Systems and methods for pressure control in a co2 refrigeration system

Patent metadata

Field	Value
Publication number	US-2016102901-A1
Application number	US-201414787666-A
Country	US
Kind code	A1
Filing date	Apr 30, 2014
Priority date	May 3, 2013
Publication date	Apr 14, 2016
Grant date	—

Abstract

Systems and methods for controlling pressure in a CO 2 refrigeration system are provided. The pressure control system includes a pressure sensor, a gas bypass valve, a parallel compressor, and a controller. The pressure sensor is configured to measure a pressure within a receiving tank of the CO 2 refrigeration system. The gas bypass valve is fluidly connected with an outlet of the receiving tank and arranged in series with a compressor of the CO 2 refrigeration system. The parallel compressor is fluidly connected with the outlet of the receiving tank and arranged in parallel with both the gas bypass valve and the compressor of the CO 2 refrigeration system. The controller is configured to receive a pressure measurement from the pressure sensor and operate both the gas bypass valve and the parallel compressor, in response to the pressure measurement, to control the pressure within the receiving tank.

First claim

What is claimed is:

1 . A system for controlling pressure in a CO 2 refrigeration system, the system for controlling pressure comprising:
a pressure sensor configured to measure a pressure within a receiving tank of the CO 2 refrigeration system; a gas bypass valve fluidly connected with an outlet of the receiving tank and arranged in series with a compressor of the CO 2 refrigeration system; a parallel compressor fluidly connected with the outlet of the receiving tank and arranged in parallel with both the gas bypass valve and the compressor of the CO 2 refrigeration system; and a controller configured to:
receive a pressure measurement from the pressure sensor, and
operate both the gas bypass valve and the parallel compressor, in response to the pressure measurement, to control the pressure within the receiving tank.

2 . The system of claim 1 , wherein the controller comprises an extensive control module configured to:
receive an indication of a CO 2 refrigerant flow rate through the gas bypass valve; receive the pressure measurement from the pressure sensor; and operate both the gas bypass valve and the parallel compressor in response to both the indication of the CO 2 refrigerant flow rate and the pressure measurement.

3 . The system of claim 2 , wherein the extensive control module is further configured to:
compare the indication of the CO 2 refrigerant flow rate with a threshold value, the threshold value indicating a threshold flow rate through the gas bypass valve; and activate the parallel compressor in response to the indication of the CO 2 refrigerant flow rate exceeding the threshold value.

4 . The system of claim 2 , wherein the indication of the CO 2 refrigerant flow rate is one of: a position of the gas bypass valve, a volume flow rate of the CO 2 refrigerant through the gas bypass valve, and a mass flow rate of the CO 2 refrigerant through the gas bypass valve.

5 . The system of claim 1 , wherein the controller comprises an intensive control module configured to:
receive an indication of a CO 2 refrigerant temperature; receive the pressure measurement from the pressure sensor; and operate both the gas bypass valve and the parallel compressor in response to both the indication of the CO 2 refrigerant temperature and the pressure measurement.

6 . The system of claim 5 , wherein the indication of the CO 2 refrigerant temperature indicates a temperature of CO 2 refrigerant at an outlet of a gas cooler/condenser of the CO 2 refrigeration system.

7 . The system of claim 5 , wherein the intensive control module is further configured to:
compare the indication of the CO 2 refrigerant temperature with a threshold value, the threshold value indicating a threshold temperature for the CO 2 refrigerant; activate the parallel compressor in response to the indication of the CO 2 refrigerant temperature exceeding the threshold value.

8 . The system of claim 1 , wherein the controller is further configured to:
determine a pressure within the receiving tank based on the measurement from the pressure sensor; compare the pressure within the receiving tank to a first threshold pressure and a second threshold pressure higher than the first threshold pressure; and control the pressure within the receiving tank using:
only the gas bypass valve in response to a determination that the pressure within the receiving tank is between the first threshold pressure and the second threshold pressure, and
both the gas bypass valve and the parallel compressor in response to a determination that the pressure within the receiving tank exceeds the second threshold pressure.

