Direct contact type mineral oil dielectric cooling liquid and preparation method thereof

Abstract

The invention relates to the technical field of liquid cooling of electronic devices of IT equipment, in particular to direct contact type mineral oil dielectric cooling liquid and a preparation method thereof.The direct contact type mineral oil dielectric cooling liquid is prepared from, by mass, 99.2%-99.8% of base oil and 0.2%-0.8% of additives; the base oil is mineral paraffin-based white oil, and the additives comprise an antioxidant and a light stabilizer. The direct contact type mineral oil dielectric cooling liquid disclosed by the invention is colorless and transparent, has good flowing property, fireproof safety performance, heat-conducting property, insulating property and oxidation stability, is free of aromatic hydrocarbon, heteroatom, acidic substance and corrosion, is excellent in environmental protection property, less in water absorption in a use process, lower in evaporation loss, good in stability and long in service life. The material has excellent compatibility with IT equipment materials, power lines and network cables, is not liable to become yellow under the influence of light and heat, is simple and convenient to operate in the preparation process, and is easy to realize industrial large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of liquid cooling of electronic devices of IT equipment, and is a direct contact type mineral oil dielectric cooling liquid and a preparation method thereof. Background Art

[0002] With the innovative development of technologies such as artificial intelligence, cloud computing, big data, and blockchain, as well as the advent of the 5G communication era, computer technology has developed rapidly. In order to meet the challenges of network processing performance, IT equipment has continuously improved its processing capabilities and integration, resulting in a steady increase in power density. In addition to the huge energy consumption problem caused by these changes, high heat density also puts higher requirements on refrigeration equipment and technology.

[0003] Traditional air cooling technology faces bottlenecks in high heat density scenarios, and the heat dissipation efficiency can no longer keep up with the computing efficiency. Although the industry has been constantly innovating air cooling systems, the heat carrying capacity of air is far lower than that of liquid, and the cooling capacity of liquid is 1,000 to 3,000 times that of air. Liquid cooling technology has the characteristics of high efficiency, low energy loss, low dependence on buildings for deployment, and quietness and safety. Compared with air cooling, it has incomparable technical advantages. It is an excellent heat dissipation solution that can be applied to scenarios that require a significant increase in computing power, energy efficiency, and deployment density. It can meet the deployment of higher density under conditions of insufficient site power capacity. Therefore, when air cooling is no longer able to cope with high heat, liquid cooling technology gradually moves from behind the scenes to the foreground, attracting widespread attention in the industry.

[0004] In simple terms, the principle of liquid cooling is to use heat convection or heat conduction to remove the heat dissipated by the server through immersion or flow of liquid. The main liquid cooling methods for servers include cold plate liquid cooling, immersion liquid cooling and spray liquid cooling.

[0005] At present, the coolants used in liquid cooling technology mainly include water and fluorinated liquid. Among them: water is a non-insulator and can only be used in non-direct contact cold plate liquid cooling technology. Once a leak occurs, it will cause fatal damage to IT equipment; fluorinated liquid is the most widely used direct contact coolant for immersion, but it is expensive, volatile, has high cost of use, high density, and high load-bearing requirements for buildings. Because water and fluorinated liquid have the above disadvantages as coolants, the relevant industry actively studies and explores the use of oil coolants in direct contact liquid cooling, most of which are studies on synthetic oil and silicone oil coolants.

[0006] Due to the characteristics of electronic components in IT equipment, the coolant in direct contact with them should have good insulation performance, thermal conductivity, compatibility with materials, non-flammable safety performance, antioxidant stability and eco-friendly performance. At the same time, in order to promptly remove the heat emitted by electronic components, easy to clean and low pump power consumption, the coolant should have good flow performance. In order to keep the coolant's viscosity stable under low temperature and working temperature conditions, the coolant should have a higher viscosity index. At present, whether it is commercialized or patented coolants provided in public literature, the performance still needs to be improved when used as direct contact coolants for electronic components of IT equipment.

[0007] A Chinese patent document with publication number CN110862806A discloses an electronic device coolant and a preparation method thereof, wherein dimethyl silicone oil, natural ester oil or synthetic ester oil is used as a base oil and an antioxidant and a dispersant are added to prepare the electronic device coolant. A Chinese patent document with publication number CN113861948A discloses a coolant and a preparation method thereof, wherein an immersion liquid cooling coolant is prepared using a defoamer, an oily epoxy resin, a dispersant, a siloxane, a flash point enhancer, and terminal hydroxyl polybutadiene as raw materials. Although synthetic oil or silicone oil is cheaper than fluorinated liquid, their prices are still relatively expensive. In comparison, mineral oil is cheap and has a good application prospect as a coolant for IT equipment.

