EVAPORATORS INCLUDING A CAPILLARY WICK AND A PLURALITY OF VAPOR GROOVES AND TWO-PHASE HEAT TRANSFER SYSTEMS INCLUDING SUCH EVAPORATORS

• US 20130220580A1
• Filed: 03/19/2013
• Published: 08/29/2013
• Est. Priority Date: 05/16/2000
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Alliant Techsystems Incorporated (Northrop Grumman Corporation)
• Inventors: Kroliczek, Edward J., Wrenn, Kimberly R., Wolf, David A. Sr.
• Granted Patent: US 9,103,602 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: F28D 15/04 with tubes having a capillary structure
• CPC Class Codes: F28D 15/043 forming loops, e.g. capillary pumped loops
• CPC Class Codes: F28D 15/046 characterised by the material or the construction of the capillary structure
• CPC Class Codes: Y10T 29/49353 Heat pipe device making

Abstract

A two-phase heat transfer system includes an evaporator, a condenser, a vapor line, and a liquid return line. The evaporator includes a liquid inlet, a vapor outlet, and a capillary wick having a first surface adjacent the liquid inlet and a second surface adjacent the vapor outlet. The condenser includes a vapor inlet and a liquid outlet. The vapor line provides fluid communication between the vapor outlet and the vapor inlet. The liquid return line provides fluid communication between the liquid outlet and the liquid inlet. The wick is substantially free of back-conduction of energy from the second surface to the first surface due to an increase in a conduction path from the second surface to the first surface and due to suppression of nucleation of a working fluid from the second surface to the first surface to promote liquid superheat tolerance in the wick.

Claims

1. An evaporator comprising:

a housing for containing a working fluid, the housing having a liquid inlet and a vapor outlet;

a cylindrical capillary wick positioned within the housing and separating the liquid inlet and the vapor outlet, the capillary wick comprising a planar face; and

a plurality of vapor grooves formed in an exterior portion of the capillary wick and located at an interface between the capillary wick and a wall of the housing, the plurality of vapor grooves each extending lengthwise along only a majority of the cylindrical capillary wick in a direction along an axis of the cylindrical capillary wick and perpendicular to the planar face of the capillary wick, wherein the planar face of the capillary wick is sized to entirely fill a portion of the housing adjacent the liquid inlet to require all of the fluid passing through the capillary wick from the liquid inlet to the plurality of vapor grooves to flow through the planar face.

2. The evaporator of claim 1, wherein the pores of the capillary wick have one of a substantially uniform size and a graded size.

4. The evaporator of claim 1, wherein the evaporator is configured to operate in a terrestrial gravitational field.

5. The evaporator of claim 1, wherein the capillary wick is comprised of one of a polymer resin, a polytetrafluoroethylene, and a metal.

9. The evaporator of claim 1, wherein each portion of the cylindrical capillary wick disposed between two adjacent vapor grooves of the plurality of vapor grooves comprises a plurality of lateral grooves extending circumferentially around the cylindrical capillary wick, each lateral groove of the plurality of lateral grooves being relatively smaller in size than each vapor groove of the plurality of vapor grooves.

10. The evaporator of claim 1, wherein each vapor groove of the plurality of vapor grooves is spaced from the planar face of the capillary wick.

11. The evaporator of claim 1, wherein the plurality of vapor grooves comprise a plurality of microchannels.

12. The evaporator of claim 11, wherein the plurality of microchannels are formed by an etching process in the external surface of the capillary wick.

13. The evaporator of claim 1, further comprising a reservoir coupled to the housing for supplying liquid to the capillary wick.

14. The evaporator of claim 13, further comprising a screen positioned between the reservoir and the capillary wick such that liquid flow from the reservoir to the capillary wick flows through the screen.

15. The evaporator of claim 14, further comprising another screen positioned adjacent to the capillary wick and between the screen and the capillary wick such that the liquid flow from the reservoir to the capillary wick flows through the another screen.

16. The evaporator of claim 13, wherein the reservoir comprises a diffuser and a liquid return line, the diffuser for supplying liquid from the liquid return line into the reservoir.

17. The evaporator of claim 16, wherein the diffuser comprises a plurality of radial channels for supplying liquid from the liquid return line into the reservoir.

3. (canceled)

6-8. -8. (canceled)

18. An evaporator comprising:

a housing for containing a working fluid, the housing having a liquid inlet and a vapor outlet;

a cylindrical capillary wick positioned within the housing and separating the liquid inlet and the vapor outlet, the capillary wick comprising a planar face;

a plurality of vapor grooves formed at an interface between an exterior portion of the capillary wick and a wall of the housing, the plurality of vapor grooves each extending lengthwise along a majority of the cylindrical capillary wick in a direction along an axis of the cylindrical capillary wick and perpendicular to the planar face of the capillary wick, wherein the planar face of the capillary wick is sized to entirely fill a portion of the housing adjacent the liquid inlet to require all of the fluid passing through the capillary wick from the liquid inlet to the plurality of vapor grooves to flow through the planar face; and

a plurality of lateral grooves extending circumferentially around the cylindrical capillary wick at each portion of the cylindrical capillary wick disposed between two adjacent vapor grooves of the plurality of vapor grooves, each lateral groove of the plurality of lateral grooves being relatively smaller in size than each vapor groove of the plurality of vapor grooves.

19. The evaporator of claim 18, wherein the plurality of vapor grooves comprise grooves in an external surface of the capillary wick.

20. The evaporator of claim 18, wherein the plurality of lateral grooves comprise grooves in the external surface of the capillary wick.

21. The evaporator of claim 18, wherein the plurality of vapor grooves comprise a plurality of microchannels.

22. The evaporator of claim 18, further comprising a reservoir coupled to the housing for supplying liquid to the capillary wick.

23. An evaporator comprising:

a housing for containing a working fluid, the housing having a liquid inlet and a vapor outlet;

a cylindrical capillary wick positioned within the housing and separating the liquid inlet and the vapor outlet, the capillary wick comprising a planar face;

a plurality of vapor grooves formed at an interface between an exterior portion of the capillary wick and a wall of the housing, the plurality of vapor grooves each extending lengthwise along only a majority of the cylindrical capillary wick in a direction along an axis of the cylindrical capillary wick and perpendicular to the planar face of the capillary wick such that each vapor groove of the plurality of vapor grooves is spaced from the planar face of the capillary wick, and wherein the planar face of the capillary wick is sized to entirely fill a portion of the housing adjacent the liquid inlet to require all of the fluid passing through the capillary wick from the liquid inlet to the plurality of vapor grooves to flow through the planar face.