WO2011037578A1

WO2011037578A1 - Heat transfer systems and methods

Info

Publication number: WO2011037578A1
Application number: PCT/US2009/058447
Authority: WO
Inventors: Mark Tracy; Britt Ashcraft; Jefrrey Lev
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2009-09-25
Filing date: 2009-09-25
Publication date: 2011-03-31
Also published as: US20120118540A1

Abstract

Heat transfer apparatuses and systems are provided. A heat transfer apparatus (100) can include a thermal conduit (110) having a first end (120) and a second end (130). The thermal conduit can be disposed at least partially within an electronic device enclosure (140). A non-heat conductive material (150) can be disposed at least partially about at least a portion of the thermal conduit.

Description

Description of the Related Art

[0001 ] Thermal management in compact electronic devices presents significant challenges. As clock rates of central processing units and other integrated circuit based devices increases and the overall footprint of the devices housing those IC based devices decreases, heat rejection from within the enclosure surrounding the electronic device becomes difficult. Heat pipes and vapor chambers are two solutions used to transfer heat from a heat producing device to a heat rejecting device. However, the heat conveyed by heat pipes and vapor chambers can be radiated along the route of the heat pipe, prior to arriving at the heat dissipating device. This radiation can affect components proximate the heat pipe and, in some circumstances can also cause hot spots on the enclosure surrounding the electronic device.

SUMMARY OF THE INVENTION

[0002] A heat transfer apparatus is provided. A heat transfer apparatus can include a thermal conduit having a first end and a second end. The thermal conduit can be disposed at least partially within an electronic device enclosure. A non-heat conductive material can be disposed at least partially about at least a portion of the thermal conduit.

[0003] As used herein, a material referred to as a "non-heat conductive material" can refer to any material having a relatively low coefficient of thermal conductivity, i.e. a thermal insulator. A non-heat conductive material can include any material suitable for preventing conductive heat transmission, convective heat transmission, radiant heat transmission, or any combination thereof. A non-heat conductive material can include rigid materials, semi-rigid materials, or flexible materials. Exemplary non-heat conductive materials can include, but are not limited to, asbestos, carbon fiber, silica, diatomaceous earth, cork, wool, cotton, plastics, fiberglass, mineral wool, polystyrene, combinations thereof, and the like.

[0004] A heat transfer method is also provided. The method can include disposing a non-heat conductive material about at least a portion of a thermal conduit. The thermal conduit can be a hollow, sealed member having a first end and a second end. The method can further include thermally connecting the first end of the thermal conduit to a heat producing electronic device. The method can also include thermally connecting the second end of the thermal conduit to a heat dissipating device.

[00051 As used herein, entities that have a "thermal connection", or entities referred to as "thermally connected", refer to two or more entities between which energy in the form of heat, i.e. thermal energy, may be transmitted, transported, conveyed, or otherwise communicated. Typically, a thermal connection includes a physical interface between the entities, however it is to be noted that a thermal connection may be established between two entities via the use of one or more conduits suitable for the transmission of thermal energy linking the entities. In one or more embodiments, the one or more conduits can be a solid or hollow conduit having a high coefficient of thermal conductivity. In one illustrative example, two entities can be thermally operably connected by mere proximity thereby permitting direct conductive heat transfer, or physically remote entities can be thermally connected using one or more conduits adapted to transfer all or a portion of the heat from one entity to another entity.

[0006] A heat transfer system is also provided. The system can include a heat producing electronic device and a heat dissipating device, each disposed at least partially within an electronic device enclosure. A thermal conduit having a first end and a second end can also be at least partially disposed within the electronic device enclosure. A non-heat conductsve material can be disposed at least partially about at least a portion of the thermal conduit. The first end of the thermal conduit can be thermally connected to the heat producing electronic device, and the second end of the thermal conduit can be thermally connected to the heat dissipating device,

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Advantages of one or more disclosed embodiments may become apparent upon reading the following detailed description and upon reference to the drawings in which:

[0008] Fig. 1 depicts an upper perspective view of an exemplary heat transfer apparatus, according to one or more embodiments described herein;

[0009] Fig. 2A depicts a schematic diagram showing an illustrative heat flow in an exemplary heat transfer apparatus, according to one or more embodiments described herein;

[0010] Fig. 2B depicts a schematic diagram showing an illustrative heat flow in another exemplary heat transfer apparatus, according to one or more embodiments described herein;

[0011] Fig. 3 depicts a plan view of an illustrative heat transfer system, according to one or more embodiments described herein.

