Abstract:
In one aspect, the present invention relates to a heat-dissipation system. The heat-dissipation system includes a heat sink having a plurality of fins coupled thereto and a heat pipe having an evaporator portion and a condenser portion. The heat pipe has a heat-transfer fluid disposed therein. The evaporator portion is disposed within the heat sink and the condenser portion is disposed externally to the heat sink. A fan is arranged to circulate air over the plurality of fins and the condenser portion. A heat-transfer coefficient of the heat-transfer fluid supplements a heat-transfer coefficient of air moving over the condenser portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to, and incorporates by reference for any purpose the entire disclosure of, U.S. Provisional Patent Application No. 61/942,141, filed Feb. 20, 2014. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present application relates generally to heat-dissipation systems and more particularly, but not by way of limitation, to heat-dissipation systems utilizing a heat pipe to maximize the heat-transfer capability of an extruded heat sink. 
         [0004]    2. History of the Related Art 
         [0005]    Many aspects of methods of and systems for cooling and heating utilizing heat pipes are well developed. A heat pipe is a device for transferring heat through cyclic evaporation and condensation of a liquid enclosed in a casing from which noncondensable gasses have been removed. There are, of course, significant limitations to the amount of heat a heat pipe can transfer in a given time or in a given space. 
         [0006]    The need for thermal stabilization of electronic components is well recognized. In that regard, low profile extrusion (“LPE”) cooling devices are extremely useful in printed circuit board (PCB) level cooling of electronic components, and for use as heat exchangers in applications where space is limited and/or low weight is critical. LPE refers to a heat exchange apparatus comprising an integral piece of metal having a series of micro-extruded hollow tubes formed therein for containing a fluid. LPE&#39;s preferably have multi-void micro-extruded tubes designed to operate under pressures and temperatures required by modern environmentally safe refrigeration gases and to resist corrosion. Aspects of LPE&#39;s and their related applications in the industry are set forth and shown in the above-referenced co-pending U.S. patent application Ser. No. 09/328,183 (now U.S. Pat. No. 6,935,409), which is incorporated herein by reference. 
         [0007]    Low profile extrusions can currently be manufactured with a profile, or height, as low as about 0.05 inches and with tubes of varying inner diameters. Of course, future advances may allow such low profile extrusions to be manufactured with an even smaller profile. Such low profile extrusions have been conventionally used in heat-exchanger applications in the automotive industry, and are commercially available in strip form (having a generally rectangular geometry) or coil form (a continuous strip coiled for efficient transport). 
       SUMMARY 
       [0008]    The present application relates generally to heat-dissipation systems and more particularly, but not by way of limitation, to heat-dissipation systems utilizing a heat pipe to maximize the heat-transfer capability of an extruded heat sink. In one aspect, the present invention relates to a heat-dissipation system. The heat-dissipation system includes a heat sink having a plurality of fins coupled thereto and a heat pipe having an evaporator portion and a condenser portion. The heat pipe has a heat-transfer fluid disposed therein. The evaporator portion is disposed within the heat sink and the condenser portion is disposed externally to the heat sink. A fan is arranged to circulate air over the plurality of fins and the condenser portion. A heat-transfer coefficient of the heat-transfer fluid supplements a heat-transfer coefficient of air moving over the condenser portion. 
