Abstract:
A heat dissipation apparatus includes an evaporator receiving heat from a heat source, a condenser releasing the heat of the heat source, and a pipeline inter connecting the evaporator and the condenser. The condenser defines a flat rectangular chamber therein. A working fluid is contained in the evaporator. The working fluid vaporizes upon receiving the heat of the heat source. The pipeline conducts the vaporized working fluid from the evaporator to the condenser. The vaporized working fluid condenses upon releasing the heat in the chamber.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure generally relates to heat dissipation, and particularly to a heat dissipation apparatus with a heat pipe. 
         [0003]    2. Description of Related Art 
         [0004]    A typical heat pipe often used for heat dissipation includes a vacuum casing containing a working fluid. Preferably, a wick structure is provided inside the heat pipe, lining an inner wall of the casing. The heat pipe has an evaporating section for absorbing heat from a heat source such as a heat-generating electronic component, and a condensing section for releasing the heat absorbed by the evaporating section. When the heat is introduced to the heat pipe at the evaporating section thereof, the working fluid contained therein absorbs the heat and vaporizes. Due to the difference in vapor pressure between the two sections of the heat pipe, the generated vapor moves, bearing the heat, towards the condensing section. The vapor is condensed at the condensing section, whereby the heat is released into the ambient environment or, for example, transferred to a heat sink thermally attached to the condensing section. Due to the difference in capillary pressure of the wick structure between the two sections of the heat pip, the condensate is then drawn back by the wick structure to the evaporating section where it is again available for evaporation. 
         [0005]    To increase the contact area between the condensing section of the heat pipe and the heat sink and thereby accelerate condensation, the condensing section of the heat pipe is usually curved or staved. However, such changes normally destroy the wick structure of the heat pipe and increase a flow resistance of the vapor in the heat pipe. This negative effect reduces the speed at which the condensate can reach the evaporating section of the heat pipe. If the condensate is not promptly returned to the evaporating section, the heat pipe will suffer drying. 
         [0006]    Therefore, what is needed is a heat dissipation apparatus which can overcome the described limitations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is an isometric, assembled view of a first embodiment of a heat dissipation apparatus. 
           [0008]      FIG. 2  is an exploded view of the heat dissipation apparatus of  FIG. 1 . 
           [0009]      FIG. 3  is an enlarged view of a circled portion III of  FIG. 2 . 
           [0010]      FIG. 4  is an isometric, assembled view of a second embodiment of a heat dissipation apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Referring to  FIGS. 1 and 2 , a first embodiment of a heat dissipation apparatus  100  according to the disclosure is shown. The heat dissipation apparatus  100  is configured for dissipating heat from an electronic component (not shown), such as a CPU (central processing unit) of a portable computer. The heat dissipation apparatus  100  includes an evaporator  10 , a condenser  20 , a pipeline  30  connecting the evaporator  10  with the condenser  20 , and two heat sinks  40  attached on two opposite sides of the condenser  20 . 
         [0012]    The evaporator  10  is a flat rectangular casing with a flat rectangular chamber (not shown) defined therein. A first wick structure (not shown) is provided lining an inner wall of the evaporator  10 . Working fluid (not shown), such as water or alcohol with low boiling point, is filled in the evaporator  10 . 
         [0013]    The condenser  20  is an elongated, flat, and rectangular casing with a flat rectangular chamber  28  defined therein. The condenser  20  includes a first cap  21  and a second cap  22 , connected with each other to form the condenser  20 . The first cap  21  and the second cap  22  are each provided with a second wick structure  23  lining an inner wall thereof. A plurality of supporting posts  24  is provided in the condenser  20 . The supporting posts  24  provide support between the first cap  21  and the second cap  22 , avoiding denting of the condenser  20 . The second wick structure  23  defines a plurality of through holes  230  receiving opposite ends of the supporting posts  24 . 
         [0014]    Referring also to  FIG. 3 , the pipeline  30  includes a tube  31  and a third wick structure  32  lining an inner wall of the tube  31 . The tube  31  communicates with the chamber of the evaporator  10  and with the chamber  28  of the condenser  20 . The pipeline  30  defines a vapor passage  321  therein along an axial direction thereof. The third wick structure  32  of the pipeline  30  connects the first wick structure of the evaporator  10  with the second wick structure  23  of the condenser  20 , and the vapor passage  321  of the pipeline  30  communicates with the chamber of the evaporator  10  and the chamber  28  of the condenser  20 . 
         [0015]    The first wick structure, the second wick structure  23  and the third wick structure  32  each can be sintered powder or a mesh screen of metal or organic woven fibers, etc. In this embodiment, the first wick structure, the second wick structure  23  and the third wick structure  32  are sintered powder. 
         [0016]    Each of the heat sinks  40  includes a base plate  41 , and a plurality of fins  42  extending perpendicularly from the base plate  41 . The base plate  41  has a contour mating with a corresponding part of the condenser  20 . The base plates  41  of the two heat sinks  40  are respectively attached on two opposite sides (i.e., top and bottom sides) of the condenser  20 . 
         [0017]    In manufacturing, air in the heat dissipation apparatus  100  is evacuated, creating a vacuum therein, such that the working liquid in the evaporator  10  is easily evaporated. During operation, the evaporator  10  of the heat dissipation apparatus  100  is attached to a heat source to absorb heat therefrom. The working fluid at the evaporator  10  absorbs the heat and vaporizes. The vapor moves, bearing the heat, towards the condenser  20  through the vapor passage  321  of the pipeline  30 , due to the different vapor pressure between the evaporator  10  and the condenser  20 . When the vapor reaches the condenser  20 , the vapor is condensed, thereby transferring the heat to the two heat sinks  40 . The heat sinks  40  release the heat into the ambient environment. Due to the different capillary pressure between the first wick structure and the second wick structure  23 , the condensate is then drawn back by the third and the second wick structures  32 ,  23  and the first wick structure to the evaporator  10 , where the condensate is again available for evaporation. 
         [0018]    In the heat dissipation apparatus  100 , the condenser  20  has a large heat transfer area, and a large inner space due to its flat rectangular chamber  28 . Thereby, the heat dissipation apparatus  100  provides not only a large contact area between the vapor and the condenser  20  but also reduced flow resistance of the vapor. The vapor in the condenser  20  is condensed quickly, avoiding drying out at the evaporator  10 . In addition, the condenser  20  does not need to be curved or staved. Therefore the second wick structure  23  in the condenser  20  avoids being destroyed during manufacturing of the condenser  20 . Furthermore, the working fluid is drawn back by the third wick structure  32 , the second wick structure  23  and the first wick structure, whereby any impeding influence of gravity acting on the working fluid is essentially eliminated. 
         [0019]      FIG. 4  shows an alternative embodiment of a heat dissipation apparatus  100   a . The heat dissipation apparatus  100   a  differs from that of the previous embodiment only in that a second pipeline  50  is also included. The second pipeline  50  connects the evaporator  10  with the condenser  20  to form a loop together with the pipeline  30 . The second pipeline  50  is a hollow tube communicating the chamber of the evaporator  10  with the chamber  28  of the condenser  20 . Thereby, the second pipeline  50  allows condensate in the condenser  20  to flow back to the evaporator  10 , and thus provides the heat dissipation apparatus  100   a  with a loop-based heat dissipation capability. 
         [0020]    It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, 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.