LOOP HEAT PIPE MODULARIZED HEAT EXCHANGER

[0001] 1. Field of the Invention

[0002] The present invention relates to a heat exchanger system, particularly to a loop heat pipe modularized heat exchanger system.

[0003] 2. Description of Related Art

[0004] A conventional CPU-mounted heat exchanger, as shown in FIG. 1, comprises an attach block 10, a heat pipe 11, a heat exchanging unit 12, and a fan 13. The attach block 10 is mounted on a CPU 20. The heat pipe 11 connects with the attach block 10 and the heat exchanging unit 12 respectively. The fan 13 is disposed by the heat exchanging unit 12 to supply air for dissipating heat from the heat exchanging unit. As shown in FIG. 2, the heat pipe 11 is filled with a wick layer 111 so that fluid which evaporates easily flows inside the heat pipe 11 along the wick layer 111. The heat pipe 11 has a heated end connected to the attach block 10 and a cooled end connected to a lower side of the heat exchanging unit 12. The attach block 10 conducts heat generated by the CPU 20 and cause fluid in the heat pipe 11 to evaporate as vapor so that the vapor can absorb the heat and cool the CPU 20. At the cooled end of the heat pipe 11, the vapor condensates and returns to the heated end 112 to be heated and evaporated again, performing a heat-exchange cycle. Liquid and vapor in the heat pipe 11 flow counter to each other in a single pipe and pressure loss is large. If the heat pipe 11 is long, the efficiency of heat exchange is worse. There is no way tightly to engage the cooling end to a base or fins of the heat exchange unit 12 so that it results in a relatively large thermal resistance. The contact area between the heated end and the attach block is limited and it is not possible to eliminate a generated clearance between the heated end and the attach block so that the efficiency of heat transfer is low. If the attach block 10 is thicker, it will result in a larger thermal resistance to affect the efficiency of heat dissipation. Conventional heat exchangers not only have the shortcomings mentioned above but are also expensive to manufacture due to a large number of single components.

[0005] It is the main object of the present invention to provide a loop heat pipe modularized heat exchanger system with good efficiency of heat transfer.

[0006] Another object of the present invention is to provide a loop heat pipe modularized heat exchanger system with less component parts and easy assembly and manufacture.

[0007] The present invention can be more fully understood by reference to the following description and accompanying drawings, in which:

[0008] FIG. 1 is a perspective view of a conventional heat exchanger.

[0009] FIG. 2 is a schematic illustration of a conventional heat pipe;

[0010] FIG. 3 is a perspective view of a heat exchanger according to the present invention during use;

[0011] FIG. 4 is a perspective view of a base plate of the present invention in a first embodiment;

[0012] FIG. 5 is a perspective view of an external plate of the present invention in the first embodiment;

[0013] FIG. 6 is a sectional view illustrating the plates shown in FIGS. 4 and 5 after being assembled;

[0014] FIG. 7 is a sectional view illustrating the base plate shown in FIG. 4 and a flat plate being in a state of being assembled;

[0015] FIG. 8 is a top view of a base plate of the present invention in the second embodiment thereof;

[0016] FIG. 9 is a top view of a base plate of the present invention in the third embodiment thereof;

[0017] FIG. 10 is a top view of a base plate of the present invention in the fourth embodiment thereof;

[0018] FIG. 11 is a side view of the base plate shown in FIG. 10;

[0019] FIG. 12 is a top view of the base plates of the present invention in the fifth embodiment;

[0020] FIG. 13 is a sectional view of the base plate shown in FIG. 12;

[0021] FIG. 14 is a top view of the base plate of the present invention in the sixth embodiment thereof;

[0022] FIG. 15 is a top view of the external plate of the present invention in the sixth embodiment;

[0023] FIG. 16 is a sectional view of an external plate shown in FIG. 15; and

[0024] FIG. 17 is a perspective view illustrating a heat exchanger of the present invention in the sixth embodiment during use.

