A liquid cooling medium and its preparation method and application

Abstract

The present invention provides a liquid cooling medium and a preparation method and application thereof, belonging to the field of chemical industry. The liquid cooling medium prepared by the preparation method provided by the present invention is a hydrofluoroolefin mixture, comprising two material components, CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3. The mixture is spontaneously generated in the preparation process, and there is no need to separate the two, and it can be directly used as a two-phase immersion liquid cooling medium. The preparation method of the present invention is of great significance for preparing candidate working fluids with excellent performance and stable quality for immersion cooling systems, optimizes the synthesis process of hydrofluoroolefins, and provides a full-process preparation process method for raw materials, intermediates and final products. The final product obtained has stable quality and excellent performance. The prepared liquid cooling medium has the advantages of efficient heat dissipation and temperature control, which can achieve the purpose of energy saving and consumption reduction.

Description

Technical Field

[0001] The present invention relates to the field of chemical technology, and in particular to a liquid cooling medium and a preparation method and application thereof. Background Art

[0002] Hydrofluoroolefins (HFOs) f -CH=CH-R' f ) has an ODP of zero and a low GWP, which is environmentally friendly. Compared with perfluoroolefins, hydrofluoroolefins have better structural stability, and the carbon-carbon double bond is not easily displaced or acidified. f -CH=CH-R f 'Having low dielectric properties, it holds promise for immersion cooling applications in electronics.

[0003]

[0004] The molecular formula is C6H2F 10 Three non-terminal hydrofluoroolefins (E)-1,1,1,4,5,5,5-heptafluoro-4-trifluoromethyl-2-pentene (HFO-153-10mzzy), (E)-1,1,1,4,4,5,5,6,6,6-decafluoro-2-hexene (HFO-153-10mzz), and (E)-1,1,1,2,2,5,5,6,6,6-decafluoro-3-hexene (HFO-153-10mczz) have a boiling point of about 50°C (normal pressure) and a relative dielectric constant of about 2.0, and may be candidate working fluids for the gas-liquid two-phase immersion cooling (2PIC) system.

[0005] In the prior art, patents WO2018224908A1 and CN110709373A disclose an immersion cooling fluid system including HFO-153-10mzzy; patents US2023112841A1 and WO2023064123A1 disclose an immersion cooling system using low GWP fluids HFO-153-10mczz (E-F22E) and HFO-153-10mzzy (E-F13iE); patents WO2007059468, US2007152200A1, US 2012175137A1, US8148584B2 and US9119982B2 disclose fire extinguishing and fire suppressing components composed of unsaturated fluorocarbons, wherein HFO-153-10mzzy is prepared by a two-step reaction: the first step is the addition of free radicals to carbon-carbon double bonds by thermal initiation at 180°C between heptafluoroisopropyl iodide and 3,3,3-trifluoropropylene (1:1) to obtain a system containing 10-12% of raw materials, 62% of monoaddition products, and 12% of diaddition byproducts; the second step is the reaction of the intermediate with potassium hydroxide at 75-10°C under phase transfer catalysis conditions. The elimination reaction is carried out at 0°C, and the product has a yield of 81%; Patents US2007096051A1, US2007100010A1 and US2007098646A1 disclose fire extinguishing and fire suppressing components composed of unsaturated fluorocarbons, foam forming foaming agents composed of unsaturated fluorocarbons, and aerosol propellants composed of unsaturated fluorocarbons, including unsaturated fluorocarbons such as HFO-153-10mzzy (F13iE), HFO-153-10mczz (F13E) and HFO-153-10mzz (F22E). F13iE is prepared by a two-step reaction similar to the aforementioned thermal addition and alkali elimination: the first step is a 200°C thermally initiated addition of heptafluoroisopropyl iodide and 3,3,3-trifluoropropylene (2:1), and a 62% yield of the intermediate is obtained by reduced pressure distillation; the second step is an elimination reaction of the intermediate with potassium hydroxide at 42-62°C, and the product is distilled off at normal pressure, and the product is 55% yield; the electronic component immersion cooling fluid system disclosed in patents WO2022096995A1 and CN116472635A, the synthesis of HFO-153-10mzzy is carried out with reference to US8148584B2, the first step is an addition initiated by dibenzoyl peroxide, and the intermediate product of the 115°C fraction is purified, and the second step is an elimination reaction of the intermediate with potassium hydroxide, and the target product is obtained by steam distillation.

