US20100319884A1 - Self-excited oscillating flow heat pipe - Google Patents
Self-excited oscillating flow heat pipe Download PDFInfo
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- US20100319884A1 US20100319884A1 US12/866,550 US86655009A US2010319884A1 US 20100319884 A1 US20100319884 A1 US 20100319884A1 US 86655009 A US86655009 A US 86655009A US 2010319884 A1 US2010319884 A1 US 2010319884A1
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- heat pipe
- heating unit
- self
- connection channel
- working fluid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/04—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/0266—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with separate evaporating and condensing chambers connected by at least one conduit; Loop-type heat pipes; with multiple or common evaporating or condensing chambers
Definitions
- the present invention relates to a self-excited oscillating flow heat pipe.
- the wick-type heat pipe is built into about 90% of recent notebook-type personal computers.
- the maximum heat transport rate in a case where the heat pipe has an outside diameter of about 3 mm, and is installed horizontally is about 12 W.
- the wick-type heat pipe has a problem that heat transport performance significantly decline, when the tube diameter is decreased (made small).
- Nonpatent Document 1 Takao Nagasaki, “Review of Pulsating Heat Pipes, Heat Transfer, Vol. 44, No. 186, 2005, pp. 13 to 17
- the invention has been made in consideration of the above points, and the object thereof is to provide a self-excited oscillating flow heat pipe capable of exhibiting high heat transport performance even if the heat pipe is horizontally installed, without making the tube meander.
- the invention has adopted the following configurations.
- a self-excited oscillating flow heat pipe includes a heating unit having a wick therein; a cooling unit filled with a working fluid; a connection channel which rectilinearly connects the heating unit with the cooling unit, and has a smaller channel cross-sectional area than the channel cross-sectional area of the heating unit; a liquid plug protruding into the connection channel from the cooling unit and containing the working fluid; and a vapor plug within the heating unit containing the vaporized working fluid, wherein the liquid plug oscillates self-excitedly in the connection channel.
- the above self-excited oscillating flow heat pipe may be configured as follows: the working fluid filled into the cooling unit has a free liquid level which is not bound to the internal pressure.
- the above self-excited oscillating flow heat pipe may be configured as follows: the cooling unit has an opening, and the opening is provided with an adjustment unit which adjusts the internal volume of the cooling unit.
- the above self-excited oscillating flow heat pipe may be configured as follows: the ratio of the cross-sectional area of the heating unit and the cross-sectional area of the connection channel is 10:1 to 2:1.
- the self-excited oscillating flow heat pipe of the invention it is possible to provide a self-excited oscillating flow heat pipe capable of exhibiting high heat transportation performance even if the heat pipe is horizontally installed, without making a tube meander.
- FIG. 1A is a cross-sectional schematic of a self-excited oscillating flow heat pipe related to one embodiment of the invention.
- FIG. 1B is a cross-sectional schematic of a modification of the above self-excited oscillating flow heat pipe.
- FIG. 1C is a cross-sectional schematic of a modification of the above self-excited oscillating flow heat pipe.
- FIG. 2 is a view illustrating an experimental method of the self-excited oscillating flow heat pipe, and is a schematic showing an experimental device.
- FIG. 3 is a view showing the time-change of the temperature at several locations along the heat pipe during the self-excited oscillation in the self-excited oscillating flow heat pipe of Example 1.
- FIG. 4 is an enlarged view of FIG. 3 .
- FIG. 5 is a graph showing the relationship between heat transport rate Q and effective thermal conductivity ⁇ eff in self-excited oscillating flow heat pipes of Examples 1 and 2 and Comparative Examples 1 to 3.
- FIG. 6 is a graph showing the relationship between the heat transport rate Q and the effective thermal conductivity ⁇ eff in the self-excited oscillating flow heat pipe of Example 1.
- FIG. 6 also shows theoretical values of the thermal conductivity of a heat pipe of a conventional technique.
- FIGS. 1A to 1C are cross-sectional schematics of a self-excited oscillating flow heat pipe of this embodiment.
- FIGS. 1A to 1C are drawings for explaining the structure of a self-excited oscillating heat pipe. The sizes, thicknesses, or dimensions of shown individual sections may be different from those of an actual self-excited oscillating flow heat pipe.
- the self-excited oscillating flow heat pipe 1 (hereinafter referred to as a heat pipe 1 ) shown in FIG. 1A is generally composed of a working fluid M, a heating unit 2 and a cooling unit 3 , a wick 4 built in the heating unit 2 , and a connection channel 5 which connects the heating unit 2 and the cooling unit 3 together.
- the working fluid M flows into the connection channel 5 from the cooling unit 3 to form a liquid plug L. Additionally, in the heating unit 2 , the working fluid M is vaporized to form a vapor plug B. Heat is transported as the liquid plug L oscillates self-excitedly inside the connection channel 5 .
- heat pipe 1 of this embodiment can operate in any orientation, it is preferable to install and use the pipe 1 horizontally along a longitudinal direction so that effective thermal conductivity can be made high.
- the heating unit 2 is provided with a hollow portion 2 a allowed to communicate with the connection channel 5 .
- the wick 4 is arranged at the inner wall surface of the hollow portion 2 a .
- the cooling unit 3 is a container 3 a which fills the working fluid M in the example shown in FIG. 1A .
- the container 3 a is filled with the working fluid M.
- the working fluid M forms a free liquid level M 1 which faces the outside of the heat pipe 1 and is not bound to the internal pressure of the heat pipe 1 .
- the connection channel 5 is attached to a side wall of the container 3 a .
- the end of the connection channel 5 on the side of the container 3 a is an open end.
- the container 3 a and the connection channel 5 are allowed to communicate with each other through this open end.
- the heating unit 2 and the connection channel 5 are hollow cylindrical tubes made of ceramics, glass, or metal.
- One end 1 a of the heating unit 2 is provided with a sealing member 1 c made of ceramics, glass, or metal.
- the heating unit 2 and the connection channel 5 may be made of borosilicate glass, respectively.
- the channel cross-sectional area of the connection channel 5 is smaller than the channel cross-sectional area of the hollow portion 2 a of the heating unit 2 .
- the cross-sectional shapes of the connection channel 5 and the hollow portion 2 a of the heating unit 2 are substantially circular, and the inner diameter of the connection channel 5 is smaller than the inside diameter of the hollow portion 2 a of the heating unit 2 .
- the channel cross-sectional area of the connection channel 5 is smaller than that of the hollow portion 2 a of the heating unit 2 .
- the inside diameter of the hollow portion 2 a of the heating unit has a preferable range of 3 mm to 6 mm
- the inside diameter of the connection channel 5 has a preferable range of 0.5 mm to 3 mm.
- the heating unit 2 If the channel cross-sectional area ratio, internal diameter ratio, or internal diameter of the heating unit 2 becomes smaller than the above range, since the amount of evaporation of the heating unit 2 is not sufficiently obtained, or the liquid retention capacity of the heating unit 2 is low, the heating unit is brought into a dry-out state, which is not preferable. Additionally, if the channel cross-sectional area ratio, internal diameter ratio, or internal diameter of the heating unit 2 exceeds the above range, the quantity of the fluid held within the heating unit 2 increases, and the heating time required for evaporation increases. Additionally, in a case where a low-temperature working fluid flows in from the cooling unit 3 , evaporation stops, and thereby, self-excited oscillation stops, and the time until evaporation begins by reheating increases. Thus, this is not preferable.
