Phase-change cooling of subterranean power lines

• US 8,872,022 B2
• Filed: 07/18/2012
• Issued: 10/28/2014
• Est. Priority Date: 07/18/2012
• Status: Expired due to Fees

• Current Assignee: Elwha LLC (Intellectual Ventures LLC)
• Original Assignee: Elwha LLC (Intellectual Ventures LLC)
• Inventors: Hyde, Roderick A., Kare, Jordin T., Myhrvold, Nathan P., Tuckerman, David B., Wood, Lowell L. Jr.
• Primary Examiner(s): Estrada, Angel R
• Application Number:
  US13/552,532
• Publication Number:
  US 20140022708A1
• Time in Patent Office: 832 Days
• Field of Search: 174/17.R, 174/17.VA, 174/68.1, 174/68.3, 174/70.C, 174/96, 174/15.5, 174/15.6, 174/16.1, 174/15.1, 174/15.2, 361/677, 361/600, 361/601, 361/678, 361/679.01, 361/688, 361/689, 361/699, 361/701, 361/676, 165/104.11, 165/104.22, 165/104.23, 165/104.28, 165/104.33, 165/104.25, 165/104.31, 165/104.19, 405/154.1, 405/158, 405/159
• US Class Current: 174/15.1
• CPC Class Codes: F24T 10/40 operated without external energy sources, e.g. using thermosiphonic circulation or heat pipes
• CPC Class Codes: F28D 15/02 in which the medium condenses and evaporates, e.g. heat pipes heat pipes used in solar heat collectors F24S10/95; in radiators F28D1/0226; in nuclear reactors G21C15/257
• CPC Class Codes: F28D 2021/0028 for cooling heat generating elements, e.g. for cooling electronic components or electric devices
• CPC Class Codes: H02G 9/02 laid directly in or on the ground, river-bed or sea-bottom; Coverings therefor, e.g. tile
• CPC Class Codes: Y02E 10/10 Geothermal energy

Abstract

A cooling system for a subterranean power line may include a cooling tube configured to house a fluid. Heat generated by the subterranean power line may be radiated and/or conducted to the cooling tube and absorbed by the fluid within the cooling tube. As the fluid heats up, it may change phase from a liquid to a gas. The hot gas may rise to a heat-exchanging condenser configured to dissipate the heat and condense the fluid back into a liquid. The cool, condensed liquid my return from the heat-exchanging condenser to the cooling tube. Risers, gas transport tubes, pressure regulation systems, fluid storage tanks, and other components described herein may increase the efficiency of the cooling system and/or otherwise improve the viability of the cooling system for subterranean power lines.

Claims

1. An underground power transmission system, comprising:

a power line configured for subterranean installation along a first path;

a cooling tube fluidly independent from the power line, the cooling tube configured for subterranean installation along the first path and adjacent to the power line, the cooling tube configured to house a fluid adapted to absorb thermal energy generated by a current flow through the power line; and

a heat-exchanging condenser fluidly connected to the cooling tube, the heat-exchanging condenser configured to;

receive the fluid in a heated, gaseous phase;

dissipate thermal energy stored in the fluid in the gaseous phase; and

return the fluid in a cooled, liquid phase.

2. The system of claim 1, wherein the fluid comprises water.

3. The system of claim 1, wherein the fluid comprises an alcohol.

4. The system of claim 1, further comprising:

a second cooling tube configured for subterranean installation along the first path and adjacent to the power line, the second cooling tube configured to house a second fluid adapted to absorb thermal energy from one of a current flow through the power line and the heat-exchanging condenser;

a second heat-exchanging condenser fluidly connected to the second cooling tube, the second heat-exchanging condenser configured to;

receive the second fluid in a heated, gaseous phase,

dissipate thermal energy stored in the second fluid in the gaseous phase, and

return the second fluid in a cooled, liquid phase.

5. The system of claim 1, wherein the cooling tube comprises a polyvinyl chloride (PVC).

6. The system of claim 1, wherein the fluid is configured to be sealed within the cooling tube and fluidly connected components.

7. The system of claim 6, wherein the fluid within the cooling tube is configured to be depressurized to a pressure below an ambient pressure outside of the cooling tube.

8. The system of claim 1, further comprising a riser fluidly connecting the heat-exchanging condenser to the cooling tube,

wherein a first end of the riser is configured to be installed at a lower elevation than a second end of the riser, and

wherein the first end of the riser is fluidly connected to the cooling tube and the second end of the riser is fluidly connected to the heat-exchanging condenser.

9. The system of claim 8, wherein the riser is configured to be installed extending towards the surface of ground covering the subterranean power line, such that the heat-exchanging condenser is at least partially exposed to the atmosphere.

10. The system of claim 1, further comprising:

a gas transport tube configured to be installed at a higher elevation than the cooling tube; and

at least one riser configured to fluidly connect the cooling tube to the gas transport tube, and

wherein the heat-exchanging condenser is configured to be fluidly connected to the gas transport tube, such that the heat-exchanging condenser is fluidly connected to the cooling tube through the gas transport tube and the at least one riser.

11. The system of claim 10, wherein the at least one riser comprises a plurality of risers.

12. The system of claim 11, wherein each of the plurality of risers is configured to extend from a local elevational maximum in an unevenly buried cooling tube.

