JP7336130B2 - Refrigerant circulation cooling device - Google Patents

Description

The present invention, for example, like a heat pipe, encloses a refrigerant in a closed space, heats and vaporizes the refrigerant on the inner wall around the heat source, cools and condenses the refrigerant on the inner wall around the low-temperature part, and re-condenses it on the inner wall around the heat source. It relates to a refrigerant circulation type cooling device that cools a heat source by supplying a refrigerant to the cooling device.

In a refrigerant circulation type cooling device represented by a heat pipe, inside a closed space, the refrigerant is heated and vaporized by contact with the inner wall around the heat source, and the vaporized gas is cooled and condensed on the inner wall around the low temperature part. The refrigerant that has been liquefied again is circulated to the heat source using capillary action.

In Patent Document 1, a closed space consisting of a boiling portion where a liquid-phase working fluid receives heat from a heat source and boils and evaporates and a condensation portion where a gas-phase working fluid loses latent heat and condenses is formed in a pipe. However, when the internal pressure or internal temperature of this pipe reaches one value, the gas inside the pipe is discharged.

JP 2007-003114 A

However, especially when the heat source reaches a high temperature, the refrigerant in the sealed space rapidly vaporizes at the contact portion with the heat source, generating a large amount of bubbles. When these bubbles accumulate on the inner wall around the heat source, they form a heat-insulating layer, which prevents new liquid-phase refrigerant from coming into contact with the inner wall, resulting in deterioration of cooling efficiency.
Therefore, in such a refrigerant circulation type cooling device, it is effective to smoothly transfer the air bubbles remaining in the internal space around the heat source to the low-temperature part together with the refrigerant flow.

On the other hand, in Japanese Patent Application No. 2017-217145, the inventors utilize the self-developed precision processing technology to form fine holes in the tubular electrode filled with physiological saline in the direction of the incision progress. proposed the technique. By strictly controlling the diameter of the small hole, the physiological saline solution is directed into the tissue through the small hole only when the vapor pressure of the saline solution exceeds a predetermined pressure due to the heat generated by the tubular electrode during tissue incision. It became possible to discharge and cool the tubular electrode to a predetermined temperature or less.

Here, when the internal pressure of the small hole is less than a predetermined pressure, the ejection is limited by the surface tension and frictional force between the surface around the hole and the physiological saline. On the other hand, due to the expansion of the saline due to the rise in temperature, the pressure inside the tube rises and exceeds a predetermined pressure. is defined as
Furthermore, when the temperature of the physiological saline rises, evaporation occurs, and along with this, the pressure inside the pipe increases as the volume increases, and the surface tension and frictional force around the generated steam rapidly decrease.
Therefore, by selecting the diameter of the small holes according to the wettability and viscosity of the liquid in the pipe, it is possible to discharge only the vapor generated in the liquid and separate the gas and liquid.

Using this principle, in a refrigerant circulation cooling system, a large amount of heat is absorbed by evaporating the liquid-phase refrigerant in the heat absorption part, and only the generated vapor is separated, and the liquid-phase refrigerant is circulated in this part. Cooling efficiency can be greatly improved by supplying it.
In a refrigerant circulation type cooling device typified by a heat pipe, it is preferable in terms of cooling efficiency that the refrigerant vaporized in the heat receiving portion is condensed in the cooling portion and then circulated to the heat receiving portion by gravity. is arranged above and the cooling unit is arranged below, the cooling efficiency will deteriorate.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the heat exchange efficiency of a refrigerant circulation type cooling device by smoothly transferring air bubbles remaining in an internal space around a heat source to a low-temperature part together with a refrigerant flow without requiring a special mechanism. In addition, even if the heat-receiving part and the cooling part are turned upside down, it is possible to circulate the coolant flow and prevent the deterioration of the cooling efficiency.

In order to achieve this object, the refrigerant circulation type cooling device according to the present invention comprises: a sealed space in which a refrigerant is enclosed; and an opening communicating between the heat receiving space and the cooling space. By selecting the diameter or width of the opening and the width and length of the heat receiving space, the amount of heat from the heat source The steam generated in the refrigerant in the heat receiving space is circulated through the opening to the cooling space, and the refrigerant condensed in the cooling space is circulated to the heat receiving space and constantly circulated and supplied to the opening.

