US20090266084A1

US20090266084A1 - Thermoelectric device based refrigerant subcooling

Info

Publication number: US20090266084A1
Application number: US11/991,332
Authority: US
Inventors: Rakesh Radhakrishnan; Xiaomei Yu; Gregory M. Dobbs; David Tew; Michael K. Sahm; Chung-Yi Tsai
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2005-08-29
Filing date: 2005-08-29
Publication date: 2009-10-29
Also published as: CA2620391A1; CN101297167B; WO2007027171A1; EP1920200A4; EP1920200A1; HK1125692A1; CN101297167A

Abstract

A subcooler (15) for a vapor compression cycle having a refrigerant. The subcooler (15) including a conduit (45) and one or more thermoelectric modules (17). The conduit (45) being in fluid communication with the vapor compression cycle for flow of the refrigerant therethrough. Each of the one or more thermoelectric modules (17) has a cold side in thermal communication with an inner volume of the conduit (45) for subcooling the refrigerant.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates generally to vapor compression cycles and, more particularly, to a method and apparatus for subcooling vapor compression cycles, chilled water coils in air handlers, fan coils, and the like.
2. Description of the Related Art
Refrigerant subcooling to enhance the performance of vapor compression cycles is known. Prior approaches to refrigerant subcooling generally involved the use of mechanical subcooling or suction line heat exchangers. Mechanical subcooling can involve the use of a secondary vapor compression loop requiring additional equipment to the existing system, including a compressor and an expansion valve. Suction line heat exchangers can provide enhanced performance and reduced cost, but they require the use of a secondary liquid, chilled water, to subcool the refrigerant.
Moreover, mechanical subcooling suffers from the drawbacks of requiring numerous components leading to increased maintenance and decreased reliability; provides noisy operation and relatively slow cooling leading to transients (e.g., cycling) and inaccurate temperature control; and can be inefficient.
Accordingly, there is a need for an improved subcooler that does not require the need for a secondary loop or a secondary liquid. The method and apparatus of the present invention avoids the need for a secondary loop or a secondary liquid through the use of a thermoelectric subcooler.
It is an object of the present invention to provide fast acting cooling to minimize transients and fine tune temperature control.
It is another object to decrease evaporator coil temperature and improve coil latent capacity for humidity control.
It is yet another object of the present invention to reduce added equipment to increase reliability and reduce noise.
It is still another object of the present invention to provide energy benefits with or without increased humidity control benefits.

