Three-phase nanofluid coolant

Abstract

The invention discloses a three-phase nanofluid coolant which is suitable for cold plate heat dissipation and comprises a cooling liquid which is suitable for being converted from a liquid phase to a gas phase after absorbing heat and being converted from the gas phase to the liquid phase after releasing heat; the heat conductivity of the nano heat-conducting filler is greater than or equal to 100W / (m.K). The heat transfer efficiency of the fluid coolant is improved through the arranged nanometer heat conduction filler, so that heat is more easily transferred to the fluid coolant from the cold plate; and by arranging cooling liquid with different boiling points, the heat dissipation efficiency can be improved, the risk that the heat dissipation efficiency is poor due to the fact that the viscosity in the fluid cooling agent is too large during phase change can be reduced while the heat dissipation working temperature of the cold plate is increased, and therefore the service life is further prolonged, the use performance is further improved, and the market competitiveness is further improved.

Description

Technical Field

[0001] The present application relates to the field of refrigeration technology, and in particular to a three-phase nanofluid coolant. Background Art

[0002] With the surge in global computing demand and the advancement of energy-saving and emission-reduction policies, traditional cooling methods including air cooling, heat pipe cooling, and water cooling face problems such as low cooling efficiency, high noise, and high maintenance costs when cooling data centers and electronic equipment.

[0003] Among them, phase change refrigerant is a material that uses the property of a substance to absorb and release heat during a phase change process to achieve refrigeration. In the field of refrigeration and thermal management, phase change refrigerant, as a core working fluid, realizes heat transfer through a phase change cycle between liquid and gas, and is therefore widely used in data centers, electronic equipment, medical equipment, food cold chain, automotive air conditioning, and industrial processes. However, the phase separation phenomenon that exists in existing phase change refrigerants during long-term use affects their performance and stability, further reducing the cold storage or heat dissipation capacity of the phase change material, and having poor stability during multiple cycles. On the other hand, due to the risk of uneven temperature in the refrigerant after the phase change, while reducing the heat transfer performance, the heat dissipation efficiency of the phase change refrigerant is reduced. Such shortcomings limit the widespread application of phase change refrigerants.

[0004] Therefore, the industry urgently needs to prepare a phase change refrigerant with good heat transfer efficiency and superior heat dissipation performance to adapt to the application in the field of refrigeration and thermal management with the growing demand for heat dissipation. Summary of the Invention

[0005] One purpose of the present application is to provide a three-phase nanofluid coolant, which is beneficial to improving the heat dissipation efficiency of the coolant, while enhancing performance and service life, improving temperature uniformity, and reducing the risk of equipment damage due to overheating.

[0006] Another object of the present application is to provide a three-phase nanofluid coolant, which is beneficial to improving the heat dissipation working temperature of the coolant, and can also reduce the viscosity of the fluid coolant, increase the fluidity and circulation stability of the coolant.

[0007] To achieve the above objectives, the technical solution adopted in this application is: a three-phase nanofluid coolant suitable for cold plate heat dissipation, comprising:

[0008] A coolant adapted to transform from a liquid phase to a gas phase after absorbing heat and from a gas phase to a liquid phase after releasing heat; and a nano-thermal conductive filler dispersed in the coolant, wherein the thermal conductivity of the nano-thermal conductive filler is ≥100 W / (m·K).

[0009] In some embodiments, the coolant includes a first coolant and a second coolant with different boiling points, the boiling point of the first coolant is ≤65° C., and the boiling point of the second coolant is greater than the boiling point of the first coolant.

[0010] In some embodiments, the mass ratio of the coolant to the nano-thermal conductive filler is (1000-10):1, and the mass ratio of the first coolant to the second coolant is (10-3):1.

[0011] In some embodiments, the first coolant is a fluorine-containing compound with a boiling point ≤65°C, and the second coolant is a fluorine-containing compound with a boiling point ≥75°C, or an ether, or a ketone compound; the viscosity of the first coolant is ≤5mPa·s, and the viscosity of the second coolant is ≤20mPa·s.

