Parallel capillary expansion tube systems and methods

Patent metadata

Field	Value
Publication number	US-10502468-B2
Application number	US-201715718291-A
Country	US
Kind code	B2
Filing date	Sep 28, 2017
Priority date	Oct 5, 2016
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

A cooling system includes a subcooling heat exchange assembly, which controls magnitude of subcooling of refrigerant circulated through the cooling system. The subcooling heat exchange assembly includes a first fluid line fluidly coupled to an output of a condenser to enable a first portion of the refrigerant output from the condenser to flow through the first fluid line; a second fluid line fluidly coupled to the output of the condenser to enable a second portion of the refrigerant output from the condenser to flow through the second fluid line; and an expansion valve disposed along the second fluid line, in which the expansion valve exerts a first pressure drop on the second portion of the refrigerant that facilitates extracting heat from the first portion of the refrigerant flowing through the first fluid line using the second portion of the refrigerant flowing through the second fluid line when valve position of the expansion valve is greater than a threshold position. Additionally the cooling system includes a plurality of capillary expansion tubes fluidly coupled in parallel to an output of the first fluid line and that to exert a second pressure drop on the refrigerant circulated through the cooling system.

First claim

The invention claimed is:

1. A cooling system, comprising:
a subcooling heat exchange assembly configured to control a magnitude of subcooling of refrigerant circulated through the cooling system, wherein the subcooling heat exchange assembly comprises:
a first fluid line configured to be fluidly coupled to an output of a condenser to enable a first portion of the refrigerant output from the condenser to flow through the first fluid line;
a second fluid line configured to be fluidly coupled to the output of the condenser to enable a second portion of the refrigerant output from the condenser to flow through the second fluid line to a suction line at a first location of the suction line; and
an expansion valve disposed along the second fluid line, wherein the expansion valve is configured to exert a first pressure drop on the second portion of the refrigerant that facilitates extracting heat from the first portion of the refrigerant flowing through the first fluid line using the second portion of the refrigerant flowing through the second fluid line when valve position of the expansion valve is greater than a threshold position; and

a plurality of capillary expansion tubes fluidly coupled in parallel to an output of the first fluid line and configured to exert a second pressure drop on the refrigerant circulated through the cooling system;
an evaporator heat exchanger fluidly coupled to the plurality of expansion tubes; and
a sensing bulb disposed at a second location of the suction line and communicatively coupled to the expansion valve, wherein the second location is downstream of the first location, and wherein the sensing bulb is configured to:
measure a temperature and a pressure of the refrigerant output from the evaporator heat exchanger; and
adjust the valve position of the expansion valve to a more open position when the temperature and pressure of the refrigerant output from the evaporator heat exchanger increase.

2. The cooling system of claim 1 , wherein the expansion valve divides the second fluid line into a first portion and a second portion, wherein the second portion is coiled around the first fluid line before an input to each of the plurality of capillary expansion tubes.

3. The cooling system of claim 1 , wherein:
the evaporator heat exchanger comprises a plurality of evaporator paths;
each of the plurality of evaporator paths is fluidly coupled to a corresponding one of the plurality of capillary expansion tubes;
each of the plurality of evaporator paths is configured to facilitate heat exchange between the refrigerant circulated through the evaporator heat exchanger and a surrounding fluid; and
the subcooling heat exchange assembly is configured to control the magnitude of subcooling of the refrigerant entering the plurality of capillary expansion tubes to facilitate substantially uniformly distributing a mass flow of the refrigerant between each of the plurality of evaporator paths.

4. The cooling system of claim 1 , wherein a pressure increase within the sensing bulb causes the expansion valve to adjust the valve position to an intermediate position greater than the threshold position.

5. The cooling system of claim 1 , comprising a compressor configured to drive circulation of the refrigerant through the cooling system, wherein the subcooling heat exchange assembly is configured to adjust the magnitude of subcooling of the refrigerant before the refrigerant enters the plurality of capillary expansion tubes based at least in part on an operating capacity of the compressor.

6. The cooling system of claim 5 , wherein the compressor comprises a variable speed compressor or a plurality of tandem compressors.

7. The cooling system of claim 5 , wherein the threshold position of the expansion valve corresponds to the operating capacity at which the compressor is expected to be operating.

8. The cooling system of claim 7 , wherein each of the plurality of capillary expansion tubes is sized to facilitate substantially uniform distribution of a mass flow of the refrigerant between each of the plurality of capillary expansion tubes when:
the expansion valve is in the threshold position; and
the compressor is operating at the operating capacity at which the compressor is expected to be operating.

9. The cooling system of claim 1 , wherein the expansion valve is configured to control a flow rate of the second portion of refrigerant through the second fluid line.

10. The cooling system of claim 1 , wherein controlling the magnitude of subcooling of the refrigerant comprises increasing the subcooling of the first portion of refrigerant in the first fluid line, wherein increasing the subcooling of the first portion of the refrigerant increases a choked mass flow rate of the refrigerant across the plurality of capillary expansion tubes.

11. The cooling system of claim 1 , wherein the expansion valve divides the second fluid line into a first portion and a second portion, wherein the second portion is configured to enable the second portion of the refrigerant output from the condenser to flow through a heat exchanger and transfer heat with the first portion of the refrigerant output from the condenser flowing through the first fluid line before an input to each of the plurality of capillary expansion tubes.

12. The cooling system of claim 1 , wherein the expansion valve comprises a thermostatic expansion valve.

13. A method for operating a cooling system, comprising:
sensing a temperature and a pressure of refrigerant output from an evaporator of the cooling system at a first location of a suction line using one or more sensors communicatively coupled to an expansion valve;
adjusting flow rate of a first portion of refrigerant flowing through a first fluid line of a subcooling heat exchange assembly to a second location of a suction line based on the sensed temperature and the sensed pressure, wherein the subcooling heat exchange assembly comprises the first fluid line and a second fluid line each fluidly coupled to an output of a condenser of the cooling system, wherein adjusting the flow rate of the first portion of refrigerant comprises adjusting a position of the expansion valve to a more open position when the temperature and pressure of the refrigerant output from the evaporator at the first location increase, wherein the first location is downstream of the second location, and wherein the flow rate of the first portion of refrigerant increases when the expansion valve is opened to the more open position; and
affecting an adjustment of a choked mass flow rate of the refrigerant through a plurality of parallel capillary tubes, wherein the plurality of capillary tubes is fluidly coupled to the output of the second fluid line of the subcooling heat exchange assembly.

14. The method of claim 13 , wherein the temperature and the pressure of the refrigerant output from the evaporator increases when an operating capacity of a compressor of the cooling system increases above an expected operating capacity, wherein the compressor is configured to drive circulation of the refrigerant through the cooling system, and wherein the subcooling heat exchange assembly is configured to affect an increase in the choked mass flow rate of refrigerant through the plurality of parallel capillary expansion tubes when the operating capacity of the compressor increases above the expected operating capacity to facilitate substantially uniform distribution of refrigerant mass flow through the plurality of capillary expansion tubes.

15. The method of claim 14 , wherein each of the plurality of parallel capillary tubes is flu

Assignees

• Johnson Controls Tech Co

Inventors

• Kester Douglas A
• Caskey Curtis W
• Spitzer James K
• Yelamanchili Chandra
• Mislak Nicholas P
• Karkhanis Rajiv K

Classifications

• F25B43/006

  Accumulators · CPC title

• F25B2700/195

  of the condenser · CPC title

• F25B2700/21163

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

• F25B49/02

  for compression type machines, plants or systems · CPC title

• F25B2700/13

  Mass flow of refrigerants · CPC title