CN116518760A - A Split Channel Type Flat Loop Heat Pipe - Google Patents

Abstract

The invention provides a split channel type flat plate loop heat pipe, which includes an evaporator, a steam pipeline, a condenser and a liquid pipeline connected in sequence, and the evaporator includes an upper cover plate, a lower base body, and an upper cover plate and a lower base body. The upper cover plate includes a liquid inlet and a steam outlet, the intermediate body includes a compensation chamber and a steam chamber, the compensation chamber communicates with the liquid inlet, the steam chamber communicates with the steam outlet, and a capillary wick is set in the evaporator, and the capillary wick includes a high The heat conduction capillary core and the low heat conduction capillary core, the high heat conduction capillary core is arranged on the lower substrate, and is thermally connected with the heat source, and the low heat conduction capillary core is arranged on the upper part of the high heat conduction capillary core, and communicated with the steam chamber. The evaporator designed in the present invention can form multiple vapor-liquid interfaces at the capillary core with high thermal conductivity, which greatly increases the liquid suction capacity of the capillary core, and is beneficial to improving the heat transfer characteristics of the loop heat pipe.

Description

A Split Channel Type Flat Loop Heat Pipe

technical field

The invention relates to the field of heat exchange, in particular to a split channel type flat plate loop heat pipe.

Background technique

Heat pipe technology uses the heat transfer theory and the rapid heat transfer properties of phase change media to quickly transfer the heat from the heating source to the outside of the heat source through the heat pipe, and its thermal conductivity exceeds any known metal. Therefore, since the heat pipe technology came out, it has become a research hotspot of many scholars at home and abroad in recent decades.

The loop heat pipe is an extension of the traditional heat pipe technology and is a highly efficient two-phase heat transfer device. The evaporator and the condenser are connected into a loop through the steam pipeline and the liquid pipeline, and only the capillary force provided by the capillary core is used to drive the circulation of the working fluid in the tube, without additional energy consumption, and the phase change of the working fluid is used to transfer heat. The structural characteristics of the loop heat pipe are: the separation of the steam pipeline and the liquid pipeline, and the integration of the evaporator and the compensator. Because of the compact structure, the gas-liquid carrying resistance is small, the startup is fast and flexible, it has good heat transfer capacity, and is easy to install. It is widely used in military industry, aerospace, electronic equipment and many other fields due to its characteristics of long-distance heat transmission.

The loop heat pipe is mainly composed of evaporator, capillary core, compensation cavity, steam pipeline, liquid pipeline and condenser. The working principle of the loop heat pipe is: the heat from the heat source is transferred to the working medium through the heat conduction of the evaporator, the liquid working medium absorbs heat, the temperature rises and undergoes a phase change, evaporates on the outer surface of the capillary core, and the generated steam flows out from the steam channel into the steam pipe , and then enter the condenser to condense into liquid, and the condensate enters the compensation chamber along the liquid pipeline to compensate the capillary wick under the push of the steam pressure, and this part of the reflux liquid is sucked into the capillary wick again through the capillary suction of the capillary wick to absorb heat and evaporate. So repeated to form a complete cycle process. The capillary wick is the core part of the evaporator and even the loop heat pipe, because the driving force of the entire loop is provided by the capillary force of the capillary wick, so the design of the capillary wick or the design of the evaporator determines the overall performance of the loop heat pipe.

Although the loop heat pipe has the above advantages, it is more suitable for application scenarios with limited internal space. However, the traditional loop heat pipe has the problem of heat leakage because the evaporator and the compensation chamber are located on the same substrate. Part of the heat is transferred to the compensation chamber along the axial direction, and the reflux liquid flowing through the compensation chamber absorbs this part of heat and evaporates. , causing the circulation process to be blocked, the operation to be unstable, and even the heat pipe to fail.

In addition, the vapor-liquid interface formed in the capillary core of the traditional flat-plate loop heat pipe is limited, which limits the suction performance of the capillary core and greatly reduces the heat dissipation performance of the loop heat pipe; at the same time, the area of the condensate return channel of the traditional loop heat pipe is limited, This also reduces the heat transfer performance of the loop heat pipe.

Contents of the invention

In view of the above problems, the present invention provides a design of a split-channel flat plate loop heat pipe, which can not only effectively prevent the large heat leakage of the evaporator and the compensation chamber, but also avoid the interruption of circulation and the failure of the heat pipe due to heat entering the compensation chamber. Moreover, it increases the vapor-liquid interface inside the capillary core, strengthens the suction effect of the capillary core on the liquid, increases the effective condensation return area, and improves the overall heat dissipation capacity and heat transfer performance of the loop heat pipe.

