Liquid cooling working medium, preparation method thereof and electronic equipment

Abstract

The embodiment of the invention provides a liquid cooling working medium, the liquid cooling working medium is used for carrying out immersed liquid cooling heat dissipation on electronic equipment, and the liquid cooling working medium comprises the following components in parts by mass: 94-100 parts of fluorinated liquid, 0-5 parts of heat-conducting powder and 0-1 part of a stabilizer, the heat-conducting powder is heat-conducting powder treated by a surface treating agent, and the surface treating agent is a fluorine-containing silane coupling agent; the heat-conducting powder with a certain proportion content is added into the liquid cooling working medium with the base liquid being the fluorinated liquid, so that the heat-conducting property of the prepared liquid cooling working medium is superior to that of a common product.

Description

Technical Field

[0001] The present application relates to the field of electronic equipment, and in particular to an immersion liquid cooling medium and a preparation method thereof. Background Art

[0002] With the development of science and technology, Internet providers, enterprise platforms, scientific research institutions, etc. need to store a large amount of data and also have a large demand for computing power. The operating platform that carries the storage, calculation and transmission of data is called a data center. Nowadays, with the increasing demand for digital information, electronic equipment in data centers has gradually developed from low density to high density. High-density electronic equipment will generate a lot of heat when running. Therefore, how to dissipate heat for electronic equipment in data centers is a hot issue currently studied in the industry. Traditional heat dissipation methods include air cooling. However, the heat dissipation efficiency of air cooling has also become a bottleneck as the demand for heat dissipation of electronic equipment increases. In addition, air cooling requires fans and heat dissipation channels to be set up inside electronic equipment, and the space requirements inside electronic equipment are relatively high, which is contrary to the development trend of miniaturization of electronic equipment. In recent years, liquid cooling has gradually replaced traditional air cooling due to its advantages of higher heat dissipation efficiency, saving space inside electronic equipment, and low energy consumption. Immersed liquid cooling technology is a cooling technology that uses liquid as a heat transfer working medium (hereinafter referred to as working medium), completely or partially immerses the heat-generating electronic devices in electronic equipment in liquid, and the heat-generating electronic devices are in direct contact with the working medium and perform heat exchange. The material type and composition of the working fluid can directly affect the heat dissipation effect of the working fluid. Therefore, how to prepare a working fluid with high thermal conductivity to improve the heat dissipation effect of electronic equipment is a problem that the industry is currently concerned about. Summary of the invention

[0003] The embodiments of the present application provide a liquid cooling medium and a preparation method thereof, and an electronic device, which solve the problem of poor heat transfer performance of the liquid cooling medium.

[0004] In a first aspect, an embodiment of the present application provides a liquid cooling medium, which is used for immersion liquid cooling of electronic equipment. The liquid cooling medium includes the following components in parts by weight: 94 to 100 parts of fluorinated liquid, 0 to 5 parts of thermally conductive powder, and 0 to 1 part of a stabilizer; the thermally conductive powder is a thermally conductive powder treated with a surface treatment agent, and the surface treatment agent is a fluorine-containing silane coupling agent.

[0005] By adding a certain proportion of thermally conductive powder to a liquid cooling medium whose base liquid is a fluorinated liquid, the thermal conductivity of the prepared liquid cooling medium is better than that of general products. At the same time, due to the basic characteristics of the fluorinated liquid, such as low dielectric constant, stable chemical inertness, and system compatibility, the liquid cooling medium can be well and stably used in immersion liquid cooling of electronic equipment such as servers; Fluorinated silane coupling agent is a type of liquid substance that builds a "molecular bridge" between the interface of inorganic thermally conductive powder and organic fluorinated liquid. One end contains a siloxane group that is friendly to inorganic powder, and the siloxane group undergoes hydrolysis to form a chemical bond with the surface of the powder; the other end is a segment group with a carbon-fluorine skeleton, which forms an intermolecular force with the fluorinated liquid. By treating the thermally conductive powder with a surface treatment agent, the liquid powder of the working fluid can be kept stable for a long time without deposition and agglomeration, further improving the heat transfer and thermal conductivity of the liquid cooling medium.

[0006] In some implementations, the particle size of the thermally conductive powder is: 1 to 500 nm. The embodiment of the present application limits the particle size of the thermally conductive powder to a certain size range. Adding thermally conductive powder within this size range can make the thermal conductivity of the liquid cooling medium better. If the selected particle size is too small, the specific surface area may be too large, the viscosity of the system increases significantly, and it is not possible to form a better thermal conduction path when dispersed in the system. There will be no obvious improvement in the thermal conductivity of the liquid cooling medium. If the selected particle size is too large, the thermally conductive powder will not be easy to disperse and will easily produce agglomeration and deposition, and the thermal conductivity of the liquid cooling medium will be affected. Therefore, selecting a thermally conductive powder in the above-mentioned particle size range can make the thermal conductivity of the liquid cooling medium better.

