Method for refrigerant pressure control in refrigeration systems

• US 20060288716A1
• Filed: 06/23/2005
• Published: 12/28/2006
• Est. Priority Date: 06/23/2005
• Status: Active Grant

• Current Assignee: Tyco Fire & Security GmbH (Johnson Controls International plc)
• Original Assignee: York International Corporation (Johnson Controls International plc)
• Inventors: Gavula, Patrick Gordon, Knight, John Terry, Landers, Anthony William, Pickle, Stephen Blake
• Granted Patent: US 7,559,207 B2
• Time in Patent Office: Days
• US Class Current: 62/196.400
• CPC Class Codes: F25B 2600/2517 Head-pressure valves
• CPC Class Codes: F25B 2600/2519 On-off valves
• CPC Class Codes: F25B 2700/19 Pressures
• CPC Class Codes: F25B 49/027 Condenser control arrangements

Abstract

A method and system for controlling refrigerant pressure in an HVAC system. The method includes providing a compressor, a condenser and an evaporator connected in a closed refrigerant loop. The condenser has a header arrangement capable of distributing refrigerant to a plurality of refrigerant circuits within the condenser. The header arrangement also is capable of selectively isolating at least one of the circuits from refrigerant flow. Refrigerant pressure is sensed at a predetermined location in the refrigeration system. At least one of the circuits is isolated when the refrigerant pressure is less than or equal to a predetermined pressure.

Claims

1. A method for controlling refrigerant pressure in an HVAC system comprising the steps of:

providing a compressor, a condenser and an evaporator connected in a closed refrigerant loop, the condenser having a header arrangement capable of distributing refrigerant to a plurality of refrigerant circuits within the condenser and capable of selectively isolating at least one of the circuits from refrigerant flow;

sensing refrigerant pressure at a predetermined location in the refrigeration system; and

isolating at least one of the refrigerant circuits, in response to the sensed refrigerant pressure being less than or equal to a predetermined pressure.

2. The method of claim 1, further comprising drawing refrigerant from the at least one refrigerant circuit isolated from refrigerant flow into the refrigerant loop to increase the refrigerant pressure in the refrigerant loop.

3. The method of claim 1, further comprising drawing refrigerant into the at least one refrigerant circuit isolated from refrigerant flow from the refrigerant loop to decrease the refrigerant pressure in the refrigerant loop.

4. The method of claim 1, wherein the step of isolating at least one refrigerant circuit includes the step of increasing refrigerant pressure by reducing an amount of heat transfer and a refrigerant temperature in the condenser.

5. The method of claim 1, wherein the at least one refrigerant circuit isolated from refrigerant flow is arranged and disposed in locations across a surface of the condenser that receive a reduced flow of heat transfer fluid during operation.

6. The method of claim 5, wherein the at least one refrigerant circuit isolated from refrigerant flow is arranged and disposed at locations at or near edges of the surface of the condenser.

7. The method of claim 1, wherein the predetermined pressure corresponds to a pressure resulting in icing of the evaporator.

8. A method for controlling refrigerant pressure in an HVAC system comprising:

providing a closed loop refrigerant system comprising a compressor, a condenser and an evaporator, the condenser having a header arrangement capable of distributing refrigerant to a plurality of refrigerant circuits within the condenser and capable of selectively isolating at least one of the circuits from refrigerant flow;

measuring refrigerant pressure at a predetermined location in the refrigeration system;

isolating at least one of the circuits from refrigerant flow when the measured pressure is equal to or less than a predetermined pressure; and

repeating the steps of measuring and isolating until the measured pressure is greater than the predetermined pressure.

9. The method of claim 8, wherein the predetermined location is between the outlet of the evaporator and the compressor.

10. The method of claim 9, wherein the predetermined pressure corresponds to a pressure resulting in icing of the evaporator.

11. The method of claim 8, further comprising drawing refrigerant into the refrigerant system from the at least one of the circuits isolated from refrigerant flow by fluidly connecting an isolated portion of the condenser including the at least one of the circuits isolated from refrigerant flow to an inlet of the compressor.

12. The method of claim 11, further comprising adding refrigerant from the isolated portion of the condenser to the refrigeration system to increase the refrigerant pressure.

13. The method of claim 8, further comprising drawing refrigerant from the refrigeration system into the at least one of the circuits isolated from refrigerant flow to decrease the refrigerant pressure.

14. The method of claim 8, wherein the at least one of the circuits isolated from refrigerant flow is arranged and disposed in locations across a surface of the condenser that receive a reduced flow of heat transfer fluid during operation.

15. The method of claim 14, wherein the at least one circuits isolated from refrigerant flow is arranged and disposed at locations at or near edges of the surface of the condenser.

16. The method of claim 8, wherein a number of circuits of the at least one of the circuits isolated within the condenser varies with a difference between the measure pressure and the predetermined pressure.

17. A heating, ventilation and air conditioning system comprising:

a compressor, an evaporator, and a condenser connected in a closed refrigerant loop;

a refrigerant pressure sensor to measure refrigerant pressure, the refrigerant pressure sensor being disposed at predetermined location within the refrigerant system;

the condenser including a plurality of refrigerant circuits, a first valve arrangement and a second valve arrangement;

the first valve arrangement arranged and disposed to isolate one or more of the refrigerant circuits from flow of refrigerant when the measured refrigerant pressure is below a predetermined pressure; and

the second valve arrangement arranged and disposed to draw refrigerant into or out of the one or more isolated refrigerant circuits of the condenser in response to the measured refrigerant pressure to maintained a predetermined system pressure.

18. The system of claim 17, wherein the first valve arrangement isolates the one or more refrigerant circuits to reduce the heat transfer area of the condenser.

19. The system of claim 17, wherein the second valve arrangement permits fluid communication of the one or more isolated refrigerant circuits with an inlet of the compressor.

20. The system of claim 17, wherein the first valve arrangement includes one or more valves configured and disposed in the refrigeration system to independently isolate one or more of the refrigerant circuits from flow of refrigerant.

21. The system of claim 17, wherein the one or more isolated refrigerant circuits are arranged and disposed in locations across a surface of the condenser that receive a reduced flow of heat transfer fluid during operation.

22. The system of claim 21, wherein the one or more isolated refrigerant circuits are arranged and disposed at locations at or near edges of the surface of the condenser.

23. The system of claim 17, wherein the first valve arrangement and second valve arrangement comprise a single inlet header.

24. The system of claim 17, wherein the first valve arrangement and second valve arrangement comprise a plurality of inlet headers.

25. The system of claim 17, wherein the first valve arrangement and second valve arrangement comprise a single outlet header.

26. The system of claim 17, wherein the first valve arrangement and second valve arrangement comprise a plurality of outlet headers.