evaporator and an inlet of the heat rejecting heat exchanger, and at least one receiver compressor of the one or more receiver compressors is connected between a gaseous outlet of the receiver and an inlet of the heat rejecting heat exchanger, and wherein the step of operating the compressor unit in accordance with the calculated setpoint value comprises operating the one or more receiver compressors.

10. The method according to claim 1 , wherein at least one of the main compressors of the compressor unit is selectively connectable to the gaseous outlet of the receiver or to the outlet of the evaporator, and wherein the step of operating the compressor unit in accordance with the calculated setpoint value comprises switching at least one main compressor between being connected to the gaseous outlet of the receiver and being connected to the outlet of the evaporator.

11. The method according to claim 1 , wherein the vapour compression system further comprises a heat exchanger arranged in a refrigerant path interconnecting the gaseous outlet of the receiver and the compressor unit.

12. The method according to claim 2 , wherein the step of measuring a parameter comprises measuring a temperature of refrigerant leaving the heat rejecting heat exchanger.

13. The method according to claim 2 , wherein the step of measuring a parameter comprises measuring a pressure of refrigerant leaving the heat rejecting heat exchanger.

14. The method according to claim 3 , wherein the step of measuring a parameter comprises measuring a pressure of refrigerant leaving the heat rejecting heat exchanger.

15. The method according to claim 2 , wherein the vapour compression system is arranged to have a transcritical refrigerant flowing in the refrigerant path.

16. The method according to claim 3 , wherein the vapour compression system is arranged to have a transcritical refrigerant flowing in the refrigerant path.

17. The method according to claim 4 , wherein the vapour compression system is arranged to have a transcritical refrigerant flowing in the refrigerant path.

18. The method according to claim 2 , wherein the heat rejecting heat exchanger is a gas cooler.

19. The method according to claim 3 , wherein the heat rejecting heat exchanger is a gas cooler.

20. The method according to claim 4 , wherein the heat rejecting heat exchanger is a gas cooler.

21. A method for controlling a vapour compression system, the vapour compression system comprising:
a compressor unit comprising one or more compressors;
a heat rejecting heat exchanger;
a high pressure valve;
a receiver;
an expansion device; and
an evaporator arranged in a refrigerant path;
wherein at least one of the compressors of the compressor unit is connectable to a gaseous outlet of the receiver;
wherein at least one of the compressors of the compressor unit is connectable to an outlet of the evaporator; and
wherein at least one compressor of the one or more compressors is provided with a compressor valve switchable between a first position where the at least one compressor is configured to receive refrigerant supplied from the outlet of the evaporator, and a second position where the at least one compressor is configured to receive refrigerant supplied from the gaseous outlet of the receiver;
the method comprising the steps of:
measuring a parameter of the vapour compression system, where an enthalpy of refrigerant leaving the heat rejecting heat exchanger can be derived from the measured parameter,
deriving the enthalpy of refrigerant leaving the heat rejecting heat exchanger from the measured parameter;
calculating a setpoint value for a pressure inside the receiver, based on the derived enthalpy, and
operating the compressor unit in accordance with the calculated setpoint value, and in order to obtain a pressure inside the receiver which is equal to the calculated setpoint value.

22. The method according to claim 21 , wherein the vapour compression system further comprises a bypass valve arranged in a refrigerant path interconnecting the receiver and the compressor unit, and wherein at least one compressor of the one or more compressors is connected through a connecting line to the refrigerant path interconnecting the receiver and the compressor unit at a point between the receiver and the bypass valve.

23. The method according to claim 1 , wherein the step of operating the compressor unit in acc

Assignees

• Danfoss As

Inventors

• Fredslund Kristian
• Schmidt Frede
• Madsen Kenneth Bank
• Prins Jan

Classifications

• F25B41/39

  Dispositions with two or more expansion means arranged in series, i.e. multi-stage expansion, on a refrigerant line leading to the same evaporator · CPC title

• F25B2400/23

  Separators · CPC title

• F25B2700/195

  of the condenser · CPC title

• Y02B30/70

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

• F25B2600/2509

  Economiser valves · CPC title