Two-phase immersion cooling system

Abstract

An immersion cooling system includes a fluid holding vessel having a space for housing electronic devices. A heat transfer fluid is positioned in the vessel in contact with the electronic devices. A heat exchanger contacts and condenses vapor from vaporization of the heat transfer fluid. The heat transfer fluid has a thermal conductivity greater than 0.08 W m ‑1 K ‑1 , a dielectric constant (D k ) less than 3.0 at 20-40 GHz, and a heat of vaporization greater than 150 kJ kg ‑1 with flame retardant properties, material compatibility with plastics, metals, rubbers, and includes partially fluorinated compounds. The improved immersion cooling system includes a fluid with increased thermal conductivity and heat of vaporization while reducing the fluid density and maintaining the advantages of the fluid being non-flammable, having high electrical stability, and low dielectric constant.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Patent Application No. 63 / 322,647, filed March 23, 2022, and U.S. Patent Application No. 18 / 187,712, filed March 22, 2023, the disclosures of which are incorporated herein by reference. Technical Field

[0003] This invention relates to an immersion cooling system. More specifically, this invention relates to a two-phase immersion cooling system employing a novel coolant, which exhibits good thermal conductivity, high heat of vaporization, and low high-frequency dielectric constant. Background Technology

[0004] Currently, data centers have an ever-increasing demand for data processing and storage capabilities, with numerous heat-generating electronic devices placed close together. These high-power electrical systems generate a significant amount of heat, making it impossible for traditional air-based cooling systems (fans, air conditioning) to maintain satisfactory operating temperatures.

[0005] Immersion cooling is a recently developed direct cooling technology in which heat is removed by bringing a dielectric liquid into direct contact with the heat-generating components placed in a cooling tank. The dielectric liquid is cooled by one or more heat exchangers. Immersion cooling methods include single-phase and two-phase approaches. In single-phase immersion cooling, the dielectric liquid circulates between the heat-generating components, and the heated dielectric liquid is cooled by a heat exchanger; no phase change occurs during this process. In two-phase immersion cooling, the dielectric liquid comes into direct contact with the heat-generating components with excess heat, resulting in a vapor phase change. The vaporized dielectric liquid condenses through a heat exchanger and returns to the immersion cooling tank.

[0006] The heat transfer medium should be non-flammable and have no flash point, which is crucial for safety and long-term use. Furthermore, the fluid should be chemically and electrically stable, inert, and compatible with materials commonly used in electronic components. Typically, perfluorinated or partially fluorinated compounds can meet these requirements. However, the development of materials for two-phase systems is currently very limited. Existing commercial material systems for two-phase immersion cooling are manufactured by 3M. 1230 / 649 is an engineering fluid. Its characteristics include no flash point, high dielectric strength, low dielectric constant, and high reliability. However, its disadvantages include high density, low boiling point, low heat of vaporization, low thermal conductivity, and relatively high cost and complex manufacturing process for large-scale production.

[0007] Therefore, there is a need in the art for an improved immersion cooling system that includes a fluid with increased thermal conductivity and heat of vaporization, while reducing fluid density and maintaining its non-flammability, and possessing the advantages of high electrical stability and low dielectric constant. This invention addresses this need for improved immersion cooling. Summary of the Invention

[0008] This invention provides an immersion cooling system comprising a fluid holding container having space for housing electronic equipment. A heat transfer fluid is positioned within the container such that the electronic equipment is in contact with the heat transfer fluid. A heat exchanger is connected to the fluid holding container such that vaporized steam from the heat transfer fluid contacts the heat exchanger. The heat transfer fluid has a thermal conductivity greater than 0.08 W / m². -1 K -1 Dielectric constant (D) at 20-40 GHz k <3.0 and heat of vaporization >150 kJ / kg -1 The heat transfer fluid includes compounds of formula (I).

