WO2021097974A1

WO2021097974A1 - Pulsating heat pipe taking liquid metal micro-nano liquid drops as working medium

Info

Publication number: WO2021097974A1
Application number: PCT/CN2019/125859
Authority: WO
Inventors: 郝婷婷; 马学虎; 杨思艳; 崔文宇; 陈彦松; 白涛; 兰忠
Original assignee: 大连理工大学
Priority date: 2019-11-19
Filing date: 2019-12-17
Publication date: 2021-05-27
Also published as: CN110779363A; CN110779363B

Abstract

The present invention provides a pulsating heat pipe taking liquid metal micro-nano liquid drops as a working medium, comprising a pulsating heat pipe body. The working medium of the pulsating heat pipe body is a mixed working medium mainly composed of liquid metal and a surfactant solution, the liquid metal is wrapped by the surfactant, an evaporation section of the pulsating heat pipe body generates a large number of tiny bubbles under a heating condition, the liquid metal is dispersed into multiple liquid metal liquid drops having a micro-nano scale by the generated bubbles, the liquid metal liquid drops are dispersed in the surfactant solution, the liquid metal liquid drops are spontaneously generated in the operation phase of the pulsating heat pipe body, and the liquid metal liquid drops are millimeter-scale liquid drops, micron-scale liquid drops, and nanometer-scale liquid drops. According to the pulsating heat pipe of the present invention, the characteristics such as local microconvection can be generated by combining the ultrahigh heat conductivity of the liquid metal and the liquid metal micro-nano liquid drops, and the heat transfer performance and heat load bearing capability of the pulsating heat pipe can be significantly improved.

Description

Pulsating heat pipe with liquid metal micro-nano droplets as working fluid

Technical field

The invention relates to the technical field of pulsating heat pipe research, in particular, to a pulsating heat pipe with liquid metal micro-nano droplets as a working medium, which is applied to the technical fields of high-efficiency heat dissipation of electronic components, industrial waste heat recovery and process heat exchange.

Background technique

With the development of very large-scale integrated circuits, the local heat flux density gradually increases. If the heat can not be effectively dissipated in time, it will cause the chip temperature to be too high and cause performance degradation. Therefore, the heat dissipation with high heat flux density under the small size is the main bottleneck restricting the development of integrated circuits. The existing traditional methods for improving heat dissipation efficiency have almost reached the limit, and the lack of new effective heat dissipation methods has become one of the main bottlenecks restricting the development of new technologies. Therefore, it is very urgent and necessary to carry out research on efficient heat dissipation technology under high heat flux density. As a special member of the heat pipe family, the pulsating heat pipe has a completely different working mechanism from ordinary heat pipes and has many unique advantages. The pulsating heat pipe couples phase change heat transfer and convection heat transfer with two heat transfer methods, and the effective thermal conductivity is higher. , Has become one of the most promising technical solutions to the heat dissipation problem under high heat flux density in the future.

The heat transfer mode of the pulsating heat pipe is mainly the sensible heat transfer of the liquid bomb oscillating motion in the evaporation section and the condensing section. The nature of the working fluid and the flow state of the pulsating heat pipe significantly affect the heat transfer performance of the pulsating heat pipe. Choosing a working medium with high thermal conductivity will significantly improve the heat transfer performance of the pulsating heat pipe. Liquid metal (gallium and its alloys) is a special material that combines high thermal conductivity of metal with liquid fluidity. Its thermal conductivity is dozens of times that of water. In 2014, the National Aeronautics and Space Administration (NASA) put "liquid metal "Cooling" is listed as the frontier technology of the future. Studies have found that using liquid metal and water as working fluids of pulsating heat pipes, the heat transfer performance of pulsating heat pipes is significantly improved (see: Hao et al., Journal of Heat Transfer, 2019,141(7):071802). Liquid metal also has a unique property. Under the action of bubbles and surfactant solution, liquid metal gallium can be dispersed into liquid metal droplets with a size of tens of nanometers to thousands of microns, forming a kind of liquid metal micro-nano droplets. Pulsating heat pipe for working fluid. The surfactant adheres to the surface of the liquid metal droplet, making the liquid metal droplet more stable. Therefore, the invention of a pulsating heat pipe with liquid metal micro-nano droplet working fluid will provide a new idea and efficient solution for the rapid heat dissipation problem of high heat flux under small dimensions, and at the same time open up a new direction for the research of high-efficiency pulsating heat pipes .

Summary of the invention

According to the above proposal, with the development of very large scale integrated circuits, the local heat flux density gradually increases. Due to the inability to effectively dissipate heat in time, the chip temperature is too high and the performance decreases. The heat dissipation of the high heat flux density under the small size restricts the development of integrated circuit technology. The problem is to provide a pulsating heat pipe with liquid metal micro-nano droplets as the working fluid. The present invention mainly improves the heat transfer performance of the pulsating heat pipe through the liquid metal micro-nano drop working medium. The working medium of the traditional pulsating heat pipe mainly includes: water, ethanol, acetone and their mixtures, nanofluids and the like. The liquid metal is introduced into the working fluid, taking advantage of the ultra-high thermal conductivity of the liquid metal. At the same time, under the action of the surfactant, the liquid metal is dispersed into stable micro-nano droplets, and the liquid metal micro-nano droplets are used as the pulsation of the working fluid. Heat pipe, thereby significantly improving the heat transfer capacity and the ability of carrying heat load of the pulsating heat pipe.