[0012] In some embodiments, the first coolant is one or more of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, nonafluorobutyl methyl ether and methyl nonafluorobutyl ether, perfluoropolyether, perfluoroamine, perfluoroketone, perfluoroalkane, and perfluoroolefin; the second coolant is one or more of butanone, cyclohexanone, ethylene glycol dimethyl ether, nonafluorobutyl ethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxybutane and 2-(trifluoromethyl)-3-ethoxydodecafluorohexane, perfluoropolyether, perfluoroamine, perfluoroketone, perfluoroalkane, and perfluoroolefin.

[0013] In some embodiments, the thermally conductive nanofiller is one or more of modified boron nitride nanoparticles, modified graphene, modified carbon nanotubes, and metal nanoparticles.

[0014] In some embodiments, the particle size of the nano thermally conductive filler is ≤1 μm.

[0015] In some embodiments, the steps for preparing the nano thermally conductive filler are:

[0016] S100, dissolving a thermally conductive filler and a silane coupling agent in anhydrous ethanol, and subjecting the mixture to a high-temperature reaction to obtain a first mixture;

[0017] S200 , washing away unreacted raw materials and by-products in the first mixture by repeated centrifugal separation and ultrasonic dispersion operations to obtain the nano thermally conductive filler.

[0018] In some embodiments, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and heptadecafluorodecyltrimethoxysilane.

[0019] In some embodiments, the coolant further comprises one or more of a co-solvent, a coupling agent, an antioxidant, a dispersant, a flame retardant, and a defoaming agent.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The present application increases the heat transfer efficiency of the nanofluid coolant by providing a nano-thermal conductive filler, making it easier for heat to be transferred from the cold plate to the fluid coolant, thereby enhancing the stability of temperature transfer and the stability of use. On the other hand, the coolant prepared by mixing components with different boiling points and good compatibility can help reduce the risk of phase separation and improve heat dissipation efficiency.

[0022] (2) The mixed coolant provided in the present application can also increase the heat dissipation operating temperature of the cold plate while reducing the risk of poor heat dissipation efficiency caused by excessive viscosity in the fluid coolant during phase change, thereby enhancing stability during cyclic use, thereby further enhancing the service life, performance and market competitiveness of the fluid coolant.

[0023] (3) This application mainly uses hydrofluoroether compounds, which have zero ozone depletion potential and low global warming potential, which is beneficial to environmental protection. DETAILED DESCRIPTION

[0024] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0025] As used herein, the term "prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0026] When an amount, concentration or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range includes its end values ​​and all integers and fractions within the range.

[0027] Approximating terms in the specification and claims are used to modify a quantity to indicate that the invention is not limited to that specific quantity and includes acceptable modifications close to that quantity that do not result in a change in the relevant basic function. Accordingly, the use of "about," "approximately," or the like to modify a numerical value indicates that the invention is not limited to that exact numerical value. In some instances, approximating terms may correspond to the precision of the instrument used to measure the value. In the specification and claims of this application, range definitions may be combined and / or interchanged, and unless otherwise indicated, such ranges include all subranges contained therein.

[0028] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0029] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0030] To achieve the above objectives, the technical solution adopted in this application is: a three-phase nanofluid coolant suitable for cold plate heat dissipation, comprising:

[0031] A coolant that is suitable for changing from a liquid phase to a gas phase after absorbing heat, and changing from a gas phase to a liquid phase after releasing heat; and a nano-thermal conductive filler dispersed in the coolant, wherein the thermal conductivity of the nano-thermal conductive filler tested at room temperature is ≥100W / (m·K). The present application is provided with a nano-thermal conductive filler and a coolant, wherein the nano-thermal conductive filler is dispersed in a nanofluid coolant. Due to its own high thermal conductivity, while it is beneficial to increase the heat transfer efficiency of the nanofluid coolant, it can reduce the thermal resistance during the phase change process, thereby making the latent heat absorption more sufficient during the phase change process, thereby maintaining the stability and uniformity of the temperature of the heat dissipation system. It can be understood that the phase change coolant can reduce the thermal stress of the heat dissipation equipment, making it easier for heat to be transferred from the cold plate, thereby enhancing the stability during temperature transfer and the stability of use. It can also reduce the risk of equipment damage due to overheating, thereby extending the service life of the heat dissipation equipment.

