Capillary evaporator

• US 20030159809A1
• Filed: 02/26/2003
• Published: 08/28/2003
• Est. Priority Date: 02/26/2002
• Status: Active Grant

• Current Assignee: Mikros Manufacturing, LLC
• Original Assignee: Mikros Manufacturing, Inc.
• Inventors: Valenzuela, Javier A.
• Granted Patent: US 6,863,117 B2
• Time in Patent Office: Days
• US Class Current: 165/104.26
• 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: Y10T 29/49353 Heat pipe device making

Abstract

A capillary evaporator (100) for removing heat from a heat source (102), particularly under high heat-flux conditions. The capillary evaporator includes a housing (104) having a plurality of ribs (108) in thermal communication with the heat source when the heat source is present. The ribs define a plurality of vapor channels (110) for receiving vapor (112) caused by the vaporization of working fluid (114) within the evaporator. A capillary wick (106) is located within the housing in spaced relation to the ribs. A bridge (118) interposed between the capillary wick and ribs thermally communicates heat from the ribs to the wick and fluidly communicates the vapor from the wick to the vapor channels. The bridge includes a plurality of fractal layers (FL) each having openings (122) and webs (128) that are scaled in size and number with respect to the immediately adjacent fractal layer and are arranged so that the openings in adjacent layers overlap one another. The fractal layers are arranged so that the fractal layer having the most, and smallest, openings is located immediately adjacent the wick and the fractal layer having the least, and largest, openings is located proximate the ribs. This structure provides the bridge with a superior compromise between the competing criteria of spreading heat evenly from the ribs to the surface of the wick and providing a high permeability for vapor flowing from the wick to the vapor channels.

Claims

1. A capillary evaporator, comprising:

a) at least one first rib defining at least one first channel;

b) a capillary wick confronting, and spaced from, said at least one first rib; and

c) a first bridge located between said at least one first rib and said capillary wick and providing fluid communication between said capillary wick and said at least one first channel and thermal- communication between said capillary wick and said at least one first rib, said first bridge including internal features having sizes that decrease in a direction from said at least one first rib to said capillary wick.

2. A capillary evaporator according to claim 1, wherein said at least one first channel is a vapor-side channel.

3. A capillary evaporator according to claim 1, wherein said at least one first channel is a liquid-side channel.

4. A capillary evaporator according to claim 1, wherein said internal features are a plurality passageways.

5. A capillary evaporator according to claim 4, wherein said first bridge comprises a plurality of layers each having a plurality of openings such that each of said plurality of layers has a different number of said plurality of openings so as to define said plurality of passageways, wherein said different numbers of said plurality of openings increase with increasing distance of said plurality of layers from said at least one rib.

6. A capillary evaporator according to claim 5, wherein said first bridge comprises a plurality of sheets corresponding to said plurality of layers.

7. A capillary evaporator according to claim 6, wherein each of said plurality of sheets is a solid body having corresponding ones of said plurality of openings formed therein.

8. A capillary evaporator according to claim 5, wherein each of said pluralities of openings have the same shapes as one another.

9. A capillary evaporator according to claim 8, wherein each of said pluralities of openings is polygonal.

10. A capillary evaporator according to claim 9, wherein each of said pluralities of openings is rectangular.

11. A capillary evaporator according to claim 8, wherein each of said pluralities of openings is circular.

12. A capillary evaporator according to claim 5, wherein said plurality of openings in each of said plurality of layers has a pitch, said pitches decreasing with increasing distance of the corresponding ones of said plurality of layers from said at least one first rib.

13. A capillary evaporator according to claim 5, wherein each of said plurality of layers has a thickness, said thicknesses decreasing with increasing distance of the corresponding ones of said plurality of layers from said at least one first rib.

14. A capillary evaporator according to claim 1, wherein said capillary wick has a first face confronting said first bridge and a second face spaced from said first face, the capillary evaporator further comprising a second bridge confronting said second face of said capillary wick, said second bridge including internal features having sizes that increase in a direction away from said capillary wick.

15. A capillary evaporator according to claim 14, further comprising at least one second rib defining at least one second channel, each of which confronts said second bridge opposite said capillary wick.

16. A capillary evaporator, comprising:

a) at least one rib defining at least one channel;

b) a capillary wick confronting, and spaced from, said at least one rib; and

c) a bridge having a first region in thermal communication with said at least one rib, a second region spaced from said first region and in thermal communication with said capillary wick, and a plurality of internal passageways each having a cross-sectional area, wherein said plurality of internal passageways become more numerous from said first region to said second region and said cross-sectional areas of said plurality of passageways become smaller from said first region to said second region.