The technical means adopted by the present invention are as follows:

A pulsating heat pipe with liquid metal micro-nano droplets as a working medium includes a pulsating heat pipe. The working medium of the pulsating heat pipe is a mixed working medium mainly composed of liquid metal and a surfactant solution. It consists of an active agent and water, the liquid metal is coated by the surfactant, wherein the evaporation section of the pulsating heat pipe generates a large number of tiny bubbles under heating, and the liquid metal is dispersed into a plurality of bubbles by the generated bubbles Liquid metal droplets with micro-nano scale, the liquid metal droplets are dispersed in the surfactant solution, the presence of the surfactant reduces the surface tension of the solution, so that the liquid metal droplets are not easy to merge and form a stable Existing micro-nano droplets; the liquid metal droplets are spontaneously generated during the operation phase of the pulsating heat pipe, and the pulsating heat pipe can make the liquid metal droplets move spontaneously under the pressure difference of phase change heat transfer; the liquid metal liquid Drops include millimeter-scale droplets, micro-scale droplets, and nano-scale droplets, and the size distribution of the liquid metal droplets ranges from millimeter-scale to nano-scale.

Further, the size of the liquid metal droplets has a certain distribution range, and the millimeter-level droplets, the micron-level droplets, and the nano-level droplets coexist or the micron-level droplets and the nano-level droplets coexist.

Further, the liquid metal is one of gallium, indium, or tin that is liquid at a temperature of 20°C to 50°C, or a combination of more than one form. That is, the liquid metal is a metal element or a metal mixture that is liquid at a temperature of 20°C-50°C, the metal element is one of gallium, indium or tin, and the metal mixture is at least two of gallium, indium or tin. Alloys of various metals.

Further, the surfactant is at least one of anionic surfactants, cationic surfactants or nonionic surfactants, or a combination of more than one; the anionic surfactants contain 8-16 Carbon atom alkyl sulfate, or alkyl sulfonate containing 8-16 carbon atoms, or alkylbenzene sulfonate containing 8-16 carbon atoms; the cationic surfactant contains 8-18 Alkyl dimethylamine oxide with three carbon atoms; the non-ionic surfactant is one of polyethylene glycol or polyethylene glycol octyl phenyl ether, or a combination of more than one form, wherein the The molecular weight of the polyethylene glycol is 2000-10000.

Further, the pulsating heat pipe working medium is a mixed working medium of liquid metal and a surfactant solution, the liquid metal is dispersed into micro-nano droplets, the liquid metal is the dispersed phase of the mixed working medium, and the surfactant solution is the continuous working medium of the mixed working medium. Phase, during the operation phase of the pulsating heat pipe, the liquid metal micro-nano droplets are dispersed in the surfactant solution, and the liquid metal is coated with the surfactant. With the addition of surfactants, the surface tension of the continuous phase is significantly reduced, which can effectively enhance the wetting performance of the working fluid in the pulsating heat pipe. The added surfactant can adhere to the surface of the liquid metal micro-nano droplets to ensure the long-term stable existence of the liquid metal micro-nano droplets.

Further, the liquid metal droplets will form a local oscillating motion during the process of flowing with the fluid to form a local micro-convection, which further improves the heat transfer capability of the working fluid.

Further, the liquid metal droplet pulsating heat pipe combines the advantages of the heat conduction of liquid metal and water. The liquid metal transfers heat mainly by heat conduction, and the water transfers heat mainly by convection. The pulsating heat pipe couples the heat transfer advantages of two fluids. Compared with the ordinary working fluid pulsating heat pipe, the heat transfer performance of the liquid metal micro-nano droplet pulsating heat pipe is significantly improved.

Further, the number of bends of the pulsating heat pipe is greater than or equal to 6.

Further, the angle between the operation direction of the pulsating heat pipe and the horizontal direction is 0°-90°.

Further, the heating mode of the pulsating heat pipe is related to the number of elbows of the pulsating heat pipe. When the number of bends of the pulsating heat pipe is 6-12, the angle range between the operating direction of the pulsating heat pipe and the horizontal direction is 10°-90° (the angle between 90° and the horizontal direction is the vertical bottom heating direction); When the number is 13 and above, the range of the angle between the operating direction of the pulsating heat pipe and the horizontal direction is 0°-90°.

Further, the substrate of the pulsating heat pipe is copper, stainless steel or Teflon material.

Further, the substrate of the pulsating heat pipe is red copper, stainless steel or Teflon plate type pulsating heat pipe, and the passage of the pulsating heat pipe is processed by mechanical processing. During the stable operation stage of the pulsating heat pipe, the motion law and size distribution of the liquid metal droplets in the pulsating heat pipe are observed by high-speed cameras, and the size distribution results of the droplets are obtained by analysis and processing. Due to the pixel limitation of the captured pictures, the pictures captured by the high-speed camera only count the micron-level liquid metal droplets with a diameter greater than 50μm. After the experiment, the working fluid of the pulsating heat pipe was tested and analyzed in detail, and the size distribution of the liquid metal nanodroplets in the working fluid was analyzed by a nanoparticle size potentiometer.

