Abstract:
A heat dissipating system includes: a heat-absorbing unit having at least one cavity body adapted to contact a heat source, and a working fluid received in the cavity body; a condenser to condense the working fluid; and a tubing unit connected fluidly to the condenser and the heat-absorbing unit. The working fluid flows through the tubing unit to circulate from the condenser to the heat-absorbing unit by gravity and from the heat-absorbing unit to the condenser by natural convection. The tubing unit forms a closed circulating loop with the heat-absorbing unit and the condenser.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority of Taiwanese Application No. 095136005, filed on Sep. 28, 2006. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to heat dissipation, more particularly to a heat dissipating system and method. 
         [0004]    2. Description of the Related Art 
         [0005]    Referring to  FIG. 1 , a liquid-cooling heat dissipating system, as disclosed in Taiwanese Publication No. M295424, includes a heat sink  11  for exchanging heat with external cold air by convection, a thermoelectric cooler  12 , a pressure-increasing pump  13  to circulate a working fluid within the system, a liquid-cooling connector  14  in contact with a heat source  2 , three input pipes  15  for interconnecting the heat sink  11 , the thermoelectric cooler  12 , the pump  13 , and the liquid-cooling connector  14  in series, an output pipe  16  connected fluidly to the heat sink  11  and the liquid-cooling connector  14 , and a fan  17  for directing a current of cold air toward the heat sink  11 . The heat source  2  may be a central processing unit of a computer. 
         [0006]    When the pressure-increasing pump  13  is activated, the working fluid in the liquid-cooling connector  14  circulates toward the heat sink  11  after absorbing the heat generated by the heat source  2 . The heat sink  11  then exchanges heat with the external current of cold air so as to dissipate the heat. Although the aforementioned heat dissipating system can achieve its intended purpose, in actual practice, it has the following drawbacks: 
         [0007]    1. Since the aforementioned liquid-cooling heat dissipating system relies on the pressure-increasing pump  13  to circulate the working fluid, the system not only has more components, is more costly, and is more noisy, but also generates more heat itself due to the pressure-increasing pump  13 . This runs counter to efforts at reducing the temperature of the working fluid in the system and, therefore, reduces the cooling efficiency of the system. 
         [0008]    2. If the aforementioned working fluid is water, the water will freeze when the system is used in a cold area with a temperature lower than 0° C., thereby rendering the system useless. Further, if there is water leakage in the system, circuitry in the heat source  2  and/or elements of the system itself may be destroyed. 
       SUMMARY OF THE INVENTION 
       [0009]    Therefore, the object of the present invention is to provide a heat dissipating system that can reduce noise to a minimum and that can effectively enhance heat dissipation. The present invention also provides a method for dissipating heat from a heat source. According to one aspect of this invention, a heat dissipating system comprises: a heat-absorbing unit having at least one cavity body adapted to contact a heat source, and a working fluid received in the cavity body; a condenser to condense the working fluid; and a tubing unit connected fluidly to the condenser and the heat-absorbing unit. The working fluid flows through the tubing unit to circulate from the condenser to the heat-absorbing unit by gravity and from the heat-absorbing unit to the condenser by natural convection. The tubing unit forms a closed circulating loop with the heat-absorbing unit and the condenser. 
