阅读说明：本技术 一种液态金属微纳液滴为工质的脉动热管 (Pulsating heat pipe with liquid metal micro-nano liquid drops as working media ) 是由 郝婷婷 马学虎 杨思艳 崔文宇 陈彦松 白涛 兰忠 于 2019-11-19 设计创作，主要内容包括：本发明提供一种液态金属微纳液滴为工质的脉动热管,包括脉动热管,所述脉动热管的工质是主要由液态金属和表面活性剂溶液组成的混合工质,所述液态金属被所述表面活性剂包覆,其中,所述脉动热管的蒸发段在加热条件下,产生大量微小气泡,所述液态金属被产生的气泡分散成多个具有微纳尺度的液态金属液滴,所述液态金属液滴分散在所述表面活性剂溶液中,所述液态金属液滴在所述脉动热管运行阶段自发产生；所述液态金属液滴为毫米级液滴、微米级液滴和纳米级液滴。本发明的脉动热管结合液态金属超高热导率和液态金属微纳液滴能产生局部微对流等特性,可显著提高脉动热管的传热性能和承载热负荷的能力。(The invention provides a pulsating heat pipe with liquid metal micro-nano droplets as a working medium, which comprises a pulsating heat pipe, wherein the working medium of the pulsating heat pipe is a mixed working medium mainly composed of liquid metal and a surfactant solution, the liquid metal is coated by the surfactant, wherein an evaporation section of the pulsating heat pipe generates a large number of micro-bubbles under the heating condition, the liquid metal is dispersed into a plurality of liquid metal droplets with micro-nano dimensions by the generated bubbles, the liquid metal droplets are dispersed in the surfactant solution, and the liquid metal droplets are spontaneously generated at the operation stage of the pulsating heat pipe; the liquid metal droplets are millimeter-sized droplets, micron-sized droplets and nanometer-sized droplets. The pulsating heat pipe provided by the invention combines the characteristics of ultrahigh heat conductivity of liquid metal, local micro-convection generated by liquid metal micro-nano liquid drops and the like, and can remarkably improve the heat transfer performance and the heat load bearing capacity of the pulsating heat pipe.)

1. The pulsating heat pipe with the liquid metal micro-nano droplets as the working medium is characterized by comprising the pulsating heat pipe, wherein the working medium of the pulsating heat pipe is a mixed working medium mainly composed of liquid metal and a surfactant solution, the surfactant solution is composed of a surfactant and water, and the liquid metal is coated by the surfactant, wherein an evaporation section of the pulsating heat pipe generates a large number of micro-bubbles under a heating condition, the liquid metal is dispersed into a plurality of liquid metal droplets with micro-nano dimensions by the generated bubbles, the liquid metal droplets are dispersed in the surfactant solution, and the liquid metal droplets are spontaneously generated at the operation stage of the pulsating heat pipe; the liquid metal droplets include millimeter-sized droplets, micron-sized droplets, and nanometer-sized droplets.

2. The pulsating heat pipe with liquid metal micro-nano droplets as working media according to claim 1, wherein the sizes of the liquid metal droplets have a certain distribution range, and millimeter-sized droplets, micron-sized droplets and nanometer-sized droplets exist simultaneously or micron-sized droplets and nanometer-sized droplets exist simultaneously.

3. The pulsating heat pipe with liquid metal micro-nano droplets as working media according to claim 1, wherein the liquid metal is one or more of gallium, indium and tin which are in a liquid state at a temperature of 20-50 ℃.

4. The pulsating heat pipe with liquid metal micro-nano droplets as working media according to claim 1, wherein the surfactant is at least one of an anionic surfactant, a cationic surfactant or a nonionic surfactant, or a combination of more than one of the anionic surfactant, the cationic surfactant and the nonionic surfactant; the anionic surfactant is an alkyl sulfate containing 8 to 16 carbon atoms, or an alkyl sulfonate containing 8 to 16 carbon atoms, or an alkyl benzene sulfonate containing 8 to 16 carbon atoms; the cationic surfactant is an alkyl dimethylamine oxide comprising 8 to 18 carbon atoms; the non-ionic surfactant is one of polyethylene glycol or polyethylene glycol octyl phenyl ether, or the combination of more than one of the polyethylene glycol and the polyethylene glycol octyl phenyl ether, wherein the molecular weight of the polyethylene glycol is 2000-10000.

