JP2022101191A - Porous tube, evaporator and cooling device - Google Patents

Abstract

To provide a porous tube which is improved in a capillary force with respect to a liquefied fluid, and increased in a flow rate for scooping up the liquefied fluid, an evaporator having the porous tube, and a cooling device having the evaporator.SOLUTION: A porous tube related to one embodiment of this disclosure comprises a tubular main body part, a plurality of groove parts extending along a center axial direction of the main body part, and arranged with intervals in a peripheral direction of the main body part are formed at an external peripheral part of the main body part, and the main body part includes a plurality of fibers with resins as main components, and a porous structure having a plurality of nodes which are connected by the fibers. A bubble point of the porous structure using an isopropyl alcohol exceeds 15kPa, and the porosity of the porous structure is 60 vol% or higher.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to perforated tubes, evaporators and cooling devices.

As a device for cooling various heating elements such as computer parts such as a central processing unit (CPU), a cooling device provided with a loop type heat pipe is used.

This cooling device includes an evaporator that vaporizes a liquid fluid with heat from a heating element to form a gaseous fluid, a condenser that condenses the vaporized fluid by cooling, and these evaporators and condensers. It is provided with a plurality of pipes that connect the two in a loop. In this cooling device, the gaseous fluid generated in the evaporator is sent to the condenser through one of the plurality of pipes, and the liquid fluid generated in the condenser is sent to the condenser in the plurality of pipes. It is sent to the evaporator through other pipes. The evaporator takes heat from the heating element as heat of vaporization of the liquid fluid and also serves as a pump for driving the circulation of the fluid.

As an evaporator of this type of cooling device, a resin porous tube (porous tube) and a metal container for accommodating the porous tube are provided, one end of the porous tube is sealed, and the other end is sealed. Opened, the average pore radius of the porous tube is 5 μm, the porosity is 35%, and it extends to the outer peripheral portion of the porous tube along the central axis direction of the porous tube and is spaced in the circumferential direction. An evaporator in which a plurality of grooves arranged in a gap are formed has been proposed (see Non-Patent Document 1).

In this evaporator, the hydraulic fluid (liquid fluid) sent into the porous tube is guided to the outside by the capillary force of the porous tube, and is guided to the outside in the plurality of grooves. The fluid is configured to phase change into a gaseous fluid by evaporating with the heat of the heating element transmitted through the container. The perforated tube as described above is also called a wick.

Hiroki Uchida, "Cooling Performance of Root Heat Pipe with Evaporators with Multiple Cylindrical Wickes Arranged in Parallel", Proceedings of the Japan Thermal Science Society (Thermal Sciences & Engineering), Japan Heat Transfer Society, August 2015 5th, Volume 23, Issue 3, p41-56

It is hard to say that the capillary force is sufficient in the perforated tube as described in the above non-patent document. When the capillary force of the porous tube is small, the force of sucking up the liquid fluid in the porous tube becomes small. If this suction force is small, the driving pressure of the liquid fluid in the loop system of the loop type heat pipe will be reduced accordingly, so that when there is a height difference in the system or when driving the liquid fluid, Stable circulation may not be obtained when acceleration is applied. Further, when the suction force becomes small, the pressure loss of the piping in the system becomes large, and it becomes difficult to send the liquid over a relatively long distance. It may be difficult to design a layout that keeps the distance apart. That is, the degree of freedom in layout design may decrease.

In addition, in the porous tube as described in the above non-patent document, the amount (flow rate) of sucking up the liquid fluid is small due to the small porosity, and therefore, the liquid state in the plurality of grooves of the porous tube. Since the amount of fluid evaporation is small, it is difficult to say that the evaporation efficiency of the liquid fluid in the evaporator is sufficient. Further, if the amount of evaporation is small, not only the amount of heat exchange with the heating element decreases, but also the transport capacity of the fluid (ability to circulate the fluid) due to the increase in the internal pressure due to evaporation also decreases, so such evaporation. It is hard to say that the cooling efficiency of the cooling device equipped with the device is sufficient. In particular, since the amount of heat generated from a heating element has increased in recent years, there is a demand for a porous tube to further improve the capillary force and an increase in the flow rate at which the porous tube sucks up a liquid fluid.

Therefore, it is an object of the present invention to provide a porous tube having an improved capillary force against a liquid fluid and an increased flow rate for sucking up the liquid fluid, an evaporator equipped with the porous tube, and a cooling device provided with the evaporator. And.

The porous tube according to one aspect of the present disclosure, which has been made to solve the above problems, includes a tubular main body portion, extends to the outer peripheral portion of the main body portion along the central axis direction of the main body portion, and has the main body portion. A plurality of grooves are formed at intervals in the circumferential direction of the portions, and the main body portion has a porous structure having a plurality of fibers mainly composed of a resin and a plurality of knots connected to each other by these fibers. The bubble point using the isopropyl alcohol having the porous structure is more than 15 kPa, and the porosity of the porous structure is 60% by volume or more.

The evaporator according to another aspect of the present disclosure made to solve the above problems is an evaporator that evaporates a liquid fluid by contact with a heating element to generate a gaseous fluid, and is described above. The perforated tube is provided with a metal container that houses the perforated tube and has an inner surface that contacts the outer peripheral portion of the main body portion, and the liquid fluid is sent from the outside of the container into the perforated tube. It is configured so that the gaseous fluid is sent to the outside of the container from the plurality of grooves of the porous tube.

The cooling device according to another aspect of the present disclosure made to solve the above problems is a cooling device that cools the heating element by contact with the heating element, and the above-mentioned evaporator and the above-mentioned evaporator are used. A condenser that condenses the generated gaseous fluid to generate a liquid fluid, and is connected to the evaporator and the condenser, and the gaseous fluid is connected to the condenser from the plurality of grooves of the evaporator. A first pipe for sending the liquid fluid from the condenser to the perforated tube, which is connected to the evaporator and the condenser, and includes the evaporator, the above. The condenser, the first pipe, and the second pipe form a circulation path for the fluid.

According to the present disclosure, there are provided a porous tube having an improved capillary force against a liquid fluid and an increased flow rate for sucking up the liquid fluid, an evaporator having the porous tube, and a cooling device having the evaporator. Will be done.

FIG. 1 is a schematic perspective view showing a porous tube of one embodiment. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a schematic enlarged view showing a part of the main body of FIG. 2 in an enlarged manner. FIG. 4 is a cross-sectional view taken along the line BB of FIG. FIG. 5 is a schematic plan view of a cooling device including an evaporator including the porous tube of the present embodiment. FIG. 6 is a cross-sectional view taken along the line CC of FIG. FIG. 7 is a cross-sectional view taken along the line DD of FIG.

[Explanation of Embodiments of the present disclosure]
The perforated tube according to one aspect of the present disclosure includes a tubular main body portion, extends to the outer peripheral portion of the main body portion along the central axis direction of the main body portion, and is spaced apart in the circumferential direction of the main body portion. A plurality of grooves to be arranged are formed, and the main body portion contains a plurality of fibers mainly composed of a resin and a porous structure having a plurality of knots connected to each other by these fibers, and the isopropyl alcohol having the porous structure is contained. The bubble point used is more than 15 kPa, and the porosity of the porous structure is 60% by volume or more.

The porous tube has the above-mentioned porous structure, and the bubble point using the isopropyl alcohol of the above-mentioned porous structure is within the above-mentioned range, so that the pore size of the above-mentioned porous structure is small, whereby the inside of the porous tube becomes liquid. The capillary force in each hole (suction path (pass) of each liquid) of the perforated tube when the fluid is supplied is improved. Further, since the porosity of the porous structure is within the above range, the abundance ratio of the porous having the capillary force is large, so that the flow rate of the liquid fluid sucked up by the main body of the entire porous tube is increased. There is. As described above, in the perforated tube, the capillary force against the liquid fluid is improved, and the flow rate at which the liquid fluid is sucked up is increased.

It is preferable that the resin is polytetrafluoroethylene and the heat of fusion of the resin is 20 J / g or less.

