Patent Publication Number: US-10782079-B2

Title: Three-dimensional pulsating heat pipe, three-dimensional pulsating heat pipe assembly and heat dissipation module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 107132491 filed in in Taiwan, R.O.C. on Sep. 14, 2018, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     This disclosure relates to a pulsating heat pipe. 
     2. Related Art 
     A conventional pulsating heat pipe (PHP) is consisted of several straight and bent pipes, and it can be divided into the condenser, evaporator and adiabatic sections. 
     The pulsating heat pipe is a capillary tube. Due to the capillary dimension of the PHP, a train of liquid slugs and vapor bubbles having menisci on their edges is formed because of surface tension. When the evaporator section receives heat to heat up the vapor bubbles therein, the pressure difference between the evaporator section and condenser section occurs. This pressure difference pushes the liquid slugs toward the condenser section where both vapor bubbles and liquid slugs are cooled down. The pressure difference, caused by random distribution and various sizes of the vapor bubbles and the liquid slugs, drives the working fluid to oscillate intensively in the pipes, thereby achieving high thermal transmission efficiency. 
     SUMMARY 
     One embodiment of the disclosure provides a three-dimensional pulsating heat pipe. The three-dimensional pulsating heat pipe includes a pipe member and a connecting member. The pipe member is coiled around an axis to form a plurality of loop portions, and the loop portions are arranged in order along the axis so as to form a three-dimensional coiled structure. The three-dimensional coiled structure has a heat receiving section, and the pipe member has different effective pipe cross-sectional areas on two opposite sides adjacent to the heat receiving section. The connecting member is connected to two ends of the pipe member, such that the connecting member and the pipe member together form a closed loop. 
     One embodiment of the disclosure provides a three-dimensional pulsating heat pipe assembly. The three-dimensional pulsating heat pipe assembly includes two of the aforementioned three-dimensional pulsating heat pipes. The three-dimensional coiled structure of one of the three-dimensional pulsating heat pipes forms a storage space, and the other three-dimensional coiled structure is disposed in the storage space. 
     One embodiment of the disclosure provides a three-dimensional pulsating heat pipe assembly, which is adapted to be in thermal contact with two heat sources and a cold source. The three-dimensional pulsating heat pipe assembly includes two of the aforementioned three-dimensional pulsating heat pipes. Each of the three-dimensional coiled structure further has heat dissipation section, and the dissipation section and the heat receiving section are respectively located at two opposite sides of the three-dimensional coiled structure. Each of the three-dimensional coiled structures is in a L shape, and the three-dimensional coiled structures are disposed in a mirror-symmetrical manner. The heat receiving sections are located away from each other and configured to be respectively in thermal contact with the two heat sources, and the heat dissipation sections are located adjacent to each other and configured to be in thermal contact with the cold source. 
     One embodiment of the disclosure provides a heat dissipation module. The heat dissipation module includes a fin-and-tube heat exchanger, a plurality of fillings, a plurality of pipe members and a connecting member. The heat dissipation section includes a plurality of fins and a plurality of heat dissipation pipes, and the plurality of heat dissipation pipes are disposed through the plurality of fins. The plurality of fillings are disposed in the plurality of heat dissipation pipes. The plurality of pipe members each have a smaller pipe cross-sectional area than that of each of the plurality of heat dissipation pipes. The plurality of pipe members are connected to the plurality of heat dissipation pipes so as to form a continuous flow path including a plurality of loop portions that surround an axis. The plurality of loop portions are arranged in order along the axis so as to form a three-dimensional coiled structure. The three-dimensional coiled structure has a heat receiving section. The heat receiving section and the fin-and-tube heat exchanger are respectively located at two opposite sides of the three-dimensional coiled structure, and the pipe member has different effective pipe cross-sectional areas on two opposite sides adjacent to the heat receiving section. The connecting member is connected to two ends of the continuous flow path, such that the connecting member, the plurality of pipe members and the plurality of heat dissipation pipes together form a closed loop. 
     One embodiment of the disclosure provides a heat dissipation module. The heat dissipation module includes the aforementioned three-dimensional pulsating heat pipe and a generator set. The three-dimensional coiled structure further has a heat dissipation section. The heat dissipation section and the heat receiving section are respectively located at two opposite sides of the three-dimensional coiled structure. The heat receiving section is configured to be in thermal contact with a heat source, and the heat dissipation section is configured to be in thermal contact with a cold source. The generator set is disposed within the connecting member and configured to convert mechanical energy of rotation into electrical energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present disclosure and wherein: 
         FIG. 1  is a perspective view of a three-dimensional pulsating heat pipe in accordance with a first embodiment of the disclosure; 
         FIG. 2  is a front view of the three-dimensional pulsating heat pipe in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the three-dimensional pulsating heat pipe in  FIG. 1 ; 
         FIG. 4  is another operating position of the three-dimensional pulsating heat pipe in  FIG. 1 ; 
         FIG. 5  is yet another operating position of the three-dimensional pulsating heat pipe in  FIG. 1 ; 
         FIG. 6  is a front view of a three-dimensional pulsating heat pipe in accordance with a second embodiment of the disclosure; 
