CN112179190A - Ultrathin flat-plate loop heat pipe of coupling ejector - Google Patents

Ultrathin flat-plate loop heat pipe of coupling ejector Download PDF

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Publication number
CN112179190A
CN112179190A CN202011053110.6A CN202011053110A CN112179190A CN 112179190 A CN112179190 A CN 112179190A CN 202011053110 A CN202011053110 A CN 202011053110A CN 112179190 A CN112179190 A CN 112179190A
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China
Prior art keywords
evaporator
ejector
liquid
heat pipe
loop heat
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Pending
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CN202011053110.6A
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Chinese (zh)
Inventor
魏进家
刘蕾
杨小平
张永海
袁博
崔晨乙
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Xian Jiaotong University
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Xian Jiaotong University
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Priority to CN202011053110.6A priority Critical patent/CN112179190A/en
Publication of CN112179190A publication Critical patent/CN112179190A/en
Pending legal-status Critical Current

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/0266Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with separate evaporating and condensing chambers connected by at least one conduit; Loop-type heat pipes; with multiple or common evaporating or condensing chambers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/0275Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/04Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
    • F28D15/046Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure characterised by the material or the construction of the capillary structure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D2015/0291Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes comprising internal rotor means, e.g. turbine driven by the working fluid

Abstract

An ultrathin flat plate type loop heat pipe coupled with an ejector comprises an evaporator, the ejector and a cooler; the evaporator is connected with the ejector, and the ejector is connected with the evaporator through the cooler; the evaporator comprises an evaporator bottom plate, a capillary core and an evaporator cover plate, and a cavity formed by sealing the evaporator bottom plate and the evaporator cover plate is a compensation cavity. Liquid absorption frames are arranged on three side edges of the capillary core, the bottom of each liquid absorption frame is immersed in liquid in the compensation cavity, and the compensation cavity is connected with the ejector through a liquid pipeline. According to the invention, the ejector is added, so that the adverse effect of the lateral heat conduction of the bottom plate of the evaporator is weakened, and the drying of the capillary core is delayed. The modified flexible stainless steel sintered felt has good impact resistance while reducing the thickness of the capillary core, reduces the contact thermal resistance, increases the liquid absorption area and improves the upper limit of the power of the ultrathin flat plate type loop heat pipe.

Description

Ultrathin flat-plate loop heat pipe of coupling ejector
Technical Field
The invention belongs to the field of cooling and heat dissipation of electronic components, relates to a heat pipe heat dissipation device, and particularly relates to an ultrathin flat plate type loop heat pipe of a coupling ejector.
Background
With the development of processing technology, electronic products are being integrated and miniaturized, and the heat generation amount is increased and the heat dissipation space is reduced. How to take away a large amount of heat in limited heat dissipation space, and then guarantee that electronic product is stable, reliable operation is the problem that awaits a urgent need to be solved.
The loop heat pipe is used as a high-efficiency heat transfer device for realizing heat transfer by utilizing working medium phase change, and has the advantages of no need of consuming external energy, no moving parts and the like. The flat-plate loop heat pipe has a compact structure, is convenient to be attached to a heat dissipation object, and has great application potential. The development trend of miniaturization of electronic products puts a strict requirement on the thickness of an evaporator, which is a heat absorbing part of the flat-plate loop heat pipe, and the demand of ultrathin flat-plate loop heat pipes is increasing continuously.