Since polytetrafluoroethylene (PTFE) is a fluororesin having excellent chemical resistance and solvent resistance, the fact that the above resin is PTFE makes it possible to select the type of liquid fluid supplied to the porous tube. improves. Further, since PTFE is also a non-adhesive fluororesin, the fact that the resin is PTFE can reduce the adhesion of the fluid to the main body. Therefore, by reducing the adhesion of the fluid to the main body portion in this way, for example, when the porous tube is applied to an evaporator, the amount of wasteful fluid that does not participate in evaporation can be reduced. In addition, when the amount of heat of fusion of the resin is within the above range, the bubble point using the isopropyl alcohol having the porous structure can be more reliably increased (the pore diameter of the porous structure can be reduced), and therefore the porous tube can be reduced. The above-mentioned capillary force is more reliably improved.

The perforated tube further includes a sealing portion for sealing the first end portion of the main body portion, which is one end portion in the central axial direction, and is the other end portion of the main body portion in the central axial direction. It is preferable that the two ends are open.

The perforated tube further includes a sealing portion for sealing the first end portion of the main body portion, and the second end portion of the main body portion is open, so that the liquid supplied from the second end portion is provided. The fluid can be sucked up by the main body while being stored in the main body. Therefore, the flow rate of the liquid fluid sucked up by the main body can be further increased.

It is preferable that the main body portion has a region on the second end portion side of the outer peripheral portion where the plurality of groove portions are not formed.

Since the outer peripheral portion has a region on the second end side where the plurality of grooves are not formed, when the perforated tube is housed in another device or member and used, the said perimeter is on the second end side. In sealing between the outer peripheral portion of the porous tube and the above-mentioned device or member, the adhesion (sealing property) thereof can be enhanced. Therefore, when the perforated tube has a region in which the plurality of grooves are not formed, the superiority of the perforated tube is improved.

The evaporator according to another aspect of the present disclosure is an evaporator that evaporates a liquid fluid by contact with a heating element to generate a gaseous fluid, and the above-mentioned porous tube and the above-mentioned porous tube are used. A metal container for accommodating and having an inner surface in contact with the outer peripheral portion of the main body portion, the liquid fluid is sent from the outside of the container into the porous tube, and the plurality of the porous tubes. The gaseous fluid is configured to be sent from the groove of the container to the outside of the container.

According to the evaporator, the liquid fluid sent into the porous tube described above can be sucked up to the outside of the porous tube by the capillary force of the porous tube. Then, the liquid fluid sucked up in the plurality of grooves is evaporated by the heat of the heating element via the container to change the phase into a gaseous fluid, and the obtained gaseous fluid is converted into a gaseous fluid. The increase in internal pressure due to evaporation can be used as a driving force to guide the outside of the container by the plurality of grooves. Therefore, as described above, the evaporator is provided with the porous tube having improved capillary force and an increased suction flow rate, thereby improving the evaporation efficiency.

The cooling device according to another aspect of the present disclosure is a cooling device that cools the heating element by contact with the heating element, and condenses the above-mentioned evaporator and the gaseous liquid generated by the above-mentioned evaporator. A condenser for generating a liquid fluid, a first pipe connected to the evaporator and the condenser, and a first pipe for sending the gaseous fluid from the plurality of grooves of the evaporator to the condenser. The evaporator, the condenser, the first pipe, and the second pipe connected to the evaporator and the second pipe for sending the liquid fluid from the condenser into the porous tube are provided. The second pipe forms a circulation path for the fluid.

According to the cooling device, the liquid fluid sent from the condenser is evaporated by the evaporator by the heat of the heating element, sent to the evaporator as a gaseous fluid, and sent from the evaporator. The gaseous fluid can be condensed by the condenser and sent to the evaporator as a liquid fluid. Further, the fluid can be circulated between the evaporator and the condenser by using the increase in the internal pressure due to the evaporation as a driving force. Therefore, the cooling device is provided with the evaporator whose evaporation efficiency is improved as described above, so that the cooling efficiency is improved.

Here, the "main component" is a component having the largest content, and means, for example, a component having a content of 50% by mass or more. "Bubble point with isopropyl alcohol" means a value measured in accordance with JIS-K3832 (1990) using isopropyl alcohol, which is the minimum required to extrude a liquid through the porous structure of the main body. It indicates the pressure and is an index corresponding to the maximum pore diameter of the porous structure. "Porosity" means the ratio of the total volume of the pores to the volume of the body of the porous tube.

Hereinafter, "isopropyl alcohol" may be referred to as "IPA", "bubble point" may be referred to as "BP", and "bobble point using isopropyl alcohol" may be referred to as "IPA-BP".

[Details of Embodiments of the present disclosure]
Hereinafter, embodiments of the perforated tube, the evaporator, and the cooling device according to the present disclosure will be described in detail with reference to the drawings.

[Perforated tube]
Hereinafter, in the present embodiment, the porous tube used for the evaporator will be described by way of example, but the use of the porous tube is not particularly limited to the present embodiment.

As shown in FIGS. 1 to 4, the porous tube 1 of the present embodiment includes a tubular main body 3. A plurality of groove portions 11 extending along the central axial direction (corresponding to the longitudinal direction) of the main body portion 3 and arranged at intervals in the circumferential direction are formed on the outer peripheral portion 9 of the main body portion 3. .. The main body 3 includes a plurality of fibers 17 containing a resin as a main component, and a porous structure 15 having a plurality of nodules 19 connected to each other by these fibers 17. The IPA-BP of the porous structure 15 is more than 15 kPa. The porosity of the porous structure 15 is 60% or more. The perforated tube 11 of the present embodiment further includes a sealing portion 21 for sealing the first end portion 5, which is one end portion of the main body portion 3 in the central axis direction, and the central shaft of the main body portion 3. The second end 7, which is the other end in the direction, is open.

The perforated tube 1 can suck up the liquid fluid sent into the main body 3 through the opening of the second end 7 from the inside to the outside of the main body 3. In the present embodiment, since the porous tube 1 includes the sealing portion 21, when a liquid fluid is sent into the main body portion 3, the sealing portion 21 stops the flow of the liquid fluid, and the liquid fluid is stopped. Fluid stays in the main body 3. When the amount of retention becomes large, the liquid fluid fills the inside of the main body 3. The liquid fluid in the main body 3 is sucked up from the inside to the outside by the capillary force of the porous structure 15.

As described above, the perforated tube 1 further includes a sealing portion 21 for sealing the first end portion 5, and the second end portion 7 of the main body portion 3 is open, so that the liquid supplied from the second end portion 7 is provided. The fluid can be sucked up by the main body 3 while being stored in the main body 3. Therefore, the flow rate of the liquid fluid sucked up by the main body 3 can be further increased.

When the porous tube 1 is used in an evaporator as described later, when a liquid fluid is sent from the outside of the evaporator into the main body 3 of the porous tube 1, the liquid fluid becomes the main body as described above. It is sucked up from the inside to the outside of the main body portion 3 by the capillary force of the porous structure 15 of the portion 3. The liquid fluid sucked up to the outside evaporates in the plurality of grooves 11 due to external heat (heat of the heating element as described later) and undergoes a phase change to a gaseous fluid, which is generated by this phase change. The gaseous fluid is guided in the plurality of grooves 11 by using the increase in the internal pressure generated by evaporation as a driving force, and is sent to the outside of the evaporator.

(Main body)
As shown in FIG. 3, the main body portion 3 includes a plurality of fibers 17 containing a resin as a main component, and a porous structure 15 having a plurality of knots 19 connected to each other by these fibers 17. The porous structure 15 is a fine porous structure.

The lower limit of IPA-BP of the porous structure 15 is more than 15 kPa, preferably 20 kPa, more preferably 30 kPa, further preferably 40 kPa, further preferably 60 kPa, even more preferably 80 kPa, and particularly preferably 95 kPa. As described above, this IPA-BP is an index of the pore size of the porous structure 15. That is, the smaller the IPA-BP, the larger the pore diameter of the porous structure 15, and the larger the IPA-BP, the smaller the pore diameter of the porous structure 15. The upper limit of IPA-BP of the porous structure 15 is preferably 400 kPa, more preferably 200 kPa.

