The present invention relates generally to a heat pipe and a method for manufacturing the heat pipe, and more particularly to a heat pipe having a sintered wick structure and a method for manufacturing such a heat pipe.
Heat pipes have excellent heat transfer performance due to their low thermal resistance, and therefore are an effective means for transferring or dissipating heat from heat sources. Currently, the heat pipes are widely used for removing heat from heat-generating components such as central processing units (CPUs) of computers. A heat pipe is generally a vacuum-sealed pipe. A wick structure is provided on an inner wall of the pipe, and the pipe contains at least a phase changeable working media employed to carry heat. Generally, according to positions from which heat is input or output, the heat pipe has three sections: an evaporating section, a condensing section and an adiabatic section between the evaporating section and the condensing section.
In use, the heat pipe transfers heat from one place to another place mainly by virtue of phase change of the working media taking place therein. Generally, the working media is a liquid such as alcohol, water and so on. When the working media in the evaporating section of the heat pipe is heated up, it evaporates, and a pressure difference is thus produced between the evaporating section and the condensing section in the heat pipe. Resultant vapor with high enthalpy rushes to the condensing section and condenses there. Then the condensed liquid reflows to the evaporating section along the wick structure. This evaporating/condensing cycle repeats in the heat pipe. As a consequence of this heat can be continually transferred from the evaporating section to the condensing section. Due to the continual phase change of the working media, the evaporating section is kept at or near the same temperature as the condensing section of the heat pipe. The heat pipe is used widely owing to its great heat-transfer capability.
In the heat pipe, the reflowing condensed liquid is resisted by ascending vapor from the evaporating section; this results in volume of reflowing liquid decreasing, which can lead to dry-out in the evaporating section of the heat pipe. Additionally, due to large ratio of length to radius, large amounts of heat from the vapor is dissipated to ambient air on the way to the condensing section of the heat pipe. Therefore, the vapor is condensed before arrival at the condensing section, which blocks ascension of the vapor to the condensing section. As a result, heat transfer capability of heat pipe can be adversely affected.
Therefore, it is desirable to provide a heat pipe which has greater heat transfer capability.
A heat pipe in accordance with an embodiment of the present invention comprises a pipe containing phase changeable working media therein. A wick structure is located on an inner face of the pipe. A space is surrounded by the wick structure in the pipe. At least one muzzle with an inlet and an outlet is positioned in the space of the pipe; the inlet and the outlet are different in radius.
Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which:
Many aspects of the present apparatus and method can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present apparatus and method. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
According to positions from which heat is input or output, the heat pipe is defined with an evaporating section 400, a condensing section 600, and an adiabatic section 500 located between the evaporating section 400 and the condensing section 600.
The muzzle 300 is positioned adjacent to a joint of the evaporating section 400 and the adiabatic section 500, with an inlet 310 thereof extending toward and facing the evaporating section 400 and an outlet 320 thereof extending toward and facing the adiabatic section 500 and the condensing section 600. Still, the muzzle 300 can be entirely positioned at the adiabatic section 500 or the evaporating section 400. The muzzle 300 is tapered from the inlet 310 to the outlet 320, where a diameter of the outlet 320 is smaller than that of the inlet 310; that is to say, the outlet 320 has a cross-sectional area smaller than that of the inlet 310. According to principle of continuity of fluid that a product (Q: denoting a volume of a fluid flowing through a cross section of a pipe per second) of an area (S) of any cross section and a velocity (V) of a fluid flowing through corresponding cross section in a same pipe is a constant. Therefore, according to the equation of continuity of fluid: Q=S*V, it is known that the fluid has a larger velocity in the smaller area while it has a smaller velocity in the larger area. For the muzzle 300 of the heat pipe, the evaporated working media has a larger velocity at the outlet 320; therefore, the evaporated working media is accelerated by the muzzle 300 to flow to the condensing section 600. In use, the evaporating section 400 absorbs heat from a heat source, the working media in the evaporating section 400 is heated up, it evaporates, and pressure difference is thus produced between the evaporating section 400 and the condensing section 600. Resultant vapor with high enthalpy rushes to the muzzle 300, and passes through the muzzle 300 from the inlet 310 to the outlet 320 to thereby be accelerated with a larger velocity rushing to the condensing section 600 via the adiabatic section 500. The vapor releases heat to ambient air and is condensed at the condensing section 600. Then the condensed liquid reflows to the evaporating section 400 along the wick structure 200. This evaporating/condensing cycle repeats in the heat pipe.
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It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Number | Date | Country | Kind |
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2006 1 0034172 | Mar 2006 | CN | national |
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53088255 | Aug 1978 | JP |
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Number | Date | Country | |
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20070204975 A1 | Sep 2007 | US |