Variable-conductance heat transfer device
View Patent ↗A heat transfer device is provided for conducting heat from a heat source. The heat transfer device generally includes an evaporator for generating a vapor, a condenser in fluid communication with the evaporator, and a vapor flow restrictor interposed between the evaporator and the condenser, wherein the vapor flow restrictor can increase vapor pressure in at least a portion of the evaporator relative to vapor pressure in the condenser.
1. A heat transfer device for conducting heat from a heat source, the heat transfer device having a longitudinal axis and comprising:
an evaporator for generating a vapor, the evaporator defined by at least one wall;
a condenser in fluid communication with the evaporator, the condenser defined by at least one wall, wherein the walls that define the evaporator and the condenser together define an interior space; and
a vapor flow restrictor interposed between the evaporator and the condenser,
wherein the vapor flow restrictor has opposed planar surfaces each orthogonal to the longitudinal axis of the heat transfer device and an orifice of constant cross section extending between the opposed planar surfaces, wherein the orifice defines a vapor flow path between the evaporator and condenser, wherein the vapor flow path is unobstructed through the orifice at all operating temperatures,
wherein the vapor flow restrictor increases vapor pressure in at least a portion of the evaporator relative to vapor pressure in the condenser,
wherein the vapor flow restrictor is configured to decrease the vapor flow rate from the evaporator to the condenser as the evaporator temperature decreases,
wherein vapor passes from the evaporator toward the condenser through the vapor flow restrictor, and
wherein condensed working fluid passes in the interior space from the condenser back toward the evaporator past the vapor flow restrictor.
2. The heat transfer device of claim 1 having a working fluid therein, wherein the vapor flow restrictor permits flow of the working fluid therepast.
3. The heat transfer device of claim 1 , wherein at least a portion of an interior surface of one of the walls has wick material attached hereto.
4. The heat transfer device of claim 3 , wherein the vapor flow restrictor has a perimeter and wherein the perimeter of the vapor flow restrictor is in contact with at least a portion of the wick material.
5. The heat transfer device of claim 4 , wherein flow of working fluid is permitted through the wick material adjacent the vapor flow restrictor.
6. The heat transfer device of claim 5 , wherein the vapor flow restrictor is adjacent the evaporator.
7. The heat transfer device of claim 1 , wherein the heat transfer device comprises a primary part and a secondary part separated by a separating wall, wherein the orifice is located in the separating wall.
8. The heat transfer device of claim 1 , wherein at least a portion of one of the walls has wick material attached thereto, and wherein the wick material comprises a constriction that defines the vapor flow restrictor.
9. The heat transfer device of claim 1 , wherein the vapor is substantially free of non-condensable gas.
10. A heat transfer device for conducting heat from a heat source, the heat transfer device comprising:
an evaporator for generating a vapor, the evaporator defined by at least one wall;
a condenser in fluid communication with the evaporator, the condenser defined by at least one wall, wherein the walls that define the evaporator and the condenser together define an interior space; and
a vapor flow restrictor interposed between the evaporator and the condenser,
wherein the vapor flow restrictor is positioned adjacent the evaporator,
wherein the vapor flow restrictor has opposed planar surfaces with an orifice extending between the opposed planar surfaces, the orifice having an inlet and an outlet, the inlet and the outlet being each disposed in one of the opposed planar surfaces, respectively, and having cross-sectional areas of equal size, wherein the orifice defines a vapor flow path between the evaporator and condenser, wherein the vapor flow path is unobstructed through the orifice at all operating temperatures,
wherein the vapor flow restrictor is configured to vary the vapor flow rate from the evaporator to the condenser and thereby maintain the temperature of the heat source within a predetermined range,
wherein vapor passes from the evaporator toward the condenser through the vapor flow restrictor, and
wherein condensed working fluid passes in the interior space from the condenser back toward the evaporator past the vapor flow restrictor.
11. The heat transfer device of claim 10 , wherein the vapor flow restrictor is positioned no more than half way from the evaporator to the condenser.
12. The heat transfer device of claim 10 , wherein the orifice is located in the vapor flow restrictor such that the orifice is located approximately at a center of the heat transfer device.
13. The heat transfer device of claim 10 , wherein the vapor flow restrictor defines a vapor flow restrictor diameter, the orifice defines an orifice diameter, and the orifice diameter is 0.5% to 15% of the vapor flow restrictor diameter.
14. The heat transfer device of claim 10 , wherein at least a portion of the vapor flow restrictor is fixedly connected to one of the walls.
15. The heat transfer device of claim 10 , wherein the vapor flow restrictor includes a plurality of tabs, the tabs connecting the vapor flow restrictor to an interior surface of one of the walls.
