US20120000240A1

US20120000240A1 - Refrigerant cooling device

Info

Publication number: US20120000240A1
Application number: US12/829,102
Authority: US
Inventors: Brent Alden Junge; Stephanos Kyriacou
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2010-07-01
Filing date: 2010-07-01
Publication date: 2012-01-05

Abstract

A refrigeration system for an appliance includes a compression stage, a condenser stage, and an evaporation stage. The condenser stage includes a first condenser coupled to the compression stage and a pressure restriction device coupled between the first condenser and the evaporation stage.

Description

BACKGROUND OF THE INVENTION

The present disclosure generally relates to refrigeration systems, and more particularly to final condensing devices employed in refrigeration systems.
Compressor-run refrigeration systems typically include a compressor, a condenser, a metering device and an evaporator. These systems consume contribute to the consumption of electrical energy use. Since these systems often operate at relatively high ambient temperatures, a significant amount of energy is generally required to convert the liquid coolant flowing from the condenser to the evaporator into a gas, and to raise the pressure of the gas from the low side pressure found in the evaporator to the high side pressure found in the condenser. New regulations and consumer demand encourage the development of lower energy-use appliances.
Various approaches to energy-saving appliances have been developed including the use of vacuum panels that decrease the heat entering the refrigerator. Sub-coolers are commonly used in larger refrigeration systems to reduce the heat of the liquid refrigerant flowing from the condenser into the evaporator, thereby increasing heat absorption and decreasing the amount of energy use required. However, the use of vacuum panels requires the addition of expensive parts, thus increasing the total cost of the appliance for a consumer.
Household consumer appliances often employ the use of the simple capillary tube type of expansion or metering device. Capillary tubes function as restriction devices or metering devices by forcing the refrigerant entering the tube to be mostly liquid. However, the capillary tube, which regulates the flow of the refrigerant, occasionally allows a bubble of refrigerant vapor to enter. This means that there is at least occasionally two-phase refrigerant, liquid and gas, entering the capillary tube. When a vapor bubble enters the capillary tube, the refrigerant mass flow is greatly decreased while the low-density bubble travels the length of the tube. When the refrigerant is sub-cooled, it is all liquid and hard to control using a capillary tube. The presence of vapor in the line or tube from the condenser to the evaporator can significantly decrease the efficiency of the system by decreasing the amount of liquid passing to the evaporator. This can make it difficult to achieve sub-cooling repeatedly in a capillary type of system, such as a refrigerator for example.
A sub-cooler, although also used to cool the refrigerant entering an evaporator and produce a thermodynamic advantage, is more suited for use in an expansion valve system used in commercial industries. When used in a capillary system, such as in a household refrigerator where capillary tubes are used as the expansion devices, a two-phase mixture of refrigerant can result, which cannot be sub-cooled. Sub-coolers can also be relatively expensive making them less attractive for household consumer appliance applications.
It would be advantageous to achieve the benefits of a sub-cooler using a technique that is suitable for a capillary tube system.
Accordingly, it would be desirable to provide a system that addresses at least some of the problems identified above while also being cost effective and easily adaptable to household appliances.

BRIEF DESCRIPTION OF THE INVENTION

As described herein, the exemplary embodiments overcome one or more of the above or other disadvantages known in the art.
One aspect of the exemplary embodiments is directed to a refrigeration system for an appliance. In one embodiment the refrigeration system comprises a compression stage, a condenser stage, and an evaporation stage coupled to the compression stage. The condenser stage includes a first condenser coupled to the compression stage, and a pressure restriction device coupled between the first condenser and the evaporation stage.
Another aspect of the exemplary embodiments relates to a refrigeration system for an appliance. In one embodiment, the refrigeration system includes a compression stage, a condenser stage, and an evaporation stage. The condenser stage includes a first condenser coupled to the compression stage, a final condenser coupled to the evaporation stage and a pressure restriction device is coupled between the first condenser and the final condenser.
These and other aspects and advantages of the exemplary embodiments will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. In addition, any suitable size, shape or type of elements or materials could be used.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1A is a schematic diagram of an exemplary refrigeration system incorporating aspects of the disclosed embodiments.

