CN111954445A

CN111954445A - Ribbed column type efficient phase change cooling device and cooling method thereof

Info

Publication number: CN111954445A
Application number: CN202010820603.1A
Authority: CN
Inventors: 潘振海; 闫哲
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Biguiqing Technology Co ltd
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2020-11-17
Anticipated expiration: 2040-08-14
Also published as: CN111954445B

Abstract

The invention discloses a ribbed column type efficient phase change cooling device and a cooling method thereof, wherein the cooling device comprises a box body consisting of a cooling bottom plate and a top cover, a horizontal heat insulation plate is arranged in the box body, a recovery cavity is arranged above the horizontal heat insulation plate, a phase change cavity is arranged below the horizontal heat insulation plate, and a gap is reserved between the edge of the horizontal heat insulation plate and the inner wall of the box body and is used as a recovery port; a working medium outlet and a working medium inlet are distributed on the top cover, the lower end of the working medium outlet is positioned in the recovery chamber, the lower end of the working medium inlet is positioned in the phase change chamber, the working medium inlet is surrounded by a vertical heat insulation plate, and the lower end of the vertical heat insulation plate is connected with a hole in the center of the horizontal heat insulation plate; and in the phase change chamber, the cooling bottom plate is provided with forked rib columns. The invention has the advantages of simple and clear design, stable flow, uniformity, high efficiency and energy conservation, and can effectively solve the cooling problem of a microelectronic system under the condition of high heat flux density.

Description

Ribbed column type efficient phase change cooling device and cooling method thereof

Technical Field

The invention relates to the field of microelectronic system heat dissipation, in particular to a ribbed column type efficient phase change cooling device and a cooling method thereof.

Background

As microelectronic system performance has improved, thermal power has also increased. The traditional single-phase flow heat dissipation device cannot meet the heat dissipation requirement of high heat flux density. Phase change heat dissipation technology can use huge latent heat of evaporation, and has better heat dissipation performance, so that the phase change heat dissipation technology is widely used in the field of microelectronic heat dissipation in recent years.

However, the currently common parallel microchannel phase change cooling device has the following problems: (1) the flow stability is poor, the mutual influence among different micro-channels is large, and large pressure fluctuation and backflow phenomena occur. (2) Local drying is easy to occur, and the uniformity of heat dissipation is relatively poor. (3) The flow resistance and the pressure difference between the inlet and the outlet are large, and large pumping work is required to be consumed. The heat dissipation problem restricts the further development of microelectronic systems, and therefore needs to be solved urgently.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a novel rib column type efficient phase change cooling device and a cooling method thereof.

The invention is realized by the following technical scheme:

a ribbed column type efficient phase change cooling device comprises a box body consisting of a cooling bottom plate and a top cover, wherein a horizontal heat insulation plate is arranged in the box body, a recovery cavity is arranged above the horizontal heat insulation plate, a phase change cavity is arranged below the horizontal heat insulation plate, a gap is reserved between the edge of the horizontal heat insulation plate and the inner wall of the box body and serves as a recovery port, and the recovery cavity is communicated with the phase change cavity;

a working medium outlet and a working medium inlet are distributed on the top cover, the lower end of the working medium outlet is positioned in the recovery chamber, the lower end of the working medium inlet is positioned in the phase change chamber, the working medium inlet is surrounded by a vertical heat insulation plate, and the lower end of a cylindrical vertical heat insulation plate is connected with a hole in the center of the horizontal heat insulation plate; the vertical heat insulation plate and the horizontal heat insulation plate are both made of materials with low heat conductivity;

in the phase change chamber, a cooling bottom plate is provided with bifurcate arrangement type rib columns;

the cooling bottom plate is made of high-thermal-conductivity material, and the bottom of the cooling bottom plate is connected with the cooled object.

The working medium inlet is positioned in the center of the top cover.

The recycling opening surrounds the periphery of the horizontal heat insulation plate.

And a gap is reserved between the top of the forked rib column and the lower surface of the horizontal heat insulation plate.

In the cooling method of the ribbed column type efficient phase change cooling device, the bottom of a cooling bottom plate is connected with an object to be cooled; liquid working medium enters the phase change chamber from the central position of the cooling bottom plate through the working medium inlet, then is diffused and flows through the surface of the branched arrangement type rib column, and a large amount of heat is absorbed by a vapor-liquid phase change process in the process; the vapor-liquid mixed working medium after phase change is collected into the recovery chamber through the recovery port and flows out of the phase change cooling device through the working medium outlet.

Wherein, the liquid working medium is environment-friendly refrigerant such as HFE-7100, FC-72 and the like, and can be selected according to the working conditions of the cooled equipment.

The beneficial effect of the invention is that,

compared with the prior art, the phase-change cooling device adopts the design mode of the cooling bottom plate with the branched distributed rib columns, the central inlet and the peripheral outlets, and is particularly suitable for heat dissipation of a microelectronic system under the condition of high heat flux density. After the invention is implemented, the invention has better flow stability, and can inhibit the phenomena of pressure fluctuation and backflow; the liquid is supplemented in time, and the heat dissipation efficiency and uniformity are higher; the flow resistance is small, and the pump work is obviously reduced. In addition, the invention has simple and clear structure and is easy to process and manufacture.