13. The system of claim 10, further comprising a condenser riser configured to fluidly connect the heat-exchanging condenser to the gas transport tube,

wherein a first end of the condenser riser is configured to be installed at a lower elevation than a second end of the condenser riser, and

wherein the first end of the condenser riser is configured to be fluidly connected to the gas transport tube and the second end of the condenser riser is configured to be fluidly connected to the heat-exchanging condenser.

14. A method for delivering power via an underground power transmission system, comprising:

installing a power line configured for subterranean installation underground along a first path;

installing a cooling tube fluidly independent from the power line, the cooling tube configured for subterranean installation along the first path and adjacent to the power line;

a fluid within the cooling tube absorbing thermal energy generated by a current flow through the power line; and

a heat-exchanging condenser fluidly connected to the cooling tube;

receiving the fluid in a heated, gaseous phase;

dissipating thermal energy stored in the fluid in the gaseous phase; and

returning the fluid in a cooled, liquid phase.

15. The method of claim 14, wherein the fluid is selected based on at least one thermodynamic condition.

16. The method of claim 15, wherein the thermodynamic condition comprises an enthalpy of vaporization of the fluid.

17. The method of claim 14, wherein the power line and the cooling tube are installed in contact with one another.

18. The method of claim 14, further comprising sealing the fluid within the cooling tube and fluidly connected components.

19. The method of claim 18, further comprising dynamically adjusting the pressure of the fluid within the cooling tube.

20. The method of claim 19, wherein dynamically adjusting the pressure of the fluid within the cooling tube comprises removing a gas from the cooling tube.

21. The method of claim 14, wherein the fluid in a liquid phase is transported within the cooling tube via surface tension forces.

22. The method of claim 21, wherein the fluid in the liquid phase is transported within the cooling tube via wicking tension forces.

23. An underground power transmission system, comprising:

a power line configured for subterranean installation along a first path;

a cooling tube fluidly independent from the power line, the cooling tube configured for subterranean installation along the first path and adjacent to the power line;

a fluid within the cooling tube, the fluid configured to absorb thermal energy generated by a current flow through the power line;

a gas transport tube configured to be installed at a higher elevation than the cooling tube;

at least one riser configured to fluidly connect the cooling tube to the gas transport tube; and

a heat-exchanging condenser fluidly connected to the cooling tube via the gas transport tube and the at least one riser, the heat-exchanging condenser configured to;

receive the fluid in a heated, gaseous phase;

dissipate thermal energy stored in the fluid in the gaseous phase; and

return the fluid in a cooled, liquid phase.

24. The system of claim 23, further comprising a storage tank configured to store a reserve of the fluid and selectively provide the reserved fluid to the cooling tube.

25. The system of claim 23, wherein one of the cooling tube, the gas transport tube, and the at least one riser comprises a metal.

26. The system of claim 23, wherein the fluid is configured to be sealed within the cooling tube and fluidly connected components.

27. The system of claim 26, wherein the pressure within the cooling tubes is configured to be adjusted based on a temperature of a ground material surrounding the cooling tube.

28. The system of claim 26, wherein the pressure within the cooling tubes is configured to be adjusted based on an ambient temperature near the heat-exchanging condenser.

29. The system of claim 23, further comprising a condenser riser fluidly connecting the heat-exchanging condenser to the gas transport tube,

wherein a first end of the condenser riser is configured to be installed at a lower elevation than a second end of the condenser riser, and

wherein the first end of the condenser riser is configured to be fluidly connected to the gas transport tube and the second end of the condenser riser is configured to be fluidly connected to the heat-exchanging condenser.

30. The system of claim 29, wherein the fluid in a liquid phase is configured to be returned from the heat-exchanging condenser to the cooling tube via a return tube.

31. The system of claim 23, wherein the fluid comprises at least one vaporizable liquid.

32. A method of cooling a subterranean power line comprising:

a subterranean power line generating thermal energy by a current flow through the power line, the power line extending along a first path;

a cooling tube receiving at least some of the thermal energy, the cooling tube fluidly independent from the power line and extending along the first path adjacent to the power line;

a fluid within the cooling tube absorbing at least some of the thermal energy received by the cooling tube; and

a heat-exchanging condenser fluidly connected to the cooling tube;

receiving the fluid in a heated, gaseous phase;

dissipating thermal energy stored in the fluid in the gaseous phase; and

returning the fluid in a cooled, liquid phase.

33. The method of claim 32, wherein there exists a gap between the power line and the cooling tube.

34. The method of claim 32, wherein the cooling tube and fluidly connected components are fluidly sealed.

35. The method of claim 34, wherein the pressure within the cooling tube is configured to be adjusted based on a current flow of the power line.

36. The method of claim 34, wherein the pressure within the cooling tube is configured to be adjusted based on a power dissipation within the power line.

37. The method of claim 32, further comprising determining an external condition associated with the underground power transmission system using a sensor system.

38. The method of claim 37, further comprising transmitting information associated with the external condition to a data receiving location.

39. The method of claim 32, wherein the fluid comprises at least one non-condensable gas and at least one vaporizable liquid.

40. The method of claim 32, wherein the fluid in the cooled, liquid phase returns from the heat-exchanging condenser to the cooling tube via capillary grooves.

41. The method of claim 32, wherein the fluid in a liquid phase is transported within the cooling tube via surface tension forces.

42. The method of claim 41, wherein the fluid in the liquid phase is transported within the cooling tube via wicking tension forces.