         FIG. 7  is a front view of a three-dimensional pulsating heat pipe in accordance with a third embodiment of the disclosure; 
         FIG. 8  is a front view of a three-dimensional pulsating heat pipe in accordance with a fourth embodiment of the disclosure; 
         FIG. 9  is another operating position of the three-dimensional pulsating heat pipe in  FIG. 8 ; 
         FIG. 10  is a front view of a three-dimensional pulsating heat pipe in accordance with a fifth embodiment of the disclosure; 
         FIG. 11  is a front view of a three-dimensional pulsating heat pipe in accordance with a sixth embodiment of the disclosure; 
         FIG. 12  is a front view of a heat dissipation module in accordance with a seventh embodiment of the disclosure; 
         FIG. 13  is a front view of a three-dimensional pulsating heat pipe assembly in accordance with an eighth embodiment of the disclosure; 
         FIG. 14  is a front view of a three-dimensional pulsating heat pipe assembly in accordance with a ninth embodiment of the disclosure; 
         FIG. 15  is a perspective view of a heat dissipation module in accordance with a tenth embodiment of the disclosure; 
         FIG. 16  is a front view of the heat dissipation module in  FIG. 15 ; 
         FIG. 17  is a cross-sectional view of one heat dissipation pipe and fillings therein taken along line L 0 -L 0 ′ of  FIG. 16 ; 
         FIG. 18  is a cross-sectional view taken along line L 1 -L 1 ′ of  FIG. 17 ; and 
         FIG. 19  is a cross-sectional view taken along line L 1 -L 2 ′ of  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawings. 
     The drawings may not be drawn to actual size or scale, some exaggerations may be necessary in order to emphasize basic structural relationships, while some are simplified for clarity of understanding, and the present disclosure is not limited thereto. It is allowed to have various adjustments under the spirit of the present disclosure. In the specification, the term “on” may be described as “one is located above another” or “one is in contact with another”. In addition, the terms “top side”, “bottom side”, “above” and “below” are used to illustrate but limit the present disclosure. The term “substantially” is referred to the complete or nearly complete extent or degree of a structure, which means that it is allowable to have tolerance during manufacturing. 
     Please refer to  FIG. 1  to  FIG. 3 ,  FIG. 1  is a perspective view of a three-dimensional pulsating heat pipe in accordance with a first embodiment of the disclosure,  FIG. 2  is a front view of the three-dimensional pulsating heat pipe in  FIG. 1 , and  FIG. 3  is a cross-sectional view of the three-dimensional pulsating heat pipe in  FIG. 1 . 
     The first embodiment provides a three-dimensional pulsating heat pipe (PHP)  1 . The three-dimensional pulsating heat pipe  1  includes a pipe member  10  and a connecting member  30 . 
     The pipe member  10  is coiled around an axis Cm to form a plurality of loop portions  11 , and the loop portions  11  are arranged in order and stacked on one another along the axis C so as to form a three-dimensional coiled structure. That is, these loop portions  11  are stacked together from top to bottom along the axis C to form a stereoscopic three-dimensional coiled structure. 
     Two ends of the pipe member  10  are connected to each other via the connecting member  30 , such that the connecting member  30  and the pipe member  10  together form a closed loop. In such a case, the three-dimensional pulsating heat pipe  1  is also called a closed-loop PHP (CLPHP). Working fluid can be circulated through the closed loop for transferring heat. The connecting member  30  is also configured as a fluid supply for supplying the working fluid (e.g., water, methanol, acetone, or any pure liquid or solution and the like) into the pipe member  10  with a filling ratio of approximately 30 to 80%. 
     The three-dimensional coiled structure has a heat receiving section H and a heat dissipation section D respectively on two opposite sides thereof (e.g., the upper and lower sides of the three-dimensional coiled structure shown in  FIG. 2 ), and the three-dimensional coiled structure further has a first adiabatic section T 1  and a second adiabatic section T 2  located between the heat receiving section H and the heat dissipation section D. The heat receiving section H is also called “evaporator section”, the heat dissipation section D is also called “condenser section”, and the adiabatic section is also called “insulation section”. The heat receiving section H and the heat dissipation section D are respectively configured to be in thermal contact with a heat source and a cold source. The heat source is, for example, a laser diode light, an insulated gate bipolar transistor or a chip processor, and the cold source is, for example, a heat dissipation fins module. 
     In this embodiment, the pipe member  10  in at least a part of one of the adiabatic sections may be compressed and deformed during manufacturing, such that the pipe member  10  in the two adiabatic sections have different effective pipe cross-sectional areas. This causes the adiabatic sections to have different flow resistances, such that the working fluid tends to flow towards the side that has a relatively small flow resistance, thereby increasing the flow rate of the working fluid. 
     In detail, as shown in  FIG. 3 , in this embodiment, a portion of the pipe member  10  which is located in the first adiabatic section T 1  had been compressed and deformed so that the pipe member  10  in the first adiabatic section T 1  is in a flat shape; another portion of the pipe member  10  which is located in the second adiabatic section T 2  remain the same so that the pipe member  10  in the second adiabatic section T 2  remains in a round shape. In such a case, the pipe member  10  in the first adiabatic section T 1  has a larger effective pipe cross-section area compared to that in the second adiabatic section T 2 . The effective pipe cross-sectional area means an area on the cross-portion of the pipe member  10  where the working fluid is allowed to flow through. Specifically, the pipe member  10  in the first adiabatic section T 1  has a first effective pipe cross-sectional area A 1 , and the pipe member  10  in the second adiabatic section T 2  has a second effective pipe cross-sectional