AXIAL FLOW HEAT EXCHANGER DEVICES AND METHODS FOR HEAT TRANSFER USING AXIAL FLOW DEVICES

• US 20120180992A1
• Filed: 03/01/2012
• Published: 07/19/2012
• Est. Priority Date: 08/13/2010
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Koplow, Jeffrey P.
• Granted Patent: US 9,261,100 B2
• Time in Patent Office: Days
• US Class Current: 165/104.21
• CPC Class Codes: F04D 25/0606 the electric motor being specially adapted for integration in the pump
• CPC Class Codes: F04D 25/0613 the electric motor being of the inside-out type, i.e. the rotor is arranged radially outside a central stator
• CPC Class Codes: F04D 25/066 Linear Motors
• CPC Class Codes: F04D 29/582 specially adapted for elastic fluid pumps
• CPC Class Codes: F04D 29/5853 heat insulation or conduction
• CPC Class Codes: F28D 15/0208 using moving tubes
• 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 15/025 having non-capillary condensate return means
• CPC Class Codes: F28D 7/0016 the conduits for one medium or the conduits for both media being bent F28D7/0033 takes precedence
• CPC Class Codes: F28F 13/02 by influencing fluid boundary boundary-layer control in general F15D
• CPC Class Codes: F28F 13/12 by creating turbulence, e.g. by stirring, by increasing the force of circulation F28F13/08 takes precedence
• CPC Class Codes: F28F 13/125 by stirring
• CPC Class Codes: F28F 2215/06 Hollow fins; fins with internal circuits
• CPC Class Codes: F28F 2250/08 Fluid driving means, e.g. pumps, fans
• CPC Class Codes: F28F 3/02 Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations F28F3/08 takes precedence
• CPC Class Codes: H01L 23/467 by flowing gases, e.g. air H01L23/473 takes precedence
• 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 7/20163 the components being isolated from air flow, e.g. hollow heat sinks, wind tunnels or funnels

Abstract

Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.

Claims

1. A heat exchanger having a length and a center axis substantially parallel to the length, the heat exchanger comprising:

a heat conducting structure having a first surface disposed radially about the center axis and spanning the length;

a heat transfer structure rotatably coupled to the heat conducting structure to form a gas-filled gap region between the first surface of the heat conducting structure and a second surface of the heat transfer structure and configured to transfer heat across the gas-filled gap region, wherein the heat transfer structure is further configured to rotate about the center axis and to generate flow of a heat transfer medium in a substantially axial direction.

2. The heat exchanger of claim 1 wherein the heat conducting structure comprises at least one of a thermally conductive material, a heat pipe, or a vapor chamber.

3. The heat exchanger of claim 1 wherein the heat transfer structure is configured to function as a heat pipe.

4. The heat exchanger of claim 1 wherein at least a portion of the heat transfer structure is disposed inside the heat conducting structure, and wherein the first surface of the heat conducting structure is maintained at a temperature higher than a temperature of a heat transfer medium flowing through the a heat transfer structure.

5. The heat exchanger of claim 1 wherein at least a portion of the heat conducting structure is disposed inside the heat transfer structure, and wherein the first surface of the heat conducting structure is maintained at a temperature lower than a temperature of a heat transfer medium flowing through the a heat transfer structure.

6. The heat exchanger of claim 1 wherein the gap region comprises a gas maintained at a pressure selected to counteract forces applied to the second surface during rotation of the heat transfer structure.

7. The heat exchanger of claim 1 further comprising a motor coupled to the heat transfer structure and configured to rotate the heat transfer structure relative to the heat conducting structure about a common longitudinal axis of the heat conducting structure and the heat transfer structure.

8. The heat exchanger of claim 1 wherein the heat transfer structure comprises a cylinder having a first wall and a second wall, the first wall being substantially parallel to the second wall and defining a first cylindrical region therebetween, the heat transfer structure further comprising a plurality of hollow fins disposed inside the cylinder, the fins having a plurality of inner regions, wherein the fins are attached to the second wall of the cylinder such that at least one of the inner regions of the fins is interconnected with the first cylindrical region of the heat transfer structure.

9. The heat exchanger of claim 8 wherein the first wall and the second wall are connected by a cap, wherein the cap comprises at least one of a bellows, a flexure, or a corrugated wall.

10. The heat exchanger of claim 1 wherein the heat conducting structure comprises a first cylinder, wherein the heat transfer structure comprises a second cylinder having a plurality of structures adapted for the generation of axial flow, and wherein the second cylinder is disposed coaxially relative to the first cylinder.

11. The heat exchanger of claim 10, wherein the plurality of structures adapted for the generation of axial flow comprise at least one of fins, vanes, blades, or combinations thereof.