[0009]

[0010] X1, X2, and X3 are independently selected from hydrogen, deuterium, halogens, -CH3, -CF3, -CHF2, -CH2F, -OCH3, -OCF3, -OCH2CH3, -OCH2CF3, -OCF2CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, -CF2CF2CF3, -OCH2CF2CF3, and -CH2CH2CF3. R1 is selected from hydrogen, deuterium, halogens, C1-C10 alkyl, C3-C8 cycloalkyl, C2-C6 alkenyl, C3-C6 cycloalkenyl, C5-C7 (hetero)alkyl, and C2-C6 alkyl ethers having or being substituted with one or more fluorine atoms. The elemental weight percentage of fluorine atoms is less than 65%.

[0011] On the other hand, at least one of X1, X2 and X3 is selected from hydrogen or deuterium, and at least one of X1, X2 and X3 is selected from -CF3.

[0012] On the other hand, R1 is selected from C1-C10 straight-chain or branched alkyl groups having or being substituted with one or more fluorine atoms.

[0013] On the other hand, R1 is selected from -CH3, -CF3, -CH2CH3 or -CH2CF3.

[0014] On the other hand, the total number of fluorinated carbons in formula (I) is less than or equal to 3.

[0015] On the other hand, the boiling point of the heat transfer fluid ranges from 50°C to 100°C.

[0016] On the other hand, the heat transfer fluid is non-flammable and has no flash point.

[0017] On the other hand, the density of the heat transfer fluid is less than 1450 kg m³. -3 .

[0018] On the other hand, heat transfer fluids also include those with a density of less than 1200 kg m³. -3 The density reducing agent has a content of less than or equal to 50% by weight.

[0019] On the other hand, the density reducing agent is selected from diethyl ether, petroleum ether, tetrahydrofuran, hexane, heptane, octane, cyclohexane, diethylene glycol, 2-butanone, ethyl acetate, ethyl propionate, methyl propionate, hexane, heptane, octene, or dimethyl carbonate.

[0020] On the other hand, the heat transfer fluid also includes a flame retardant, the content of which is less than or equal to 50% by weight.

[0021] On the other hand, the flame retardant is selected from 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,2,2-pentafluoroethane, bromochlorodifluoromethane, trifluorobromomethane, perfluoro(2-methyl-3-pentanone), perfluoro(2,4-dimethyl-3-pentanone), heptafluoro-1-methoxypropane, methyl nonafluoroisobutyl ether, ethyl nonafluoroisobutyl ether, 3-methoxyperfluoro(2-methylbutane), 1,1,1,2,2,3,4,5,5-difluoro-3-methoxy-4-(trifluoromethyl)pentane, perfluoro(4-methyl-2-pentene), trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, trimethylbenzene phosphate, or tri(1-chloro-2-propyl) phosphate.

[0022] On the other hand, the heat transfer fluid includes 25 to 80% by weight of the compound of formula (I) based on the total weight of the heat transfer fluid.

[0023] On the other hand, the heat transfer fluid includes 50 to 70% by weight of the compound of formula (I) based on the total weight of the heat transfer fluid.

[0024] Compound (I) is compatible with plastics, metals and rubbers of electronic components cooled by immersion cooling systems.

[0025] The plastic can be one or more of epoxy resin, ABS resin, PP, PE, PC, PTFE, or FR-4.

[0026] The metal can be one or more of the following: copper, navy brass, cupronickel, 304 stainless steel, 316 stainless steel, 6061 aluminum alloy, H68 brass, H62 brass, H59 brass, L245 alloy, lead-tin alloy, or tin-copper alloy.

[0027] The rubber can be one or more of silicone rubber, nitrile rubber, fluororubber, chloroprene rubber, EPDM, hydrogenated nitrile rubber, or polyurethane-based rubber.

[0028] When flame retardants are used, coolant vapors can extinguish the fire within 5 seconds. Attached Figure Description

[0029] Figure 1 This diagram shows an immersion cooling system according to one embodiment. Detailed Implementation

[0030] For two-phase immersion cooling, a major factor affecting heat exchange efficiency is the heat of vaporization of the heat transfer fluid, which is the amount of energy the fluid must absorb to convert into a gas. The higher the heat of vaporization, the more heat the fluid absorbs for phase change. Therefore, this invention partially provides an improved immersion cooling system in which the heat transfer fluid has a higher heat of vaporization than existing immersion cooling systems. Figure 1 A two-phase immersion cooling system 100 according to one embodiment is depicted. The immersion cooling system 100 includes a fluid holding container 110 having space for housing electronic equipment 130. Typically, in a data center environment, the electronic equipment 130 may be a server or a server component.