According to the present invention, the vapor in the refrigerant generated in the heat receiving space by the amount of heat from the heat source can be ejected from the small hole with a selected diameter into the cooling space, and the refrigerant condensed in the cooling space can be pressure-fed to the heat receiving space. Therefore, the liquid-phase refrigerant is always circulated and supplied to the small holes, improving the heat exchange efficiency, and the refrigerant flow can be circulated even if the heat-receiving part and the cooling part are turned upside down.

FIG. 1 shows the overall structure of an embodiment according to the invention. FIG. 2 is a diagram showing a case where the embodiment based on the present invention is used upside down. FIG. 3 is a diagram showing a modification in which a heat receiving space is formed by partition walls. FIG. 4 is a diagram showing a case where the modified example of FIG. 3 is used upside down. FIG. 5 is a diagram showing an example in which the sealed space has an eight-shaped cross section. FIG. 6 is a diagram showing a case where the modified example of FIG. 5 is used upside down. FIG. 7 is a diagram showing an example in which the sealed space has a T-shaped cross section. FIG. 8 is a diagram showing a case where the modified example of FIG. 7 is used upside down. FIG. 9 is a diagram showing an example in which the condensed coolant is stored at the bottom by the partition wall inside the sealed space and circulated through the fine tubes.

This embodiment, as shown in FIG. 1, is applied to a top heat type cooling device in which a heat source to be cooled is brought into contact with the upper surface and cooling is performed on the lower surface.
Two pipes 1a and 1b arranged on the left and right sides in the vertical direction and horizontal pipes 1c and 1d connected to the upper and lower ends of the pipes are airtightly joined to each other so as to form a shape along the sides of the rectangle. form a closed space. This forms one unit of the cooling element in this embodiment, and in the figure, the heat source 2 to be cooled is on the upper surface of the tube 1a on the left in the vertical direction, and the upper surface of the tube 1c on the upper side in the horizontal direction is heat transferable. close to. In this embodiment, the upper portion of the vertically left tube 1a is the heat receiving space, and the portion of the horizontal tube 1c and the vertically right tube 1b that is in heat transferable contact with the low temperature region 3 is the cooling space. Configure.

The upper end of the vertically left tube 1a and the left end of the horizontally upper tube 1c, and the upper end of the vertically right tube 1b and the right end of the horizontally upper tube 1c are provided with a small hole 4 and a small hole as openings, respectively. 5 are in communication. In addition, a check valve 6 is provided in the pipe 1d on the lower side in the horizontal direction to release the pressure to the left side only when the pressure on the right side in the figure rises.

When the heat source 2 is at room temperature and the cooling device is not in operation, the refrigerant (water in this embodiment) is filled in the vertically left tube 1a, the horizontally lower tube 1d, and the vertically right tube 1b, and the surface tension As a result, the vertically left pipe 1a, which has a smaller inner diameter (hereinafter referred to as “pipe diameter”), is filled with refrigerant almost to the upper end and is higher than the water level of the vertically right pipe 1b, which has a larger pipe diameter. In this embodiment, the upper portion of the horizontal upper pipe 1c and the upper portion of the vertical right pipe 1b are in a vacuum state before operation of the cooling device.
At this time, the rising height h of the liquid level is given by the following equation.
h=2T·cos θ/ρgr
where T is the surface tension, θ is the contact angle, ρ is the refrigerant density, g is the gravitational acceleration, and r is the pipe diameter.
The diameter of the pipe 1a on the left side in the vertical direction and the pipe diameter of the pipe 1b on the right side in the vertical direction are in the range of 10 μm to 100 mm. The pipe diameters of the horizontally upper pipe 1c and the horizontally lower pipe 1d can be arbitrarily selected so as to satisfy the difference.