DETAILED DESCRIPTION

[0012] Fig. 1 depicts an upper perspective view of an exemplary heat transfer apparatus 100, according to one or more embodiments. The exemplary heat transfer apparatus 100 can include a thermal conduit 1 10 having a first end 120 and a second end 130. The thermal conduit 1 10 can be partially or completely disposed within an electronic device enclosure 140. A non-heat conductive material 150 can be at least partially disposed about at least a portion of the thermal conduit 1 10. The thermal conduit 1 10 can be thermally connected to a heat producing device 160 at the first end 120, and to a heat dissipating device 170 at the second end 130. [0013] The thermal conduit 110 can include one or more systems, devices, or combination of systems and devices suitable for conducting, transferring or otherwise transmitting all or a portion of the thermal energy inputted at the first end 120 to the second end 130. The thermal conduit 1 10 can have any physical shape or geometry. The thermal conduit 1 10 can be a solid or hollow member. In one or more embodiments, the thermal conduit 1 10 can be a sealed hollow member having an internal structure, for example a heat pipe or vapor chamber having a wick and phase-change heat transfer fluid disposed therein. In one or more embodiments, the thermal conduit 1 10 can be a material having a high thermal conductivity, for example an aluminum or aluminum alloy conduit having a thermal conductivity of about 250 Watts/meter- Kelvin (W/m-K) or more; or a copper or copper alloy having a thermal conductivity of about 400 W/m-K or more.

[0014] In one or more embodiments, the thermal conduit 1 10 can transfer all or a portion of the thermal energy or heat input at the first end 120 to the second end 130 by conduction, e.g. by maintaining the second end 130 at a temperature less than the temperature of the first end 120. In one or more embodiments, the thermal conduit 110 can transfer all or a portion of the thermal energy or heat input at the first end 120 to the second end 130 by convection, e.g. by transferring at least a portion of the heat input to a fluid within the thermal conduit that flows from the first end 120 to the second end 130 and returns. In one or more embodiments, the thermal conduit can transfer all or a portion of the thermal energy or heat input at the first end 120 to the second end 130 by a combination of conduction and convection.

[0015] The electronic device enclosure 140 can include devices, systems, or any combination of systems and devices suitable for partially or completely housing the thermal conduit 1 10. In one or more embodiments, the electronic device enclosure 140 can include any structure suitable for partially or completely housing an electronic device, for example a portable computer, a laptop computer, a netbook, an ultraportable computer, a cellular device, a personal digital assistant ("PDA"), a handheld gaming system, or the like. The electronic device enclosure 140 can be any metallic or non-metallic material. Suitable metallic materials can include, but are not limited to, aluminum, magnesium, titanium, and the like. Suitable non-metallic materials can include, but are not limited to, polystyrene, acrylonitrile butadiene styrene ("ABS"), carbon fibre, and the like.

[0016] In one or more embodiments, one or more of the thermal conduit 1 10, the heat producing device 180, and the heat dissipating device 170 can be disposed proximate all or a portion of the electronic device enclosure 140. Radiant heat emitted by the thermal conduit 1 10 can cause an increase in the surface temperature of the portion of the electronic device enclosure 140 proximate the thermal conduit 1 10.

[0017] To minimize or eliminate the increase in electronic device enclosure 140 surface temperature proximate the thermal conduit 110, in one or more embodiments, a non-heat conductive materia! 150 can be partially or completely disposed about all or a portion of the thermal conduit 1 10. In one or more embodiments, the non-heat conductive material 150 can include a coating bonded or otherwise partially or completely disposed about all or a portion of the thermal conduit 1 10. In one or more embodiments, the non-heat conductive material 150 can include a sleeve, sock, or similar structure into which all or a portion of the thermal conduit 1 10 can be inserted.