area A 2  which is smaller than the first effective pipe cross-sectional area A 1 , such that the flow resistance in the first adiabatic section T 1  is larger than that in the second adiabatic section T 2 . As such, when the heat receiving section H receives heat to heat and vaporize the working fluid, and a pressure difference created thereby between the heat receiving section H and the heat dissipation section D pushes the liquid-vapor mixture of the working fluid to flow, the liquid-vapor mixture of the working fluid in the heat receiving section H tends to flow towards the second adiabatic section T 2 . Therefore, in the closed loop, the working fluid tends to flow along a specific direction (e.g., direction F in the figure) and to automatically form a circulation, which helps to increase the flow rate of the working fluid. In this embodiment, a ratio of the first effective pipe cross-sectional area A 1  to the second effective pipe cross-sectional area A 2  ranges from, for example, 0.3 to 0.7. 
     In the three-dimensional pulsating heat pipe  1 , the adjacent loop portions  11  are in tight contact with each other in order to prevent the existence of a gap in the axial direction C therebetween. This helps to prevent an invalid contact area between the heat receiving section H and the heat source so as to maximum heat transfer rate, but the present disclosure is not limited thereto. In other embodiments, there can be a gap between the adjacent loop portions. Additionally, in this embodiment, since the pipe member of the three-dimensional pulsating heat pipe is coiled around an axis to form the loop portions and the loop portions are tightly stacked on one another, the loop portions together form a compact contact surface with small or no gaps thereon, such that the three-dimensional pulsating heat pipe does not require a small radius of curvature of the pipe member to increase effective thermal contact area, thereby does not require additional specific jigs for bending task, either. Accordingly, the three-dimensional pulsating heat pipe of the present disclosure features low manufacturing cost in comparison with the conventional pulsating heat pipes. 
     In this embodiment, the pipe member  10  is made of, for example, copper, thus the three-dimensional pulsating heat pipe  1  features a high thermal conductivity contributed by the property of copper. However, the present disclosure is not limited to the materials of the pipe member. In other embodiments, the pipe member  10  may be made of other materials that also have a high thermal conductivity. 
     Furthermore, based on a theoretical inner diameter range of a pulsating heat pipe, the inner diameter of the pipe member  10  can be determined according to the type of the working fluid; by doing so, the working fluid can form into interspersed vapor bubbles (also called “vapor plugs”) and liquid slugs in the pipe member  10 ; in the other words, the working fluid can be separated into different segments of liquid slugs that are spaced apart and separated by vapor bubbles within the closed loop of the pipe member  10 . For example, in the case that the working fluid is mercury or sodium, the inner diameter of the pipe member  10  may range from 1.0 mm to 8.0 mm; in the case that the working fluid is water, the inner diameter of the pipe member  10  may range from 1.0 mm to 5.0 mm. 
     In this embodiment, the heat receiving section H is located at a level lower than the heat dissipation section D; that is, the heat receiving section H is located underneath the heat dissipation section D. In such a case, the three-dimensional pulsating heat pipe is defined as being in a positive 90-degree position (or in an upright position). As such, the heated vapor bubbles of the working fluid are able to push liquid-vapor mixture of the working fluid to flow upwards to the heat dissipation section D due to buoyancy of the vapor bubbles. That is, the pressure difference forces the liquid slugs and vapor bubbles to move between the heat receiving section H and the heat dissipation section D. 
     It is noted that the three-dimensional pulsating heat pipe  1  is able to operate in another position. Please refer to  FIG. 4  and  FIG. 5 .  FIG. 4  is another operating position of the three-dimensional pulsating heat pipe in  FIG. 1 , and  FIG. 5  is yet another operating position of the three-dimensional pulsating heat pipe in  FIG. 1 . 
     As described above, the working fluid automatically flows along a specific direction due to the unbalanced flow resistance on two sides of the heat receiving section H caused by the difference between the effective pipe cross-sectional areas of the adiabatic sections T 1  and T 2 , and thus the three-dimensional pulsating heat pipe  1  is still able to operate at the desired level for cooling whether it is being placed horizontally (as shown in  FIG. 4 ) or being placed in a negative 90-degree position (as shown in  FIG. 5 , the three-dimensional pulsating heat pipe  1  is in an upside-down position compared to  FIG. 2 ). As shown in the figures, when the three-dimensional pulsating heat pipe  1  is placed horizontally, the heat receiving section H and the heat dissipation section D are located at the same level; when the three-dimensional pulsating heat pipe  1  is placed in the negative 90-degree position, the heat receiving section H is located at a level higher than the heat dissipation section D (i.e., the heat receiving section H is located above the heat dissipation section D). In more detail, since there exists a difference in flow resistance (or pressure difference) on two sides of the heat receiving section H, when the three-dimensional pulsating heat pipe  1  is placed in the negative 90-degree position and the vapor bubbles is heated to expand its volume in the heat receiving section H, the vapor bubbles tend to flow towards where the flow resistance is relatively small and therefore to push the liquid slugs towards the heat dissipation section D underneath the heat receiving section H, forming a flow circulation in the closed loop. 
     Table 1 shows a comparison between simulation results of the three-dimensional pulsating heat pipe  1  respectively operating in the positive 90-degree position and in the negative 90-degree position. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Positive 
                 Negative 
               