         [0009]    In another aspect, the present invention relates to a method of increasing a heat-transfer capability of a heat sink. The method includes thermally exposing a heat sink to a heat-generating component. The heat sink includes a plurality of fins coupled thereto. The method further includes arranging a heat pipe through the heat sink. The heat pipe includes an evaporator portion disposed within the heat sink and a condenser portion disposed outwardly of the heat sink. The method further includes arranging a fan proximate the heat sink and the condenser portion and circulating air over the condenser portion and between adjacent ones of the plurality of fins. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawings in which: 
           [0011]      FIG. 1  is a cross-sectional view of a prior-art cooling system; 
           [0012]      FIG. 2  is a side view of a heat-dissipation system according to an exemplary embodiment; 
           [0013]      FIG. 3  is a cross-sectional view of the heat-dissipation system of  FIG. 2  according to an exemplary embodiment; 
           [0014]      FIG. 4  is a bottom perspective view of the heat-dissipation system of  FIG. 2  according to an exemplary embodiment; 
           [0015]      FIG. 5  is a top perspective view of the heat-dissipation system of  FIG. 2  according to an exemplary embodiment; 
           [0016]      FIG. 6  is an exploded view of the heat-dissipation system of  FIG. 2  according to an exemplary embodiment; 
           [0017]      FIG. 7  is a perspective view of a heat-dissipation system according to an exemplary embodiment; 
           [0018]      FIG. 8  is a perspective view of a heat-dissipation system according to an exemplary embodiment; 
           [0019]      FIG. 9A  is a front perspective view of a heat-sink assembly according to an exemplary embodiment; 
           [0020]      FIG. 9B  is a rear perspective view of a heat-sink assembly according to an exemplary embodiment; 
           [0021]      FIG. 10A  is a perspective view of a heat-dissipation system according to an exemplary embodiment; 
           [0022]      FIG. 10B  is a side view of a heat-dissipation system according to an exemplary embodiment; 
           [0023]      FIG. 10C  is a cross-sectional view of a heat-dissipation system according to an exemplary embodiment; 
           [0024]      FIG. 11A  is a perspective view of a heat-dissipation system according to an exemplary embodiment; 
           [0025]      FIG. 11B  is a side view of a heat-dissipation system according to an exemplary embodiment; and 
           [0026]      FIG. 11C  is a cross-sectional view of a heat-dissipation system according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Various embodiments of the present invention will now be described more fully with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. 
         [0028]      FIG. 1  is a cross-sectional view of a prior-art cooling system  100 . A heat sink  102  is placed in thermal contact with a warm side of a thermo-electric chip  104 . The heat sink  102  includes a plurality of fins  106  to facilitate heat transfer. A fan  108  circulates air between the plurality of fins  106 . During operation, heat is generated by the warm side of the thermoelectric chip  104 . The heat is transferred to the plurality of fins  106  of the heat sink  102  where the heat is exhausted to an atmosphere by air that is circulated by the fan  108  between the plurality of fins  106 . In the arrangement shown in  FIG. 1 , the heat-transfer capacity of the cooling system  100  is limited by the thermal conductivity of the air that is circulated between the plurality of fins  106 . 
         [0029]      FIG. 2  is a side view of a heat-dissipation system  200 .  FIG. 3  is a cross-sectional view of the heat-dissipation system  200 . Referring now to  FIGS. 2-3 , the heat-dissipation system  200  includes a heat sink  202  with a heat pipe  204  disposed therethrough. The heat sink  202  abuts a warm side of a thermoelectric element  206 ; however, in other embodiments, the heat sink  202  could be arranged to abut any heat-generating component. A plurality of fins  208  extend from the heat sink  202  in a direction opposite the thermoelectric element  206 . The plurality of fins  208  are arranged generally parallel with respect to each other. 
         [0030]    Still referring to  FIGS. 2-3 , the heat pipe  204 , in a typical embodiment, is a low-profile extrusion having a plurality of micro tubes formed therein. The heat pipe  204  includes an evaporator portion  210  (shown in  FIG. 5 ) and a condenser portion  212 . The evaporator portion  210  is disposed within the heat sink  202  near an interface with the thermoelectric element  206 . The evaporator portion  212  is disposed outside of the heat sink  202  away from the interface with the thermoelectric element  206 . In a typical embodiment, the heat pipe  204  contains a heat-transfer fluid such as, for example, glycol, ammonia, and the like. 
         [0031]      FIG. 4  is a bottom perspective view of the heat-dissipation system  200 .  FIG. 5  is a top perspective view of the heat-dissipation system  200 .  FIG. 6  is a cross-sectional view of the heat-dissipation system  200 . Referring to  FIGS. 4-6 , the heat pipe  204  is generally U-shaped. A second plurality of fins  214  surround the condenser portion  212 . A fan  216  is disposed adjacent to the condenser portion  212 . In a typical embodiment, the fan  216  circulates air through the second plurality of fins  214 , the condenser portion  212  and the plurality of fins  208 . 