In this state, when the temperature of the heat source 2 rises and the cooling device is operated, the refrigerant temperature rises sharply at the upper surface of the vertically left pipe 1a in contact with the heat source 2, and the refrigerant evaporates and absorbs a large amount of heat. do. Along with this, bumping occurs, and the internal pressure around the small hole 4 rises intermittently in the left tube 1a in the vertical direction. Thus, in this embodiment, the space above the pipe 1a on the left side in the vertical direction constitutes the heat receiving space.
As the internal pressure rises sharply, the refrigerant tries to move to the 1d side through the narrow tube 1a or to the space 1c side through the small hole 4 . In the present invention, most of the refrigerant passes through the small holes 4 by adjusting the inner diameter, length, friction between the refrigerant and the inner surface of the tube, surface tension, inertial force of the refrigerant, etc. The diameter of the small hole 4 and the like are set so that the water is ejected into the tube 1c on the upper side in the horizontal direction.

ただし、ｆは管摩擦係数、Ｌは配管長さ(m)、Ｄは管径(m)、Ｖは管内流速(m/s)、ρは 流体の密度(kg/m³)である。
管内径0.1mm、長さ20mmの細管にあけられた小孔４の直径を0.02mm、管厚さ0.05mmとし、流体密度、管摩擦係数、管内流速を一定と仮定すると、細管内面と冷媒の摩擦による圧力損失は、小孔の内面と冷媒の摩擦による圧力損失の80倍となる。つまり、小孔４周辺の圧力上昇は主に小孔４を介して解放されようとする。
さらに流体が水で密度可変とすると、管径の小さい管１ａ内のほとんどが水で満たされている状態で、密度比が約1700分の1の蒸気が小孔４の周辺に発生すると、両者の圧力損失の差の飛躍的な拡大に伴い、発生した蒸気は、垂直方向左側の管１ａ内に滞留することなく小孔４から排出されることになる。 Here, when the volume of the refrigerant expands as the refrigerant evaporates due to the heating of the heat source, the pressure loss due to friction against the expansion inside the narrow tubes and inside the small holes is as follows from the Darcy-Weisbach formula:

where f is the pipe friction coefficient, L is the pipe length (m), D is the pipe diameter (m), V is the pipe flow velocity (m/s), and ρ is the fluid density (kg/m ³ ).
Assuming that the diameter of the small hole 4 drilled in a tube with an inner diameter of 0.1 mm and a length of 20 mm is 0.02 mm and the tube thickness is 0.05 mm, and that the fluid density, tube friction coefficient, and flow velocity inside the tube are constant, the flow rate between the inner surface of the tube and the refrigerant is The pressure loss due to friction is 80 times the pressure loss due to friction between the inner surface of the small holes and the refrigerant. In other words, the pressure increase around the small hole 4 tries to be released mainly through the small hole 4 .
Furthermore, if the fluid is water and the density is variable, when most of the inside of the pipe 1a with a small pipe diameter is filled with water, and steam with a density ratio of about 1/1700 is generated around the small hole 4, both With the dramatic increase in the pressure loss difference between the two, the generated steam is discharged from the small hole 4 without remaining in the pipe 1a on the left side in the vertical direction.

Refrigerant vapor ejected from the small hole 4 fills the horizontally upper tube 1c, which was in a vacuum state, with vapor pressure of the refrigerant, and then passes through the small hole 5 and enters the vertically right tube 1b. Since the horizontally upper pipe 1c and the vertically right pipe 1b are in contact with the low-temperature region 3 so as to allow heat transfer, the refrigerant vapor flows toward the connection portion with the horizontally lower pipe 1d. It descends while gradually condensing in region 3. In this embodiment, a portion of the horizontally upper tube 1c and the inner space of the vertically right tube 1b, which are in contact with the low temperature region 3, form a cooling space.
In the horizontal lower pipe 1d, as the refrigerant vapor enters the vertical right pipe 1b, the internal pressure rises, and the condensed refrigerant flows through the check valve 6 into the vertical left pipe 1b. is discharged to the connecting portion side, and flows back into the pipe 1a on the left side in the vertical direction again.