The existing ultrathin flat-plate loop heat pipe has the problems of insufficient capillary core liquid supply and low heat dissipation capacity. The evaporator of the flat-plate loop heat pipe can be divided into a reverse liquid supply type and a longitudinal liquid supply type according to the relationship between the liquid flowing direction and the heat flow direction in the capillary core. The reverse liquid supply type evaporator is characterized in that the liquid flowing direction in the capillary core is parallel and opposite to the heat flow direction, and the evaporator cover plate, the compensation cavity, the capillary core and the evaporator bottom plate are sequentially arranged along the thickness direction. The evaporator with the structure has short liquid supply distance to the capillary core and uniform liquid supply, but the minimum thickness of the evaporator is limited by the size of the compensation cavity, and the thickness is usually more than 10 mm. The liquid flow direction in the capillary core of the longitudinal liquid supply type evaporator is vertical to the heat flow direction, and the thickness of the evaporator with the structure can be thinner due to the horizontal arrangement of the compensation cavity and the capillary core, so that the evaporator is particularly suitable for heat dissipation in narrow space and is a preferred structure of an ultrathin flat plate type loop heat pipe. However, the liquid supply distance of the capillary core under the structure is long, so that the capillary core far away from the compensation cavity under high power is locally dried. In addition, the evaporator and the compensation cavity share the same bottom plate under the structure, and the lateral heat conduction of the bottom plate leads the compensation cavity side close to the evaporator to easily generate vapor bubbles, so that liquid in the compensation cavity is prevented from entering the capillary core, and the drying of the capillary core is accelerated. The problem of drying up of the capillary core limits the upper power limit of the ultrathin flat-plate loop heat pipe.
Meanwhile, the flat-plate loop heat pipe needs to thin the capillary wick to further reduce the thickness of the evaporator. At present, most of capillary cores are formed by sintering metal powder, the defects of strong brittleness, poor impact resistance and the like are exposed along with the reduction of the thickness, and the capillary cores are easy to break or fracture in the assembling and using processes.
Disclosure of Invention
The invention aims to solve the problem that a capillary core of the existing ultrathin flat-plate loop heat pipe is dried up under high power, and simultaneously solves the problems of strong brittleness, poor impact resistance and poor liquid absorption capability of the capillary core after the thickness is reduced, and provides the ultrathin flat-plate loop heat pipe of the coupling ejector.
In order to achieve the purpose, the invention adopts the technical scheme that:
an ultrathin flat plate type loop heat pipe coupled with an ejector comprises an evaporator, the ejector and a cooler; the evaporator is connected with the ejector, and the ejector is connected with the evaporator through the cooler;
the evaporator comprises an evaporator bottom plate, a capillary core and an evaporator cover plate, wherein a cavity formed by sealing the evaporator bottom plate and the evaporator cover plate is a compensation cavity, a plurality of steam channels are arranged on the evaporator bottom plate, and the capillary core is arranged on the steam channels; liquid absorption frames are arranged on three side edges of the capillary core, the bottom of each liquid absorption frame is immersed in liquid in the compensation cavity, and the compensation cavity is connected with the ejector through a liquid pipeline.
The invention is further improved in that the ejector comprises three layers of stainless steel plates which are attached together, the middle layer of stainless steel plate is a flow channel plate, a flow channel is processed on the flow channel plate, one end of the flow channel is communicated with the evaporator, and the other end of the flow channel is communicated with the cooler.
The invention has the further improvement that the three layers of stainless steel plates are jointed by adopting a solid diffusion welding or instantaneous liquid phase diffusion welding method;
the runner includes liquid nozzle, steam nozzle and hybrid chamber, and the steam nozzle both sides all are provided with liquid nozzle, and liquid nozzle, steam nozzle's one end and evaporimeter are linked together, and the other end is linked together with the hybrid chamber.
The invention has the further improvement that the steam nozzle is a flow channel with a reducing or reducing-gradually expanding structure, and the cavity of the mixing cavity is of a reducing-gradually expanding structure; the thickness of the flow channel plate is 1-1.5mm, and the flow channel is processed by a laser cutting method.
The invention has the further improvement that the steam channel is connected with the ejector; the liquid pipeline is a square pipe, and the steam pipeline is a square pipe or a flat pipe; the flow area of the vapor line is greater than the flow area of the liquid line.