FIG. 1B is a schematic diagram of another exemplary refrigeration system incorporating aspects of the disclosed embodiments.

FIG. 2 illustrates an exemplary appliance incorporating aspects of the disclosed embodiments.

FIG. 3 partially and schematically shows some of the components of the refrigerator of FIG. 2, with one fresh food compartment door open and the other being removed and the door for the sub-compartment and the drawer/door for the freezer compartment being removed.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION

Referring to FIG. 1A, an exemplary refrigeration system 100 for an appliance incorporating aspects of the disclosed embodiments is illustrated. The aspects of the disclosed embodiments provide a restriction device between the condenser and final condenser in a capillary system to reduce the pressure of the refrigerant leaving the condenser. This can drop the saturation temperature of the refrigerant, which can result in an increase in cooling capacity and a reduction in energy usage. Although the aspects of the disclosed embodiments will generally be described herein with respect to a refrigerator, in alternate embodiments, the aspects of the disclosed embodiments can be applied to any refrigeration system utilizing a capillary tube expansion system, including for example, a household air conditioning system.
As is shown in FIG. 1A, the refrigeration system 100 includes an evaporation stage 12, a compression stage 14 disposed downstream of the evaporation stage 12 and a condenser stage 16 disposed downstream of the compression stage 14. The refrigeration system 100 includes therein a working medium (i.e., the refrigerant). The compression stage 14 is generally configured to compress the refrigerant received in a liquid low-pressure vapor state from the evaporation stage 12 into a high-pressure gas vapor. The compression stage 14 can generally comprise any conventional compressor unit. From the compression stage 14, the high-pressure refrigerant gas passes to the condenser stage 16 where the refrigerant is condensed and heat is rejected to the ambient air. In this embodiment, the condenser stage 16 includes an air-cooled condenser, but the system 100 can also utilize water cooled units or any other type of conventional condenser unit. The low-pressure liquid refrigerant from the condenser stage travels to the evaporation stage 12, where the low-pressure liquid refrigerant is vaporized to absorb heat. The evaporation stage 12 is coupled to and between the compression stage 14 and the condenser stage 16 in a suitable manner, while the compression stage 14 is coupled to the condenser stage 16 in a suitable manner.
In one embodiment, the evaporation stage 12 includes an evaporator 102 and the compression stage 14 includes a compressor 104. As is shown in FIG. 1A, the condenser stage 16 includes a condenser 106, a restriction device 108 and a final condenser 110, suitably coupled together. In one embodiment, the liquefied refrigerant passes from the condenser 106 through line 107 to a restriction device 108. The restriction device 108 is placed after the condenser 106 and before the final condenser 110. The restriction device 108 is configured to reduce the pressure of the refrigerant leaving the condenser 106 and entering the final condenser 110. This will reduce the saturation temperature of the refrigerant down from the condensing temperature, which is typically in the range of approximately 10 to 15 degrees Fahrenheit above the ambient temperature. In one embodiment, the restriction device 108 comprises a piece of capillary tubing. Generally, the restriction device 108 has a very short length, such as in the range of approximately 0.5 to 2.0 inches, and preferably approximately one (1) inch. An inner diameter of the restriction device 108 can be in the range of approximately 0.025 to 0.045 inches, and preferably 0.035 inches or less. In alternate embodiments, the restriction device 108 can be of any suitable size that will enable the reduction of the temperature of the refrigerant leaving the condenser 106 and entering the final condenser 110 by approximately 10 to 15 degrees Fahrenheit in saturation pressure, without concern for a mixture of liquid and vapor refrigerant entering the evaporation stage 102. The restriction device 108 is generally made from a heat conducting material, such as copper or steel, for example.
In one embodiment, the system 100 can also include a condenser loop 120. The condenser loop 120 can be placed downstream of the condenser 106 and before the restriction device 108. The condenser loop 120 generally comprises a length of tubing that is placed near cold areas of the refrigerator doors to keep these areas from sweating, particularly when humidity is high. Although the condenser loop 120 is shown in FIGS. 1A and 1B, it is not intended to limit the scope of the disclosed embodiments.
A refrigerant final condenser 110 is placed after the condenser 106 to further reduce the temperature of the refrigerant prior to entering the evaporator 102. The final condenser 106 is generally compatible with capillary tube type expansion devices typically found in consumer appliances, such as household refrigerators.
Typically, the temperature of the refrigerant exiting the condenser 106 will be in the range of approximately 100 to 105 degrees Fahrenheit when the appliance is operated in a 90 degree Fahrenheit ambient. In this situation, the temperature of the refrigerant exiting the final condenser 110 will be approximately 90 degrees Fahrenheit. By adding the restriction device 108 between the condenser 106 and the final condenser 110, the saturation temperature of the refrigerant is reduced from the condensing temperature down to the ambient temperature. This allows the refrigerant to be condensed by the final condenser 110 at a temperature that is approximately the ambient temperature.
