Patent Application
20080307651
Many heat pipe devices and methods exist for dissipating heat from a heat source. For instance, in one existing heat pipe device, a closed chamber is used. The closed chamber has a porous wick layer extending around a perimeter of the inner surface of the chamber. In the center of the chamber is an empty cavity. The chamber is filled with a saturated working fluid with liquid only existing in the voids of the wick. When heat is applied in an evaporator area, the liquid in the evaporator wick vaporizes and fills the center cavity. Since the opposite side of the evaporator is cooled, the vapor condenses on that side. The condensed liquid is wicked back to the evaporator by capillary force. However, this type of structure or process, or other types of existing structures or processes, may experience one or more problems in practical applications, especially for high power density electronics. The problems may include insufficient structure strength, low capacity, low tolerance to local heat fluxes at hot spots, poor performance at high heat flux conditions, complex internal constructions, high manufacturing costs, and/or one or more other types of problems.
A device, method of use, and/or method of manufacture is needed to decrease one or more problems associated with one or more of the existing devices and/or methods for dissipating heat from a heat source.
In one aspect of the disclosure, a device is provided for dissipating heat from a heat source. The device comprises a porous wick structure comprising a first porous wick portion disposed adjacent to a second porous wick portion. The first porous wick portion is defined by a first set of microgrooves. The second porous wick portion is defined by a second set of microgrooves disposed in non-parallel adjacent alignment to the first set of microgrooves.
In another aspect of the disclosure, a method of dissipating heat from a heat source is disclosed. In one step, a porous wick structure is provided having a first porous wick portion disposed adjacent to a second porous wick portion. The first porous wick portion is defined by a first set of microgrooves disposed in non-parallel adjacent alignment to a second set of microgrooves defined in the second porous wick portion. In another step, a surface of the porous wick structure is disposed at least one of against and near a heat source. In still another step, saturated fluid is charged within first porous walls of the first set of microgrooves and second porous walls of the second set of microgrooves. In yet another step, some of the fluid is evaporated near the surface of the porous wick structure to form a vapor and dissipate heat from the heat source. In an additional step, vapor is flowed between and within the adjacent second and first sets of microgrooves. In another step, the vapor is condensed into a liquid away from the surface of the porous wick structure. In still another step, the condensed liquid is flowed to at least one of the first and second porous walls.
In a further aspect of the disclosure, a method is disclosed of manufacturing a device for dissipating heat from a heat source. In one step, a first porous wick portion is molded so that it is defined by a first set of microgrooves. In another step, a second porous wick portion is molded so that it is defined by a second set of microgrooves. In still another step, the first porous wick portion is disposed adjacent to the second porous wick portion so that the first set of microgrooves is disposed in non-parallel adjacent alignment to the second set of microgrooves. In an additional step, the first and second porous wick portions are sintered together.
In still another aspect of the disclosure, a vapor chamber is provided for transferring heat with an internal working fluid. The vapor chamber comprises a sealed enclosure having interior walls which contain a wick material attached to at least one of the walls. The wick material includes a first portion oriented in a first direction and a second portion oriented in a second direction different than the first direction. The working fluid is free to travel in both the first and second directions.
These and other features, aspects and advantages of the disclosure will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out the disclosure. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the disclosure, since the scope of the disclosure is best defined by the appended claims.
Similarly, the second porous wick portion 18 may be defined by a second set of microgrooves 30 which may extend in a parallel configuration from one end 32 to another end 34 of the second porous wick portion 18. Each of the microgrooves 30 may be defined by opposing side second porous walls 36 and 38. As shown, the second set of microgrooves 30 may be of the same size as the first set of microgrooves 20. In other embodiments, the second porous wick portion 18 may have a second set of microgrooves 30 which are of varying sizes, orientations, and/or configurations.
As shown in
When heat is applied at hop spot 48 at or near the surface 13 of the device 10 which is attached to a hear source 12, the saturated liquid 40 residing within the porous sub-layer 37 and second porous walls 36 and 38 may evaporate at vapor/liquid interfaces within sub-layer 37 and second porous walls 36 and 38, or may boil near the hot spot 48 and form a vapor 50. The vapor 50 may flow through the pores 44 of the porous sub-layer 37 if boiling takes place and may subsequently enter the second set of microgrooves 30 as shown by representative directions 52 and 53. In other embodiments, the vapor 50 may flow in any direction out of the pores 42 and 44 of each of the first and second porous walls 26, 28, 36, and 38. The vapor 50 may flow within and between the second set of microgrooves 30 and the interconnected first set of microgrooves 20 in representative direction 54. In other embodiments, the vapor 50 may flow in any direction within and between the first and second sets of microgrooves 20 and 30.
When the vapor 50 is far enough away from the hot spot 48, for instance at representative area 56 within the first set of microgrooves 20, the vapor 50 may condense into a fluid 58. In other embodiments, the vapor 50 may condense back into a liquid at any contact surface within the first and second set of microgrooves 20 and 30 that is colder than the hot spot 48. The capillary forces generated by the pores 42 and 44 may return the condensed liquid 58 from the colder area 56, through the pores 42, and 44, and back to the hot spot area 48.
