Low suction pressure protection for refrigerant vapor compression system

Patent metadata

Field	Value
Publication number	US-9335079-B2
Application number	US-201013500686-A
Country	US
Kind code	B2
Filing date	Nov 22, 2010
Priority date	Nov 25, 2009
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

The present disclosure provides a refrigerant vapor compression system includes a compressor ( 12 ) having a suction port and a discharge port, a refrigerant heat rejection heat exchanger ( 24 ) operatively coupled downstream to the discharge port of the compressor, a refrigerant heat absorption heat exchanger ( 42 ) operatively coupled downstream to the refrigerant heat rejection heat exchanger, a compressor suction inlet line connecting the refrigerant heat absorption heat exchanger to the suction port of the compressor, and an adiabatic expansion device ( 54 ) operatively coupled to the suction inlet line. A sensor operatively coupled to the suction inlet line measures a superheat value of the refrigerant. The refrigerant vapor compression system further includes a controller ( 60 ) in communication with the sensor. The controller is configured to operate the refrigerant vapor compression system in a first mode when a pressure of the refrigerant downstream of the adiabatic expansion device is greater than a threshold value, and operate the refrigerant vapor compression system in a second mode when the pressure of the refrigerant downstream of the adiabatic expansion device is less than the threshold value. The compressor continues to operate in both the first mode and the second mode.

First claim

We claim:

1. A refrigerant vapor compression system comprising:
a compressor for compressing a refrigerant, the compressor having a suction port and a discharge port; a refrigerant heat rejection heat exchanger operatively coupled downstream to the discharge port of the compressor; a refrigerant heat absorption heat exchanger operatively coupled downstream to the refrigerant heat rejection heat exchanger; a compressor suction inlet line connecting the refrigerant heat absorption heat exchanger to the suction port of the compressor; an adiabatic expansion device operatively coupled to the suction inlet line;
a sensor operatively coupled to the suction inlet line for measuring a superheat value of the refrigerant;
a bypass line connecting the discharge port of the compressor to the suction port of the compressor, the bypass line having an unload valve to regulate the refrigerant flow therethrough;
wherein the adiabatic expansion device is positioned upstream with respect to refrigerant flow of a point where the bypass line connects to the suction inlet line;
a controller in communication with the sensor, the controller configured to operate the refrigerant vapor compression system in a first cooling mode when a pressure of the refrigerant downstream of the adiabatic expansion device is greater than a threshold value, and operate the refrigerant vapor compression system in a second cooling mode when the pressure of the refrigerant downstream of the adiabatic expansion device is less than the threshold value, the threshold value indicative of a pressure at which expansion across the adiabatic expansion device would result in formation of solid-phase refrigerant;
wherein the second cooling mode of operation includes opening the unload valve to admit higher-temperature refrigerant to the suction port of the compressor; and
wherein the compressor continues to operate in both cooling modes, wherein the refrigerant vapor compression system operates in a transcritical mode in both the first cooling mode and the second cooling mode.

2. The refrigerant vapor compression system of claim 1 , wherein the adiabatic expansion device is a suction modulation valve.

3. The refrigerant vapor compression system of claim 1 , wherein the second cooling mode comprises increasing the superheat value of the refrigerant in the suction inlet line.

4. The refrigerant vapor compression system of claim 1 , wherein the second cooling mode comprises increasing a pressure upstream of the adiabatic expansion device until a pressure downstream of the adiabatic expansion device is above the triple point pressure of the refrigerant.

5. The refrigerant vapor compression system of claim 1 , wherein the threshold value is a fixed value greater than a triple point pressure of the refrigerant.

6. The refrigerant vapor compression system of claim 5 , wherein the threshold value is equal to the triple point pressure of the refrigerant.

7. The refrigerant vapor compression system of claim 1 , further including an expansion valve upstream of the refrigerant heat absorption heat exchanger, wherein increasing the superheat value comprises adjusting the expansion valve.

8. The refrigerant vapor compression system of claim 7 , wherein adjusting the expansion valve comprises closing down the expansion valve.

9. The refrigerant vapor compression system of claim 1 , further comprising a heater disposed in thermal contact with the suction inlet line, wherein increasing the superheat value of the refrigerant comprises powering the heater.

10. The refrigerant vapor compression system of claim 1 , wherein operating the refrigerant vapor compression system in the second cooling mode further comprises operating with a pressure at the suction port of the compressor being less than the triple point pressure of the refrigerant.

11. The refrigerant vapor compression system of claim 1 , wherein the refrigerant is carbon dioxide.

Assignees

• Huff Hans-Joachim
• Duraisamy Suresh
• Carrier Corp

Inventors

• Huff Hans-Joachim
• Duraisamy Suresh

Classifications

• F25B9/008 Primary

  the refrigerant being carbon dioxide · CPC title

• F25B2700/21172

  at the inlet · CPC title

• F25B2600/0261

  external to the compressor · CPC title

• F25B2341/0662

  Mechanical Engineering · mapped topic

• F25B2600/2509

  Economiser valves · CPC title