System and method of a heat transfer system with an evaporator and a condenser

• US 7,723,845 B2
• Filed: 10/31/2007
• Issued: 05/25/2010
• Est. Priority Date: 09/16/2005
• Status: Expired due to Fees

• Current Assignee: University of Cincinnati
• Original Assignee: University of Cincinnati
• Inventors: Shuja, Ahmed, Medis, Praveen, Parimi, Srinivas, Henderson, H. Thurman, Gerner, Frank M.
• Primary Examiner(s): Pham; Thanh V
• Application Number:
  US11/932,911
• Publication Number:
  US 20080110598A1
• Time in Patent Office: 937 Days
• Field of Search: 257/721, 257/722, 257/E23.097, 257/E31.013, 165/207, 165/302, 165/DIG.218, 623/32, 361/701, 361/703, 361/705, 361/706, 298/900.7
• US Class Current: 257/722
• CPC Class Codes: F28D 15/043 forming loops, e.g. capillary pumped loops
• CPC Class Codes: H01L 23/427 Cooling by change of state, e.g. use of heat pipes by liquefied gas H01L23/445
• 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: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: Y10S 165/218 Condensor adapted to cover opening at top of vapor generator
• CPC Class Codes: Y10T 29/49396 Condenser, evaporator or vaporizer making

Abstract

The present invention is a MEMS-based two-phase LHP (loop heat pipe) and CPL (capillary pumped loop) using semiconductor grade silicon and microlithographic/anisotrophic etching techniques to achieve a planar configuration. The principal working material is silicon (and compatible borosilicate glass where necessary), particularly compatible with the cooling needs for electronic and computer chips and package cooling. The microloop heat pipes (μLHP™) utilize cutting edge microfabrication techniques. The device has no pump or moving parts, and is capable of moving heat at high power densities, using revolutionary coherent porous silicon (CPS) wicks. The CPS wicks minimize packaging thermal mismatch stress and improves strength-to-weight ratio. Also burst-through pressures can be controlled as the diameter of the coherent pores can be controlled on a sub-micron scale. The two phase planar operation provides extremely low specific thermal resistance (20-60 w/cm²). The operation is dependent upon a unique micropatterened CPS wick which contains up to millions per square centimeter of stacked uniform micro-through-capillaries in semiconductor-grade silicon, which serve as the capillary “engine,” as opposed to the stochastic distribution of pores in the typical heat pipe wick. As with all heat pipes, cooling occurs by virtue of the extraction of heat by the latent heat of phase change of the operating fluid into vapor.

Claims

1. A system for transferring heat, the heat transfer system comprising:

an evaporator comprising a semiconductor layer having porous regions formed at predetermined regions;

wherein a first surface of the semiconductor layer encapsulated by a cap structure via contacts at a first portion of non-porous regions of the semiconductor layer, a second surface of the semiconductor layer coupled to a chamber formed with a recessed region adjacent to the second surface of the semiconductor layer; and

wherein the chamber is formed with at least one liquid inlet port and the cap structure is formed with at least one vapor outlet port;

a condenser having at least one vapor inlet port and at least one liquid outlet port;

at first set of channels to couple the at least one vapor outlet port of the evaporator with the at least one vapor inlet port of the condenser;

a second set of channels to couple the at least one liquid outlet port of the condenser with the at least one liquid inlet port of the evaporator; and

wherein the first and second sets of channels form a substantially hermetically sealed chamber between the evaporator and the condenser.

2. The system of claim 1, wherein, the porous regions of the semiconductor layer, comprises substantially of, coherent porous silicon.

3. The system of claim 1, wherein the cap structure is formed with protruding structures that extend inward from an interior surface of the cap structure to contact the first surface of the semiconductor layer at a second portion of the set of non-porous regions of the semiconductor layer.

4. The system of claim 1, wherein liquid is disposable in the recessed region of the chamber to be substantially in contact with at least a portion of the porous regions at the second surface of the semiconductor layer;

wherein the liquid is to be supplied via the at least one liquid inlet port.

5. The system of claim 1, wherein the chamber comprises substantially of, one or more of, borosilite glass, silicon, ceramics, and silicon dioxide.

6. The system of claim 1, wherein an exterior surface of the cap structure is suited to be thermally coupled to a heat source.

7. The system of claim 1, wherein the first layer is coupled to the cap structure via wafer bonding.

8. The system of claim 1, where in the chamber is coupled to the second surface of the first layer via wafer bonding.

9. The system of claim 1, wherein the cap structure comprises substantially of, thermally conductive material.

10. The system of claim 9, wherein the cap structure comprises substantially of one or more of, silicon and CMOS-grade silicon.

11. The system of claim 1, wherein the condenser is one or more of, formed with fin-like structures and thermally coupled to fin-like structures.

12. The system of claim 11, wherein the condenser comprises substantially of, one or more of, copper-based substances, aluminum-based substances, and silver-based substances.

13. The system of claim 1, further comprising a fluid-guiding structure formed around at least a portion of the condenser, the fluid-guiding structure having a coolant inlet and a coolant outlet.