Further, the total volume filling rate of the mixed working fluid of the pulsating heat pipe ranges from 30% to 80%, wherein the mass fraction of the liquid metal in the mixed working fluid is 10% to 60%, and the surface The mass fraction of the active agent solution is 40% to 90%, and the mass concentration of the surfactant in the surfactant solution is 0.01% to 5%.

Further, the working temperature range of the pulsating heat pipe is 30°C-100°C.

Further, the hydraulic diameter of the pulsating heat pipe is 2mm-4mm; the shape of the channel in the pulsating heat pipe is rectangular, square or circular.

Further, the size of the liquid metal droplet is closely related to the working temperature, input power, and the type and concentration of surfactants of the pulsating heat pipe. The type, concentration, and heating power of the surfactant can be adjusted to adjust the size of the liquid metal droplet. The size distribution improves the cooling temperature control ability of the pulsating heat pipe.

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

1. The pulsating heat pipe with liquid metal micro-nano droplets as the working fluid provided by the present invention improves the heat transfer performance of the pulsating heat pipe through the liquid metal micro-nano droplet working fluid. The working fluids of the traditional pulsating heat pipe mainly include: water, ethanol, acetone And its mixtures and nanofluids, etc. The liquid metal is introduced into the working fluid, taking advantage of the ultra-high thermal conductivity of the liquid metal. At the same time, under the action of the surfactant, the liquid metal is dispersed into stable micro-nano droplets, and the liquid metal micro-nano droplets are used as the pulsation of the working fluid. Heat pipe, thereby significantly improving the heat transfer capacity and the ability of carrying heat load of the pulsating heat pipe.

2. The present invention provides a pulsating heat pipe with liquid metal micro-nano droplets as the working fluid. The liquid metal micro-nano droplets can be automatically generated in the pulsating heat pipe, and the liquid metal can be adjusted by adjusting the type, concentration and heating power of the surfactant The droplet size distribution improves the cooling temperature control ability of the pulsating heat pipe.

3. The present invention provides a pulsating heat pipe with liquid metal micro-nano droplets as a working fluid. The working fluid of the pulsating heat pipe is a mixed working fluid of liquid metal and a surfactant solution. The thermal conductivity of liquid metal is tens or even a few of that of ordinary working fluids. Hundred times, can effectively improve the thermal conductivity of the pulsating heat pipe working fluid.

4. The present invention provides a pulsating heat pipe with liquid metal micro-nano droplets as the working medium, the pulsating heat pipe working medium is a mixed working medium of liquid metal and a surfactant solution, the liquid metal is dispersed into micro-nano droplets, and the liquid metal is the dispersed phase. The surfactant solution is a continuous phase, and when surfactant is added, the surface tension of the continuous phase is significantly reduced, which can effectively enhance the wetting performance of the working fluid in the pulsating heat pipe. The added surfactant can adhere to the surface of the liquid metal micro-nano droplets to ensure the long-term stable existence of the liquid metal micro-nano droplets.

5. The present invention provides a pulsating heat pipe with liquid metal micro-nano droplets as a working fluid. The liquid metal micro-nano droplets will form a local oscillating motion when flowing with the fluid, forming local micro-convection, and further improve the heat transfer capacity of the working fluid. .

6. The present invention provides a pulsating heat pipe with liquid metal micro-nano droplets as a working medium. The liquid metal micro-nano droplet pulsating heat pipe combines the advantages of liquid metal and water in the heat conduction of two fluids. The liquid metal mainly transfers heat by means of heat conduction. Water transfers heat mainly by convection. The pulsating heat pipe couples the heat transfer advantages of the two fluids. Compared with the ordinary working fluid pulsating heat pipe, the heat transfer performance of the liquid metal micro-nano droplet pulsating heat pipe is significantly improved.

In summary, the application of the technical solution of the present invention can solve the problem of the gradual increase in local heat flux density in the prior art with the development of very large scale integrated circuits. Due to the inability to effectively dissipate heat in time, the chip temperature is too high and the performance is reduced. The heat dissipation of high heat flux has restricted the development of integrated circuits.

Based on the above reasons, the present invention can be widely promoted in the fields of microelectronic chip heat dissipation and cooling, industrial waste heat recovery, and process heat exchange under high heat flux using pulsating heat pipes to transfer heat.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor.

Fig. 1 is a schematic diagram of the liquid metal micro-nano droplet pulsating heat pipe in operation of the present invention.

Figure 2 is an effect diagram of the liquid metal micro-nano droplet pulsating heat pipe in operation of the present invention.

Fig. 3 is a size distribution diagram of liquid metal micro-nano droplets when the pulsating heat pipe in the present invention operates in a steady state.

Fig. 4 is a size distribution diagram of liquid metal micro-nano droplets when the pulsating heat pipe in the present invention operates in a steady state.