[0031] Heat transfer fluid 120 is positioned in container 110 such that electronic equipment 130 is in contact with heat transfer fluid 120. Heat exchanger 140 is connected to fluid holding container 110 such that vapor 125 from heat transfer fluid 120 contacts heat exchanger 140. Heat exchanger is maintained at a temperature below the boiling point of heat transfer fluid. Upon contact with heat exchanger 140, vapor 125 condenses and returns to the storage container of heat transfer fluid 120. The heat released during condensation is transferred to heat exchanger.

[0032] Although Figure 1 Not shown above, the submerged cooling system 100 may also include pumps for circulating the heat exchange fluid and pumps for circulating the coolant within the heat exchanger. The heat exchanger can have a variety of different surfaces and configurations, depending on the size of the submerged cooling system 100 and the volume of vapor condensed by the heat exchanger. For example, the heat exchanger may include fins, plates, coils, and other known heat exchanger surfaces. Typically, water is used as the coolant within the heat exchanger; cold air and other known refrigerants may also be used.

[0033] Heat of vaporization (ΔH) vap Latent heat, also known as heat of vaporization, is the energy (enthalpy) that must be added to a liquid substance to convert a certain amount of the liquid substance into a gas. It is an important parameter of two-phase immersion cooling systems. Heat transfer fluids with high heat of vaporization can remove more heat from the system. In some embodiments, according to the disclosed ASTM E2071 test method "Standard Implementation Procedure for Calculating Heat of Vaporization or Heat of Sublimation from Vapor Pressure Data", the heat transfer fluid of the present invention has a heat of vaporization greater than 150 kJ / kg. -1 .

[0034] Thermal conductivity is a measure of a material's ability to conduct heat. In two-phase immersion cooling systems, the rate of heat transfer from the heated components to the contacting engineered heat transfer fluid is crucial. In some embodiments, the heat transfer fluid 120 of the present invention has a thermal conductivity greater than 0.08 W / m³, according to the disclosed ASTM D7896 test method, "Standard Test Method for Determining the Thermal Conductivity, Thermal Diffusivity and Volumetric Heat Capacity of Engine Coolants and Related Fluids by Transient Hot-Wire Liquid Thermal Conductivity Method". -1 K -1 Thermal conductivity.

[0035] Dielectric constant (D) k Permeability (D) is the dielectric constant of a material, expressed as the ratio of the dielectric constant of vacuum to that of air. It measures a material's ability to store electrical energy in an electric field. When electronic components are immersed in a low-D... k When the material is in a suitable state, signal loss is minimal. In some embodiments, the dielectric flux D at frequencies from 10 MHz to 50 GHz is measured using the N1601A dielectric probe kit. k Value. The dielectric constant (Dt) of the heat transfer fluid 120 disclosed herein at 20 to 40 GHz. k (less than 3.0)

[0036] The heat transfer fluid includes compounds of formula (I):

[0037]

[0038] X1, X2, and X3 are independently selected from hydrogen, deuterium, halogen, -CH3, -CF3, -CHF2, -CH2F, -OCH3, -OCF3, -OCH2CH3, -OCH2CF3, -OCF2CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, -CF2CF2CF3, -OCH2CF2CF3, and -CH2CH2CF3.

[0039] In one embodiment, at least one of X1, X2, and X3 is selected from hydrogen or deuterium, and at least one of X1, X2, and X3 is selected from -CF3.