[0007] In some implementations, the particle size of the thermally conductive powder is 1 nm to 100 nm. Further selecting the particle size of the thermally conductive powder to be the above size can further improve the thermal conductivity of the liquid cooling medium.

[0008] In some implementations, the fluorinated liquid is one or more of: hexafluoropropylene dimer, hexafluoropropylene trimer, perfluoroalkane, perfluoroketone, hydrofluoroether, perfluoropolyether, and hydrofluoroolefin.

[0009] In some implementations, the thermally conductive powder is one or more of nano-silicon dioxide, nano-aluminum oxide, nano-zinc oxide, nano-boron nitride, nano-silicon carbide, nano-aluminum hydroxide, carbon nanotubes, graphene, and diamond.

[0010] In some implementations, the surface treatment agent is one or more of trifluoropropane trimethoxysilane, heptadecafluorodecyl trimethoxysilane, and tridecafluorooctyl triethoxysilane.

[0011] In a second aspect, an embodiment of the present application provides a method for preparing a liquid cooling medium, wherein the liquid cooling medium is used for immersion cooling of electronic equipment, and the preparation method comprises the following steps:

[0012] S1. Spray and mix the liquid surface treatment agent and the thermal conductive powder in a mass ratio of 1:1, wash with anhydrous ethanol after mixing, and filter to remove excess surface treatment agent;

[0013] S2, drying the thermally conductive powder at 40-80° C. for 1-1.5 hours to obtain a surface-treated thermally conductive powder;

[0014] S3, adding the stabilizer to the fluorinated liquid, and dispersing it with a disperser at room temperature; the speed of the disperser is 5000-10000 rpm, and the dispersing time is 20-40 minutes to obtain a fluorinated liquid mixture;

[0015] S4. Add the surface treated thermally conductive powder into the fluorinated liquid mixture, and disperse it with a disperser at room temperature. The speed of the disperser is 10000-20000 rpm, and the dispersion time is 0.5-1.5 hours to obtain the liquid cooling medium.

[0016] The thermal conductivity of the liquid cooling medium prepared by the above method by adding a certain proportion of thermal conductive powder to the liquid cooling medium whose base liquid is fluorinated liquid is better than that of general products. At the same time, due to the basic characteristics of the fluorinated liquid such as low dielectric constant, stable chemical inertness, and system compatibility, the liquid cooling medium can be well and stably used in the immersion liquid cooling of electronic equipment such as servers; by treating the thermal conductive powder with a surface treatment agent, the liquid powder of the working medium can maintain long-term stability without deposition and agglomeration, thereby further improving the heat transfer and thermal conductivity of the liquid cooling medium.

[0017] In some implementations of the second aspect, the particle size of the thermally conductive powder is 1 to 500 nm.

[0018] In some implementations, the fluorinated liquid is one or more of: hexafluoropropylene dimer, hexafluoropropylene trimer, perfluoroalkane, perfluoroketone, hydrofluoroether, perfluoropolyether, and hydrofluoroolefin.

[0019] In some implementations of the second aspect, the thermally conductive powder is one or more of nano-silicon dioxide, nano-aluminum oxide, nano-zinc oxide, nano-boron nitride, nano-silicon carbide, nano-aluminum hydroxide, carbon nanotubes, graphene, and diamond.

[0020] In some implementations of the second aspect, the surface treatment agent is one or more of trifluoropropane trimethoxysilane, heptadecafluorodecyl trimethoxysilane, and tridecafluorooctyl triethoxysilane.

[0021] In some implementations of the second aspect, the stabilizer is one or more of Tween 20, Tween 40, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and OP-10 dodecylphenol polyoxyethylene ether.

[0022] In a third aspect, an embodiment of the present application provides an electronic device, comprising a shell, a circuit board being arranged in the shell, electronic devices being arranged on the circuit board, a liquid-cooling medium as claimed in any one of claims 1 to 6 or a liquid-cooling medium obtained by a preparation method as claimed in any one of claims 7 to 12 being arranged in the shell, and the electronic devices being immersed or partially immersed in the liquid-cooling medium.

[0023] In combination with the first aspect and the second aspect, the liquid cooling medium in the electronic device provided in the third aspect of the embodiment of the present application has the advantages of the first aspect and the second aspect, so that the electronic device has a good heat dissipation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 It is a schematic diagram of the three-dimensional structure of a data center provided in an embodiment of the present application;

[0026] Figure 2 is a schematic diagram of the structure of an electronic device of a data center provided in an embodiment of the present application;

[0027] Figure 3 It is a schematic diagram of the internal structure of an electronic device provided in an embodiment of the present application.

[0028] Main component symbols

[0029] Computer room 200

[0030] Computing device 300

[0031] Cabinet 201

[0032] Electronic equipment 202

[0033] Cabinet 304

[0034] Cabinet door 303

[0035] Housing 410

[0036] Circuit Board 450

[0037] Electronic Devices 420

[0038] Heat sink 430

[0039] Coolant 440

[0040] Cavity 411

[0041] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present application will be clearly and completely described below in conjunction with the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present invention.

