Low-density high-thermal-conductivity composite silicone oil cooling liquid and preparation method thereof

Abstract

The invention relates to the field of immersed coolants, and discloses a low-density high-thermal-conductivity composite silicone oil coolant and a preparation method thereof, the method comprises preparation of naphthyl-terminated aryl silicone oil and application of the naphthyl-terminated aryl silicone oil to a base liquid of the silicone oil coolant, and the thermal conductivity of the silicone oil coolant is improved. Dissolving dimethyldichlorosilane in tetrahydrofuran, dropwise adding a naphthalene Grignard reagent into the mixed solution, and after the reaction is finished, carrying out quenching, extraction and other processes to obtain dimethylnaphthalene aryl chlorosilane; adding a potassium carbonate solution into the dimethyl naphthyl aryl chlorosilane, and extracting after reaction to obtain dimethyl-naphthyl siloxane alcohol; adding a tin catalyst into the dimethyl-naphthyl siloxane alcohol, carrying out vacuum reaction, rectifying and purifying to obtain tetramethyl dinaphthyl disiloxane; the naphthyl-terminated aryl silicone oil is prepared by taking DMC as a raw material, KOH potassium as a catalyst and tetramethyl dinaphthyl disiloxane as an end capping agent. The composite silicone oil cooling liquid with low density, high specific heat capacity and stable structure is prepared by stirring, mixing and compounding.

Description

Technical Field

[0001] The present invention relates to the field of energy storage and heat transfer, and is used as a heat dissipation medium in immersion liquid cooling technology. It is mainly used in electronic components, IT servers, 5G base stations, etc. Background Art

[0002] With the accelerated development of the big data era, the heat dissipation demand of data centers is getting higher and higher. In order to meet PUE < 1.1, the traditional air cooling or cold plate cooling technology can no longer meet the fast and efficient cooling requirements of data centers. Compared with traditional air cooling or cold plate technology, immersion liquid cooling technology has the advantages of efficient cooling, energy saving and consumption reduction, quiet and low noise, and space saving. It will become an effective solution to the heat dissipation problem of data centers.

[0003] At present, the base liquid of immersion coolant is mainly composed of three categories: fluorinated liquid, carbon-based synthetic oil, and silicone oil. Among them, fluorinated liquid has a higher cost, high product density, heavy equipment load, relatively higher transportation energy consumption, and potential risk of damaging the ozone layer, so the demand for replacement is increasing; although the synthetic oil of carbon-based materials has certain cost advantages, it lacks structural stability, has a low flash point, and has a short service life; compared with fluorinated liquid and synthetic oil, silicone oil has the advantages of low viscosity, low density, structural stability, good compatibility, and moderate cost. It is currently a better material to replace fluorinated liquid. However, due to the limitations of its own properties, the specific heat capacity of ordinary dimethyl silicone oil is still a certain distance compared with fluorinated liquid. Improving the thermal conductivity and stability of silicone oil is a problem that needs to be solved urgently.

[0004] Chinese patent publication number CN116731689A discloses a method for preparing a silicone oil coolant, which enhances the thermal conductivity of the coolant by adding inorganic fillers such as silicon nitride and aluminum oxide to ordinary dimethyl silicone oil. However, the method has the following disadvantages: first, the silicone oil coolant prepared by adding inorganic fillers belongs to a heterogeneous system, which easily causes solid powder to deposit on the surface of the equipment and damage the equipment; second, the diluent used in the coolant contains substances such as chlorinated alkanes and olefins with low flash points, which are substances with high risk factors.

[0005] This patent uses independently developed silicone oil compounding technology and dimethyl silicone oil as the base liquid to prepare a composite silicone oil coolant with the following advantages: First, the product has a low density, which is less than 0.900g / cm 3 , which is only half the density of fluorinated liquid, is used in large data centers and communication base stations, reducing the load of equipment bearing devices and the carrying power of circulation pumps; secondly, the product has relatively high specific heat capacity and thermal conductivity, with a specific heat capacity of more than 1.95 J·g at 40°C. -1 ·K -1, thermal conductivity is greater than 0.190w / (m·K), and the heat dissipation performance is better than that of ordinary dimethyl silicone oil or synthetic oil; thirdly, the structure of silicone oil is stable, not easy to age and deteriorate, and has a long service life; fourthly, the composite silicone oil coolant is a homogeneous system, no additional thermal conductive powder needs to be added, it will not affect the insulation of the equipment, and there is no powder deposition.

