Heat exchange enhancement

• US 7,826,214 B2
• Filed: 03/28/2008
• Issued: 11/02/2010
• Est. Priority Date: 03/31/2006
• Status: Expired due to Fees

• Current Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Original Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Inventors: Shuy, Geoffrey Wen-Tai
• Primary Examiner(s): Gandhi; Jayprakash N
• Assistant Examiner(s): Thomas; Bradley H
• Application Number:
  US12/057,722
• Publication Number:
  US 20080173432A1
• Time in Patent Office: 949 Days
• Field of Search: 361/705, 174/15.2, 174/16.1
• US Class Current: 361/679.47
• CPC Class Codes: F21K 9/20 Light sources comprising attachment means
• CPC Class Codes: F21S 43/14 Light emitting diodes [LED]
• CPC Class Codes: F21S 45/48 with means for conducting heat from the inside to the outside of the lighting devices, e.g. with fins on the outer surface of the lighting device
• CPC Class Codes: F21V 29/51 using condensation or evaporation of a fluid, e.g. heat pipes
• CPC Class Codes: F21V 29/713 in direct thermal and mechanical contact of each other to form a single system
• CPC Class Codes: F21V 29/83 the elements having apertures, ducts or channels, e.g. heat radiation holes
• CPC Class Codes: F21V 29/86 Ceramics or glass
• CPC Class Codes: F21V 29/89 Metals
• CPC Class Codes: F21V 31/005 Sealing arrangements therefor
• CPC Class Codes: F21W 2131/103 of streets or roads
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F28D 1/0233 with air flow channels
• CPC Class Codes: F28D 15/0233 the conduits having a particular shape, e.g. non-circular cross-section, annular F28D15/0241, F28D15/0266 take precedence
• CPC Class Codes: F28D 15/0275 Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
• CPC Class Codes: F28F 13/185 Heat-exchange surfaces provided with microstructures or with porous coatings
• CPC Class Codes: F28F 21/04 of ceramic; of concrete; of natural stone
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 7/20009 using a gaseous coolant in electronic enclosures in cabinets of standardized dimensions H05K7/20536; in server cabinets H05K7/20709; in vehicle electronic casings H05K7/20845; in power control electronics H05K7/2089; in displays H05K7/20954
• CPC Class Codes: H05K 7/20154 : Heat dissipaters coupled to components
• CPC Class Codes: Y10T 29/4935 : Heat exchanger or boiler making

Abstract

A heat exchange structure includes elongated air ducts. Each air duct has a first opening and a second opening at two ends of the air duct to allow air to enter and exit the air duct, respectively. The heat exchange structure includes an exterior heat exchange surface and interior heat exchange surfaces, in which the exterior heat exchange surface is configured to receive thermal energy from heat generators that are mounted on the exterior heat exchange surface, and the exterior heat exchange surface dissipates a portion of the thermal energy received from the heat generators and transfers another portion of the thermal energy to the interior heat exchange surfaces. The interior heat exchange surfaces are in the elongated air ducts and configured to exchange thermal energy with air flowing in the air ducts, enhancing air flow in the air ducts by buoyancy of heated air.

Claims

1. A method comprising:

receiving thermal energy from heat generators at an exterior heat exchange surface of a heat exchange structure, the heat exchange structure comprising a plurality of elongated air ducts, the heat generators positioned along an elongated direction of the air ducts;

transferring a portion of the thermal energy from the exterior heat exchange surface to interior heat exchange surfaces of the heat exchange structure, the interior heat exchange surfaces being in the air ducts; and

dissipating heat from the interior heat exchange surfaces to air flowing in the air ducts to cause the heated air to rise due to buoyancy of the heated air;

wherein dissipating heat from the interior heat exchange surfaces to air flowing in the air ducts further comprises;

transferring thermal energy from the interior heat exchange surfaces to an air-impermeable first surface of a thin layer of ceramic material formed on the interior heat exchange surfaces of the heat exchange structure;

transferring thermal energy through the thin layer of ceramic material from the air-impermeable first surface of the thin layer of ceramic material to a porous second surface of the thin layer of ceramic material;

wherein the porous second surface is exposed to the air flowing in the air ducts;

heating air molecules trapped in pores of the porous second surface of the thin layer of ceramic material; and

transferring thermal energy from the thin layer of ceramic material to the air flowing in the air ducts by moving the air molecules from the pores of the porous second surface of the thin layer of ceramic material to the air flowing in the air ducts.

2. The method of claim 1, wherein transferring thermal energy from the heat generators to the interior heat exchange surfaces comprises direct transfer of heat that avoids thermal transfer through a printed-circuit board (PCB).

3. The method of claim 1, further comprising injecting compressed air into an opening of the air duct.

4. The method of claim 1 in which the heat generators comprise electronic devices.

5. A method comprising:

transferring, through a heat pipe, thermal energy from a heat generator to a heat exchange structure that comprises a plurality of elongated air ducts, a portion of the heat pipe contacting the heat exchange structure being aligned along an elongated direction of the air ducts; and

transferring thermal energy from the heat exchange structure to ambient air flowing in the plurality of air ducts;

wherein transferring thermal energy from the heat exchange structure to ambient air flowing in the plurality of air ducts further comprises;

transferring thermal energy from the heat pipe to an air-impermeable first surface of a thin layer of ceramic material formed on the heat exchange structure;

transferring thermal energy through the thin layer of ceramic material from the air-impermeable first surface of the thin layer of ceramic material to a porous second surface of the thin layer of ceramic material;

wherein the porous second surface is exposed to the ambient air flowing in the plurality of air ducts and the air-impermeable first surface of the thin layer of ceramic material is not exposed to the ambient air flowing in the plurality of air ducts;

heating air molecules trapped in pores of the porous second surface of the thin layer of ceramic material; and

transferring thermal energy from the thin layer of ceramic material to the ambient air flowing in the plurality of air ducts by moving the air molecules from the pores of the porous second surface of the thin layer of ceramic material to the ambient air flowing in the plurality of air ducts.

6. The method of claim 5, further comprising transferring thermal energy from heated vapor or liquid in the heat pipe to the ambient air in the air ducts through a wall having a thickness less than 5 mm.

7. A method comprising:

fabricating a heat exchange structure and a housing of a heat pipe using one piece of metal, the heat exchange structure comprising a plurality of air ducts and heat exchange surfaces in the air ducts,

the heat exchange surfaces configured to exchange heat with air flowing in the air ducts to enhance air flow in the air ducts due to buoyancy of heated air;

coating the heat exchange surfaces in the air ducts with a thin layer of ceramic material;

wherein coating the heat exchange surfaces further comprises initially coating the heat exchange surfaces with a first sub-layer and finally coating the interior heat exchange surfaces with a second sub-layer;

wherein the thin layer of ceramic material is configured to be air impermeable at a first surface of the first sub-layer which attaches to the heat exchange surfaces, and porous at a second surface of the second sub-layer, the second surface being opposed to the first surface and exposed to the air flowing in the air ducts.

8. The method of claim 7, further comprising the thin layer of ceramic material having a thickness less than 100 μ

m.