[0043] The terms "first", "second", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] The following first briefly introduces the basic concepts involved in the embodiments of the present application.

[0045] Fluorinated liquid: Fluorinated liquid is a chemical solvent that was originally used as a circuit board cleaner. Its insulating and non-flammable inert properties make it used in data center liquid cooling and is the most widely used immersion coolant.

[0046] Surface treating agent: Surface treating agent refers to the agent used to treat the surface of a material to achieve a specific purpose.

[0047] Surfactant: Surfactant, also known as interfacial agent, is a compound that can reduce the surface tension or interfacial tension between two liquids, between liquid and gas, and between liquid and solid.

[0048] Fluorinated silane coupling agent: It is prepared by the addition of silyl chloroform and unsaturated olefins with reactive groups (carbon-fluorine (CF) as the skeleton) under catalysis and alcoholysis. It is a compound that has both hydrolyzable siloxane groups (reacting with inorganic substances) and fluorine-containing organic functional groups (a type of group with carbon-fluorine as the skeleton).

[0049] Siloxane group: a class of compounds with a silicon-oxygen-silicon (Si-O-Si) bond skeleton. This type of H (OSiH2) n OH parent (chain siloxane), or cyclic (OSiH2) n Derivatives of siloxanes (cyclosiloxanes). Functional groups R3Si-O- containing a single silicon atom are called alkoxysilyl groups. Siloxanes have a set of abbreviations based on the different groups that make up the molecule: M-group: (CH3)3SiO 0.5 , D-group: (CH3)2SiO, T-group: (CH3)SiO 1.5 .

[0050] Fluorinated group: a type of group with carbon-fluorine (CF) as the skeleton.

[0051] Single-phase liquid cooling: Single-phase liquid cooling means that the coolant does not undergo phase change during the circulation process and remains in liquid state. After the low-temperature coolant takes away the heat, the temperature rises, and the elevated coolant flows to other areas and then recools to complete the cycle; single-phase liquid cooling requires a high boiling point for the coolant, and the control of coolant evaporation loss is relatively simple. It has high compatibility with the components of electronic equipment, and the cooling medium is less contaminated, but its cooling efficiency is lower than that of two-phase liquid cooling.

[0052] Two-phase liquid cooling: Two-phase liquid cooling refers to the phase change of the coolant during the circulation and heat dissipation process. After the coolant takes away the heat from the electronic components, it undergoes a phase change and vaporizes. The gaseous coolant is condensed by other equipment and becomes liquid again. Since the coolant undergoes a phase change in two-phase liquid cooling, the heat transfer efficiency is very high. The disadvantage is that during this phase change process, the coolant will escape during the process of evaporating into a gaseous state, so there are certain requirements for the sealing of the container.

[0053] Dielectric constant: Dielectric constant is the main parameter that reflects the dielectric properties or polarization properties of piezoelectric smart material dielectric under the action of electrostatic field. It is usually expressed by ε. Piezoelectric elements for different purposes have different requirements for the dielectric constant of piezoelectric smart materials.

[0054] Thermal conductivity: Thermal conductivity refers to the amount of heat transferred through an area of ​​1 square meter under stable heat transfer conditions when the temperature difference between the two surfaces of a 1m thick material is 1 degree (K, ℃) within a certain period of time. The unit is watt / meter·degree (W / (m·K), K here can be replaced by ℃).

[0055] In order to facilitate understanding of the embodiments of the present application, the application scenarios of the embodiments of the present application are first introduced. Figure 1 As shown, the data center 1000 may include a computing device 300 disposed inside a computer room 200, and the computing device 300 may include a cabinet 201 and an electronic device 202 disposed inside the cabinet 201. Figure 1 The computer room shown is provided with 3 computing devices, but the actual application scenario may include more or fewer computing devices, for example, 50-100 computing devices. No specific limitation is made here. The computer room 200 may also include a cooling dispensing unit (CDU) (not shown in the figure), which can provide cooling liquid for the computing device 300 and circulate the cooling liquid so that the cooling liquid that absorbs the internal heat of the computing device 300 returns from the computing device 300 to the cooling liquid dispensing unit for cooling and redistribution to the computing device 300.

[0056] like Figure 2 As shown, a computing device 300 includes a cabinet 301, the cabinet 301 includes a cabinet body 304 and a cabinet door 303, and an electronic device 302 arranged in the cabinet 301, the electronic device 302 may be a server, Figure 2 The computing device 300 shown includes at least one server, and the server can be installed in the cabinet 301 through a sliding track (not shown in the figure). The height of each server is different, and can be 1U, 2U, 5U and other heights. In the embodiment of the present application, the electronic device 302 is taken as an example as a server, and the computing device 300 can be a whole cabinet server or a rack server. Among them, a heat dissipation device can also be provided on the cabinet door 303. For example, the cabinet door 303 can be set as a liquid cooling door. Exemplarily, a liquid cooling pipe can be provided inside the cabinet door 303, and a coolant is provided in the liquid cooling pipe; heat dissipation holes can also be opened on the cabinet body 304 or the cabinet door 303 of the cabinet 301 to enhance the heat dissipation capacity of the computing device 300.