Drawings

FIG. 1 is a schematic external view of the present invention;

FIG. 2 is a front view of the present invention;

FIG. 3 is a central longitudinal sectional view (A-A) of the present invention;

FIG. 4 is a transverse cross-sectional view (B-B) of the present invention;

FIG. 5 is a transverse cross-sectional view (C-C) of the present invention;

fig. 6 shows rib post structures with different cross-sectional shapes.

Detailed Description

The specific technical scheme of the invention is explained by combining the attached drawings.

Fig. 1 is an appearance schematic diagram of a ribbed column type efficient phase change cooling device. The top cover 10 positioned on the upper part is tightly connected with the clamping groove 8 of the lower cooling bottom plate 7, so that the device is ensured to have good sealing performance. The working medium inlet 2 is positioned at the central position of the phase change cooling device, is surrounded by a vertical heat insulation plate 13, is tightly connected with a horizontal heat insulation plate 3 between a phase change chamber 6 and a recovery chamber 4 in the device into a whole, and is made of low-heat-conductivity materials. The working medium outlet 1 is positioned at the side of the working medium inlet 2, and the wall surface of the outlet and the top cover 10 are of an integrated structure. This figure also shows a central longitudinal section of the device, i.e. the position of fig. 3, through the central position of the working medium inlet 2 and the working medium outlet 1.

Fig. 2 is a front view of the ribbed-column efficient phase change cooling device showing two transverse cross-sectional views, the positions of fig. 4 and 5, wherein fig. 4 passes through the phase change chamber 6 and fig. 5 passes through the recovery chamber 4.

Fig. 3 is a central longitudinal sectional view (a-a) of the phase change cooling device, visually illustrating the specific layout of the cooling floor 7, the top cover 10 and the partitions. On the upper part of the cooling floor 7, bifurcate ribs 5 are provided, see fig. 5 in detail. The cooling bottom plate 7 is made of a material with high thermal conductivity, and can efficiently transfer heat and promote the uniformity of the temperature of the bottom plate.

A gap is arranged between the upper surface of the forked rib post 5 and the horizontal heat insulation plate 3, so that the contact area between the working medium and the surface of the cooling bottom plate 7 can be increased, and the heat exchange performance is effectively improved.

When the liquid working medium flows into the phase change chamber 6 below the horizontal heat insulation plate 3, the flowing direction of the liquid working medium can be divided into two parts: one part flows in the gaps of the bifurcate arrangement type rib columns 5; the other part flows in the gap between the bifurcate rib post 5 and the horizontal heat insulation plate 3.

Because the surface of the cooling bottom plate 7 has a certain superheat degree, the liquid working medium can be changed into a vapor-liquid mixed working medium by phase change when flowing through. The gas-liquid mixed working medium flows into the recovery chamber 4 through the recovery port 9 between the horizontal heat insulation plate 3 and the top cover 10, and the recovery ports 9 are arranged around the cooling device. The recovery chamber 4 is located between the partition board and the top cover 10, has larger thickness and volume, and can reduce the flow resistance of the vapor-liquid mixed working medium in the recovery chamber, thereby improving the flow uniformity in the phase change chamber 6. The vapor-liquid mixed working medium flowing into the recovery chamber 4 finally converges at the position of the working medium outlet 1, and flows out of the phase-change cooling device through the working medium outlet 1, and the specific flow condition inside the phase-change cooling device is shown in fig. 5.

Because the vapor-liquid mixed working medium has a certain superheat degree, the areas of the recovery chamber 4 adjacent to the inlet channel and the phase change chamber 6 are all provided with heat insulation partition plates, so that the heating of the vapor-liquid mixed working medium on the liquid working medium can be effectively reduced, more sensible heat/latent heat is utilized in the phase change chamber 6, and the heat exchange efficiency is guaranteed.

Fig. 4 is a transverse sectional view (B-B) of the phase change cooling device, in which the upper half shows the flow pattern evolution between the divergently arranged rib columns 5 and the lower half shows the flow direction of the working medium between the divergently arranged rib columns 5.

The bifurcate rib post 5 shown in the schematic diagram is an elliptical rib post, and the specific structure thereof can be selected according to the actual cooling requirement. The cross-sectional shape of the bifurcate rib column 5 can be triangle, trapezoid, rectangle, rhombus, rectangle-arc, rectangle-triangle, airfoil, bionic streamline, as shown in fig. 6, and these structures are all within the protection scope of the present invention. Furthermore, if a larger cooling area is required, the number of the bifurcating rib columns 5 can be increased accordingly.