[0032] It will be understood that the thermal conductivity of the nano-thermal conductive filler tested at room temperature in the present application may also be ≥400 W / (m·K), or ≥600 W / (m·K), or ≥700 W / (m·K), or ≥800 W / (m·K), or ≥900 W / (m·K), or ≥1000 W / (m·K), or ≥1500 W / (m·K).

[0033] In some embodiments, the coolant includes a first coolant and a second coolant having different boiling points, wherein the boiling point of the first coolant is ≤65°C, and the boiling point of the second coolant is greater than the boiling point of the first coolant. It is worth noting that the provision of coolants with different boiling points and good compatibility helps reduce the risk of phase separation in the coolant, thereby improving heat dissipation efficiency and the stability of the heat dissipation system. Furthermore, since the viscosity of the remaining liquid that has not undergone a phase change increases during the phase change, which affects the dissipation of heat from the cold plate, the provision of a second coolant with a higher boiling point is used to maintain the viscosity of the remaining liquid, increasing its fluidity and facilitating heat dissipation.

[0034] In some embodiments, the mass ratio of the coolant to the nano-thermal conductive filler is (1000-10):1. The added nano-thermal conductive filler increases the heat transfer efficiency of the nano-fluid coolant, making it easier for heat to be transferred from the cold plate to the nano-fluid coolant, and is beneficial for absorbing latent heat during the phase change of the coolant to maintain the stability and uniformity of the temperature of the heat dissipation system. It can be understood that when the mass of the added nano-thermal conductive filler is too small, the heat transfer efficiency of the nano-fluid coolant is poor, thereby reducing the heat diffusion rate on the cold plate, thereby reducing the heat dissipation efficiency of the nano-fluid coolant; and when the mass of the added nano-thermal conductive filler is too large, the viscosity of the nano-fluid coolant is further increased, making it difficult for heat to dissipate, thereby reducing the heat dissipation efficiency of the nano-fluid coolant. Therefore, selecting an appropriate mass of nano-thermal conductive filler is beneficial to maintaining the good heat transfer efficiency of the nano-fluid coolant while also maintaining good heat dissipation efficiency.

[0035] In some embodiments, the mass ratio of the first coolant to the second coolant is (10-3):1. Providing a first coolant and a second coolant with different boiling points can improve heat dissipation efficiency. While increasing the cold plate's heat dissipation operating temperature, it can also reduce the risk of reduced heat dissipation efficiency due to excessive viscosity in the nanofluid coolant during phase change, further enhancing the coolant's service life, performance, and market competitiveness. It is worth noting that when the mass of the second coolant used is too small, when the first coolant is in a gaseous state, the mixture of the second coolant, the remaining unphased first coolant, and the nano-thermal conductive filler has a high viscosity, which is not conducive to heat transfer on the cold plate, thereby reducing the heat dissipation efficiency of the nanofluid coolant. When the mass of the second coolant used is too large, the content of the first coolant that undergoes phase change is low, resulting in a lower degree of phase change in the nanofluid coolant overall, thereby reducing heat dissipation efficiency. Therefore, selecting an appropriate mass of the second coolant can maintain the good heat transfer efficiency of the nanofluid coolant while also maintaining good heat dissipation efficiency.

[0036] In some embodiments, the first coolant is a fluorine-containing compound with a boiling point ≤65°C, and the second coolant is a fluorine-containing compound, ether, or ketone compound with a boiling point ≥75°C. The viscosity of the first coolant is ≤5mPa·s, and the viscosity of the second coolant is ≤20mPa·s. Using first and second coolants with different boiling points improves heat dissipation efficiency and, while increasing the cold plate's operating temperature, reduces the risk of poor heat dissipation efficiency due to excessive viscosity in the nanofluid coolant during phase change, thereby further enhancing service life, performance, and market competitiveness.