9 . The system of claim 8 , wherein the controller is further configured to:
adjust the first threshold pressure and the second threshold pressure in response to a determination that the pressure within the receiving tank exceeds the second threshold pressure, wherein adjusting the first threshold pressure involves increasing the first threshold pressure to a first adjusted threshold pressure value and wherein adjusting the second threshold pressure involves decreasing the second threshold pressure to a second adjusted threshold pressure value lower than the first adjusted threshold pressure value.

10 . The system of claim 9 , wherein after adjusting the first threshold pressure and the second threshold pressure, the controller is configured to:
control the pressure within the receiving tank using only the parallel compressor in response to a determination that the pressure within the receiving tank is between the first adjusted threshold pressure and the second adjusted threshold pressure, and deactivate the parallel compressor in response to a determination that the pressure within the receiving tank is less than the second adjusted threshold pressure.

11 . The system of claim 9 , wherein the controller is further configured to:
reset the first threshold pressure and the second threshold pressure to non-adjusted threshold pressure values in response to a determination that the pressure within the receiving tank is less than the second adjusted threshold pressure.

12 . A method for controlling pressure in a CO 2 refrigeration system, the method comprising:
receiving, at a controller, a measurement indicating a pressure within a receiving tank of the CO 2 refrigeration system; operating a gas bypass valve fluidly connected with an outlet of the receiving tank, the gas bypass valve arranged in series with a compressor of the CO 2 refrigeration system; and operating a parallel compressor fluidly connected with the outlet of the receiving tank, the parallel compressor arranged in parallel with both the gas bypass valve and the compressor of the CO 2 refrigeration system, wherein the gas bypass valve and parallel compressor are operated in response to the measurement from the pressure sensor to control the pressure within the receiving tank.

13 . The method of claim 12 , further comprising:
receiving an indication of a CO 2 refrigerant flow rate through the gas bypass valve; and operating both the gas bypass valve and the parallel compressor in response to both the indication of the CO 2 refrigerant flow rate and the measurement from the pressure sensor.

14 . The method of claim 13 , further comprising:
comparing the indication of the CO 2 refrigerant flow rate with a threshold value, the threshold value indicating a threshold flow rate through the gas bypass valve; and activating the parallel compressor in response to the indication of the CO 2 refrigerant flow rate exceeding the threshold value.

15 . The method of claim 13 , wherein the indication of the CO 2 refrigerant flow rate is one of: a position of the gas bypass valve, a volume flow rate of the CO 2 refrigerant through the gas bypass valve, and a mass flow rate of the CO 2 refrigerant through the gas bypass valve.

16 . The method of claim 12 , further comprising:
receiving an indication of a CO 2 refrigerant temperature an outlet of a gas cooler/condenser of the CO 2 refrigeration system; and operating both the gas bypass valve and the parallel compressor in response to both the indication of the CO 2 refrigerant temperature and the measurement from the pressure sensor

17 . The method of claim 16 , further comprising:
comparing the indication of the CO 2 refrigerant temperature with a threshold value, the threshold value indicating a threshold temperature for the CO 2 refrigerant; and activating the parallel compressor in response to the indication

Assignees

• Hill Phoenx Inc
• Hill Phoenix Inc

Inventors

• Christensen Kim G
• Newel Jeffrey
• Bittner John D

Classifications

• F25B1/10

  with multi-stage compression (with cascade operation F25B7/00) · CPC title

• F25B2700/13

  Mass flow of refrigerants · CPC title

• F25B40/00

  Subcoolers, desuperheaters or superheaters · CPC title

• F25B2500/07

  Exceeding a certain pressure value in a refrigeration component or cycle · CPC title

• F25B9/008

  the refrigerant being carbon dioxide · CPC title