[0006] None of the above preparation processes discloses the synthesis process of HFO-153-10mzz, but only discloses a method for preparing HFO-153-10mzzy using the raw material heptafluoroisopropyl iodide. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a liquid cooling medium and its preparation method and application. The present invention provides a new preparation method of a hydrofluoroolefin mixture for immersion liquid cooling medium, which can be directly used as a two-phase liquid cooling medium, and optimizes the synthesis process of hydrofluoroolefins.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing a liquid cooling medium, comprising the following steps:

[0010] Electrofluorinating an n-butyl compound in anhydrous hydrogen fluoride to obtain a mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride, and absorbing the mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride with an alkali solution to obtain a mixture of perfluorobutyrate and perfluoroisobutyrate;

[0011] The mixture of perfluorobutyrate and perfluoroisobutyrate is subjected to a thermal decomposition reaction with iodine in an anhydrous aprotic solvent to obtain a mixture of perfluoropropyl iodide and perfluoroisopropyl iodide;

[0012] The mixture of perfluoropropyl iodide and perfluoroisopropyl iodide is subjected to a free radical addition reaction with 3,3,3-trifluoropropylene to obtain an intermediate reaction liquid, wherein the intermediate reaction liquid includes CF3CF2CF2CHICH2CF3 and (CF3)2-CFCHICHCF3;

[0013] The intermediate reaction liquid is treated with an alkali-alcohol mixed liquid to eliminate HI, thereby obtaining the liquid cooling medium.

[0014] Preferably, the n-butyl compound includes one or more of n-butyryl chloride, n-butyryl fluoride and n-butyric acid.

[0015] Preferably, the molar ratio of the n-butyl compound to anhydrous hydrogen fluoride is 1:8-16.

[0016] Preferably, the temperature of the electrolytic fluorination is -10 to 10°C.

[0017] Preferably, the molar ratio of the mixture of perfluorobutyrate and perfluoroisobutyrate to elemental iodine is 1:1 to 1.5.

[0018] Preferably, the temperature of the thermal decomposition reaction is 180-240° C., and the time is 4-8 hours.

[0019] Preferably, in the mixture of perfluoropropyl iodide and perfluoroisopropyl iodide, the mass percentage of perfluoropropyl iodide is 80-98%, and the mass percentage of perfluoroisopropyl iodide is 2-20%.

[0020] The present invention also provides a liquid cooling medium obtained by the above preparation method, including CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3.

[0021] Preferably, the mass percentage of CF3CF2CF2CH=CHCF3 in the liquid cooling medium is 83-98.5%, and the mass percentage of (CF3)2CFCH=CHCF3 is 1.5-17%.

[0022] The present invention also provides the use of the liquid cooling medium described in the above technical solution as a two-phase immersion liquid cooling medium.

[0023] The invention provides a method for preparing a liquid cooling medium, comprising the following steps: subjecting an n-butyl compound to electrofluorination in anhydrous hydrogen fluoride to obtain a mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride, absorbing the mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride by alkali solution to obtain a mixture of perfluorobutyrate and perfluoroisobutyrate; subjecting the mixture of perfluorobutyrate and perfluoroisobutyrate to thermal decomposition reaction with iodine element in an anhydrous aprotic solvent to obtain a mixture of perfluoropropyl iodine and perfluoroisopropyl iodine; subjecting the mixture of perfluoropropyl iodine and perfluoroisopropyl iodine to free radical addition reaction with 3,3,3-trifluoropropylene to obtain an intermediate reaction liquid, wherein the intermediate reaction liquid comprises CF3CF2CF2CHICH2CF3 and (CF3)2-CFCHICHCF3; and subjecting the intermediate reaction liquid to alkali-alcohol mixed solution treatment to eliminate HI to obtain the liquid cooling medium.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The liquid cooling medium prepared by the preparation method provided by the present invention is a mixture of hydrofluoroolefins, which contains two material components, CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3. The mixture is spontaneously generated in the preparation process, and there is no need to separate the two, and it can be directly used as a two-phase immersion liquid cooling medium. The preparation process method of the present invention is of great significance for preparing candidate working fluids with excellent performance and stable quality for immersion cooling systems, optimizes the synthesis process of hydrofluoroolefins, and provides a full-process preparation process method for raw materials, intermediates and final products. The final product obtained has stable quality and excellent performance. The prepared liquid cooling medium has the advantages of efficient heat dissipation and temperature control, which can achieve the purpose of energy saving and consumption reduction. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing a liquid cooling medium, comprising the following steps:

[0027] Electrofluorinating an n-butyl compound in anhydrous hydrogen fluoride to obtain a mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride, and absorbing the mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride with an alkali solution to obtain a mixture of perfluorobutyrate and perfluoroisobutyrate;

[0028] The mixture of perfluorobutyrate and perfluoroisobutyrate is subjected to a thermal decomposition reaction with iodine in an anhydrous aprotic solvent to obtain a mixture of perfluoropropyl iodide and perfluoroisopropyl iodide;

[0029] The mixture of perfluoropropyl iodide and perfluoroisopropyl iodide is subjected to a free radical addition reaction with 3,3,3-trifluoropropylene to obtain an intermediate reaction liquid, wherein the intermediate reaction liquid includes CF3CF2CF2CHICH2CF3 and (CF3)2-CFCHICHCF3;

[0030] The intermediate reaction liquid is treated with an alkali-alcohol mixed liquid to eliminate HI, thereby obtaining the liquid cooling medium.

[0031] In the present invention, unless otherwise specified, the raw materials used are all commercially available products in the art.

[0032] The invention electrolytically fluorinates an n-butyl compound in anhydrous hydrogen fluoride to obtain a mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride, and absorbs the mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride through an alkali solution to obtain a mixture of perfluorobutyrate and perfluoroisobutyrate.

[0033] In the present invention, the n-butyl compound preferably includes one or more of n-butyryl chloride, n-butyryl fluoride and n-butyric acid.

[0034] In the present invention, taking the n-butyl compound as n-butyryl chloride or n-butyryl fluoride as an example, the principle of preparing the mixture of perfluorobutyrate and perfluoroisobutyrate is as shown in the following formula:

[0035]

[0036] In the present invention, the temperature of the electrolytic fluorination is preferably -10 to 10°C, more preferably -10°C, 0°C or 10°C.

[0037] In the present invention, the molar ratio of the n-butyl compound to anhydrous hydrogen fluoride is preferably 1:8-16, more preferably 1:8, 1:12 or 1:16.

[0038] In the present invention, during the electrolytic fluorination process, it is preferred to observe the electrolysis conditions and continuously add a mixed solution having a molar ratio of n-butyl compound to anhydrous hydrogen fluoride of ≤1 / 10.

[0039] In the present invention, the alkali solution is preferably a KOH solution or a NaOH solution, and the mass concentration of the alkali solution is preferably 30-50%, more preferably 30%, 40% or 50%. When the alkali solution is a KOH solution, a mixture of perfluorobutyric acid potassium salt and perfluoroisobutyric acid potassium salt is obtained, and when the alkali solution is a NaOH solution, a mixture of perfluorobutyric acid sodium salt and perfluoroisobutyric acid sodium salt is obtained.

[0040] In the present invention, the temperature of the alkali solution is preferably <20°C.

[0041] In the present invention, the absorption temperature is preferably <20°C, more preferably 15°C.

[0042] In the present invention, after the absorption is completed, the absorbed solution is preferably dried by a spray drying process to obtain white powder crystals, which are the perfluorobutyrate and perfluoroisobutyrate or a mixture thereof.

[0043] In the present invention, the temperature of the spray drying process is preferably 120°C.

[0044] In the present invention, the moisture content of the white powder crystals is preferably less than 100 ppm.

[0045] In the present invention, the white powder crystals preferably contain potassium fluoride / sodium salt or potassium chloride / sodium salt in addition to the mixture of perfluorobutyrate and perfluoroisobutyrate. The potassium fluoride / sodium salt or potassium chloride / sodium salt has no effect on the subsequent preparation process and does not require separation and removal operations.

