A self-adaptive temperature control device and method of non-azeotropic nanoemulsion micro-pulsating heat pipe

Abstract

The application discloses a non-azeotropic nanoemulsion micro pulsating heat pipe self-adaptive temperature control device, which utilizes a heat collecting device on the bottom surface of a reverse thermal convection chamber to concentrate heat and form a high temperature gradient hot spot. The low-boiling fluoride droplets in the non-azeotropic nanoemulsion move reversely by thermal convection, and the low-boiling point characteristics thereof are utilized to perform boiling heat exchange cooling and water convection auxiliary heat exchange cooling on the high temperature gradient hot spot. The boiling water and fluoride bubble mixture move to a condensing section under the driving of a pressure difference, the bubbles condense into nano droplets in the condensing section, mix with water to form non-azeotropic nanoemulsion again, and return to the reverse thermal convection chamber to form a flow closed loop. The movement of the non-azeotropic nanoemulsion in the pulsating heat pipe does not need external kinetic energy components, and the non-azeotropic nanoemulsion completes one-way circulation by absorbing heat in the reverse thermal convection chamber and releasing heat in the condensing section, thereby avoiding local overheating and boiling crisis caused by insufficient liquid supply of the high temperature gradient hot spot.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation technology for electronic devices, and in particular to an adaptive temperature control device for a non-azeotropic nanoemulsion micro-pulsating heat pipe. Background Technology

[0002] Data centers, as the infrastructure for storing, exchanging, processing, and managing large-scale data, are a crucial cornerstone supporting the development of "new infrastructure." With the increasing data throughput year by year, data centers are utilizing optical communication technology to achieve high-speed information transmission over short to medium distances. Vertical cavity surface emitting lasers (VCSELs) have become one of the main light sources for optical communication due to their advantages such as low threshold current, high-frequency modulation, and high fiber coupling efficiency. Integrating VCSELs into two-dimensional arrays can achieve high-speed, high-capacity optical data transmission. However, due to the small thermal conductivity and oxide aperture of the VCSEL array substrate, the overall series resistance of the device is relatively high, leading to localized hotspots (greater than 80°C) in the central emitting unit. Furthermore, thermal crosstalk occurs between adjacent units due to the lateral expansion and accumulation of heat, resulting in a large temperature gradient (~K / μm) between the central emitting unit and the edge areas. The heat accumulation caused by these high-temperature gradient hotspots causes premature saturation of the VCSEL array's output power and modulation bandwidth, severely limiting device performance and threatening its stability and lifespan. Therefore, to meet the future demands of data centers for high-speed, high-bandwidth, and high-quality data transmission, it is urgent to develop thermal management technologies for VCSEL arrays with high temperature gradient hotspots.

[0003] VCSEL arrays typically utilize bonded metal / non-metal thermal expansion materials or microchannel heat sinks to remove internal heat. However, the former suffers from problems such as a mismatch between thermal conductivity and coefficient of thermal expansion, complex manufacturing processes, and high costs. While the latter, with its flow boiling and thermistor-based microchannels, possesses the ability to sense hot spots and adaptively control temperature, it also faces issues such as flow instability, drying out of hot spots, and overcooling of non-hot spots. Furthermore, the kinetic energy components maintaining fluid flow increase system energy consumption. Micro-pulsating heat pipe technology utilizes the evaporation / boiling of the liquid working fluid, vapor condensation, 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, offering advantages such as compact structure, flexible arrangement, high heat transfer coefficient, and no need for additional energy input. Therefore, micro-pulsating heat pipes possess excellent temperature uniformity, thermal expansion, and low energy consumption characteristics, showing great potential in solving the problem of concentrated heat load in VCSEL arrays.

[0004] A micro-pulsating heat pipe typically consists of an evaporation section, an adiabatic section, and a condensation section. Usually, the pressure in the micro-pulsating heat pipe is first reduced to below 20 kPa, and a certain amount of pure working fluid is injected. Under the influence of surface tension, the working fluid forms several vapor and liquid plugs inside the pipe. When the evaporation section of the pulsating heat pipe is heated, the working fluid inside evaporates or boils, accompanied by the generation of bubbles. As heating continues, the pressure inside the evaporation section increases rapidly, pushing the working fluid from the evaporation section to the condensation section. The vapor undergoes condensation in the condensation section, releasing heat. The pressure in the condensation section decreases, and the working fluid flows back from the condensation section to the evaporation section under the influence of gravity.