         [0032]    Referring to  FIGS. 2-6 , during operation, heat is generated by the warm side of the thermoelectric element  206 . The heat is transmitted to the heat sink  202  and the plurality of fins  208 . At the same time, the heat causes the heat-transfer fluid in the evaporator portion  210  to vaporize into a gaseous phase. Vaporization of the heat-transfer fluid consumes some of the heat generated by the thermoelectric element  206 . The gaseous phase travels from the evaporator portion  210  to the condenser portion  212  by way of capillary action facilitated by the plurality of micro tubes. The fan  216  circulates air through the second plurality of fins  214 , the condenser portion  212 , and the plurality of fins  208 . 
         [0033]    Still referring to  FIGS. 2-6 , air circulated by the fan  216  causes the gaseous heat-transfer fluid to condense to a liquid phase. Such a phase change facilitates exhaustion of heat to an external environment. In addition, heat transferred to the heat sink  202  and the plurality of fins  208  is exhausted by movement of air. As shown in  FIGS. 2-5 , the fan  216  is arranged adjacent to the condenser portion  212  and opposite the thermoelectric element  206 . The fan  216  moves air around the condenser portion  212  and into the plurality of fins  208 . The air then travels outwardly in a direction generally parallel to the plurality of fins  208 . The heat pipe  204  supplements the heat transfer capacity of the ambient air. The addition of the heat pipe  204  thereby allows the heat sink  202  to operate with increased capacity and efficiency than if the heat pipe  204  were not present. Additionally, the heat pipe  204  allows the heat sink  202  to be of a smaller size that if the heat pipe  204  were not present. 
         [0034]      FIG. 7  is a perspective view of a heat-dissipation system  700 . The heat-dissipation system  700  includes a heat sink  702  having a heat pipe  704  disposed there through. The heat sink  702  includes a plurality of fins  706 . The heat sink  702  abuts a warm side of a thermoelectric element  708 ; however, in other embodiments, the heat sink  702  could be arranged to abut any heat-generating component. A plurality of fins  710  extend from the heat sink  702  in a direction opposite the thermoelectric element  708 . The plurality of fins  710  are arranged generally parallel with respect to each other. 
         [0035]    Still referring to  FIG. 7 , the heat pipe  704 , in a typical embodiment, is a low-profile extrusion having a plurality of micro tubes formed therein. The heat pipe  704  includes an evaporator portion (not shown) and a condenser portion  714 . The evaporator portion is disposed within the heat sink  702  near an interface with the thermoelectric element  708 . The condenser portion  714  is disposed outside of the heat sink  702  away from the interface with the thermoelectric element  708 . In a typical embodiment, the heat pipe  704  contains a heat-transfer fluid such as, for example, glycol, ammonia, and the like. 
         [0036]    Still referring to  FIG. 7 , the heat pipe  704  is generally L-shaped. A second plurality of fins  716  surround the condenser portion  714 . A fan  718  is disposed adjacent to the plurality of fins  710 . In a typical embodiment, the fan  718  directs air downwardly into the plurality of fins  710 . The air then travels in a direction generally parallel to the plurality of fins  710  and across the condenser portion  714  and the second plurality of fins  716  facilitating exhaustion of heat therefrom. 
         [0037]      FIG. 8  is a perspective view of a heat-dissipation system  800 . The heat-dissipation system  800  includes a heat sink  802  having a heat pipe  804  disposed there through. The heat sink  802  includes a plurality of fins  806 . The heat sink  802  abuts a warm side of a thermoelectric element  808 ; however, in other embodiments, the heat sink  802  could be arranged to abut any heat-generating component. A plurality of fins  810  extend from the heat sink  802  in a direction opposite the thermoelectric element  808 . The plurality of fins  810  are arranged generally parallel with respect to each other. 
         [0038]    Still referring to  FIG. 8 , the heat pipe  804 , in a typical embodiment, is a low-profile extrusion having a plurality of micro tubes formed therein. The heat pipe  804  includes an evaporator portion and a condenser portion  814 . The evaporator portion is disposed within the heat sink  802  near an abutment with the thermoelectric element  808 . The condenser portion  814  is disposed outside of the heat sink  802  away from the interface with the thermoelectric element  808 . In a typical embodiment, the heat pipe  804  contains a heat-transfer fluid such as, for example, glycol, ammonia, and the like. 