               
                 Operating position 
                 90-degree position 
                 90-degree position 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Average temperature at heat 
                 114 
                 117 
               
               
                 receiving section (° C.) 
               
               
                 Thermal resistance (K/W) 
                 0.0764 
                 0.0799 
               
               
                   
               
               
                 Note: 
               
               
                 the heating power form the heat source to the heat receiving section is 800 W. 
               
            
           
         
       
     
     As seen in Table 1, a performance degradation rate is only 5% when the three-dimensional pulsating heat pipe  1  is operating in the negative 90-degree position compared to operating in the positive 90-degree position. The performance degradation rate is a ratio between the thermal resistances. Therefore, according to Table 1, the cooling effect provided by the three-dimensional pulsating heat pipe  1  in the negative 90-degree position is as good as the cooling effect provided by the three-dimensional pulsating heat pipe  1  in the positive 90-degree position. 
     In addition, Table 2 shows a comparison between simulation results of the three-dimensional pulsating heat pipe  1  and a conventional pulsating heat pipe both in the positive 90-degree position. Said conventional pulsating heat pipe is a flat capillary pipe. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Three-dimensional 
                 Conventional 
               
               
                   
                 pulsating heat pipe 1 
                 pulsating heat pipe 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Operating position 
                 Positive 90-degree 
                 Positive 90-degree 
               
               
                   
                 position 
                 position 
               
               
                 Filling volume (ml) 
                 30 
                 21 
               
               
                 Filling ratio 
                 35% ± 5% 
                 35% ± 5% 
               
               
                 Heating power (W) 
                 600 
                 300 
               
               
                 Average temperature at heat 
                 105 
                 100 
               
               
                 receiving section (° C.) 
               
               
                 Area of heat receiving 
                 30 
                 75 
               
               
                 section (cm 2 ) 
               
               
                 Heat transmission distance 
                 35 
                 30 
               
               
                 (cm) 
               
               
                 Maximum heat flux 
                 20 
                 4 
               
               
                 (W/cm 2 ) 
               
               
                   
               
            
           
         
       
     