If the IPA-BP does not reach the lower limit, the pore size of the porous structure 15 may be too large, and as a result, the capillary force for sucking up the liquid fluid may become too small, or the liquid liquid may not be sucked up in the first place. be. On the other hand, when the IPA-BP exceeds the upper limit, the pore diameter is too small, and as a result, the pressure loss when the liquid fluid passes through the pores becomes too large, and the flow rate at which the liquid fluid is sucked up becomes too small. There is a risk. When the porous tube 1 having such a capillary force and the flow rate too small is used for an evaporator, for example, the amount of liquid fluid (to be evaporated) in the plurality of grooves 11 of the porous tube 1 is small. Therefore, the amount of evaporation (heat exchange amount) becomes small, and the discharge capacity of the gaseous fluid driven by evaporation also becomes small. As a result, the evaporation efficiency may decrease. In addition, the cooling efficiency of the cooling device provided with this evaporator may decrease.

The IPA-BP is obtained from the measurement result by the bubble point method (BP method) specified in JIS-K3832 (1990). Specifically, by submerging the main body 3 of the porous tube 1 in the IPA by the BP method, the inside of the porous structure 15 of the main body 3 is filled with IPA, and in this state, the inside of the main body 3 is filled. The pressure at which bubbling occurs on the outside of the main body 3 when air is sent to the body 3 is measured, and the obtained pressure is determined as IPA-BP. The pressure at which bubbling occurs is determined as follows. That is, when the pressure (internal pressure) of the air applied from the inside of the main body 3 is gradually increased while the main body 3 is submerged in the IPA as described above, the pressure when the bubbles first come out is the pressure. Determine the pressure at which bubbling occurs. In this measuring method, the larger the IPA-BP, the smaller the maximum pore diameter of the main body 3 (the porous structure 15).

The lower limit of the porosity of the porous structure 15 is 60% by volume, preferably 65% by volume, more preferably 70% by volume, still more preferably 80% by volume. When the porosity is less than the above lower limit, the region where the capillary force can be generated (the region where the liquid fluid can be sucked up) in the porous tube 1 is too small, and as a result, the same IPA-BP is compared. Therefore, the amount of sucking up the liquid fluid may be too small. When the porous tube 1 whose suction amount of the liquid fluid is too small is used for an evaporator, for example, the liquid (which should be evaporated) in the plurality of grooves 11 of the porous tube 1 as described above. Since the amount of the fluid in the form is too small, the amount of evaporation (heat exchange amount) becomes small, and further, the discharge capacity of the gaseous fluid driven by evaporation also becomes small. As a result, the evaporation efficiency may decrease. In addition, the cooling efficiency of the cooling device provided with this evaporator may decrease.

On the other hand, as the upper limit of the porosity of the porous structure 15, 90% by volume is preferable, 85% by volume is more preferable, and 80% by volume is further preferable. If the porosity exceeds the upper limit, the number of pores may be too large and the strength of the porous tube 1 may decrease.

The porosity can be calculated by the following formula (1) from the dry weight E and the volume B of the main body 3 and the true specific density C of the forming material of the main body 3. The true relative density C is calculated by adding the true specific densities of each forming material of the main body 3 according to the compounding ratio. When the forming material of the main body portion 3 is PTFE (the content of PTFE is 100% by mass), the true specific gravity C of the main body portion 3 is the true specific gravity of PTFE (2.17 g / cm ³ ).
Porosity [%] = (Volume B-Dry weight E / True density C) / Volume B ... (1)

The volume B including the porous (pore) portion of the main body portion is obtained from the underwater mass D, which is the mass when the main body portion 3 is submerged in water, and the dry weight E by the following formula (2). Specifically, the dry mass E is measured by measuring the main body 3 in the air at 25 ° C. with an electronic balance. On the other hand, since the main body 3 which is a resin-made porous body such as PTFE floats on water, the mass D in water is measured by using a known method as described below while preventing the main body 3 from floating. That is, for the weight in water, a water tank (beaker, etc.) containing pure water is installed instead of the weighing pan of the electronic balance, the temperature of the pure water is set to 25 ° C., and a sample (sample) is placed in the pure water in this water tank. The measurement is performed using a jig configured so that the mass of the sample can be measured while preventing the main body 3) from floating when submerged. In this measurement of the mass D in water, unlike the measurement of IPA-BP described above, the sample is submerged in pure water so that air is present in the pores of the sample. In the measurement of the underwater mass D and the dry mass E by the electronic balance, the significant figures of the measured values shall be 4 digits or more.
Volume B [cm ³ ] = (dry mass E [g] -weight in water D [g]) / density of water [g / cm ³ ] ... (2)
Here, the specific gravity of water is 1 g / cm ³ .

As the electronic balance, a Shimadzu analytical balance (AUW-D / AUW / AUX / AUY series) manufactured by Shimadzu Corporation can be used. As the jig, the simple specific gravity measurement kit (SMK-401 / SMK-301) for the Shimadzu analytical balance manufactured by Shimadzu Corporation can be used while selecting a measuring dish for a floating sample. When such a measuring dish for a floating sample is used, the underwater mass D is detected as a negative value.

It is preferable that the capillary force of the main body portion 3 due to the porous structure 15 is large. From this viewpoint, as the lower limit of the capillary force, 6 kPa is preferable, 10 kPa is more preferable, 20 kPa is further preferable, and 30 kPa is particularly preferable. On the other hand, from the viewpoint that the capillary force should not be unnecessarily large, the upper limit of the capillary force is preferably 400 kPa, more preferably 200 kPa, and even more preferably 100 kPa. The capillary force is calculated by the following formula (3) from the maximum pore diameter F of the porous structure 15, the surface tension G of the liquid fluid to be used, and the constant c (c = 2860). 1 dyne is ^10-5 N, and 1 μm is 10 ^-4 cm.
Capillary force [kPa] = c × surface tension G [dynes / cm] / maximum pore diameter F [μm] / 1000 ... (3)
Here, the maximum hole diameter F is calculated by the following equation (4). When the liquid fluid is IPA, its surface tension G'is 20.58 days / cm.
Maximum pore diameter F [μm] = c × (IPA surface tension G') / (IPA-BP [Pa]) ... (4)

The main body portion 3 having the porous structure 15 contains a resin as a main component. The resin is not particularly limited and may be appropriately set. For example, the smaller the molecular weight of the resin, the larger the IPA-BP (that is, the smaller the pore diameter) tends to be. On the other hand, the larger the molecular weight of the resin, the smaller the IPA-BP (that is, the larger the pore diameter) tends to be. As described above, the molecular weight of the resin correlates with the heat of fusion of the resin material. That is, the larger the molecular weight of the resin, the more difficult it is for the resin to crystallize, so that the amount of heat of fusion of the resin tends to be small. On the other hand, the smaller the molecular weight of the resin, the easier it is for the resin to crystallize, so that the amount of heat of fusion of the resin tends to be large. Therefore, for example, in consideration of such a viewpoint, the heat of fusion of the resin can be appropriately set so that the IPA-BP is in a desired range.

For example, the upper limit of the heat of fusion of the resin is preferably 20 J / g, more preferably 18 J / g. As the lower limit of the heat of fusion of the resin, 10 J / g is preferable, and 15 J / g is more preferable. If the amount of heat of fusion of the resin exceeds the upper limit, the IPA-BP may become too large (the pore diameter becomes too small), and it may be difficult to suck up the liquid fluid itself as described above. On the other hand, if the heat of fusion of the resin does not reach the lower limit, the IPA-BP may become too small (the pore diameter becomes too large), and the flow rate at which the liquid fluid is sucked up may become too small as described above. be.

The heat of fusion is measured using a differential scanning calorimeter. Specifically, when the main body 3 is formed only by PTFE (the content of PTFE in the main body 3 is 100% by mass), a sample cut from the PTFE resin or the main body 3 is used as a suggestion scanning calorimeter. Add 10 g to 15 g, heat from room temperature to 245 ° C at a rate of 50 ° C / min, then heat from 245 ° C to 365 ° C at a rate of 10 ° C / min, and 365 at a rate of -10 ° C / min. The second step is to cool and hold from ° C to 350 ° C, then cool from 350 ° C to 330 ° C at a rate of -10 ° C / min, and then further cool from 330 ° C to 305 ° C at a rate of -1 ° C / min. , 296 ° C to 343 in the above third step after cooling from 305 ° C to 245 ° C at a rate of -50 ° C / min and then heating from 245 ° C to 365 ° C at a rate of 10 ° C / min. The amount of heat of fusion up to ° C. is obtained as the amount of heat of fusion of the above resin.