         [0039]    Still referring to  FIG. 8 , the heat pipe  804  is generally L-shaped. A second plurality of fins  816  surround the condenser portion  814 . A fan  818  is disposed adjacent to the plurality of fins  810 . In a typical embodiment, the fan  818  directs air through the plurality of fins  810  and in a direction generally parallel to the plurality of fins  810 . The air then travels across the condenser portion  814  and the second plurality of fins  816  facilitating exhaustion of heat therefrom. 
         [0040]      FIG. 9A  is a front perspective view of a heat-sink assembly  900 .  FIG. 9B  is a rear perspective view of the heat dissipation system  900 . the heat-sink assembly  900  includes a heat sink  902  with a heat pipe  904  disposed therethrough. The heat sink  902  abuts, for example, a warm side of a thermoelectric element (shown in  FIG. 10 ); however, in other embodiments, the heat sink  902  could be arranged to abut any heat-generating component. A plurality of fins  908  extend from the heat sink  902  in a direction opposite, for example, a thermoelectric element. The plurality of fins  908  are arranged generally parallel with respect to each other. 
         [0041]    Still referring to  FIGS. 9A-9B , the heat pipe  904  is a low-profile extrusion having a plurality of micro tubes formed therein. By way of example, the heat pipe  904  could, in some embodiments, be a PhasePlane® heat pipe manufactured by ThermoTek, Inc. of Flower Mound, Tex. The heat pipe  904  includes an evaporator portion  910  and a condenser portion  912 . The evaporator portion  910  is disposed within the heat sink  902  near an interface with, for example, the thermoelectric element. The evaporator portion  912  is disposed outside of the heat sink  902  away from the interface with the thermoelectric element  906 . In a typical embodiment, the heat pipe  904  contains a heat-transfer fluid such as, for example, glycol, ammonia, and the like. 
         [0042]    Still referring to  FIGS. 9A-9B , the heat pipe  904  is generally U-shaped. A second plurality of fins  914  surround the condenser portion  912 . As shown in  FIG. 9B , a notch  905  is formed in the heat sink  902  to accommodate the heat pipe  904 . The notch  905  facilitates direct contact of the evaporator portion  910  of the heat pipe with, for example, a warm side of a thermoelectric element (shown in  FIG. 10 ). The flat profile of the heat pipe  904  increases contact area between the heat pipe  904  and, for example, the warm side of the thermoelectric element. Such increased contact area improves heat transfer between, for example the warm side of the thermoelectric element and the heat pipe  904 . In some embodiments, a fan (not shown) is disposed adjacent to the condenser portion  912 . In a typical embodiment, the fan circulates air through the second plurality of fins  914 , the condenser portion  912  and the plurality of fins  908 . In a typical embodiment, the heat sink  902  increases an operational thermal range of the heat pipe  904  beyond the thermal range of the heat pipe  904  if the heat sink  902  were not present. 
         [0043]      FIG. 10A  is a perspective view of a heat-dissipation system  1000 .  FIG. 10B  is a side view of the heat-dissipation system  1000 .  FIG. 10C  is a cross sectional view of the heat dissipation system  1000 . Referring to  FIGS. 10A-10C , the heat dissipation system  1000  includes the heat sink assembly  900  discussed above with reference to  FIGS. 9A-9B . As shown in  FIGS. 10A-10C , the heat-sink assembly  900  is arranged such that the heat pipes  902  are placed flat against the warm side  1004  of a thermoelectric element  1002 . The notch  905  facilitates direct contact of the evaporator portion  910  of the heat pipe  904  with a warm side  1004  of a thermoelectric element  1002 . The flat profile of the heat pipe  904  increases contact area between the heat pipe  904  and the warm side  1004  of the thermoelectric element  1002 . Such increased contact area improves heat transfer between the warm side of the thermoelectric element  1002  and the heat pipe  904 . As shown in  FIGS. 10A-10C , the cool side  1006  of the thermoelectric element  1002  is placed in thermal contact with a manifold  1008  having a heat-transfer fluid circulating therethrough. In a typical embodiment, the manifold  1008  has a plurality of channels disposed therethough. In a typical embodiment, the plurality of channels include surface enhancements to facilitate optimal heat transfer. Such an arrangement facilitates optimization of both the warm side  1004  and the cool side  1006  of the thermoelectric element  1002 . 