Fig. 5 is a size distribution diagram of liquid metal micro-nano droplets when the pulsating heat pipe in the present invention operates in a steady state.

Fig. 6 is a diagram showing the size distribution of liquid metal droplets of a liquid metal micro-nano droplet pulsating heat pipe under different heating powers in the present invention.

Fig. 7 is an effect diagram of liquid metal droplets under different heating powers of a liquid metal micro-nano droplet pulsating heat pipe in the present invention.

Fig. 8 is a droplet size distribution diagram of a liquid metal micro-nano droplet pulsating heat pipe in the present invention under different surfactant concentrations.

Fig. 9 is a size distribution diagram of liquid metal nanometer droplets in the working fluid in the pulsating heat pipe of the present invention.

10 is a comparison diagram of the thermal resistance of the liquid metal micro-nano droplet pulsating heat pipe and the pure water pulsating heat pipe under the same liquid filling rate in the present invention.

Fig. 11 is a heat transfer enhancement efficiency diagram of the liquid metal micro-nano droplet pulsating heat pipe of the present invention.

In the figure: 1. Liquid phase; 2. Liquid metal micro-nano droplets; 3. Bubbles.

Detailed ways

It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict. Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments.

In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative, and in no way serves as any limitation to the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

It should be noted that the terms used here are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and/or "including" are used in this specification, they indicate There are features, steps, operations, devices, components, and/or combinations thereof.

Unless specifically stated otherwise, the relative arrangement of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The technologies, methods, and equipment known to those of ordinary skill in the relevant fields may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be regarded as part of the authorization specification. In all the examples shown and discussed herein, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiment may have different values. It should be noted that similar reference numerals and letters indicate similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

In the description of the present invention, it needs to be understood that orientation words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom", etc. indicate the orientation Or positional relationship is usually based on the position or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description. Unless otherwise stated, these positional words do not indicate or imply the pointed device or element It must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as a limitation of the protection scope of the present invention: the orientation word "inside and outside" refers to the inside and outside relative to the contour of each component itself.

For ease of description, spatially relative terms can be used here, such as "above", "above", "above the surface", "above", etc., to describe as shown in the figure Shows the spatial positional relationship between one device or feature and other devices or features. It should be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation of the device described in the figure. For example, if the device in the drawing is turned upside down, then a device described as "above other devices or structures" or "above other devices or structures" will then be positioned as "below the other devices or structures" or "on It's under the device or structure". Thus, the exemplary term "above" can include both orientations "above" and "below". The device can also be positioned in other different ways (rotated by 90 degrees or in other orientations), and the relative description of the space used here will be explained accordingly.

In addition, it should be noted that the use of terms such as “first” and “second” to define parts is only for the convenience of distinguishing the corresponding parts. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood. To limit the scope of protection of the present invention.

As shown in Figure 1-2, the present invention provides a pulsating heat pipe with liquid metal micro-nano droplets as a working medium, including a pulsating heat pipe. The working medium of the pulsating heat pipe includes but not limited to surfactant solution and liquid metal or A mixed working medium of an alloy of liquid metal, the surfactant solution is composed of a surfactant and water, the liquid metal is coated by the surfactant, and the evaporation section of the pulsating heat pipe is heated, A large number of tiny bubbles 3 are generated, and the liquid metal is dispersed into a plurality of liquid metal droplets with a micro-nano scale by the generated bubbles 3, and the liquid metal droplets are dispersed in the surfactant solution. The presence of, reduces the surface tension of the solution, makes the liquid metal droplets difficult to merge, forming stable micro-nano droplets; the liquid metal droplets are spontaneously generated during the operation phase of the pulsating heat pipe, and the pulsating heat pipe can make the liquid metal droplets Spontaneous movement is realized under the pressure difference of phase change heat transfer; the liquid metal droplets include millimeter-level droplets, micron-level droplets and nano-level droplets, and the size distribution of the liquid metal droplets ranges from millimeter-level to nanometer level. level.

The size of the liquid metal droplets has a certain distribution range, and the millimeter-level droplets, the micron-level droplets and the nano-level droplets coexist or the micron-level droplets and the nano-level droplets coexist.

The liquid metal is one of gallium, indium, or tin that is liquid at a temperature of 20°C to 50°C, or a combination of more than one form. That is, the liquid metal is a metal element or a metal mixture that is liquid at a temperature of 20°C-50°C. The metal element includes but is not limited to gallium, indium, and tin, and the metal mixture includes, but is not limited to, gallium, indium, and tin. In an alloy of at least two metals.

The surfactant is at least one of anionic surfactants, cationic surfactants or nonionic surfactants, or a combination of more than one; the anionic surfactants include, but are not limited to, 8-16 Carbon atom alkyl sulfate, or alkyl sulfonate containing 8-16 carbon atoms, or alkylbenzene sulfonate containing 8-16 carbon atoms; the cationic surfactants include but are not limited to Alkyl dimethylamine oxides with 8-18 carbon atoms; the non-ionic surfactants include but are not limited to polyethylene glycol, polyethylene glycol octyl phenyl ether and mixtures thereof, wherein the poly The molecular weight of ethylene glycol is 2000-10000.