- the heating unit 2 and the connection channel 5 have inside diameters which are different from each other, and have thicknesses which are approximately equal to each other, the outside diameters thereof are also made different. For this reason, a flange portion 9 is formed at a joining portion 8 between the heating unit 2 and the connection channel 5 . The heating unit 2 and the connection channel 5 are joined to each other via the flange portion 9 .
- this configuration is just an example.
- the internal diameters of the heating unit 2 and the connection channel 5 may be made different from each other, the external diameters of both the heating unit 2 and the connection channel 5 may be made approximately equal to each other by increasing the thickness of the connection channel 5 , and the end face of the connection channel 5 may be joined to the end face of the heating unit 2 .
- the inside diameters of the heating unit 2 and the connection channel 5 change suddenly with the joining portion 8 as a border.
- the invention is not limited thereto.
- the inside diameters of the heating unit 2 and the connection channel 5 may be gradually changed in the vicinity of the joining portion 8 .
- connection channel 5 is formed in the shape of a straight line between the heating unit 2 and the cooling unit 3 . Additionally, it is not necessary to form the connection channel 5 related to the invention in the shape of a loop, and the working fluid M just has to oscillate in a reciprocal manner inside the straight connection channel 5 during the operation of the heat pipe 1 .
- straight-line shape means a single tube structure which, unlike a conventional technique, is not bent in the shape of a loop.
- the connection channel 5 may have a slight curve or the like so long as the connection channel generates a self-excited oscillation.
- the oscillation amplitude of the working fluid M during self-excited oscillation depends on the shape and size of the connection channel 5 , for example, the oscillation amplitude in a case where the heating unit 2 is heated with the inside diameter of the heating unit 2 being 5 mm, the inside diameter of the connection channel 5 being 2 mm, and the length of the connection channel 4 being 150 mm, increases so as to be about ⁇ 25 to ⁇ 50 mm.
- the lengths of the heating unit 2 and the connection channel 5 may be appropriately designed according to the above oscillation amplitude.
- the wick 4 may be a conventionally well-known wick so long as the wick is capable of transporting a liquid working fluid by a capillary phenomenon.
- the wick 4 may be, for example, a metal net made of a material having excellent thermal conductivity, such as copper, glass wool, a cottony material such as absorbent cotton, or the like. Additionally, the wick 4 may be filled into the whole region of the heating unit 2 in the longitudinal direction. Otherwise, the wick 4 may be filled into a portion of the heating unit 2 in the longitudinal direction (for example, about 2 ⁇ 3 of a total length in the longitudinal direction) so that one end of the wick 4 coincides with the joining portion 8 between the heating unit 2 and the connection channel 5 .
- the working fluid M has only to be appropriately selected according to the operating temperature of the heat pipe 1 .
- the working fluid M is preferably for example pure water, an organic liquid, such as ethanol, a refrigerant, such as chlorofluocarbon, a liquefied gas, such as ammonia, or the like.
- a deaerated working fluid into the connection channel 5 and the heating unit 2 in advance before the operation of the heat pipe 1 .
- the working fluid M filled into the heating unit 2 is vaporized to form the vapor plug B.
- the working fluid M is extruded from the heating unit 2 by the vapor plug B.
- the working fluid M remains in the connection channel 5 , and forms the liquid plug L. Thereafter, when the working fluid reaches a steady state, evaporation and condensation of the working fluid M take place alternately at the meniscus M of the tip of the liquid plug L. For this reason, the liquid plug L performs a self-excited oscillation in the connection channel 5 .
- connection channel 5 When the connection channel 5 is viewed, it can be confirmed that the meniscus M which becomes a gas liquid interface between the vapor plug B and the liquid plug L oscillates in a reciprocal manner inside the connection channel 5 , and thereby, the existence or nonexistence of a self-excited oscillation can be determined.
- the extruded liquid plug L can be absorbed.
- the above heat pipe 1 includes the working fluid M, and the straight connection channel 5 which is arranged between the heating unit 2 , and the cooling unit 3 and through which the working fluid M circulates.
- the channel cross-sectional area of the connection channel 5 is smaller than the channel cross-sectional area of the heating unit 2 , and the heating unit 2 is provided with the wick 4 . For this reason, the effective thermal conductivity and the maximum amount of heat transport can be made markedly higher compared to the conventional self-excited oscillating flow heat pipe.
- the heating unit 2 is provided with the wick 4 , evaporation of the working fluid M can be stably caused in the heating unit 2 . As a result, the effective thermal conductivity and the maximum amount of heat transport can be further made markedly higher.
- the heating unit 2 and the connection channel 5 are made to directly communicate with each other. For this reason, whenever the meniscus M of the tip of the liquid plug L comes to the joining portion 8 between the heating unit 2 and the connection channel 5 , a portion of the liquid is supplied to the heating unit 2 . Accordingly, the working fluid can be held in the heating unit 2 to always cause evaporation. Thereby, the working fluid can be made to stably perform a self-excited oscillation, and the effective thermal conductivity and the maximum amount of heat transport can be made high.
- the above heat pipe 1 has sufficient high-efficiency simply by using one heat pipe. However, in a case where it is intended to transport a large amount of heat, the number of pipes has only to be increased if necessary, and thus, thermal design becomes easy.
- the effective thermal conductivity and the maximum amount of heat transport can be made high by forming the pipe in the shape of a straight line, without making the pipe meander.
- the above heat pipe 1 can be favorably used for cooling of electronic devices, such as a CPU.
- FIG. 1B Another example of the heat pipe is shown in FIG. 1B .
- the difference between this heat pipe 31 and the heat pipe 1 shown in FIG. 1A is the configuration of the cooling unit.
- a cooling unit 33 of the heat pipe 31 shown in FIG. 1B is a hollow columnar glass tube 33 a made of borosilicate glass.
- the inside diameter of the cooling unit 33 is greater than that of the connection channel 5 .
- An opening 33 b is provided at one end of the glass tube 33 a , and the opening 33 b is sealed with a thin sheet (adjustment unit) 34 made of rubber.
- a working fluid is filled in the cooling unit 33 .
- the outer periphery of the cooling unit 33 is provided with radiating fins 35 .
- the heat pipe 31 a portion of the liquid plug L is extruded to the cooling unit 33 during formation of the vapor plug B and generation of a self-excited oscillation.
- the thin sheet 34 made of rubber provided in the cooling unit 33 deforms, the internal volume of the cooling unit substantially increases and the volume of the extruded liquid plug L can be absorbed.
- a diaphragm may be used instead.
- FIG. 1C still another example of the heat pipe is shown in FIG. 1C .
- the difference between this heat pipe 41 and the heat pipe 31 shown in FIG. 1B is the position of the adjustment unit provided in the cooling unit.
- a cooling unit 43 of the heat pipe 41 shown in FIG. 1C is a hollow columnar glass tube 43 a of which one end made of borosilicate glass is closed.
- the inside diameter of the cooling unit 43 is greater than that of the connection channel 5 .
- An opening 43 b is provided at a side surface of the glass tube 43 a .
- the opening 43 b is sealed with a thin sheet 44 made of rubber (adjustment unit).
- a working fluid is filled in the cooling unit 43 .
- an outer periphery of the cooling unit 43 is provided with radiating fins 45 .