16. The heat transfer device of claim 15 , wherein the tabs at least partially define at least one gap between the vapor flow restrictor and the one of the walls, wherein the vapor is condensed at the condenser to form a working fluid, and wherein at least a portion of the working fluid is returned to the evaporator through the gap.
17. The heat transfer device of claim 10 , wherein the heat transfer device further comprises a wick disposed on at least a portion of an interior surface of one of the walls.
18. The heat transfer device of claim 17 , wherein the vapor flow restrictor at least a portion of the wick.
19. The heat transfer device of claim 18 , wherein the wick forms a constriction that defines the orifice in the vapor flow restrictor.
20. The heat transfer device of claim 10 , wherein one of the walls has a wick disposed on at least a portion of an interior surface of the wall and the vapor flow restrictor has a perimeter in contact with the wick.
21. The heat transfer device of claim 10 , wherein the vapor flow restrictor increases vapor pressure in at least a portion of the evaporator relative to vapor pressure in the condenser.
22. The heat transfer device of claim 10 , further comprising a working fluid, wherein the vapor flow restrictor permits the working fluid to flow between the condenser and the evaporator.
23. The heat transfer device of claim 10 , wherein the vapor flow restrictor is positioned at no more than one-third of the way from the evaporator to the condenser.
24. The heat transfer device of claim 10 , wherein the vapor is substantially free of non-condensable gas.
25. The heat transfer device of claim 10 , wherein the evaporator is connected to the condenser in a closed loop.
26. The heat transfer device of claim 10 , wherein the temperature of the heat source is maintained at a relatively constant temperature independent of the temperature of the condenser.
27. The heat transfer device of claim 10 , wherein the orifice is of constant size through the vapor flow restrictor.
28. A heat transfer device for conducting heat from a heat source, the heat transfer device comprising:
an evaporator defined by at least one wall;
a condenser in fluid communication with the evaporator, the condenser defined by at least one wall, wherein the walls that define the evaporator and the condenser together define an interior space;
a wick disposed on at least a portion of an interior surface of one of the walls, the wick having a working fluid in contact therewith in a liquid form; and
a vapor flow restrictor interposed between the evaporator and the condenser, the vapor flow restrictor having an orifice that defines a vapor flow path between the evaporator and condenser, wherein the vapor flow path is unobstructed through the orifice at all operating temperatures,
wherein the vapor flow restrictor is positioned adjacent the evaporator,
wherein the entire vapor flow restrictor is fixed in position to prevent movement of any portion of the vapor flow restrictor relative to the walls
wherein the vapor flow restrictor is configured to vary the vapor flow rate from the evaporator to the condenser and thereby decrease the amount of power transmitted from the evaporator to the condenser as the temperature of the evaporator decreases,
wherein vapor passes from the evaporator toward the condenser through the vapor flow restrictor, and
wherein condensed working fluid passes in the interior space from the condenser back toward the evaporator past the vapor flow restrictor.
29. The heat transfer device of claim 28 , wherein the vapor flow restrictor is positioned at no more than half way from the evaporator to the condenser.
30. The heat transfer device of claim 28 , wherein the vapor flow restrictor comprises a perimeter and wherein the perimeter of the vapor flow restrictor is in contact with the wick such that substantially all of the vapor passes through the orifice.
31. The heat transfer device of claim 28 , wherein the vapor flow restrictor is in contact with at least one portion of the interior surface.
32. The heat transfer device of claim 28 , wherein the vapor flow restrictor increases vapor pressure in at least a portion of the evaporator relative to vapor pressure in the condenser.
33. The heat transfer device of claim 28 , wherein the wick is disposed in both the evaporator and the condenser.
34. The heat transfer device of claim 33 , wherein the working fluid flows between the evaporator and the condenser via the wick.
35. The heat transfer device of claim 28 , wherein the vapor is substantially free of non-condensable gas.
36. The heat transfer device of claim 28 , wherein the vapor flow restrictor is positioned no more than one-third of the way from the evaporator to the condenser.
37. The heat transfer device of claim 28 , wherein the heat transfer device has a longitudinal axis and the plate is orthogonal to the axis.
38. The heat transfer device of claim 28 , wherein the opening has an inlet and an outlet having cross-sectional areas of equal size.