The larger the content of the resin in the main body 3, the easier it is to form the porous structure 15. From this viewpoint, the lower limit of the content of the resin in the main body 3 is 50% by mass, preferably 80% by mass, more preferably 90% by mass, further preferably 95% by mass, and particularly preferably 99% by mass. .. Further, the content of the resin in the main body 3 may be 100% by mass.

Examples of the resin include fluororesins. That is, the main body 3 includes a fluororesin as the main component thereof. Since the main component of the main body 3 is a fluororesin, it is possible to reduce the adhesion of the fluid to the main body 3, so that the decrease in suction efficiency and the decrease in evaporation efficiency due to this adhesion can be suppressed. Can be done. Examples of such a fluorine material include polytetrafluoroethylene (PTFE), polyfluorinated vinylidene (PVDF), tetrafluoroethylene-perfluoroalkyl-vinyl ether copolymer (PFA), and modified products thereof. Of these, PTFE and its variants (modified PTFE) are preferred. Examples of the modified PTFE include polytetrafluoroethylene copolymerized with a small amount (for example, 0.01% by mass or more and 15% by mass or less) of hexafluoropropylene (HFP), perfluoroalkyl vinyl ether (PAVE) and the like.

Of these PTFE and its variants, PTFE is preferred. Since polytetrafluoroethylene (PTFE) is a fluororesin having excellent chemical resistance and solvent resistance, the fact that the resin is PTFE makes it possible to select the type of liquid fluid supplied to the porous tube 1. improves. Further, since PTFE is also a non-adhesive fluororesin, the fact that the resin is PTFE can reduce the adhesion of the fluid to the main body 3. Therefore, by reducing the adhesion of the fluid to the main body 3 in this way, for example, when the porous tube 1 is applied to the evaporator, the amount of wasteful fluid that does not participate in evaporation can be reduced.

In addition to the above resin, the main body 3 may contain other resins and additives as long as the desired effects of the present invention are not impaired. Examples of the additives include pigments for coloring, improvement of thermal conductivity, improvement of wear resistance, prevention of low temperature flow, inorganic fillers for facilitating pore formation, metal powders, metal oxide powders, and metal sulfides. Examples include powder. The upper limit of the content of the additive in the main body 3 is preferably 40% by mass, more preferably 20% by mass.

The main body 3 is formed in a tubular shape. The cross-sectional shape of the main body 3 is not particularly limited, and examples thereof include a circular shape and an elliptical shape. FIG. 1 illustrates a mode in which the cross-sectional shape of the main body portion 3 is circular, that is, a case where the main body portion 3 is cylindrical.

The maximum inner diameter of the main body 3 is not particularly limited and may be appropriately set. For example, the lower limit of the maximum inner diameter of the main body 3 is preferably 2 mm, more preferably 5 mm. The upper limit of the maximum inner diameter of the main body 3 is preferably 40 mm, more preferably 30 mm. When the maximum inner diameter of the main body 3 is less than the above lower limit, the amount of the liquid fluid that can be contained in the main body 3 is too small, so that the liquid fluid is sufficiently supplied from the inside to the outside of the main body 3. It may be difficult to suck up. On the other hand, when the maximum inner diameter of the main body 3 exceeds the above upper limit, an excess liquid fluid is sent to the main body 3 as compared with the amount of the liquid fluid that the main body 3 can suck up. , There is a risk of waste.

The average thickness of the main body 3 (average thickness in the radial direction, wall thickness) is not particularly limited and may be appropriately set. The lower limit of the average thickness of the main body 3 is preferably 0.5 mm, more preferably 1 mm. As the upper limit of the average thickness of the main body portion 3, 5 mm is preferable, and 3 mm is more preferable. If the average thickness of the main body 3 is less than the above lower limit, the strength of the main body 3 may decrease. On the other hand, when the average thickness of the main body 3 exceeds the above upper limit, when the liquid fluid is supplied into the main body 3, the path through which the liquid fluid is sucked becomes too long, resulting in a liquid state. It may be difficult to suck up the fluid sufficiently. The average thickness of the main body 3 is an average of the measured values of the thickness at any five points.

The length of the main body 3 in the central axis direction is not particularly limited and may be appropriately set. The lower limit of the length of the main body 3 is preferably 20 mm, more preferably 40 mm. The upper limit of the length of the main body 3 is preferably 300 mm, more preferably 200 mm. When the length of the main body 3 is less than the above lower limit, the amount of the liquid fluid that can be contained in the main body 3 is too small, and the liquid fluid is transferred from the inside to the outside of the main body 3. It may be difficult to suck up sufficiently. On the other hand, when the length of the main body 3 exceeds the upper limit, the amount of the liquid fluid staying in the main body 3 becomes too large, and for example, when the porous tube 1 is applied to the evaporator, the main body 3 is used. The liquid fluid that stagnates inside may boil, which may cause it to evaporate and prevent circulation.

The plurality of groove portions 11 form a space in these grooves for phase-changing the liquid fluid sucked up from the main body portion 3 into a gaseous fluid, and form a path for guiding the gaseous fluid.

As the lower limit of the average depth (depth in the radial direction) of the plurality of groove portions 11, 10% of the average thickness (thickness) of the main body portion 3 is preferable, and 20% is more preferable. As the upper limit of the average depth of the plurality of groove portions 11, 80% of the average thickness (thickness) of the main body portion 3 is preferable, and 70% is more preferable. If the average depth of the plurality of grooves 11 is less than the above lower limit, it may be difficult to provide a space for evaporating a sufficient gaseous fluid when, for example, the porous tube 1 is applied to an evaporator. On the other hand, when the average depth of the plurality of groove portions 11 exceeds the above upper limit, the strength and rigidity of the main body portion 3 become too low, making it difficult to maintain the shape of the main body portion 3, or the main body portion 3 is destroyed. There is a risk of The "depth of the groove" means the distance between the deepest point and the outermost point in the radial direction. The average depth of the plurality of groove portions 11 is an average value of the measured values of the depths at any five points.

The lower limit of the average width (average length in the circumferential direction) of the plurality of groove portions 11 is preferably 0.5% of the average peripheral length (including the region where the groove portions are formed) of the outer peripheral surface of the main body portion 3. % Is more preferred, and 2% is even more preferred. As the upper limit of the average width of the plurality of groove portions 11, 20% of the average peripheral length of the main body portion 3 is preferable, 10% is more preferable, and 5% is further preferable. If the average width of the plurality of grooves 11 is less than the above lower limit, it may be difficult to provide a space for evaporating a sufficient gaseous fluid. In addition, it may be difficult to guide a sufficient gaseous fluid in the direction of the central axis. On the other hand, when the average width of the plurality of groove portions 11 exceeds the above upper limit, the strength and rigidity of the main body portion 3 become too low, making it difficult to maintain the shape of the main body portion 3, or the main body portion 3 is destroyed. There is a risk of The "width of the groove" means the minimum distance between the inner walls facing each other at the opening on the outermost surface in the groove 11. The average width of the plurality of groove portions 11 is an average value of the measured values of the width of the groove portions 11 at any five points. The average circumference of the main body 3 is an average value of the measured values of the circumference of the main body 3 at any five points.

In the embodiment shown in FIG. 1, a plurality of groove portions 11 are formed in parallel with the central axis direction, but the extending direction of the plurality of groove portions 11 is such that the plurality of groove portions 11 are along the central axis direction as a whole. It is not particularly limited to the direction parallel to the central axis direction. For example, the plurality of groove portions 11 may be inclined with respect to the central axis direction.

The plurality of groove portions 11 may be formed over the entire outer peripheral portion 9 of the main body portion 3 in the central axial direction, or may be formed in a part of the central axial direction. As described above, the lengths of the plurality of groove portions 11 in the central axis direction are not particularly limited and can be appropriately set. For example, the plurality of groove portions 11 may be formed in a region excluding a region in the outer peripheral portion 9 where the plurality of groove portions 11 are not formed, as will be described later.

In the embodiment shown in FIG. 1, the plurality of groove portions 11 are formed up to the edge on the first end portion 5 side of the outer peripheral portion 9 of the main body portion 3.