[0006] In order to improve the specific heat capacity of composite silicone oil coolant, the following problems need to be solved: 1. Select a suitable modifier with low viscosity and high specific heat capacity, which is compatible with low-viscosity dimethyl silicone oil and has a stable structure and is not easy to deteriorate; 2. Explore the appropriate formula ratio to ensure that the density and specific heat capacity are within the appropriate range. Summary of the invention

[0007] In view of the shortcomings of the prior art, a method for preparing a high thermal conductivity terminal naphthalene aryl silicone oil is provided, and a low-density high thermal conductivity silicone oil coolant is prepared by compounding silicone oil. The raw materials used in the preparation method of the present invention are mainly dimethyl silicone oil, diphenyl silicone oil, terminal naphthalene aryl silicone oil and liquid paraffin, which reduces the density of silicone oil and increases the specific heat capacity of silicone oil. The density of the prepared composite silicone oil coolant is less than 0.900 g / cm 3 The viscosity of the coolant at 40°C is less than 20cSt, and the density is less than 0.900g / cm 3 , thermal conductivity is greater than 0.190w / (m·K). It is colorless and transparent, has good fluidity, and the solution is uniform and stable.

[0008] In order to achieve the above object, the present invention provides the following technical solutions: A low-density and high-thermal-conductivity composite silicone oil coolant, the coolant comprising base oil, modified silicone oil, and a regulator; The base oil is selected from dimethyl silicone oil; The modified silicone oil is selected from phenyl silicone oil and / or terminal naphthalene aryl silicone oil; The conditioning agent is selected from liquid paraffin oil.

[0009] In the above-mentioned low-density high-thermal-conductivity composite silicone oil coolant, The dimethyl silicone oil has a viscosity of 10-30 cSt at 25°C, a volatile matter of less than 0.30% (150°C for 3h), a flash point of more than 150°C, and an addition ratio of 45-60%, and is used as the base liquid in the coolant.

[0010] The dimethyl diphenyl silicone oil has a viscosity of 20-50 cSt at 25°C, a volatile matter of <0.10% (150°C 3h), a flash point of >200°C, and accounts for 10-45%, and is used to improve the thermal conductivity and heat resistance of the coolant.

[0011] The terminal naphthalene aromatic silicone oil has a viscosity of 30-50 cSt, a volatile matter of less than 0.10% (150°C 3h), a flash point of more than 250°C, and accounts for 10-45%, and is used to improve the thermal conductivity and heat resistance of the coolant.

[0012] In the above, when the modified silicone oil is dimethyl diphenyl silicone oil or terminal naphthalene aryl silicone oil, each accounts for 30-45%; when the modified silicone oil is a mixture of dimethyl diphenyl silicone oil and terminal naphthalene aryl silicone oil, the mixed ratio is 30-45%, and the dimethyl diphenyl silicone oil and terminal naphthalene aryl silicone oil can be in any ratio.

[0013] The liquid paraffin is a mixture of liquid hydrocarbons, the main component of which is a mixture of C16 to C31 normal isomeric alkanes, has good oxidation stability, chemical stability and light stability, a viscosity of 1 to 10 cSt, and accounts for 5 to 10%.

[0014] The preparation method of terminal naphthalene aryl silicone oil comprises the following steps: (1) Dissolve dimethyldichlorosilane in tetrahydrofuran, slowly add 2-naphthylmagnesium bromide Grignard reagent, and after the reaction is completed, perform quenching and extraction steps to obtain dimethylnaphthyl aryl chlorosilane; (2) adding potassium carbonate solution to dimethylnaphthyl aryl chlorosilane, stirring and reacting for 6 to 8 hours, and extracting to obtain dimethylnaphthyl siloxane alcohol; (3) Adding dibutyltin dilaurate as a catalyst to dimethylnaphthylsiloxane, reacting at 110-120° C. under vacuum for 1-3 hours, and after the reaction is completed, rectifying and purifying to obtain tetramethyldinaphthyldisiloxane; (4) Using DMC as raw material, potassium KOH as catalyst, and tetramethyl dinaphthyl disiloxane as capping agent, terminal naphthalene aryl silicone oil was prepared.