[0046] After obtaining the mixture of perfluorobutyrate and perfluoroisobutyrate, the present invention conducts a thermal decomposition reaction between the mixture of perfluorobutyrate and perfluoroisobutyrate and elemental iodine in an anhydrous aprotic solvent to obtain a mixture of perfluoropropyl iodide and perfluoroisopropyl iodide.

[0047] In the present invention, the principle of the thermal decomposition reaction is shown in the following formula:

[0048]

[0049] In the present invention, the molar ratio of the mixture of perfluorobutyrate and perfluoroisobutyrate to elemental iodine is preferably 1:1 to 1.5, more preferably 1:1, 1:1.3 or 1:1.5.

[0050] In the present invention, the anhydrous aprotic solvent preferably includes at least one of NMP, DMAc, TMS, DMF, NBP, GVL, NFM, PC, NOP and 5-(dimethylamino)-2-methyl-5-oxopentanoic acid methyl ester (PolarClean), more preferably NMP, DMF, NFM or 5-(dimethylamino)-2-methyl-5-oxopentanoic acid methyl ester (PolarClean), the water content of the anhydrous aprotic solvent is preferably ≤100ppm, and the boiling point of the solvent is preferably >150°C.

[0051] In the present invention, the temperature of the thermal decomposition reaction is preferably 180-240°C, more preferably 180°C, 210°C or 240°C, and the time is preferably 4-8h.

[0052] In the present invention, the mass percentage of perfluoropropyl iodide in the mixture of perfluoropropyl iodide and perfluoroisopropyl iodide is preferably 80-98%, and the mass percentage of perfluoroisopropyl iodide is preferably 2-20%.

[0053] In the present invention, the yield of the thermal decomposition reaction can reach up to 85%.

[0054] After obtaining a mixture of perfluoropropyl iodide and perfluoroisopropyl iodide, the present invention conducts a free radical addition reaction on the mixture of perfluoropropyl iodide and perfluoroisopropyl iodide and 3,3,3-trifluoropropylene (HFO-1243zf) to obtain an intermediate reaction liquid, wherein the intermediate reaction liquid includes CF3CF2CF2CHICH2CF3 and (CF3)2-CFCHICHCF3.

[0055] In the present invention, the principle of the free radical addition reaction is shown in the following formula:

[0056]

[0057] In the present invention, the molar ratio of the mixture of perfluoropropyl iodide and perfluoroisopropyl iodide to HFO1243zf is preferably 1:1 to 1.5, more preferably 1:1, 1:1.3 or 1:1.5.

[0058] In the present invention, the free radical addition reaction is preferably carried out under high temperature and high pressure, and the reaction conditions of high temperature and high pressure preferably include: temperature of 160-220°C, time of 8-20h, pressure of 1-6MPa, more preferably 160°C / 20h, 190°C / 14h or 220°C / 8h.

[0059] In the present invention, the sum of the mass percentages of CF3CF2CF2CHICH2CF3 and (CF3)2-CFCHICHCF3 in the intermediate reaction solution is preferably 60% to 75%.

[0060] After obtaining the intermediate reaction liquid, the present invention treats the intermediate reaction liquid with an alkali-alcohol mixed liquid to eliminate HI, thereby obtaining the liquid cooling medium.

[0061] In the present invention, taking KOH / alcohol as an example, the principle of eliminating HI by treating with the alkali-alcohol mixture is as follows:

[0062] CF3CF2CF2CHICH2CF 3.. +·(CF3)2CFCHICH2CF3..+KOH / alcohol→CF3CF2CF2CH=CHCF3

[0063] +(CF3)2CFCH=CHCF 3.. +KI+H2O.

[0064] In the present invention, the alkali-alcohol mixed solution is preferably a KOH / alcohol solution or a NaOH / alcohol solution, and more preferably a KOH / methanol solution, a KOH / ethanol solution or a KOH / isopropanol solution.

[0065] In the present invention, the volume of alcohol in the alkali-alcohol mixture is preferably 2 / 5, and the mass percentage of KOH or NaOH in the alkali-alcohol mixture is preferably 30%.