The refrigerant passes through line 109 to final condenser 110 where it is cooled before the refrigerant passes through line 111 to the evaporator 102. The low-pressure liquid line 111 extends from the final condenser 110 to the evaporator 102 where the refrigerant is vaporized to absorb heat. In one embodiment, the line 111 is a length of capillary tubing. The length of the line 111 can be up to approximately 5 feet, and have, for example, an inner diameter in the range of approximately 0.020 to 0.032 inches or larger. In accordance with the aspects of the disclosed embodiment, when the cooled refrigerant enters the evaporator 102 from the final condenser 110, it is at a lower enthalpy. This lower enthalpy allows the refrigerant to absorb more heat in the evaporator 102. Because the conditions at the compressor 104 are unchanged, the compressor power is not changed. However, the cooling capacity is increased, resulting in a decrease in overall energy usage.
FIG. 1B illustrates another example of a cooling system incorporating aspects of the disclosed embodiments. In comparison to FIG. 1A, in this embodiment, the restriction device 108 is part of, or comprises the final condenser 118 shown in FIG. 1B. The final condenser 118 shown in FIG. 1B comprises a section of small diameter tubing, such as a capillary tube, that is suitably sized to provide the required pressure drop to achieve a reduction in temperature. Generally, a pressure drop of approximately 20 psi will reduce the saturation temperature of R-134 type refrigerant approximately 10 degrees Fahrenheit, from approximately 100 degrees Fahrenheit to approximately 90 degrees Fahrenheit. In one embodiment, the final condenser 118 comprises a tube have a internal diameter of approximately 0.08 inches, or generally in the range of approximately 0.02 inches to 0.10 inches. A length of the tube can be in the range of approximately ten to twenty feet.
Referring to FIGS. 2 and 3, an exemplary refrigerator 200 incorporating aspects of the disclosed embodiments is illustrated. The refrigerator 200 has a main body 202 which defines therein a first, upper, fresh food compartment 204 with a frontal access opening 204A and a second, lower, freezer compartment 206 with a frontal access opening 206A. The fresh food compartment 204 and the freezer compartment 206 are arranged in a bottom mount configuration where the fresh food compartment 204 is disposed or positioned above the freezer compartment 206. In alternate embodiments, any suitable arrangement of a fresh food compartment and a freezer compartment can be utilized, other than including a bottom mount configuration. The fresh food compartment 204 In FIG. 2 is shown with two French doors 208 and 210. However, a single door can be used instead of the two doors 208, 210. The freezer compartment 206 can be closed by a drawer or a door 212 in a known or suitable manner.
The main body 202 of the refrigerator 200 includes a top wall 230 and two sidewalls 232. The top wall 230 connects the sidewalls 232 to each other at the top ends thereof. A mullion 234, best shown in FIG. 3, connects the two sidewalls 232 to each other and separates the fresh food compartment 204 from the freezer compartment 206. The main body 202 also includes a bottom wall 234, which connects the two sidewalls 232 to each other at the bottom ends thereof, and a back wall 235.
FIG. 3 illustrates one embodiment of the refrigeration system 100 of FIG. 1 incorporated in the refrigerator 200. The sealed system 100 includes an evaporator 102 disposed in the freezer compartment 206, a compressor 104 disposed downstream of the evaporator 102 and outside of the freezer compartment 206, a condenser 106 disposed downstream of the compressor 104, a restriction device 108 disposed downstream of the condenser 106, and a final condenser 110 disposed downstream of the restriction device 108.
In one embodiment, the final condenser 110 is disposed on or embedded in the cabinet portion 242 of the refrigerator body 202. The cabinet 242 is generally a large heat sink that is approximately at the ambient temperature and can be used to cool refrigerant in the final condenser 110. Since the restriction device 108 reduces the temperature of the refrigerant down to approximately the ambient temperature, in one embodiment, the refrigerant will be condensed by the final condenser 110 at a temperature that is approximately the ambient temperature. Although the final condenser 110 is shown disposed in the cabinet portion 242 of the freezer compartment 206, in alternate embodiments, the final condenser 110 can be disposed on or in a cabinet portion 252 of the fresh food compartment 204, on the back portion 235 of the main body 202 or other suitable heat exchanging plate in the refrigerator 200. This allows the final condenser 110 to bring the temperature of the refrigerant down to approximately that of the refrigerator body 202, which is approximately ambient temperature.
The aspects of the disclosed embodiments utilize a restriction device between the condenser and evaporator to reduce the saturation temperature of the refrigerant to approximately the ambient temperature in a capillary tube refrigeration system. A relatively short length of capillary tubing or other restriction is used to reduce the pressure of the refrigerant leaving the condenser. The restriction can be part of the final condenser or a separate restriction device that is coupled between the condenser and final condenser. This reduction in pressure can result in a reduction of the temperature of the refrigerant leaving the condenser to a temperature that is approximately the ambient temperature, which can increase the cooling capacity of the refrigerant entering the evaporator. In some instances, this can result in a reduction of approximately 10-15 degrees Fahrenheit, which can reduce energy usage and generate cost savings. In one embodiment, an estimated 5% reduction in energy usage can be anticipated.
Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to the exemplary embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