The further improvement of the invention is that the capillary wick is prepared by the following process: uniformly paving stainless steel fibers in a nickel-based alloy die, applying pressure of 1-2MPa to the stainless steel fibers through the nickel-based alloy die, preserving heat at the temperature of 700-900 ℃ for 40-60min, and cooling to room temperature to obtain a flexible porous stainless steel sintered felt; then soaking the stainless steel sintered felt in acidic CuCl2And (4) obtaining a capillary core in the solution.
A further improvement of the invention is that the stainless steel fibers have a filament diameter of 10-60 μm.
The invention is further improved in that the thickness of the flexible porous stainless steel sintered felt is 0.6-1 mm.
A further development of the invention is that the acidic CuCl2The solution is prepared by mixing 1mol/L hydrochloric acid and 1mol/L CuCl2The solution is prepared according to the molar ratio of 1:1, and the soaking time is 60-90 s.
The invention has the further improvement that the cooler is a finned tube type air cooling or sleeve type water cooling cooler; the liquid suction frame and the capillary core are of an integral structure and are made of the same material.
Compared with the prior art, the invention has the following beneficial effects: the compensation cavity is connected with the liquid nozzle of the ejector, the ejector is used for removing a hot liquid/vapor-liquid mixture in the compensation cavity, and the low-temperature liquid at the outlet of the cooler is sucked into the compensation cavity, so that the temperature of the compensation cavity is effectively reduced, the adverse effect of the lateral heat conduction of the bottom plate of the evaporator on the liquid supplement of the capillary core is weakened, and the drying of the capillary core is delayed. Because the ejector weakens the adverse effect of the lateral heat conduction of the bottom plate of the evaporator, a heat insulation groove or a heat insulation insertion strip does not need to be processed between the compensation cavity and the steam channel, the compensation cavity is close to the steam channel to shorten the liquid supply distance of the capillary core, the drying of the capillary core is further delayed, and the power upper limit of the ultrathin flat plate type loop heat pipe is favorably improved.
Furthermore, the capillary core is a modified stainless steel sintered felt, so that the thickness of the capillary core is reduced, the impact resistance is good, and the thermal contact resistance is reduced. The surface modification is carried out on the soft stainless steel sintered felt with weak hydrophilicity, so that the soft stainless steel sintered felt has super-hydrophilic property, the suction characteristic of the internal porous structure of the soft stainless steel sintered felt is exerted, and the liquid absorption capacity of the capillary wick is improved. Meanwhile, a layer of copper covers the surface of the stainless steel fiber of the sintered felt after surface modification, so that the part of the sintered felt, which is in contact with the top of the steam channel, is copper, and the excellent heat conduction performance of the copper is favorable for conducting heat from the bottom plate of the evaporator to the lower surface of the capillary core for evaporation heat exchange, thereby reducing the contact thermal resistance. And the heat conductivity of stainless steel which is the main component of the capillary core is poor, so that the phenomenon that the liquid supply channel is blocked due to bubbles generated by overhigh temperature in the capillary core can be avoided.
Furthermore, the characteristics that the sintered felt can be cut and bent are fully utilized to process the liquid absorbing frame, the bottom of the liquid absorbing frame is immersed into the liquid in the compensation cavity, the liquid absorbing area of the capillary wick is greatly increased, and the liquid supply of the capillary wick can be still ensured even at low liquid filling rate.
Furthermore, three layers of stainless steel plates of the ejector are tightly attached through solid-state diffusion welding or instantaneous liquid-phase diffusion welding, so that the problems that a brazing welding rod is difficult to extend into a flow passage and welding slag is difficult to remove and block the flow passage in a conventional welding method are solved. Compared with the traditional cylindrical ejector, the ejector provided by the invention has the advantage that the thickness of the ejector is effectively reduced.
Drawings
FIG. 1 is a schematic diagram of an internal structure of an ultrathin flat loop heat pipe of a coupling ejector according to the present invention.