39. The heat transfer device of claim 28 , wherein the opening has a constant cross section extending through the plate.
40. A heat transfer device for conducting heat from a heat source, the heat transfer device comprising:
an evaporator for generating a vapor;
a condenser in fluid communication with the evaporator; and
a vapor flow restrictor interposed between the evaporator and the condenser,
wherein the vapor flow restrictor is positioned adjacent the evaporator and has opposed surfaces that are parallel to one another with an unrestricted opening of constant cross section extending between the opposed surfaces, the opening having an inlet and an outlet, the inlet and the outlet being each disposed in one of the opposed outer surfaces, respectively, and having cross-sectional areas of equal size, and
wherein as the temperature of the evaporator varies, the vapor flow restrictor is configured to vary the vapor flow rate from the evaporator to the condenser through an orifice the defines a vapor flow path between the evaporator and condenser, wherein the vapor flow path is unobstructed through the orifice at all operating temperatures and thereby vary the temperature differential between the evaporator and condenser to maintain the heat source toward a constant temperature,
wherein vapor passes from the evaporator toward the condenser through the vapor flow restrictor, and
wherein condensed working fluid flows back toward the evaporator in an area defined between a periphery of the vapor flow restrictor and an interior wall of the heat transfer device.
41. The heat transfer device of claim 40 , wherein the vapor flow restrictor increases vapor pressure in at least a portion of the evaporator relative to vapor pressure in the condenser.
42. The heat transfer device of claim 40 , wherein the vapor flow restrictor is positioned at no more than half way from the evaporator to the condenser.
43. The heat transfer device of claim 40 , wherein the vapor flow restrictor comprises a plate.
44. The heat transfer device of claim 40 , wherein the heat transfer device has a longitudinal axis and the opposed outer surfaces are orthogonal to the longitudinal axis of the heat transfer device.
45. The heat transfer device of claim 40 , wherein the vapor flow restrictor has an opening with an inlet and an outlet having cross-sectional areas of equal size.
46. The heat transfer device of claim 40 , wherein the opening has a constant size extending through the vapor flow restrictor.
47. A method of conducting heat from a heat source, the method comprising:
providing a heat transfer device including an evaporator for generating a vapor, and a condenser in fluid communication with the evaporator;
providing a wick on at least a portion of an interior surface of the heat transfer device;
interposing a vapor flow restrictor between the evaporator and the condenser, wherein the vapor flow restrictor is positioned adjacent the evaporator and is formed entirely of the wick; and
decreasing the amount of power transmitted from the evaporator to the condenser as the temperature of the evaporator decreases to vary the temperature differential between the evaporator and condenser and thereby maintain the heat source within a predetermined operating range.
48. A heat transfer device for conducting heat from a heat source, the heat transfer device comprising:
an evaporator;
a condenser in fluid communication with the evaporator, at least one of the evaporator and condenser at least partially defining a wall of an interior space of the heat transfer device;
a wick disposed on at least a portion of an interior surface of the wall, the wick having a working fluid in contact therewith in a liquid form; and
a vapor flow restrictor interposed between the evaporator and the condenser,
wherein the vapor flow restrictor is positioned adjacent the evaporator,
wherein the entire vapor flow restrictor has an orifice that defines a vapor flow path between the evaporator and condenser, wherein the vapor flow path is unobstructed through the orifice at all operating temperatures,
wherein the vapor flow restrictor is configures to vary the vapor flow rate from the evaporator to the condenser and thereby decrease the amount of power transmitted from the evaporator to the condenser as the temperature of the evaporator decreases,
wherein vapor passes from the evaporator toward the condenser through the vapor flow restrictor, and
wherein condensed working fluid flows back toward the evaporator in an area between a periphery of the vapor flow restrictor and a portion of the wall.
49. The heat transfer device of claim 48 , wherein the vapor flow restrictor is positioned at no more than half way from the evaporator to the condenser.
50. The heat transfer device of claim 48 , wherein the vapor flow restrictor includes a plate, wherein the plate comprises a perimeter and wherein the perimeter of the plate is in contact with the wick such that substantially all of the vapor passes through the opening in the plate.
51. The heat transfer device of claim 48 , wherein the vapor flow restrictor includes a plate, wherein the plate is in contact with at least one portion of the interior surface of the wall.
52. The heat transfer device of claim 48 , wherein the vapor flow restrictor increases vapor pressure in at least a portion of the evaporator relative to vapor pressure in the condenser.
53. The heat transfer device of claim 48 , wherein the wick is disposed in both the evaporator and the condenser.
54. The heat transfer device of claim 53 , wherein the working fluid flows between the evaporator and the condenser via the wick.
55. The heat transfer device of claim 48 , wherein the vapor is substantially free of non-condensable gas.
56. The heat transfer device of claim 48 , wherein the vapor flow restrictor is positioned no more than one-third of the way from the evaporator to the condenser.