On the other hand, in the embodiment shown in FIG. 1, the plurality of groove portions 11 are not formed up to the edge on the second end portion 7 side of the outer peripheral portion 9 of the main body portion 3. In this aspect, the main body portion 3 has a region (hereinafter, also referred to as “non-formed region”) 15 in which the plurality of groove portions 11 are not formed on the two-end portion 7 side of the outer peripheral portion 9. The non-formed region 15 is provided over the entire circumferential direction of the outer peripheral portion 9. Since the main body portion 3 has the non-formed region 15, when the porous tube 1 is housed in another device or member (for example, an evaporator) and used, the porous tube 1 on the second end portion 7 side is used. In sealing between the outer peripheral portion 9 and the above-mentioned device or member, the adhesion (sealing property) thereof can be improved. Therefore, when the porous tube 1 has the non-formed region 15, the superiority of the porous tube 1 is improved.

The lower limit of the average length of the non-formed region 15 in the main body 3 in the central axis direction is preferably 2 mm, more preferably 3 mm. The upper limit of the average length of the non-formed region 15 in the main body 3 in the central axis direction is preferably 20 mm, more preferably 10 mm. If the length is less than the lower limit, the sealing property when the perforated tube 1 is attached to another device or member (for example, an evaporator) and used may be deteriorated. On the other hand, when the length of the main body 3 exceeds the upper limit, the region of the main body 3 that sucks up the liquid fluid (the region where the groove is formed) becomes relatively small, so that the liquid state is contained in the main body 3. When the fluid is sent, the amount of liquid fluid sucked up may be small. The average length of the non-formed region 15 in the central axis direction is an average value of measured values of the length of the non-formed region in the central axis direction at any five points in the circumferential direction.

The sealing portion 21 seals the first end portion 5 side of the main body portion 3. The material for forming the sealing portion 21 may be any material as long as it does not allow a liquid fluid to pass through, and is not particularly limited and may be appropriately set. For example, examples of the material for forming the sealing portion 21 include a material containing a resin as a main component. As such a material containing a resin as a main component, for example, a material for forming the main body portion 3 described above can be mentioned. As illustrated in FIG. 2, the sealing portion 21 may be formed on a disk, fitted into the first end portion 5 of the main body portion 3, and bonded with a known adhesive. In addition, although not shown, the sealing portion 21 may be formed by sealing the second end portion 7 of the main body portion 3 with a heat seal or the like.

(Manufacturing method of porous tube)
An example of the manufacturing method of the perforated tube 1 will be described.

The method for producing the porous tube 1 of the present embodiment is exemplified as follows, for example. That is, for example, first, a powdery material containing a resin as a main component and an additive such as an extrusion aid (an additive removed in the present manufacturing process) are mixed to form a material for forming the main body 3. After preparation, the premolding step of compression-molding this forming material into a cylindrical shape (tubular) and the premolding body which is the cylindrical compression-molded body obtained in the pre-molding step are 30 ° C. below the melting point of the resin. An extrusion step of heating to about 100 ° C. to extrude into a cylindrical shape, a drying step of heating the cylindrical extruded body obtained in the extrusion step to a temperature higher than the evaporation temperature of the extrusion aid and drying the mixture, and the above. The cylindrical dried product obtained in the drying step was stretched while being heated in a tubular furnace at 80 ° C. below the melting point of the resin and 500 ° C. above the melting point of the resin, and was obtained in the stretching step. By performing a firing step of firing a cylindrical stretch-molded body while heating it at a temperature equal to or higher than the melting point of the resin, a cylindrical stretch-cast body is obtained.

Next, while expanding the obtained stretched fired body in the radial direction or turning it upside down, the outer peripheral portion thereof is spaced along the central axis direction of the cylindrical stretched fired body and in the circumferential direction. A slit portion forming step of forming a plurality of slit portions arranged along the central axis direction and at intervals in the circumferential direction by making a notch with a knife-shaped jig, and the slit portion forming. The outer surface side of the stretched sintered body is heated to a temperature equal to or higher than the melting point by heating the outer surface of the stretched sintered body with the dimensions in the central axis direction fixed in the cylindrical stretched fired body in which the plurality of slit portions are formed in the step. By performing a contraction step of contracting between the plurality of slit portions in the circumferential direction, a cylindrical main body portion having a recess (that is, a groove portion) oriented (extending) in the central axis direction is obtained. In the present embodiment, a porous tube is produced by further performing a sealing step of sealing one end of the cylindrical main body portion obtained in the shrinking step.

In the preforming step, for example, a cylindrical preformed body is formed by compression molding a mixture of the powdery material and the additive using a known compression molding machine having a cylindrical mold. To get. The powdery material is a material for forming the main body 3 described above.

In the extrusion molding step, for example, using a known extrusion molding machine having an annular die and a core having desired dimensions according to the main body portion to be finally obtained, the cylindrical shape obtained in the preforming step. By heating the preformed body of the above resin to 30 ° C. to 100 ° C., which is lower than the melting point of the resin, and extruding the product, a cylindrical extruded body is obtained.

In the drying step, for example, using a known heating / drying machine, the cylindrical extruded body obtained in the extrusion step is heated to a temperature equal to or higher than the evaporation temperature of the extrusion aid and dried to form a cylindrical shape. Get a dry body.

In the stretching step, for example, the cylindrical dried body obtained in the drying step is sequentially bridged over two roller members arranged with a gap between them, and the cylindrical dried body is placed below the melting point of the resin. 80 ° C. to 500 ° C. above the melting point of the above resin and take up while stretching (for example, winding). In this pick-up, the rotation speed of the roller member on the downstream side in the pick-up direction is made larger than the rotation speed of the roller member on the upstream side. If the heating temperature is set to be equal to or higher than the melting point of the resin, stretching can be performed while firing. This forms a porous structure with a plurality of fibers and a plurality of nodules connected to each other by these fibers. Such a stretching step can be performed using a known stretching and firing furnace. The stretching ratio in the stretching is appropriately set so that the main body of the finally produced porous tube has the desired IPA-BP and porosity. The stretching ratio can be, for example, 2 to 8 times in the stretching direction.

In the firing step, for example, using a known firing furnace, the cylindrical stretched molded body obtained in the stretching step is fired while heating at a temperature equal to or higher than the melting point of the resin to obtain a cylindrical stretched fired body. ..

Using the stretching firing furnace, the temperatures of drying in the drying step, stretching in the stretching step, and firing in the firing step are set to the temperatures in each step, and these steps are continuously performed. You may go. When the enrollment step and the firing step are continuously performed, the firing step can be performed at the same time as the stretching step by stretching while heating to a temperature equal to or higher than the melting point of the resin.

In the slit portion forming step, for example, while expanding the cylindrical stretched fired body obtained in the firing step in the radial direction or turning it upside down while keeping the inner dimensions constant, the knife-shaped healing is performed. Using a known cutter or the like as a tool, a plurality of slit portions extending along the central axis direction and arranged at intervals in the circumferential direction are formed on the outer peripheral portion of the cylindrical stretched molded body. When forming the slit portion while inverting the inside and outside, the inner peripheral portion at the time of stretch molding is inverted to the outer peripheral portion, and the slit portion is formed on the outer peripheral portion. Due to the above-mentioned inversion, the outer peripheral portion originally located on the inner peripheral side (before the inversion) expanded in the circumferential direction by the ratio of the outer circumference / inner circumference (ratio of the outer circumference to the inner circumference) and became tense. As a result of the state, the stretched and fired body expands in the radial direction. As the cutter, for example, a cutter having a cross section of a cut portion formed in a triangular shape having a tip as an apex can be used. When a notch is formed in the outer peripheral portion by using this cutter, the shape of the notch becomes a triangular shape having an apex inside.

When the cylindrical stretched fired body is taken over, the cylindrical stretched body is stretched by adjusting the piercing depth and the piercing load for forming a notch in the cylindrical stretched fired body with the knife-shaped jig. On the outer peripheral portion of the fired body, a region in which the slit portion is formed in the central axis direction and a smooth region in which the slit portion is not formed can be formed. By repeatedly forming the cuts in the cylindrical stretch-fired body at desired intervals, a region in which a plurality of slit portions are formed in the central axis direction and a plurality of regions in which these slit portions are not formed are formed. Can be repeatedly formed with the region of. The expansion can be performed using a known diameter-expanding device, or can be performed using a known front-to-back reversing device. The degree of expansion can be appropriately set according to the dimensions, spacing, etc. of the plurality of grooves finally obtained. For example, the maximum outer diameter of the cylindrical stretched fired body is 1.5 times to 4 times. It is preferable to perform the above expansion so as to be doubled.