[0057] like Figure 3 As shown, Figure 3 The schematic diagram of the internal structure of the server is shown. Figure 3 The liquid cooling medium is coolant 440. Figure 3The server includes a shell 410, a circuit board 450 is arranged in the shell 410, a heat-generating electronic device 420 is arranged on the circuit board 450, a heat sink 430 is arranged above the electronic device 420, and the heat sink 430 is used to dissipate heat from the electronic device 420 and take away the heat generated when the electronic device 420 is working; a coolant 440 is also arranged inside the shell 410, the circuit board 450, the electronic device 420, and the heat sink 430 are all immersed in the coolant 440, and the coolant 440 is used to dissipate heat from the electronic device 420 and take away the heat generated when the electronic device 420 is working; the shell 410 has a cavity 411 inside, and the cavity 411 can protect the electronic device 420, the circuit board 450 and the heat sink 430, prevent the electronic device 420 and the heat sink 430 from being contaminated by external impurities, and ensure the heat dissipation effect of the heat sink 430. At the same time, the cavity 411 also has a certain sealing effect, which can prevent the coolant 440 from leaking to the outside of the shell 410. The electronic device may be a central processing unit (CPU), a graphics processing unit (GPU), a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), and the like.

[0058] A liquid inlet and a liquid outlet (not shown in the figure) can also be set on the outer wall of the shell. The liquid inlet is connected to one end of the liquid inlet pipe, and the other end of the liquid inlet pipe is connected to the cold liquid distribution device CDU. The liquid outlet is connected to one end of the liquid outlet pipe, and the other end of the liquid outlet pipe is connected to the cold liquid distribution device CDU. The cooling liquid 440 enters the cavity 411 inside the shell 410 through the liquid inlet. After absorbing the heat of the electronic device 420, the cooling liquid 440 can return to the cold liquid distribution device CDU through the liquid outlet. After cooling the cooling liquid 440, the cold liquid distribution device CDU can circulate back to the cavity 411 inside the shell 410 through the liquid inlet.

[0059] Figure 3 The liquid cooling method shown in the figure can be single-phase liquid cooling, that is, the cooling medium does not undergo phase change during the circulation process and always maintains a liquid state; it can also be two-phase liquid cooling. At this time, the cooling medium can use the surface of the heat sink 430 for boiling heat exchange, and the gas generated by the liquid-to-gas phase change can take away the heat generated by the electronic device 420; it should be noted that in the two-phase liquid cooling scenario, the shell 410 is located above the liquid surface, and an air outlet can also be provided to clear the gas generated by the liquid-to-gas phase change to the outside of the chassis.

[0060] In some implementations, in order to further enhance the heat dissipation effect of the server, a spray pipe (not shown in the figure) can also be set above the liquid level in the shell 410, and the spray pipe is used to spray cooling medium to the electronic device 420 to dissipate heat therefrom.

[0061] In some implementations, in order to save the amount of cooling medium, the cooling medium may also partially immerse the electronic device 420 and the circuit board 450 , and the heat dissipation effect on the electronic device 420 may also be achieved.

[0062] Figure 3 The cooling medium shown can be divided into three types according to its properties: water, oil, and fluorinated liquid. Since water can easily introduce impurity ions that reduce its electrical insulation, thus causing equipment short circuit, the application of water as a liquid cooling medium is not common. Although oils have high electrical insulation properties, there is a risk of flash point flammability and they are difficult to clean. Therefore, their use as liquid cooling medium is not popular. Fluorinated liquid working fluids have been widely recognized and widely used due to their advantages and characteristics such as high insulation, low viscosity, low or even non-toxicity, good compatibility and stability, non-flammability, low global shorting potential (GWP), and zero ozone depletion potential (ODP). Currently, single-phase and two-phase fluorinated liquids from the international 3M company are widely used.

[0063] In order to meet the data center's demand for efficient and timely heat dissipation, fluorinated liquid is used as an immersion liquid cooling medium and requires it to have certain insulation stability, high thermal conductivity, dielectric properties, environmental friendliness and other characteristics. In the related technology, in order to make the liquid cooling medium have comprehensive characteristics, the general thermal conductivity is low, and the thermal conductivity of the benchmark product of fluorinated liquid cooling medium in the industry is approximately 0.06W / mK. If the fluorinated liquid liquid cooling medium (coolant) only uses one material structure, it is difficult to have the above-mentioned excellent properties at the same time. The structural design of the material molecule needs to have both low dielectric constant and high thermal conductivity, and low dielectric constant and high thermal conductivity are often contradictory and difficult to balance. At present, in the related technology, materials with high thermal conductivity are usually achieved by adding thermally conductive particles, but how to achieve long-term stability of thermally conductive particles in liquid cooling medium is a technical difficulty in the current industry.