     According to Table 2, the maximum heat flux of the conventional pulsating heat pipe is 4 W/cm 2 , and the maximum heat flux of the three-dimensional pulsating heat pipe  1  is 20 W/cm 2  and is approximately five times larger than the maximum heat flux of the conventional pulsating heat pipe. 
     As shown in  FIG. 4 , in the case that the heat receiving section H, the heat dissipation section D, the first adiabatic section T 1  and the second adiabatic section T 2  of the three-dimensional pulsating heat pipe  1  are all located at the same level; that is, the three-dimensional pulsating heat pipe  1  in  FIG. 4  is placed horizontally. However, the present disclosure is not limited thereto. In other embodiments, when the heat receiving section and the heat dissipation section are located at the same level, the first adiabatic section and the second adiabatic section may be located at different level; that is, one of the first adiabatic section and the second adiabatic section may be placed in contact with the ground. 
     In this embodiment, the pipe member  10  in the entire first adiabatic section T 1  are in a flat shape, but the present disclosure is not limited thereto. In other embodiments, there may be only a portion of the first adiabatic section been compressed and deformed, such that only a portion of the first adiabatic section has a smaller effective pipe cross-sectional area. In another embodiment, it may compress and deform both the first adiabatic section and the second adiabatic section, but the first adiabatic section and the second adiabatic section still have different cross-sectional areas. Furthermore, in yet another embodiment, it may also compress and deform the heat receiving section and the heat dissipation section. For example, in one configuration, it may compress and deform both the first adiabatic section and the heat receiving section, and the pipe member  10  in both the second adiabatic section and the heat dissipation section remains in round pipe; in another configuration, it may compress and deform the first adiabatic section, the heat receiving section and the heat dissipation section, and the pipe member  10  in the second adiabatic section remains in round pipe. 
     In addition, the present disclosure is not limited to the shape of pipe in the first adiabatic section T 1  and the second adiabatic section T 2 . In other embodiments, the pipe member in the first adiabatic section and the second adiabatic section may respectively have a square shape and a round shape that have different effective pipe cross-sectional areas; alternatively, the pipe member in both the first adiabatic section and the second adiabatic section may be in a round shape and have different effective pipe cross-sectional areas. 
     In this embodiment, the three-dimensional coiled structure is rectangular, and the heat receiving section H and the heat dissipation section D are substantially the same in length, but the present disclosure is not limited thereto. In other embodiments, the three-dimensional coiled structure may be formed in other shapes and the heat receiving section and the heat dissipation section may be different in length. For example, please refer to  FIG. 6 , which is a front view of a three-dimensional pulsating heat pipe in accordance with a second embodiment of the disclosure. It is noted that a detailed description of the similar features between the first embodiment and the following embodiments may not be repeated. 
     The second embodiment provides a three-dimensional pulsating heat pipe  1   b.  The three-dimensional pulsating heat pipe  1   b  has a configuration similar to that of the three-dimensional pulsating heat pipe  1  in the first embodiment. One of the differences between these two embodiments is that the three-dimensional pulsating heat pipe  1   b  has a three-dimensional coiled structure being trapezoidal. In such a case, a heat receiving section Hb and a heat dissipation section Db are different in length. As shown in  FIG. 6 , the length of the heat dissipation section Db is larger than the length of the heat receiving section Hb, but the present disclosure is not limited thereto. In other embodiments, the length of the heat receiving section may be larger than the length of the heat dissipation section. 
     However, the present disclosure is not limited thereto. In other embodiments, the three-dimensional coiled structure may be triangular, in an L or oval shape. For example, please refer to  FIG. 7 , which is a front view of a three-dimensional pulsating heat pipe in accordance with a third embodiment of the disclosure. 
     The third embodiment provides a three-dimensional pulsating heat pipe  1   c.  The three-dimensional pulsating heat pipe  1   c  has a configuration similar to that of the three-dimensional pulsating heat pipe  1  in the first embodiment. One of the differences between these two embodiments is that the three-dimensional pulsating heat pipe  1   c  has a three-dimensional coiled structure being triangular. In detail, the three-dimensional coiled structure has two heat dissipation sections Dc and a heat receiving section Hc respectively located on different sides of the triangle. 
     Then, please refer to  FIG. 8  and  FIG. 9 .  FIG. 8  is a front view of a three-dimensional pulsating heat pipe in accordance with a fourth embodiment of the disclosure, and  FIG. 9  is another operating position of the three-dimensional pulsating heat pipe in  FIG. 8 . 