In the shrinkage step, for example, a known heating device is used to heat the cylindrical stretch-fired body in which the plurality of slit portions are formed to a temperature equal to or higher than the melting point of the resin. By this heating, the stretched fired body contracts in the circumferential direction, and at this time, the plurality of flat portions between the plurality of slit portions contract in the circumferential direction to form convex portions, and at the same time, between the plurality of flat portions. The wall portions of the plurality of slit portions are contracted in the circumferential direction, whereby a groove portion is formed between the plurality of convex portions. More specifically, the stretched fired body is fixed from the inside by inserting a round bar made of metal (for example, stainless steel) having an outer diameter substantially equal to the inner diameter of the stretched fired body, and thus the stretched body is thus stretched. With the inner peripheral surface side of the fired body fixed, the stretched fired body is heated to a temperature equal to or higher than the melting point of the resin using a known tube furnace. By this heating, the outer peripheral surface side can be contracted in the circumferential direction while suppressing the contraction in the central axis direction and the contraction on the inner peripheral surface side of the stretched fired body. In this way, a main body portion having a plurality of groove portions can be obtained.

In the sealing step, for example, a resin sealing body is inserted into one end of the cylindrical main body obtained in the shrinking step in the central axis direction and fixed with an adhesive or the like (not shown). In addition, although not shown, a sealed portion can be formed by heating the cylindrical main body portion by sandwiching one end portion in the central axial direction using a known heat sealing machine. In addition, for example, when there is a region where a plurality of grooves are not formed as described above on one end side (corresponding to the above-mentioned second end portion) of the outer peripheral portion of the cylindrical main body portion. , The end opposite to this end (corresponding to the first end) is sealed.

The preforming step, the extrusion step, the drying step, the stretching step, the firing step, the slit portion forming step, the shrinking step, and the sealing step consist of two or more of these plurality of steps. It can be performed continuously, and each process can also be performed separately. Further, according to the above manufacturing method, the porous tube 1 can be continuously manufactured as described above. Further, in the preformation step to the shrinkage step, a plurality of shrinkage bodies having a length corresponding to a plurality of main body portions in the central axis direction are produced, and the shrinkage bodies are cut in the central axis direction to obtain a plurality of shrinkage bodies. It is also possible to obtain a main body portion, whereby a plurality of main body portions can be continuously obtained.

As described above, in the porous tube 1 of the present embodiment, the capillary force against the liquid fluid is improved, and the flow rate at which the liquid fluid is sucked up is increased.

The use of the perforated tube 1 is not particularly limited, but it is preferably used for an evaporator that evaporates a liquid fluid.

The liquid fluid sent to the tube 1 is not particularly limited, and examples thereof include an organic solvent such as water and alcohol, a mixed solution of the water and the organic solvent, and a refrigerant used in a cooling device.

[Cooling system]
The cooling device of the present embodiment includes an evaporator including the porous tube of the present embodiment described above. As shown in FIGS. 5 to 7, the cooling device of the present embodiment includes an evaporator that evaporates a liquid fluid, a condenser that condenses the gaseous fluid evaporated by the evaporator into a liquid, and the above. It is provided with a plurality of pipes connecting the evaporator and the condenser. Such a cooling device is also called a loop type heat pipe. The fluid used in the evaporator may be referred to as a working fluid as the fluid for operating the circulation in the loop type heat pipe.

Specifically, the cooling device 30 of the present embodiment is a cooling device that cools the heating element 80 by contact with the heating element 80, and is the above-mentioned evaporator 40 having the perforated tube 1 and the above-mentioned evaporator. A condenser 50 that condenses the gaseous fluid generated in 40 to generate a liquid fluid, is connected to the evaporator 40 and the condenser 50, and is connected to the evaporator 40 and the condenser 50. A first pipe 71 for sending the gaseous fluid from the plurality of grooves 11 of the evaporator 40 to the condenser 50, and for sending the liquid fluid from the condenser 50 into the porous tube 1. The second pipe 73 is provided, and the evaporator 40, the condenser 50, the first pipe 71, and the second pipe 73 form a circulation path for the fluid. The cooling device 30 of the present embodiment further accommodates a liquid storage unit 60 having a fourth pipe 63 for accommodating the liquid fluid to be sent to the evaporator 40 and sending the contained liquid fluid to the evaporator 40. Be prepared.

<Evaporator>
As shown in FIGS. 6 and 7, the evaporator 40 is an evaporator that evaporates a liquid fluid by contact with a heating element 80 to generate a gaseous fluid, and is the same as the above-mentioned porous tube 1. A metal container 41 having an inner surface 43 that accommodates the perforated tube 1 and is in contact with the outer peripheral portion 9 of the main body portion 3 is provided from the outside of the container 41 (specifically, the fourth pipe 63 and the fourth pipe 63). The liquid fluid is sent into the perforated tube 1 (from the second pipe 73), and the plurality of grooves 11 of the perforated tube 1 are sent to the outside of the container 41 (specifically, to the first pipe 71). It is configured to send the gaseous fluid.

The evaporator 40 sucks the liquid fluid sent into the main body 3 of the porous tube 1 of the present embodiment described above to the outside of the main body 3 by the capillary force of the porous structure 15 (see FIG. 4) and sucks it up. The liquid fluid is phase-changed into a gaseous fluid by evaporating it with the heat of the heating element 80 via the container 41, and the obtained gaseous fluid is transferred to the outside of the container 41 by the plurality of grooves 11. invite.

(container)
The container 41 is made of metal. The material for forming the container 41 is not particularly limited, and examples thereof include copper and the like. The inner surface 43 of the container 41 is partially in contact with at least a part of the outer peripheral portion 9 of the main body portion 3 of the porous tube 1, and heat exchange occurs between the porous tube 1 and the container through this contact. The area where the inner surface 43 of the container 41 comes into contact with the main body 3 is not particularly limited, and the heat exchange can be appropriately set to a desired degree.

In the present embodiment, the non-formed region (region in which a plurality of groove portions 11 are not formed) 15 on the second end portion 7 side of the outer peripheral portion 9 of the porous tube 1 and the inner surface 43 of the container 41 are known. It is sealed by a sealing member (not shown). As a result, the liquid fluid sucked up from the inside of the porous tube 1 into the plurality of groove portions 11 and the gaseous fluid generated in the plurality of groove portions 11 from between these are the porous tube 1 and the fourth pipe 63. Leakage between and is suppressed.

The container 41 is formed with a first opening 45 for sending the liquid fluid into the porous tube 1 from the outside of the container 41 (specifically, from the fourth pipe 63 and the second pipe 73). The first opening 45 is formed in an annular shape, and the fourth pipe 63 of the liquid accommodating portion 60, which will be described later, is fitted into the peripheral portion of the first opening 45 so that the liquid fluid does not leak from these connecting portions. It is sealed by a known sealing member (not shown). In the present embodiment, the second pipe 73 is inserted inside the fourth pipe 63.

A gap is formed between the inner surface 43 in the container 41 and the first end portion 5 of the main body portion 3 of the porous tube 1, and this gap constitutes the gas collecting portion (manifold) 49. The gas collecting portion 49 is connected to a plurality of groove portions 11 of the main body portion 3 of the porous tube 1, and is configured so that the gaseous fluid generated in the plurality of groove portions 11 collects in the gas collecting portion 49.

The container 41 is formed with a second opening 47 for sending the gaseous fluid collected in the gas collecting portion 49 to the outside of the container 41 (specifically, to the first pipe 71). One end of the first pipe 71 is fitted into the peripheral edge of the second opening 47, and is sealed by a known sealing member (not shown) so that the gaseous fluid does not leak from these connecting portions.