[0066] In the present invention, the molar amount of the alkaline substance in the alkali-alcohol mixed solution is preferably twice the sum of the molar amounts of CF3CF2CF2CHICH2CF3 and (CF3)2-CFCHICHCF3.

[0067] In the present invention, after the alkali-alcohol mixed solution is treated to eliminate HI, the obtained reactants include CF3CF2CF2CH=CHCF3, (CF3)2CFCH=CHCF3, by-products, a small amount of unreacted perfluoropropyl iodide (CF3CF2CF2I) and perfluoroisopropyl iodide (CF3CFICF3).

[0068] In the present invention, the target crude product obtained by treating the alkali-alcohol mixed liquid to eliminate HI is preferably purified by distillation and impurities are removed to obtain the liquid cooling medium.

[0069] In the present invention, the distillation purification is preferably carried out in a distillation tower to collect fractions between 40 and 52° C., which contain CF3CF2CF2CH=CHCF3, (CF3)2CFCH=CHCF3 and very small amounts of CF3CF2CF2I and CF3CFICF3, and the content of CF3CFICF3 is preferably 0.

[0070] In the present invention, the impurity removal preferably includes the following steps: treating the fraction with NaHSO3 or Na2S2O4 solution, increasing the sum of the mass contents of the mixture of CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3 to ≥99%, and reducing the sum of the contents of CF3CF2CF2I and CF3CFICF3 to <0.001%.

[0071] The present invention also provides a liquid cooling medium obtained by the above preparation method, including CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3.

[0072] In the present invention, the mass percentage of CF3CF2CF2CH=CHCF3 in the liquid cooling medium is preferably 83-98.5%, and the mass percentage of (CF3)2CFCH=CHCF3 is preferably 1.5-17%.

[0073] In the present invention, the boiling point of the liquid cooling medium is preferably 50±1°C, the latent heat of vaporization is preferably 112±3KJ / Kg, the kinematic viscosity is preferably 0.34cts (25°C), the thermal conductivity is preferably 0.068~0.071W / m·k, the dielectric constant is preferably 1.9~2.1 (1kHZ), the ODP value is preferably 0, and the GWP value is preferably less than 20.

[0074] The present invention also provides the use of the liquid cooling medium described in the above technical solution as a two-phase immersion liquid cooling medium.

[0075] In the present invention, the application preferably includes the following steps: using the liquid cooling medium in an immersion liquid cooling heat dissipation system.

[0076] In the present invention, the application preferably includes using the liquid cooling medium for heat dissipation by immersion liquid cooling in thermal management of servers, data centers, energy storage, semiconductor manufacturing, charging equipment or new energy vehicles.

[0077] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0078] Example

[0079] The preparation method of the liquid cooling medium is carried out according to the following steps:

[0080] S1: n-Butyryl chloride is electrofluorinated in anhydrous hydrogen fluoride to form a mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride, which is then absorbed by an alkali solution (KOH solution) and dried to remove water to form a powder mixture of potassium perfluorobutyrate and potassium perfluoroisobutyrate salt or a powder mixture of sodium salt.

[0081] The electrolysis process conditions are shown in Table 1. It can be seen that when the electrolysis temperature is lower and the anhydrous hydrogen fluoride content is higher, the produced isobutyrate content is lower.

[0082] Table 1 Electrolysis process conditions

[0083]

[0084]

[0085] S2: A mixture of potassium perfluorobutyrate and potassium perfluoroisobutyrate (obtained in Example 8, 3 or 19) and iodine are heated at high temperature in a high-boiling anhydrous aprotic solvent to decompose and release a mixture of perfluoropropyl iodide and perfluoroisopropyl iodide; under different conditions of feed ratio, solvent type and reaction temperature, perfluoro-n-propyl iodide and isopropyl iodide have different yields and different ratios in the mixture. The feed reaction for preparing a mixture of perfluoro-n-propyl iodide and isopropyl iodide is shown in Tables 2 to 4.