[0018] In one or more embodiments, the non-heat conductive material 150 can include one or more strips disposed helically about all or a portion of the thermal conduit 1 10, as depicted in Fig. 1 . In one or more specific embodiments, the non-heat conductive material 150 can include one or more continuous strips of woven silica, fiberglass, or mineral wool tape, e.g. automotive type "header tape" disposed spirally or helically about all or a portion of the thermal conduit 1 10. In one or more specific embodiments, the non-heat conductive material 150 can include one or more continuous strips of foil-backed woven silica, fiberglass, or mineral wool tape disposed helically about all or a portion of the thermal conduit 1 10. in one or more specific embodiments, the thermal conductivity of the non-heat conductive material 150 disposed about the thermal conduit 1 10 can be about 1 VV/m-K or less; about 0.5 W/m-K or less; about 0.1 W/m-K or less; or about 0.05 W/m-K or less.

[0019] In one or more embodiments, the first end 120 of the thermal conduit 1 10 can be thermally connected to a heat producing device 160. The heat producing device 180 can include, but are not limited to, an electronic circuit, an integrated circuit, a frictional heat producing device, or any other device capable of producing thermal energy as a direct product or by-product of operation. In one or more specific embodiments, the heat producing device 180 can be an integrated circuit disposed within a computing device. Exemplary heat producing integrated circuits found within computing devices can include, but are not limited to, central processing units (CPUs); solid state storage devices such as random access memory ("RAM"); dynamic random access memory ("DRAM"); permanent digital storage media such as memristors; graphical processing units ("GPUs^"); and the like. In one or more embodiments, the first end 120 of the thermal conduit 1 10 can be directly chemically bonded or otherwise attached to the heat producing device 160 via one or more heat transfer mastics or the like. In one or more embodiments, the first end 120 of the thermal conduit 1 10 can be directly or indirectly mechanically bonded or otherwise attached to the heat producing device 160, for example using mechanical tension, or threaded fasteners.

[0020] In one or more embodiments, the second end 130 of the thermal conduit 1 10 can be thermally connected to a heat dissipating device 170. The heat dissipating device 170 can include systems, devices, or any combination of systems and devices suitable for rejecting all or a portion of the thermal energy supplied to the heat dissipating device 170 via the thermal conduit 1 10. In one or more embodiments, the heat dissipating device 170 can include one or more passive heat dissipating devices, for example an air-cooled radiator such as an extended surface heat exchanger. In one or more embodiments, the heat dissipating device 170 can include one or more actively cooled heat dissipating devices, for example an air mover discharging across all or a portion of an air- cooled radiator, or a radiator cooled using a pumped liquid.

[0021] Fig. 2A depicts a schematic diagram showing an illustrative heat flow in an exemplary heat transfer apparatus 200A, according to one or more embodiments. In one or more embodiments, heat produced by the heat generating device 180 can flow 210 to the first end 120 of the thermal conduit 1 10. Once transferred to the thermal conduit 1 10, heat can flow 220 along the thermal conduit to the second end 130. A portion of the heat flow 220 through the thermal conduit 1 10 can be lost as radiant heat 230 emitted from the elevated temperature surface of the thermal conduit 1 10. Upon reaching the second end of the thermal conduit 1 10, heat can flow 240 to the heat dissipating device 170. Within the heat dissipating device 170, all or a portion of the heat transferred or conveyed from the thermal conduit 1 10 to the heat dissipating device 170 can be rejected or otherwise emitted 250 from the heat dissipating device 170.

[0022] In operation, an adiabatic zone 280 can form proximate all or a portion of the exterior surface of the thermal conduit 1 10. The adiabatic zone 280 is a zone having very little or no thermal gradient or temperature difference that exists between the thermal conduit 110 and the fluid or ambient environment surrounding the thermal conduit 1 10. The actual radiant heat 230 emitted by the thermal conduit 1 10 flows from this adiabatic zone 260 to the fluid or ambient environment surrounding the thermal conduit 1 10.

[0023] The surface temperature of the thermal conduit 1 10 can increase as heat is transferred away from the heat producing device 180 to the heat dissipating device 170. A portion of the heat flow 220 through the thermal conduit 1 10 can be emitted from the exterior surface of the thermal conduit 1 10 as radiant heat 230. Where the thermal conduit 1 10 may be disposed proximate heat sensitive components, or where the thermal conduit 110 may be proximate an exterior wall of the electronic device enclosure 140, such radiant heat 230 can cause an unacceptable temperature increase. For example, where the thermal conduit 1 10 is disposed proximate the bottom surface of a laptop or portable computer, the temperature increase of the bottom surface of the computer can make it uncomfortable or impossible to rest the computer on a user's legs.