The diameter of the small holes 4 varies depending on the physical properties of the refrigerant (viscosity, surface tension, etc.) and the application and specifications of the cooling device, but is selected in the range of 1-1000 μm, and is drilled by ultra-precision processing developed by the inventors. By performing processing, it is possible to realize the above-described effects. In the embodiment, the small holes 4 are provided in two stages, upper and lower, in order to efficiently diffuse heat by steam, but the number and arrangement of the small holes 4 can be selected arbitrarily. Further, a spiral opening may be formed in the upper surface of the narrow tube 1a, and the refrigerant vapor may be ejected from this opening into the horizontally upper tube 1c. Even if the opening is made longer, if the width of the opening satisfies the above conditions, the refrigerant vapor can be selectively discharged. Since the opening width/surface area can be increased compared to the small holes, the discharge efficiency of the refrigerant vapor can be improved in some cases.
In addition, the small hole 5 in the pipe 1b on the right side in the vertical direction has the effect of promoting the circulation of the refrigerant, but it is not necessary to strictly set the pipe diameter. Alternatively, the horizontal upper pipe 1c and the vertical right pipe 1b may be directly connected.
In addition, in the interior of the pipe 1a on the left side in the vertical direction adjacent to the heat source 2, if the inertia of the refrigerant in the pipe and the fluid resistance with the inner wall of the pipe are so large that those of the small holes 4 can be ignored, the check valve 6 is not necessary. No need to set.

FIG. 2 shows a case in which the cooling device is turned upside down, the heat source 2 to be cooled is brought into contact with the bottom surface, and the cooling device is applied to a bottom heat type cooling device in which cooling is performed on the top surface.
In this case, the lower part of the tube 1a located on the right side in the vertical direction is the heat receiving space, and the low temperature area 3 A cooling space is formed by a portion that is in heat transferable contact with the .
In this state, when the temperature of the heat source 2 rises and the cooling device is operated, in the pipe 1a located on the left side in the vertical direction in contact with the heat source 2, bumping occurs as the refrigerant temperature rises rapidly at the bottom portion, and the vapor of the refrigerant occurs. As a result, the internal pressure around the small hole 4 rises intermittently.

With this rapid increase in internal pressure, most of the steam passes through the small holes 4 and is jetted out into the pipe 1c positioned horizontally below.
Refrigerant vapor ejected from the small hole 4 fills the pipe 1c located in the horizontal lower side, which was in a vacuum state, with the vapor pressure of the refrigerant, passes through the small hole 5, and enters the pipe 1b located on the left side in the vertical direction. Then, it rises toward the connecting portion with the pipe 1d located horizontally above. By strictly controlling the diameter of the small holes 5, it is possible to prevent the liquid refrigerant from entering from the opposite direction while realizing the movement of vapor from the pipe 1c to the pipe 1b.

When the pipe 1b located on the left side in the vertical direction and the pipe 1d located in the upper side in the horizontal direction are brought into heat transferable contact with the low temperature region 3, the refrigerant vapor is sequentially condensed and the pipes located in the lower side in the horizontal direction are condensed. Due to the increase in the pressure inside the pipe from 1c, it is discharged through the check valve 6 to the side of the connection with the pipe 1a located on the right side in the vertical direction, and again flows back to the pipe 1a on the right side in the vertical direction, repeating the above operation. become.
In addition, in the pipe 1a located on the right side in the vertical direction, if the water level of the refrigerant is always maintained higher than the upper opening (boundary with the pipe 1d) of the pipe 1a, which is the refrigerant supply port, the circulation of the refrigerant is prevented. can be realized.

In the above embodiment, one unit of the cooling element is formed by combining four pipes, but as shown in FIG. A first partition wall 7 partitions only the area in contact with the heat source 2 so as to be able to conduct heat, and defines a heat-receiving space. Another space in the sealed space that is in contact with the low-temperature region 3 in a heat transferable manner may be used as a cooling space, and the small holes 4 may be formed in the upper portion of the first partition wall 7 toward this cooling space.
As shown in FIG. 4, even when this modification is turned upside down, the refrigerant can be circulated on the same principle as in FIG.
In order to prevent the vapor bubbles discharged from the small holes 4 from moving to the outlet part along the narrow tubular section, a second section extending horizontally above the small holes 4 is shown in FIG. A wall 8 and a third partition wall 9 extending parallel to the axial direction of the capillary tube are provided near the outlet of the capillary tube. The minimum required is fine.