[0005] Traditional micro-pulsating heat pipe technology utilizes the evaporation / boiling of liquid working fluid, vapor condensation, and the interaction between liquid plugs 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 heat and latent heat. It has advantages such as compact structure, flexible arrangement, 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, relying on gravity or pressure difference for liquid supply, struggle to deliver the working fluid to the hot spots in a timely and effective manner. This can easily lead to problems such as localized overheating and boiling crises caused by insufficient liquid supply, resulting in localized burnout or even device failure, threatening the device's safety and reliability. The boiling crisis occurs when 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 this invention is to provide an adaptive temperature control device for a non-azeotropic nanoemulsion micro-pulsating heat pipe, which solves the problem that traditional micro-pulsating heat pipes rely on gravity or pressure difference for liquid supply, and are prone to local overheating and boiling crises caused by insufficient liquid supply to hot spots with high temperature gradients.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

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

[0010] The reverse thermophoresis chamber is a cavity structure. A working fluid outlet channel connecting to the condensation section pipeline is opened on one side wall of the cavity structure, and a working fluid inlet channel connecting to the insulation section pipeline is opened on the other side wall of the cavity structure. The flow area of ​​the working fluid outlet channel is larger than the flow area of ​​the working fluid inlet channel. The condensation section pipeline is connected to the insulation section pipeline.

[0011] Multiple cylindrical heat-collecting needle ribs are provided on the bottom surface of the cavity of the cavity structure;

[0012] The cavity structure is also provided with a liquid inlet and a pressure relief port on its side wall.

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

[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 nanodroplets 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 needle ribs are evenly spaced on the bottom surface of the chamber.

[0018] Furthermore, the heat-collecting needle ribs are cylindrical structures, and heat is transferred between them and the bottom surface of the chamber.

[0019] Furthermore, the condensing section pipeline is a condensing section pipeline that connects the working fluid outlet channel and the insulation section pipeline respectively.

[0020] This embodiment provides an adaptive temperature control method for a non-azeotropic nanoemulsion micro-pulsating heat pipe, wherein a vacuum system is used to pump the internal pressure of 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, a non-azeotropic nanoemulsion is injected 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 needles installed on the bottom surface of the chamber, making the temperature of the heat-collecting needles significantly lower than that of the bottom surface of the chamber. The low-boiling-point fluoride nanodroplets in the reverse thermophoresis chamber move towards the heat-collecting needles under the action of the reverse thermophoretic force, and evaporate and boil on the heat-collecting needles, simultaneously forming bubbles. The convective heat transfer of water also assists in cooling the heat-collecting needles.

[0023] As the gas phase pressure in the reverse thermophoresis chamber increases, and the flow area of ​​the working fluid outlet channel is greater than that of the working fluid inlet channel, a pressure difference exists between the working fluid outlet channel and the working fluid inlet channel. Under the pressure, the water and the vapor bubbles formed by the heat collection needle fins move towards the working fluid outlet channel.

[0024] The water flows into the condensation section pipe, where the inner wall of the condensation section pipe is made of a hydrophilic material, and water forms a water film on the inner surface of the condensation section pipe. Since the temperature of the condensation section pipe is lower than the saturation temperature of the fluoride bubbles, the fluoride bubbles will condense into beads in the condensation section covered by the water film to form nanodroplets, and the nanodroplets and water will form a non-azeotropic nanoemulsion again.

[0025] Under the pressure of the liquid 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 fluid 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 beneficial technical effects of the present invention are as follows:

[0028] This invention utilizes a heat collection device on the bottom surface of the reverse thermophoresis chamber to concentrate heat and form a high-temperature gradient hotspot. Adaptive hotspot tracking is achieved through the reverse thermophoretic motion of low-boiling fluoride droplets in the non-azeotropic nanoemulsion. The low-boiling point of these droplets is then used for boiling heat exchange cooling and water convection-assisted heat exchange cooling of the high-temperature gradient hotspot. The boiled water and fluoride vapor mixture moves towards the condensation section under pressure differential. In the condensation section, the vapors condense into nanodroplets, mix with water, and reform the non-azeotropic nanoemulsion. This mixture then moves through the adiabatic section pipe towards the working fluid inlet channel and finally returns to the reverse thermophoresis chamber, forming a closed-loop flow. The movement of the non-azeotropic nanoemulsion in the pulsating heat pipe requires no external kinetic energy components. It completes a unidirectional circulation by absorbing heat in the reverse thermophoresis chamber and releasing heat in the condensation section. This avoids localized overheating and boiling crises caused by insufficient liquid supply to the high-temperature gradient hotspot. Attached Figure Description

[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 This is a top view schematic diagram of the adaptive temperature control device for the non-azeotropic nanoemulsion micro-pulsating heat pipe of the present invention.