In order to achieve the above object, the technical scheme of the present invention is as follows:

A split channel type flat plate loop heat pipe, including an evaporator, a steam pipeline, a condenser and a liquid pipeline connected in sequence, the evaporator includes an upper cover, a lower base, and an upper cover and a lower base between the upper cover and the lower base. The intermediate body, the upper cover plate includes a liquid inlet and a steam outlet, the intermediate body includes a compensation chamber and a steam chamber, the compensation chamber communicates with the liquid inlet, the steam chamber communicates with the steam outlet, and a capillary wick is arranged in the evaporator, The capillary core includes a high thermal conductivity capillary core and a low thermal conductivity capillary core. The high thermal conductivity capillary core is arranged on the lower substrate and is thermally connected to the heat source. The low thermal conductivity capillary core is arranged on the upper part of the high thermal conductivity capillary core and communicated with the steam chamber.

In an improvement, at least a part of the low thermal conductivity capillary core is arranged at the lower part of the steam chamber.

In an improvement, the edge of the upper cover plate extends downward to the edge of the lower base body, for wrapping the intermediate body and the capillary core between the upper cover plate and the lower base body.

An improvement, the low thermal conductivity wick and the shell outside the liquid return channel are made of low thermal conductivity material.

A heat exchange method for a split-channel flat plate loop heat pipe as described above. The lower substrate is heated by the heating element, and the heat is transferred to the capillary core with high thermal conductivity through heat conduction. The working fluid in the loop heat pipe absorbs this part of the heat and undergoes a phase change. And generate steam, the steam enters the steam channel through the gap in the porous medium, then enters the steam chamber to collect, enters the steam pipeline through the steam outlet, and then enters the condenser to condense into a liquid working medium. This part of the reflux liquid is first sucked into the low thermal conductivity capillary core by the capillary force of the capillary core, and then sucked into the high thermal conductivity capillary core by the capillary force of the high thermal conductivity capillary core. Multiple vapor-liquid interfaces are formed.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention adopts a combination of high thermal conductivity capillary core and low thermal conductivity capillary core, wherein the high thermal conductivity capillary core such as foamed copper ensures that all or most of the heat from the heating element is transferred to the working medium. The upper part adopts a low thermal conductivity capillary core to prevent the condensed and returned liquid from being heated and evaporated, causing the return flow to be blocked.

(2) The thermal conductivity of the capillary core with high thermal conductivity and the capillary core with low thermal conductivity is very different, so that all or most of the heat from the heating element can be transferred to the working fluid. The upper part adopts a low thermal conductivity capillary core to prevent the condensed and returned liquid from being heated and evaporated, causing the return flow to be blocked.

(3) The present invention increases the liquid return channel, increases the effective condensation return area, and improves the overall heat dissipation capacity and heat transfer performance of the loop heat pipe.

(4) Two meniscus interfaces can be formed between each capillary core with low thermal conductivity and high thermal conductivity capillary core. This also increases the vapor-liquid interface compared with the traditional heat pipe, greatly increases the capillary force of the capillary core, strengthens the suction effect of the capillary core on the liquid, and improves the heat transfer performance.

(5) Based on this structure, it can effectively prevent the evaporator and the compensation cavity from having a large heat leakage problem due to the same substrate, and at the same time avoid the heat from entering the compensation cavity along the axial direction to cause the working fluid to evaporate, resulting in cycle interruption and heat pipe failure. issues such as failure.

Description of drawings

Fig. 1 is the overall system diagram of the loop heat pipe of the present invention.

Fig. 2 is a disassembled schematic diagram of the evaporator of the present invention.

Fig. 3 is a schematic perspective view of the evaporator intermediate of the present invention.

Fig. 4 is a top view of the intermediate body of the evaporator of the present invention.

Fig. 5 is a bottom view of the intermediate body of the evaporator of the present invention.

Fig. 6 is a schematic diagram of the operation of the evaporator of the present invention.

In the picture:

1. Evaporator, 2. Capillary, 3. Steam line, 4. Condenser, 5. Liquid line, 6. Compensation chamber, 7. Steam channel, 8. Steam chamber, 9. Steam outlet, 10. Liquid Inlet, 11. Liquid return channel, 12. Upper cover plate, 13. Lower substrate, 14. Intermediate body, 21. High thermal conductivity capillary core, 22. Low thermal conductivity capillary core.

Detailed ways

The specific embodiment of the present invention will be described in detail below in conjunction with the accompanying drawings.

In this article, if there is no special explanation, when it comes to formulas, "/" means division, and "×" and "*" mean multiplication.

As shown in Figure 1-6, a split-channel flat plate loop heat pipe includes an evaporator 1, a steam pipeline 3, a condenser 4 and a liquid pipeline 5 connected in sequence, and the fluid absorbs heat and evaporates in the evaporator 1 , and then enter the condenser 4 through the steam line 3 for exothermic condensation into liquid, and then the liquid enters the evaporator 1 through the liquid line 5, thus forming a cycle.

