Wick having liquid superheat tolerance and being resistant to back-conduction, evaporator employing a liquid superheat tolerant wick, and loop heat pipe incorporating same
View Patent ↗A capillary wick for use in capillary evaporators has properties that prevent nucleation inside the body of the wick, resulting in suppression of back-conduction of heat from vapor channels to the liquid reservoir. Use of a central liquid flow channel in the wick is eliminated, and pore size in the wick is chosen to maximize available pressure for fluid pumping, while preventing nucleation in the wick body. The wick is embodied with different geometries, including cylindrical and flat. A flat capillary evaporator has substantially planar heat input surfaces for convenient mating to planar heat sources. The flat capillary evaporator is capable of being used with working fluids having high vapor pressures (i.e., greater that 10 psia). To contain the pressure of the vaporized working fluid, the opposed planar plates of the evaporator are brazed or sintered to opposing sides of a metal wick. Additionally, a terrestrial loop heat pipe and a loop heat pipe having overall flat geometry are disclosed.
1. A cooling device comprising:
a heat sink having a heat receiving face; and
a heat transfer system adjacent the face of the heat sink, the heat transfer system comprising:
a component mounting face sheet;
an evaporator disposed on the component mounting face sheet and comprising:
a capillary wick, and
vapor grooves formed between the component mounting face sheet and the capillary wick;
a fluid reservoir disposed between the evaporator and the heat sink;
a condenser comprising plural condenser flow channels disposed in the component mounting face sheet;
one or more vapor flow channels providing fluid connection between the vapor grooves and the condenser flow channels; and
one or more liquid return channels providing fluid connection between the condenser flow channels and the fluid reservoir;
wherein heat generating components to be cooled are configured to be mounted on the component mounting face sheet.
2. The cooling device of claim 1 wherein the heat transfer system is embedded in the face of the heat sink, and the capillary wick is contained within the evaporator and segregated from the condenser.
3. The cooling device of claim 2 , wherein the heat transfer system operates reliably in a terrestrial gravitational field.
4. The cooling device of claim 2 , further comprising a working fluid within the heat transfer system.
5. The cooling device of claim 1 , wherein the liquid return channels are positioned between the heat sink and the component mounting face sheet.
6. The cooling device of claim 1 , wherein the vapor grooves are formed in the component mounting face sheet.
7. The cooling device of claim 1 , wherein the vapor grooves are formed in the capillary wick.
8. The cooling device of claim 1 , wherein the heat transfer system includes a reservoir positioned adjacent the capillary wick.
9. The cooling device of claim 8 , wherein the reservoir is in fluid communication with the capillary wick.
10. The cooling device of claim 1 , further comprising a working fluid within the heat transfer system.
11. The cooling device of claim 1 , wherein the evaporator is positioned between the component mounting face sheet and the heat sink.
12. A cooling device comprising:
a heat sink having a heat receiving face; and
a heat transfer system adjacent the face of the heat sink, the heat transfer system comprising:
a component mounting face sheet;
an evaporator disposed on the component mounting face sheet and comprising:
a capillary wick, and
vapor grooves formed between the component mounting face sheet and the capillary wick; and
a condenser coupled to the evaporator; wherein the condenser is positioned within the component mounting face sheet.
13. The cooling device of claim 12 , wherein the heat transfer system includes a vapor flow channel providing fluid connection between the vapor grooves within the evaporator and condenser flow channels within the condenser.
14. The cooling device of claim 12 , wherein the heat transfer system includes a liquid return channel providing fluid connection between condenser flow channels within the condenser and a reservoir coupled to the evaporator.
15. The cooling device of claim 13 , wherein the capillary wick is configured to prevent nucleation of a working fluid inside the wick body.
16. The cooling device of claim 12 , wherein the heat transfer system is embedded in the face of the heat sink, and the capillary wick is contained within the evaporator and segregated from the condenser.
17. The cooling device of claim 12 , wherein the capillary wick is configured to prevent nucleation of a working fluid inside the wick body.
18. The cooling device of claim 12 , wherein the heat transfer system operates reliably in a terrestrial gravitational field.
19. The cooling device of claim 12 , further comprising a working fluid within the heat transfer system.
20. The cooling device of claim 12 , wherein the vapor grooves are formed in the component mounting face sheet.
21. The cooling device of claim 12 , wherein the vapor grooves are formed in the capillary wick.
22. The cooling device of claim 12 , wherein the heat transfer system includes a reservoir positioned adjacent the capillary wick.
23. The cooling device of claim 22 , wherein the reservoir is in fluid communication with the capillary wick.
24. The cooling device of claim 12 , wherein the evaporator is positioned between the component mounting face sheet and the heat sink.
25. A cooling device comprising:
a heat sink having a heat receiving face; and
a heat transfer system embedded in the face of the heat sink, the heat transfer system comprising:
a component mounting face sheet;
a condenser including a condenser flow channel;
a fluid reservoir disposed between the evaporator and the heat sink;
an evaporator disposed on the component mounting face sheet and comprising:
a capillary wick contained within the evaporator and segregated from the condenser; and
vapor grooves formed between the component mounting face sheet and the capillary wick;
a vapor flow channel providing fluid connection between the vapor grooves and the condenser flow channel; and
a liquid return channel providing fluid connection between the condenser flow channel and the fluid reservoir;
wherein the condenser flow channel is connected to one of the liquid return channel via a capillary flow regulator.
26. The cooling device of claim 25 , wherein the capillary flow regulator is micromachined into the component mounting face sheet.
27. A cooling device comprising:
a heat sink having a heat receiving face; and
a heat transfer system embedded in the face of the heat sink, the heat transfer system comprising:
a component mounting face sheet;
a condenser including a condenser flow channel;
a fluid reservoir disposed between the evaporator and the heat sink;
an evaporator disposed on the component mounting face sheet and comprising:
a capillary wick contained within the evaporator and segregated from the condenser; and
vapor grooves formed between the component mounting face sheet and the capillary wick;
a vapor flow channel fluidly coupled to the vapor grooves and the condenser flow channel; and
a liquid return channel fluidly coupled to the fluid reservoir and the condenser flow channel;
wherein the vapor flow channel, the liquid return channel, and the condenser flow channel are substantially co-planar with one another.