5. The pulsating heat pipe with liquid metal micro-nano liquid drops as working media according to claim 1, wherein the number of bent pipes of the pulsating heat pipe is greater than or equal to 6.

6. The pulsating heat pipe with the liquid metal micro-nano liquid drops as working media according to claim 1 or 5, wherein an included angle between the operation direction of the pulsating heat pipe and the horizontal direction is 0-90 degrees.

7. The pulsating heat pipe with liquid metal micro-nano droplets as working media according to claim 6, wherein a base material of the pulsating heat pipe is red copper, stainless steel or a Teflon material.

8. The pulsating heat pipe with the liquid metal micro-nano liquid drops as the working medium according to claim 1, wherein the range of the total volume liquid filling rate of the mixed working medium of the pulsating heat pipe is 30% -80%, wherein the mass fraction of the liquid metal in the mixed working medium is 10% -60%, the mass fraction of the surfactant solution is 40% -90%, and the mass concentration of the surfactant in the surfactant solution is 0.01% -5%.

9. The pulsating heat pipe with the liquid metal micro-nano liquid drops as working media according to claim 1 or 8, wherein the working temperature range of the pulsating heat pipe is 30-100 ℃.

10. The pulsating heat pipe with the liquid metal micro-nano liquid drops as working media according to claim 9, wherein the hydraulic diameter of the pulsating heat pipe is 2mm-4 mm; the shape of the channel in the pulsating heat pipe is rectangular, square or circular.

Technical Field

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

Background

With the development of very large scale integrated circuits, the local heat flux density gradually increases, and if the heat cannot be dissipated effectively in time, the chip temperature is too high, which leads to performance degradation. Heat dissipation with high heat flux density at a small size is therefore a major bottleneck limiting the development of integrated circuits. The conventional method for improving the heat dissipation efficiency has almost reached the limit, and the lack of a new effective heat dissipation method has become one of the major bottlenecks restricting the development of new technologies. Therefore, it is very urgent and necessary to develop a high-efficiency heat dissipation technology under high heat flux density. The pulsating heat pipe is used as a special member of a heat pipe family, has a completely different working mechanism from a common heat pipe, has a plurality of unique advantages, is coupled with two heat transfer modes of phase change heat transfer and convection heat transfer, has higher effective heat conductivity, and becomes one of the most promising technical solutions of the heat dissipation problem under high heat flux density in the future.

The heat transfer mode of the pulsating heat pipe is mainly sensible heat transfer of liquid elastic oscillation motion of an evaporation section and a condensation section. The heat transfer performance of the pulsating heat pipe is obviously influenced by the working medium property and the flowing state of the pulsating heat pipe, and the heat transfer performance of the pulsating heat pipe is obviously improved by selecting the working medium with high heat conductivity. Liquid metal (gallium and its alloy) is a special material with high thermal conductivity of metal and liquid fluidity, the thermal conductivity of the liquid metal is dozens of times of that of water, and the national space and navigation administration (NASA) lists 'liquid metal cooling' as the leading technology in the future in 2014. Research shows that the Heat Transfer performance of the pulsating Heat pipe using liquid metal and water as working media is obviously improved (see: Hao et al, Journal of Heat Transfer,2019,141(7): 071802). The liquid metal also has a unique property, and under the action of bubbles and a surfactant solution, the liquid metal gallium can be dispersed into liquid metal droplets with the size of tens of nanometers to thousands of micrometers, so that the pulsating heat pipe taking the liquid metal micro-nano droplets as working media is formed. The surfactant is attached to the surface of the liquid metal droplet, so that the liquid metal droplet exists more stably. Therefore, the pulsating heat pipe of the liquid metal micro-nano liquid drop working medium provides a new idea and an efficient scheme for solving the problem of rapid heat dissipation of high heat flow density under a micro size, and simultaneously develops a new direction for the research of the efficient pulsating heat pipe.