     The fourth embodiment provides a three-dimensional pulsating heat pipe  1   d.  The three-dimensional pulsating heat pipe  1   d  has a configuration similar to that of the three-dimensional pulsating heat pipe  1  in the first embodiment. One of the differences between these two embodiments is that the three-dimensional pulsating heat pipe  1   d  has a heat receiving section Hd and a heat dissipation section Dd respectively located on two opposite long sides of a three-dimensional coiled structure, and the heat receiving section Hd and the heat dissipation section Dd are respectively located close to the diagonal corners of the three-dimensional coiled structure. 
     In addition, the three-dimensional pulsating heat pipe  1   d  may operate in different positions since the three-dimensional coiled structure has different effective pipe cross-sectional areas on two sides thereof (e.g., the two long sides of the three-dimensional coiled structure adjacent to the heat receiving section Hd). For example, the three-dimensional pulsating heat pipe  1   d  can be placed upside down as shown in  FIG. 9 . In this position, the heat receiving section Hd is located above the heat dissipation section Dd, and the three-dimensional pulsating heat pipe  1   d  is still able to perform at a desired level. 
     Then, please refer to  FIG. 10 , which is a front view of a three-dimensional pulsating heat pipe in accordance with a fifth embodiment of the disclosure. The fifth embodiment provides a three-dimensional pulsating heat pipe  1   e.  The three-dimensional pulsating heat pipe  1   e  has a configuration similar to that of the three-dimensional pulsating heat pipe  1  in the first embodiment. The three-dimensional pulsating heat pipe le has a three-dimensional coiled structure forming a storage space  100   e , and the storage space  100   e  is configured for an object  50   e  to be placed therein. That is, the three-dimensional coiled structure of the three-dimensional pulsating heat pipe le can also be taken as a storage frame for efficiently utilizing the available space in the three-dimensional coiled structure. The object  50   e  may be, for example, a circuit structure, a mechanism or a heat-dissipation unit, but the disclosure is not limited thereto. 
     In this or another embodiment, the heat receiving section of the three-dimensional coiled structure may be longer for in thermal contact with more than one heat sources. For example, please refer to  FIG. 11 , which is a front view of a three-dimensional pulsating heat pipe in accordance with a sixth embodiment of the disclosure. 
     The sixth embodiment provides a three-dimensional pulsating heat pipe  1   f.  The three-dimensional pulsating heat pipe  1   f  has a configuration similar to that of the three-dimensional pulsating heat pipe  1  in the first embodiment. One of the differences between these two embodiments is that the three-dimensional pulsating heat pipe  1   f  has a heat receiving section Hf longer than a heat dissipation section Df, allowing the heat receiving section Hf to be in thermal contact with more than one heat sources HS. 
     In addition, the disclosure is not limited to the connecting member as discussed in the previous embodiments. In other embodiments, the connecting member may contain a generator set that can generate electricity by being driven by the working fluid. Specifically, please refer to  FIG. 12 , which is a front view of a heat dissipation module in accordance with a seventh embodiment of the disclosure. 
     The seventh embodiment provides a heat dissipation module including a connecting member  30   g , a generator set  70   g , a fan  80   g , a transmission cable  90   g  and a three-dimensional pulsating heat pipe  1   g.  The three-dimensional pulsating heat pipe lg has a configuration similar to that of the three-dimensional pulsating heat pipe  1  in the first embodiment. As shown in the figure, the three-dimensional pulsating heat pipe  1   g  has a heat receiving section Hg, a first adiabatic section T 1   g,  a second adiabatic section T 2   g  and a heat dissipation section Dg. And there are a heat source HS in thermal contact with the heat receiving section Hg and a cold source DS in thermal contact with the heat dissipation section Dg. In this embodiment, the second adiabatic section T 2   g  has a smaller effective pipe cross-sectional area than the first adiabatic section Tlg, such that, as discussed in the previous embodiments, the working fluid in the three-dimensional pulsating heat pipe  1   g  tends to flow along a direction Fg shown in  FIG. 12  as the heat receiving section Hg receives heat produced by the heat source HS. 
     In addition, the generator set  70   g  is located in the connecting member  30   g  and electrically connected to the fan  80   g  via the transmission cable  90   g . In more detail, the connecting member  30   g  has a chamber  300   g  connected to the closed loop in the three-dimensional pulsating heat pipe  1   g.  The generator set  70   g  includes a generator  710   g  and a blade wheel  730   g  which are located in the chamber  300   g . Specifically, the generator  710   g  has a transmission shaft  711   g , and the blade wheel  730   g  is fixed on the transmission shaft  711   g . The fan  80   g  is disposed in a storage space  100   g  of the three-dimensional coiled structure of the three-dimensional pulsating heat pipe  1   g  and disposed near the heat receiving section Hg, and the transmission cable  90   g  is electrically connected to the generator  710   g  and the fan  80   g.    
     In such a configuration, while the working fluid flows through the connecting member  30   g , it forces the blade wheel  730   g  to spin so as to spin the transmission shaft  711   g , such that the transmission shaft  711   g  drives the generator  710   g  to produce electrical energy. Electrical energy is transmitted to the fan  80  via the transmission cable  90   g . As a result, the fan  80   g  is activated and blows air towards the heat receiving section Hg for cooling. 
