HK1125692B - Subcooler, vapor compression system and subcooling method - Google Patents

Description

Subcooler, vapor compression system and subcooling method

Technical Field

The present invention relates generally to vapor compression cycles and, more particularly, to a method and apparatus for subcooling (or subcooling) a vapor compression cycle, a chilled water coil in an air handling machine, a fan coil, or the like.

Background

It is known to subcool refrigerant to enhance the performance of a vapor compression cycle. Prior art refrigerant subcooling approaches typically involve the use of mechanical subcooling or suction tube heat exchangers. Mechanical subcooling may include the use of a secondary vapor compression loop, but it requires the addition of additional equipment (including a compressor and an expansion valve) to the existing system. Suction tube heat exchangers can provide enhanced performance and reduce cost, but they require sub-cooling of the refrigerant with a secondary liquid (i.e., cooling water).

In addition, mechanical subcooling has the following drawbacks: many components are required, resulting in increased maintenance and reduced stability; provides noisy operation and relatively slow cooling leading to transient conditions (e.g., cycling) and inaccurate temperature control; and may be inefficient.

Accordingly, there is a need for an improved subcooler that does not require a secondary loop or secondary liquid. The method and apparatus of the present invention avoids the need for a secondary loop or secondary liquid by using a thermoelectric subcooler.

It is an object of the present invention to provide fast acting cooling to minimize transient conditions and provide fine tuned temperature control.

It is another object of the present invention to reduce the evaporator coil temperature and improve the humidity control potential of the coil.

It is a further object of the invention to reduce the added equipment to improve stability and reduce noise.

It is another object of the present invention to provide energy benefits with or without humidity control enhancement benefits.

Disclosure of Invention

In one aspect, a subcooler for a vapor compression cycle having a refrigerant is provided. The subcooler includes a conduit and one or more thermoelectric modules. The conduit is in fluid communication with the vapor compression cycle for flowing a 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 another aspect, a vapor compression system includes: a compressor, a condenser and an evaporator connected to each other by pipes, 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 interior volume of the conduit for subcooling a refrigerant flowing therethrough.

In another aspect, a method of subcooling a vapor compression cycle is provided. The method includes providing a conduit for flow of a refrigerant in fluid communication with a compressor, a condenser, and an evaporator, and conductively thermoelectrically subcooling an inner volume of the conduit by a plurality of thermoelectric modules, each of the plurality of thermoelectric modules having a cold side in thermal communication with the inner volume of the conduit and a warm side thermally isolated from the inner volume.

Each of the one or more thermoelectric modules may have a warm side that is thermally isolated from the inner volume of the conduit. One or more thermoelectric modules may be embedded in the conduit, and the cold side may be in direct contact with the refrigerant. The one or more thermoelectric modules may further comprise a secondary heat exchanger to indirectly exchange heat with the refrigerant. The one or more thermoelectric modules may include a thermoelectric heat exchanger. The thermoelectric heat exchanger may be an air or liquid thermoelectric heat exchanger. One or more thermoelectric modules may be attached to an outer surface of the conduit and in thermal communication with the refrigerant. The subcooler may further include a fan to provide an air flow in thermal communication with the warm side of the one or more thermoelectric modules.

The above and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

Drawings

Fig. 1 schematically illustrates a vapor compression cycle having a thermoelectric subcooler of the present invention.

Detailed Description

Referring now to FIG. 1, an exemplary embodiment of a vapor compression cycle, generally designated by the reference numeral 10, is illustrated. The vapor compression cycle 10 uses a thermoelectric subcooler 15 to subcool the refrigerant of the vapor compression cycle 10. Thermoelectric subcooler 15 may be used in vapor compression cycles such as: supermarket exhibits with low coefficient of performance (COP) (e.g. below 3) and any other type of large or small refrigerant cycle. In addition, the cooling water coils or fan coils in the air handler may also be pre-cooled when transient state changes in their cooling or dehumidification performance are warranted.