As shown in Figure 2, the evaporator 1 includes an upper cover plate 12, a lower base body 13 and an intermediate body 14 between the upper cover plate 12 and the lower base body 13, the upper cover plate 12 includes a liquid inlet 10 and a steam outlet 9, and the liquid inlet 10 and the steam outlet 9 are connected to the liquid pipeline 5 and the steam pipeline 3 respectively. The intermediate body 14 includes a compensation chamber 6 and a steam chamber 8, the compensation chamber 6 communicates with a liquid inlet 10 for introducing liquid into the compensation chamber. The steam chamber 8 communicates with the steam outlet 9 . The evaporator 1 is provided with a capillary core 2, the capillary core 2 includes a high thermal conductivity capillary core 21 and a low thermal conductivity capillary core 22, the high thermal conductivity capillary core 21 is arranged on the lower substrate 13, and is thermally connected with the heat source, and the low thermal conductivity capillary core 22 is arranged on the high thermal conductivity The upper part of the capillary core 21 communicates with the steam chamber 8 .

The invention adopts the combination of high thermal conductivity capillary core and low thermal conductivity capillary core, wherein the high thermal conductivity capillary core such as foamed copper ensures that all or most of the heat from the heating element is transferred to the working medium. The upper part adopts a low thermal conductivity capillary core to prevent the condensed and returned liquid from being heated and evaporated, causing the return flow to be blocked.

Preferably, the thermal conductivity of the high thermal conductivity wick is 130-800 times that of the low thermal conductivity wick. Preferably it is 200-500 times.

Preferably, the thermal conductivity of the high thermal conductivity capillary wick is generally between 80-400W/(m·K), which is higher than that of ordinary metals. The high thermal conductivity wick used is preferably porous copper metal foam; while the thermal conductivity of the low thermal conductivity wick is generally between 0.2-0.3 W/(m·K), preferably PTFE.

Only when the thermal conductivity of the capillary core with high thermal conductivity and the capillary core with low thermal conductivity is very large can the heat from the heating element be completely or mostly transferred to the working fluid. The upper part adopts a low thermal conductivity capillary core to prevent the condensed and returned liquid from being heated and evaporated, causing the return flow to be blocked. If the thermal conductivity of the high thermal conductivity wick is too low and the thermal conductivity of the low thermal conductivity wick is too high, and the multiple gap between the two is too small, the technical effect will become poor, and the heat exchange and energy absorption will be greatly reduced.

The thickness of the capillary core with two thermal conductivity can be designed according to the specific application situation. The capillary force of the capillary core depends on the mesh number, porosity and effective capillary radius. If the thickness of the capillary core is insufficient, it cannot provide sufficient capillary force; if the thickness of the capillary core If it is too large, the permeability will decrease. Finally, the working fluid will return to the capillary core with high thermal conductivity. Therefore, the capillary force of the capillary core with high thermal conductivity is stronger than that of the capillary core with low thermal conductivity.

The high thermal conductivity capillary core is arranged on the lower substrate and is thermally connected with the heat source, and the low thermal conductivity capillary core is arranged on the upper part of the high thermal conductivity capillary core and communicates with the liquid return channel. The reason why the shunt channel structure is introduced is that the vapor and liquid are separated without direct contact, and the vapor-liquid interface is increased, which greatly increases the capillary force of the capillary core, which is conducive to improving the heat transfer characteristics; the effective condensing return area is greatly increased, and the loop is improved. The overall heat dissipation capability of the heat pipe is conducive to improving the heat transfer performance of the loop heat pipe.

As shown in FIG. 3 , the present invention designs a plurality of liquid return channels 11 . The liquid return channel means that the working fluid enters the compensation chamber after condensation and then flows into the evaporator. Each liquid return channel is connected with the low thermal conductivity capillary core, and the low thermal conductivity capillary core is arranged on the upper part of the high thermal conductivity capillary core, and the liquid in the low thermal conductivity capillary core flows into the high thermal conductivity capillary core under the action of gravity and capillary force, each Two menisci can be formed between the capillary core with low thermal conductivity and the capillary core with high thermal conductivity. This also increases the vapor-liquid interface compared with traditional heat pipes, greatly increasing the capillary force of the capillary core.

In an improvement, at least a part of the low thermal conductivity capillary core is arranged at the lower part of the steam chamber. Evaporation efficiency can be further improved.

In an improvement, the edge of the upper cover plate extends downward to the edge of the lower base body, for wrapping the intermediate body and the capillary core between the upper cover plate and the lower base body. The above-mentioned design covers the intermediate body, so that the intermediate body can be better protected from damage.