[0040] R1 is selected from hydrogen, deuterium, halogen, C1-C10 alkyl, C3-C8 cycloalkyl, C2-C6 alkenyl, C3-C6 cycloalkenyl, C5-C7 heteroalkyl, and C2-C6 alkyl ethers having or being substituted with one or more fluorine atoms. In one embodiment, R1 may be a C1-C10 straight-chain or branched alkyl having or being substituted with one or more fluorine atoms; examples of R1 include -CH3, -CF3, -CH2CH3, or -CH2CF3.

[0041] In one embodiment, R1 in formula (I) may be selected from hydrogen, deuterium, and the group consisting of: (1) halogen, which may be selected from the group consisting of fluorine, chlorine, bromine and iodine atoms; (2) C1-C10 alkyl, which may further be selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, trifluoromethyl, pentafluoromethyl, 2,2,2-trifluoroethyl; (3) C3-C8 cycloalkyl, which may further be selected from The following groups: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl; (4) C2-C6 alkenyl, which may further be selected from the following groups: vinyl, propenyl, butenyl, pentenyl, hexenyl; (5) C3-C6 cycloalkenyl, which may further be selected from the following groups: cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl; (6) C2-C6 alkyl ether group, which may further be selected from the following groups: methoxy, ethoxy, n-propoxy, isopropoxy, n-butanol, isobutanol or sec-butanol, tert-butanol or 2-methylbutanol.

[0042] In one embodiment, the compound described in formula (I) is a partially fluorinated compound having a fluorine atom weight percentage of less than 65%.

[0043] In one embodiment, the total number of fluorinated carbons in formula (I) is less than or equal to 3.

[0044] In one embodiment, the weight percentage of fluorine atoms in formula (I) is less than 60%.

[0045] As used herein, the term "heterogeneous" refers to non-carbon atoms (e.g., oxygen, nitrogen, or sulfur) linked to a carbon chain (straight chain, branched chain, or ring).

[0046] As used herein, unless the context otherwise requires, the term "or" includes "and / or".

[0047] In this invention, "replaced by one or more fluorine atoms" means that one or more hydrogen atoms on the carbon atom of the substituent are replaced by fluorine atoms.

[0048] The following provides specific, but not limited to, suitable examples of heat transfer fluids according to the present invention:

[0049]

[0050] Heat transfer fluids with higher boiling points can be used for heat-generating components with higher operating temperatures. The development of computer chips, 5G technology, and the ever-increasing data processing power with the increasing number of servers and printed circuit boards in data centers also generate higher heat. Therefore, the heat transfer fluid of this invention is engineered to have a higher boiling point than conventional heat transfer fluids. The boiling point of the heat transfer fluid is tested according to ASTM D1120-08, "Standard Test Method for Boiling Point of Engine Coolants." In some embodiments, the boiling point of heat transfer fluid 120 ranges from 50°C to 100°C. In some embodiments, the boiling point of the heat transfer fluid 120 of this disclosure may be between 50 and 100°C, or between 60 and 90°C, or between 65 and 80°C.

[0051] In some embodiments, the fluorinated heat transfer fluid 120 of the present invention is non-flammable and has no flash point, according to the disclosed ASTM D3828-16a(2021) test method "Standard Test Method for Determining Flash Point Using a Small Closed Cup Tester".

[0052] In addition to having a higher boiling point, it is desirable to reduce the density of the heat transfer fluid. Lower density fluids require less fuel to transport a given weight of heat transfer fluid and require less energy for pumping and circulating in data center environments. The test method for heat transfer fluid density is according to ASTM D1298-12b (2017), "Standard Test Method for Determination of Density, Relative Density, or API Specific Gravity of Crude Oils and Liquid Petroleum Products by Hydrometer Method". In some embodiments, the density of heat transfer fluid 120 is less than 1450 kg m³. -3 This lower density heat transfer fluid can be used with a density of less than 1200 kg m³. -3 This is achieved using a density-reducing agent, the content of which is less than or equal to 50% of the weight of the heat transfer fluid. Examples of density-reducing agents include diethyl ether, petroleum ether, tetrahydrofuran, hexane, heptane, octane, cyclohexane, diethylene glycol, 2-butanone, ethyl acetate, ethyl propionate, methyl propionate, hexane, heptane, octene, or dimethyl carbonate.