12. A method of transferring heat between a stationary structure and a finned structure operable to rotate relative to the stationary structure, the method comprising:

rotating the finned structure relative to the stationary structure;

flowing a heat transfer medium through the fumed structure and substantially along a longitudinal axis of the finned structure, the finned structure being in thermal contact with the stationary structure which is configured to function as at least one of a heat source or a heat sink; and

transferring heat across a gas-filled gap defined between the finned structure and the stationary structure in a generally inward radial direction.

13. The method of claim 12, wherein said rotating includes providing electrical power to a motor coupled to the finned structure.

14. The method of claim 12, wherein the finned structure comprises a cylindrical assembly having a plurality of fins adapted for the generation of axial flow, and wherein said rotating comprises rotating the cylindrical assembly to cause the heat transfer medium to flow substantially axially through the finned structure.

15. The method of claim 12, wherein said rotating is, at least in part, generated by said flowing the heat transfer medium through the finned structure.

16. The method of claim 12, wherein said flowing a heat transfer medium includes maintaining the heat transfer medium at a temperature higher than a temperature of a surface of the stationary structure.

17. The method of claim 16, wherein said maintaining includes at least one of heating the heat transfer medium or cooling the surface of the stationary structure.

18. The method of claim 12, wherein said flowing a heat transfer medium includes maintaining the heat transfer medium at a temperature lower than a temperature of a surface of the stationary structure.

19. The method of claim 18, wherein said maintaining includes at least one of cooling the heat transfer medium or heating the surface of the stationary structure.

20. The method of claim 12, wherein the finned array is configured to function as a heat pipe, and wherein said flowing a heat transfer medium includes maintaining the heat transfer medium at a temperature low enough to cause a working fluid inside the heat pipe to condense.

21. The method of claim 12, wherein the finned array is configured to function as a heat pipe, and wherein said flowing a heat transfer medium includes maintaining the heat transfer medium at a temperature high enough to cause a working fluid inside the heat pipe to evaporate.

22. The method of claim 12, wherein the finned structure a cylindrical heat pipe, the heat pipe having a pair of concentric cylindrical walls defining a hollow cylindrical region therebetween, the cylindrical heat pipe further having a plurality of hollow fins arranged radially about a centerline of the cylindrical heat pipe and disposed between the pair of cylindrical wall and the centerline, wherein the plurality of hollow fins are interconnected with the hollow cylindrical region of the pair of concentric cylindrical walls to define a heat pipe cavity, and wherein the heat pipe cavity is maintained at partial vacuum, and wherein said rotating comprises rotating the cylindrical heat pipe about a common centerline of the finned structure and the stationary structure.

23. The method of claim 12, wherein said transferring heat across a gas-filled gap comprises transferring heat across a region having a width selected to provide low thermal resistance.

24. The method of claim 12, wherein the stationary structure is configured to be in thermal contact with a thermal load, and wherein said transferring heat across the gas-filled gap comprises transferring heat from the thermal load to the heat transfer medium.

25. The method of claim 12, and wherein said transferring heat across a gas-filled gap region comprises heating a surface of the heat transfer structure to cause a working fluid interior to a cavity of the heat transfer structure to boil.

26. The method of claim 12, wherein said rotating the finned structure includes applying a centrifugal force on a working fluid contained inside cavities of the finned structure to cause a condensing portion of the working fluid to move within the cavities in an outwardly radial direction.

27. The method of claim 12, wherein said rotating the finned structure includes applying a centrifugal force on a working fluid contained inside cavities of the finned structure to cause a liquid portion of the working fluid to remain disposed about a perimeter of the finned array within the cavities of the finned structure.

28. A rotary heat transfer device comprising:

a first cylinder configured to be placed in thermal contact with a heat source, the first cylinder having a first surface disposed radially about and extending along a longitudinal axis of the first cylinder; and

a second cylinder disposed coaxially with and rotatably coupled to the first cylinder such that a gas-filled gap region is defined between the first surface of the first cylinder and a second surface of the second cylinder, the second cylinder having a plurality of fins inside the second cylinder and arranged radially about the longitudinal axis, wherein at least one of the plurality of fins has a hollow interior defining a cavity therein, and wherein the second cylinder is configured to rotate about the longitudinal axis.

29. The device of claim 28, wherein the gas-filled gap region has a width when the second cylinder is at rest, and wherein the device is further configured to limit a change in the width of the gas-filled gap region during rotation of the second cylinder.

30. A cylindrical heat pipe for use in a heat exchanger device adapted to transfer heat from a stationary structure to a rotary structure across a gas-filled gap, the heat pipe comprising a pair of concentric cylindrical walls defining a hollow cylindrical region therebetween, the cylindrical heat pipe further having a plurality of hollow fins arranged radially about a centerline of the cylindrical heat pipe and disposed between the pair of cylindrical wall and the centerline, wherein the plurality of hollow fins are interconnected with the hollow cylindrical region of the pair of concentric cylindrical walls to define a heat pipe cavity, and wherein the heat pipe cavity is maintained at partial vacuum.