Non-azeotropic nano-emulsion micro pulsating heat pipe self-adaptive temperature control device and method

Abstract

The invention discloses a non-azeotropic nano-emulsion micro pulsating heat pipe self-adaptive temperature control device which is characterized in that a heat collection device on the bottom surface of a reverse thermophoresis chamber is used for heat concentration to form a high-temperature gradient hot spot. By means of reverse thermophoresis movement of low-boiling-point fluoride liquid drops in the non-azeotropic nano-emulsion, boiling heat exchange cooling and convection auxiliary heat exchange cooling of water are carried out on high-temperature-gradient hot spots by means of the low-boiling-point characteristic of the low-boiling-point fluoride liquid drops. A mixture of boiled water and fluoride bubbles is driven by differential pressure to move towards the condensation section, the bubbles are condensed into nano liquid drops in the condensation section, the nano liquid drops are mixed with water to form a non-azeotropic nano emulsion again, and the non-azeotropic nano emulsion returns to the reverse thermophoresis chamber to form a flow closed loop. The movement of the non-azeotropic nano-emulsion in the pulsating heat pipe does not need an external kinetic energy part, and in the pulsating heat pipe, heat is absorbed by the reverse thermophoresis cavity and heat is released by the condensation section to complete one-way circulation, so that local overheating and boiling crisis caused by insufficient liquid supply of a high-temperature gradient hot spot are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation of electronic devices, in particular to a non-azeotropic nano-emulsion micro-pulsating heat pipe self-adaptive temperature control device. Background Art

[0002] Data centers, as infrastructure for storing, exchanging, processing, and managing large amounts of data, are a crucial cornerstone supporting the development of "new infrastructure." With data throughput increasing annually, data centers are leveraging optical communication technology to achieve high-speed information transmission over short and medium distances. Vertical cavity surface emitting lasers (VCSELs) have become one of the primary light sources for optical communications due to their low threshold current, high-frequency modulation, and high fiber coupling efficiency. Integrating VCSELs into two-dimensional arrays enables high-speed, high-capacity optical data transmission. Due to the low thermal conductivity and oxide aperture of the substrate in VCSEL arrays, the overall series resistance of the device is high, resulting in localized hotspots (greater than 80°C) forming in the central light-emitting unit. Furthermore, thermal crosstalk between adjacent units due to lateral heat expansion and accumulation creates significant temperature gradients (~K / μm) between the central light-emitting unit and the edges. Heat accumulation caused by these high-temperature hotspots can prematurely saturate the output power and modulation bandwidth of the VCSEL array, severely limiting device performance and threatening its stability and lifespan. Therefore, to meet the future demands of high-speed, high-bandwidth, and high-quality data transmission in data centers, there is an urgent need to develop thermal management technologies for these high-temperature hotspots in VCSEL arrays.

[0003] VCSEL arrays typically use bonded metal / non-metallic thermal expansion materials or microchannel heat sinks to dissipate internal heat. However, the former suffers from problems such as a mismatch between thermal conductivity and thermal expansion coefficient, complex manufacturing processes, and high costs. While the flow boiling and thermosensitive material-based microchannels in the latter have the ability to sense hot spots and adaptively control temperature, they also face problems such as flow instability, drying out in hot spots, and overcooling in non-hot spots. Furthermore, the kinetic energy components required to maintain fluid flow increase system energy consumption. Micro-pulsating heat pipe technology utilizes the evaporation / boiling of liquid working fluid, condensation of vapor, and the interaction between liquid and vapor plugs to form a closed loop of heat and mass transport. The working fluid transfers heat from the hot end to the cold end in the form of sensible and latent heat. It has the advantages of a compact structure, flexible layout, high heat transfer coefficient, and no need for additional energy input. Therefore, micro-pulsating heat pipes offer excellent temperature uniformity, thermal expansion, and low energy consumption, and have great potential in solving the problem of concentrated heat loads in VCSEL arrays.

[0004] A micro-pulsating heat pipe typically consists of an evaporator section, an adiabatic section, and a condenser section. The pressure is typically pumped down to below 20 kPa and a predetermined amount of pure working fluid is injected. Surface tension causes the working fluid to form several vapor and liquid plugs within the pipe. When the evaporator section of the pulsating heat pipe is heated, the working fluid evaporates or boils, generating bubbles. As heating continues, the pressure within the evaporator section rapidly increases, pushing the working fluid from the evaporator section to the condenser section. The vapor condenses in the condenser section, releasing heat, causing the pressure to decrease. Gravity forces the working fluid back from the condenser section to the evaporator section.