- the heat pipe 41 similarly to the above heat pipe 31 , a portion of the liquid plug L is extruded to the cooling unit 43 during formation of the vapor plug B, and generation of a self-excited oscillation. At this time, as the thin sheet 44 made of rubber provided in the cooling unit 43 deforms, the internal volume of the cooling unit 43 substantially increases, and the volume of the extruded liquid plug L can be absorbed.
- a diaphragm may be used instead of this.
- a glass tube 13 used as the connection channel 5 made of borosilicate glass with an inside diameter of 2 mm and a length of 250 mm, and a glass tube 12 used as the heating unit 2 made of borosilicate glass with an inside diameter of 5 mm and a length of 150 mm were prepared, and the glass tubes 12 and 13 were fused together.
- the wick 14 made of a copper net was mounted on the inner wall of the glass tube 12 .
- the wick 14 was mounted at a distance of 100 mm from the fused portion.
- the portion mounted with the wick 14 was used as the heating unit 2 .
- sealing by a sealing member 11 c of which one end 11 a is made of borosilicate glass was performed.
- a heater 22 was mounted on the heating unit 2 of the heat pipe 11 over a length L of 50 mm, and the heat pipe 11 was substantially horizontally installed. Additionally, the portion immersed in the water bath 21 was used as the cooling unit 3 of the heat pipe 11 . The temperature of cooling water 21 a in the water bath 21 was maintained at 0° C. Meanwhile, the amount of heat generation of the heater 22 was set to such a degree that the temperature of the heating unit was maintained at 100° C., which is the boiling point of the pure water, and the heat pipe 11 was operated.
- the temperature of a measurement location TC 1 is the temperature of the heating unit 2 , and is the surface temperature on the side of one end 11 a of a mounting portion of the heater 22 .
- the temperature of a measurement location TC 2 is the temperature of the heating unit 2 , and is the surface temperature on the side of the other end 11 b of the mounting portion of the heater 22 .
- the temperature of a measurement location TC 3 is the water temperature of the cooling water 22 a .
- the temperature of a measurement location TC 4 is the water temperature immediately behind an outlet of the open end 11 b.
- TC 1 and TC 2 are maintained at about 100° C.
- TC 3 is maintained at about 0° C.
- TC 4 has a periodic peak.
- the maximum temperature of the peak is about 10° C.
- the frequency of the peak becomes 5 Hz.
- the oscillation amplitude of the working fluid 20 is 100 mm ( ⁇ 50 mm) at a maximum. As such, in the heat pipe 11 of Example 1, the self-excited oscillation of the working fluid 20 was observed in the steady state.
- ⁇ is the density of the working fluid 20 (pure water)
- c p is the specific heat at constant pressure of the working fluid 20 (pure water)
- V is the enclosed amount of the working fluid 20
- ⁇ T is the temperature increase of the water in the cooling unit during the time interval ⁇ t.
- L ⁇ 2 is the length of the sum of the total length of the connection channel and 1 ⁇ 2 of the total length of the heating unit
- T H is the temperature of the heating unit
- T L is the water temperature of the cooling water in the water bath
- d ⁇ 2 is the inside diameter of the connection channel.
- Example 2 a heat pipe of Example 2 was fixed up similarly to Example 1 except that quartz glass was used as the material for a heating-side pipe and a cooling-side pipe. Then, similarly to Example 1, the relationship between the heat transport rate Q and the effective thermal conductivity ⁇ eff in the heat pipe of Example 1 was investigated. The results are shown in FIG. 5 .
- Example 1 a heat pipe of Comparative Example 1 was fixed up similarly to Example 1 except that quartz glass was used as the material for a heating-side pipe and a cooling-side pipe, and the wick was not installed. Then, similarly to Example 1, the relationship between the heat transport rate Q and the effective thermal conductivity ⁇ eff in the heat pipe of Comparative Example 1 was investigated. The results are shown in FIG. 5 .
- a glass tube made of quartz glass with an inside diameter of 5 mm and a length of 400 mm was prepared, and a wick made of a copper net was mounted on the inner wall surface of a hollow portion of this glass tube.
- one end of the pipe was sealed by a sealing member.
- the hollow portion was filled with the working fluid 20 (pure water).
- the heat pipe 11 of Comparative Example 2 was fixed up in this way.
- the heat pipe of Embodiment 1 shows 33 W at a maximum, and the effective thermal conductivity ⁇ eff shows 36000 W/(m ⁇ K) at a maximum. Additionally, the heat pipe of Example 2 shows comparable effective thermal conductivity ⁇ eff at the same heat transport rate as Example 1.
- a self-excited oscillating flow heat pipe can be configured by joining two pipes with different inside diameters together, and enclosing a working fluid in the hollow portion of a pipe, and a self-excited oscillation can be developed even when this heat pipe is horizontally installed.
- the heat transport rate and the effective thermal conductivity ⁇ eff are well-correlated, and increases linearly.
- the effective thermal conductivity was increased to about 40000 W/(m ⁇ K) at a maximum. It can be seen that the effective thermal conductivity increases to 100 times the thermal conductivity of copper (400 W/(m ⁇ K)), whose thermal conductivity is comparatively high.
- the temperature (TC 1 , TC 2 ) of the heating unit is maintained near the boiling point of the working fluid (pure water). Since pure water was used this time, the temperature of the heating unit became about 100° C. However, if a suitable working fluid is selected according to the allowable temperature of the object to be cooled, efficient heat conduction can be realized.
- the maximum value of the effective thermal conductivity was about 40000 W/(m ⁇ K), and the maximum value of the heat transport rate was about 50 W.
- these values are not limit values, and superior results may be obtained depending on the change of experimental conditions.
- FIG. 6 is a comparison chart of experimental values of heat transport characteristics of the heat pipe of Example 1, and theoretical values of heat transport characteristics of the heat pipe (dream pipe) of the conventional technique, and shows the relationship between the heat transport rate Q and the effective thermal conductivity ⁇ eff regarding individual heat pipes.
- the heat pipe of this conventional technique is a heat pipe (dream pipe) of a type in which heat is axially transported by forcibly oscillating a liquid within the pipe.
- the effective thermal conductivity ⁇ eff of the dream pipe was calculated from the following Expressions (3) and (4).
- ⁇ is the thermal conductivity of a fluid
- Pr is the Prandt1 number
- r is the tube inside diameter
- ⁇ is the kinematic viscosity of water
- f is the number of oscillations
- S is oscillation amplitude.
- the dream pipe of this conventional technique is of a single diameter tube-type which does not have the connection channel 5 with a smaller diameter than that of the heating unit 2 .
- the effective thermal conductivity of the heat pipe of Example 1 is as large as about 10 times the dream pipe of the conventional technique.
- One of the factors of this effect is considered to be that, in the heat pipe of Example 1, the working fluid M in the glass tube 13 is replaced with a low-temperature liquid in the water bath 21 whenever the working fluid M oscillates, because the open end 11 b of the glass tube 13 is opened into a water bath.
- the self-excited oscillating flow heat pipe of the invention it is possible to provide a self-excited oscillating flow heat pipe capable of exhibiting high heat transport performance even if the heat pipe is horizontally installed, without making a tube meander.