[0024] Fig. 2B depicts a schematic diagram showing an illustrative heat flow in another exemplary heat transfer apparatus 2Q0B, according to one or more embodiments. The exemplary heat transfer apparatus 200B depicted in Fig. 2B is similar to the exemplary heat transfer apparatus 200A depicted in Fig. 2A with the exception that a non-heat conductive material 150 has been disposed about a portion of the thermal conduit 1 10.

[0025] in operation, in one or more embodiments, the non-heat conductive material 150 can be disposed about the thermal conduit 1 10 in the region formerly occupied by the adiabatic zone 260 (ref. Fig. 2A). Since the transmission of heat through the non-heat conductive material 150 is retarded or eliminated, the surface temperature of the non-heat conductive material 150 can generally be less than the surface temperature of the underlying thermal member 1 10. The lower surface temperature of the non-heat conductive material 150 can result in a lower temperature adiabatic zone 280 forming proximate the non-heat conductive material 150. In turn, the lower temperature adiabatic zone 280 can reduce the overall amount or quantity of radiant heat 270 emitted to the fluid or ambient environment surrounding the thermal member 1 10 by the system 200B.

[0026] Thus, as a consequence of the disposal of the non-heat conductive material 150 about the thermal conduit 110, the radiant heat 270 can be less than the radiant heat 230 emitted from the thermal conduit 1 10 in the absence of the non-heat conductive material 150. In one or more embodiments, the reduced heat loss from the thermal member 110 to the surrounding environment can increase the operating temperature of the heat-dissipating device 170, thereby improving the overall efficiency of the heat-dissipating device 170. Improving the efficiency of the heat-dissipating device 170 can permit the use of physically smaller heat-dissipating devices 170, thereby freeing additional space within the electronic device enclosure 140.

[0027] Additionally, by reducing the quantity and intensity of the radiant heat 270 emitted from the thermal conduit 1 10, the heat transmitted to nearby components or to the electronic device enclosure 140 can be minimized or eliminated. Minimizing the radiant heat 270 emitted by the thermal conduit 1 10 can, for example, minimize or eliminate the temperature rise of the electronic device enclosure 140, thereby improving user comfort when resting the computer on a user's legs.

[00281 Fig. 3 depicts a plan view of an illustrative heat transfer system 300, according to one or more embodiments. In one or more embodiments, the system 300 can include a thermal conduit 1 10 having a first end 120 and a second end 130 disposed at least partially within an electronic device enclosure 140. A non-heat conductive material 150 can be disposed about the exterior surface of at least a portion of the thermal conduit 1 10. The first end 120 of the thermal conduit 1 10 can be thermally connected to a heat producing device 180, for example a CPU as depicted in Fig. 3. The second end 130 of the thermal conduit can be thermally connected to a heat dissipating device 170, for example a passive parallel fin radiator as depicted in Fig. 3. An air mover 310 can be disposed proximate the heat dissipating device 170 such that at least a portion of the discharge airflow 320 passes over, through, or about the heat dissipating device 170. In one or more embodiments, the thermal conduit 1 10, heat producing device 160, heat dissipating device 170, and air mover 310 can be disposed on a substrate 330, for example a computer motherboard disposed within the electronic device enclosure 140.

[0829J In one or more embodiments, the heat producing device 160 can be a board-mount or socket-mount central processing unit disposed in a laptop, or portable computing device. Although the thermal conduit 1 10 is depicted as being thermally connected to only one heat producing device 160, any number of heat producing devices 160 can be similarly thermally connected to the thermal conduit 1 10 using one or more "branches." For example, in one or more embodiments, a GPU and one or more memory modules can also be thermally connected to the thermal conduit 110. Heat generated by the heat producing device 160 can be transmitted via the thermal conduit 1 10 to the heat dissipating device 170 where the airflow 320 provided by the air mover 310 can remove or otherwise dissipate the heat transported by the thermal conduit 1 10.