FIG. 2 is a perspective view of an ultra-thin flat loop heat pipe according to the present invention.
Fig. 3 is an exploded view of the evaporator of the present invention.
FIG. 4 is a sectional view of the evaporator of the present invention, wherein (a) is a sectional view taken perpendicularly to the direction of movement of the liquid in the compensation chamber, and (b) is a sectional view taken parallel to the direction of movement of the liquid in the compensation chamber.
FIG. 5 is a schematic view of a laser cut ejector flow plate of the present invention.
Wherein: 1 is an evaporator; 1-1 is an evaporator bottom plate; 1-2 is a capillary core; 1-3 is an evaporator cover plate; 1-4 are steam channels; 1-5 are compensation cavities; 1-6 is a liquid absorption frame; 1-7 is a positioning frame; 2 is a liquid pipeline; 3 is a steam pipeline; 4 is an ejector; 4-1 is a liquid nozzle; 4-2 is a steam nozzle; 4-3 is a mixing cavity; 5 is a first connecting pipeline; 6 is a cooler; and 7 is a second connecting pipeline.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
The ultra-thin of the ultra-thin flat-plate loop heat pipe in the invention means that the thickness of an evaporator is below 2 mm.
Referring to fig. 1 and 2, the ultrathin flat-plate loop heat pipe of the coupling ejector of the invention comprises an evaporator 1, an ejector 4 and a cooler 6. The evaporator 1 is connected with the ejector 4, and the ejector 4 is connected with the evaporator 1 through a first connecting pipeline 5, a cooler 6 and a second connecting pipeline 7.
The evaporator 1 comprises an evaporator bottom plate 1-1, a capillary core 1-2 and an evaporator cover plate 1-3, a cavity formed by sealing the evaporator bottom plate 1-1 and the evaporator cover plate 1-3 is a compensation cavity 1-5, a plurality of steam channels 1-4 are arranged on the evaporator bottom plate 1-1, and the capillary core 1-2 is arranged on the steam channels 1-4; liquid absorption frames 1-6 are arranged on three side edges of the capillary core 1-2, the bottoms of the liquid absorption frames 1-6 are immersed in liquid in the compensation cavities 1-5, and the compensation cavities 1-5 are connected with the ejector 4 through liquid pipelines 2.
Referring to fig. 3 and fig. 4 (a) and (b), the evaporator base plate 1-1 is milled from a copper plate. One side of the evaporator bottom plate 1-1 is attached to a heat dissipation object, a plurality of steam channels 1-4 are milled in the area of the other side corresponding to the heat dissipation object, and the area covered by the steam channels 1-4 is not smaller than the heat exchange surface of the heat dissipation object. The covered area of the steam channel 1-4 is connected on one side to the steam outlet of the evaporator 1 and on the other three sides to the compensation chamber 1-5. And milling a groove with the same depth as the steam channel at the position of the evaporator bottom plate 1-1 corresponding to the compensation cavity 1-5. A cuboid capillary core 1-2 is arranged above the steam channel 1-4, and liquid absorption frames 1-6 are arranged on three side edges of the capillary core 1-2; the bottom of the liquid absorbing frame 1-6 is immersed into the liquid in the compensation chamber 1-5, but is not in contact with the evaporator bottom plate 1-1. The evaporator 1 is provided with a vapor outlet, two liquid outlets and a liquid inlet on the side wall. The steam outlet connects the steam channels 1-4 with the steam pipeline 3, the two liquid outlets are positioned at the two sides of the steam outlet and connect the compensation cavities 1-5 with the liquid pipeline 2, and the liquid inlet is positioned on the side wall opposite to the steam outlet and connects the compensation cavities 1-5 with the second connecting pipeline 7. The end of the liquid line 2 extends into the liquid in the compensation chamber 1-5.