[0005] Traditional micro-pulsating heat pipe technology uses the evaporation / boiling of liquid working fluid, condensation of steam, and the interaction between liquid plug and vapor plug to form a closed loop of heat and mass transfer. The working fluid transfers heat from the hot end to the cold end in the form of sensible heat and latent heat. It has the advantages of compact structure, flexible layout, large heat transfer coefficient and no need for additional energy input.

[0006] However, when electronic devices have hot spots with high temperature gradients, traditional micro-pulsating heat pipes, which rely on gravity or pressure differentials to deliver fluid to the hot spots, struggle to deliver the fluid to them in a timely and effective manner. This can easily lead to localized overheating and boiling hazards caused by insufficient fluid supply, which can cause localized device burnout or even failure, threatening device safety and reliability. A boiling hazard is a phenomenon in which the heat flux density on the heating surface exceeds a certain critical value, causing a sharp drop in heat transfer efficiency and a rapid increase in the heating surface temperature. Summary of the Invention

[0007] The purpose of the present invention is to provide a non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device to solve the problem that traditional micro-pulsating heat pipes use gravity or pressure difference to supply liquid, which is very prone to local overheating and boiling crisis caused by insufficient liquid supply in high temperature gradient hot spots.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] The present invention provides a non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device, comprising a reverse thermophoresis chamber, a condensation section pipeline, and an insulation section pipeline connected in a closed loop;

[0010] The reverse thermophoresis chamber is a cavity structure, wherein a working fluid outlet channel connected to the condensing section pipeline is provided on one side wall of the cavity structure, and a working fluid inlet channel connected to the adiabatic section pipeline is provided on the other side wall of the cavity structure, wherein the flow area of ​​the working fluid outlet channel is larger than the flow area of ​​the working fluid inlet channel; the condensing section pipeline is connected to the adiabatic section pipeline;

[0011] A plurality of cylindrical heat collecting needle fins are provided on the bottom surface of the cavity structure;

[0012] A liquid inlet and a pressure relief port are also provided on the side wall of the cavity structure.

[0013] Furthermore, valves are respectively provided at the liquid inlet and the pressure relief port.

[0014] Furthermore, a non-azeotropic nanoemulsion is injected into the reverse thermophoresis chamber through the liquid inlet; the non-azeotropic nanoemulsion includes low-boiling point nano droplets and high-boiling point droplets;

[0015] The pressure relief port is connected to a vacuum system.

[0016] Furthermore, the non-azeotropic nanoemulsion comprises low-boiling-point fluoride nanodroplets and high-boiling-point water.

[0017] Furthermore, the heat collecting fins are evenly spaced apart on the bottom surface of the chamber.

[0018] Furthermore, the heat collecting needle fins are columnar structures and transfer heat to the bottom surface of the chamber.

[0019] Furthermore, the condensation section pipeline is a condensation section pipeline that is connected to the working medium outlet channel and the insulation section pipeline respectively.

[0020] This embodiment provides a method for adaptive temperature control of a non-azeotropic nanoemulsion micro-pulsating heat pipe, wherein a vacuum system is used to pump the pressure inside the reverse thermophoresis chamber to below 20 kPa through the pressure relief port, and then the valve of the pressure relief port is closed.

[0021] Then, the non-azeotropic nanoemulsion is filled into the reverse thermophoresis chamber through the liquid inlet;

[0022] When the bottom surface of the reverse thermophoresis chamber is heated, the heat is gradually transferred to the cylindrical heat-collecting fins mounted on the bottom surface, causing the temperature of the heat-collecting fins to be significantly lower than that of the bottom surface. Low-boiling-point fluoride nanodroplets in the reverse thermophoresis chamber move toward the heat-collecting fins under the action of reverse thermophoresis force, evaporate and boil on the heat-collecting fins, and form bubbles. Convective heat transfer of the water also assists in cooling the heat-collecting fins.

[0023] As the gas phase pressure in the reverse thermophoresis chamber increases, and at the same time, the flow area of ​​the working fluid outlet channel is larger than the flow area of ​​the working fluid inlet channel, a pressure difference exists between the working fluid outlet channel and the working fluid inlet channel. Driven by the pressure, the bubbles formed by the water and the heat collecting needle fins move toward the working fluid outlet channel.