[0053] Due to the nature of the data center environment, flame retardants may be required, with a content less than or equal to 50% by weight of the heat transfer fluid. Flame retardants may be one or more of the following: 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,2,2-pentafluoroethane, bromochlorodifluoromethane, trifluorobromomethane, perfluoro(2-methyl-3-pentanone), perfluoro(2,4-dimethyl-3-pentanone), heptafluoro-1-methoxypropane, methyl nonafluoroisobutyl ether, ethyl nonafluoroisobutyl ether, 3-methoxyperfluoro(2-methylbutane), 1,1,1,2,2,3,4,5,5-difluoro-3-methoxy-4-(trifluoromethyl)pentane, perfluoro(4-methyl-2-pentene), trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, trimethylbenzene phosphate, or tri(1-chloro-2-propyl) phosphate. Using flame retardants can extinguish the fire within 5 seconds.

[0054] Taking into account density-reducing additives and flame-retardant additives, the heat transfer fluid may include a compound of formula (I) at a weight percentage of 1 to 100% based on the total weight of the heat transfer fluid. In particular, the compound of formula (I) may be 25 to 80 wt% based on the total weight of the heat transfer fluid, or more specifically, 50 to 70% based on the total weight of the heat transfer fluid.

[0055] In one embodiment, the heat transfer fluid of the present invention is a liquid.

[0056] In another embodiment, the heat transfer fluid of the present invention is a suspension.

[0057] In another embodiment, the heat transfer fluid of the present invention is a nanofluid, wherein the heat transfer fluid is mixed with nanoparticles including carbon nanoparticles, multi-walled carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs), graphene, graphene oxide, graphite, fullerene, diamond, silver nanoparticles, gold nanoparticles, copper nanoparticles, aluminum nanoparticles, iron nanoparticles, nickel nanoparticles, zinc nanoparticles, alumina (Al2O3) nanoparticles, titanium dioxide (TiO2) nanoparticles, silicon nanoparticles, silicon carbide nanoparticles, boron nitride nanoparticles, silicon dioxide nanoparticles, or aluminum nitride nanoparticles.

[0058] Importantly, the cooling system and coolant of the present invention are compatible with the plastics, metals, and rubbers used in the motherboards of electronic components cooled by the system. That is, the coolant will not react with or degrade these materials in any way. For example, the coolant is compatible with plastics (including epoxy resins, ABS resins, PP, PE, PC, PTFE, and FR-4) and other plastics / polymers used in electronic components.

[0059] The coolant is compatible with metals used in electronic devices, such as copper, navy brass, cupronickel, 304 stainless steel, 316 stainless steel, 6061 aluminum alloy, H68 brass, H62 brass, H59 brass, L245 alloy, lead-tin alloy, or tin-copper alloy. Furthermore, the coolant will not react with or degrade dopants in semiconductor materials (such as silicon, GaAs, GaN, and indium-based semiconductors) or semiconductor devices.

[0060] The immersion cooling system coolant is also compatible with rubber / sealants used in semiconductor device packaging and housings containing electronic components such as servers. The coolant is compatible with silicone rubber, nitrile rubber, fluororubber, neoprene rubber, EPDM, hydrogenated nitrile rubber, and polyurethane-based rubber.

[0061] The heat transfer fluid used in the immersion cooling system of this invention can be manufactured using relatively inexpensive manufacturing techniques, wherein precursor materials are mixed and reacted at relatively low temperatures. Furthermore, this production method is environmentally friendly, as it does not use toxic or hazardous chemicals. Since organic solvents are hazardous substances requiring special handling and disposal procedures, only water and water-soluble chemicals are used in the production method of the heat transfer fluid in this disclosure. The heat transfer fluid is readily separated from the reaction products and can be easily purified using conventional distillation techniques.