[0015] The mass concentration of the potassium carbonate solution is 10-20%. The 2-naphthylmagnesium bromide Grignard reagent can be obtained through commercial channels, product CAS: 21473-01-8.

[0016] The coolant further contains additives, which include antioxidants, corrosion inhibitors and stabilizers; The antioxidant comprises: one or a combination of 2,6-di-tert-butyl-p-cresol and tert-butyl hydroquinone; The corrosion inhibitor includes: one or a combination of benzimidazole and tributyl phosphate; and can prevent corrosion and oxidation of metal materials in IT communication equipment.

[0017] The stabilizer includes: one or a combination of benzoic acid and citric acid; The total dosage of additives is 0-2%.

[0018] Another technical solution of the present invention is to provide a method for preparing a low-density and high-thermal-conductivity composite silicone oil coolant, the method for preparing the composite silicone oil coolant comprising: Adding modified silicone oil to base oil and stirring to obtain a first mixed liquid; adding a regulator to the first mixed liquid and stirring to obtain a second mixed liquid, that is, obtaining a composite silicone oil coolant; Alternatively, the modified silicone oil is added to the base oil and stirred to obtain a first mixed liquid; a regulator is added to the first mixed liquid, and stirred to obtain a second mixed liquid; an auxiliary agent is added to the second mixed liquid to obtain a third mixed liquid, that is, another composite silicone oil coolant is obtained.

[0019] Adding phenyl silicone oil and / or terminal naphthalene aryl silicone oil to dimethyl silicone oil in 3-4 times, setting the stirring speed, to obtain a first mixed liquid; adding liquid paraffin oil to the first mixed liquid in 2-3 times, setting the stirring speed, to obtain a second mixed liquid, and treating the second mixed liquid (in some embodiments, it can also be ultrasonically treated) to obtain a composite silicone oil coolant; Alternatively, phenyl silicone oil and / or terminal naphthalene aryl silicone oil is added to dimethyl silicone oil in 3 to 4 times, and the stirring speed is set to obtain a first mixed liquid; liquid paraffin oil is added to the first mixed liquid in 2 to 3 times, and the stirring speed is set to obtain a second mixed liquid; an auxiliary agent is added to the second mixed liquid, and the stirring speed is set to obtain a third mixed liquid; the third mixed liquid is treated (in some embodiments, it can also be ultrasonically treated) to prepare another composite silicone oil coolant.

[0020] The stirring speed for each mixing is 1000~2000rpm / min, and the stirring time for each mixing is 1~2h.

[0021] In some specific embodiments, the method for preparing the low-density high-thermal-conductivity silicone oil coolant comprises the following steps: 1. Prepare or weigh the components according to the above formula; 2. Place 50-60% dimethyl silicone oil in an open container and start stirring at a rate of 1000-1500 rpm / min; 3. Divide 20-30% of diphenyl silicone oil or naphthyl silicone oil into three portions, stir each portion for 10 minutes, and slowly pour the three portions into the stirring base liquid in turn, stirring and mixing for 1-2 hours; 4. Divide 5~20% liquid paraffin into two parts, increase the speed to 1500~2000rpm / min, slowly pour them into the liquid one by one, and stir and mix for 1~2h; Optionally, the method further comprises step 5. adding an antioxidant, a stabilizer and a corrosion inhibitor in sequence, maintaining a rotation speed of 1500-2000 rpm / min, and continuing stirring for 1-2 hours to obtain a silicone oil coolant, wherein the amount of the antioxidant, the stabilizer and the corrosion inhibitor is ≤2%.

