US20060225870A1

US20060225870A1 - Cooling apparatus, system, and associated method

Info

Publication number: US20060225870A1
Application number: US11/103,678
Authority: US
Inventors: Ching Tsai; Julian Prabhu; Frank Shen
Original assignee: Boeing Co
Current assignee: Boeing Co
Priority date: 2005-04-12
Filing date: 2005-04-12
Publication date: 2006-10-12

Abstract

The present invention provides a cooling apparatus, system, and associated method. The cooling apparatus includes an insulating material, and a heat transfer device at least partially embedded within the structure material. The cooling apparatus also includes a diamond composite sheet positioned adjacent to the structure material, wherein the diamond composite sheet is in thermal communication with the heat transfer device.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention is related to a cooling system and, more particularly, to a cooling system employing a thermal radiator for removing waste heat from one or more heat sources.
2. Description of Related Art
The trend of current and future spacecraft is loaded toward high power electronics that generate increasing amounts of waste heat. High performance thermal radiators are required to compensate for this additional waste heat. Thermal radiators generally include a conductive material positioned adjacent to a heat source that conducts heat generated from the heat source to a heat pipe, heat sink, or other heat transfer device. In order to reduce the thermal gradient between the heat source and the heat transfer device, thermal radiators preferably minimize the thermal resistance through the heat transfer path.
Highly conductive materials are used to efficiently and effectively transfer heat away from the heat source and to the heat transfer device. Currently, aluminum alloys are the most commonly used conductive materials in thermal radiators. However, it is well known that diamond is the most effective heat conductor. As a result of this advantage, attempts have been made to incorporate diamond to conduct heat from the heat source. For example, U.S. Patent Application Publication No. 20040175875 to Sung (“Sung”) discloses a diamond composite heat spreader for semiconductor applications. The heat spreader produces a variable thermal conductivity gradient by incorporating regions of diamond particulate that are adjacent to heat sources. Diamond films may also be formed adjacent to the diamond particulate regions to increase thermal conductivity adjacent to a heat source. FIGS. 1a and 1b of Sung illustrate that the heat spreader may be positioned between and adjacent to a CPU and heat sink, or the heat spreader could be partially embedded within the heat sink and/or heat source. In addition, FIG. 1c demonstrates that the heat sink may be a heat pipe, and the heat spreader may be positioned in direct contact with the heat pipe to transfer heat from the heat spreader.
Despite utilizing diamond particulates and films to conduct heat from a heat source and to a heat transfer device, improvements are desired to handle the increased amounts of waste heat generated by high powered heat sources. In particular, a thermal radiator that is versatile and capable of being used for large-scale cooling applications beyond the semiconductor industry, such as for spacecraft, is desired.
It would therefore be advantageous to provide an improved thermal radiator for rapidly dissipating increased amounts of waste heat generated by modem electronic systems. In this regard, it would be advantageous to provide a thermal radiator that provides increased heat transfer and lower thermal resistance than conventional thermal radiators. It would also be advantageous to provide a thermal radiator that offers a relatively simple construction of lightweight materials and lower manufacturing cost than conventional thermal radiators.

BRIEF SUMMARY OF THE INVENTION

The invention addresses the above needs and achieves other advantages by providing a thermal radiator that includes a diamond face sheet or a composite diamond face sheet that is positioned proximate to a heat source to efficiently transfer heat away from the heat source and to a heat transfer device, such as a heat pipe. Because the thermal radiator utilizes a diamond sheet or diamond composite sheet, the heat is capable of conducting three-dimensionally to produce a much higher radiator face sheet surface temperature. As a result, the effectiveness of the thermal radiator significantly increases thermal dissipation efficiency, which is beneficial for applications such as spacecraft and satellites.
In one embodiment of the present invention, a cooling apparatus is provided. The cooling apparatus includes an insulating material, and a heat transfer device at least partially embedded within the structure material. The cooling apparatus also includes a diamond composite sheet positioned adjacent to the structure material, wherein the diamond composite sheet is in thermal communication with the heat transfer device. The diamond composite sheet is also typically positioned adjacent to the heat transfer device.
In various aspects of the cooling apparatus, the structure material is an insulating panel, such as carbon foam. The heat transfer device could be, for example, a heat pipe or a liquid cooling tube. In addition, the diamond composite sheet is preferably one of diamond aluminum, diamond silicon, or diamond copper.
In another embodiment of the present invention, an additional cooling apparatus is provided that not only includes a structure material and a heat transfer device at least partially embedded within the structure material, but also a conductive sheet positioned adjacent to the structure material. The conductive sheet is in thermal communication with the heat transfer device, and heat is capable of conducting three dimensionally within the conductive sheet. The conductive sheet is also typically positioned adjacent to the heat transfer device. The conductive sheet typically includes a diamond sheet or a diamond composite sheet of diamond aluminum, diamond silicon, or diamond copper.
In accordance with another aspect of the present invention, a system is provided that includes a heat source thermally coupled to a cooling apparatus (as described above). The heat transfer device is in thermal communication with the heat source and the diamond composite sheet or conductive sheet. The heat transfer device may be capable of transferring heat from the heat source and to the diamond composite sheet.
Furthermore, one aspect of the present invention provides a method for cooling a heat source. The method includes positioning a cooling apparatus having a diamond composite sheet supported by a structure material such that the diamond composite sheet is in thermal communication with the heat source. The method also includes transferring heat away from the heat source by movement of the heat through the diamond composite sheet and a heat transfer device embedded within the structure material. In aspects of the method, the positioning step includes attaching the diamond composite sheet to the structure material and/or the heat transfer device. In addition, the step of transferring could include transferring heat three dimensionally within the diamond composite sheet. The step of transferring could also include transferring heat from the heat source to the diamond composite sheet with the heat transfer device