         [0044]      FIG. 11A  is a perspective view of a heat-dissipation system  1100 .  FIG. 11B  is a side view of the heat-dissipation system  1100 .  FIG. 11C  is a cross sectional view of the heat dissipation system  1100 . Referring to  FIGS. 11A-11C , the heat dissipation system  1100  includes the heat sink assembly  900  discussed above with reference to  FIGS. 9A-9B . As shown in  FIGS. 11A-11C , the heat-sink assembly  900  is arranged such that the heat pipes  902  are placed flat against the warm side  1104  of a thermoelectric element  1102 . The notch  905  facilitates direct contact of the evaporator portion  910  of the heat pipe  904  with a warm side  1104  of a thermoelectric element  1102 . The flat profile of the heat pipe  904  increases contact area between the heat pipe  904  and the warm side  1104  of the thermoelectric element  1102 . Such increased contact area improves heat transfer between the warm side of the thermoelectric element  1102  and the heat pipe  904 . 
         [0045]    Still referring to  FIGS. 11A-11C , the heat dissipation system  1100  includes a heat sink assembly  900 ′, which assembly is similar in construction to the heat sink assembly  900  discussed above with reference to  FIGS. 9A-9B . As shown in  FIGS. 11A-11C , the heat-sink assembly  900 ′ is arranged such that the heat pipes  902 ′ are placed flat against the warm side  1104 ′ of a thermoelectric element  1102 ′. The notch  905 ′ facilitates direct contact of the evaporator portion  910 ′ of the heat pipe  904 ′ with a warm side  1104 ′ of a thermoelectric element  1102 ′. The flat profile of the heat pipe  904 ′ increases contact area between the heat pipe  904 ′ and the warm side  1104 ′ of the thermoelectric element  1102 ′. Such increased contact area improves heat transfer between the warm side of the thermoelectric element  1102 ′ and the heat pipe  904 ′. As shown in  FIGS. 11A-11C , the cool side  1106  of the thermoelectric element  1102  and the cool side  1106 ′ of the thermoelectric element  1102  are placed in thermal contact with a manifold  1108  having a heat-transfer fluid circulating therethrough. In a typical embodiment, the manifold  1108  has a plurality of channels disposed therethough. In a typical embodiment, the plurality of channels include surface enhancements to facilitate optimal heat transfer. Such an arrangement facilitates optimization of both the warm side  1104  and the cool side  1106  of the thermoelectric element  1102  and the warm side warm side  1104 ′ and the cool side  1106 ′ of the thermoelectric element  1102 ′. 
         [0046]    The advantages of the present invention will be apparent to those skilled in the art. As described herein, the heat pipe ( 204 ,  704 ,  804 ) supplements the heat transfer capacity of the ambient air. The addition of the heat pipe ( 204 ,  704 ,  804 ) thereby allows the heat sink ( 202 ,  702 ,  802 ) to operate with increased capacity and efficiency than if the heat pipe ( 204 ,  704 ,  804 ) were not present. Additionally, the heat pipe ( 204 ,  704 ,  804 ) allows the heat sink ( 202 ,  702 ,  802 ) to be of a smaller size that if the heat pipe ( 204 ,  704 ,  804 ) were not present. In a typical embodiment, the heat sink ( 202 ,  702 ,  802 ,  902 ) increases an operational thermal range of the heat pipe ( 204 ,  704 ,  804 ,  904 ) beyond the thermal range of the heat pipe ( 204 ,  704 ,  804 ,  904 ) if the heat sink ( 202 ,  702 ,  802 ,  902 ) were not present. 
         [0047]    Although various embodiments of the method and system of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Specification, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit and scope of the invention as set forth herein. It is intended that the Specification and examples be considered as illustrative only.