[0064] In view of this, the embodiments of the present application aim at the shortcomings of current immersion cooling liquid working fluids in heat transfer and heat dissipation performance, which are specifically manifested in low thermal conductivity. Surface-treated nano-scale thermally conductive powder is added to a liquid based on fluorinated liquid, and a high-dispersion treatment is performed to prepare a dispersed and stable high-thermal conductivity liquid cooling working fluid for immersion liquid cooling and heat dissipation.

[0065] An embodiment of the present application provides a liquid cooling medium for liquid cooling of electronic equipment, comprising the following components in parts by mass: 94 to 100 parts of fluorinated liquid, 0 to 5 parts of thermally conductive powder, and 0 to 1 part of a stabilizer; wherein the thermally conductive powder is a thermally conductive powder treated with a surface treatment agent, and the surface treatment agent is a fluorine-containing silane coupling agent, and the liquid cooling can be immersion liquid cooling.

[0066] Fluorinated liquid itself has strong thermal conductivity and flow properties, low dielectric constant, stable chemical inertness, and system compatibility. It is currently widely used in immersion liquid cooling. As the name suggests, thermal conductive powder can enhance the thermal conductivity and heat transfer performance of materials. However, thermal conductive powder that has not been surface treated is prone to deposition and agglomeration when added to liquid cooling medium. If agglomerated substances appear in the liquid cooling medium, it will affect the thermal conductivity of the liquid cooling medium and cause its thermal conductivity to decrease, which is counterproductive. Therefore, the thermal conductive powder is treated with a surface treatment agent and dispersed at high speed with the aid of a stabilizer, so that the thermal conductive powder can be stabilized in the liquid cooling medium for a long time without agglomeration and deposition. Stabilizers can be adsorbed on the surface of nanopowders, increase steric hindrance and repulsion, prevent particle agglomeration and deposition, thereby improving the thermal conductivity and heat transfer performance of liquid cooling medium. The addition of stabilizers can increase the stability of thermal conductive powders.

[0067] Furthermore, the fluorinated liquid can be one or more of: hexafluoropropylene dimer, hexafluoropropylene trimer, perfluoroalkane, perfluoroketone, hydrofluoroether, perfluoropolyether, and hydrofluoroolefin. Fluorinated liquid has strong chemical stability, good insulation and dielectric properties, good thermal conductivity, and good fluidity, and can enhance the heat transfer of the system and improve the utilization rate of the liquid cooling medium. In the scenario of two-phase liquid cooling, the utilization rate of the phase change medium can also be improved.

[0068] Furthermore, the thermally conductive powder is a nano-scale powder with a particle size of less than 1000um, and can be one or more of: nano-silicon dioxide, nano-aluminum oxide, nano-zinc oxide, nano-boron nitride, nano-silicon carbide, nano-aluminum hydroxide, carbon nanotubes, graphene, and diamond; nano-scale thermally conductive powder can achieve higher thermal conductivity at a lower addition content due to its size effect, is easier to disperse in a fluorinated liquid system, and has good stability.

[0069] Further, the particle size of the thermally conductive powder is preferably: 1 to 500 nm. In some implementations, the particle size of the thermally conductive powder can be selected as: 1 nm to 100 nm, and the thermal conductivity of the thermally conductive powder particle size in this size range is better. The particle size of the thermally conductive powder will have a certain impact on the heat transfer and thermal conductivity of the liquid cooling medium. If a thermally conductive powder with a particle size that is too small is selected, for example, less than 1 nm, the specific surface area may be too large, the viscosity of the system increases significantly, and it cannot form a better thermal conduction path when dispersed in the system, and the thermal conductivity of the liquid cooling medium will not be significantly improved; if a thermally conductive powder with a particle size that is too large is selected, for example, greater than 500 nm, then in the process of adding the thermally conductive powder to the fluorinated liquid for high-speed dispersion, due to the large specific gravity of the particle size, it is not easy to disperse, and it is easy to produce agglomeration and deposition, then the thermal conductivity of the liquid cooling medium will be affected and reduced, therefore, the selection of a thermally conductive powder with a particle size in a certain size range can further improve the thermal conductivity of the liquid cooling medium.

[0070] It should be noted that since most thermal conductive powders are regular spheres, the above dimensions refer to the diameter of the thermal conductive powders. As for some non-spherical regular thermal conductive powders, the dimensions here refer to the maximum distance between the two end points on the maximum cross-section of the thermal conductive powders.

[0071] Furthermore, the surface treatment agent for the surface treatment of the thermally conductive powder can be: a fluorinated silane coupling agent, which is a type of liquid substance that builds a "molecular bridge" between the interface of the inorganic thermally conductive powder and the organic fluorinated liquid. One end of it contains a siloxane group that is friendly to the inorganic powder, and the siloxane group undergoes hydrolysis to form a chemical bond with the surface of the powder; the other end is a segment group with a carbon-fluorine skeleton, which forms an intermolecular force with the fluorinated liquid. Fluorinated silane coupling agents are products with mature market applications and can be purchased directly. For example, they include but are not limited to: one or more of trifluoropropane trimethoxysilane, heptadecafluorodecyl trimethoxysilane, and tridecafluorooctyl triethoxysilane.