And a positioning frame 1-7 is arranged on the evaporator cover plate 1-3 to fix the capillary core 1-2. The compensation cavities 1-5 are connected with a cooler 6 through a second connecting pipeline 7; one end of the liquid pipeline 2 extends into the liquid in the compensation cavity 1-5, and the other end is connected with a liquid nozzle 4-1 of the ejector; the liquid pipeline 2 is a square pipe and is attached to the shell of the electronic product through a heat conducting material, and the heat of the hot liquid/vapor-liquid mixture in the pipeline is transferred to the atmosphere through the shell; the steam channel 1-4 is connected with the ejector steam nozzle 4-2 through a steam pipeline 3; the steam pipeline 3 is a square pipe or a flat pipe, the thickness of the pipeline is not increased while the flow area is increased, and the outer wall of the pipe is coated with a heat-insulating material; the flow area of the steam pipeline 3 is far larger than that of the liquid pipeline 2; the compensation cavity 1-5 is close to the steam channel 1-4 to shorten the liquid supply distance of the capillary core 1-2.
The ejector 4 is driven by steam generated by the evaporator 1 to pump hot liquid/steam-liquid mixture in the compensation cavities 1-5; the working medium at the outlet of the ejector 4 is cooled by the cooler 6 and then enters the compensation cavities 1-5.
The ejector 4 is tightly attached by three layers of stainless steel plates by adopting a solid-state diffusion welding or instantaneous liquid-phase diffusion welding method, the middle layer of stainless steel plate is a flow channel plate, and a flow channel is processed on the flow channel plate; the cooler 6 is a finned tube type air cooling or telescopic tube type water cooling cooler.
Referring to fig. 5, the thickness of the flow channel plate of the ejector 4 is 1-1.5mm, and the flow channel is processed by a laser cutting method and comprises two liquid nozzles 4-1, a steam nozzle 4-2 and a mixing cavity 4-3. The steam nozzle 4-2 is a flow channel with a tapered or tapered-tapered structure, the liquid nozzle 4-1 is arranged at two sides of the steam nozzle 4-2, one end of the liquid nozzle 4-1 and one end of the steam nozzle 4-2 are communicated with the evaporator 1, and the other end is communicated with the mixing cavity 4-3. The cavity of the mixing cavity 4-3 is a tapered-divergent structure. The distance of 1-2mm is reserved between the inlet and the outlet of the flow channel after the laser cutting is finished and the edge of the steel plate, so that the connecting and positioning effects are achieved; the runner plate is connected with the upper cover plate and the lower cover plate through solid-state diffusion welding or instantaneous liquid-phase diffusion welding, holes are machined in the side face of the ejector 4 after welding is completed, and the runner plate is connected with other parts through pipelines. The ejector 4 may be located inside or outside the housing of the electronic product.
The capillary core 1-2 is a stainless steel sintered felt with a modified surface. The manufacturing method of the capillary core 1-2 comprises the following steps: selecting stainless steel fiber with the wire diameter of 10-60 μm produced by drawing as a raw material, uniformly laying the stainless steel fiber in a nickel-based alloy die, applying the pressure of 1-2MPa to the stainless steel fiber, and putting the stainless steel fiber and the die into a sintering furnace together. Heating to the temperature of 700 ℃ and 900 ℃, preserving the heat for 40-60min, and then cooling to the room temperature to finish the sintering of the stainless steel fiber, thereby obtaining the flexible porous stainless steel sintered felt with the thickness of 0.6-1 mm. In the sintering process, the sintering furnace is kept in vacuum or argon is introduced to be used as protective gas so as to prevent the stainless steel fiber from being oxidized and decarburized; then the stainless steel sintered felt is washed by acetone, absolute ethyl alcohol and deionized water in sequence and then soaked in 1mol/L hydrochloric acid and 1mol/L CuCl2Taking out the solution prepared by the molar ratio of 1:1 for 60-90s, and drying to obtain the super-hydrophilic surface modified sintered felt; and then cutting the sintered felt with the modified surface into a rectangle, cutting two adjacent corners of the rectangle into 2 squares with the same size, and folding the squares to form liquid absorption frames 1-6 on three side edges of the capillary core 1-2 so as to ensure that the liquid absorption frames 1-6 extend into the liquid in the compensation cavities 1-5.