The pulsating heat pipe working medium is a mixed working medium of liquid metal and a surfactant solution, the liquid metal is dispersed into micro-nano droplets, the liquid metal is the dispersed phase of the mixed working medium, and the surfactant solution is the continuous phase of the mixed working medium. During the operation phase of the pulsating heat pipe, the liquid metal micro-nano droplets 2 are dispersed in the surfactant solution, and the liquid metal is coated with the surfactant. With the addition of surfactants, the surface tension of the continuous phase is significantly reduced, which can effectively enhance the wetting performance of the working fluid in the pulsating heat pipe. The added surfactant can adhere to the surface of the liquid metal micro-nano droplets 2 to ensure the long-term stable existence of the liquid metal micro-nano droplets 2.

The liquid metal droplets will form a local oscillating motion during the process of flowing with the fluid, forming local micro-convection, and further improving the heat transfer capability of the working fluid.

The liquid metal droplet pulsating heat pipe combines the advantages of the heat conduction of liquid metal and water. The liquid metal transfers heat mainly by heat conduction, and the water transfers heat mainly by convection. The pulsating heat pipe couples the heat transfer advantages of two fluids. Compared with the ordinary working fluid pulsating heat pipe, the heat transfer performance of the liquid metal micro-nano droplet pulsating heat pipe is significantly improved.

The number of bends of the pulsating heat pipe is greater than or equal to 6.

The angle between the operation direction of the pulsating heat pipe and the horizontal direction is 0°-90°.

The heating mode of the pulsating heat pipe is related to the number of elbows of the pulsating heat pipe. When the number of bends of the pulsating heat pipe is 6-12, the angle range between the operating direction of the pulsating heat pipe and the horizontal direction is 10°-90° (the angle between 90° and the horizontal direction is the vertical bottom heating direction); When the number is 13 and above, the range of the angle between the operating direction of the pulsating heat pipe and the horizontal direction is 0°-90°.

The substrate of the pulsating heat pipe is copper, stainless steel or Teflon material.

The substrate of the pulsating heat pipe is red copper, stainless steel or Teflon plate type pulsating heat pipe, and the channel of the pulsating heat pipe is processed by mechanical processing. In the stable operation stage of the pulsating heat pipe, the movement law and size distribution of the liquid metal droplets in the pulsating heat pipe are observed by a high-speed camera, and the size distribution results of the droplets are analyzed and processed. Among them, the high-speed camera uses the Japanese Photron Fastcam Apx-Rs. Due to the pixel limit of the captured pictures, the pictures captured by the high-speed camera only count the micron-level liquid metal droplets with a diameter greater than 50μm. After the experiment, the working fluid of the pulsating heat pipe was tested and analyzed in detail, and the size distribution of the liquid metal nanodroplets in the working fluid was analyzed by a nano-particle size potentiometer. The nano-particle size potentiometer used the American Malvern Zetasizer Nano ZS90.

The total volume filling rate of the pulsating heat pipe mixed working fluid ranges from 30% to 80%, wherein the mass fraction of the liquid metal in the mixed working fluid is 10% to 60%, and the surfactant solution The mass fraction is 40%-90%, and the mass concentration of the surfactant in the surfactant solution is 0.01%-5%.

The working temperature range of the pulsating heat pipe is 30°C-100°C.

The hydraulic diameter of the pulsating heat pipe is 2mm-4mm; the shape of the channel in the pulsating heat pipe is rectangular, square or circular.

The size of the liquid metal droplet is closely related to the working temperature, input power, and the type and concentration of the surfactant. The size distribution of the liquid metal droplet can be adjusted by adjusting the type, concentration and heating power of the surfactant. Improve the cooling temperature control ability of the pulsating heat pipe.

Example 1

As shown in Figure 1, it is a schematic diagram of the liquid metal micro-nano droplet pulsating heat pipe during operation. As shown in Figure 2, the effect diagram of the liquid metal micro-nano droplet pulsating heat pipe during operation. The substrate of the pulsating heat pipe in the picture is copper, the number of elbows is 6, the angle between the operating direction and the horizontal direction is 90°, that is, the pulsating heat pipe is a vertical bottom heating method, and the cross-sectional shape of the pulsating heat pipe channel is square, and the The hydraulic diameter is 3mm. The working medium of the pulsating heat pipe is gallium tin indium alloy (the mass fractions of gallium, indium and tin in the gallium tin indium alloy are 68.5%, 21.5% and 10% respectively) and sodium dodecylbenzene sulfonate anionic surfactant solution . The total volume filling rate of the pulsating heat pipe mixed working fluid is 70%, of which the liquid metal filling in the mixed working fluid accounts for 20% (mass fraction) of the total working fluid filling capacity, and the surfactant solution accounts for 80% %, the mass concentration of the surfactant in the surfactant solution is 0.4%, and the heating power is 340W. It can be seen from Figure 1 and Figure 2 that a large number of small bubbles 3 are generated in the evaporation section, and the liquid metal is dispersed into a number of micro-nano-scale droplets by the generated bubbles 3. Due to the presence of surfactants, the generated small bubbles 3 and liquid metal micro-nano The droplet 2 exists stably in the liquid phase 1.