[0072] Furthermore, in the process of high-speed dispersion of the thermally conductive powder, the stabilizer is a substance with a long alkyl chain group, which can coat the thermally conductive powder to a certain extent, increase steric hindrance and repulsion, and prevent particle agglomeration and deposition. Specifically, it can be selected from one or more of Tween 20, Tween 40, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and OP-10 dodecylphenol polyoxyethylene ether.

[0073] The present invention provides a method for preparing a liquid cooling medium, comprising the following steps:

[0074] S1. Spray and mix the liquid surface treatment agent and the thermal conductive powder in a mass ratio of 1:1. After mixing, wash with anhydrous ethanol and filter to remove excess surface treatment agent.

[0075] S2. Dry the thermally conductive powder in a drying oven at 40-80° C. for 1-1.5 hours to obtain a surface-treated thermally conductive powder.

[0076] S3, adding the stabilizer to the fluorinated liquid, and dispersing it with a disperser at room temperature; the speed of the disperser is 5000-10000 rpm, and the dispersing time is 20-40 minutes to obtain a mixed solution;

[0077] S4, adding the surface treated thermally conductive powder to the fluorinated liquid mixture, dispersing it with a disperser at room temperature, the speed of the disperser is 10000-20000 rpm, and the dispersion time is 0.5-1.5 hours to obtain a fluorinated liquid suspension. The fluorinated liquid suspension is the liquid cooling medium in the embodiment of the present application.

[0078] The liquid-cooling working fluid obtained in the embodiment of the present application is a fluid working fluid with high thermal conductivity. Since a certain proportion of nano-scale thermally conductive powder is added to the fluorinated liquid and dispersed to obtain a high thermal conductivity liquid-cooling working fluid, the liquid-cooling working fluid prepared in the embodiment of the present application has a thermal conductivity superior to that of general products in the industry. After the thermally conductive powder of a certain size is treated with a specific surface treatment agent, it is dispersed at a high speed with the assistance of a stabilizer, so that the thermally conductive powder in the liquid-cooling working fluid can maintain long-term stability without deposition and agglomeration, thereby enhancing the thermal conductivity and heat transfer performance of the liquid-cooling working fluid.

[0079] Example 1

[0080] A liquid cooling medium is composed of the following raw materials in parts by weight: 99.4 wt% of fluorinated liquid, 0.5 wt% of surface-treated nano-alumina powder with a particle size of 10 nm, and 0.1 wt% of a stabilizer.

[0081] The preparation method is:

[0082] S1. Spray and mix the liquid surface treatment agent heptadecafluorodecyltrimethoxysilane and alumina powder in a mass ratio of 1:1, wash with anhydrous ethanol after mixing, and then filter to remove excess surface treatment agent.

[0083] S2. Dry the alumina powder at 80°C for 1 hour to obtain surface-treated alumina powder.

[0084] S3, adding the stabilizer Tween 20 to the fluorinated liquid, dispersing it with a disperser at room temperature, the speed of the disperser is 8000 rpm, the dispersion time is 30 minutes, and a fluorinated liquid mixture is obtained;

[0085] S4. Add the nano-alumina powder obtained in step S2 to the fluoride liquid mixture, disperse it with a dispersant at room temperature, with a dispersing machine speed of 20,000 rpm for 1 hour to obtain a fluoride liquid suspension.

[0086] Example 2

[0087] A liquid cooling medium is composed of the following raw materials in parts by weight: 98.7 wt% of fluorinated liquid, 1 wt% of surface-treated nano-aluminum nitride with a particle size of 50 nm, and 0.3 wt% of a stabilizer.

[0088] The preparation method is:

[0089] S1. Spray and mix the liquid surface treatment agent tridecafluorooctyl triethoxysilane and aluminum nitride powder in a mass ratio of 1:1, wash with anhydrous ethanol after mixing, and then filter to remove excess surface treatment agent.

[0090] S2. Dry the aluminum oxide powder at 80° C. for 1 h to obtain surface-treated aluminum nitride powder.

[0091] S3, adding the stabilizer sodium dodecyl sulfate to the fluoride liquid, dispersing it with a disperser at room temperature, the speed of the disperser is 8000 rpm, the dispersion time is 30 minutes, and a fluoride liquid mixture is obtained;

[0092] S4. Add the nano aluminum nitride powder obtained in step S2 to the fluoride liquid mixture, disperse it with a dispersant at room temperature, with a dispersing machine speed of 20,000 rpm for 1 hour to obtain a fluoride liquid suspension.

[0093] Example 3

[0094] A liquid cooling medium is composed of the following raw materials in parts by weight: 94 wt% of fluorinated liquid, 5 wt% of surface-treated nano-alumina with a particle size of 100 nm, and 1 wt% of a stabilizer.