[0008] In the existing technology of using mineral oil as IT equipment coolant, a Chinese patent document with publication number CN107502309A discloses a coolant and its preparation method, which is prepared by adding a trace amount of antioxidant, defoamer and dispersant to the traditional mineral base oil to obtain a coolant, which can be suitable for immersion direct cooling of IT equipment in an open environment. However, the coolant is easily yellowed by light and heat, and the coolant has oxidation stability (the antioxidant content is far less than the recommended dose, and the antioxidant performance can be ignored), non-volatile performance (evaporation loss of 360h is as high as 0.93%), insulation performance (breakdown voltage is only 30kV), low-temperature flow performance (pour point -27℃), compatibility with liquid cooling system materials and friendly environmental protection performance to the ecological environment, etc. There is still room for improvement. In addition, there are many types of coolant additives and the composition is complex, which can easily make the coolant system unstable and affect the performance. Summary of the invention

[0009] The present invention provides a direct contact mineral oil dielectric coolant and a preparation method thereof, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of the prior mineral oil dielectric coolant being easily yellowed by light and heat, and having insufficient oxidation stability, volatility, insulation, low-temperature flowability, material compatibility and poor environmental protection.

[0010] One of the technical solutions of the present invention is achieved through the following measures: a direct contact mineral oil dielectric coolant, the raw materials of which include 99.2% to 99.8% of base oil and 0.2% to 0.8% of additives by mass percentage; the base oil is mineral paraffin-based white oil, and the additives include antioxidants and light stabilizers.

[0011] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The above-mentioned direct contact type mineral oil dielectric coolant is prepared according to the following method: add the required amount of light stabilizer and antioxidant to the required amount of base oil in sequence, heat to 60°C to 70°C, stir until clear and transparent, cool to room temperature, and filter to obtain the direct contact type mineral oil dielectric coolant.

[0012] The proportion of saturated chain alkanes in the above-mentioned mineral paraffin-based white oil is 20% to 80%, and the proportion of cycloalkanes with less than five rings is 20% to 80%.

[0013] The mineral paraffin-based white oil has zero aromatic content and contains no sulfur, nitrogen and oxygen atoms.

[0014] The antioxidant is one or more of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol and alkyl diphenylamine, and the amount of the antioxidant is 0.19% to 0.7% of the total mass of the direct contact mineral oil dielectric coolant.

[0015] The above-mentioned light stabilizer is one or more of a benzophenone light stabilizer and a benzotriazole light stabilizer, and the amount of the light stabilizer is 0.01% to 0.1% of the total mass of the direct contact mineral oil dielectric coolant.

[0016] The light stabilizer is one or more of UV326, UV531 and UV328.

[0017] The kinematic viscosity of the direct contact mineral oil dielectric coolant at 40°C is 3 mm 2 / s to 50mm 2 / s.

[0018] The flash point of the mineral paraffin-based white oil is greater than 166°C, the pour point is less than -24°C, the thermal conductivity (40°C) is greater than 0.1310 W / m·K, and the breakdown voltage is greater than 60 kV.

[0019] The second technical solution of the present invention is achieved by the following measures: a method for preparing a direct contact mineral oil dielectric coolant, which is carried out according to the following steps: adding the required amount of light stabilizer and antioxidant to the required amount of base oil in sequence, heating to 60°C to 70°C, stirring until clear and transparent, cooling to room temperature, and filtering to obtain the direct contact mineral oil dielectric coolant.

[0020] The direct contact mineral oil dielectric coolant of the present invention is colorless and transparent, has good flowability, fire safety performance, thermal conductivity, insulation performance and oxidation stability, is free of aromatic hydrocarbons and heteroatoms, free of acidic substances, non-corrosive, and has excellent environmental protection. It absorbs less water during use, has low evaporation loss, has good stability, has excellent compatibility with IT equipment materials, power lines, and network cables, and is not easily affected by light and heat and turns yellow. The mineral oil dielectric coolant of the present invention is easier to prepare and has higher economic value than synthetic oil or silicone oil coolants, and is easy to achieve industrial-scale production. DETAILED DESCRIPTION

[0021] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; the normal temperature and room temperature in the present invention generally refer to the temperature of 15°C to 25°C, and are generally defined as 25°C.

[0022] The present invention will be further described below in conjunction with embodiments: Embodiment 1: The raw materials of the direct contact mineral oil dielectric coolant include 99.2% to 99.8% of base oil and 0.2% to 0.8% of additives by mass percentage; the base oil is mineral paraffin-based white oil, and the additives include antioxidants and light stabilizers.

[0023] Example 2: As an optimization of the above example, the direct contact type mineral oil dielectric coolant is prepared according to the following method: add the required amount of light stabilizer and antioxidant to the required amount of base oil in sequence, heat to 60°C to 70°C, stir until clear and transparent, cool to room temperature, and filter to obtain the direct contact type mineral oil dielectric coolant. At a temperature of 60°C to 70°C, the light stabilizer can be fully dissolved.