         [0010]    According to another aspect of this invention, a computer module comprises a housing, at least one chip disposed in the housing, a heat-absorbing unit, a condenser, and a tubing unit. The heat-absorbing unit has at least one cavity body contacting the chip, and a working fluid received in the cavity body. The condenser is disposed in the housing to condense the working fluid. The tubing unit is connected fluidly to the condenser and the heat-absorbing unit. The working fluid flows through the tubing unit to circulate from the condenser to the heat-absorbing unit by gravity and from the heat-absorbing unit to the condenser by natural convection. The tubing unit forms a closed circulating loop with the heat-absorbing unit and the condenser. According to still another aspect of this invention, a method for dissipating heat from a heat source comprises the steps of: (a) contacting the heat source with a heat-absorbing cavity body to cause a working fluid contained in the cavity body to vaporize; (b) allowing the vaporized working fluid to flow upward and enter a condenser by natural convection; (c) condensing the vaporized working fluid in the condenser; (d) cooling the condensed working fluid using a thermoelectric cooler and a heat sink; and (e) allowing the condensed working fluid to flow downward and back into the cavity body by gravity. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which: 
           [0012]      FIG. 1  is a perspective view of a conventional liquid-cooling heat dissipating system disclosed in Taiwanese Publication No. M295424; 
           [0013]      FIG. 2  is a perspective view of the first preferred embodiment of a heat dissipating system and method according to the present invention; 
           [0014]      FIG. 3  is a fragmentary sectional view of a condenser of the first preferred embodiment; 
           [0015]      FIG. 4  illustrates the first preferred embodiment installed in a computer module; 
           [0016]      FIG. 5  is a schematic side view of  FIG. 4 ; 
           [0017]      FIG. 6  is a flow chart illustrating the steps involved during operation of the heat dissipating system of the present invention; 
           [0018]      FIG. 7  is a schematic view of the second preferred embodiment of a heat dissipating system and method according to the present invention; and 
           [0019]      FIG. 8  is a schematic view of the third preferred embodiment of a heat dissipating system and method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Before the present invention is described in greater detail, it should be noted that the same reference numerals have been used to denote like elements throughout the specification. 
         [0021]    Referring to  FIGS. 2 to 5 , the first preferred embodiment of a heat dissipating system according to the present invention is installed in a computer module  3 . The computer module  3  has a housing  33  defining upper and lower chambers  31 ,  32 , a mounting board  34  fixed inside the lower chamber  32 , and a plurality of module chips  35  mounted on the mounting board  34 . The heat dissipating system of the present invention comprises a condenser  4 , a heat-absorbing unit  5 , and a tubing unit  6 . The module chips  35  are heat sources to undergo heat dissipation by the system of the present invention. The condenser  4  is disposed in the upper chamber  31  of the computer module  3 , and includes a vapor-receiving part  411  formed on a top end thereof, an inlet  414  connected fluidly to the vapor-receiving part  411 , a liquid-receiving part  412  formed on a bottom end thereof, an outlet  415  connected fluidly to the liquid-receiving part  412 , a plurality of channels  413  connected between the vapor-receiving and liquid-receiving parts  411 ,  412 , and a thermoelectric cooler  42 . The thermoelectric cooler  42  is controlled through a circuit, and has a cold side  421  in contact with the liquid-receiving part  412 , and a hot side  422  opposite to the cold side  421 . The cold side  421  has a cooling function so as to keep the liquid-receiving part  412  at a constant temperature. The heat dissipating system of the present invention further comprises a heat sink  43  and a fan  44 . The heat sink  43  is disposed adjacent to the condenser  4 , and has an L-shaped configuration. The heat sink  43  includes a horizontal plate  431  having a contact portion  4311  in contact with the hot side  422  of the thermoelectric cooler  42 , a vertical plate  432  extending upwardly from an end periphery of the horizontal plate  431  and parallel to the condenser  4 , and a plurality of fins  433  provided on the vertical plate  432 . The fan  44  is disposed proximate to the condenser  4  and the heat sink  43 , and directs a current of cold air toward the condenser  4  and the heat sink  43 , as best shown in  FIG. 5 . 
         [0022]    The heat-absorbing unit  5 , in this embodiment, includes first, second, and third cavity bodies  51 ,  52 ,  53  respectively in contact with the chips  35  of the computer module  3 . Each of the first to third cavity bodies  51 ,  52 ,  53  has an inlet  511 ,  521 ,  531 , and an outlet  512 ,  522 ,  532 . The inlet  414  and the outlet  415  of the condenser  4  are disposed at a level higher than those of the first to third cavity bodies  51 ,  52 ,  53 . 