[0095] The preparation method is:

[0096] S1. Spray and mix the liquid surface treatment agent trifluoropropane trimethoxysilane and alumina powder in a mass ratio of 1:1, wash with alcohol after mixing, and then filter to remove excess surface treatment agent.

[0097] S2. Dry the alumina powder at 80°C for 1.5 hours to obtain surface-treated alumina powder.

[0098] S3, adding the stabilizer sodium dodecylbenzene sulfonate to the fluoridation liquid, dispersing it with a disperser at room temperature, the speed of the disperser is 10000 rpm, the dispersion time is 40 min, and a fluoridation liquid mixture is obtained;

[0099] S4. Add the nano-alumina powder obtained in step S2 to the fluoride liquid mixture, disperse it with a dispersant at room temperature, with a dispersing machine speed of 20,000 rpm for 1.5 hours to obtain a fluoride liquid suspension.

[0100] Example 4

[0101] A liquid cooling medium is composed of the following raw materials in parts by weight: 99.8 wt% of fluorinated liquid, 0.1 wt% of surface-treated nano-aluminum nitride with a particle size of 100 nm, and 0.1 wt% of a stabilizer.

[0102] The preparation method is:

[0103] S1. Spray and mix the liquid surface treatment agent heptadecafluorodecyltrimethoxysilane and aluminum nitride powder in a mass ratio of 1:1, wash with alcohol after mixing, and then filter to remove excess surface treatment agent.

[0104] S2. Dry the aluminum oxide powder at 80° C. for 1 h to obtain surface-treated aluminum nitride powder.

[0105] S3, adding the stabilizer Tween 40 to the fluorinated liquid, dispersing it with a disperser at room temperature, the speed of the disperser is 8000 rpm, the dispersion time is 20 minutes, and a fluorinated liquid mixture is obtained;

[0106] S4. Add the nano aluminum nitride powder obtained in step S2 to the fluoride liquid mixture, disperse it with a dispersant at room temperature, with a dispersing machine speed of 15000 rpm for 1 hour to obtain a fluoride liquid suspension.

[0107] Example 5

[0108] A liquid cooling medium is composed of the following raw materials in parts by weight: 95 wt% of fluorinated liquid, 5 wt% of surface-treated nano-alumina with a particle size of 300 nm, and 0.5 wt% of a stabilizer.

[0109] The preparation method is:

[0110] S1. Spray and mix the liquid surface treatment agent tridecafluorooctyl triethoxysilane and alumina powder in a mass ratio of 1:1, wash with alcohol after mixing, and then filter to remove excess surface treatment agent.

[0111] S2. Dry the alumina powder at 80°C for 1 hour to obtain surface-treated alumina powder.

[0112] S3, adding the stabilizer Tween 40 to the fluorinated liquid, dispersing it with a disperser at room temperature, the speed of the disperser is 8000 rpm, the dispersion time is 30 minutes, and a fluorinated liquid mixture is obtained;

[0113] S4. Add the nano-alumina powder obtained in step S2 to the fluoride liquid mixture, disperse it with a dispersant at room temperature, with a dispersing machine speed of 20,000 rpm for 1 hour to obtain a fluoride liquid suspension.

[0114] Comparative Example 1

[0115] The comparison component is the industry's hexafluoropropylene dimer fluorinated liquid product, to which no other components are added and no chemical treatment is performed.

[0116] In order to further illustrate that the fluorinated liquid cooling medium provided in the embodiments of the present application has good thermal conductivity, heat transfer performance and stability, the fluorinated liquid provided in Examples 1 to 5 and Comparative Example 1 was subjected to stability tests and thermal conductivity tests. For the convenience of description, the test samples in Examples 1 to 5 are respectively recorded as Samples 1 to 5, and the test samples in Comparative Example 1 are recorded as Comparative Samples. Among them, the steps of the stability test include: taking out 10 ml of Samples 1 to 6 and Comparative Samples respectively in a test tube and letting them stand for 48 hours to observe whether the liquid is clear and whether there are any particles precipitated. The thermal conductivity test includes: in a hot wire method thermal conductivity tester, respectively testing the thermal conductivity values ​​of Samples 1 to 5 and the Comparative Samples under normal temperature and pressure conditions.

[0117] After testing, the test results shown in Table 1 can be obtained:

[0118] Table 1 Performance test results of samples 1-5 and comparative samples

[0119]

[0120] It can be seen from Table 1 that the thermal conductivity coefficients of Samples 1 to 5 are all greater than 0.06W / (mK), which means that the thermal conductivity of the fluorinated liquid obtained by using the component ratio and preparation method in the embodiments of the present application is improved to a certain extent compared with the simple fluorinated liquid; the stability of Samples 1 to 5 is also relatively high, the liquid is clear, and there is no obvious particle precipitation.