Abstract
A self-excited oscillating flow heat pipe includes a heating unit having a wick therein; a cooling unit filled with a working fluid; a connection channel which rectilinearly connects the heating unit with the cooling unit, and has a smaller channel cross-sectional area than the channel cross-sectional area of the heating unit; a liquid plug protruding into the connection channel from the cooling unit and containing the working fluid; and a vapor plug in the heating unit containing the vaporized working fluid. The liquid plug oscillates self-excitedly in the connection channel.
Description
- The present invention relates to a self-excited oscillating flow heat pipe.
- Priority is claimed on Japanese Patent Application No. 2008-029713 filed on Feb. 8, 2008, the content of which is incorporated herein by reference.
- In recent years, with miniaturization and high integration of electronic devices, the heat generation density of semiconductor elements has been rapidly increasing, and establishment of an efficient heat removal technique has become imperative. However, for example, when miniaturization of electronic apparatuses, such as a notebook-type personal computer, is carried out, for example, it becomes impossible to secure the space for a large-sized heat sink to be installed right above the central processing unit (CPU), which is a heat source. In such a case, it is necessary to transport generated heat to a location where the heat sink can be installed. For this reason, a wick-type heat pipe is utilized as a heat transport means under the present circumstances.
- The wick-type heat pipe is built into about 90% of recent notebook-type personal computers. In such a heat pipe, the maximum heat transport rate in a case where the heat pipe has an outside diameter of about 3 mm, and is installed horizontally is about 12 W. However, the wick-type heat pipe has a problem that heat transport performance significantly decline, when the tube diameter is decreased (made small).
- Thus, a self-excited oscillating flow heat pipe using a phase change with high heat transport performance even if miniaturization has recently attracted attention. However, in a meandering loop-type self-excited oscillating flow heat pipe (inside diameter of about 0.5 mm to 2 mm), which is a representative example of the above heat pipe, there are problems in that it is necessary to make a number of tubes meander, and operation of the heat pipe is difficult when horizontally installed (refer to Nonpatent Document 1).
-
Nonpatent Document 1 Takao Nagasaki, “Review of Pulsating Heat Pipes, Heat Transfer, Vol. 44, No. 186, 2005, pp. 13 to 17 - The invention has been made in consideration of the above points, and the object thereof is to provide a self-excited oscillating flow heat pipe capable of exhibiting high heat transport performance even if the heat pipe is horizontally installed, without making the tube meander.
- In order to achieve the above object, the invention has adopted the following configurations.
- (1) A self-excited oscillating flow heat pipe includes a heating unit having a wick therein; a cooling unit filled with a working fluid; a connection channel which rectilinearly connects the heating unit with the cooling unit, and has a smaller channel cross-sectional area than the channel cross-sectional area of the heating unit; a liquid plug protruding into the connection channel from the cooling unit and containing the working fluid; and a vapor plug within the heating unit containing the vaporized working fluid, wherein the liquid plug oscillates self-excitedly in the connection channel.
- (2) The above self-excited oscillating flow heat pipe may be configured as follows: the working fluid filled into the cooling unit has a free liquid level which is not bound to the internal pressure.
- (3) The above self-excited oscillating flow heat pipe may be configured as follows: the cooling unit has an opening, and the opening is provided with an adjustment unit which adjusts the internal volume of the cooling unit.
- (4) The above self-excited oscillating flow heat pipe may be configured as follows: the ratio of the cross-sectional area of the heating unit and the cross-sectional area of the connection channel is 10:1 to 2:1.
- According to the self-excited oscillating flow heat pipe of the invention, it is possible to provide a self-excited oscillating flow heat pipe capable of exhibiting high heat transportation performance even if the heat pipe is horizontally installed, without making a tube meander.
-
FIG. 1A is a cross-sectional schematic of a self-excited oscillating flow heat pipe related to one embodiment of the invention. -
FIG. 1B is a cross-sectional schematic of a modification of the above self-excited oscillating flow heat pipe. -
FIG. 1C is a cross-sectional schematic of a modification of the above self-excited oscillating flow heat pipe. -
FIG. 2 is a view illustrating an experimental method of the self-excited oscillating flow heat pipe, and is a schematic showing an experimental device. -
FIG. 3 is a view showing the time-change of the temperature at several locations along the heat pipe during the self-excited oscillation in the self-excited oscillating flow heat pipe of Example 1. -
FIG. 4 is an enlarged view ofFIG. 3 . -
FIG. 5 is a graph showing the relationship between heat transport rate Q and effective thermal conductivity λeff in self-excited oscillating flow heat pipes of Examples 1 and 2 and Comparative Examples 1 to 3. -
FIG. 6 is a graph showing the relationship between the heat transport rate Q and the effective thermal conductivity λeff in the self-excited oscillating flow heat pipe of Example 1.FIG. 6 also shows theoretical values of the thermal conductivity of a heat pipe of a conventional technique. -
-
- 1: HEAT PIPE (SELF-EXCITED OSCILLATING FLOW HEAT PIPE)
- 2: HEATING UNIT
- 3, 33, 43: COOLING UNIT
- 4: WICK
- 5: CONNECTION CHANNEL
- 33 b, 43 b: OPENING
- 34, 44: ADJUSTMENT UNIT
- B: VAPOR PLUG
- L: LIQUID PLUG
- M: WORKING FLUID
- M1: FREE LIQUID LEVEL
- Hereinafter, embodiments of the invention will be described with reference to the drawings.