[0024] The water flows into the condensation section pipeline, wherein the inner wall of the condensation section pipeline is made of a hydrophilic material, and the water forms a water film on the inner surface of the condensation section pipeline; since the temperature of the condensation section pipeline is lower than the saturation temperature of the fluoride bubbles, the fluoride bubbles condense in the condensation section covered with the water film to form nano-droplets, and the nano-droplets and water once again form a non-azeotropic nano-emulsion;

[0025] Under the action of the liquid pressure entering the condensation section pipeline, the non-azeotropic nanoemulsion flows to the adiabatic section pipeline and finally returns to the reverse thermophoresis chamber through the working medium inlet channel.

[0026] Furthermore, the bottom surface of the chamber serves as a heat dissipation unit for electronic devices.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] The present invention utilizes a heat collecting device on the bottom surface of the reverse thermophoresis chamber to concentrate heat and form a high temperature gradient hot spot. Relying on the reverse thermophoresis movement of low-boiling fluoride droplets in the non-azeotropic nanoemulsion, adaptive hot spot tracking is achieved, and then the high temperature gradient hot spot is cooled by boiling heat exchange and water convection-assisted heat exchange by utilizing its low boiling point characteristics. The boiling water and fluoride bubble mixture moves toward the condensation section under the drive of the pressure difference, and the bubbles condense into nano-droplets in the condensation section. After mixing with water, the non-azeotropic nanoemulsion is reformed and moves to the working fluid inlet channel through the adiabatic section pipeline, and finally returns to the reverse thermophoresis chamber to form a closed flow loop. The movement of the non-azeotropic nanoemulsion in the pulsating heat pipe does not require external kinetic energy components. In the pulsating heat pipe, the reverse thermophoresis chamber absorbs heat and the condensation section releases heat to complete the one-way cycle. This avoids the local overheating and boiling crisis caused by insufficient liquid supply to the high temperature gradient hot spot. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below with reference to the accompanying drawings.

[0030] Figure 1 This is a schematic diagram of the main structure of the non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device of the present invention;

[0031] Figure 2 It is a top view schematic diagram of the non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device of the present invention.

[0032] Explanation of the accompanying symbols: 1. Insulation section pipeline; 2. Working fluid inlet channel; 3. Liquid inlet; 4. Pressure relief port; 5. Heat collecting needle rib; 6. Chamber bottom; 7. Reverse thermophoresis chamber; 8. Condensation section pipeline; 9. Working fluid outlet channel; 10. Chamber top. DETAILED DESCRIPTION

[0033] This embodiment discloses a non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device, comprising a closed-loop and sealed reverse thermophoresis chamber 7, a condensation section pipeline 8, and an insulation section pipeline 1. The reverse thermophoresis chamber 7 is a cavity structure, and a working fluid outlet channel 9 connected to the condensation section pipeline is provided on one side wall of the cavity structure, and a working fluid inlet channel 2 connected to the insulation section pipeline 1 is provided on the other side wall of the cavity structure. The flow area of ​​the working fluid outlet channel 9 is larger than the flow area of ​​the working fluid inlet channel 2; the condensation section pipeline is connected to the insulation section pipeline 1. A plurality of heat collecting needle fins 5 are installed on the cavity bottom surface 6 of the cavity structure; and a liquid inlet 3 and a pressure relief port 4 are also provided on the side wall of the cavity structure.

[0034] In this embodiment, valves are installed at the liquid inlet 3 and the pressure relief port 4, respectively. The valves are used to open or close the liquid inlet 3 depending on whether the non-azeotropic nanoemulsion needs to be injected. In addition, the valve of the pressure relief port 4 is opened or closed depending on whether the reverse thermophoresis chamber 7, the condensation section pipeline, and the insulation section pipeline 1 need to be vacuumed.

[0035] In this embodiment, a non-azeotropic nanoemulsion is injected into the reverse thermophoresis chamber 7 through the liquid inlet 3; the non-azeotropic nanoemulsion includes low-boiling point nanodroplets and high-boiling point droplets; specifically, the non-azeotropic nanoemulsion includes low-boiling point fluoride nanodroplets and high-boiling point water. The pressure relief port 4 is connected to a vacuum system, which is a conventional vacuum system including a vacuum pump, a PLC program control system, a gas storage tank, a vacuum pipeline, a vacuum valve, an external filtration assembly, etc.

[0036] In this embodiment, Figure 1 and Figure 2 As shown, the heat collecting fins 5 are evenly spaced and installed on the bottom surface 6 of the chamber. Specifically, the heat collecting fins 5 are cylindrical structures and conduct heat transfer with the bottom surface 6 of the chamber. The heat collecting fins 5 can also be designed in a pyramidal or prism shape.