[0062] Example

[0063] A two-phase immersion cooling system includes a fluid holding container having space for housing electronic equipment, a heat transfer fluid positioned in the container such that the electronic equipment is in contact with the heat transfer fluid, and a heat exchanger in communication with the fluid holding container such that vaporized steam from the heat transfer fluid contacts the heat exchanger. The heat transfer fluid used was 1,1,1,3,3,3-hexafluoropropane-2-yl acetate (Example 1) or 2,2,2-trifluoroethyl 3,3,3-trifluoropropionate containing 15% by weight of dimethyl carbonate and 75% by weight as a density reducing agent, and 10% by weight of perfluorinated (4-methyl-2-pentene) as a flame retardant (Example 2) or 2,2,2-trifluoro-1-methoxyethyl acetate containing 20% ​​by weight of trimethyl phosphate and 80% by weight as a flame retardant (Example 3) or NOVEC 649 engineering fluid (Comparative Example 1) or NOVEC 7000 engineering fluid (Comparative Example 2) or NOVEC 7100 engineering fluid (Comparative Example 3).

[0064] Preparation of Example 1

[0065] Synthesis of 1,1,1,3,3,3-hexafluoropropane-2-yl acetate

[0066]

[0067] 200 g (1 equivalent) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC.HCl, CAS: 25952-53-8) and 4-dimethylaminopyridine (DMAP, CAS: 1122-58-3) (38.3 g, 0.3 equivalent) were mixed in a 1000 mL round-bottom flask, and deionized water (500 mL) was added to dissolve the solids. Then, glacial acetic acid (CAS: 64-19-7) (75.4 g, 1.2 equivalent) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, CAS: 920-66-1) (184.7 g, 1.05 equivalent) were slowly added to the EDC.HCl and DMAP mixture to avoid temperature rise. The reaction mixture was stirred and heated to 40 °C for 24 hours. The reaction was then allowed to stabilize, and two layers separated. The upper aqueous layer was removed, and then the bottom organic layer was distilled. The fraction with a boiling point of approximately 70°C was collected. Yield: 132 g (60%). The product was confirmed by NMR analysis. 1 H NMR [500MHz, CDCl3]: δ 2.25 (s, 3H), 5.71–5.78 (septet, 1H) and 19 F NMR [500MHz, CDCl3]: δ73.62 (s, 6F).

[0068] Preparation of Example 2

[0069] Synthesis of 2,2,2-trifluoroethyl 3,3,3-trifluoropropionate

[0070]

[0071] EDC.HCl (200 g, 1 equivalent) and DMAP (38.3 g, 0.3 equivalent) were mixed in a 1000 mL round-bottom flask and deionized water (500 mL) was added to dissolve the solid. Then, 3,3,3-trifluoropropionic acid (CAS: 2516-99-6) (147.5 g, 1.1 equivalent) and 2,2,2-trifluoroethanol (TFE, CAS: 75-89-8) (110 g, 1.05 equivalent) were slowly added to the EDC.HCl and DMAP mixture to avoid temperature rise. The reaction mixture was stirred and heated to 40 °C for 24 hours. The reaction was then allowed to stabilize, and two layers were separated. The upper aqueous layer was removed, and the bottom organic layer was distilled. The fraction with a boiling point below 80 °C was collected. Yield: 125.4 g (57%). The product was confirmed by NMR analysis. 1 H NMR [500MHz, CDCl3]: δ 2.77 (q, 2H), 4.60 (q, 2H) and 19F NMR [500MHz, CDCl3]: δ74.86(s,3F), δ92.27(s,3F).

[0072] Example 2 contains 15% by weight of dimethyl carbonate, 75% by weight of 2,2,2-trifluoroethyl 3,3,3-trifluoropropionate as a density reducer, and 10% by weight of perfluorinated (4-methylpent-2-ene) as a flame retardant.