FIGS. 1A to 1C are cross-sectional schematics of a self-excited oscillating flow heat pipe of this embodiment. In addition,FIGS. 1A to 1C are drawings for explaining the structure of a self-excited oscillating heat pipe. The sizes, thicknesses, or dimensions of shown individual sections may be different from those of an actual self-excited oscillating flow heat pipe. - The self-excited oscillating flow heat pipe 1 (hereinafter referred to as a heat pipe 1) shown in
FIG. 1A is generally composed of a working fluid M, aheating unit 2 and a cooling unit 3, awick 4 built in theheating unit 2, and aconnection channel 5 which connects theheating unit 2 and the cooling unit 3 together. - In the
heat pipe 1, the working fluid M flows into theconnection channel 5 from the cooling unit 3 to form a liquid plug L. Additionally, in theheating unit 2, the working fluid M is vaporized to form a vapor plug B. Heat is transported as the liquid plug L oscillates self-excitedly inside theconnection channel 5. - In addition, although the
heat pipe 1 of this embodiment can operate in any orientation, it is preferable to install and use thepipe 1 horizontally along a longitudinal direction so that effective thermal conductivity can be made high. - The
heating unit 2 is provided with ahollow portion 2 a allowed to communicate with theconnection channel 5. Thewick 4 is arranged at the inner wall surface of thehollow portion 2 a. Additionally, the cooling unit 3 is acontainer 3 a which fills the working fluid M in the example shown inFIG. 1A . Thecontainer 3 a is filled with the working fluid M. Additionally, the working fluid M forms a free liquid level M1 which faces the outside of theheat pipe 1 and is not bound to the internal pressure of theheat pipe 1. Additionally, theconnection channel 5 is attached to a side wall of thecontainer 3 a. The end of theconnection channel 5 on the side of thecontainer 3 a is an open end. Thecontainer 3 a and theconnection channel 5 are allowed to communicate with each other through this open end. - The
heating unit 2 and theconnection channel 5 are hollow cylindrical tubes made of ceramics, glass, or metal. Oneend 1 a of theheating unit 2 is provided with a sealingmember 1 c made of ceramics, glass, or metal. Particularly, in this embodiment, theheating unit 2 and theconnection channel 5 may be made of borosilicate glass, respectively. - The channel cross-sectional area of the
connection channel 5 is smaller than the channel cross-sectional area of thehollow portion 2 a of theheating unit 2. In the example shown inFIGS. 1A to 1C , the cross-sectional shapes of theconnection channel 5 and thehollow portion 2 a of theheating unit 2 are substantially circular, and the inner diameter of theconnection channel 5 is smaller than the inside diameter of thehollow portion 2 a of theheating unit 2. Thereby, the channel cross-sectional area of theconnection channel 5 is smaller than that of thehollow portion 2 a of theheating unit 2. - The ratio of the channel cross-sectional area of the
hollow portion 2 a of the heating unit and the channel cross-sectional area of theconnection channel 5 has a preferable range of, for example, heating unit:connection channel=from 10:1 to 2:1. - When a more specific description is made of a case where the invention is applied to water cooling of a CPU of a personal computer, the inside diameter of the
hollow portion 2 a of the heating unit has a preferable range of 3 mm to 6 mm, and the inside diameter of theconnection channel 5 has a preferable range of 0.5 mm to 3 mm. - If the channel cross-sectional area ratio, internal diameter ratio, or internal diameter of the
heating unit 2 becomes smaller than the above range, since the amount of evaporation of theheating unit 2 is not sufficiently obtained, or the liquid retention capacity of theheating unit 2 is low, the heating unit is brought into a dry-out state, which is not preferable. Additionally, if the channel cross-sectional area ratio, internal diameter ratio, or internal diameter of theheating unit 2 exceeds the above range, the quantity of the fluid held within theheating unit 2 increases, and the heating time required for evaporation increases. Additionally, in a case where a low-temperature working fluid flows in from the cooling unit 3, evaporation stops, and thereby, self-excited oscillation stops, and the time until evaporation begins by reheating increases. Thus, this is not preferable. - Additionally, since the
heating unit 2 and theconnection channel 5 have inside diameters which are different from each other, and have thicknesses which are approximately equal to each other, the outside diameters thereof are also made different. For this reason, a flange portion 9 is formed at a joining portion 8 between theheating unit 2 and theconnection channel 5. Theheating unit 2 and theconnection channel 5 are joined to each other via the flange portion 9. However, this configuration is just an example. As another example, for example, the internal diameters of theheating unit 2 and theconnection channel 5 may be made different from each other, the external diameters of both theheating unit 2 and theconnection channel 5 may be made approximately equal to each other by increasing the thickness of theconnection channel 5, and the end face of theconnection channel 5 may be joined to the end face of theheating unit 2. - Additionally, in the example shown in
FIGS. 1A to 1C , the inside diameters of theheating unit 2 and theconnection channel 5 change suddenly with the joining portion 8 as a border. However, the invention is not limited thereto. The inside diameters of theheating unit 2 and theconnection channel 5 may be gradually changed in the vicinity of the joining portion 8. - The
connection channel 5, as shown inFIGS. 1A to 1C , is formed in the shape of a straight line between theheating unit 2 and the cooling unit 3. Additionally, it is not necessary to form theconnection channel 5 related to the invention in the shape of a loop, and the working fluid M just has to oscillate in a reciprocal manner inside thestraight connection channel 5 during the operation of theheat pipe 1. Here, the term straight-line shape means a single tube structure which, unlike a conventional technique, is not bent in the shape of a loop. Although it is preferable that theconnection channel 5 be substantially straight, the connection channel may have a slight curve or the like so long as the connection channel generates a self-excited oscillation. - Although the oscillation amplitude of the working fluid M during self-excited oscillation depends on the shape and size of the
connection channel 5, for example, the oscillation amplitude in a case where theheating unit 2 is heated with the inside diameter of theheating unit 2 being 5 mm, the inside diameter of theconnection channel 5 being 2 mm, and the length of theconnection channel 4 being 150 mm, increases so as to be about ±25 to ±50 mm. The lengths of theheating unit 2 and theconnection channel 5 may be appropriately designed according to the above oscillation amplitude. - The
wick 4 may be a conventionally well-known wick so long as the wick is capable of transporting a liquid working fluid by a capillary phenomenon. Thewick 4 may be, for example, a metal net made of a material having excellent thermal conductivity, such as copper, glass wool, a cottony material such as absorbent cotton, or the like. Additionally, thewick 4 may be filled into the whole region of theheating unit 2 in the longitudinal direction. Otherwise, thewick 4 may be filled into a portion of theheating unit 2 in the longitudinal direction (for example, about ⅔ of a total length in the longitudinal direction) so that one end of thewick 4 coincides with the joining portion 8 between theheating unit 2 and theconnection channel 5. - The working fluid M has only to be appropriately selected according to the operating temperature of the
heat pipe 1. The working fluid M is preferably for example pure water, an organic liquid, such as ethanol, a refrigerant, such as chlorofluocarbon, a liquefied gas, such as ammonia, or the like. - It is preferable to completely fill a deaerated working fluid into the
connection channel 5 and theheating unit 2 in advance before the operation of theheat pipe 1. By heating theheating unit 2 of theheat pipe 1, the working fluid M filled into theheating unit 2 is vaporized to form the vapor plug B. The working fluid M is extruded from theheating unit 2 by the vapor plug B. The working fluid M remains in theconnection channel 5, and forms the liquid plug L. Thereafter, when the working fluid reaches a steady state, evaporation and condensation of the working fluid M take place alternately at the meniscus M of the tip of the liquid plug L. For this reason, the liquid plug L performs a self-excited oscillation in theconnection channel 5. When theconnection channel 5 is viewed, it can be confirmed that the meniscus M which becomes a gas liquid interface between the vapor plug B and the liquid plug L oscillates in a reciprocal manner inside theconnection channel 5, and thereby, the existence or nonexistence of a self-excited oscillation can be determined. - Additionally, although a portion of the liquid plug L is extruded to the cooling unit 3 (
container 3 a) during formation of the vapor plug B and generation of a self-excited oscillation, since the working fluid M filled into thecontainer 3 a has a free liquid level M1, the extruded liquid plug L can be absorbed. - The
above heat pipe 1 includes the working fluid M, and thestraight connection channel 5 which is arranged between theheating unit 2, and the cooling unit 3 and through which the working fluid M circulates. The channel cross-sectional area of theconnection channel 5 is smaller than the channel cross-sectional area of theheating unit 2, and theheating unit 2 is provided with thewick 4. For this reason, the effective thermal conductivity and the maximum amount of heat transport can be made markedly higher compared to the conventional self-excited oscillating flow heat pipe. - Particularly, since the
heating unit 2 is provided with thewick 4, evaporation of the working fluid M can be stably caused in theheating unit 2. As a result, the effective thermal conductivity and the maximum amount of heat transport can be further made markedly higher. - Additionally, in a case where the
above heat pipe 1 is horizontally installed, a self-excited oscillation can be stably maintained. - Moreover, according to the
above heat pipe 1, theheating unit 2 and theconnection channel 5 are made to directly communicate with each other. For this reason, whenever the meniscus M of the tip of the liquid plug L comes to the joining portion 8 between theheating unit 2 and theconnection channel 5, a portion of the liquid is supplied to theheating unit 2. Accordingly, the working fluid can be held in theheating unit 2 to always cause evaporation. Thereby, the working fluid can be made to stably perform a self-excited oscillation, and the effective thermal conductivity and the maximum amount of heat transport can be made high. - The
above heat pipe 1 has sufficient high-efficiency simply by using one heat pipe. However, in a case where it is intended to transport a large amount of heat, the number of pipes has only to be increased if necessary, and thus, thermal design becomes easy. - Additionally, in the conventional meandering loop-type heat pipe, desired performance can not be exhibited unless the pipe is made to meander many times. However, according to the above heat pipe, the effective thermal conductivity and the maximum amount of heat transport can be made high by forming the pipe in the shape of a straight line, without making the pipe meander.