[0022] The present invention has the following beneficial effects: 1. The organic silicone oil product used in the present invention has a low density, which is only half of the density of the fluorinated liquid. It is applied to large data centers and communication base stations, reducing the load of the equipment bearing device and the carrying power of the circulation pump; 2. The diphenyl silicone oil and terminal naphthalene aryl silicone oil used in the present invention have relatively high specific heat capacity, and their heat dissipation performance is better than that of ordinary dimethyl silicone oil or synthetic oil, and can improve the specific heat capacity of silicone oil coolant; 3. The organic silicone oil used in the present invention has a stable structure, is not easy to age and deteriorate, and has a long service life; 4. The composite silicone oil coolant prepared by the present invention is a homogeneous system without powder deposition and will not affect the insulation of the equipment.

[0023] 5. The coolant of the present invention has the characteristics of low toxicity, high insulation, inertness and strong material compatibility. DETAILED DESCRIPTION

[0024] The present invention is further explained below with reference to the examples, but the examples do not limit the present invention in any form.

[0025] Example 1 According to the composite immersion coolant provided in Example 1, the proportions of the raw material components are: 45% dimethyl silicone oil, 45% diphenyl silicone oil, 8% liquid paraffin oil, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid.

[0026] The preparation method of the immersion coolant is as follows: (1) Place dimethyl silicone oil in an open container, start stirring, and adjust the stirring rate to 1200 rpm / min; (2) Divide the diphenyl silicone oil into three portions, stir each portion for 10 minutes, and slowly pour the three portions into the stirring base liquid in sequence, stirring and mixing for 1 to 2 hours; (3) Divide the liquid paraffin into two parts, increase the speed to 1500~2000rpm / min, slowly pour them into the liquid one by one, stir and mix for 1~2h, and adjust the speed to 1500rpm / min; (4) Add antioxidant, stabilizer and corrosion inhibitor in proportion, maintain the rotation speed at 2000 rpm / min, and continue stirring for 1 to 2 hours to obtain silicone oil coolant.

[0027] Example 2 According to the composite immersion cooling liquid provided in Example 2, the proportions of the raw material components are: 55% dimethyl silicone oil, 35% diphenyl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as the steps in Example 1.

[0028] Example 3 According to the composite immersion cooling liquid provided in Example 3, the proportions of the raw material components are: 60% dimethyl silicone oil, 30% diphenyl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as the steps in Example 1.

[0029] Example 4 According to the composite immersion cooling liquid provided in Example 4, the proportions of the raw material components are: 45% dimethyl silicone oil, 45% terminal naphthalene aryl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as the steps in Example 1.

[0030] The preparation method of the terminal naphthalene aryl silicone oil is characterized by: (1) dissolving dimethyldichlorosilane in tetrahydrofuran, and slowly dropping 2-naphthylmagnesium bromide Grignard reagent into the mixed solution at a molar ratio of 1:1 at 90°C, and after the reaction is completed, quenching, extraction and other processes are performed to obtain dimethylnaphthalene aryl chlorosilane; (2) adding potassium carbonate solution (concentration 15%) to dimethylnaphthalene aryl chlorosilane, stirring and reacting for 6-8 hours, and extracting to obtain dimethylnaphthalene siloxane alcohol; (3) adding 0.1% dibutyltin dilaurate catalyst to dimethylnaphthalene siloxane alcohol, vacuumizing and reacting at 120°C for 2-3 hours, and after the reaction is completed, distilling and purifying to obtain tetramethyldinaphthyl disiloxane; (4) using DMC as a raw material, potassium KOH as a catalyst, and tetramethyldinaphthyl disiloxane as a capping agent to prepare the terminal naphthalene aryl silicone oil.

[0031] Example 5 According to the composite immersion cooling liquid provided in Example 5, the proportions of the raw material components are: 55% dimethyl silicone oil, 35% terminal naphthalene aryl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as the steps in Example 1.

[0032] Example 6 According to the composite immersion cooling liquid provided in Example 6, the proportions of the raw material components are: 60% dimethyl silicone oil, 30% terminal naphthalene aryl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as the steps in Example 1.

[0033] Example 7 According to the composite immersion cooling liquid provided in Example 7, the proportions of the raw material components are: 60% dimethyl silicone oil, 20% diphenyl silicone oil, 10% terminal naphthalene aryl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as the steps in Example 1.