Disclosure of Invention

According to the technical problems that with the development of a super-large-scale integrated circuit, the local heat flux density is gradually increased, the performance is reduced due to the fact that the chip temperature is too high due to the fact that heat cannot be effectively dissipated in time, and the heat dissipation of the high heat flux density under the micro size restricts the development of the integrated circuit, the pulsating heat pipe using liquid metal micro-nano liquid drops as working media is provided. The invention mainly improves the heat transfer performance of the pulsating heat pipe through the liquid metal micro-nano liquid drop working medium, and the working medium of the traditional pulsating heat pipe mainly comprises: water, ethanol, acetone and mixtures thereof, nanofluids and the like. The liquid metal is introduced into the working medium, the characteristic of ultrahigh heat conductivity of the liquid metal is utilized, meanwhile, the liquid metal is dispersed into micro-nano liquid drops which exist stably under the action of the surfactant, and the micro-nano liquid drops of the liquid metal are utilized as the pulsating heat pipe of the working medium, so that the heat transfer capacity and the capacity of bearing heat load of the pulsating heat pipe are improved remarkably.

The technical means adopted by the invention are as follows:

a pulsating heat pipe with liquid metal micro-nano droplets as a working medium comprises the pulsating heat pipe, wherein the working medium of the pulsating heat pipe is a mixed working medium mainly composed of liquid metal and a surfactant solution, the surfactant solution is composed of a surfactant and water, and the liquid metal is coated by the surfactant, wherein an evaporation section of the pulsating heat pipe generates a large number of micro-bubbles under a heating condition, the liquid metal is dispersed into a plurality of liquid metal droplets with micro-nano dimensions by the generated bubbles, the liquid metal droplets are dispersed in the surfactant solution, and the surface tension of the solution is reduced by the presence of the surfactant, so that the liquid metal droplets are not easy to merge to form the stably existing micro-nano droplets; the liquid metal liquid drops are spontaneously generated in the operation stage of the pulsating heat pipe, and the pulsating heat pipe can enable the liquid metal liquid drops to realize spontaneous movement under the driving of the pressure difference of phase change heat transfer; the liquid metal droplets include millimeter-sized droplets, micron-sized droplets and nanometer-sized droplets, and the size distribution of the liquid metal droplets is from millimeter to nanometer.

Further, the liquid metal droplet size has a certain distribution range, and the millimeter-sized droplet, the micron-sized droplet and the nanometer-sized droplet exist simultaneously or the micron-sized droplet and the nanometer-sized droplet exist simultaneously.

Further, the liquid metal is one of gallium, indium or tin which is in a liquid state at a temperature of 20-50 ℃, or a combination form of more than one. The liquid metal is a simple metal substance or a metal mixture which is in a liquid state at the temperature of 20-50 ℃, the simple metal substance is one of gallium, indium or tin, and the metal mixture is an alloy of at least two metals of gallium, indium or tin.

Further, the surfactant is at least one of an anionic surfactant, a cationic surfactant or a nonionic surfactant, or a combination of more than one of the surfactants; the anionic surfactant is an alkyl sulfate containing 8 to 16 carbon atoms, or an alkyl sulfonate containing 8 to 16 carbon atoms, or an alkyl benzene sulfonate containing 8 to 16 carbon atoms; the cationic surfactant is an alkyl dimethylamine oxide comprising 8 to 18 carbon atoms; the non-ionic surfactant is one of polyethylene glycol or polyethylene glycol octyl phenyl ether, or the combination of more than one of the polyethylene glycol and the polyethylene glycol octyl phenyl ether, wherein the molecular weight of the polyethylene glycol is 2000-10000.

Furthermore, 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 a dispersed phase of the mixed working medium, the surfactant solution is a continuous phase of the mixed working medium, the liquid metal micro-nano droplets are dispersed in the surfactant solution in the operation stage of the pulsating heat pipe, and the liquid metal is coated by the surfactant. The surface active agent is added, so that the surface tension of the continuous phase is obviously reduced, and the wetting property of the working medium in the pulsating heat pipe can be effectively enhanced. The added surfactant can be attached to the surface of the liquid metal micro-nano liquid drop, so that the liquid metal micro-nano liquid drop can exist stably for a long time.