In the above embodiments, one unit of the cooling element has been described, but a plurality of units of the cooling element may be integrated.
In FIG. 5, the sealed space has an 8-shaped cross section, the central portion of the bottom surface is the contact portion with the heat source, and as shown in the partial enlarged view, small holes 4 each having a strictly adjusted diameter are formed around the portion. This is an example in which a bundle of thin tubes 10 provided at the bottom is provided. In this case, the bottom side of each thin tube 10 forms a heat receiving space, and the other part provided with the cooling fins 11 for exchanging heat with the low temperature region forms a cooling space.
With this configuration, the amount of refrigerant is adjusted so that the refrigerant always covers the outlet of the thin tube 10, which is the supply port of the refrigerant, even in the state of FIG. 5 or standing upright as in FIG. You can set it.
In this example, a partition wall 12 is provided to cover the bundle of thin tubes 10 in the vertical direction and prevent refrigerant vapor from adhering to the outlet of the thin tubes 10 .

Furthermore, as shown in FIG. 7, the sealed space has a T-shaped cross section, and around the heat source contact part on the upper surface, a bundle of small tubes 10) having a small hole at the bottom with a strictly adjusted diameter is provided, By providing the cooling fins 11 for exchanging heat with the low-temperature region on the other surface, it is possible to function as a cooling device even when inverted as shown in FIG. Also in this example, a partition wall 12 is provided at the outlet of the thin tube 10 to prevent refrigerant vapor from adhering.
In the case of FIG. 7, the liquid-phase refrigerant is supplied upward toward the heat source 2 due to the pressure rise of the refrigerant vapor ejected from the small holes of the narrow tube 10 and the surface tension in the narrow tube 10. .
Furthermore, by devising the shape of the partition wall 12, in the state of FIG. Refrigerant can be supplied to near the heat source at high speed by the supply of refrigerant and water pressure.
In addition, various modifications are possible, such as connecting the cooling elements radially according to the size of the heat source.

In addition, when the orientation of the cooling element is limited to some extent and the cooler is driven with a small amount of refrigerant, as shown in FIG. The refrigerant can be circulated by storing it in the thin tube 10 and returning it to the thin tube 10 .

As described above, according to the present invention, the vapor in the refrigerant generated in the heat receiving space by the amount of heat from the heat source can be ejected into the cooling space, and the refrigerant condensed in the cooling space can be pumped to the heat receiving space. In addition to improving the heat exchange efficiency, it is possible to circulate the refrigerant flow even if the heat receiving part and the cooling part are turned upside down. There is expected.

1a to 1d: pipe 2: heat source to be cooled 3: low temperature region 4, 5: small hole 6: check valve 7: first partition wall 8: second partition wall 9: third partition wall 10: narrow tube 11: cooling Fin 12: Partition

Claims (4)

Equipped with a heat receiving space adjacent to a heat source and a cooling space in contact with a low temperature region so as to be able to exchange heat, which are partitioned in a sealed space with a refrigerant enclosed therein,
The heat receiving space has a first tube, an end of the first tube receiving heat from the heat source,
the cooling space has a second tube, the first tube having a smaller diameter than the second tube;
The first pipe is filled with the liquid-phase refrigerant, and has an opening on the side surface of the end that communicates the heat-receiving space and the cooling space, and the liquid-phase refrigerant flows through the opening. The size of the opening is set so as not to leak into the cooling space,
When the heat-receiving space receives heat from the heat source, the liquid-phase refrigerant vaporizes at the end of the first pipe to generate steam, which is then released from the opening provided on the side surface of the end. A refrigerant circulation type cooling device in which steam is jetted into the cooling space. 2. The refrigerant circulation type cooling device according to claim 1, wherein said sealed space has a cylindrical interior, and said first pipe defining said interior in a tubular shape is arranged. Having a plurality of the first tubes,
The end of each of the plurality of first tubes receives heat from the heat source, and the plurality of first tubes are arranged parallel to each other,
2. The refrigerant circulation type cooling device according to claim 1, wherein said plurality of first pipes are entirely filled with said liquid-phase refrigerant, including an end portion opposite to said end portion. 4. The refrigerant circulation type cooling device according to claim 3, further comprising a partition wall for preventing the vapor of said spouted refrigerant from reaching said other ends of said plurality of first pipes.

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