- Additionally, the
above heat pipe 1 can be favorably used for cooling of electronic devices, such as a CPU. - Next, another example of the heat pipe is shown in
FIG. 1B . The difference between thisheat pipe 31 and theheat pipe 1 shown inFIG. 1A is the configuration of the cooling unit. - A cooling
unit 33 of theheat pipe 31 shown inFIG. 1B is a hollowcolumnar glass tube 33 a made of borosilicate glass. The inside diameter of the coolingunit 33 is greater than that of theconnection channel 5. Anopening 33 b is provided at one end of theglass tube 33 a, and theopening 33 b is sealed with a thin sheet (adjustment unit) 34 made of rubber. A working fluid is filled in thecooling unit 33. - Additionally, the outer periphery of the cooling
unit 33 is provided with radiatingfins 35. - According to the
heat pipe 31, a portion of the liquid plug L is extruded to thecooling unit 33 during formation of the vapor plug B and generation of a self-excited oscillation. However, as thethin sheet 34 made of rubber provided in thecooling unit 33 deforms, the internal volume of the cooling unit substantially increases and the volume of the extruded liquid plug L can be absorbed. In this example, although the thin sheet made of rubber has been used as the adjustment unit, a diaphragm may be used instead. - Next, still another example of the heat pipe is shown in
FIG. 1C . The difference between thisheat pipe 41 and theheat pipe 31 shown inFIG. 1B is the position of the adjustment unit provided in the cooling unit. - A cooling
unit 43 of theheat pipe 41 shown inFIG. 1C is a hollowcolumnar glass tube 43 a of which one end made of borosilicate glass is closed. The inside diameter of the coolingunit 43 is greater than that of theconnection channel 5. Anopening 43 b is provided at a side surface of theglass tube 43 a. Theopening 43 b is sealed with athin sheet 44 made of rubber (adjustment unit). A working fluid is filled in thecooling unit 43. - Additionally, an outer periphery of the cooling
unit 43 is provided with radiatingfins 45. - According to the
heat pipe 41, similarly to theabove heat pipe 31, a portion of the liquid plug L is extruded to thecooling unit 43 during formation of the vapor plug B, and generation of a self-excited oscillation. At this time, as thethin sheet 44 made of rubber provided in thecooling unit 43 deforms, the internal volume of the coolingunit 43 substantially increases, and the volume of the extruded liquid plug L can be absorbed. In this example, although the thin sheet made of rubber has been used as the adjustment unit, a diaphragm may be used instead of this. - Hereinafter, the invention will be more specifically described by way of examples.
- Characteristics of a heat pipe were evaluated by an experimental device shown in
FIG. 2 . - First, a
glass tube 13 used as theconnection channel 5 made of borosilicate glass with an inside diameter of 2 mm and a length of 250 mm, and aglass tube 12 used as theheating unit 2 made of borosilicate glass with an inside diameter of 5 mm and a length of 150 mm were prepared, and theglass tubes glass tube 12. The wick 14 was mounted at a distance of 100 mm from the fused portion. The portion mounted with the wick 14 was used as theheating unit 2. Next, sealing by a sealingmember 11 c of which oneend 11 a is made of borosilicate glass was performed. Next, anopen end 11 b of theglass tube 13 used as the connection channel was immersed in awater bath 21, and the insides of theglass tubes fluid 20. Theheat pipe 11 of Example 1 was fixed up in this way. - Next, a
heater 22 was mounted on theheating unit 2 of theheat pipe 11 over a length L of 50 mm, and theheat pipe 11 was substantially horizontally installed. Additionally, the portion immersed in thewater bath 21 was used as the cooling unit 3 of theheat pipe 11. The temperature of coolingwater 21 a in thewater bath 21 was maintained at 0° C. Meanwhile, the amount of heat generation of theheater 22 was set to such a degree that the temperature of the heating unit was maintained at 100° C., which is the boiling point of the pure water, and theheat pipe 11 was operated. - After the
heat pipe 11 was brought into a steady state (the maximum amount of heat transport of 50 W), the surface temperature of respective units of theheat pipe 11 and the temperature of the coolingwater 21 a of thewater bath 21 were respectively measured by a thermocouple. The results are shown inFIGS. 3 and 4 . - In
FIGS. 2 to 4 , the temperature of a measurement location TC1 is the temperature of theheating unit 2, and is the surface temperature on the side of oneend 11 a of a mounting portion of theheater 22. The temperature of a measurement location TC2 is the temperature of theheating unit 2, and is the surface temperature on the side of theother end 11 b of the mounting portion of theheater 22. The temperature of a measurement location TC3 is the water temperature of the cooling water 22 a. The temperature of a measurement location TC4 is the water temperature immediately behind an outlet of theopen end 11 b. - As shown in
FIGS. 3 and 4 , it can be seen that TC1 and TC2 are maintained at about 100° C., and TC3 is maintained at about 0° C. Meanwhile, it can be seen that TC4 has a periodic peak. The maximum temperature of the peak is about 10° C., and the frequency of the peak becomes 5 Hz. Additionally, the oscillation amplitude of the workingfluid 20 is 100 mm (±50 mm) at a maximum. As such, in theheat pipe 11 of Example 1, the self-excited oscillation of the workingfluid 20 was observed in the steady state. - “Measurement of Heat Transport Rate Q and Effective Thermal Conductivity λeff”
- Next, the relationship between the heat transport rate Q (the amount of heat transport) and the effective thermal conductivity λeff in the heat pipe of Example 1 was investigated. In this experiment, the water temperature of the cooling water and the heating temperature of the heater were appropriately changed and measured. Additionally, the heat transport rate Q and the effective thermal conductivity λeff were calculated according to the following Expressions (1) and (2). The results are shown in
FIG. 5 . - In addition, in Expression (1), ρ is the density of the working fluid 20 (pure water), cp is the specific heat at constant pressure of the working fluid 20 (pure water), V is the enclosed amount of the working
fluid 20, and ΔT is the temperature increase of the water in the cooling unit during the time interval Δt. - Additionally, in Expression (2), LΦ2 is the length of the sum of the total length of the connection channel and ½ of the total length of the heating unit, TH is the temperature of the heating unit, TL is the water temperature of the cooling water in the water bath, and dΦ2 is the inside diameter of the connection channel.