[0037] Among them, fluorine-containing compounds have high thermal conductivity and high heat capacity, can quickly absorb and transfer heat, and maintain stable operation of equipment. Perfluorocarbons and hydrofluoroethers, in particular, excel in thermal conductivity due to their unique chemical structure and physical properties. It can be understood that hydrofluoroether compounds are a type of material that does not contain halogens other than fluorine and has zero ozone depletion potential. They are an ideal substitute for chlorofluorocarbons and are environmentally friendly. Furthermore, hydrofluoroether compounds generally have low surface tension and viscosity, and have the advantages of being volatile and leaving no residue. When used in phase change coolants, they help improve heat transfer efficiency. On the one hand, hydrofluoroether compounds have good thermal stability and can maintain stable heat dissipation performance during repeated phase changes. On the other hand, hydrofluoroether compounds are non-toxic and non-flammable during use, are safe to use, and have little impact on the environment and human health.

[0038] It's worth noting that ketone compounds, due to the polarity of the ketone group, have high boiling points and solubility, resulting in increased stability and inertness. Furthermore, ketone compounds also have excellent heat transfer properties, making them suitable for coolant applications. It's understandable that ethers or ketones have a certain degree of compatibility with hydrofluoroethers, reducing the risk of phase separation after mixing and improving the coolant's stability during use and recycling.

[0039] Furthermore, the use of a first coolant with a larger content and lower viscosity is beneficial to improving the overall fluidity of the coolant, and reducing the viscosity is beneficial to heat conduction. At the same time, the combined use of a second coolant with a smaller content and lower viscosity also helps to reduce the viscosity of the remaining liquid when the first coolant undergoes a phase change, thereby maintaining good heat dissipation performance throughout the entire process of cooling the cold plate.

[0040] In some embodiments, the first coolant is one or more of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, nonafluorobutyl methyl ether, methyl nonafluorobutyl ether, perfluoropolyether, perfluoroamine, perfluoroketone, perfluoroalkane, and perfluoroolefin. Such hydrofluoroether compounds have low global warming potential and zero ozone depletion potential, and are environmentally friendly. On the one hand, the low viscosity and low surface tension of such hydrofluoroether compounds help improve heat transfer efficiency; on the other hand, since such hydrofluoroether compounds can undergo phase change upon heating, they are suitable for a variety of applications with high heat dissipation requirements, thus having broad application prospects.

[0041] In some embodiments, the second coolant is one or more of butanone, cyclohexanone, ethylene glycol dimethyl ether, nonafluorobutyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxybutane and 2-(trifluoromethyl)-3-ethoxydodecafluorohexane, perfluoropolyether, perfluoroamine, perfluoroketone, perfluoroalkane, and perfluoroolefin. Among them, such ketone compounds have high chemical stability and inertness, which improves the stability and safety of the coolant. On the other hand, since ketone compounds have good material compatibility, they can further improve the compatibility between the components in the coolant and further reduce the risk of phase separation. When hydrofluoroether compounds and ether compounds are used in combination, since ether compounds generally have low surface tension, viscosity and good heat transfer properties, they are conducive to further improving the heat transfer efficiency of the coolant and the fluid coolant.

[0042] Among them, when a hydrofluoroether compound with a higher boiling point is selected as the second coolant, it has good compatibility with the first coolant, further reducing the risk of phase separation in the coolant and the fluid coolant, thereby increasing the stability of use and the stability during multiple cycles.

[0043] In some embodiments, the nano-thermal conductive filler is one or more of modified boron nitride nanoparticles, modified graphene, modified carbon nanotubes, and metal nanoparticles. It is understood that such nano-thermal conductive fillers have excellent thermal conductivity and, when added to the coolant, further enhance heat transfer efficiency, facilitating heat transfer from the cold plate. Furthermore, due to the enhanced heat transfer properties of the nanofluid coolant, the hydrofluoroether compound is more susceptible to heat and phase transition, thereby improving heat dissipation performance.

[0044] Furthermore, when modified boron nitride nanoparticles are added as thermally conductive nanofillers, due to their non-conductive nature, they can be used in immersion cooling systems, reducing the risk of leakage that could short-circuit or even damage electronic equipment, thereby lowering maintenance costs and environmental pollution. Therefore, the use of non-conductive modified boron nitride nanoparticles can further improve the safety and operational stability of cooling systems.

[0045] In some embodiments, the particle size of the nano thermal conductive filler is ≤1 μm. It is understood that nano-particle thermal conductive fillers are less likely to agglomerate during use, so when used in nanofluid coolants, heat transfer is more uniform, further improving the performance of the nanofluid coolant.