         [0023]    The tubing unit  6 , in this embodiment, includes first, second, third, and fourth tubes  61 ,  62 ,  63 ,  64 . The first tube  61  is connected to the outlet  415  of the condenser  4  and to the inlet  511  of the first cavity body  51 . The second tube  62  is connected to the outlet  512  of the first cavity body  51  and to the inlet  521  of the second cavity body  52 . The third tube  63  is connected to the outlet  522  of the second cavity body  52  and to the inlet  531  of the third cavity body  53 . The fourth tube  64  is connected to the outlet  532  of the third cavity body  53  and to the inlet  414  of the condenser  4 . As such, the first to fourth tubes  61 ,  62 ,  63 ,  64 , the condenser  4 , and the first to third cavity bodies  51 ,  52 ,  53  form a closed circulating loop, as best shown in  FIG. 4 . 
         [0024]    A working fluid  30  is injected into the system of the present invention after the first to fourth tubes  61 ,  62 ,  63 ,  64 , the first to third cavity bodies  51 ,  52 ,  53 , and the condenser  4  are evacuated, so that the working fluid  30  circulates in a vacuum environment. In this embodiment, the working fluid  30  is a coolant that is in a liquid state at room temperature. Alternatively, the working fluid  30  may be a super-thermal-conductive liquid. 
         [0025]    Referring to  FIG. 6 , the steps involved in the method for dissipating heat from the chips  35  are shown. 
         [0026]    In step  71 , the first, second, and third cavity bodies  51 ,  52 ,  53  are placed in contact with the respective chips  35 , which have the lowest, medium, and highest temperatures, respectively. Initially, the working fluid  30  is in a liquid state and is in the first and second cavity bodies  51 ,  52 . After the computer module  3  is switched on, the liquid-state working fluid  30  in the first and second cavity bodies  51 ,  52  is vaporized. As the pressure inside the first cavity body  51  increases, the working fluid  30  in a vaporized state flows into the second cavity body  52  through the second tube  62 . As the pressure inside the second cavity body  52  also increases, the liquid-state working fluid  30  in the second cavity body  52  is pressurized and is caused to flow through the third tube  63  and into the third cavity body  53  where the temperature is the highest. The liquid-state working fluid  30  is vaporized in the third cavity body  53 . 
         [0027]    The number of tubes of the tubing unit  6  can be set according to the number of the module chips  35 . As such, the working fluid  30  can flow successively from the lowest- to the highest-temperature module chips  35  through the cavity bodies  51 ,  52 ,  53 . 
         [0028]    In step  72 , the vaporized working fluid  30  flows upward by natural convection through the fourth tube  64  from a high-density region, which is the third cavity body  53 , into a low-density region, which is the vapor-receiving part  411  of the condenser  4 . 
         [0029]    In step  73 , the fan  44  blows cold air toward the condenser  4  and the heat sink  43  so that the condenser  4  and the heat sink  43  exchange heat with the cold air. The vaporized working fluid  30  from the fourth tube  64  is condensed in the condenser  4 , and flows downward through the channels  413  by gravity into the liquid-receiving part  412 . 
         [0030]    In step  74 , through the cooling function of the cold side  421  of the thermoelectric cooler  42 , the temperature of the working fluid  30  in a condensed state and in the liquid-receiving part  412  continues to drop to a preset value, and the hot side  422  of the thermoelectric cooler  42  transfers the heat from the condensed working fluid  30  to the heat sink  43 , which dissipates the heat. 
         [0031]    In step  75 , the cooled condensed working fluid  30  in the liquid-receiving part  412  then flows back into the first cavity body  51  through the first tube  61  by gravity so as to repeat the aforementioned steps. Hence, by circulating the working fluid  30  through the condenser  4 , the first to third cavity bodies  51 ,  52 ,  53 , and the first to fourth tubes  61 - 64 , heat is effectively dissipated. 