[0121] In the embodiment of the present application, fluorinated liquid is used as the base liquid, and a certain proportion of nano-scale thermal conductive powder is added to the liquid. After dispersion, a high thermal conductivity liquid cooling medium is prepared. The liquid cooling medium prepared in the embodiment of the present application has the thermal conductivity of general products in the industry, and due to the low dielectric constant, stable chemical inertness, and system compatibility of the fluorinated liquid, in addition to being applied to the above Figure 1In addition to the data center, it can also be widely used in new energy immersion (such as new energy automobile field), high-voltage switchgear, personal computer, terminal equipment and other fields that require efficient heat dissipation or other electronic equipment, such as high-voltage distribution cabinet, switchgear, circuit breaker, etc. In the embodiment of the present application, a thermal conductive powder of a certain size and a certain proportion is added to the fluorinated liquid, and after being treated with a surface treatment agent, it is dispersed at a high speed under a stabilizer, so that the thermal conductive powder can maintain long-term stable performance in the liquid cooling medium, and is not prone to deposition and agglomeration. Its thermal conductivity has been significantly improved compared with the relevant technology, and the system is stable, meeting the requirements of application reliability such as no agglomeration and no deposition.

[0122] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, refer to the relevant description of other embodiments.

[0123] It should be noted that, for the above-mentioned method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0124] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative.

[0125] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid cooling medium, characterized in that: The liquid cooling medium comprises the following components in parts by mass: 94 to 100 parts of fluorinated liquid, 0 to 5 parts of thermally conductive powder, and 0 to 1 part of a stabilizer; the thermally conductive powder is thermally conductive powder treated with a surface treatment agent, and the surface treatment agent is a fluorine-containing silane coupling agent.

2. The liquid cooling medium according to claim 1, characterized in that: The particle size of the thermally conductive powder is 1-500 nm.

3. The liquid cooling medium according to claim 2, characterized in that: The particle size of the thermally conductive powder is 1 nm to 100 nm.

4. The liquid cooling medium according to any one of claims 1 to 3, characterized in that: The fluorinated liquid is one or more of hexafluoropropylene dimer, hexafluoropropylene trimer, perfluoroalkane, perfluoroketone, hydrofluoroether, perfluoropolyether and hydrofluoroolefin.

5. The liquid cooling medium according to any one of claims 1 to 4, characterized in that: The thermally conductive powder is one or more of nano silicon dioxide, nano aluminum oxide, nano zinc oxide, nano boron nitride, nano silicon carbide, nano aluminum hydroxide, carbon nanotube, graphene, and diamond.

6. The liquid cooling medium according to any one of claims 1 to 5, characterized in that: The surface treatment agent is one or more of trifluoropropane trimethoxysilane, heptadecafluorodecyl trimethoxysilane and tridecafluorooctyl triethoxysilane.

7. A method for preparing a liquid cooling medium, characterized in that: The preparation method comprises the following steps: S1. Spray and mix the liquid surface treatment agent and the thermal conductive powder in a mass ratio of 1:1, wash with anhydrous ethanol after mixing, and filter to remove excess surface treatment agent; S2, drying the thermally conductive powder at 40-80° C. for 1-1.5 hours to obtain a surface-treated thermally conductive powder; S3, adding the stabilizer to the fluorinated liquid, and dispersing it with a disperser at room temperature; the speed of the disperser is 5000-10000 rpm, and the dispersing time is 20-40 minutes to obtain a fluorinated liquid mixture; S4. Add the surface treated thermally conductive powder into the fluorinated liquid mixture, and disperse it with a disperser at room temperature. The speed of the disperser is 10000-20000 rpm, and the dispersion time is 0.5-1.5 hours to obtain the liquid cooling medium.

8. The preparation method according to claim 7, characterized in that: The particle size of the thermally conductive powder is 1 to 500 nm.

9. The preparation method according to claim 7 or 8, characterized in that: The fluorinated liquid is one or more of hexafluoropropylene dimer, hexafluoropropylene trimer, perfluoroalkane, perfluoroketone, hydrofluoroether, perfluoropolyether and hydrofluoroolefin.

10. The preparation method according to any one of claims 7 to 9, characterized in that: The thermally conductive powder is one or more of nano silicon dioxide, nano aluminum oxide, nano zinc oxide, nano boron nitride, nano silicon carbide, nano aluminum hydroxide, carbon nanotube, graphene and diamond.

11. The preparation method according to any one of claims 7 to 10, characterized in that: The surface treatment agent is one or more of trifluoropropane trimethoxysilane, heptadecafluorodecyl trimethoxysilane and tridecafluorooctyl triethoxysilane.

12. The preparation method according to any one of claims 7 to 11, characterized in that The stabilizer is one or more of Tween 20, Tween 40, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and OP-10 dodecylphenol polyoxyethylene ether.

13. An electronic device, characterized in that The electronic device comprises a shell, a circuit board is arranged in the shell, and electronic devices are arranged on the circuit board. The liquid-cooling medium as claimed in any one of claims 1 to 6 or the liquid-cooling medium obtained by the preparation method as claimed in any one of claims 7 to 12 is arranged in the shell, and the electronic devices are immersed or partially immersed in the liquid-cooling medium.

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