Furthermore, the liquid metal droplets can form local oscillation motion in the process of flowing along with the fluid, so that local micro-convection is formed, and the heat transfer capacity of the working medium is further improved.

Further, the liquid metal droplet pulsating heat pipe combines the advantages of heat conduction of two fluids, liquid metal and water, wherein the liquid metal mainly transfers heat in a heat conduction mode, and the water mainly transfers heat in a convection mode. The pulsating heat pipe couples the heat transfer advantages of two fluids, and compared with a common working medium pulsating heat pipe, the heat transfer performance of the liquid metal micro-nano liquid drop pulsating heat pipe is remarkably improved.

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

Furthermore, the included angle between the operation direction of the pulsating heat pipe and the horizontal direction is 0-90 degrees.

Further, the heating mode of the pulsating heat pipe is related to the number of bent pipes of the pulsating heat pipe. When the number of the bent pipes of the pulsating heat pipe is 6-12, the included angle between the operation direction of the pulsating heat pipe and the horizontal direction is 10-90 degrees (the included angle between the operation direction of the pulsating heat pipe and the horizontal direction is 90 degrees, and the included angle is vertical to the bottom heating direction); when the number of the pulsating heat pipe bends is 13 or more, the included angle between the operating direction of the pulsating heat pipe and the horizontal direction is 0-90 degrees.

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

Furthermore, the base material 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 in a machining mode. And in the stable operation stage of the pulsating heat pipe, the motion rule and the size distribution of liquid metal droplets in the pulsating heat pipe are observed through high-speed camera shooting, and the size distribution result of the droplets is obtained through analysis and processing. Due to the pixel limitation of the collected pictures, the pictures collected by the high-speed camera only count the micron-sized liquid metal droplets with the diameter larger than 50 mu m. And after the experiment is finished, the working medium of the pulsating heat pipe is subjected to detailed test analysis, and the size distribution of the liquid metal nano liquid drops in the working medium is analyzed by a nano-particle size potentiometer.

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

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

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

Furthermore, the size of the liquid metal liquid drop is closely related to the working temperature and the input power of the pulsating heat pipe and the type and the concentration of the surfactant, the size distribution of the liquid metal liquid drop can be adjusted by adjusting the type, the concentration and the heating power of the surfactant, and the cooling and temperature control capacity of the pulsating heat pipe is improved.

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

1. the invention provides a pulsating heat pipe with liquid metal micro-nano liquid drops as working media, which improves the heat transfer performance of the pulsating heat pipe through the liquid metal micro-nano liquid drop working media, and the working media of the traditional pulsating heat pipe mainly comprise: water, ethanol, acetone and mixtures thereof, nanofluids and the like. The liquid metal is introduced into the working medium, the characteristic of ultrahigh heat conductivity of the liquid metal is utilized, meanwhile, the liquid metal is dispersed into micro-nano liquid drops which exist stably under the action of the surfactant, and the micro-nano liquid drops of the liquid metal are utilized as the pulsating heat pipe of the working medium, so that the heat transfer capacity and the capacity of bearing heat load of the pulsating heat pipe are improved remarkably.

2. According to the pulsating heat pipe with the liquid metal micro-nano liquid drops as the working medium, the liquid metal micro-nano liquid drops can be automatically generated in the pulsating heat pipe, the size distribution of the liquid metal liquid drops can be adjusted by adjusting the type, concentration and heating power of the surfactant, and the cooling and temperature control capacity of the pulsating heat pipe is improved.

3. The pulsating heat pipe with the liquid metal micro-nano liquid drops as the working medium provided by the invention has the advantages that the working medium of the pulsating heat pipe is a mixed working medium of the liquid metal and the surfactant solution, the thermal conductivity of the liquid metal is dozens of or even hundreds of times of that of a common working medium, and the thermal conductivity of the working medium of the pulsating heat pipe can be effectively improved.