Subcooler 15 may be used in a known vapor compression cycle. Vapor compression cycles known in the art typically include elements such as: a compressor 20, an evaporator 25, a condenser 30, and a thermostatic or thermal expansion valve 35. In the exemplary embodiment of fig. 1, refrigerant flows from compressor 20 to condenser 30 via first conduit 40, as indicated by arrow 42. The condenser 30 is an air-cooled or water-cooled condenser for condensing the refrigerant. The refrigerant exits the condenser 30 to a second conduit 45 as indicated by arrow 44. Subcooler 15 is connected to second conduit 45. Subcooler 15 thermoelectrically subcools the refrigerant as it flows from condenser 30 through second conduit 45. A third conduit 47 connects subcooler 15 to thermal expansion valve 35. The refrigerant flows through the third conduit to the thermal expansion valve 35 as indicated by arrow 46. The thermal expansion valve 35 reduces the pressure of the refrigerant to obtain a mixed liquid and vapor. The refrigerant enters the evaporator 25 through a fourth conduit 48 as indicated by arrow 49. Evaporator 25 substantially vaporizes the liquid by heat transfer provided from refrigerated space 75. The discharge space (discharge space)70 is located below the evaporator 25 so that heat from the evaporator 25 is not discharged to the refrigerated space 75. The refrigerant exits the evaporator 25 to a fifth conduit 50 as indicated by arrow 51. The refrigerant enters the compressor 20 from the fifth pipe 50. The compressor 20 compresses a refrigerant and completes the vapor compression cycle 10.

Subcooler 15 may have one or more thermoelectric modules 17. Thermoelectric module 17 uses the electrical energy provided to the module by energy source 18 to produce cooling. Thus, the thermoelectric modules 17 may be directly connected to the second conduit 45 to eliminate the need for a liquid-to-liquid heat exchanger, secondary liquid, or secondary loop.

Thermoelectric modules 17 may be embedded in second conduit 45 such that the cold side or face faces inwardly toward the internal volume of second conduit 45 and the warm side or face faces away from the internal volume of second conduit 45. The cold side of each of 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 thermally insulated from the inner volume of second conduit 45.

Thermoelectric module 17 may comprise a thermoelectric heat exchanger using any known refrigerant. Air or liquid may be pumped into the thermoelectric heat exchanger to absorb heat from the refrigerant in the second conduit 45. Alternatively, the thermoelectric module 17 may have a secondary heat exchanger to indirectly exchange heat with the refrigerant. The particular heat exchanger will vary based on the particular cooling or dehumidification requirements and other factors associated with the vapor compression cycle 10.

Thermoelectric modules 17 may also be attached to the outer surface of second conduit 45 such that the cold side or face faces inwardly toward the inner volume of second conduit 45 and the warm side or face faces away from the inner volume of second conduit 45. The cold side of each of thermoelectric modules 17 is in thermal communication with the inner volume of second conduit 45 to provide cooling to the refrigerant, while the warm side is thermally insulated from the inner volume of second conduit 45. To further improve cooling efficiency, fan 19 flows air over or around the outer surface of second duct 45 to provide air in fluid communication with the warm side of thermoelectric module 17 to remove or reject heat from the warm side.

By conduction, the cold side of each of the thermoelectric modules 17 cools the refrigerant flowing through the second conduit 45. The second conduit 45 may be made of a thermally conductive material, however, the material may be varied based on the particular cooling needs or other factors associated with the vapor compression cycle 10. The number of thermoelectric modules 17 used in the second conduit 45 may be varied based on the particular cooling needs or other factors associated with the subcooler 15. The particular number of thermoelectric modules 17 and the structure or method of thermally conducting the inner surface or inner portion of the second conduit 45 may vary based on the particular cooling requirements or other factors associated with the illustrated vapor compression cycle 10. Thus, the use of thermoelectric modules 17 avoids the need for a secondary liquid or secondary loop, reduces added equipment compared to mechanical subcoolers, provides fast acting thermoelectric cooling to minimize transients and provide fine tuned temperature and/or humidity control, increased stability and reduced noise relative to mechanical subcooling, and also provides energy benefits.

The particular type of thermoelectric module 17 utilized (including materials, size and shape) may vary depending on the particular needs of subcooler 15. Preferably, the cold and warm sides of the thermoelectric module 17 are sized and shaped to maximize thermal contact or communication (e.g., surface area) between the second conduit 45 and the cold side and between the air outside the second conduit 45 and the warm side.