(Condenser)
The condenser 50 receives heat from the gaseous fluid generated by the evaporator 40 and causes the gaseous fluid to undergo a phase change to a liquid state. The condenser 50 may be cooled as long as it can be cooled. For example, one end of the condenser 50 is connected to the first pipe 71, the other end of the condenser 50 is connected to the second pipe 73, and the third pipe 51 is cooled from the outside. A cooling unit 53 is provided. The third pipe 51 is a pipe made of metal such as copper. Examples of the cooling unit 53 include known cooling units. Examples of such a known cooling unit include a fin portion having a plurality of metal protrusions and a blower or a suction machine that brings air into contact with the fin portion.

(Liquid storage)
The liquid accommodating unit 60 is for accommodating a liquid fluid and sending the contained liquid fluid to the evaporator 40. The liquid accommodating unit 60 has a tank unit 61 for accommodating the liquid fluid, and a fourth pipe 63 for sending the liquid fluid from the tank unit 61 into the porous tube 1 in the evaporator 40. .. The fourth pipe 63 is a pipe made of metal such as copper. In the present embodiment, a known sealing member (not shown) so that the second pipe 73 penetrates through the tank portion 61 and the liquid fluid does not leak from the connecting portion between the tank portion 61 and the second pipe 73. ) Is configured to be sealed. The fourth pipe 63 is formed so that its outer diameter is smaller than the inner diameter of the main body 3 of the porous tube 1. One end of the fourth pipe 63 is connected to the evaporator 40 side of the tank portion 61, and the other end of the fourth pipe 63 is the peripheral edge of the first opening 45 of the container 41 of the evaporator 40 as described above. It is fitted in. The tip edge of the other end of the fourth pipe 63 is arranged with a gap from the sealing portion 21 of the porous tube 1. The fourth pipe 63 is formed so that its inner diameter is larger than the outer diameter of the second pipe 73, and the second pipe 73 is inserted into the fourth pipe 63 with a gap. The liquid fluid is sent from the tank portion 61 into the porous tube 1 through the gap between the fourth pipe 63 and the second pipe 73.

(1st pipe)
The first pipe 71 is a pipe made of metal such as copper. The first pipe 71 is for sending the gaseous fluid from the plurality of grooves 11 of the porous tube 1 in the evaporator 40 to the condenser 50 through the gas collecting portion 49. One end of the first pipe 71 is connected to the evaporator 40. Specifically, the one end portion of the first pipe 71 is fitted into the peripheral edge portion of the second opening 47 of the evaporator 40, and a known sealing member (to prevent the gaseous fluid from leaking from these connecting portions). (Not shown) is sealed. The other end of the first pipe 71 is connected to one end of the third pipe 51 of the condenser 50 (the end on the upstream side in the flow direction of the fluid).

(Second pipe)
The second pipe 73 is a pipe made of metal such as copper. The second pipe 73 is for sending the liquid fluid from the condenser 50 into the main body 3 of the porous tube 1 in the evaporator 40. One end of the second pipe 73 is connected to the evaporator 40 so that the liquid fluid can be sent to the evaporator 40 by being inserted into the fourth pipe 63 described above. Specifically, the one end portion of the second pipe 73 is arranged in the fourth pipe 63 described above, and a gap is provided between the main body portion 3 of the porous tube 1 and the sealing portion 21 of the porous tube 1. Will be inserted. The other end of the second pipe 73 is connected to the other end of the third pipe 51 of the condenser 50 (the end on the downstream side in the flow direction of the fluid). As described above, the liquid accommodating portion 60 is arranged between the evaporator 40 and the condenser 50 in the second pipe 73.

(Circular route)
The above-mentioned evaporator 40, condenser 50 (specifically, the third pipe 51 in the condenser 50), the first pipe 71, and the second pipe 73 form a circulation path for the fluid. The first pipe 71, the second pipe 73, and the third pipe 51 described above may be integrally formed as one pipe.

(Working fluid)
The fluid is not particularly limited as long as it undergoes a phase change from a liquid state to a gas state due to the heat generated by the heating element 80. As the fluid, for example, an alcohol such as ethanol and an organic solvent such as a non-conductive and non-flammable fluorine-based solvent (for example, fluoride polyether, hydrofluoro ether, etc.) are preferable. The boiling point of the organic solvent is preferably less than or equal to the control temperature (control temperature) of the heating element 80, for example, preferably 100 ° C. or lower, and more preferably less than 80 ° C.

(Heating element)
Examples of the heating element 80 include a supercomputer, a personal computer (personal computer), a server, a CPU of a game machine, SSD, and the like.

(Operation of cooling device)
According to the cooling device 30, the liquid fluid sent from the liquid accommodating portion 60 into the main body 3 in the porous tube 1 in the evaporator 40 via the fourth pipe 63 is transferred by the porous structure 15 of the main body 3. The liquid fluid sucked up from the inside to the outside of the main body 3 is evaporated in the plurality of grooves 11 by the heat of the heating element 80 through the container 40. Using the increase in internal pressure due to this evaporation as a driving force, the gaseous fluid generated by evaporation is guided through the plurality of grooves 11 and discharged from the container 40 to the first pipe 71, and passes through the first pipe 71. It is sent to the condenser 50. The gaseous fluid sent to the condenser 50 is cooled by the condenser 50 and undergoes a phase change to a liquid state, and the liquid fluid generated by this phase change is sent to the evaporator 40 through the second pipe 73. .. In the present embodiment, the liquid fluid is sent into the porous tube 1 from the liquid accommodating portion 60 and the condenser 50.

In this way, the heating element 80 is cooled by the fluid circulating in the evaporator 40 and the condenser 50. As described above, the driving force of this circulation is an increase in internal pressure due to evaporation of the liquid fluid. In the circulation, the liquid fluid is sent from the fourth pipe 63 and the second pipe 73 into the porous tube 1. The liquid fluid sent from the fourth pipe 63 flows out from the tip of the fourth pipe 63 and is sent to the gap between the outer peripheral portion of the fourth pipe 63 and the inner peripheral portion of the porous tube 1. The liquid fluid from the second pipe 73 flows out from the tip of the second pipe 73 and is sent to the gap between the outer peripheral portion of the fourth pipe 63 and the inner peripheral portion of the porous tube 1. The filling amount of the liquid fluid in the liquid accommodating portion 60 is set so that the liquid fluid flowing out from the tip of the second pipe 73 does not flow (backflow) into the fourth pipe 63.

Since the cooling device of the present embodiment includes the evaporator 40 including the porous tube 1 of the present embodiment described above, the cooling efficiency is improved.

[Evaporator]
The evaporator 40 of the present embodiment is the evaporator 40 provided in the cooling device 30 described above. That is, the evaporator 40 of the present embodiment is an evaporator that evaporates a liquid fluid by contact with a heating element 80 to generate a gaseous fluid, and is the above-mentioned porous tube 1 and the above-mentioned porous tube. A metal container 41 having an inner surface 43 in contact with the outer peripheral portion 9 of the main body portion 3 is provided, and the liquid fluid is sent from the outside of the container 41 into the porous tube 1. In addition, the gaseous fluid is configured to be sent from the plurality of grooves 11 of the porous tube 1 to the outside of the container 41.

Since the details of the evaporator 40 of this embodiment are as described above, the detailed description thereof will be omitted.

Since the evaporator 40 of the present embodiment includes the above-mentioned porous tube 1, the evaporation efficiency is improved.

[Other embodiments]
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is not limited to the configuration of the above embodiment, but is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. To.

For example, in the above embodiment, the embodiment in which the evaporator is provided with one porous tube has been described, but the embodiment in which the evaporator is provided with a plurality of porous tubes may be adopted.

For example, in the above embodiment, the embodiment in which the cooling device is provided with one evaporator has been described, but the embodiment in which the cooling device is provided with a plurality of evaporators may be adopted.

For example, in the above embodiment, the embodiment in which the cooling device is provided with one condenser has been described, but the embodiment in which the cooling device is provided with a plurality of condensers may be adopted.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1]
After mixing 100 parts by mass of PTFE fine powder (650J manufactured by Mitsui Chemers, heat of melting: 17.01J / g) and 22 parts by mass of naphtha as an extrusion aid, the mixture was mixed with an outer diameter of 129 mm using a compression molding machine. A cylindrical compression molded product was produced by compression molding into a cylindrical shape having an inner diameter of 25 mm.