[0037] In this embodiment, the condensation section pipeline is a condensation section pipeline 8 that connects the working medium outlet channel 9 and the insulation section pipeline 1 respectively; when the hot working medium passes through the condensation section pipeline 8, the condensation section pipeline 8 has a large heat dissipation area, thereby facilitating heat dissipation and condensation of the working medium flowing therethrough.

[0038] This embodiment provides a non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control method, which specifically includes the following steps:

[0039] The vacuum system is used to pump the internal pressure of the reverse thermophoresis chamber 7 to a state lower than 20 kPa through the pressure relief port 4, and then the valve of the pressure relief port 4 is closed. The non-azeotropic nanoemulsion is then filled into the reverse thermophoretic chamber 7 through the liquid inlet 3. When the chamber bottom 6 of the reverse thermophoretic chamber 7 is heated, the heat is gradually transferred to the cylindrical heat collecting fins 5 mounted on the chamber bottom 6, causing the temperature of the heat collecting fins 5 to be significantly lower than that of the chamber bottom 6. The low-boiling-point fluoride nanodroplets in the reverse thermophoretic chamber 7 move toward the heat collecting fins 5 under the action of the reverse thermophoretic force, evaporate and boil on the heat collecting fins 5, and form bubbles. The convective heat transfer of the water also assists in cooling the heat collecting fins 5. As the gas phase pressure in the reverse thermophoretic chamber 7 increases, the flow area of ​​the working fluid outlet channel 9 becomes larger than the flow area of ​​the working fluid inlet channel 2, resulting in a pressure difference between the working fluid outlet channel 9 and the working fluid inlet channel 2. Under the pressure, the bubbles formed by the water and the heat collecting fins 5 move toward the working fluid outlet channel 9.

[0040] The liquid then flows into the condensing section pipe 8, the inner wall of which is made of a hydrophilic material. Water forms a water film on the inner surface of the condensing section pipe 8. Because the temperature of the condensing section pipe 8 is lower than the saturation temperature of the fluoride bubbles, the fluoride bubbles condense in the condensing section pipe 8, which is covered by the water film, to form nanodroplets. The nanodroplets and water then form a non-azeotropic nanoemulsion. Subsequently, under the pressure of the liquid entering the condensing section pipe 8, the non-azeotropic nanoemulsion flows toward the adiabatic section pipe 1 and ultimately returns to the reverse thermophoresis chamber 7 through the working medium inlet channel 2. In this embodiment, the chamber bottom 6 serves as a heat dissipation unit for electronic devices and can also be applied to other heat exchange components.

[0041] The reverse thermophoresis mechanism of solid / liquid particles in colloidal solutions (including nanoemulsions) involves both ionic and non-ionic contributions at the phase interface. Regarding the ionic mechanism, a temperature gradient perturbs the electrical double layer (EDL) at the colloidal particle interface, creating a dielectric constant gradient. This induces slip flow from the hot end to the cold end of the particle surface. The resulting interfacial entropy driving force propels the colloidal particles toward the heat source. Regarding the non-ionic contribution, the thermophoretic behavior of colloidal particles is influenced by their surface excess enthalpy. When the surface excess enthalpy is positive, the particles exhibit "thermophilic" behavior, while when it is negative, they exhibit "thermophilic" behavior.

[0042] To quantitatively describe the reverse thermophoresis of colloidal particles, researchers at home and abroad have conducted extensive research focusing on the Soret coefficient, thermophoretic diffusion coefficient, thermophoretic velocity, and thermophoretic force. The Soret coefficient (or thermophoretic diffusion coefficient) is a key parameter for determining the thermophoretic direction of colloidal particles and evaluating their thermophoretic velocity and force. The thermophoretic velocity of particles (or groups) can be obtained through optical measurements (such as thermal lensing, laser Rayleigh scattering, and beam deflection) or microfluidic devices, and the Soret coefficient can be indirectly calculated. Other researchers have established Soret coefficient models through theoretical analysis, such as the two-state theoretical model based on the hydration entropy effect and ion screening effect proposed by Pu et al. and the composite model combining the coupling capacitance effect and the thermophoretic mechanism constructed by Reichl et al. The evaluation of thermophoretic force is typically based on its relationship with the Soret coefficient, temperature gradient, and colloidal particle displacement, or on mechanical equilibrium methods under steady-state conditions for theoretical prediction or experimental measurement. Overall, the reverse thermophoresis mechanism of colloidal particles involves ionic and non-ionic interactions on the particle surface. The thermophoretic migration pattern is also influenced by factors such as particle shape and size, ion concentration, interface modification, and average temperature.