[0046] In some embodiments, the steps for preparing the nano thermally conductive filler are:

[0047] S100, dissolving a thermally conductive filler and a silane coupling agent in anhydrous ethanol, and subjecting the mixture to a high-temperature reaction to obtain a first mixture;

[0048] S200 , washing away unreacted raw materials and by-products in the first mixture by repeated centrifugal separation and ultrasonic dispersion operations to obtain the nano thermally conductive filler.

[0049] The preparation steps for modifying the nano thermally conductive filler provided in the present application have the advantages of a simple preparation method, fewer operation steps, and higher production efficiency, which is conducive to large-scale production process.

[0050] In some embodiments, the steps for preparing the nano thermally conductive filler are:

[0051] S100, placing a thermally conductive filler in anhydrous ethanol and performing ultrasonic treatment for 10 minutes to 30 minutes to obtain a first solution;

[0052] S200, placing the first solution into a mixed solution of a silane coupling agent and anhydrous ethanol, stirring and reacting for 1 hour to 3 hours to obtain a first mixture;

[0053] S300, by centrifuging the first mixture, washing and drying the solid matter obtained by the centrifugation, to obtain a modified thermally conductive filler. The preparation steps for modifying the nano thermally conductive filler provided by the present application have the advantages of a simple preparation method, fewer operating steps, and higher production efficiency, which is conducive to large-scale production process. It is worth mentioning that, since the nano thermally conductive filler in the present application is dispersed in the first coolant and the second coolant, the dispersion performance of the nano thermally conductive filler has a more important influence on the performance of the three-phase nanofluid coolant. Therefore, the use of a silane coupling agent to modify the nano thermally conductive filler in the present application is conducive to increasing the compatibility of the nano thermally conductive filler with the remaining components, so that the nano thermally conductive filler is more evenly distributed in the coolant, thereby making the heat transfer on the cold plate faster and more uniform, and the heat dissipation effect better.

[0054] In some embodiments, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane (KH-550), 3-glycidyloxypropyltrimethoxysilane (KH-560), γ-methacryloxypropyltrimethoxysilane (KH-570), and heptadecafluorodecyltrimethoxysilane. KH-550 contains two functional groups, amino and ethoxy, which allow the surface of the nano-thermal conductive filler to have amino groups, thereby facilitating hydrogen bonding and other interactions between the nano-thermal conductive filler and polar parts such as fluorine atoms in hydrofluoroether compounds, further enhancing the adhesion between the nano-thermal conductive filler and the hydrofluoroether compounds and enhancing the dispersion performance of the nano-thermal conductive filler. The epoxy groups on the surface of the nano-thermal conductive filler obtained by KH-560 treatment can form hydrogen bonds and other interactions with polar groups in hydrofluoroether compounds, ketones, and ethers, thereby enhancing the dispersion performance of the nano-thermal conductive filler. Treatment with KH-570 can improve the dispersibility of the nano-thermal conductive filler in the organic medium.

[0055] It is worth mentioning that since the fluorinated alkyl chains (such as -CF2- and -CF3) in heptafluorodecyltrimethoxysilane are similar to the fluorinated structures in hydrofluoroether compounds, the modified nano-thermal conductive filler has a fluorocarbon chain, which reduces the interfacial tension through the principle of like dissolves like, reduces the risk of agglomeration of the nano-thermal conductive filler, and further significantly improves the dispersion uniformity and stability of the nano-thermal conductive filler.

[0056] It is understandable that the modified nano thermally conductive filler can have good compatibility and dispersibility with hydrofluoroether compounds, thereby reducing the phase separation phenomenon produced after multiple cyclic phase changes and improving the stability and service life of the nanofluid coolant.

[0057] In some embodiments, the coolant further comprises one or more of a cosolvent, a coupling agent, an antioxidant, a dispersant, a flame retardant, and a defoaming agent. Among these, the cosolvent, coupling agent, and dispersant can enhance the compatibility between the components of the nanofluid coolant, prevent filler agglomeration, and evenly disperse the components, thereby improving overall stability. The antioxidant can prevent the nanofluid coolant from being oxidized during high temperature or long-term use, thereby extending the service life and stability of the nanofluid coolant. The flame retardant can improve flame retardancy, reduce the risk of fire, and further enhance safety when used in high temperature or flammable environments. The defoaming agent can help reduce the formation of bubbles during recycling, reduce air lock, and improve the coolant's fluidity and heat transfer efficiency.