An improvement, the low thermal conductivity wick and the shell outside the liquid return channel are made of low thermal conductivity material. In addition to the above-mentioned functions, the shell also prevents the liquid working medium flowing through the capillary core with low thermal conductivity from contacting with steam, preventing heat leakage, which may cause failure of the heat pipe or decrease in heat transfer performance of the heat pipe.

As shown in Figure 2, in the evaporator designed by the present application, each low thermal conductivity capillary wick 22 can form two meniscus interfaces at the high thermal conductivity capillary wick 21, while the traditional heat pipe only forms one vapor-liquid interface at the capillary wick. . The liquid suction capacity of the capillary is greatly increased, which is conducive to improving the heat transfer characteristics of the loop heat pipe; at the same time, this application also has an innovative design point. Based on this structure, the effective condensation return area of the loop heat pipe is greatly increased, improving the environmental performance. The overall heat dissipation capacity of the loop heat pipe is improved, and the working cycle is more stable, which is conducive to improving the heat transfer performance of the loop heat pipe.

The working process of the heat pipe of the present invention is as follows: the lower substrate 13 is heated by the heating element, and the heat is transferred to the high thermal conductivity capillary core 21 through heat conduction. The gap enters the steam channel 7, and then enters the steam chamber 8 to collect, enters the steam pipeline 3 through the steam outlet 9, and then enters the condenser 4 to condense into a liquid working medium. The condensate flows into the liquid pipeline 5 under the action of steam pressure. In the compensation chamber 6, the liquid returns through the liquid return channel 11. This part of the return liquid is first sucked into the low thermal conductivity capillary core 22 by the capillary force of the capillary core, and then sucked into the high thermal conductivity capillary core 21 by the capillary force of the high thermal conductivity capillary core. This forms multiple vapor-liquid interfaces, increases capillary suction and enhances heat transfer capabilities. The condensate absorbs heat and evaporates again, and so on, to complete the entire work process.

Although the present invention has been disclosed above with preferred embodiments, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Claims (8)

1. The utility model provides a dull and stereotyped loop heat pipe of reposition of redundant personnel passageway, includes evaporator, steam line, condenser and the liquid pipeline of circulating connection in proper order, its characterized in that, the evaporator includes upper cover plate, lower base member and is located the intermediate between upper cover plate and the lower base member, the upper cover plate includes liquid inlet and steam outlet, and the intermediate includes compensation chamber and steam chamber, compensation chamber and liquid inlet intercommunication, steam chamber and steam outlet intercommunication, set up the capillary core in the evaporator, the capillary core includes high heat conduction capillary core and low heat conduction capillary core, high heat conduction capillary core sets up on the lower base member, is connected with the heat source heat, and low heat conduction capillary core sets up in high heat conduction capillary core upper portion, communicates with the steam chamber, and wherein high heat conduction capillary core coefficient is 130-800 times of low heat conduction capillary core coefficient.

2. The split channel flat loop heat pipe of claim 1, wherein at least a portion of the low thermal conductivity wick is disposed in a lower portion of the vapor chamber.

3. The split channel flat loop heat pipe of claim 1, wherein the edge portion of the upper cover plate extends downwardly to the edge portion of the lower base body for wrapping the intermediate body and the wick between the upper cover plate and the lower base body.

4. The split channel flat loop heat pipe as claimed in claim 1 wherein the low thermal conductivity wick and the housing outside the liquid return channel are of a low thermal conductivity material.

5. The split-flow channel flat loop heat pipe as claimed in claim 1 wherein the high thermal conductivity wick has a thermal conductivity between 80 and 400W/(m-K); and the low heat conduction capillary core has a heat conduction coefficient of 0.2-0.3W/(m.K).

6. The split channel flat loop heat pipe of claim 1, wherein the high thermal conductivity wick thermal conductivity is 200-500 times the low thermal conductivity wick thermal conductivity.

7. The split channel flat loop heat pipe as claimed in claim 1, wherein the capillary force of the high thermal conductivity wick is stronger than the capillary force of the low thermal conductivity wick.

8. A method of heat exchange in a split-flow channel flat loop heat pipe as claimed in any one of claims 1 to 7 wherein the lower substrate is heated by a heating element, heat is transferred by conduction to a highly thermally conductive wick, the working medium in the loop heat pipe absorbs the heat to undergo a phase change and produce steam, the steam enters the steam channel through the internal space of the porous medium and then enters the steam cavity for collection, enters the steam pipeline through the steam outlet, then enters the condenser for condensation to form a liquid working medium, the condensate flows into the compensation cavity along the liquid pipeline under the action of the vapor pressure, and flows back through the liquid return channel, the part of the return liquid is sucked into the low thermally conductive wick by the capillary force of the wick, and then is sucked into the high thermally conductive wick by the capillary force of the high thermally conductive wick, and a plurality of vapor-liquid interfaces are formed therein.