[0034] Example 8 According to the composite immersion cooling liquid provided in Example 8, the proportions of the raw material components are: 60% dimethyl silicone oil, 10% diphenyl silicone oil, 20% terminal naphthalene aryl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as the steps in Example 1.

[0035] Comparative Example 1 The composite immersion cooling liquid provided in Comparative Example 1 has the following raw material components: 90% dimethyl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as that of Example 1.

[0036] Comparative Example 2 The composite immersion cooling liquid provided in Comparative Example 2 has the following raw material components: 98% dimethyl silicone oil, 8% liquid paraffin, 0.3% 2,6-di-tert-butyl-p-cresol, 0.2% tert-butyl hydroquinone, 0.6% benzimidazole, 0.4% tributyl phosphate, 0.3% benzoic acid, and 0.2% citric acid. The preparation method is the same as that of Example 1.

[0037] Comparative Example 3 The composite immersion coolant provided in Comparative Example 3 uses single-component dimethyl silicone oil as the heat exchange medium of the coolant, and the dimethyl silicone oil accounts for 100%.

[0038] The main test indicators of the composite immersion coolant prepared in the above Examples 1-8 and Comparative Examples 1-3 are compared as follows: Table 1 Composite immersion coolant test data table Test items Kinematic viscosityKinematic viscositycSt(40℃)cSt(40℃) <![CDATA[Density g / cm 3 > Flash point (℃) Specific heat capacity at 40℃40℃ specific heat capacity kJ / (kg·K) kJ / (kg·K) Thermal conductivity Thermal conductivity w / (m·K)w / (m·K) Dielectric strength (kV) Example 1 19.2 0.861 170 1.988 0.197 35.3 Example 2 18.5 0.852 167 1.975 0.193 35.7 Example 3 16.7 0.868 161 1.967 0.191 35.6 Example 4 19.5 0.887 183 2.253 0.201 36.1 Example 5 19.1 0.876 178 2.241 0.204 36.3 Example 6 18.3 0.873 182 2.105 0.210 36.5 Example 7 17.1 0.869 181 2.312 0.212 36.8 Example 8 18.0 0.871 180 2.301 0.215 36.9 Comparative Example 1 8.0 0.856 157 1.775 0.170 35.2 Comparative Example 2 8.3 0.927 175 1.778 0.171 35.6 Comparative Example 3 8.8 0.929 177 1.776 0.173 35.7 It can be seen from Table 1 that the composite immersion coolant prepared by the present invention has a relatively low density, which is less than 0.900 g / cm 3 , which can significantly reduce the load-bearing capacity of the equipment and the load pressure of the circulating pump. By comparing Examples 1-8 with (Comparative Examples 2-3), it can be seen that the addition of liquid paraffin oil can significantly reduce the density of the silicone oil coolant; by comparing Examples 1-8 with (Comparative Examples 1-3), it can be seen that the increase in the proportion of diphenyl silicone oil and / or naphthyl silicone oil can significantly increase the specific heat capacity and thermal conductivity of silicone oil, and the specific heat capacity is greater than 1.95 J·g -1 ·K -1 , the thermal conductivity is greater than 0.190 w / (m·K), indicating that the thermal conductivity of diphenyl silicone oil and / or naphthyl silicone oil is better than that of ordinary silicone oil.

[0039] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A low-density, high-thermal-conductivity composite silicone oil coolant, characterized in that: The coolant includes base oil, modified silicone oil and a regulator; The base oil is selected from dimethyl silicone oil; The modified silicone oil is selected from phenyl silicone oil and / or terminal naphthalene aryl silicone oil; The conditioning agent is selected from liquid paraffin oil.

2. The low-density, high-thermal-conductivity composite silicone oil coolant according to claim 1, characterized in that: Dimethyl silicone oil has a viscosity of 10~30cSt, accounting for 45~60%; The viscosity of phenyl silicone oil and / or terminal naphthalene aryl silicone oil is 20~50cSt, accounting for 10~45%; The viscosity of liquid paraffin oil is 1~10cSt, accounting for 5~10%.