[0058] Example 1

[0059] A three-phase nanofluid coolant comprises 80 wt.% of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (HFE-347), 15 wt.% of ethylene glycol dimethyl ether, 4 wt.% of modified boron nitride nanoparticles (BN), 0.3 wt.% of an antioxidant, 0.3 wt.% of an antioxidant, 0.2 wt.% of a flame retardant, and 0.2 wt.% of a defoamer. The silane coupling agent used for the modification is KH-560.

[0060] Example 2

[0061] The difference between Example 2 and Example 1 is that the mass fraction of HFE-347 is 75 wt.%, and the mass fraction of ethylene glycol dimethyl ether is 20 wt.%.

[0062] Example 3

[0063] The difference between Example 3 and Example 1 is that the mass fraction of HFE-347 is 85 wt.%, and the mass fraction of ethylene glycol dimethyl ether is 10 wt.%.

[0064] Example 4

[0065] The difference between Example 4 and Example 1 is that it includes 80 wt.% of HFE-347 by mass, 15 wt.% of ethylene glycol dimethyl ether by mass, 4 wt.% of modified graphene by mass, 0.3 wt.% of antioxidant by mass, 0.3 wt.% of antioxidant by mass, 0.2 wt.% of flame retardant by mass, and 0.2 wt.% of defoaming agent by mass.

[0066] Example 5

[0067] The difference between Example 5 and Example 1 is that it includes 80 wt.% of HFE-347 by mass, 15 wt.% of ethylene glycol dimethyl ether by mass, 4 wt.% of modified carbon nanotubes (CNTs) by mass, 0.3 wt.% of antioxidant by mass, 0.3 wt.% of antioxidant by mass, 0.2 wt.% of flame retardant by mass, and 0.2 wt.% of defoaming agent by mass.

[0068] Example 6

[0069] The difference between Example 6 and Example 1 is that it includes 80 wt.% of HFE-347 by mass, 15 wt.% of butanone by mass, 4 wt.% of BN by mass, 0.3 wt.% of antioxidant by mass, 0.3 wt.% of antioxidant by mass, 0.2 wt.% of flame retardant by mass, and 0.2 wt.% of defoaming agent by mass.

[0070] Example 7

[0071] The difference between Example 7 and Example 1 is that it includes 80 wt.% of HFE-347 by mass, 15 wt.% of nonafluorobutyl ether by mass, 4 wt.% of BN by mass, 0.3 wt.% of antioxidant by mass, 0.3 wt.% of antioxidant by mass, 0.2 wt.% of flame retardant by mass, and 0.2 wt.% of defoaming agent by mass.

[0072] Example 8

[0073] The difference between Example 8 and Example 1 is that it includes 80wt.% HFE-347 by mass, 15wt.% 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxybutane (HFE-7300) by mass, 4wt.% BN by mass, 0.3wt.% antioxidant by mass, 0.3wt.% antioxidant by mass, 0.2wt.% flame retardant by mass, and 0.2wt.% defoaming agent by mass.

[0074] Example 9

[0075] The difference between Example 9 and Example 1 is that it includes 82 wt.% of HFE-347 by mass, 16 wt.% of ethylene glycol dimethyl ether by mass, 1 wt.% of BN by mass, 0.3 wt.% of antioxidant by mass, 0.3 wt.% of antioxidant by mass, 0.2 wt.% of flame retardant by mass, and 0.2 wt.% of defoaming agent by mass.

[0076] Example 10

[0077] The difference between Example 10 and Example 1 is that it includes 78wt.% of HFE-347 by mass, 13wt.% of ethylene glycol dimethyl ether by mass, 8wt.% of BN by mass, 0.3wt.% of antioxidant by mass, 0.3wt.% of antioxidant by mass, 0.2wt.% of flame retardant by mass, and 0.2wt.% of defoaming agent by mass.

[0078] Example 11

[0079] The difference between Example 11 and Example 1 is that the silane coupling agent used for modification is KH-550.