Example 2

In order to analyze the size distribution of liquid metal droplets in detail, the pulsating heat pipe is visualized experimentally. In the stable operation stage of the pulsating heat pipe, the movement law and size distribution of the liquid metal droplets in the pulsating heat pipe are observed by a high-speed camera, and the size distribution results of the droplets are analyzed and processed. Among them, the high-speed camera uses the Japanese Photron Fastcam Apx-Rs. Due to the pixel limitation of the captured pictures, the pictures captured by the high-speed camera only count the micron-level liquid metal droplets with a diameter greater than 50μm. After the experiment, the working fluid of the pulsating heat pipe was tested and analyzed in detail, and the size distribution of the liquid metal nanodroplets in the working fluid was analyzed by a nano-particle size potentiometer. The nano-particle size potentiometer used the British Malvern Zetasizer Nano ZS90.

As shown in FIG. 3, in this embodiment, the working medium of the pulsating heat pipe is a mixed working medium of liquid metal and a surfactant solution. During the operation of the pulsating heat pipe, the liquid metal is automatically dispersed into micro-nano-scale liquid metal droplets. Among them, the substrate of the pulsating heat pipe is copper, the number of elbows is 6, the angle between the operation direction and the horizontal direction is 90°, the cross-sectional shape of the pulsating heat pipe channel is square, and the hydraulic diameter of the channel is 3mm. The working medium of the pulsating heat pipe is gallium tin indium alloy (the mass fractions of gallium, indium and tin in the gallium tin indium alloy are 68.5%, 21.5% and 10% respectively) and sodium dodecylbenzene sulfonate anionic surfactant solution . The total volume filling rate of the pulsating heat pipe mixed working fluid is 70%, of which the liquid metal filling in the mixed working fluid accounts for 20% (mass fraction) of the total working fluid filling capacity, and the surfactant solution accounts for 80% %, the mass concentration of the surfactant in the surfactant solution is 0.4%. It can be seen from Figure 3 that when the heating power of the pulsating heat pipe is 260W, the statistical results of the size distribution of the liquid metal droplets show that the radius of the liquid metal droplets ranges from 0.2mm to 1.1mm, and the average radius is 0.6mm.

Example 3

As shown in Figure 4, in this embodiment, the substrate of the pulsating heat pipe is copper, the number of elbows is 6, the angle between the operation direction and the horizontal direction is 90°, the cross-sectional shape of the pulsating heat pipe is square, and the channel The hydraulic diameter is 3mm. The working medium of the pulsating heat pipe is gallium tin indium alloy (the mass fractions of gallium, indium and tin in the gallium tin indium alloy are 68.5%, 21.5% and 10% respectively) and sodium dodecylbenzene sulfonate anionic surfactant solution . The total volume filling rate of the pulsating heat pipe mixed working fluid is 70%, of which the liquid metal filling in the mixed working fluid accounts for 20% (mass fraction) of the total working fluid filling capacity, and the surfactant solution accounts for 80% %, the mass concentration of the surfactant in the surfactant solution is 0.4%. It can be seen from Figure 4 that when the heating power of the pulsating heat pipe is 340W, the statistical results of the size distribution of the liquid metal droplets show that the radius of the liquid metal droplets ranges from 0.1mm to 0.5mm, and the average radius is 0.3mm.

Example 4

As shown in Figure 5, in this embodiment, the substrate of the pulsating heat pipe is copper, the number of elbows is 6, the angle between the operating direction and the horizontal direction is 90°, the cross-sectional shape of the pulsating heat pipe is square, and the channel The hydraulic diameter is 3mm. The working medium of the pulsating heat pipe is gallium tin indium alloy (the mass fractions of gallium, indium and tin in the gallium tin indium alloy are 68.5%, 21.5% and 10% respectively) and sodium dodecylbenzene sulfonate anionic surfactant solution . The total volume filling rate of the mixed working fluid of the pulsating heat pipe is 70%, of which the filling amount of liquid metal accounts for 20% (mass fraction) of the total filling volume of the working fluid, and the surfactant solution accounts for 80% of the mass fraction. The surface activity The mass concentration of the surfactant in the agent solution is 2%. It can be seen from Figure 5 that when the heating power of the pulsating heat pipe is 340W, the statistical results of the size distribution of the liquid metal droplets show that the radius of the liquid metal droplets ranges from 0.2mm to 1mm, and the average radius is 0.4mm.