-
- Next, a heat pipe of Example 2 was fixed up similarly to Example 1 except that quartz glass was used as the material for a heating-side pipe and a cooling-side pipe. Then, similarly to Example 1, the relationship between the heat transport rate Q and the effective thermal conductivity λeff in the heat pipe of Example 1 was investigated. The results are shown in
FIG. 5 . - Next, a heat pipe of Comparative Example 1 was fixed up similarly to Example 1 except that quartz glass was used as the material for a heating-side pipe and a cooling-side pipe, and the wick was not installed. Then, similarly to Example 1, the relationship between the heat transport rate Q and the effective thermal conductivity λeff in the heat pipe of Comparative Example 1 was investigated. The results are shown in
FIG. 5 . - Next, a glass tube made of quartz glass with an inside diameter of 5 mm and a length of 400 mm was prepared, and a wick made of a copper net was mounted on the inner wall surface of a hollow portion of this glass tube. Next, one end of the pipe was sealed by a sealing member. Then, the hollow portion was filled with the working fluid 20 (pure water). The
heat pipe 11 of Comparative Example 2 was fixed up in this way. - Then, similarly to Example 1, the relationship between the heat transport rate Q and the effective thermal conductivity λeff in the heat pipe of Comparative Example 2 was investigated. The results are shown in
FIG. 5 . - Next, a heat pipe of Comparative Example 3 was fixed up similarly to Comparative Example 2 except that a wick was not installed. Then, similarly to Example 1, the relationship between the heat transport rate Q and the effective thermal conductivity λeff in the heat pipe of Comparative Example 3 was investigated. The results are shown in
FIG. 5 . - (Evaluation)
- As shown in
FIG. 5 , in the heat pipe ofEmbodiment 1, it can be seen that the heat transport rate shows 33 W at a maximum, and the effective thermal conductivity λeff shows 36000 W/(m·K) at a maximum. Additionally, the heat pipe of Example 2 shows comparable effective thermal conductivity λeff at the same heat transport rate as Example 1. - On the other hand, in the heat pipes of Comparative Examples 1 to 3, it can be seen that the heat transport rate becomes equal to or less than 10 W at a maximum, the effective thermal conductivity λeff becomes about 100 W/(m·K) at a maximum, and the heat transport rate Q and the effective thermal conductivity λeff significantly decline compared to Examples 1 to 2.
- It can be seen from the results of Examples 1 to 2 that a self-excited oscillating flow heat pipe can be configured by joining two pipes with different inside diameters together, and enclosing a working fluid in the hollow portion of a pipe, and a self-excited oscillation can be developed even when this heat pipe is horizontally installed. In a case where two pipes with different inside diameters are joined together to faun a heat pipe (Examples 1 and 2), it can be seen that the heat transport rate and the effective thermal conductivity λeff are well-correlated, and increases linearly. Additionally, in Example 1, the effective thermal conductivity was increased to about 40000 W/(m·K) at a maximum. It can be seen that the effective thermal conductivity increases to 100 times the thermal conductivity of copper (400 W/(m·K)), whose thermal conductivity is comparatively high.
- Additionally, as shown in
FIGS. 3 and 4 , it can be seen that the temperature (TC1, TC2) of the heating unit is maintained near the boiling point of the working fluid (pure water). Since pure water was used this time, the temperature of the heating unit became about 100° C. However, if a suitable working fluid is selected according to the allowable temperature of the object to be cooled, efficient heat conduction can be realized. - In addition, in the above Example 1, the maximum value of the effective thermal conductivity was about 40000 W/(m·K), and the maximum value of the heat transport rate was about 50 W. However, these values are not limit values, and superior results may be obtained depending on the change of experimental conditions.
-
FIG. 6 is a comparison chart of experimental values of heat transport characteristics of the heat pipe of Example 1, and theoretical values of heat transport characteristics of the heat pipe (dream pipe) of the conventional technique, and shows the relationship between the heat transport rate Q and the effective thermal conductivity λeff regarding individual heat pipes. - The heat pipe of this conventional technique is a heat pipe (dream pipe) of a type in which heat is axially transported by forcibly oscillating a liquid within the pipe. The effective thermal conductivity λeff of the dream pipe was calculated from the following Expressions (3) and (4).
-
- Here, λ is the thermal conductivity of a fluid, Pr is the Prandt1 number, r is the tube inside diameter, ν is the kinematic viscosity of water, f is the number of oscillations, and S is oscillation amplitude. The dream pipe of this conventional technique is of a single diameter tube-type which does not have the
connection channel 5 with a smaller diameter than that of theheating unit 2. - As shown in
FIG. 6 , the effective thermal conductivity of the heat pipe of Example 1 is as large as about 10 times the dream pipe of the conventional technique. One of the factors of this effect is considered to be that, in the heat pipe of Example 1, the working fluid M in theglass tube 13 is replaced with a low-temperature liquid in thewater bath 21 whenever the working fluid M oscillates, because theopen end 11 b of theglass tube 13 is opened into a water bath. - According to the self-excited oscillating flow heat pipe of the invention, it is possible to provide a self-excited oscillating flow heat pipe capable of exhibiting high heat transport performance even if the heat pipe is horizontally installed, without making a tube meander.
Claims (4)
1. A self-excited oscillating flow heat pipe comprising:
a heating unit having a wick therein;
a cooling unit filled with a working fluid;
a connection channel which rectilinearly connects the heating unit with the cooling unit, and has a smaller channel cross-sectional area than the channel cross-sectional area of the heating unit;
a liquid plug protruding into the connection channel from the cooling unit and containing the working fluid; and
a vapor plug in the heating unit containing the vaporized working fluid,
wherein the liquid plug oscillates self-excitedly in the connection channel.
2. The self-excited oscillating flow heat pipe according to claim 1 ,
wherein the working fluid filled in the cooling unit has a free liquid level which is not bound to internal pressure.
3. The self-excited oscillating flow heat pipe according to claim 1 ,
wherein the cooling unit has an opening, and the opening is provided with an adjustment unit which adjusts the internal volume of the cooling unit.