[0073] Preparation of Example 3

[0074] Synthesis of ethyl 2,2,2-trifluoro-1-methoxyethyl

[0075]

[0076] EDC.HCl (200 g, 1 equivalent) and DMAP (38.3 g, 0.3 equivalent) were mixed in a 1000 mL round-bottom flask and deionized water (500 mL) was added to dissolve the solids. Then, glacial acetic acid (CAS: 64-19-7) (75.4 g, 1.2 equivalent) and trifluoroacetaldehyde methyl hemiacetal (CAS: 431-46-9) (142.5 g, 1.05 equivalent) were slowly added to the EDC.HCl and DMAP mixture to avoid temperature rise. The reaction mixture was stirred and heated to 40 °C for 24 hours. The reaction was then allowed to stabilize, and two layers were separated. The upper aqueous layer was removed, and the bottom organic layer was distilled. The fraction with a boiling point below 80 °C was collected. Yield: 73.6 g (41%). The product was confirmed by NMR analysis. 1 H NMR [500MHz, CDCl3]: δ2.03 (s, 3H), δ3.40 (s, 3H), 7.28 (q, 1H) and 19 F NMR [500MHz, CDCl3]: δ77.11 (s, 3F).

[0077] Example 3 uses 20% by weight of trimethyl phosphate and 80% by weight of ethyl 2,2,2-trifluoro-1-methoxyacetate as a flame retardant.

[0078] The chemical structures of density reducers and flame retardants are shown below:

[0079]

[0080] For the commercially available engineering fluids, comparative examples CE1, CE2 and CE3 were purchased from 3M and used directly without further treatment.

[0081] Table 1 shows the characteristics of the example heat transfer fluids used and a comparison with commercial fluids:

[0082]

[0083]

[0084] As shown in Table 1, the heat transfer fluid of the present invention provides a relatively low fluorine atomic weight percentage compared to commercially available products. While the fluid of the present invention achieves a suitable boiling point range, it exhibits no flash point, high dielectric strength, low dielectric constant, and high heat of vaporization and thermal conductivity. Furthermore, compared to prior art materials, the heat transfer fluid of the present invention has significantly higher boiling points, higher dielectric strength, higher heat of vaporization, and significantly higher thermal conductivity. Since the heat of vaporization is directly related to the efficiency of the heat transfer process in a two-phase immersion cooling system, this system has higher heat transfer capabilities. Moreover, to compare partially fluorinated compounds, the heat transfer fluid of the present invention has lower dielectric constant values ​​than commercial products CE2 and CE3 at low frequencies (1 kHz), high frequencies (20 GHz), and very high frequencies (40 GHz).

[0085] For ease of description, this document uses spatially related terms such as "under," "below," "lower part," "above," "upper portion," "lower portion," "left side," and "right side" to describe the relationship between one element or feature and another element or feature as shown in the figure. In addition to the orientation shown in the figure, spatially related terms are intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatially related descriptors used herein may also be used for the corresponding interpretation. It should be understood that when one component is "connected" or "coupled" to another component, the component may be directly connected to or coupled to the other component, or there may be an intermediate component.

[0086] As used herein, the terms "about," "substantially," "truly," and "approximately" are used to describe and explain a small variation. When used in conjunction with an event or situation, the term can refer to the exact occurrence of the event or situation, or approximately the occurrence of the event or situation. As with any given value or range used herein, the term "approximately" typically refers to ±10%, ±5%, ±1%, or ±0.5% of a given value or range. A range may be indicated herein as from one endpoint to another or between two endpoints. Unless otherwise specified, all ranges disclosed in this disclosure include endpoints. The term "truly coplanar" can refer to two surfaces located within a few micrometers (μm) along the same plane, for example, within 10 μm, 5 μm, 1 μm, or 0.5 μm along the same plane. When referring to the same numerical value or characteristic, the term can refer to a value within ±10%, ±5%, ±1%, or ±0.5% of the average value.

[0087] The foregoing briefly describes several embodiments and detailed features of this disclosure. The embodiments described in this disclosure can be readily used as the basis for designing or modifying other processes and structures to achieve the same or similar objectives introduced in the embodiments of this disclosure and / or obtain the same or similar advantages. Such equivalent structures do not depart from the spirit and scope of this disclosure, and various changes, substitutions, and modifications can be made without departing from the spirit and scope of the invention.