[0080] Example 12

[0081] The difference between Example 12 and Example 1 is that the silane coupling agent used for modification is KH-570.

[0082] Example 13

[0083] The difference between Example 13 and Example 1 is that the silane coupling agent used for modification is heptadecafluorodecyltrimethoxysilane.

[0084] Comparative Example 1

[0085] The difference between Comparative Example 1 and Example 1 is that the mass fraction of HFE-347 is 80 wt.%, and the mass fraction of ethylene glycol dimethyl ether is 20 wt.%.

[0086] Comparative Example 2

[0087] The difference between Comparative Example 2 and Example 1 is that the mass fraction of HFE-347 is 100 wt.%.

[0088] Comparative Example 3

[0089] The difference between Comparative Example 3 and Example 1 is that no silane coupling agent is used to modify BN.

[0090] Performance evaluation

[0091] The nanofluid coolants prepared in Examples 1 to 10 and Comparative Examples 1 and 2 were used to dissipate heat from a Dell R750XS rack server, and the temperature changes of the CPU components after running for 12 hours and 48 hours were observed. Table 1: Performance test of nanofluid coolant

[0092] It is understandable that by providing coolants with different boiling points and adding modified nano-thermal conductive fillers, the heat dissipation performance of the nanofluid coolant and its stability during long-term cyclic use can be better improved in practical applications.

[0093] The above describes the basic principles, main features, and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and the specification merely illustrate the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. These changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A three-phase nanofluid coolant suitable for cold plate heat dissipation, characterized in that: include: a coolant adapted to change from a liquid phase to a vapor phase upon absorbing heat and from a vapor phase to a liquid phase upon releasing heat; and a nano thermally conductive filler dispersed in the coolant, wherein the thermal conductivity of the nano thermally conductive filler is ≥100 W / (m·K).

2. The coolant according to claim 1, wherein The coolant includes a first coolant and a second coolant with different boiling points. The boiling point of the first coolant is ≤65° C., and the boiling point of the second coolant is greater than the boiling point of the first coolant.

3. The coolant according to claim 2, wherein The mass ratio of the coolant to the nano-thermal conductive filler is (1000-10):1, and the mass ratio of the first coolant to the second coolant is (10-3):

1.

4. The coolant according to claim 2, wherein The first coolant is a fluorine-containing compound with a boiling point of ≤65°C, and the second coolant is a fluorine-containing compound with a boiling point of ≥75°C, or an ether, or a ketone compound; The viscosity of the first coolant is ≤5 mPa·s, and the viscosity of the second coolant is ≤20 mPa·s.

5. The coolant according to claim 2, wherein The first coolant is one or more of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, nonafluorobutyl methyl ether and methyl nonafluorobutyl ether, perfluoropolyether, perfluoroamine, perfluoroketone, perfluoroalkane, and perfluoroolefin; the second coolant is one or more of butanone, cyclohexanone, ethylene glycol dimethyl ether, nonafluorobutyl ethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxybutane and 2-(trifluoromethyl)-3-ethoxydodecafluorohexane, perfluoropolyether, perfluoroamine, perfluoroketone, perfluoroalkane, and perfluoroolefin.

6. The coolant according to any one of claims 1 to 5, characterized in that The nano thermal conductive filler is one or more of modified boron nitride nanoparticles, modified graphene, modified carbon nanotubes and metal nanoparticles.

7. The coolant according to claim 6, characterized in that The particle size of the nano thermal conductive filler is ≤1 μm.

8. The coolant according to claim 6, wherein The preparation steps of the nano thermal conductive filler are: S100, dissolving a thermally conductive filler and a silane coupling agent in anhydrous ethanol, and subjecting the mixture to a high-temperature reaction to obtain a first mixture; S200 , washing away unreacted raw materials and by-products in the first mixture by repeated centrifugal separation and ultrasonic dispersion operations to obtain the nano thermally conductive filler.

9. The coolant according to claim 8, wherein The silane coupling agent is one or more of γ-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane.

10. The coolant according to claim 1, wherein The coolant further comprises one or more of a co-solvent, a coupling agent, an antioxidant, a dispersant, a flame retardant, and a defoaming agent.

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