         [0032]    Referring to  FIG. 7 , the heat dissipating system and method according to the second preferred embodiment of the present invention is shown to be similar to the first preferred embodiment. However, in this embodiment, the tubing unit  6  includes spaced-apart first and second manifolds  65 ,  67 , three spaced-apart first tubes  66  each connected between the first manifold  65  and the inlet  511 ,  521 ,  531  of the respective cavity body  51 ,  52 ,  53  so as to direct the liquid-state working fluid  30  into the respective cavity body  51 ,  52 ,  53 , three spaced-apart second tubes  68  each connected between the second manifold  67  and the outlet  512 ,  522 ,  532  of the respective cavity body  51 ,  52 ,  53  so as to direct the vaporized working fluid  30  into the second manifold  67 , a third tube  69  connected between the first manifold  65  and the liquid-receiving part  412  (see  FIG. 2 ) of the condenser  4 , and a fourth tube ( 69 ′) connected between the second manifold  67  and the vapor-receiving part  411  of the condenser  4 . 
         [0033]    The condensed working fluid  30  in the liquid-receiving part  412  of the condenser  4  flows down first into the first manifold  65  by gravity, and enters simultaneously the first to third cavity bodies  51 ,  52 ,  53  through the first tubes  66 . The vaporized working fluid  30  in the first to third cavity bodies  51 ,  52 ,  53  is collected at the second manifold  67 , and from the second manifold  67 , the vaporized working fluid  30  flows through the fourth tube  69 ′ and into the vapor-receiving part  411  of the condenser  4 . The working fluid  30  can self-circulate through the condenser  4 , the first to third cavity bodies  51 ,  52 ,  53 , and the first to fourth tubes  66 ,  68 ,  69 ,  69 ′, thereby effectively dissipating the heat in the system. 
         [0034]    Referring to  FIG. 8 , the heat dissipating system and method according to the third preferred embodiment of the present invention is shown to be similar to the second preferred embodiment. However, in this embodiment, the heat-absorbing unit  5  includes five cavity bodies  54  connected in parallel to each other using the first and second manifolds  65 ,  67  of the tubing unit  6 . Each cavity body  54  is in contact with an electronic component  7  that can generate heat. The arrangement of the tubing unit  6  is as illustrated in  FIG. 8 . 
         [0035]    The heat dissipating system and method of the present invention may also be applicable to dissipating heat of an engine or a machine of a car, or any other article that needs heat dissipation. 
         [0036]    From the aforementioned description, the advantages of the heat dissipating system and method of the present invention may be summarized as follows: 
         [0037]    1. Through phase change of the working fluid  30  from liquid to vapor and vapor to liquid, the working fluid  30  can undergo a self-circulating effect. Hence, compared to the conventional heat dissipating system that utilizes the pressure-increasing pump  13  (see  FIG. 1 ), the system of the present invention not only utilizes simple components, and reduces cost and noise to a minimum, but also minimizes self-generated heat. 
         [0038]    2. The working fluid  30  of the present invention, while in a liquid state, can effectively absorb heat from the module chips  35  through heat conduction, and is then vaporized so as to exchange heat with the condenser  4 . As such, not only can a heat dissipating effect and efficiency be enhanced, the present invention can also cooperate with the thermoelectric cooler  42  to control the temperature through an electric-controlled process, so that the condensed working fluid  30  can be maintained in a particular temperature range for any length of time, thereby ensuring a favorable heat dissipation effect. 
         [0039]    3. The working fluid  30  of the present invention makes use of a coolant or a super-thermal-conductive liquid, so that no freezing of the working fluid  30  is likely to occur when the working fluid  30  is used at a temperature below 0° C. Hence, the heat dissipation process can be carried out smoothly. Further, even if there is a leak in the system, the working fluid  30  will turn immediately into vapor so as not to damage electronic circuitry and/or elements of the heat dissipating system. 
         [0040]    While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.