[0025] As shown in FIG. 3, a heat exchanger 30 of the present invention comprises a heat exchange unit 40 and a vapor chamber 50 connected thereto. As shown in FIG. 4, the heat exchange unit 40 further comprises a plurality of metal base plates 10 worked by a press or rolled by a cutter. Each of the base plates 10 at two ends thereof has a first projection 11 and a second projection 12, respectively, and at a middle part thereof having a plurality of depressions 13 and projections 14 alternately disposed side by side. The first and second projections 11, 12 have regularly arranged inward extending projecting sections 111, 121, and the projections 14 each have regularly arranged projecting sections 141, 142 extending to opposite sides. An elongated ridge 131 is placed in each depression 13, both ends thereof having connecting tubes 132 that reach up to the level of the top surfaces of the projections 14. Similarly, a groove 143 is placed in each projection 14, both ends thereof having connecting tubes 144 that reach down to the level of the bottom surfaces of the depressions 13. The connecting tubes 132 have through holes 133 at upper ends thereof, and the connecting tubes 144 have through holes 145 at lower ends thereof so that the ridges 131 and the grooves 143 have shapes corresponding to each other.

[0026] Referring to FIGS. 4 and 5, an external plate 20 of the present invention closes the through holes 133 and the grooves 143 from above. The external plate 20 is shaped like the base plates 10, but connecting tubes 211 at the upper ends thereof and the connecting tubes 221 at the lower ends thereof provide no through hole.

[0027] Referring to FIG. 6, several base plates 10 and an external plate 20 are disposed in a way of touching each other oppositely and joined together by brazing. Once the plates are fixedly attached to each other after brazing, pairs of ridges 21, 131, areas between two ridges 131 and areas between grooves 143 form horizontal tubes 15 respectively. Ridges 21, 131 and connecting tubes 132 constitute longitudinal series connection to form vertical tubes 16. Similarly, grooves 143 and connecting tubes 144 also constitute longitudinal series connection to form vertical tubes 16. Air holes 17 are disposed between adjacent horizontal tubes 15. It can be seen in FIG. 4 that the air holes 17 are formed at respective clearance between each projection and each ridge 131 and respective clearance between each depression and each groove 143. Due to design of the projecting sections 111, 121, 141, 142, turbulent effect can be enhanced while air passes through the air tubes 17 and a greater area of the base plates 10 can be contacted by air so that efficiency of heat exchange is promoted.

[0028] Referring to FIG. 7, alternatively a flat plate 23 replaces the external plate 20 shown in FIG. 6 to close the through holes 133 and the depressions 143 so that the same heat exchange effect as the plate assembly shown in FIG. 6 is attained.

[0029] Referring to FIG. 7 in company with FIG. 3, the vapor chamber 50 has a hollow space 51 attached with a wick layer 52 and an upper end thereof provides holes 53 corresponding to the through holes in the connecting tubes of the ridges 131 on the lowermost base plate 10 and corresponding to the grooves 143 so that the hollow space 51 is able to communicate with vertical tubes 41 of the heat exchange unit 40. The vapor chamber 50 is filled with easily evaporated liquid and the liquid flows along the wick layer 52. The hollow space 51 further houses a liquid tank 54 and a primary evaporation space 55. The liquid tank 54 stores and pre-heats the liquid and the liquid tank 54 and the evaporation space 55 at upper side thereof are connected to the vertical tubes 41 of the heat exchange unit 40 respectively so that a circuit is formed.

[0030] Once the present invention is in use, the metal vapor chamber 50 is placed on a heat source such as a CPU and heat dissipation paste is coated on the contact surface of the vapor chamber 50 and the CPU such that the primary evaporation space 55 can be adhered to the CPU. After the liquid in the hollow space 51 having been heated, the liquid is vaporized and rises to pass through the most of the holes 53 and enter the heat exchange unit 40. Further, the vapor rises in the vertical tubes 41 thereof and moves along the horizontal tubes 42 from the right to the left. During the vapor flowing in the tubes, the vapor contacts the lower temperature tube wall and condenses as liquid. The vapor further flows toward the right side of the figure along the horizontal tubes 42 and falls down along the vertical tubes 41 to the liquid tank 54 of the vapor chamber 50 via the holes 53. Then, the liquid passes through the wick layer 52 and arrives the evaporation space 55 to be heated and vaporized again such that heat exchange cycle can be repeated over and over. The cold air 60 or other fluid utilized in the present invention is blown to the right toward the heat exchange unit 40 from the left as shown in FIG. 3. Further, the cold air 60 enters the heat exchange unit 40 via air holes at both lateral sides of the horizontal tubes 42 to perform heat exchange. Since flow direction of the cold air is reversed to that of the liquid in the horizontal tubes 42, a counter flow arrangement is formed so that a best efficiency of heat exchange can be obtained. The liquid tank 54 and the primary evaporation space 55 at the bottom thereof can be paved with a wick layer 52. Also, the hollow chamber 51 at the lateral side and the upper side thereof can be optionally paved with another wick layer 52.