The particular structure or method of providing the energy source 18 to the thermoelectric module 17 may vary depending on the particular needs of the subcooler 15. The thermoelectric module 17 may be a thermoelectric device that is directly driven by a direct current power source, such as a battery, portable fuel cell, photovoltaic cell, or the like, such that no ac to dc conversion is required. Subcooler 15 ensures that no gas remains at the end of the condensing phase, thereby ensuring maximum capacity at thermostatic or thermal expansion valve 35. For systems using proportional control, the proportional nature of the thermoelectric modules 17 can be a means to achieve the desired application. This may avoid the use of fully on or fully off solenoid valves, such as commonly found in on-off control systems. The thermoelectric modules 17 may be configured in any flow arrangement relative to the conduit 45 to allow for optimal energy exchange. This arrangement may be a co-flow, counter-flow, or cross-flow configuration, or any other configuration suitable for space or other design issues.

While the present disclosure has been described in connection with one or more exemplary embodiments, those skilled in the art will understand that: various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. 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 disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims (18)

1. A subcooler (15) for a vapor compression cycle having a refrigerant, said subcooler (15) comprising:

a conduit (45) in fluid communication with the vapor compression cycle for flowing the refrigerant therethrough; and

one or more thermoelectric modules (17), wherein 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 by conduction, and a warm side thermally isolated from the inner volume, wherein at least one of the one or more thermoelectric modules (17) is embedded in the conduit (45).

2. The subcooler (15) of claim 1, wherein each of said one or more thermoelectric modules (17) has a warm side that is thermally isolated from said inner volume of said conduit (45).

3. The subcooler (15) of claim 1, wherein said cold side is in direct contact with said refrigerant.

4. The subcooler (15) of claim 1, wherein said one or more thermoelectric modules (17) further comprise a secondary heat exchanger for indirect heat exchange with said refrigerant.

5. The subcooler (15) of claim 1, wherein said one or more thermoelectric modules (17) comprise a thermoelectric heat exchanger.

6. The subcooler (15) of claim 5, wherein said thermoelectric heat exchanger is an air or liquid thermoelectric heat exchanger.

7. The subcooler (15) of claim 1, wherein at least one of said one or more thermoelectric modules (17) is connected to an outer surface of said conduit (45) and is in thermal communication with said refrigerant.

8. The subcooler (15) of claim 7, further comprising a fan (19) to provide an air flow in thermal communication with the warm side of said one or more thermoelectric modules (17).

9. A vapor compression system (10), comprising:

a compressor (20), a condenser (30) and an evaporator (25) connected to each other by pipes (40, 45, 47, 48, 50); and

a subcooler (15) having one or more thermoelectric modules (17) connected to the conduit (45), wherein 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 a refrigerant flowing therethrough, and the one or more thermoelectric modules (17) are upstream of an expansion valve (35).

10. The vapor compression system (10) of claim 9, wherein each of the one or more thermoelectric modules (17) has a warm side that is thermally isolated from the inner volume of the conduit (45).

11. The vapor compression system (10) of claim 9, wherein said one or more thermoelectric modules (17) are embedded in said conduit (45) to contact cool said refrigerant.

12. The vapor compression system (10) of claim 9, wherein the one or more thermoelectric modules (17) comprise a thermoelectric heat exchanger.

13. The vapor compression system (10) of claim 12, wherein the thermoelectric heat exchanger is an air or liquid thermoelectric heat exchanger.

14. The vapor compression system (10) of claim 9, wherein the one or more thermoelectric modules (17) are connected to an outer surface of the conduit (45) and are in thermal communication with the refrigerant.

15. The vapor compression system (10) of claim 14, wherein the subcooler (15) further comprises a fan (19) to provide an air flow in thermal communication with the warm side of the one or more thermoelectric modules (17).

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

providing a conduit (45) for the flow of a refrigerant in fluid communication with the compressor (20), the condenser (30) and the evaporator (25);

thermoelectrically subcooling an inner volume of the conduit (45) by conduction by a plurality of thermoelectric modules (17), each of the plurality of thermoelectric modules (17) having a cold side in thermal communication with the inner volume of the conduit (45) and a warm side thermally isolated from the inner volume; and

contacting the plurality of thermoelectric modules (17) with the inner volume between the condenser (30) and the expansion valve (35).

17. The method of claim 16, wherein the plurality of thermoelectric modules (17) are cooled by a fan (19).

18. The method of claim 16, wherein said plurality of thermoelectric modules (17) are embedded in said conduit (45) to contact cool said refrigerant.