[0032] Explanation of reference numerals in the attached diagram: 1. Insulation section pipeline; 2. Working fluid inlet channel; 3. Liquid inlet; 4. Pressure relief port; 5. Heat collection needle rib; 6. Chamber bottom surface; 7. Reverse thermophoresis chamber; 8. Condensation section pipeline; 9. Working fluid outlet channel; 10. Chamber top surface. Detailed Implementation

[0033] This embodiment discloses an adaptive temperature control device for a non-azeotropic nanoemulsion micro-pulsating heat pipe, comprising a closed-loop and sealed reverse thermophoresis chamber 7, a condensing section pipe 8, and an adiabatic section pipe 1. The reverse thermophoresis chamber 7 is a cavity structure. A working fluid outlet channel 9, connecting to the condensing section pipe, is formed on one side wall of the cavity structure. A working fluid inlet channel 2, connecting to the adiabatic section pipe 1, is formed 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 condensing section pipe is connected to the adiabatic section pipe 1. Multiple heat-collecting needle ribs 5 are installed on the bottom surface 6 of the cavity structure. An inlet port 3 and a pressure relief port 4 are also formed 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 liquid inlet 3 is opened or closed according to whether non-azeotropic nanoemulsion needs to be injected. In addition, the valve of the pressure relief port 4 is opened or closed according to whether vacuuming is needed for the reverse thermophoresis chamber 7, the condensation section pipeline, and the insulation section pipeline 1.

[0035] In this embodiment, a non-azeotropic nanoemulsion is injected into the reverse thermophoresis chamber 7 through the 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, vacuum pipes, vacuum valves, and an external filter assembly.

[0036] In this embodiment, as Figure 1 and Figure 2 As shown, the heat-collecting needle ribs 5 are evenly spaced on the bottom surface 6 of the chamber; specifically, the heat-collecting needle ribs 5 are cylindrical structures and transfer heat between themselves and the bottom surface 6 of the chamber. The heat-collecting needle ribs 5 can also be designed as pyramidal or prismatic shapes.

[0037] In this embodiment, the condensing section pipeline is a condensing section pipeline 8 that connects the working fluid outlet channel 9 and the insulating section pipeline 1 respectively; wherein when the working fluid passes through the condensing section pipeline 8, the large heat dissipation area of ​​the condensing section pipeline 8 facilitates the dissipation and condensation of the working fluid flowing through it.

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

[0039] The pressure inside the reverse thermophoresis chamber 7 is reduced to below 20 kPa using a vacuum system through the pressure relief port 4, and then the valve of the pressure relief port 4 is closed. A non-azeotropic nanoemulsion is then introduced into the reverse thermophoresis chamber 7 through the inlet 3. When the bottom surface 6 of the reverse thermophoresis chamber 7 is heated, the heat is gradually transferred to the cylindrical heat-collecting needle ribs 5 installed on the bottom surface 6, making the temperature of the heat-collecting needle ribs 5 significantly lower than that of the bottom surface 6. The low-boiling-point fluoride nanodroplets in the reverse thermophoresis chamber 7 move towards the heat-collecting needle ribs 5 under the action of the reverse thermophoresis force, and evaporate and boil on the heat-collecting needle ribs 5, forming bubbles. The convective heat transfer of water also assists in cooling the heat-collecting needle ribs 5. As the gas phase pressure in the reverse thermophoresis chamber 7 increases, and the flow area of ​​the working fluid outlet channel 9 is greater than that of the working fluid inlet channel 2, a pressure difference exists 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 needle ribs 5 move towards the working fluid outlet channel 9.

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

[0041] The principle of reverse thermophoresis involves the contributions of ionic and nonionic agents at the phase interface to the reverse thermophoresis mechanism of solid / liquid particles (including nanoemulsions) in colloidal solutions. Regarding the ionic mechanism, a dielectric constant gradient is formed within the electrical bilayer (EDL) of the colloidal particle interface when perturbed by a temperature gradient. This induces a slip flow from the hot end to the cold end on the particle surface, and the resulting interfacial entropy driving force pushes the colloidal particles toward the heat source. Regarding the nonionic contribution, the thermophoretic behavior of colloidal particles is affected by their surface excess enthalpy. When the excess enthalpy is positive, the particles exhibit "thermophilicity," and vice versa.

[0042] To quantitatively describe the reverse thermophoresis of colloidal particles, scholars both domestically and internationally have conducted extensive research 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 of particles) is obtained through optical measurements (such as thermal lenses, laser Rayleigh scattering, beam deflection, etc.) or microfluidic devices, and the Soret coefficient is then indirectly calculated. Some scholars have also established Soret coefficient models through theoretical analysis, such as the two-state theoretical model based on the hydration entropy effect and ion shielding effect proposed by Pu et al., and the composite model of coupled capacitance effect and thermoelectrophoresis mechanism constructed by Reichl et al. In evaluating thermophoretic force, its relationship with the Soret coefficient and temperature gradient, colloidal particle displacement, or methods based on steady-state mechanical equilibrium are typically used for theoretical prediction or experimental measurement. Overall, the reverse thermophoresis mechanism of colloidal particles involves ionic and nonionic interactions on the particle surface, and the thermophoretic migration law is also influenced by factors such as particle shape and size, ion concentration, interface modification, and average temperature.