[0024] Example 3: As an optimization of the above example, the proportion of saturated paraffins in mineral paraffin-based white oil is 20% to 80% and the proportion of cycloalkanes within five rings is 20% to 80%. Cycloalkanes within five rings are monocyclic cycloalkanes, bicyclic cycloalkanes, tricyclic cycloalkanes, tetracyclic cycloalkanes and pentacyclic cycloalkanes.

[0025] Example 4: As an optimization of the above example, the aromatic content in the mineral paraffin-based white oil is zero, and it does not contain sulfur atoms, nitrogen atoms, and oxygen atoms. The base oil selected in the present invention is a mineral paraffin-based white oil, which has no toxicity and skin irritation to organisms and has higher safety and friendliness. At the same time, since it does not contain heteroatoms, the chemical stability of the coolant using the mineral paraffin-based white oil as the base oil is also better.

[0026] Example 5: As an optimization of the above example, the antioxidant is one or more of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol and alkyl diphenylamine, and the amount of the antioxidant is 0.19% to 0.7% of the total mass of the direct contact mineral oil dielectric coolant.

[0027] Example 6: As an optimization of the above example, the light stabilizer is one or more of a benzophenone light stabilizer and a benzotriazole light stabilizer, and the amount of the light stabilizer is 0.01% to 0.1% of the total mass of the direct contact mineral oil dielectric coolant.

[0028] Embodiment 7: As an optimization of the above embodiment, the light stabilizer is one or more of UV326, UV531 and UV328. UV326, UV531 and UV328 are ultraviolet absorbers UV326, UV531 and UV328.

[0029] Example 8: As an optimization of the above example, the kinematic viscosity of the direct contact mineral oil dielectric coolant at 40°C is 3 mm 2 / s to 50mm 2 / s.

[0030] Example 9: As an optimization of the above example, the flash point of mineral paraffin-based white oil is greater than 166°C, the pour point is less than -24°C, the thermal conductivity (40°C) is greater than 0.1310 W / m·K, and the breakdown voltage is greater than 60 kV.

[0031] The raw materials of the direct contact mineral oil dielectric coolant of the present invention are mineral paraffin-based white oil, antioxidant and light stabilizer, wherein the mineral paraffin-based white oil has outstanding advantages such as high flash point, good thermal conductivity, non-volatile, good compatibility with IT equipment materials, no aromatic hydrocarbons and heteroatoms, stable properties, good environmental protection, etc., which can meet many performance requirements of dielectric coolants; antioxidants have greatly improved the oxidation stability of dielectric coolants; light stabilizers can prevent the coolant from turning yellow due to light and heat, and can further increase the oxidation stability. In addition, it is precisely because the base oil of the direct contact dielectric coolant adopts paraffin-based white oil with excellent performance that the base oil itself can meet many performance requirements of dielectric coolant products. Therefore, there is no need to add additives such as flash point enhancers and oily epoxy resins, and there is no need to add dispersants to make the coolant have good stability. The present invention only needs to add antioxidants and light stabilizers on the basis of mineral paraffin-based white oil to prepare a dielectric coolant product with excellent performance. The composition is simple and can well meet the needs of IT equipment liquid cooling systems.

[0032] Example 10: The direct contact mineral oil dielectric coolant, the raw materials include by mass percentage: mineral paraffin white oil 99.34%; 2,6-di-tert-butyl-p-cresol 0.6%; light stabilizer UV326 0.06%. Mineral paraffin white oil, 2,6-di-tert-butyl-p-cresol, and light stabilizer UV326 are weighed according to the above mass percentages, and light stabilizer UV326 and 2,6-di-tert-butyl-p-cresol are added to the mineral paraffin white oil in sequence, and the mixture is heated to 60°C, stirred and mixed until clear and transparent, and then cooled to room temperature, and filtered to obtain the direct contact mineral oil dielectric coolant.

[0033] Example 11: The direct contact type mineral oil dielectric coolant, the raw materials include by mass percentage: mineral paraffin-based white oil 99.2%; 2,6-di-tert-butylphenol 0.7%; light stabilizer UV326 0.1%. After weighing the mineral paraffin-based white oil, 2,6-di-tert-butylphenol, and light stabilizer UV326 according to the above mass percentages, add light stabilizer UV326 and 2,6-di-tert-butylphenol to the mineral paraffin-based white oil in sequence, heat the mixture to 70°C, stir and mix until clear and transparent, then cool to room temperature, and filter to obtain the direct contact type mineral oil dielectric coolant.