The condensed fluid 58 may then re-circulate through, between, and within the pores 42 and 44 of the first and second porous walls 26, 28, 36, and 38, in order to repeat the process and continue to cool hot spots 48. In other embodiments, the condensed fluid 58 may re-circulate through, between, and within the pores 42 and 44 of the first and second porous walls 26, 28, 36, and 38 in any direction in order to cool hot spots 48.
In another embodiment, a vapor chamber 15 may be provided for transferring heat with an internal working fluid 40. The vapor chamber 15 may comprise a sealed enclosure having interior walls and containing a porous wick material 14 attached to at least one interior wall of the vapor chamber 15. The porous wick material 14 may include a first portion 16 oriented in a first direction, and a second portion 18 oriented in a second direction different than the first direction. The first and second portions 16 and 18 may be interlocked to provide a stronger structure to withstand the internal to external pressure differential. As a result, the vapor chamber 15 may be sturdier, may be made more lightweight by thinner walls, and/or may avoid the need for additional supporting structures.
Each of the respective first and second portions 16 and 18 may have respective microgrooves 20 and 30 which define the direction of orientation. The microgrooves 20 and 30 may be regular in size and straight, or in other embodiments may be irregular and curvy. In one embodiment, the first and second directions of the first and second portions 16 and 18 may be substantially perpendicular. In other embodiments, the first and second directions may be in varying orientations and configurations relative to one another. In still other embodiments, more than two portions may be used with more than two directions to provide increased heat transfer in a plurality of directions. The fluid 40 may be free to travel within the porous wick material 14 in both of the first and second directions. In such manner, by providing fluid travel in two or more directions, the heat transfer effectiveness may be improved. Vapor 50 may more readily escape from heated spots 13 through the sets of microgrooves 20 and 30.
In one embodiment, the first and second sets of microgrooves 20 and 30 may be disposed in substantially perpendicular adjacent alignment. The first and second sets of microgrooves 20 and 30 may be interconnected so that a vapor 50 may flow between the first and second sets of microgrooves 20 and 30. The first porous walls 26 and 28 of the first set of microgrooves 20 may be interconnected to the second porous walls 36 and 38 of the second set of microgrooves 30 so that a fluid 40 may flow between and within the first and second porous walls 26, 28, 36, and 38.
In step 168, a surface 13 of the porous wick structure 14 may be disposed against a heat source 12. In step 170, a proper amount of saturated working fluid may be charged into the closed chamber with liquid phase 40 residing only within the first porous walls 26 and 28 of the first set of microgrooves 20 and the second porous walls 36 and 38 of the second set of microgrooves 30. In step 172, some of the liquid 40 may evaporate at or near the surface 13 of the porous wick structure 14 to dissipate heat from the heat source 12 and form a vapor 50. In step 174, the vapor 50 may flow between and within the adjacent second and first sets of microgrooves 30 and 20. In step 176, the vapor 50 may be condensed into a condensed fluid 58 at a contact surface 56 that is colder than the surface 13. In step 178, the condensed fluid 58 may flow into the first porous walls 26 and 28, the second porous walls 36 and 38, and/or the porous sub-layer 37.
In step 286, the first porous wick portion 16 may be disposed adjacent to the second porous wick portion 18 so that the first set of microgrooves 20 is disposed in non-parallel, adjacent alignment to the second set of microgrooves 30. In step 288, the first and second porous wick portions 16 and 18, including the first and second sets of microgrooves 20 and 30, may be sintered together. In one embodiment, the sintering may occur at substantially 950-1,000 degrees Celsius. In other embodiments, the sintering may occur at varying temperatures.
After the first and second wick portions 20 and 30 are sintered together, they may be fixedly disposed in a non-parallel, adjacent alignment, such as in a perpendicular, adjacent alignment. At this time, the first and second sets of microgrooves 20 and 30 may be fixedly disposed so that they are interconnected to allow vapor 50 to flow within and between the first and second sets of microgrooves 20 and 30. Similarly, at this time, the first porous walls 26 and 28 of the first set of microgrooves 20, and the second porous walls 36 and 38 of the second set of microgrooves 30 may be fixedly disposed so that they are interconnected to allow fluid 40 to flow within and between the first and second porous walls 26, 28, 36, and 38. The first and second wick portions 20 and 30 may be inserted within a closed chamber enclosure 15.
One or more embodiments of the disclosure may provide one or more of the following advantages over one or more of the existing devices and/or methods: increased capillary limits; increased heat flux; increased structure strength; decreased size or weight; decreased complexity; decreased manufacturing costs; increased efficiency; increased cooling; and/or one or more other types of advantages over one or more of the existing devices and/or methods.
It should be understood, of course, that the foregoing relates to exemplary embodiments of the disclosure and that modifications may be made without departing from the spirit and scope of the disclosure as set forth in the following claims.