According to the invention, the ejector 4 is added, so that the adverse effect of the lateral heat conduction of the evaporator bottom plate 1-1 is weakened, and the drying of the capillary core 1-2 is delayed. The modified flexible stainless steel sintered felt is used as the capillary core 1-2, so that the thickness is reduced, the impact resistance is good, the contact thermal resistance is reduced, the liquid absorption area is increased, and the upper limit of the power of the ultrathin flat plate type loop heat pipe is improved.
The working principle of the invention is as follows:
the lower part of the steam channel 1-4 is attached to a heat dissipation object, most of heat of the heat dissipation object reaches the lower surface of the capillary core 1-2, after a certain temperature, the liquid working medium on the lower surface of the capillary core 1-2 starts to evaporate to generate steam, and the steam enters the steam pipeline 3 along the steam channel 1-4. Meanwhile, the lateral heat conduction of the evaporator bottom plate 1-1 enables the temperature of the liquid working medium in the compensation cavity 1-5 to be continuously increased, and even bubbles are generated. The steam in the steam pipeline 3 enters the steam nozzle 4-2 of the ejector, is accelerated to reduce pressure in the steam pipeline, and forms a low-pressure area at the outlet of the steam nozzle 4-2. When the steam flow rate in the steam nozzle 4-2 is large enough, the ejector 4 starts to work, and the hot liquid/steam-liquid mixture in the compensation cavity 1-5 flows out of the compensation cavity 1-5 under the action of the pressure difference generated by the ejector 4 and enters the liquid nozzle 4-1 of the ejector through the liquid pipeline 2. Working media from the liquid nozzle 4-1 and the steam nozzle 4-2 are mixed in the mixing cavity 4-3 and then enter the cooler 6 through the first connecting pipeline 5, and the cooled working media return to the compensation cavity 1-5 through the second connecting pipeline 7. Most of the low-temperature liquid flowing into the compensation cavity 1-5 passes through the compensation cavity 1-5 under the action of the ejector 4 and then enters the ejector 4 from the liquid pipeline 2, and only a small part of the low-temperature liquid passes through the capillary core 1-2 under the action of capillary force and reaches the lower surface of the capillary core 1-2 for evaporation and heat exchange. Through the circulation flow of the working medium in the loop heat pipe, heat is continuously transferred from the heat dissipation object to the cooler 6 and then further transferred to the atmosphere or cooling water. After the ejector 4 is coupled, the low-temperature liquid effectively cools the compensation cavity 1-5 in the process of passing through the compensation cavity 1-5, bubbles generated in the compensation cavity 1-5 due to lateral heat conduction of the evaporator bottom plate 1-1 are taken away, the adverse effect of the lateral heat conduction of the evaporator bottom plate 1-1 on liquid supplement of the capillary core 1-2 is weakened, the drying of the capillary core is delayed, and the power upper limit of the ultrathin flat plate type loop heat pipe is improved.

Claims (10)

1. An ultrathin flat-plate loop heat pipe coupled with an ejector is characterized by comprising an evaporator (1), an ejector (4) and a cooler (6); wherein the evaporator (1) is connected with the ejector (4), and the ejector (4) is connected with the evaporator (1) through the cooler (6);
the evaporator (1) comprises an evaporator bottom plate (1-1), a capillary core (1-2) and an evaporator cover plate (1-3), a cavity formed by sealing the evaporator bottom plate (1-1) and the evaporator cover plate (1-3) is a compensation cavity (1-5), a plurality of steam channels (1-4) are arranged on the evaporator bottom plate (1-1), and the capillary core (1-2) is arranged on the steam channels (1-4); liquid absorbing frames (1-6) are arranged on three side edges of the capillary core (1-2), the bottoms of the liquid absorbing frames (1-6) are immersed in liquid in the compensation cavities (1-5), and the compensation cavities (1-5) are connected with the ejector (4) through the liquid pipeline (2).