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
FIG. 1 is an elevation view of a cooling apparatus according to one embodiment of the present invention;
FIG. 2 is a side view of the cooling apparatus shown in FIG. 1;
FIG. 3 is a side view of a cooling system including a heat source in thermal communication with a cooling apparatus, according to one embodiment of the present invention; and
FIG. 4 is a flowchart illustrating a method of cooling a heat source using the cooling apparatus shown in FIGS. 1-2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
With reference to FIGS. 1-2, a thermal radiator 10 in accordance with one embodiment of the present invention is illustrated. The thermal radiator 10 includes a face sheet 12 positioned adjacent to a heat transfer device 14 and a structure material 16. The heat transfer device 14 is embedded within the structure material 16. In use, the thermal radiator 10 and, in particular, the face sheet 12 is in thermal communication with one or more heat transfer devices 14 to remove waste heat from the heat source 18.
The thermal radiator 10 is applicable to a wide range of applications. For example, the thermal radiator 10 could be used for cooling spacecraft, aircraft, satellites, or other systems and applications. As described below, the thermal radiator 10 is capable of rejecting substantial amounts of heat such that the thermal radiator 10 could be used for deep space programs or high speed aircraft that generate large amounts of waste heat. Moreover, the term “thermal radiator,” as used herein, is not meant to be limiting as the thermal radiator could be any suitable cooling apparatus or device including the various components and features disclosed within the present application.
One or more heat sources 18 are associated with the system employing the thermal radiator 10. The heat source 18 could generate waste heat or could become heated through an external source. For example, the heat source 18 could be various vehicle computer, avionics, or other electrical and mechanical components utilized within the system. The thermal radiator 10 and, in particular, the face sheet 12, is in thermal communication with the heat source 18. For instance, as shown in FIG. 3, a heat source 18 is positioned in proximity to the face sheet 12 such that heat generated by the heat source is directly transferred to the face sheet through the heat transfer device 14. For example, the heat source 18 could be positioned approximately 6-8 inches from the thermal radiator 10. However, the heat source 18 may be any number of distances from the thermal radiator 10 and may be positioned at various locations with respect to the thermal radiator, such as behind the thermal radiator as shown in FIG. 3. Moreover, any number of thermal radiators 10 could be used within a system to receive and discharge waste heat generated by the heat sources 18. For example, several thermal radiators 10, configured as panels, could be arranged adjacent to one another and in thermal and/or fluid communication with one another as well as the heat sources 18.
The structure material 16 is typically a foam material that is highly electrically conductive but thermally insulating. For example, the structure material 16 could be carbon foam. The structure material 16 could be a foam panel supporting the face sheet 12 and in direct contact with the heat transfer device 14. Thus, if a foam panel is employed, the panel could include one or more openings for accommodating the heat transfer device 14. As such, the heat transfer device 14 is embedded within, or otherwise surrounded by, structure material 16. Alternatively, the structure material 16 could be applied around the heat transfer device 14 and adjacent to the face sheet 12. Although reference has been made to foam structure material, it is understood that any number of structure materials may be employed with the present invention. For example, the structure material 16 could be fiberglass. In addition, it is understood that the structure material 16 could be positioned directly in contact with the face sheet 12. Furthermore, the structure material 16 is typically an insulating material, however, the structure material need only be capable of supporting the face sheet 12 and heat transfer device 14.
To remove waste heat and avoid any degradation of the performance of the system incorporating one or more heat sources 18, one or more heat transfer devices 14 are positioned within the thermal radiator 10. The heat transfer device 14 could be any suitable device for transferring waste heat. For example, the heat transfer device 14 could be a heat pipe, heat sink, liquid cooling tube, or any other suitable heat transfer device or mechanism that is capable of transferring waste heat from the heat source 18 to the face sheet 12 of the thermal radiator 10. FIG. 1 illustrates that the heat transfer device 14 is an open system, where pipes travel parallel to one another through the structure material 16. As such, the heat transfer device 14 of this illustrated device may be a liquid cooling tube in which the fluid flowing therethrough is in thermal communication with one or more additional heat transfer devices, such as a heat sink such that heat may be transferred from the heat transfer device to the heat sink. For instance, the heat sink could be cooled with air, liquid, or a fan, or the heat sink could be a cold plate, or any other heat sink known to those skilled in the art. In one embodiment, heat carried by the heat transfer device 14 could simply be dissipated into space when the thermal radiator 10 is used with a spacecraft, aircraft, satellite, or similar airborne vehicle or device. Thus, fins could be positioned external to the spacecraft, aircraft, or satellite, and the fins could be in thermal communication with the heat transfer device 14 to dissipate heat into space.