17. A capillary evaporator according to claim 16, wherein said bridge comprises a plurality of layers each having a plurality of openings such that each of said plurality of layers has a different number of said plurality of openings so as to define said plurality of passageways, wherein said different numbers of said plurality of openings increase with increasing distance of said plurality of layers from said at least one rib.

18. A capillary evaporator according to claim 17, wherein said bridge comprises a plurality of sheets corresponding to said plurality of layers.

19. A capillary evaporator according to claim 18, wherein each sheet is a solid body having corresponding ones of said plurality of openings formed therein.

20. A capillary evaporator, comprising:

a) a structure having at least one rib defining at least one channel;

b) a capillary wick spaced from said at least one rib; and

c) a bridge located between, and in thermal communication with, said capillary wick and said at least one rib and providing fluid communication between said capillary wick and said at least one channel, said bridge comprising a plurality of layers each including a number of openings each having an area, wherein said number of openings increases with increasing distance of corresponding ones of said plurality of layers from said at least one rib and said areas of said openings in each of said plurality of layers decrease with increasing distance of corresponding ones of said plurality of layers from said at least one rib.

21. A capillary evaporator according to claim 20, wherein said bridge comprises a plurality of sheets corresponding to said plurality of layers.

22. A capillary evaporator according to claim 21, wherein said plurality of sheets are diffusion bonded to one another.

23. A capillary evaporator according to claim 21, wherein each sheet is a solid body having corresponding ones of said plurality of openings formed therein.

24. A capillary evaporator, comprising:

a) a capillary wick having a first face and a second face spaced from said first face;

b) a first bridge confronting said first face of said capillary wick and having a plurality of first internal passageways each having a first cross-sectional area, wherein said plurality of first internal passageways become less numerous in a direction away from said capillary wick and said first cross-sectional areas of said plurality of first internal passageways become larger in a direction away from said capillary wick; and

c) a second bridge confronting said second face of said capillary wick and having a plurality of second internal passageways each having a second cross-sectional area, wherein said plurality of second internal passageways become less numerous in a direction away from said capillary wick and said second cross-sectional areas of said plurality of second internal passageways become larger in a direction away from said capillary wick.

25. A capillary evaporator according to claim 24, wherein said capillary wick has a length and is substantially flexible over said length.

26. A capillary evaporator according to claim 24, wherein at least one of said first and second bridges comprises a plurality of layers each having a plurality of openings such that each of said plurality of layers has a different number of said plurality of openings so as to define said respective ones of said pluralities of first and second passageways, wherein said different numbers of said plurality of openings decrease with increasing distance of said plurality of layers from said capillary wick.

27. A system, comprising:

a) a capillary evaporator, comprising;

i) at least one rib defining at least one channel;

ii) a capillary wick confronting, and spaced from, said at least one rib; and

iii) a bridge located between said at least one rib and said capillary wick and providing fluid communication between said capillary wick and said at least one channel and thermal communication between said capillary wick and said at least one first rib, said bridge including internal features having sizes that decrease from said at least one rib to said capillary wick; and

b) a heat source in thermal communication with said at least one rib.

28. A system according to claim 27, wherein said heat source comprises a microprocessor.

29. A system according to claim 27, wherein said heat source comprises at least one of a laser and a laser diode array.

30. A method of forming a bridge for a capillary evaporator having a capillary wick and at least one rib, comprising the steps of:

a) providing a plurality of sheets each having openings of different number and different sizes such that the one of said plurality of sheets having the largest of said different sizes of said openings has the least of said different number of said openings and the one of said plurality of sheets having the smallest of said different sizes of said openings has the most of said different number of said openings;

b) locating said plurality of sheets between the capillary wick and the at least one rib such that the one of said plurality of sheets having the smallest ones of said openings is proximate the wick and the one of said plurality of sheets having the largest ones of said openings is proximate said at least one rib.

31. A method according to claim 30 wherein step a includes forming said openings in each of said plurality of sheets.

32. A method according to claim 31, wherein the step of forming said openings includes etching.

33. A method according to claim 31, wherein the step of forming said openings includes machining.

34. A method according to claim 33, wherein said machining includes laser machining.

35. A method according to claim 33, wherein said machining includes electrical discharge machining.

36. A method according to claim 33, wherein said machining includes mechanical machining.

37. A method according to claim 30, further comprising the step of bonding said plurality of sheets to one another.

38. A method according to claim 30, further comprising the step of bonding the bridge to the at least one rib.