Example 5

In this embodiment, FIG. 6 is a liquid metal droplet size distribution diagram of a liquid metal micro/nano droplet pulsating heat pipe under different heating powers, and FIG. 7 is a liquid metal micro/nano droplet pulsating heat pipe under different heating powers The effect diagram of the liquid metal droplet, that is, the visual image of the corresponding liquid metal droplet, to investigate the influence of the heating power on the size of the liquid metal droplet. The substrate of the pulsating heat pipe is copper, the number of elbows is 6, the angle between the operation direction and the horizontal direction is 90°, the cross-sectional shape of the pulsating heat pipe channel is square, and the hydraulic diameter of the channel is 3mm. The working medium of the pulsating heat pipe is gallium tin indium alloy (the mass fractions of gallium, indium and tin in the gallium tin indium alloy are 68.5%, 21.5% and 10% respectively) and sodium dodecylbenzene sulfonate anionic surfactant solution . The total volume filling rate of the pulsating heat pipe mixed working fluid is 70%, of which the liquid metal filling in the mixed working fluid accounts for 20% (mass fraction) of the total working fluid filling capacity, and the surfactant solution accounts for 80% %, the mass concentration of the surfactant in the surfactant solution is 0.4%, and the heating power is 220W to 380W. It can be seen from Fig. 6 and Fig. 7 that with the increase of heating power, the number and frequency of bubbles 3 generated in the evaporation section increase, the severity of the bubbles 3 generated increases, the liquid metal is dispersed, the size of the droplets decreases, and the heating power increases. Above 300W, the liquid metal droplets with a radius greater than 1mm disappear, and the radius of the liquid metal droplets are all less than 1mm.

Example 6

In this embodiment, FIG. 8 is a droplet size distribution diagram of a liquid metal micro-nano droplet pulsating heat pipe under different surfactant concentrations to investigate the effect of surfactant concentration on liquid metal droplet size. The substrate of the pulsating heat pipe is copper, the number of elbows is 6, the angle between the operation direction and the horizontal direction is 90°, the cross-sectional shape of the pulsating heat pipe channel is square, and the hydraulic diameter of the channel is 3mm. The working medium of the pulsating heat pipe is gallium tin indium alloy (the mass fractions of gallium, indium and tin in the gallium tin indium alloy are 68.5%, 21.5% and 10% respectively) and sodium dodecylbenzene sulfonate anionic surfactant solution . The total volume filling rate of the pulsating heat pipe mixed working fluid is 70%, of which the liquid metal filling in the mixed working fluid accounts for 20% (mass fraction) of the total working fluid filling capacity, and the surfactant solution accounts for 80% %, the mass concentration of the surfactant in the surfactant solution is 0.4%-2%, and the heating power is 340W. It can be seen from Figure 8 that at this filling ratio of liquid metal, the size of liquid metal droplets first decreases and then increases, and there is an optimal surfactant concentration, and the optimal surfactant mass concentration is 0.4%-1% . When the surfactant concentration is low, there is less surfactant attached to the surface of the liquid metal droplets, the repulsive force between the droplets is reduced, the liquid metal droplets generated are easy to merge, and there are liquid metal droplets of larger size. When the surfactant concentration is high, the viscosity of the solution increases significantly, which is not conducive to the formation of bubbles 3 and the dispersion of liquid metal droplets.

Example 7

In this embodiment, FIG. 9 is a diagram of the size distribution of liquid metal nano-droplets in a pulsating heat pipe. The substrate of the pulsating heat pipe is copper, the number of elbows is 6, the angle between the operation direction and the horizontal direction is 90°, the cross-sectional shape of the pulsating heat pipe channel is square, and the hydraulic diameter of the channel is 3mm. The working medium of the pulsating heat pipe is pure gallium and sodium lauryl sulfate anionic surfactant solution. The total volume filling rate of the pulsating heat pipe mixed working fluid is 70%, of which the liquid metal filling in the mixed working fluid accounts for 20% (mass fraction) of the total working fluid filling capacity, and the surfactant solution accounts for 80% %, the mass concentration of the surfactant in the surfactant solution is 0.4%. The heating power of the pulsating heat pipe is 100W to 380W. It can be seen from Fig. 9 that with the operation of the pulsating heat pipe, the liquid metal gallium is dispersed into micron and nanometer-level gallium droplets, and the color of the mixed working fluid gradually changes from transparent to gray. Take out the working medium, analyze the formed nanofluid by a nanometer size potentiometer, and find that most of the nanometer gallium particles have a size distribution in the range of 100nm to 1000nm.

Example 8

In this embodiment, FIG. 10 is a comparison diagram of the thermal resistance of a liquid metal micro-nano droplet pulsating heat pipe and a pure water pulsating heat pipe under the same filling rate, that is, the thermal resistance of a liquid metal micro-nano particle pulsating heat pipe, and the working fluid is water. The thermal resistance of the pulsating heat pipe. The substrate of the pulsating heat pipe is copper, the number of elbows is 6, the angle between the operation direction and the horizontal direction is 90°, the cross-sectional shape of the pulsating heat pipe channel is square, and the hydraulic diameter of the channel is 3mm, the pure water pulsating heat pipe The filling rate is 70%. The working medium of the liquid metal micro-nano droplet pulsating heat pipe is gallium tin indium alloy (the mass fractions of gallium, indium, and tin in the gallium tin indium alloy are 68.5%, 21.5% and 10% respectively) and dodecyl benzene sulfonic acid Sodium anionic surfactant solution. The total volume filling rate of the pulsating heat pipe mixed working fluid is 70%, of which the liquid metal filling in the mixed working fluid accounts for 20% (mass fraction) of the total working fluid filling capacity, and the surfactant solution accounts for 80% %, the mass concentration of the surfactant in the surfactant solution is 0.4%. The heating power starts from 100W. After the pulsating heat pipe runs stably for 20 minutes, the heating power is increased by 40W each time until the pulsating heat pipe’s evaporation section The average temperature reaches 100°C, and the temperature of the evaporation section of the pulsating heat pipe is 100°C, which is defined as the heat load of the pulsating heat pipe. It can be seen from Figure 10 that with the increase of heating power, the thermal resistance of the two pulsating heat pipes shows a decreasing trend. Under the same heating power, compared with the pulsating heat pipe whose working fluid is water, the liquid metal micro-nano droplet pulsating heat pipe The thermal resistance is significantly reduced, and the thermal load of the liquid metal micro-nano droplet pulsating heat pipe is increased. The heat load of the pulsating heat pipe with water as the working fluid is 340W, while the heat load of the liquid metal micro-nano droplet pulsating heat pipe is 380W.