Claims

1. An immersion cooling system, characterized in that, include: A fluid-holding container with space for accommodating electronic equipment; A heat transfer fluid is positioned in the fluid holding container such that the electronic device comes into contact with the heat transfer fluid; A heat exchanger that maintains communication with the fluid in a container, such that vapors from the heat transfer fluid, vaporized from the heat transfer fluid, come into contact with the heat exchanger; The heat transfer fluid has a strength greater than 0.08 W / m³. -1 K -1 Thermal conductivity and dielectric constant (D) at 20-40 GHz k <3.0, heat of vaporization >150 kJ / kg -1 And including compounds of formula (I) containing less than 65% fluorine atoms by weight: Formula (I), X1, X2, and X3 are independently selected from hydrogen, -CF3, and -OCH3; R1 is selected from C1-C10 alkyl groups, or C1-C10 straight-chain or branched alkyl groups substituted with one or more fluorine atoms.

2. The immersion cooling system according to claim 1, wherein at least one of X1, X2 and X3 is selected from hydrogen, at least one of X1, X2 and X3 is selected from -CF3, and R1 is selected from -CF3.

3. The immersion cooling system according to claim 1, wherein the total number of fluorine atoms in formula (I) is less than or equal to 3.

4. The immersion cooling system according to claim 1, wherein the boiling point of the heat transfer fluid is in the range of 50°C to 100°C.

5. The immersion cooling system according to claim 1, wherein the heat transfer fluid is non-flammable and has no flash point.

6. The immersion cooling system according to claim 1, wherein the density of the heat transfer fluid is less than 1450 kg m³. -3 .

7. The immersion cooling system according to claim 1, wherein the heat transfer fluid further comprises a density of less than 1200 kg / m³. -3 The density reducing agent has a content of less than or equal to 50% by weight.

8. The immersion cooling system according to claim 7, wherein the density reducing agent is selected from diethyl ether, petroleum ether, tetrahydrofuran, hexane, heptane, octane, cyclohexane, diethylene glycol, 2-butanone, ethyl acetate, ethyl propionate, methyl propionate, octene, or dimethyl carbonate.

9. The immersion cooling system according to claim 1, wherein the heat transfer fluid further comprises a flame retardant having a content of less than or equal to 50% by weight.

10. The immersion cooling system according to claim 9, wherein the flame retardant is selected from 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,2,2-pentafluoroethane, bromochlorodifluoromethane, trifluorobromomethane, perfluoro(2-methyl-3-pentanone), perfluoro(2,4-dimethyl-3-pentanone), heptafluoro-1-methoxypropane, methyl nonafluoroisobutyl ether, ethyl nonafluoroisobutyl ether, 3-methoxyperfluoro(2-methylbutane), 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane, perfluoro(4-methyl-2-pentene), trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, trimethylbenzene phosphate, or tri(1-chloro-2-propyl) phosphate.

11. The immersion cooling system of claim 1, wherein the heat transfer fluid comprises 25 to 80% by weight of a compound of formula (I) based on the total weight of the heat transfer fluid.

12. The immersion cooling system of claim 1, wherein the heat transfer fluid comprises 50 to 70% by weight of a compound of formula (I) based on the total weight of the heat transfer fluid.

13. The immersion cooling system of claim 1, wherein the compound of formula (I) is compatible with the plastics, metals and rubbers of the electronic components cooled by the immersion cooling system.

14. The immersion cooling system of claim 13, wherein the plastic is one or more of epoxy resin, ABS resin, PP, PE, PC, PTFE, or FR-4.

15. The immersion cooling system according to claim 13, wherein the metal is one or more of copper, navy brass, cupronickel, 304 stainless steel, 316 stainless steel, 6061 aluminum alloy, H68 brass, H62 brass, H59 brass, L245 alloy, lead-tin alloy, or tin-copper alloy.

16. The immersion cooling system according to claim 13, wherein the rubber is one or more of silicone rubber, nitrile rubber, fluororubber, neoprene rubber, EPDM, hydrogenated nitrile rubber, or polyurethane rubber.

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