[0086] Table 2 Feeding reaction of the mixture of Example 8 to prepare the mixture of perfluoropropyl iodide and isopropyl iodide

[0087]

[0088]

[0089] Table 3 Feeding reaction of the mixture of Example 3 to prepare the mixture of perfluoropropyl iodide and isopropyl iodide

[0090]

[0091]

[0092]

[0093] Table 4 Feeding reaction of the mixture of Example 19 to prepare the mixture of perfluoropropyl iodide and isopropyl iodide

[0094]

[0095]

[0096] S3: The mixture of perfluoropropyl iodide and perfluoroisopropyl iodide in S2 is reacted with HFO-1243zf under high temperature and high pressure conditions to obtain an intermediate reaction liquid having a structure mainly composed of a mixture of CF3CF2CF2CHICH2CF3 and (CF3)2CFCHICHCF3; the molar ratio of the mixture of perfluoropropyl iodide and perfluoroisopropyl iodide to HFO1243zf is 1:1-1.5. The data on the feed of the intermediate reaction liquid and the intermediate yield are shown in Table 5.

[0097] The perfluoro-n-propyl iodide / isopropyl iodide mixtures of Examples 64 to 66 are from the second group of Example 33; the perfluoro-n-propyl iodide / isopropyl iodide mixtures of Examples 67 to 69 are from the second group of Example 41; and the perfluoro-n-propyl iodide / isopropyl iodide mixtures of Examples 70 to 72 are from the third group of Example 45.

[0098] Table 5 Preparation of intermediate reaction liquid feeding and intermediate yield data table

[0099]

[0100]

[0101]

[0102] Note: In Table 5, intermediate A is CF3CF2CF2CHICH2CF3, and intermediate a is (CF3)2CFCHICHCF3.

[0103] S4: The intermediate mixture of CF3CF2CF2CHICH2CF3 and (CF3)2CFCHICHCF3 in S3 is treated with an alkali-alcohol mixture to eliminate HI to obtain the target crude product, and the elimination reaction temperature is 60°C. The alkali-alcohol mixture used is a KOH ethanol solution with a mass concentration of 30%, and the amount of KOH used is 2 times the molar amount of the intermediate mixture. After distillation and purification to remove impurities, the liquid cooling medium for two-phase immersion is obtained: a hydrofluoroolefin mixture with a chemical structure of CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3.

[0104] According to the different ratios of CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3 in the intermediates used, target liquid cooling working fluids with different ratios can be prepared: a mixed working fluid of CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3, with the mass percentages being: 83%~98.5%: 17%~1.5%.

[0105] After the intermediate reaction liquid in Example 64 is treated with an alkali-alcohol mixed solution, the product is distilled and purified to obtain the hydrofluoroolefin mixture of Example 76; after the intermediate reaction liquid in Example 66 is treated with an alkali-alcohol mixed solution, the product is distilled and purified to obtain the hydrofluoroolefin mixture of Example 77; after the intermediate reaction liquid in Example 67 is treated with an alkali-alcohol mixed solution, the product is distilled and purified to obtain the hydrofluoroolefin mixture of Example 78; after the intermediate reaction liquid in Example 72 is treated with an alkali-alcohol mixed solution, the product is distilled and purified to obtain the hydrofluoroolefin mixture of Example 79; after the intermediate reaction liquid in Example 73 is treated with an alkali-alcohol mixed solution, the product is distilled and purified to obtain the hydrofluoroolefin mixture of Example 80; after the intermediate reaction liquid in Example 74 is treated with an alkali-alcohol mixed solution, the product is distilled and purified to obtain the hydrofluoroolefin mixture of Example 81.

[0106] The physical property tests of mixed hydrofluoroolefin mixtures of CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3 in different proportions are shown in Table 6.

[0107] Table 6 Physical property test results of hydrofluoroolefin mixture

[0108]

[0109] The hydrofluoroolefin mixture prepared by the above method contains two material components, CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3, and the mixture is spontaneously generated during the preparation process of the present invention, and there is no need to separate the two. The above hydrofluoroolefin mixtures in different proportions can be directly used as two-phase immersion liquid cooling working fluids. The preparation method provided by the present invention is of great significance for preparing candidate working fluids with excellent performance and stable quality for immersion cooling systems.

