Method for controlling a valve arrangement in a vapour compression system

Patent metadata

Field	Value
Publication number	US-10378796-B2
Application number	US-201515531989-A
Country	US
Kind code	B2
Filing date	Oct 8, 2015
Priority date	Dec 9, 2014
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A method for controlling a valve arrangement ( 12 ), e.g. in the form of a three way valve, in a vapor compression system ( 1 ) is disclosed, the vapor compression system ( 1 ) comprising an ejector ( 6 ). The valve arrangement ( 12 ) is arranged to supply refrigerant to a compressor unit ( 2 ) from the gaseous outlet ( 11 ) of a receiver ( 7 ) and/or from the outlet of an evaporator ( 9 ). The vapor compression system ( 1 ) may be operated in a first mode of operation (summer mode) or in a second mode of operation (winter mode). When operated in the second mode of operation, it is determined whether or not conditions for operating the vapor compression system ( 1 ) in the first mode of operation are prevailing. If this is the case, the valve arrangement ( 12 ) is actively switched to the first mode of operation by closing a first inlet ( 13 ) towards the evaporator ( 7 ) and fully opening a second inlet ( 14 ) towards the receiver ( 7 ).

First claim

What is claimed is:

1. A method for controlling a valve arrangement in a vapour compression system, the vapour compression system comprising a compressor unit comprising one or more compressors, a heat rejecting heat exchanger, an ejector, a receiver, an expansion device and an evaporator arranged in a refrigerant path, wherein an outlet of the heat rejecting heat exchanger is connected to a primary inlet of the ejector, an outlet of the ejector is connected to the receiver, an outlet of the evaporator is connected to a secondary inlet of the ejector and to a first inlet of the valve arrangement, a gaseous outlet of the receiver is connected to a second inlet of the valve arrangement, and an outlet of the valve arrangement is connected to an inlet of the compressor unit, the valve arrangement thereby being arranged to supply refrigerant to the compressor unit from the gaseous outlet of the receiver and/or from the outlet of the evaporator, the method comprising the steps of:
defining a first mode of operation of the vapour compression system, in which the valve arrangement is operated to keep the first inlet of the valve arrangement closed and to keep the second inlet of the valve arrangement open,
defining a second mode of operation of the vapour compression system, in which the valve arrangement is operated to keep the first inlet of the valve arrangement open and to operate the second inlet of the valve arrangement to bypass vapour in order to maintain a pressure level in the receiver,
when operating the vapour compression system in the second mode of operation:
determining whether conditions for operating the vapour compression system in the first mode of operation are prevailing, and
actively closing the first inlet of the valve arrangement and fully opening the second inlet of the valve arrangement based on the determination that the conditions for operating the vapour compression system in the first mode of operation are prevailing.

2. The method according to claim 1 , wherein the step of determining whether the conditions for operating the vapour compression system in the first mode of operation are prevailing comprises the steps of:
determining a distribution of refrigerant supplied to the valve arrangement, including determining how large a portion of the refrigerant being supplied from the outlet of the valve arrangement to the compressor unit is received in the valve arrangement via the first inlet, and how large a portion is received via the second inlet, and
determining that conditions for operating the vapour compression system in the first mode of operation are prevailing if the portion of refrigerant received via the second inlet of the valve arrangement exceeds a predefined percentage of the refrigerant supplied from the outlet of the valve arrangement to the inlet of the compressor unit, said predefined percentage being at least 70%.

3. The method according to claim 2 , wherein the step of determining a distribution of refrigerant supplied to the valve arrangement comprises measuring a temperature of refrigerant entering the valve arrangement via the first inlet, a temperature of refrigerant entering the valve arrangement via the second inlet, and a temperature of refrigerant leaving the valve arrangement via the outlet, and comparing the measured temperatures.

4. The method according to claim 2 , wherein the step of determining a distribution of refrigerant supplied to the valve arrangement comprises determining an opening degree of the second inlet of the valve arrangement.

5. The method according to claim 2 , wherein the step of determining a distribution of refrigerant supplied to the valve arrangement comprises the step of determining a flow direction of refrigerant at the first inlet of the valve arrangement.

6. The method according to claim 5 , wherein the step of determining a flow direction of refrigerant at the first inlet of the valve arrangement comprises the steps of:
modulating an opening degree of the first inlet of the valve arrangement, and
measuring changes in a pressure of refrigerant at the first inlet of the valve arrangement in response to the modulation of the opening degree of the first inlet of the valve arrangement.

7. The method according to claim 1 , wherein the step of determining whether the conditions for operating the vapour compression system in the first mode of operation are prevailing comprises 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, and
determining that conditions for operating the vapour compression system in the first mode of operation are prevailing if the measured parameter exceeds a predefined threshold value.

8. The method according to claim 1 , wherein the valve arrangement is or comprises a three way valve.

9. The method according to claim 1 , wherein the vapour compression system further comprises a high pressure valve interconnecting an outlet of the heat rejecting heat exchanger and an inlet of the receiver, the high pressure valve being arranged in parallel to the ejector, and wherein refrigerant leaving the heat rejecting heat exchanger is divided into a flow passing through the high pressure valve and a flow passing through the ejector, via the primary inlet of the ejector.

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

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

12. The method according to claim 3 , wherein the step of determining a distribution of refrigerant supplied to the valve arrangement comprises determining an opening degree of the second inlet of the valve arrangement.

13. The method according to claim 3 , wherein the step of determining a distribution of refrigerant supplied to the valve arrangement comprises the step of determining a flow direction of refrigerant at the first inlet of the valve arrangement.

14. The method according to claim 4 , wherein the step of determining a distribution of refrigerant supplied to the valve arrangement comprises the step of determining a flow direction of refrigerant at the first inlet of the valve arrangement.

15. The method according to claim 2 , wherein the valve arrangement is or comprises a three way valve.

16. The method according to claim 3 , wherein the valve arrangement is or comprises a three way valve.

17. The method according to claim 4 , wherein the valve arrangement is or comprises a three way valve.

18. The method according to claim 5 , wherein the valve arrangement is or comprises a three way valve.

19. The method according to claim 6 , wherein the valve arrangement is or comprises a three way valve.

20. The method according to claim 7 , wherein the valve arrangement is or comprises a three way valve.

Assignees

• Danfoss As

Inventors

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

Classifications

• F25B2700/195

  of the condenser · CPC title

• F25B2400/23

  Separators · CPC title

• F25B2500/31

  Low ambient temperatures · CPC title

• F25B2700/21175

  of the refrigerant at the outlet of the evaporator · CPC title

• F25B2309/061

  with cycle highest pressure above the supercritical pressure · CPC title