4. The pulsating heat pipe with the liquid metal micro-nano droplets as the working medium provided by the invention has the advantages that the working medium of the pulsating heat pipe is a mixed working medium of the liquid metal and the surfactant solution, the liquid metal is dispersed into the micro-nano droplets, the liquid metal is a dispersed phase, the surfactant solution is a continuous phase, the surfactant is added, the surface tension of the continuous phase is obviously reduced, and the wettability of the working medium in the pulsating heat pipe can be effectively enhanced. The added surfactant can be attached to the surface of the liquid metal micro-nano liquid drop, so that the liquid metal micro-nano liquid drop can exist stably for a long time.

5. The liquid metal micro-nano liquid drop provided by the invention is a pulsating heat pipe of the working medium, the liquid metal micro-nano liquid drop can form local oscillation motion in the flowing process along with the fluid, local micro-convection is formed, and the heat transfer capacity of the working medium is further improved.

6. The pulsating heat pipe with the liquid metal micro-nano liquid drops as the working medium combines the advantages of heat conduction of two fluids, namely liquid metal and water, the liquid metal mainly transfers heat in a heat conduction mode, and the water mainly transfers heat in a convection mode. The pulsating heat pipe couples the heat transfer advantages of the two fluids, and compared with the common working medium pulsating heat pipe, the heat transfer performance of the liquid metal micro-nano liquid drop pulsating heat pipe is obviously improved.

In conclusion, the technical scheme of the invention can solve the problems that the local heat flux density is gradually increased along with the development of the ultra-large scale integrated circuit, the performance is reduced due to overhigh chip temperature caused by the failure of timely and effective heat dissipation, and the development of the integrated circuit is restricted by the heat dissipation of high heat flux density under a micro size in the prior art.

Based on the reason, the invention can be widely popularized in the fields of microelectronic chip heat dissipation and cooling, industrial waste heat recovery, process heat exchange and the like under high heat flux by using the pulsating heat pipe for heat transfer.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

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

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

Fig. 3 is a size distribution diagram of liquid metal micro-nano liquid drops in steady-state operation of the pulsating heat pipe.

Fig. 4 is a size distribution diagram of liquid metal micro-nano liquid drops in steady-state operation of the pulsating heat pipe.

Fig. 5 is a size distribution diagram of liquid metal micro-nano liquid drops in steady-state operation of the pulsating heat pipe.

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

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

FIG. 8 is a droplet size distribution diagram of a liquid metal micro-nano droplet pulsating heat pipe under different surfactant concentrations.

FIG. 9 is a size distribution diagram of liquid metal nano-droplets in the working medium of the pulsating heat pipe according to the present invention.

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

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

In the figure: 1. a liquid phase; 2. liquid metal micro-nano liquid drops; 3. air bubbles.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the absence of any contrary indication, these directional terms are not intended to indicate and imply that the device or element so referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be considered as limiting the scope of the present invention: the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

As shown in fig. 1-2, the present invention provides a pulsating heat pipe using liquid metal micro-nano droplets as a working medium, including a pulsating heat pipe, where the working medium of the pulsating heat pipe includes but is not limited to a mixed working medium of a surfactant solution and a liquid metal or an alloy of the liquid metal, the surfactant solution is composed of a surfactant and water, and the liquid metal is coated by the surfactant, where an evaporation section of the pulsating heat pipe generates a large number of micro-bubbles 3 under a heating condition, the liquid metal is dispersed into a plurality of liquid metal droplets with micro-nano scale by the generated bubbles 3, the liquid metal droplets are dispersed in the surfactant solution, and the presence of the surfactant reduces the surface tension of the solution, so that the liquid metal droplets are not easily merged to form stably existing micro-nano droplets; the liquid metal liquid drops are spontaneously generated in the operation stage of the pulsating heat pipe, and the pulsating heat pipe can enable the liquid metal liquid drops to realize spontaneous movement under the driving of the pressure difference of phase change heat transfer; the liquid metal droplets include millimeter-sized droplets, micron-sized droplets and nanometer-sized droplets, and the size distribution of the liquid metal droplets is from millimeter to nanometer.

