HIGH PERFORMANCE WICK

• US 20110146956A1
• Filed: 05/05/2009
• Published: 06/23/2011
• Est. Priority Date: 05/05/2008
• Status: Active Grant

• Current Assignee: Cornell University
• Original Assignee: Cornell University
• Inventors: Stroock, Abraham D., Wheeler, Tobias
• Granted Patent: US 9,702,636 B2
• Time in Patent Office: Days
• US Class Current: 165/104.26
• CPC Class Codes: F28D 15/046 characterised by the material or the construction of the capillary structure
• CPC Class Codes: Y10T 428/24322 Composite web or sheet

Abstract

A wicking apparatus includes a composite condenser membrane comprising a substrate layer, a vapor inlet end, a liquid discharge end, a plurality of cavities disposed in the substrate layer fluidly coupling the vapor inlet end to the liquid discharge end, and a nanoporous filler material disposed within the plurality of cavities. The nanoporous filler material has a first plurality of open pores with a maximum diameter in the range of 0.2 to 200 nanometers. The first end of the liquid conduit is fluidly coupled to the liquid discharge end of the composite condenser membrane. The wicking apparatus further includes a wick composite evaporator membrane comprising a substrate layer, a liquid inlet end, a vapor discharge end, a plurality of cavities disposed in the substrate layer fluidly coupling the liquid inlet end to the second end of the liquid conduit, and a nanoporous filler material disposed within the plurality of cavities.

Claims

1. A wicking apparatus comprising:

a composite condenser membrane comprising a substrate layer, a vapor inlet end, a liquid discharge end, a plurality of cavities disposed in the substrate layer fluidly coupling the vapor inlet end to the liquid discharge end, and a nanoporous filler material disposed within the plurality of cavities, the nanoporous filler material having a first plurality of open pores, the first plurality of open pores having a maximum diameter in the range of 0.2 to 200 nanometers;

a liquid conduit having a first end and a second end, the first end of the liquid conduit being fluidly coupled to the liquid discharge end of the composite condenser membrane; and

a composite evaporator membrane comprising a substrate layer, a liquid inlet end, a vapor discharge end, a plurality of cavities disposed in the substrate layer fluidly coupling the liquid inlet end to the second end of the liquid conduit, and a nanoporous filler material disposed within the plurality of cavities, the nanoporous filler material having a second plurality of open pores, the second plurality of open pores having a maximum diameter in the range of 0.2 to 200 nanometers.

2. The wicking apparatus of claim 1 wherein the first plurality of open pores in the composite condenser membrane and the second plurality of open pores in the composite evaporator membrane are sized to provide a pre-determined pressure differential across the respective composite membrane.

3. The wicking apparatus of claim 1 wherein at least one of the substrate layer of the condenser membrane and the substrate layer of the evaporator membrane is porous.

4. The wicking apparatus of claim 3 wherein the respective substrate layer comprises silicon.

5. The wicking apparatus of claim 3 wherein the respective plurality of cavities are interstitial voids formed in the lattice structure of the substrate layer, the interstitial voids having a mean diameter in the range of 20 to 200 nanometers.

6. The wicking apparatus of claim 1 wherein at least one of the first plurality of open pores and the second plurality of open pores have a maximum diameter in the range of 1 to 10 nanometers.

7. The wicking apparatus of claim 1 wherein the nanoporous filler material disposed within the cavities of at least the composite evaporator membrane comprises a molecular gel.

8. The wicking apparatus of claim 7 wherein the molecular gel is a sol-gel.

9. The wicking apparatus of claim 7 wherein the molecular gel is a hydrogel.

10. The wicking apparatus of claim 1 further comprising a molecular membrane disposed adjacent the composite evaporator membrane or the composite condenser membrane.

11. The wicking apparatus of claim 10 wherein the molecular membrane is a hydrogel membrane.

12. The wicking apparatus of claim 1 wherein the liquid conduit is greater than 1 meter in length.

13. The wicking apparatus of claim 1 wherein the liquid conduit comprises a channel 100 to 500 micrometers deep.

14. The wicking apparatus of claim 1 wherein the liquid conduit further comprises a vapor block and a porous body member disposed adjacent to the vapor block, the vapor block configured to redirect a flow of working fluid through the porous body member.