[0030] In one or more embodiments, the thermal conduit 110 can be a vapor chamber having a wick and a heat transfer fluid disposed therein. Using a vapor chamber, heat from the heat producing device 180 can vaporize a portion of the heat transfer fluid contained in the wick disposed within the thermal conduit 110 proximate the heat producing device 160. The vaporized heat transfer fluid can flow via the thermal conduit 1 10 to a point proximate the heat dissipating device 170. As the vaporized heat transfer fluid is cooled by the heat dissipating device 170, at least a portion of the heat transfer fluid can condense and be absorbed into the wick disposed within the thermal conduit 1 10 proximate the heat dissipating device 170. The condensed heat transfer fluid can flow via capillary action through the wick back to a location proximate the heat producing device 160 where the vaporization/condensation cycle can once again occur.

[0031] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges from any lower limit to any upper limit are contemplated unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values are "about" or "approximately" the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0032] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

CLAIMS: What is claimed Is:

1 . A heat transfer apparatus 100 comprising: a thermal conduit 1 10 having a first end 120 and a second end 130; wherein the thermal conduit is disposed at least partially within an electronic device enclosure 140; and

a non-heat conductive material 150 disposed at least partially about at least a portion of the thermal conduit.

2. The apparatus of claim 1 , wherein the thermal conduit 1 10 comprises a hollow, sealed, metallic member.

3. The apparatus of claim 1 , wherein the non-heat conductive material 150 is selected from the group of materials consisting of: a woven fiberglass material, a woven silica material, a woven mineral wool material, a foil backed woven fiberglass material, a foil backed woven silica material, and a foil backed woven mineral wool material.

4. The apparatus of claim 1 , wherein the non-heat conductive material 150 comprises a coating disposed about the thermal conduit.

5. The apparatus of claim 1 , wherein at least a portion of the first end 120 of the thermal conduit is thermally connected to a heat-producing device 160.

6. The apparatus of claim 1 , wherein at least a portion of the second end 130 of the thermal conduit is thermally connected to a heat-dissipating device 170.

7. A heat transfer method comprising: disposing a non-beat conductive materia! 150 about at least a portion of a thermal conduit 1 10;

wherein the thermal conduit 1 10 comprises a member having a first end 120 and a second end 130;

thermally connecting the first end of the thermal conduit to a heat producing device 160; and

thermally connecting the second end of the thermal conduit to a heat dissipating device 170.

The method of claim 7, wherein the non-heat conductive material 150 is selected from the group of materials consisting of: a woven fiberglass material, a woven silica material, a woven mineral wool material, a foil backed woven fiberglass material, a foil backed woven silica material, and a foil backed woven mineral wool material.

9. The method of claim 7, wherein the non-heat conductive material 150 comprises a coating disposed at least partially about the thermal conduit.

The method of claim 7, wherein the heat dissipating device 170 comprises a passive radiator.

The method of claim 7, further comprising:

disposing a wicking material about at least a portion of the interior of the thermal conduit 1 10; and

disposing a heat transfer fluid within at least a portion of the thermal conduit 1 10.

12. A heat transfer system 200, comprising: a heat producing device 160 disposed at least partially within an electronic device enclosure 140;

a heat dissipating device 170 disposed at least partially within the electronic device enclosure;

a thermal conduit 1 10 having a first end 120 and a second end 130; wherein a non-heat conductive material 150 is disposed at least partially about at least a portion of the thermal conduit; wherein the first end of the thermal conduit is thermally connected to the heat producing electronic device; and

wherein the second end of the thermal conduit is thermally connected to the heat dissipating device.

13. The system of claim 12, wherein the non-heat conductive material 150 comprises a material selected from the group of non-heat conductive materials consisting of: a flexible non-heat conductive material disposed helically about the thermal conduit, a non-heat conductive coating disposed about the thermal conduit, and a non-heat conductive sleeve disposed about the thermal conduit.

14. The system of claims 12 or 13;

wherein the electronic device enclosure 140 comprises an enclosure disposed at least partially about a computing device 220;

wherein the heat producing electronic device 160 comprises an integrated circuit; and

wherein the heat dissipating electronic device 170 comprises an extended-surface radiator.

15. The system of claims 12, 13, or 14 further comprising an air mover 210 having an air discharge wherein at least a portion of the air discharge passes across the heat dissipating device 170.