[0031] The present invention combines a conventional attach block and heat guide pipes as a single base and the heat guide pipes and tubes in the heat exchange unit can be designed as a single circuit. In this way, not only thermal resistance resulting from a conventional attach block is eliminated but also thermal resistance resulting from the attach block, the heat guide pipes and the heat exchange unit being insufficiently tight fit is eliminated. Further, pressure losses resulting from flow of the vapor being reversed to the liquid in heat guide pipes can be eliminated and the efficiency of heat exchange can be promoted greatly. Furthermore, the modular design of the present invention is advantageous for the automatic assembly and manufacture so that it is capable of saving the manufacturing cost greatly.

[0032] Referring to FIG. 8 in company with FIG. 4, a second embodiment of the present invention provides a further base plate 80 in which oval-shaped connecting tubes 801, 802, has replaced the circular connecting tubes 132, 144 shown in the first embodiment. Because the oval shaped cross section has a larger area than the circular cross section, the connecting tubes on two adjacent levers can be joined more easily and firmly.

[0033] Referring to FIG. 9 in company with FIG. 8, a third embodiment of the present invention has base plates 81. Each of the base plates 81 provides with additional circular connecting tubes 811 with or without through holes on each ridge thereof instead of the ridge 803 on the base plates 80 shown in FIG. 8. Furthermore, each groove on the base plate 81 has additional circular connecting tubes 812 with or without through holes instead of the groove 804 shown in FIG. 6. Thus, the connecting tubes 811, 812 make two adjacent base plates 81 be assembled more easily and firmly.

[0034] As shown in FIGS. 10 and 11 in company with FIG. 8, a fourth embodiment of the present invention has base plates 82 and each of the base plates 82 is provided with reinforcing ribs 821 under each of the projecting sections.

[0035] As shown in FIGS. 12 and 13 in company with FIG. 8, a fifth embodiment of the present invention provides a further base plate 83 in which ridges 831 are arranged to replace the grooves 804 and projection sections 805 shown in FIG. 8 and projecting sections 806, 807, 808, 809 shown in FIG. 8 are replaced with reinforcing ribs 832, 833, 834, 835, respectively.

[0036] As shown in FIG. 14 in company with FIG. 8, a sixth embodiment of the present invention provides a further base plate 71 which is similar to the base plate 80 shown in FIG. 8 except connecting tubes 713, 714 being placed at one ends of each ridge 711 and each groove 712 respectively and projecting sections 715, 716 being placed at the other ends of each ridge 711 and each groove 712 respectively.

[0037] Referring to FIGS. 15 and 16 in company with FIG. 14, a seventh embodiment of the present invention provides a further external plate 72 which is a flat plate with grooves 721 and projecting sections 722 corresponding to the grooves 712 and the projecting sections 716 of the base plates 71. The external plate 72 can be joined to a side of the base plate 71 in a way of the grooves 721 in the external plate 72 closing the grooves 712 in the base plate 71. Alternatively, the external plate 72 is a flat plate without grooves 721 to cover the grooves 712 in the base plate 71 only.

[0038] Referring to FIG. 17 in company with FIGS. 14 and 15, an eighth embodiment of the present invention provides another heat exchange unit 70, which is composed of multiple base plates 71 being disposed to oppositely overlap each other. Two opposite sides of the base plates 71 are connected to an external plate 72 respectively. The base plates 71 and the external plates 72 at the joining sections 715, 716, 722 thereof are disposed over and connected to a vapor chamber 90. Ridges 711 and grooves 712 of the base plate 71 are formed as vertical tubes 73 and the connecting tubes 713 and the ridges 711 as well as connecting tubes 714 and the grooves 712 are form horizontal tubes 74 respectively. The vapor chamber 90 has a hollow space 91 with two lateral sides thereof having a liquid tank 911 and a primary evaporation space 912. Liquid in the hollow space 91 is heated up and forms vapor to rise along the vertical tubes 73 via the primary evaporation 912. Further, the vapor flows along the horizontal tubes 74 toward two lateral sides thereof and moves downward along vertical tubes 73 at the lateral sides. The condensed liquid flows back to the wick layer 92 in the vapor chamber 90 for being heated up and vaporized again. In this way, the heat exchange cycle can be repeated over and over.

[0039] While the invention has been described with reference to preferred embodiments thereof, it is to be understood that modifications or variations may be easily made without departing from the spirit of this invention which is defined by the appended claims.