15. The wicking apparatus of claim 14 wherein the porous body member has pores in the range of 1 to 100 nanometers.

16. The wicking apparatus of claim 14 wherein a plurality of vapor blocks are arranged to create a plurality of segments within the liquid conduit, the segments fluidly coupled in an axial direction and a lateral direction by the porous body member.

17. A composite membrane for use in a capillary wick, comprising:

a substrate layer having a liquid end, a vapor end, and a plurality of cavities fluidly coupling the liquid end to the vapor end; and

a filler material disposed within the plurality of cavities, the filler material having a plurality of open pores, the pores having a maximum diameter in the range of 0.2 to 100 nanometers.

18. The composite membrane of claim 17 wherein the maximum diameter of the pores is in the range of 1 to 10 nanometers.

19. The composite membrane of claim 17 wherein the filler material is a molecular gel.

20. The composite membrane of claim 19 wherein the molecular gel is organic.

21. The composite membrane of claim 20 wherein the organic molecular gel is a hydrogel.

22. The composite membrane of claim 19 wherein the filler material is inorganic.

23. The composite membrane of claim 22 wherein the inorganic filler material is a sol-gel.

24. The composite membrane of claim 23 wherein the sol-gel is a silica sol-gel.

25. The composite membrane of claim 17 further comprising a molecular gel membrane disposed adjacent the filler material.

26. The composite membrane of claim 25 wherein the molecular gel membrane is a hydrogel membrane.

27. The composite membrane of claim 25 wherein the molecular gel membrane is disposed on the vapor end of the wick.

28. The composite membrane of claim 17 wherein the plurality of cavities comprise open pores having a diameter in the range of 20 nanometers to 10 micrometers.

29. The composite membrane of claim 17 wherein the substrate layer is porous.

30. The composite membrane of claim 29 wherein the substrate layer comprises silicon.

31. The composite membrane of claim 30 wherein the silicon is single crystalline porous silicon.

32. The composite membrane of claim 29 wherein the plurality of cavities comprise interstitial voids formed in the lattice structure of the substrate layer, the interstitial voids having a mean diameter in the range of 20 to 200 nanometers.

33. In a heat pipe comprising a condenser, a composite evaporator membrane, a liquid conduit fluidly coupling the condenser to the composite evaporator membrane, and a vapor conduit fluidly coupling the composite evaporator membrane to the condenser, a method for operating the heat pipe comprising the steps of:

providing a heat source proximate to the composite evaporator membrane;

providing a heat sink proximate to the condenser;

providing a first plurality of open pores in the composite evaporator membrane, the pores having a maximum diameter in the range of 0.2 to 100 nanometers;

providing a working fluid within the liquid conduit; and

maintaining a pressure of the working fluid in the liquid conduit at less than −

0.01 megapascals.

34. The method of claim 33 further including the step of operating the heat pipe in an under-charged regime.

35. The method of claim 33 wherein the pressure of the working fluid in the liquid conduit is maintained at less than −

1.0 megapascals.

36. The method of claim 35 wherein the pressure of the working fluid in the liquid conduit is maintained at less than −

5.0 megapascals.

37. The method of claim 33 wherein the composite evaporator membrane comprises a substrate layer having a plurality of cavities, and a filler material disposed within the plurality of cavities, the filler material having the first plurality of open pores.

38. The method of claim 37 wherein the filler material is a molecular gel.

39. The method of claim 37 wherein the molecular gel is a sol-gel.

40. The method of claim 33 wherein a maximum pore diameter of the first plurality of open pores is in the range of 1 to 10 nanometers.

41. The method of claim 33 wherein the condenser is a composite condenser membrane, and the method further includes the step of providing a second plurality of open pores in the composite condenser membrane, the second plurality of open pores having a maximum diameter in the range of 0.2 to 100 nanometers.

42. The method of claim 41 wherein the composite condenser membrane comprises a substrate layer having a plurality of cavities, and a filler material disposed within the plurality of cavities, the filler material having the second plurality of open pores.

43. The method of claim 42 wherein the filler material is a molecular gel.

44. The method of claim 43 wherein the molecular gel is a sol-gel.