     Accordingly, the heat energy produced by the heat source HS forces the working fluid to flow, and the kinetic energy of the working fluid is turned into mechanical energy of rotation and then turned into electrical energy by the generator set  70   g . In short, due to the generator set  70   g , the heat dissipation module is allowed to utilize the waste heat from the heat source HS. 
     Then, please refer to  FIG. 13 , which is a front view of a three-dimensional pulsating heat pipe assembly in accordance with an eighth embodiment of the disclosure. The eighth embodiment provides a three-dimensional pulsating heat pipe assembly  9   h  including two three-dimensional pulsating heat pipes  91   h  and  92   h  that are similar in configuration but different in size. The three-dimensional pulsating heat pipe  91   h  has a three-dimensional coiled structure forming a storage space  9100   h , and the three-dimensional pulsating heat pipe  92   h  is disposed in the storage space  9100   h . Therefore, the three-dimensional pulsating heat pipe assembly  9   h  is a dual-layer heat transfer module, and the heat source HS can be thermally disposed between the three-dimensional pulsating heat pipes  91   h  and  92   h.    
     In addition, the three-dimensional pulsating heat pipes  91   h  and  92   h  may be filled with the same or different types of working fluids for operating in the same or difference working temperatures. For example, in the case that the pressure in the closed loop is approximately 0.3 atmospheres and the working fluid is water, the working fluid starts to evaporate as it is heated to 69° C. for circulating the working fluid; in the case that the pressure is the same and the working fluid is acetone, the working fluid only needs to be heated to 37° C. to start to evaporate. As such, the three-dimensional pulsating heat pipes  91   h  and  92   h  can be filled with different types of working fluids in order to deal with different areas of the heat source or different heat sources that have different temperatures. 
     Then, please refer to  FIG. 14 , which is a front view of a three-dimensional pulsating heat pipe assembly in accordance with a ninth embodiment of the disclosure. 
     The ninth embodiment provides a three-dimensional pulsating heat pipe assembly  9   k  including two three-dimensional pulsating heat pipes  91   k  and  92   k  that have a configuration similar to that of the three-dimensional pulsating heat pipe  1  in the first embodiment but each is a L-shaped three-dimensional coiled structure. In such a case, each of the three-dimensional pulsating heat pipes  91   k  and  92   k  has a heat receiving section Hk and a heat dissipation section Dk located on two opposite ends of the L-shaped three-dimensional coiled structure. As shown in the figure, the three-dimensional pulsating heat pipes  91   k  and  92   k  may be placed in a mirror-symmetrical manner, such that their heat receiving sections Hk are located away from each other for cooling two heat sources HS and their heat dissipation sections Dk are located adjacent to each other to be adjacent to one or more cold sources DS. 
     Then, please refer to  FIG. 15  to  FIG. 19 ,  FIG. 15  is a perspective view of a heat dissipation module in accordance with a tenth embodiment of the disclosure,  FIG. 16  is a front view of the heat dissipation module in  FIG. 15 ,  FIG. 17  is a cross-sectional view of one heat dissipation pipe and fillings therein taken along line L 0 -L 0 ′ of  FIG. 16 ,  FIG. 18  is a cross-sectional view taken along line L 1 -L 1 ′ of  FIG. 17 , and  FIG. 19  is a cross-sectional view taken along line L 1 -L 2 ′ of  FIG. 17 . 
     The tenth embodiment provides a heat dissipation module lm that is applicable to an electronic device such as a projector (not shown). The heat dissipation module  1   m  includes a fin-and-tube heat exchanger  40   m , a plurality of fillings  60   m , a plurality of pipe members  101   m  to  105   m  and a connecting member  30   m.    
     The fin-and-tube heat exchanger  40   m  includes a plurality of fins  410   m  and a plurality of heat dissipation pipes  431   m  to  435   m . The heat dissipation pipes  431   m  to  435   m  are respectively disposed through the fins  410   m . The fillings  60   m  are, for example, hollow tubes disposed in the heat dissipation pipes  431   m  to  435   m.    
     The pipe members  101   m  to  105   m , the heat dissipation pipes  431   m  to  435   m  and the connecting member  30   m  are connected in series to form a closed loop. In detail, one end of the pipe member  101   m  is connected to one end of the heat dissipation pipe  431   m,  two ends of the pipe member  102   m  are respectively connected to one end of the heat dissipation pipe  432   m  and the other end of the heat dissipation pipe  431   m,  two ends of the pipe member  103   m  are respectively connected to one end of the heat dissipation pipe  433   m  and the other end of the heat dissipation pipe  432 m, two ends of the pipe member  104   m  are respectively connected to one end of the heat dissipation pipe  434   m  and the other end of the heat dissipation pipe  433   m , two ends of the pipe member  105   m  are respectively connected to one end of the heat dissipation pipe  435   m  and the other end of the heat dissipation pipe  434   m . As such, the pipe members  101   m  to  105   m , the heat dissipation pipes  431   m  to  435   m  together form a continuous flow path. The connecting member  30   m  is connected to two ends of the continuous flow path (e.g., the connecting member  30   m  is connected to the pipe member  101   m  and the heat dissipation pipe  435   m ) so as to form the closed loop. 