[0043] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An adaptive temperature control method for a non-azeotropic nanoemulsion micro-pulsating heat pipe, characterized in that: Includes a closed-loop interconnected reverse thermophoresis chamber (7), a condensation section pipeline (8), and an insulation section pipeline (1); The reverse thermophoresis chamber (7) is a cavity structure. A working fluid outlet channel (9) connecting the condensing section pipeline is provided on one side wall of the cavity structure, and a working fluid inlet channel (2) connecting the insulating 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 condensing section pipeline (8) is connected to the insulating section pipeline (1). Multiple heat-collecting needle ribs (5) are provided on the bottom surface (6) of the cavity structure. The cavity structure is also provided with a liquid inlet (3) and a pressure relief port (4) on its side wall. In use, the pressure inside the reverse thermophoresis chamber (7) is reduced to below 20 kPa by a vacuum system through the pressure relief port (4), and then the valve of the pressure relief port (4) is closed. Then, a non-azeotropic nanoemulsion is injected into the reverse thermophoresis chamber (7) through the liquid inlet (3); When the bottom surface (6) of the reverse thermophoresis chamber (7) is heated, the heat is gradually transferred to the cylindrical heat-collecting needle ribs (5) installed on the bottom surface (6) of the chamber, making the temperature of the heat-collecting needle ribs (5) significantly lower than that of the bottom surface (6) of the chamber; the low-boiling-point fluoride nanodroplets in the reverse thermophoresis chamber (7) move towards the heat-collecting needle ribs (5) under the action of the reverse thermophoresis force, and evaporate and boil on the heat-collecting needle ribs (5), forming bubbles at the same time; the convective heat transfer of water also assists in cooling the heat-collecting needle ribs (5). As the gas phase pressure in the reverse thermophoresis chamber (7) increases, and the flow area of ​​the working medium outlet channel (9) is greater than that 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). Under the pressure, the water and the bubbles formed by the heat collection needle ribs (5) move towards the working medium outlet channel (9). And flow into the condensation section pipe (8), wherein the inner wall of the condensation section pipe (8) is made of a hydrophilic material, and water will form a water film on the inner surface of the condensation section pipe (8); since the temperature of the condensation section pipe (8) is lower than the saturation temperature of the fluoride bubbles, the fluoride bubbles will condense into beads in the condensation section pipe (8) covered with the water film to form nanodroplets, and the nanodroplets and water will form a non-azeotropic nanoemulsion again; Under the pressure of the liquid 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 fluid inlet channel (2).

2. The adaptive temperature control method for non-azeotropic nanoemulsion micropulsating heat pipes according to claim 1, characterized in that: Valves are provided at the liquid inlet (3) and the pressure relief port (4).

3. The adaptive temperature control method for non-azeotropic nanoemulsion micropulsating heat pipes according to claim 2, characterized in that: A non-azeotropic nanoemulsion is injected into the reverse thermophoresis chamber (7) through the inlet (3); the non-azeotropic nanoemulsion includes low-boiling-point nanodroplets and high-boiling-point droplets. The pressure relief port (4) is connected to a vacuum system.

4. The adaptive temperature control method for non-azeotropic nanoemulsion micropulsating heat pipes according to claim 3, characterized in that: The non-azeotropic nanoemulsion comprises low-boiling-point fluoride nanodroplets and high-boiling-point water.

5. The adaptive temperature control method for non-azeotropic nanoemulsion micropulsating heat pipes according to claim 1, characterized in that: The heat-collecting needle ribs (5) are evenly spaced on the bottom surface (6) of the chamber.

6. The adaptive temperature control method for non-azeotropic nanoemulsion micropulsating heat pipes according to claim 5, characterized in that: The heat-collecting needle rib (5) is a columnar structure and transfers heat between itself and the bottom surface (6) of the chamber.

7. The adaptive temperature control method for non-azeotropic nanoemulsion micropulsating heat pipes according to claim 1, characterized in that: The condensing section pipeline is a condensing section pipeline (8) that connects the working fluid outlet channel (9) and the insulation section pipeline (1).

8. The adaptive temperature control method for non-azeotropic nanoemulsion micropulsating heat pipes according to claim 1, characterized in that: The bottom surface (6) of the chamber serves as a heat dissipation unit for electronic devices.

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