1. A refrigeration system for an appliance comprising:

a compression stage;

a condenser stage; and

an evaporation stage coupled to the compression stage,

wherein the condenser stage comprises:

a first condenser coupled to the compression stage; and

a pressure restriction device coupled between the first condenser and the evaporation stage.

2. The refrigeration system of claim 1, wherein the pressure restriction device comprises a capillary tube.

3. The refrigeration system of claim 2, wherein an inner diameter of the capillary tube is substantially 0.08 inches.

4. The refrigeration system of claim 1, wherein the restriction device is configured to reduce the pressure of a refrigerant leaving the first condenser and entering the evaporator.

5. The refrigeration system of claim 1, wherein the restriction device is configured to reduce a saturation temperature of refrigerant flowing from the first condenser to the evaporator from a condensing temperature to an ambient temperature level.

6. The refrigeration system of claim 1, further comprising a final condenser coupled to the evaporation stage and wherein the pressure restriction device is coupled between the first condenser and the final condenser.

7. The refrigeration system of claim 6, wherein an inner diameter of the capillary tube is substantially 0.035 inches.

8. The refrigeration system of claim 6, wherein the final condenser is attached to a heat sink of the appliance.

9. The refrigeration system of claim 8, wherein the heat sink comprises a portion of a cabinet for the appliance.

10. The refrigeration system of claim 1, further comprising a capillary tube coupling the final condenser to the evaporation stage.

11. The refrigeration system of claim 1, wherein the appliance is a refrigerator.

12. The refrigeration system of claim 1, wherein the appliance is a household air conditioning unit.

13. A refrigeration system for an appliance comprising:

a compression stage;

a condenser stage; and

an evaporation stage;

wherein the condenser stage comprises:

a first condenser coupled to the compression stage;

a final condenser coupled to the evaporation stage; and

a pressure restriction device coupled between the first condenser and the final condenser.

14. The refrigeration system of claim 13, wherein the pressure restriction device comprises a capillary tube.

15. The refrigeration system of claim 14, wherein a length of the capillary tube is in the range of 0.5 to 1.5 inches.

16. The refrigeration system of claim 15, wherein an inner diameter of the capillary tube is substantially 0.035 inches.

17. The refrigeration system of claim 16, wherein the restriction device is configured to reduce the pressure of a refrigerant leaving the first condenser and entering the final condenser.

18. The refrigeration system of claim 13, wherein the restriction device is configured to reduce a saturation temperature of refrigerant flowing from the first condenser to the final condenser from a condensing temperature to an ambient temperature level.