     In addition, the continuous flow path surrounds an axis Cm to form a plurality of loop portions  11   m , and the loop portions  11   m  are arranged in order along the axis Cm so as to form a three-dimensional coiled structure. The three-dimensional coiled structure has a heat receiving section Hm on one side thereof, and the fin-and-tube heat exchanger  40   m  is located on the side opposite to the heat receiving section Hm. In addition, the three-dimensional coiled structure further has a first adiabatic section T 1   m  and a second adiabatic section T 2   m  located between the heat receiving section Hm and the fin-and-tube heat exchanger  40   m.    
     The pipe members  101   m  to  105   m  in the first adiabatic section T 1   m  each have an effective pipe cross-sectional area different from that in the second adiabatic section T 2   m.  And a working fluid can be filled in the closed loop for transferring heat. 
     In addition, the connecting member  30  may be connected to an external fluid source (not shown) so as to receive working fluid and provide it into the closed loop. As the closed loop is filled to the desired filling ration, the connecting member  30   m  and the external fluid source may be disconnected and sealed, but the disclosure is not limited thereto. In other embodiments, in order to repeatedly fill the working fluid, the joint between the connecting member  30  and the external fluid source may be replaced by a vacuum safety valve. It is noted that the connecting members  30   m  may be applied to other embodiments. 
     It is specified that the pipe cross-sectional area of each of the heat dissipation pipes  431   m  to  435   m  is larger than a theoretical critical area of a pulsating heat pipe. As such, the working fluid may not form an interspersed vapor bubbles and liquid slugs in the heat dissipation pipes  431   m  to  435   m,  thereby unable to satisfy the operation requirements of a pulsating heat pipe. Therefore, in this embodiment, the heat dissipation pipes  431   m  to  435   m  are filled with the fillings  60   m  (as shown in  FIG. 17 ), and the inner diameter of the fillings  60   m  and the effective hydraulic diameter of the cross-sectional area of each channel formed in the heat dissipation pipes  431   m  to  435   m  satisfy the theoretical inner diameter range of a pulsating heat pipe, allowing the existence of an interspersed vapor bubbles and liquid slugs in the heat dissipation pipes  431   m  to  435   m  (as shown in  FIG. 18  and  FIG. 19 ). As such, the fillings  60   m  help the closed loop to meet the basic operation requirements of a pulsating heat pipe. 
     However, the disclosure is not limited to the configuration of the fillings  60   m.  In other embodiments, each filling may be solid; in such a case, the working fluid may flow through the gaps among the fillings and the inner surface of the heat dissipation pipe. Therefore, it is understood that the difference in effective pipe cross-sectional area may be achieved by filling a portion of the closed loop. 
     According to the three-dimensional pulsating heat pipe, the three-dimensional pulsating heat pipe assembly and the heat dissipation module as described above, the adjacent loop portions are in tight contact with each other so as to prevent the existence of a gap in the axial direction therebetween, which helps to prevent an invalid contact area between the heat receiving section and the heat source, thereby increasing heat transfer rate. 
     Furthermore, the working fluid automatically flows along a specific direction due to the unbalanced flow resistance on two sides of the heat receiving section caused by difference between the effective pipe cross-sectional areas of the adiabatic sections, thus the three-dimensional pulsating heat pipe is able to operate at the desired level for cooling whether it is being placed horizontally or in an upside-down position. 
     In addition, in some embodiments, since the pipe member of the three-dimensional pulsating heat pipe is coiled around an axis to form the loop portions and the loop portions are tightly stacked on one another, the loop portions together form a compact contact surface with small or no gaps thereon, such that the three-dimensional pulsating heat pipe does not require a small radius of curvature of the pipe member to increase effective thermal contact area, thereby does not require additional specific jigs for bending task, either. Accordingly, the three-dimensional pulsating heat pipe of the present disclosure features low manufacturing cost in comparison with the conventional pulsating heat pipes. 
     Moreover, in yet some embodiments, the three-dimensional coiled structure formed by the three-dimensional pulsating heat pipe is able to accommodate and support one or more objects, such as a circuit structure, a mechanism or a heat-dissipation unit for efficiently utilizing the available space in the three-dimensional coiled structure. 
     Additionally, in still some embodiments, the connecting member further contains a generator set that is able to turn the mechanical energy of rotation of the working fluid into electrical energy for the fan to cool the heat receiving section, thereby utilizing the waste heat from the heat source. 
     Further, the three-dimensional coiled structure is not restricted in shape, and it can be further formed in various shapes, such as rectangle, trapezoid, triangle, oval or in an L shape, according to actual design requirements. Other than that, the three-dimensional coiled structure can be coupled to different heat dissipation pipes in the market, such that the three-dimensional pulsating heat pipe is applicable to various types of heat dissipation modules. 
     The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.