Although FIG. 1 illustrates that the heat transfer device 14 is an open system, it is understood that the heat transfer device could be a closed system. Thus, the heat transfer device 14 could be a pulsating heat pipe (PHP) that is positioned within the structure material 16. The thermal radiator of a closed system 10 could also include a loop heat pipe (LHP) as a thermal transfer device 14. Each of the PHP and LHP, as also known to those skilled in the art, are passive devices that operate under pressure differences caused by heat to force fluid that is heated by a heat source 18 to propagate toward a heat sink or other location where heat is withdrawn from the fluid. In addition, the thermal radiator 10 may utilize various configurations of heat pipes, such as straight, curved, crossing, or any number of configurations for achieving a desired amount of cooling.
The face sheet 12 is a diamond or diamond composite material. For example, the diamond composite face sheet 12 could be diamond aluminum (Dia/Al), diamond silicon (Dia/Si), diamond copper (Dia/Cu), or other types of thermal diamond composites. The diamond composite material is advantageous in that it is highly conductive, is hard, durable, and corrosion resistant, and is generally flat and smooth. Accordingly, the diamond composite material provides increased thermal conductivity relative to conventional conductive materials such as aluminum or copper and is able to more efficiently transfer heat away from a heat source 18.
The face sheet 12 is preferably a sheet of material that is positioned directly adjacent to, and in thermal communication with, the heat transfer device 14 and structure material 16. Therefore, the heat source 18, face sheet 12, heat transfer device 14, and structure material 16 are capable of being in thermal communication with one another. It is understood that the heat transfer device 14 could be positioned proximate (i.e., not in direct contact with the face sheet 12) to the face sheet and still be in thermal communication.
The diamond composite face sheet 12 is capable of receiving heat from a heat transfer device 14 and, then, transferring heat three dimensionally. As a result, the orientation of the face sheet 12 does not affect its conductive properties. This property enables the face sheet 12 to be applicable for systems that consistently change orientation, such as rotating satellites. Consequently, the satellite does not have to be repositioned to ensure that the thermal radiator 10 is operating effectively.
In one embodiment, the face sheet 12 is approximately 70 mm (length)×70 mm (width)×3 mm (thickness) in dimension. However, it is understood that the face sheet 12 could be any number of dimensions to accommodate various thermal radiators 10, where the size is generally chosen to conduct a sufficient amount of heat from the heat transfer device 16 and heat source 18 to maintain a desired operating temperature. Thus, the face sheet 12 and thermal radiator 10 are customizable for different applications, especially where the amount of waste heat is known or capable of being determined. In addition, the face sheet 12 could be non-planar and/or unsmooth to accommodate various contours and surfaces.
The face sheet 12 is typically attached to the heat transfer device 14 and structure material 16 with an adhesive, weld, solder, or similar technique. As shown in FIGS. 1-2, a single face sheet 12 and heat transfer device 14 are shown. However, it is understood that there could be multiple face sheets 12 stacked on one another and directly adjacent to the heat transfer device 14 and structure material 16.
The flowchart depicted in FIG. 4 illustrates the general operation of a thermal radiator 10. Typically, the thermal radiator 10 would be positioned proximate to one or more heat sources 18 such that the radiator and heat source are in thermal communication and, more particularly, such that the face sheet 12, heat transfer device 14, and heat source 18 are in thermal communication (block 20). When the heat source 18 generates waste heat, the heat transfer device 14 will transfer the waste heat from the heat source (block 22). The heat transfer device 14, which is also in thermal communication with the face sheet 12 and structure material 16, transfers heat to the face sheet (block 24). The heat transfer device 14 and face sheet 12 then remove waste heat from the thermal radiator 10 (block 26).
The various embodiments of the present invention provide several advantages. The diamond composite face sheet is capable of achieving a higher temperature than conventional conductive materials. A high intensity of radiative heat flux dissipation for the thermal radiator 10 can be achieved due to this high temperature and the fact that the total energy emitted is proportional to absolute radiator panel surface temperature to the fourth power. The thermal radiator 10 is also lighter and more compact than conventional thermal radiators. Furthermore, heat is capable of conducting three-dimensionally through the diamond face sheet or diamond composite face sheet such that the orientation of the thermal radiator 10 does not affect the cooling capability of the radiator. Because the effectiveness of the thermal radiator 10 is not dependent on orientation, spacecraft and satellites will benefit from using the thermal radiator.
Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A cooling apparatus comprising:

an insulating material;

a heat transfer device at least partially embedded within the structure material; and

a diamond composite sheet positioned adjacent to the structure material, wherein the diamond composite sheet is in thermal communication with the heat transfer device.

2. The apparatus according to claim 1, wherein the structure material comprises an insulating panel.

3. The apparatus according to claim 2, wherein the insulating panel comprises a carbon foam.

4. The apparatus according to claim 1, wherein the heat transfer device comprises a heat pipe.

5. The apparatus according to claim 1, wherein the heat transfer device comprises a liquid cooling tube.

6. The apparatus according to claim 1, wherein the diamond composite sheet is comprised of one of diamond aluminum, diamond silicon, and diamond copper.

7. The apparatus according to claim 1, wherein the diamond composite sheet is positioned adjacent to the heat transfer device.

8. A cooling apparatus comprising:

an insulating material;

a conductive sheet positioned adjacent to the structure material, wherein the conductive sheet is in thermal communication with the heat transfer device, and wherein heat is capable of conducting three dimensionally within the conductive sheet.

9. The apparatus according to claim 8, wherein the conductive sheet comprises one of a diamond sheet and a diamond composite sheet.

10. The apparatus according to claim 9, wherein the diamond composite sheet comprises of one of diamond aluminum, diamond silicon, and diamond copper.

11. The apparatus according to claim 8, wherein the conductive sheet is positioned adjacent to the heat transfer device.

12. A cooling system comprising:

at least one heat source;

a cooling apparatus thermally coupled to the heat source, the cooling apparatus comprising:

a structure material;

a diamond composite sheet positioned adjacent to the structure material, wherein the heat transfer device is in thermal communication with the heat source and the diamond composite sheet.

13. The system according to claim 12, wherein the diamond composite sheet comprises of one of diamond aluminum, diamond silicon, and diamond copper.

14. The system according to claim 12, wherein the diamond composite sheet is positioned adjacent to the heat transfer device.

15. The system according to claim 12, wherein the heat transfer device is capable of transferring heat from the heat source and to the diamond composite sheet.

16. A cooling system comprising:

at least one heat source;

a structure material;

a conductive sheet positioned adjacent to the structure material, wherein the heat transfer device is in thermal communication with the heat source and the conductive sheet, and wherein heat is capable of conducting three dimensionally within the conductive sheet.

17. The system according to claim 16, wherein the conductive sheet comprises one of a diamond sheet and a diamond composite sheet.

18. The system according to claim 17, wherein the diamond composite sheet comprises one of diamond aluminum, diamond silicon, and diamond copper.

19. A method for cooling a heat source:

positioning a cooling apparatus having a diamond composite sheet supported by a structure material such that the diamond composite sheet is in thermal communication with the heat source; and

transferring heat away from the heat source by movement of the heat through the diamond composite sheet and a heat transfer device embedded within the structure material.

20. The method according to claim 19, wherein positioning comprises attaching the diamond composite sheet to at least one of the structure material and heat transfer device.

21. The method according to claim 19, wherein transferring comprises transferring heat three dimensionally within the diamond composite sheet.

22. The method according to claim 19, wherein transferring comprises transferring heat from the heat source to the diamond composite sheet with the heat transfer device.