Example 9

In this embodiment, FIG. 11 is a heat transfer enhancement efficiency diagram of the liquid metal micro-nano droplet pulsating heat pipe, that is, the performance comparison of the liquid metal micro-nano droplet pulsating heat pipe and the pulsating heat pipe whose working fluid is pure water. The experimental conditions of the pulsating heat pipe are the same as in Example 8. The heat transfer enhancement efficiency is defined as:

Among them, η is the enhancement efficiency of heat transfer,

Is the thermal resistance of the pure water pulsating heat pipe,

It is the thermal resistance of the liquid metal pulsating heat pipe.

It can be seen from FIG. 11 that as the heating power increases, the size of the liquid metal micro-nano droplets 2 gradually decreases, and the distribution becomes more uniform. As the size of the liquid metal droplet decreases, the heat transfer enhancement efficiency of the pulsating heat pipe increases. When the heating power is more than 300W, compared with the pure water pulsating heat pipe with the same filling rate, the liquid metal micro-nano droplet pulsates The heat transfer performance of the heat pipe is increased by 20%-25%.

The embodiments of the present invention are not limited by the above-mentioned embodiments, wherein the size distribution of the liquid metal micro/nano droplets 2 can be adjusted by the type of surfactant, the concentration of the surfactant, the heating power and the operation mode.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. range.

Claims

A pulsating heat pipe with liquid metal micro-nano droplets as a working fluid is characterized by comprising a pulsating heat pipe. The working fluid of the pulsating heat pipe is a mixed working fluid mainly composed of liquid metal and a surfactant solution. The surface active The agent solution is composed of a surfactant and water. The liquid metal is coated by the surfactant. The evaporation section of the pulsating heat pipe generates a large number of tiny bubbles under heating. The liquid metal is generated by the bubbles. Dispersed into a plurality of liquid metal droplets with micro-nano scale, the liquid metal droplets are dispersed in the surfactant solution, and the liquid metal droplets are spontaneously generated during the operation phase of the pulsating heat pipe; the liquid metal The droplets include millimeter-level droplets, micron-level droplets, and nano-level droplets.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 1, wherein the size of the liquid metal droplets has a certain distribution range, and the millimeter-level droplets, the micron-level droplets and the nano-level droplets have a certain distribution range. The droplets are present at the same time or the micron-level droplets and the nano-level droplets are present at the same time.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 1, wherein the liquid metal is one of gallium, indium, or tin that is liquid at a temperature of 20°C-50°C , Or a combination of more than one form.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 1, wherein the surfactant is at least one of anionic surfactants, cationic surfactants or nonionic surfactants , Or a combination of more than one form; the anionic surfactant is an alkyl sulfate containing 8-16 carbon atoms, or an alkyl sulfonate containing 8-16 carbon atoms, or containing 8-16 Carbon atom alkylbenzene sulfonate; the cationic surfactant is an alkyl dimethylamine oxide containing 8-18 carbon atoms; the nonionic surfactant is polyethylene glycol or polyethylene glycol One of octyl phenyl ether, or a combination of more than one, wherein the molecular weight of the polyethylene glycol is 2000-10000.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 1, wherein the number of elbows of the pulsating heat pipe is greater than or equal to 6.
The pulsating heat pipe with liquid metal micro-nano droplets as the working fluid according to claim 1 or 5, wherein the angle between the operation direction of the pulsating heat pipe and the horizontal direction is 0°-90°.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 6, wherein the substrate of the pulsating heat pipe is copper, stainless steel or Teflon material.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 1, wherein the total volume filling rate of the pulsating heat pipe mixed working fluid ranges from 30% to 80%, wherein the mixed The mass fraction of the liquid metal in the working fluid is 10%-60%, the mass fraction of the surfactant solution is 40%-90%, and the mass concentration of the surfactant in the surfactant solution It is 0.01%-5%.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 1 or 8, characterized in that the working temperature of the pulsating heat pipe is 30°C-100°C.
The pulsating heat pipe with liquid metal micro-nano droplets as a working fluid according to claim 9, wherein the hydraulic diameter of the pulsating heat pipe is 2mm-4mm; the shape of the channel in the pulsating heat pipe is rectangular, square or round shape.