4. The self-excited oscillating flow heat pipe according to claim 1 ,
wherein the ratio of the cross-sectional area of the heating unit and the cross-sectional area of the connection channel is from 10:1 to 2:1.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP2008029713 | 2008-02-08 | ||
JP2008-029713 | 2008-02-08 | ||
PCT/JP2009/051773 WO2009099057A1 (en) | 2008-02-08 | 2009-02-03 | Self-oscillating heat pipe |
Publications (1)
Publication Number | Publication Date |
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US20100319884A1 true US20100319884A1 (en) | 2010-12-23 |
Family
ID=40952132
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US12/866,550 Abandoned US20100319884A1 (en) | 2008-02-08 | 2009-02-03 | Self-excited oscillating flow heat pipe |
Country Status (4)
Country | Link |
---|---|
US (1) | US20100319884A1 (en) |
JP (1) | JP5403617B2 (en) |
CN (1) | CN101939611B (en) |
WO (1) | WO2009099057A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
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CN105423790A (en) * | 2015-12-04 | 2016-03-23 | 王轶珂 | Heat absorption and dissipation device |
US9482111B2 (en) | 2012-12-14 | 2016-11-01 | United Technologies Corporation | Fan containment case with thermally conforming liner |
JP2016200293A (en) * | 2015-04-07 | 2016-12-01 | 株式会社デンソー | Cooler |
US9750160B2 (en) * | 2016-01-20 | 2017-08-29 | Raytheon Company | Multi-level oscillating heat pipe implementation in an electronic circuit card module |
US20170248378A1 (en) * | 2014-08-29 | 2017-08-31 | Furukawa Electric Co., Ltd. | Planar Heat Pipe |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5942918B2 (en) * | 2013-04-23 | 2016-06-29 | 株式会社デンソー | Cooler |
JP6056633B2 (en) * | 2013-04-23 | 2017-01-11 | 株式会社デンソー | Cooler |
JP6044437B2 (en) * | 2013-04-23 | 2016-12-14 | 株式会社デンソー | Cooler |
JP6048308B2 (en) * | 2013-05-16 | 2016-12-21 | 株式会社デンソー | Cooler |
JP6176134B2 (en) * | 2014-02-03 | 2017-08-09 | 株式会社デンソー | Cooler |
JP6172060B2 (en) * | 2014-06-11 | 2017-08-02 | 株式会社デンソー | Cooler |
JP6417990B2 (en) * | 2015-02-05 | 2018-11-07 | 株式会社デンソー | Cooler |
JP6350319B2 (en) * | 2015-02-06 | 2018-07-04 | 株式会社デンソー | Cooler |
JP6390566B2 (en) * | 2015-09-22 | 2018-09-19 | 株式会社デンソー | Cooler |
Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3517730A (en) * | 1967-03-15 | 1970-06-30 | Us Navy | Controllable heat pipe |
US3621906A (en) * | 1969-09-02 | 1971-11-23 | Gen Motors Corp | Control system for heat pipes |
US3933198A (en) * | 1973-03-16 | 1976-01-20 | Hitachi, Ltd. | Heat transfer device |
US4036291A (en) * | 1974-03-16 | 1977-07-19 | Mitsubishi Denki Kabushiki Kaisha | Cooling device for electric device |
US4240189A (en) * | 1976-12-25 | 1980-12-23 | Ricoh Company, Ltd. | Method of producing heat pipe roller |
US4387762A (en) * | 1980-05-22 | 1983-06-14 | Massachusetts Institute Of Technology | Controllable heat transfer device |
US4470451A (en) * | 1981-03-16 | 1984-09-11 | Grumman Aerospace Corporation | Dual axial channel heat pipe |
US4554966A (en) * | 1983-06-02 | 1985-11-26 | Vasiliev Leonard L | Heat-transfer device |
US5566751A (en) * | 1995-05-22 | 1996-10-22 | Thermacore, Inc. | Vented vapor source |
US20030111212A1 (en) * | 2001-12-19 | 2003-06-19 | Ts Heatronics Co., Ltd. | Capillary tube heat pipe and temperature controlling apparatus |
US20030192674A1 (en) * | 2002-04-02 | 2003-10-16 | Mitsubishi Denki Kabushiki Kaisha | Heat transport device |
US20050072559A1 (en) * | 2003-03-27 | 2005-04-07 | Mitsubishi Denki Kabushiki Kaisha | Heat transport device, semiconductor apparatus using the heat transport device and extra-atmospheric mobile unit using the heat transport device |
US20060054308A1 (en) * | 2004-09-14 | 2006-03-16 | Smith Mark A | Multiple fluid heat pipe |
US20060065386A1 (en) * | 2004-08-31 | 2006-03-30 | Mohammed Alam | Self-actuating and regulating heat exchange system |
US20070196833A1 (en) * | 2005-04-21 | 2007-08-23 | Gjerde Douglas T | Open channel solid phase extraction systems and methods |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3203444B2 (en) * | 1992-12-28 | 2001-08-27 | アクトロニクス株式会社 | Non-loop type meandering thin tube heat pipe |
JP2003287378A (en) * | 2002-03-27 | 2003-10-10 | Mitsubishi Electric Corp | Capillary heat pipe and heat exchanger |
JP2003302180A (en) * | 2002-04-11 | 2003-10-24 | Furukawa Electric Co Ltd:The | Self-excited oscillation type heat pipe |
-
2009
- 2009-02-03 US US12/866,550 patent/US20100319884A1/en not_active Abandoned
- 2009-02-03 CN CN2009801044112A patent/CN101939611B/en not_active Expired - Fee Related
- 2009-02-03 WO PCT/JP2009/051773 patent/WO2009099057A1/en active Application Filing
- 2009-02-03 JP JP2009552473A patent/JP5403617B2/en not_active Expired - Fee Related
Patent Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3517730A (en) * | 1967-03-15 | 1970-06-30 | Us Navy | Controllable heat pipe |
US3621906A (en) * | 1969-09-02 | 1971-11-23 | Gen Motors Corp | Control system for heat pipes |
US3933198A (en) * | 1973-03-16 | 1976-01-20 | Hitachi, Ltd. | Heat transfer device |
US4036291A (en) * | 1974-03-16 | 1977-07-19 | Mitsubishi Denki Kabushiki Kaisha | Cooling device for electric device |
US4240189A (en) * | 1976-12-25 | 1980-12-23 | Ricoh Company, Ltd. | Method of producing heat pipe roller |
US4387762A (en) * | 1980-05-22 | 1983-06-14 | Massachusetts Institute Of Technology | Controllable heat transfer device |
US4470451A (en) * | 1981-03-16 | 1984-09-11 | Grumman Aerospace Corporation | Dual axial channel heat pipe |
US4554966A (en) * | 1983-06-02 | 1985-11-26 | Vasiliev Leonard L | Heat-transfer device |
US5566751A (en) * | 1995-05-22 | 1996-10-22 | Thermacore, Inc. | Vented vapor source |
US20030111212A1 (en) * | 2001-12-19 | 2003-06-19 | Ts Heatronics Co., Ltd. | Capillary tube heat pipe and temperature controlling apparatus |
US20030192674A1 (en) * | 2002-04-02 | 2003-10-16 | Mitsubishi Denki Kabushiki Kaisha | Heat transport device |
US20050072559A1 (en) * | 2003-03-27 | 2005-04-07 | Mitsubishi Denki Kabushiki Kaisha | Heat transport device, semiconductor apparatus using the heat transport device and extra-atmospheric mobile unit using the heat transport device |
US20060065386A1 (en) * | 2004-08-31 | 2006-03-30 | Mohammed Alam | Self-actuating and regulating heat exchange system |
US20060054308A1 (en) * | 2004-09-14 | 2006-03-16 | Smith Mark A | Multiple fluid heat pipe |
US20070196833A1 (en) * | 2005-04-21 | 2007-08-23 | Gjerde Douglas T | Open channel solid phase extraction systems and methods |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9482111B2 (en) | 2012-12-14 | 2016-11-01 | United Technologies Corporation | Fan containment case with thermally conforming liner |
US20170248378A1 (en) * | 2014-08-29 | 2017-08-31 | Furukawa Electric Co., Ltd. | Planar Heat Pipe |
US10119770B2 (en) * | 2014-08-29 | 2018-11-06 | Furukawa Electric Co., Ltd. | Planar heat pipe |
JP2016200293A (en) * | 2015-04-07 | 2016-12-01 | 株式会社デンソー | Cooler |
CN105423790A (en) * | 2015-12-04 | 2016-03-23 | 王轶珂 | Heat absorption and dissipation device |
US9750160B2 (en) * | 2016-01-20 | 2017-08-29 | Raytheon Company | Multi-level oscillating heat pipe implementation in an electronic circuit card module |
Also Published As
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---|---|
JP5403617B2 (en) | 2014-01-29 |
WO2009099057A1 (en) | 2009-08-13 |
CN101939611A (en) | 2011-01-05 |
CN101939611B (en) | 2012-05-30 |
JPWO2009099057A1 (en) | 2011-05-26 |
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