[0110] The mixed hydrofluoroolefin working fluids obtained in Examples 76-77 and 80-81 are respectively applied to a two-phase immersion cooling system, which has the advantages of efficient heat dissipation and temperature control, and can keep the internal temperature of the liquid cooling system within the range of 35-60°C, with obvious advantages in energy saving and consumption reduction.

[0111] The hydrofluoroolefin mixed liquid obtained in Example 76, Example 77, Example 80 and Example 81 was used as a coolant and added into a sealed shell and a coolant tank in a two-phase immersion cooling system. A rack-mounted server Dell R750XS was immersed in the coolant and operated continuously for 48 hours. The temperature changes of the CPU components were observed, as shown in Table 8.

[0112] Various physical property tests were performed on the substances used as coolants in Comparative Examples 1 to 7, as shown in Table 7.

[0113] Table 7 Physical property test results of the coolant in Comparative Examples 1 to 7

[0114]

[0115] The commercially available substances of Comparative Examples 1 to 7 were used as coolants, added into the sealed shell and coolant tank of the two-phase immersion cooling system, and the rack-mounted server Dell R750XS was immersed in the coolant and operated continuously for 48 hours, and the temperature changes of the CPU components were observed, as shown in Table 8.

[0116] Table 8 Refrigeration effect test results data

[0117]

[0118]

[0119] Note: In Table 8, ①: CF3CF2CF2CH=CHCF3 / (CF3)2CFCH=CHCF3 is 83 / 17; ②: CF3CF2CF2CH=CHCF3 / (CF3)2CFCH=CHCF3 is 85.7 / 14.3; ③: CF3CF2CF2CH=CHCF3 / (CF3)2CFCH=CHCF3 is 95.2 / 4.8; ④: CF3CF2CF2CH=CHCF3 / (CF3)2CFCH=CHCF3 is 98.5 / 1.5.

[0120] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a liquid cooling medium, characterized in that: The following steps are involved: Electrofluorinating an n-butyl compound in anhydrous hydrogen fluoride to obtain a mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride, and absorbing the mixed gas of perfluorobutyryl fluoride and perfluoroisobutyryl fluoride with an alkali solution to obtain a mixture of perfluorobutyrate and perfluoroisobutyrate; The mixture of perfluorobutyrate and perfluoroisobutyrate is subjected to a thermal decomposition reaction with iodine in an anhydrous aprotic solvent to obtain a mixture of perfluoropropyl iodide and perfluoroisopropyl iodide; The mixture of perfluoropropyl iodide and perfluoroisopropyl iodide is subjected to a free radical addition reaction with 3,3,3-trifluoropropylene to obtain an intermediate reaction liquid, wherein the intermediate reaction liquid includes CF3CF2CF2CHICH2CF3 and (CF3)2-CFCHICH2CF3; Treating the intermediate reaction liquid with an alkali-alcohol mixture to eliminate HI, thereby obtaining the liquid cooling medium; The n-butyl compound includes one or more of n-butyryl chloride, n-butyryl fluoride and n-butyric acid; The molar ratio of the n-butyl compound to anhydrous hydrogen fluoride is 1:8-16; The temperature of the electrolytic fluorination is -10 to 10°C; The molar ratio of the mixture of perfluorobutyrate and perfluoroisobutyrate to iodine is 1:1 to 1.5; The temperature of the thermal decomposition reaction is 180-240°C and the time is 4-8h; In the mixture of perfluoropropyl iodide and perfluoroisopropyl iodide, the mass percentage of perfluoropropyl iodide is 80-98%, and the mass percentage of perfluoroisopropyl iodide is 2-20%; The liquid cooling medium includes CF3CF2CF2CH=CHCF3 and (CF3)2CFCH=CHCF3.

2. The liquid cooling medium prepared by the preparation method according to claim 1, characterized in that: The mass percentage of CF3CF2CF2CH=CHCF3 in the liquid cooling medium is 83-98.5%, and the mass percentage of (CF3)2CFCH=CHCF3 is 1.5-17%.

3. Application of the liquid cooling medium described in claim 2 as a two-phase immersion liquid cooling medium.

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