The branched distributed rib columns 5 on the upper part of the cooling bottom plate 7 adopt a branched arrangement mode. When the liquid working medium enters from the center of the square cooling bottom plate 7, the liquid working medium is diverged to flow to the periphery, the resistance of the flow mode is smaller than that of the flow in the parallel micro-channel, the power consumption of the liquid feeding pump can be reduced, and the liquid feeding pump has the characteristic of energy conservation. The fluid all produces the branching flow at the front end of every rib post, and this design can eliminate the stagnant area that flows, ensures that branching arrangement formula rib post 5 side surface different positions have relatively higher working medium velocity of flow, promotes whole heat dissipation intensity.

When the phase change cooling device works, heat is transferred to the cooling bottom plate 7 from a cooled object, the surface of the branched distributed rib column 5 has a certain superheat degree, and small bubbles are formed at the vaporization core part of the surface of the branched distributed rib column. The generated small bubbles grow continuously, and the small bubbles start to separate from the surface of the bifurcate arrangement type rib column 5 after the volume reaches a certain degree. At this point, the flow pattern structure within the phase change chamber 6 has switched from single phase flow to bubble flow. The bubbles separated from the surface of the bifurcate arrangement type rib column 5 gradually flow outwards under the pushing of the liquid, and the volume of the bubbles is still continuously increased. Because the vapor-liquid phase change of the vapor bubbles in the forming and growing processes can absorb a large amount of heat, the heat exchange coefficient of the wall surface is far larger than that of single-phase flow.

As the vapor bubbles occupy most of the volume between the rib posts, the growth of the vapor bubbles begins to be limited by the wall surfaces. The main heat exchange mechanism between the vapor bubble and the heating wall surface is thin liquid film evaporation. The thickness of the liquid film during evaporation of the thin liquid film has great influence on the phase-change heat exchange strength. The bifurcate arrangement type rib column 5 provided by the invention can enable the flow in the phase change chamber 6 to be in a divergent state, and the flow velocity of the working medium correspondingly presents a change trend gradually reduced from the center to the periphery. Under the lower flow velocity, the thickness of the liquid film between the vapor bubble and the heating wall surface can be correspondingly thinned, and the thinner liquid film thickness can strengthen the phase change heat exchange, so that the better cooling effect is realized, and the parallel micro-channel phase change cooling structure has excellent characteristics which are not possessed by the parallel micro-channel phase change cooling structure. In addition, the structure has the characteristics of timely liquid supplementing and evaporation prevention under the phase change working condition, and effectively promotes the uniformity of the temperature of the bottom plate.

The phase change cooling device is designed to be in a layout of a central inlet and peripheral outlets, and compared with a parallel micro-channel layout of a one-side inlet and a one-side outlet type, the phase change cooling device is more stable in flow when phase change occurs, small in pressure fluctuation and capable of better inhibiting a backflow phenomenon.

Claims

1. A ribbed column type efficient phase change cooling device is characterized by comprising a box body consisting of a cooling bottom plate (7) and a top cover (10), wherein a horizontal heat insulation plate (3) is arranged in the box body, a recovery cavity (4) is arranged above the horizontal heat insulation plate (3), a phase change cavity (6) is arranged below the horizontal heat insulation plate, a gap is reserved between the edge of the horizontal heat insulation plate (3) and the inner wall of the box body to serve as a recovery port (9), and the recovery cavity (4) is communicated with the phase change cavity (6);

a working medium outlet (1) and a working medium inlet (2) are distributed on the top cover (10), the lower end of the working medium outlet (1) is positioned in the recovery chamber (4), the lower end of the working medium inlet (2) is positioned in the phase change chamber (6), the working medium inlet (2) is surrounded by a vertical heat insulation plate (13), and the lower end of the vertical heat insulation plate (13) is connected with a hole in the center of the horizontal heat insulation plate (3); the vertical heat insulation plate (13) and the horizontal heat insulation plate (3) are both made of materials with low heat conductivity;

in the phase change chamber (6), a cooling bottom plate (7) is provided with bifurcate arrangement type rib columns (5);

the cooling bottom plate (7) is made of high-thermal conductivity material, and the bottom part is connected with the cooled object.

2. The ribbed column type efficient phase change cooling device as claimed in claim 1, wherein the working medium inlet (2) is located at the center of the top cover (10).

3. The ribbed column type efficient phase change cooling device as claimed in claim 1, wherein the recycling port (9) is formed around the horizontal heat insulation plate (3).

4. A rib column type efficient phase change cooling device as claimed in claim 1, wherein a gap is left between the top of the branched distributed rib column (5) and the lower surface of the horizontal heat insulation plate (3).

5. The cooling method of the ribbed column type efficient phase change cooling device according to any one of claims 1 to 4, wherein the bottom of the cooling bottom plate (7) is connected with an object to be cooled; liquid working media enter the phase change chamber (6) from the central position of the cooling bottom plate (7) through the working media inlet (2), then are diffused and flow through the surface of the bifurcate arrangement type rib column (5), and a large amount of heat is absorbed by a vapor-liquid phase change process in the process; the vapor-liquid mixed working medium after phase change is collected into the recovery chamber (4) through the recovery port (9) and then flows out of the phase change cooling device through the working medium outlet (1).