2. The ultra-thin flat plate type loop heat pipe of the coupling ejector according to claim 1, wherein the ejector (4) comprises three layers of stainless steel plates which are attached together, the middle layer of stainless steel plate is a runner plate, a flow channel is formed on the runner plate, one end of the flow channel is communicated with the evaporator (1), and the other end of the flow channel is communicated with the cooler (6).
3. The ultrathin flat plate type loop heat pipe of the coupling ejector according to claim 2, wherein the three layers of stainless steel plates are attached by adopting a solid state diffusion welding method or an instantaneous liquid phase diffusion welding method;
the flow channel comprises a liquid nozzle (4-1), a steam nozzle (4-2) and a mixing cavity (4-3), the two sides of the steam nozzle (4-2) are respectively provided with the liquid nozzle (4-1), one end of the liquid nozzle (4-1) and one end of the steam nozzle (4-2) are communicated with the evaporator (1), and the other end of the liquid nozzle (4-1) and one end of the steam nozzle (4-2) are communicated with the mixing cavity (4-3).
4. The ultra-thin flat plate type loop heat pipe coupled with the ejector according to claim 2, wherein the steam nozzle (4-2) is a flow channel with a tapered or tapered-diverging structure, and the cavity of the mixing cavity (4-3) is of a tapered-diverging structure; the thickness of the flow channel plate is 1-1.5mm, and the flow channel is processed by a laser cutting method.
5. The ultra-thin flat loop heat pipe coupled with the ejector according to claim 1, wherein the steam channels (1-4) are connected with the ejector (4); the liquid pipeline (2) is a square pipe, and the steam pipeline (3) is a square pipe or a flat pipe; the flow area of the steam pipeline (3) is larger than that of the liquid pipeline (2).
6. The ultra-thin flat loop heat pipe for coupling an ejector according to claim 1, wherein the capillary wick (1-2) is prepared by: uniformly paving stainless steel fibers in a nickel-based alloy die, applying pressure of 1-2MPa to the stainless steel fibers through the nickel-based alloy die, preserving heat at the temperature of 700-900 ℃ for 40-60min, and cooling to room temperature to obtain a flexible porous stainless steel sintered felt; then soaking the stainless steel sintered felt in acidic CuCl2In the solution, a capillary core (1-2) is obtained.
7. The ultra-thin flat plate type loop heat pipe of claim 6, wherein the stainless steel fiber has a filament diameter of 10-60 μm.
8. The ultra-thin flat plate type loop heat pipe coupled with the ejector according to claim 6, wherein the thickness of the flexible porous stainless steel sintered felt is 0.6-1 mm.
9. The ultra-thin flat plate loop heat pipe of claim 6, wherein the acidic CuCl is2The solution is prepared by mixing 1mol/L hydrochloric acid and 1mol/L CuCl2The solution is prepared according to the molar ratio of 1:1, and the soaking time is 60-90 s.
10. The ultra-thin flat-plate loop heat pipe coupled with the ejector according to claim 1, wherein the cooler (6) is a fin-tube type air-cooled or a sleeve-tube type water-cooled cooler; the liquid suction frame (1-6) and the capillary core (1-2) are of an integral structure and are made of the same material.
CN202011053110.6A 2020-09-29 2020-09-29 Ultrathin flat-plate loop heat pipe of coupling ejector Pending CN112179190A (en)

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
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CN116336847A (en) * 2023-03-21 2023-06-27 山东大学 Loop heat pipe and manufacturing method thereof
CN116336847B (en) * 2023-03-21 2024-02-23 山东大学 Loop heat pipe and manufacturing method thereof

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