Using an extruder with a cylinder diameter of 130 mm and a mandrel diameter of 24.8 mm, the heating temperature was set to 50 ° C., the die diameter was set to 10.5 mm, and the core diameter was set to 5.3 mm. A cylindrical extruded body was produced by extruding the compression molded body of the above into a cylindrical shape.

The obtained cylindrical extruded body was dried at 160 ° C. using a stretching firing furnace to evaporate naphtha to prepare a cylindrical dried body. Then, while heating the cylindrical dried body obtained above at a heating temperature of 380 ° C. in the stretching firing furnace, stretching is performed by stretching at a stretching ratio of 3.8 times in the central axial direction. The firing was performed at the same time, whereby a cylindrical stretched fired body was produced.

While inverting the obtained cylindrical stretch-fired body, a plurality of pieces at a constant depth are provided on the outer peripheral portion that appears on the outside by using a cutter along the central axis direction and at intervals in the circumferential direction. By making a notch, a plurality of slit portions were formed. The depth and spacing of the slit portions were set so that the depth and spacing of the finally obtained groove portions would be desired values.

The stretched fired body was fixed from the inside by inserting a stainless steel round bar having an outer diameter of 5 mm into the stretched fired body in which these slit portions were formed. By heating the stretched fired body at 700 ° C. for 5 seconds in a state where the inner peripheral surface side of the stretched fired body is fixed in this way, the outer peripheral surface side of the stretched fired body is rotated in the circumferential direction. It was shrunk to form a body with a plurality of grooves.

By cutting the obtained main body portion in the radial direction, a cylindrical main body portion having a length of 150 mm in the central axial direction, an average thickness (thickness) of 1.5 mm, and a maximum inner diameter of 5 mm was formed (Example 1). .. The average depth of the groove in the main body was set to 50% of the average thickness of the main body, and the average width of the groove was set to 3.8% of the average circumference of the main body. The amount of heat of fusion of the PTFE used was measured by the method described above. The IPA-BP, porosity, and capillary force of the obtained cylindrical main body against a fluorinated solvent (Novec 7100 manufactured by 3M, surface tension: 13.6 dyne / cm, boiling point: 61 ° C.) were measured by the above-mentioned method. .. The results are shown in Table 1. For reference, Table 1 also shows the maximum pore diameter calculated from IPA-BP by the above method. In Example 1, since the content of PTFE in the main body is 100% by mass, the amount of heat of fusion of PTFE can be regarded as the amount of heat of fusion of the main body.

[Examples 2 and 3]
A cylindrical main body of Example 2 was produced in the same manner as in Example 1 except that the draw ratio was set to 7.6 times. A cylindrical main body of Example 3 was produced in the same manner as in Example 1 except that the draw ratio was 5.5 times. For the obtained cylindrical main body, IPA-BP, porosity and capillary force were measured in the same manner as in Example 1, and the maximum pore diameter was calculated from IPA-BP. The results are shown in Table 1.

[Example 4]
A cylinder of Example 4 was used in the same manner as in Example 1 except that a PTFE (F121 manufactured by Daikin Co., Ltd., heat of fusion: 16.11 J / g) different from that of Example 1 was used and the stretching ratio was 7.6 times. For the obtained cylindrical main body, the amount of heat of melting of the PTFE used in the same manner as in Example 1, and the IPA-BP and pore ratio of the obtained cylindrical main body, And the capillary force were measured, and the maximum pore diameter was calculated from IPA-BP. The results are shown in Table 1. As in Example 1, in Example 4, since the content of PTFE in the main body is 100% by mass, the amount of heat of fusion of PTFE can be regarded as the amount of heat of fusion of the main body.

[Example 5]
A cylindrical main body of Example 5 was produced in the same manner as in Example 4 except that the draw ratio was set to 6 times, and the obtained cylindrical main body was IPA-in the same manner as in Example 1. The BP, porosity and capillary force were measured, and the maximum pore diameter was calculated from IPA-BP. The results are shown in Table 1.

[Comparative Example 1]
Using a PTFE (CD123 manufactured by AGC, heat of fusion: 21.36 J / g) different from that of Example 1, the same as that of Example 1 except that the blending amount of naphtha was 23 parts by weight and the stretching ratio was 6 times. Then, the cylindrical main body of Comparative Example 1 was produced, and for the obtained cylindrical main body, the amount of heat of fusion of the PTFE used and the obtained cylindrical main body were obtained in the same manner as in Example 1. IPA-BP, pore ratio, and capillary force were measured, and the maximum pore diameter was calculated from IPA-BP. The results are shown in Table 1. As in Example 1, in Comparative Example 4, since the content of PTFE in the main body is 100% by mass, the amount of heat of fusion of PTFE can be regarded as the amount of heat of fusion of the main body.

[Comparative Examples 2 to 4]
A cylindrical main body of Comparative Example 2 was produced in the same manner as in Comparative Example 1 except that the blending amount of naphtha was 15 parts by weight. A cylindrical main body of Comparative Example 3 was produced in the same manner as in Comparative Example 1 except that the draw ratio was 8.4 times. A cylindrical main body of Comparative Example 4 was produced in the same manner as in Comparative Example 2 except that the draw ratio was 8.4 times. For the obtained cylindrical main body, IPA-BP, porosity and capillary force were measured in the same manner as in Example 1, and the maximum pore diameter was calculated from IPA-BP. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 5 in which the IPA-BP is more than 15 kPa and the porosity is 60% by volume or more, Comparative Example 1 in which at least one of the IPA-BP and the porosity is out of the above range. It was shown that the capillary force against the liquid fluid was larger than that of -4. Further, the larger the IPA-BP, the larger the capillary force tended to be, and the larger the porosity, the larger the capillary force tended to be.

INDUSTRIAL APPLICABILITY The present invention can be suitably used for cooling a heating element such as an electric device.

1 Perforated tube 3 Main body 5 1st end 7 2nd end 9 Peripheral 11 Groove 13 Region where no groove is formed (non-formed region)
15 Porous structure 17 Fiber 19 Knot 21 Sealing part 30 Cooling device 40 Evaporator 41 Container 43 Inner surface 45 First opening 47 Second opening 49 Gas storage part 50 Condenser 51 Third piping 53 Cooling part 60 Liquid storage part 61 Tank part 63 4th pipe 71 1st pipe 73 2nd pipe 80 Heat generator

Claims (6)

Equipped with a tubular body,
A plurality of grooves extending along the central axis direction of the main body and arranged at intervals in the circumferential direction of the main body are formed on the outer peripheral portion of the main body.
The main body portion includes a plurality of fibers containing a resin as a main component and a porous structure having a plurality of nodules connected to each other by these fibers.
The bubble point using the above-mentioned porous structure isopropyl alcohol is more than 15 kPa.
A porous tube having a porosity of 60% by volume or more in the porous structure. The above resin is polytetrafluoroethylene,
The porous tube according to claim 1, wherein the heat of fusion of the resin is 20 J / g or less. Further provided with a sealing portion for sealing the first end portion, which is one end portion in the central axis direction of the main body portion, is provided.
The porous tube according to claim 1 or 2, wherein the second end portion, which is the other end portion in the central axis direction of the main body portion, is open. The porous tube according to claim 3, wherein the main body portion has a region in which the plurality of groove portions are not formed on the second end portion side of the outer peripheral portion. An evaporator that evaporates a liquid fluid by contact with a heating element to generate a gaseous fluid.
The porous tube according to any one of claims 1 to 4,
A metal container for accommodating the perforated tube and having an inner surface in contact with the outer peripheral portion of the main body portion.
An evaporator configured such that the liquid fluid is sent from the outside of the container into the porous tube, and the gaseous fluid is sent from the plurality of grooves of the porous tube to the outside of the container. A cooling device that cools the heating element by contact with the heating element.
The evaporator according to claim 5 and
A condenser that condenses the gaseous fluid generated by the above evaporator to generate a liquid fluid, and
It is connected to the evaporator and the condenser, and is connected to the evaporator and the condenser, and is connected to the first pipe for sending the gaseous fluid from the plurality of grooves of the evaporator to the condenser, and is condensed. It is equipped with a second pipe for sending the liquid fluid from the vessel into the perforated tube.
A cooling device in which a circulation path for the fluid is formed by the evaporator, the condenser, the first pipe, and the second pipe.

Images