The sizes of the liquid metal droplets have a certain distribution range, and the millimeter-sized droplets, the micron-sized droplets and the nanometer-sized droplets exist simultaneously or the micron-sized droplets and the nanometer-sized droplets exist simultaneously.

The liquid metal is one of gallium, indium or tin which is in a liquid state at the temperature of 20-50 ℃, or a combination form of more than one. That is, the liquid metal is a simple metal or a metal mixture which is liquid at a temperature of 20 ℃ to 50 ℃, the simple metal includes but is not limited to gallium, indium and tin, and the metal mixture includes but is not limited to an alloy of at least two metals of gallium, indium and tin.

The surfactant is at least one of an anionic surfactant, a cationic surfactant or a nonionic surfactant, or a combination of more than one of the surfactants; the anionic surfactant includes, but is not limited to, an alkyl sulfate containing 8 to 16 carbon atoms, or an alkyl sulfonate containing 8 to 16 carbon atoms, or an alkyl benzene sulfonate containing 8 to 16 carbon atoms; the cationic surfactant includes, but is not limited to, alkyl dimethylamine oxides containing 8 to 18 carbon atoms; the nonionic surfactant includes, but is not limited to, polyethylene glycol octylphenyl ether, and mixtures thereof, wherein the molecular weight of the polyethylene 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 a dispersed phase of the mixed working medium, the surfactant solution is a continuous phase of the mixed working medium, the liquid metal micro-nano droplets 2 are dispersed in the surfactant solution in the operation stage of the pulsating heat pipe, and the liquid metal is coated by the surfactant. The surface active agent is added, so that the surface tension of the continuous phase is obviously reduced, and the wetting property of the working medium in the pulsating heat pipe can be effectively enhanced. The added surfactant can be attached to the surface of the liquid metal micro-nano liquid drop 2, so that the liquid metal micro-nano liquid drop 2 can be ensured to exist stably for a long time.

The liquid metal drops can form local oscillation motion in the flowing process along with the fluid, so that local micro-convection is formed, and the heat transfer capacity of the working medium is further improved.

The liquid metal droplet pulsating heat pipe combines the advantages of heat conduction of two fluids, namely liquid metal and water, wherein the liquid metal mainly transfers heat in a heat conduction mode, and the water mainly transfers heat in a convection mode. The pulsating heat pipe couples the heat transfer advantages of two fluids, and compared with a common working medium pulsating heat pipe, the heat transfer performance of the liquid metal micro-nano liquid drop pulsating heat pipe is remarkably improved.

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

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

The heating mode of the pulsating heat pipe is related to the number of bent pipes of the pulsating heat pipe. When the number of the bent pipes of the pulsating heat pipe is 6-12, the included angle between the operation direction of the pulsating heat pipe and the horizontal direction is 10-90 degrees (the included angle between the operation direction of the pulsating heat pipe and the horizontal direction is 90 degrees, and the included angle is vertical to the bottom heating direction); when the number of the pulsating heat pipe bends is 13 or more, the included angle between the operating direction of the pulsating heat pipe and the horizontal direction is 0-90 degrees.

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

The base material 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 in a machining mode. And in the stable operation stage of the pulsating heat pipe, observing the motion rule and the size distribution of liquid metal droplets in the pulsating heat pipe through a high-speed camera, and analyzing and processing to obtain the size distribution result of the droplets, wherein the high-speed camera selects Phototron Fastcam Apx-Rs in Japan. Due to the pixel limitation of the collected pictures, the pictures collected by the high-speed camera only count the micron-sized liquid metal droplets with the diameter larger than 50 mu m. After the experiment is finished, the working medium of the pulsating heat pipe is tested and analyzed in detail, and the size distribution of liquid metal Nano liquid drops in the working medium is analyzed through a Nano-particle size potentiometer, wherein the Nano-particle size potentiometer selects Malvern Zetasizer Nano ZS90 in the United states.

The total volume liquid filling rate range of the pulsating heat pipe mixed working medium is 30% -80%, wherein the mass fraction of the liquid metal in the mixed working medium is 10% -60%, the mass fraction of the surfactant solution 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 30-100 ℃.

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

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