3. The low-density, high-thermal-conductivity composite silicone oil coolant according to claim 2, characterized in that: When the modified silicone oil is phenyl silicone oil and terminal naphthalene aryl silicone oil, the usage ratio of the phenyl silicone oil and the terminal naphthalene aryl silicone oil is any ratio.

4. The low-density, high-thermal-conductivity composite silicone oil coolant according to claim 3, characterized in that: The preparation method of terminal naphthalene aryl silicone oil comprises the following steps: (1) Dissolve dimethyldichlorosilane in tetrahydrofuran, slowly add 2-naphthylmagnesium bromide Grignard reagent, and after the reaction is completed, perform quenching and extraction steps to obtain dimethylnaphthyl aryl chlorosilane; (2) adding potassium carbonate solution to dimethylnaphthyl aryl chlorosilane, stirring and reacting for 6 to 8 hours, and extracting to obtain dimethylnaphthyl siloxane alcohol; (3) Adding dibutyltin dilaurate as a catalyst to dimethylnaphthylsiloxane, reacting at 110-120° C. under vacuum for 1-3 hours, and after the reaction is completed, rectifying and purifying to obtain tetramethyldinaphthyldisiloxane; (4) Using DMC as raw material, potassium KOH as catalyst, and tetramethyl dinaphthyl disiloxane as capping agent, terminal naphthalene aryl silicone oil was prepared.

5. The low-density, high-thermal-conductivity composite silicone oil coolant according to claim 4, characterized in that: The mass concentration of potassium carbonate solution is 10-20%.

6. The low-density, high-thermal-conductivity composite silicone oil coolant according to any one of claims 1 to 5, characterized in that: The coolant further contains additives, which include antioxidants, corrosion inhibitors and stabilizers; The antioxidant comprises: one or a combination of 2,6-di-tert-butyl-p-cresol and tert-butyl hydroquinone; The corrosion inhibitor includes: one or a combination of benzimidazole and tributyl phosphate; The stabilizer includes: one or a combination of benzoic acid and citric acid; The total dosage of additives is 0-2%.

7. The method for preparing the low-density and high-thermal-conductivity composite silicone oil coolant according to claims 1 to 6, characterized in that: The preparation method of the composite silicone oil coolant comprises: Adding modified silicone oil to base oil and stirring to obtain a first mixed liquid; adding a regulator to the first mixed liquid and stirring to obtain a second mixed liquid, that is, obtaining a composite silicone oil coolant; Alternatively, the modified silicone oil is added to the base oil and stirred to obtain a first mixed liquid; a regulator is added to the first mixed liquid, and stirred to obtain a second mixed liquid; an auxiliary agent is added to the second mixed liquid to obtain a third mixed liquid, that is, another composite silicone oil coolant is obtained.

8. The method for preparing the low-density and high-thermal-conductivity composite silicone oil coolant according to claim 7, characterized in that: Adding phenyl silicone oil and / or terminal naphthalene aryl silicone oil to dimethyl silicone oil in 3 to 4 times, setting the stirring speed, to obtain a first mixed liquid; adding liquid paraffin oil to the first mixed liquid in 2 to 3 times, setting the stirring speed, to obtain a second mixed liquid, and treating the second mixed liquid to obtain a composite silicone oil coolant; Alternatively, phenyl silicone oil and / or terminal naphthalene aryl silicone oil is added to dimethyl silicone oil in 3 to 4 portions, and the stirring speed is set to obtain a first mixed solution; Liquid paraffin oil is added to the first mixed liquid in 2 to 3 times, and the stirring speed is set to obtain a second mixed liquid. The auxiliary agent is added to the second mixed liquid, and the stirring speed is set to obtain a third mixed liquid. The third mixed liquid is stirred to prepare another composite silicone oil coolant.

9. The method for preparing the low-density and high-thermal-conductivity composite silicone oil coolant according to claim 8, characterized in that: The stirring speed for each mixing is 1000~2000rpm / min, and the stirring time for each mixing is 1~2h.

10. The low-density and high-thermal-conductivity composite silicone oil coolant prepared by the method according to any one of claims 7 to 9, characterized in that: Density less than 0.900g / cm 3 , specific heat capacity greater than 1.95 J·g -1 ·K -1 , thermal conductivity is greater than 0.190w / (m·K).