SUMMARY OF THE INVENTION

In one aspect, a subcooler for a vapor compression cycle having a refrigerant is provided. The subcooler comprises a conduit and one or more thermoelectric modules. The conduit being in fluid communication with the vapor compression cycle for flow of the refrigerant therethrough. Each of the one or more thermoelectric modules has a cold side in thermal communication with an inner volume of the conduit for subcooling the refrigerant.
In yet another aspect, a vapor compression system comprising a compressor, a condensor, and an evaporator connected to each other via a conduit and a subcooler is provided. The subcooler has one or more thermoelectric modules connected to the conduit, wherein each of the one or more thermoelectric modules has a cold side in thermal communication with an inner volume of the conduit for subcooling refrigerant circulating therethrough.
In yet another aspect, a method of subcooling a vapor compression cycle is provided. The method comprises providing a conduit for flow of a refrigerant that is in fluid communication with a compressor, a condenser, and an evaporator, and thermoelectrically subcooling an inner volume of the conduit through conduction by a plurality of thermoelectric modules each having a cold side in thermal communication with the inner volume of the conduit and a warm side in thermal isolation from the inner volume.
Each of the one or more thermoelectric modules can have a warm side in thermal isolation from the inner volume of the conduit. The one or more thermoelectric modules can be embedded in the conduit, and the cold side can directly contact the refrigerant. The one or more thermoelectric modules can further comprise a secondary heat exchanger for indirect heat exchange with refrigerant. The one or more thermoelectric modules can comprise a thermoelectric heat exchanger. The thermoeletric heat exchanger can be an air or liquid thermoelectric heat exchanger. The one or more thermoelectric modules can be connected to an outer surface of the conduit and in thermal communication with the refrigerant. The subcooler can further comprise a fan that provides air flow in thermal communication with a warm side of the one or more thermoelectric modules.
The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a vapor compression cycle having a thermoelectric subcooler of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, an exemplary embodiment of a vapor compression cycle generally referred to by reference numeral 10 is illustrated. Vapor compression cycle 10 uses a thermoelectric subcooler 15 to subcool refrigerant of the vapor compression cycle 10. Subcooler 15 may be used for vapor compression cycles such as, for example, supermarket display cases having low coefficient of performance (COPs), e.g., less than 3, as well as any other types of refrigeration cycles of large or small scale. Moreover, chilled water coils in air handlers or fan coils may also be precooled when a transient change in their cooling or humidity removal performance is warranted.
Subcooler 15 may be used in any known vapor compression cycle. Vapor compression cycles known in the art generally include components such as, for example, a compressor 20, an evaporator 25, a condenser 30, and a thermostatic or thermal expansion valve 35. In the exemplary embodiment of FIG. 1, the refrigerant flows through a first conduit 40 from compressor 20 to condenser 30 as represented by arrow 42. Condenser 30 is an air or water cooled condenser that condenses the refrigerant. The refrigerant exits condenser 30 to a second conduit 45 as represented by arrow 44. Subcooler 15 is connected to second conduit 45. Subcooler 15 thermoelectrically subcools the refrigerant as the refrigerant circulates through second conduit 45 from condenser 30. Third conduit 47 connects subcooler 15 to thermal expansion valve 35. The refrigerant circulates through third conduit to thermal expansion valve 35 as represented by arrow 46. Thermal expansion valve 35 decreases a pressure of the refrigerant to a mixed liquid and vapor. The the refrigerant enters evaporator 25 from fourth conduit 48 as represented by arrow 49. Evaporator 25 substantially vaporizes the liquid by heat transfer provided from a refrigerated space 75. A rejection space 70 is underneath evaporator 25 so that heat from evaporator 25 is not rejected to refrigerated space 75. The refrigerant exits evaporator 25 to a fifth conduit 50 as represented by arrows 51. The refrigerant enters compressor 20 from fifth conduit 50. Compressor 20 compresses the refrigerant and completes vapor compression cycle 10.
Subcooler 15 may have one or more thermoelectric modules 17. Thermoelectric modules 17 produce cooling using electrical energy provided to the module by an energy source 18. Thus, thermoelectric modules 17 can be directly attached to second conduit 45 to eliminate a need for a liquid-liquid heat exchanger, secondary liquid, or secondary loop.
Thermoelectric modules 17 may be embedded in second conduit 45 so that a cold side or face is facing inwardly into an inner volume of second conduit 45 and a warm side or face is facing away from the inner volume of second conduit 45. The cold side of each of the thermoelectric modules 17 is in thermal contact with the inner volume of second conduit 45 to provide contact cooling of the refrigerant, while the warm side is in thermal isolation from the inner volume of second conduit 45.
Thermoelectric modules 17 may comprise a thermoelectric heat exchanger using any known refrigerant. Air or liquid may be pumped in the thermoelectric heat exchanger to absorb heat from the refrigerant in second conduit 45. Alternatively, thermoelectric modules 17 may have a secondary heat exchanger for indirect heat exchange with the refrigerant. The particular heat exchanger can be varied based upon the particular cooling needs or dehumidification and other factors related to vapor compression cycle 10.
Thermoelectric modules 17 may also be connected onto an outer surface of second conduit 45 so that a cold side or face is facing inwardly into an inner volume of second conduit 45 and a warm side or face is facing away from the inner volume of second conduit 45. The cold side of each of the thermoelectric modules 17 is in thermal communication with the inner volume of second conduit 45 to provide cooling of the refrigerant, while the warm side is in thermal isolation from the inner volume of second conduit 45. To further improve the cooling efficiency, a fan 19 circulates air about the exterior or outer surface of second conduit 45 so as to provide air in fluid communication with the warm side of the thermoelectric modules 17 to remove or reject heat from the warm side.
Through conduction, the cold side of each of thermoelectric modules 17 cools the refrigerant, which is being circulated through second conduit 45. Second conduit 45 can be made of thermally conductive materials, however, the material can be varied based upon the particular cooling needs and other factors related to vapor compression cycle 10. The number of thermoelectric modules 17 that are used in second conduit 45 can be varied based upon the particular cooling needs and other factors related to the subcooler 15. The particular number of thermoelectric modules 17, as well as the structure or method of making the inner surface or inner portion of second conduit 45 thermally conductive, can be varied based upon the particular cooling needs and other factors related to the display vapor compression cycle 10. Thus, the use of thermoelectric module 17 avoids the need for a secondary liquid or secondary loop, reduces added equipment as compared with mechanical subcoolers, provides fast acting thermoelectric cooling to minimize transients and provide fine tuned temperature and/or humidity control, increased reliability and reduced noise over mechanical subcooling, and also provides energy benefits.
The particular type, including materials, dimensions and shape, of thermoelectric modules 17 that are utilized can vary according to the particular needs of the subcooler 15. Preferably, the dimensions and shape of the cold side and the warm side of the thermoelectric modules 17 maximize thermal contact or communication, e.g., surface area, between second conduit 45 and the cold side, as well as between the air outside of second conduit 45 and the warm side.
The particular structure or method of providing energy source 18 to thermoelectric modules 17 can be varied according to the particular needs of subcooler 15. Thermoelectric modules 17 may be a thermoelectric device powered directly by a DC source, such as, for example, batteries, a portable fuel cell, photovoltaic, and the like, without need for AC-DC conversion. The subcooler 15 may assure that no gas is left at the end of the condensing phase, thus assuring maximum capacity at the thermostatic or thermal expansion valve 35. The proportional nature of thermoelectric modules 17 may be leveraged for ideal use in systems using proportional control. This can avoid use of solenoid valves that are either fully on or off, e.g., typically found in on-off control systems. The thermoelectric modules 17 can be configured in any flow arrangement with respect to conduit 45 to allow best energy exchange. This arrangement can be in a co-flowing, counter flowing or cross flowing configuration or any other arrangement that suits space and other design issues.
While the instant disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A subcooler for a vapor compression cycle having a refrigerant, the subcooler comprising:

a conduit in fluid communication with the vapor compression cycle for flow of the refrigerant therethrough; and

one or more thermoelectric modules, wherein each of said one or more thermoelectric modules has a cold side in thermal communication with an inner volume of said conduit for subcooling the refrigerant.

2. The subcooler of claim 1, wherein each of said one or more thermoelectric modules has a warm side in thermal isolation from said inner volume of said conduit.

3. The subcooler of claim 1, wherein said one or more thermoelectric modules are embedded in said conduit, and wherein said cold side directly contacts the refrigerant.

4. The subcooler of claim 1, wherein said one or more thermoelectric modules further comprises a secondary heat exchanger for indirect heat exchange with the refrigerant.

5. The subcooler of claim 1, wherein said one or more thermoelectric modules comprise a thermoelectric heat exchanger.

6. The subcooler of claim 5, wherein said thermoeletric heat exchanger is an air or liquid thermoelectric heat exchanger.

7. The subcooler of claim 1, wherein at least one of said one or more thermoelectric modules are connected to an outer surface of said conduit and in thermal communication with said refrigerant.

8. The subcooler of claim 7, further comprising a fan that provides air flow in thermal communication with a warm side of said one or more thermoelectric modules.

9. A vapor compression system comprising:

a compressor, a condensor, and an evaporator connected to each other via a conduit; and

a subcooler having one or more thermoelectric modules connected to said conduit, wherein each of said one or more thermoelectric modules has a cold side in thermal communication with an inner volume of said conduit for subcooling refrigerant circulating therethrough.

10. The vapor compression system of claim 9, wherein each of said one or more thermoelectric modules has a warm side in thermal isolation from said inner volume of said conduit.

11. The vapor compression system of claim 9, wherein said one or more thermoelectric modules are embedded in said conduit to contact cool said refrigerant.

12. The vapor compression system of claim 9, wherein said one or more thermoelectric modules comprise a thermoelectric heat exchanger.

13. The vapor compression system of claim 12, wherein said thermoelectric heat exchanger is an air or liquid thermoelectric heat exchanger.

14. The vapor compression system of claim 9, wherein said one or more thermoelectric modules are connected to an outer surface of said conduit and in thermal communication with said refrigerant.

15. The vapor compression system of claim 14, wherein said subcooler further comprises a fan that provides air flow in thermal communication with a warm side of said one or more thermoelectric modules.

16. A method of subcooling a vapor compression cycle comprising:

providing a conduit for flow of a refrigerant that is in fluid communication with a compressor, a condensor, and an evaporator; and

thermoelectrically subcooling an inner volume of said conduit through conduction by a plurality of thermoelectric modules each having a cold side in thermal communication with said inner volume of said conduit and a warm side in thermal isolation from said inner volume.

17. The method of claim 16, wherein a plurality of thermoelectric modules is cooled via a fan.

18. The method of claim 16, wherein said plurality of thermoelectric modules are embedded in said conduit to contact cool said refrigerant.

19-20. (canceled)