[0043] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device, characterized by: It comprises a reverse thermophoresis chamber (7), a condensation section pipeline (8), and an insulation section pipeline (1) that are connected in a closed loop; The reverse thermophoresis chamber (7) is a cavity structure, a working fluid outlet channel (9) communicating with the condensation section pipeline is provided on one side wall of the cavity structure, and a working fluid inlet channel (2) communicating with the adiabatic section pipeline (1) is provided on the other side wall of the cavity structure, the flow area of ​​the working fluid outlet channel (9) being larger than the flow area of ​​the working fluid inlet channel (2); the condensation section pipeline (8) is communicated with the adiabatic section pipeline (1); A plurality of heat-collecting needle fins (5) are provided on the cavity bottom surface (6) of the cavity structure; A liquid inlet (3) and a pressure relief port (4) are also provided on the side wall of the cavity structure.

2. The non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device according to claim 1, characterized in that: Valves are respectively provided at the liquid inlet (3) and the pressure relief port (4).

3. The non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device according to claim 2, characterized in that: A non-azeotropic nanoemulsion is injected into the reverse thermophoresis chamber (7) through the liquid inlet (3); the non-azeotropic nanoemulsion comprises low-boiling-point nano-droplets and high-boiling-point droplets; The pressure relief port (4) is connected to a vacuum system.

4. The non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device according to claim 3, characterized in that: The non-azeotropic nanoemulsion comprises low-boiling-point fluoride nanodroplets and high-boiling-point water.

5. The non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device according to claim 1, characterized in that: The heat collecting needle fins (5) are evenly spaced apart on the bottom surface (6) of the chamber.

6. The non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device according to claim 5, characterized in that: The heat collecting needle fins (5) are columnar structures and conduct heat transfer with the chamber bottom surface (6).

7. The non-azeotropic nanoemulsion micro-pulsating heat pipe adaptive temperature control device according to claim 1, characterized in that: The condensation section pipeline is a condensation section pipeline (8) that is connected to the working medium outlet channel (9) and the adiabatic section pipeline (1) respectively.

8. A method for adaptive temperature control of a non-azeotropic nanoemulsion micro-pulsating heat pipe, comprising the method according to any one of claims 1 to 7, wherein: wherein the internal pressure of the reverse thermophoresis chamber (7) is evacuated to a state below 20 kPa through the pressure relief port (4) by using a vacuum system, and then the valve of the pressure relief port (4) is closed; Then, the non-azeotropic nanoemulsion is filled into the reverse thermophoresis chamber (7) through the liquid inlet (3); When the chamber bottom surface (6) of the reverse thermophoresis chamber (7) is heated, the heat is gradually transferred to the cylindrical heat collecting needle fins (5) mounted on the chamber bottom surface (6), so that the temperature of the heat collecting needle fins (5) is significantly lower than that of the chamber bottom surface (6); the low-boiling-point fluoride nano-droplets in the reverse thermophoresis chamber (7) move toward the heat collecting needle fins (5) under the action of the reverse thermophoresis force, evaporate and boil on the heat collecting needle fins (5), and form bubbles at the same time; the convection heat transfer of the water simultaneously assists in cooling the heat collecting needle fins (5); As the gas phase pressure in the reverse thermophoresis chamber (7) increases, and at the same time the flow area of ​​the working medium outlet channel (9) is larger than the flow area of ​​the working medium inlet channel (2), a pressure difference exists between the working medium outlet channel (9) and the working medium inlet channel (2), and under the push of the pressure, the bubbles formed by the water and the heat collecting needle fins (5) move toward the working medium outlet channel (9); and flows into the condensation section pipeline (8), wherein the inner wall of the condensation section pipeline (8) is made of a hydrophilic material, and water forms a layer of water film on the inner surface of the condensation section pipeline (8); since the temperature of the condensation section pipeline (8) is lower than the saturation temperature of the fluoride bubbles, the fluoride bubbles condense in the condensation section pipeline (8) covered with the water film to form nano droplets, and the nano droplets and water form a non-azeotropic nanoemulsion again; Under the action of the liquid pressure entering the condensation section pipeline (8), the non-azeotropic nanoemulsion flows to the adiabatic section pipeline (1) and finally returns to the reverse thermophoresis chamber (7) through the working medium inlet channel (2).

9. The method for self-adapting temperature control of a non-azeotropic nanoemulsion micro-pulsating heat pipe according to claim 8, characterized in that: The chamber bottom surface (6) serves as a heat dissipation unit for electronic devices.

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