[0034] Example 12: The direct contact type mineral oil dielectric coolant, the raw materials include by mass percentage: mineral paraffin-based white oil 99.8%; alkyl diphenylamine 0.19%; light stabilizer UV531 0.01%. Mineral paraffin-based white oil, alkyl diphenylamine, and light stabilizer UV531 are weighed according to the above mass percentages, and light stabilizer UV531 and alkyl diphenylamine are added to the mineral paraffin-based white oil in sequence, and the three are mixed, heated to 65°C, stirred and mixed until clear and transparent, and then cooled to room temperature, and filtered to obtain the direct contact type mineral oil dielectric coolant.

[0035] Comparative Example 1: Commercially available ordinary transformer oil type coolant.

[0036] Comparative Example 2: The difference from Example 12 is that no light stabilizer is added, and the other components and amounts are the same as Example 12.

[0037] Performance Test: The direct contact mineral oil dielectric coolants of Examples 10 to 12 and the coolant of Comparative Example 1 were tested, and the test results are shown in Table 1. As can be seen from Table 1, the aromatic content, sulfur and nitrogen heteroatoms of the direct contact mineral oil dielectric coolants of Examples 10 to 12 are 0, and the commercially available ordinary transformer oil coolants have a higher content of heteroatoms such as aromatics, sulfur, and nitrogen due to the composition of the base oil. This difference also makes the direct contact mineral oil dielectric coolant of the present invention more environmentally friendly and stable. The flash point, thermal conductivity, breakdown voltage, and rotating oxygen bomb of the direct contact mineral oil dielectric coolant of Examples 10 to 12 are all higher than those of the commercially available ordinary transformer oil coolant, indicating that the fire safety performance, thermal conductivity, insulation performance, and oxidation stability of the direct contact mineral oil dielectric coolant of the present invention are better than those of the commercially available ordinary transformer oil coolant. The acid value of the direct contact mineral oil dielectric coolant of Example 10 to Example 12 is 0, and the saturated water content and evaporation loss are lower than those of the common transformer oil type coolant on the market, indicating that the direct contact mineral oil dielectric coolant of the present invention contains no acidic substances, absorbs less water during use, and has lower evaporation loss; the direct contact mineral oil dielectric coolant is non-toxic and non-irritating to the skin, and is more environmentally friendly than the common transformer oil type coolant on the market; and its compatibility with IT equipment materials, power cables, and network cables is better than that of the common transformer oil type coolant on the market.

[0038] Light and thermal stability test: The direct contact mineral oil dielectric coolant of Example 12 and the coolant of Comparative Example 2 were tested for light and heat stability, and the test results are shown in Table 2. As can be seen from Table 2, the light and heat stability of Example 12 with 0.01% light stabilizer UV531 added is significantly better than that of the coolant of Comparative Example 2 without light stabilizer UV531, indicating that light stabilizer UV531 can effectively improve the light and heat stability of the coolant.

[0039] Choice of light stabilizer: Coolant decomposes under the influence of light during use, causing deterioration and discoloration, which will seriously affect the quality and performance of the coolant. Therefore, the light stability of the coolant is very important. In addition to using base oil with good light stability, the selection of ultraviolet absorbers (i.e. light stabilizers) is an important measure to ensure that the coolant maintains good light stability during long-term use.

[0040] The light stabilizers of triazine (triazine-5), salicylate (UV622), benzophenone (UV531, UV9), and benzotriazole (UV326, UV328) were added to the mineral paraffin-based white oil, mixed evenly, and then the light stability test was carried out. The addition amount of various light stabilizers and the test results are shown in Table 3. As can be seen from Table 3, the light stability performance of mineral paraffin-based white oil after adding triazine and salicylate ultraviolet absorbers is still poor. This is because these two types of ultraviolet absorbers have a wide absorption band and will absorb a small amount of visible light, thereby affecting the color of the coolant; benzotriazole and benzophenone ultraviolet absorbers have strong ability to absorb ultraviolet rays and do not absorb excess visible light, making the color of the coolant stable. In addition, the results of the compatibility test of different UV absorbers with IT liquid cooling system materials (see Table 4) also show that triazine and salicylate UV absorbers are incompatible with liquid cooling system materials, benzotriazole and benzophenone UV absorbers have good compatibility with materials, and benzotriazole and benzophenone UV absorbers will not affect other performance of the coolant.

[0041] In summary, the mineral oil-based dielectric coolant and the preparation method thereof of the present invention provide a direct contact type mineral oil dielectric coolant. The preparation method of the coolant is simple to operate. The obtained mineral oil-based dielectric coolant is colorless and transparent, has good flowability, fire safety performance, thermal conductivity, insulation performance and oxidation stability, is free of aromatic hydrocarbons and heteroatoms, free of acidic substances, non-corrosive, and has good environmental protection. It absorbs less water during use, is not easily affected by light and heat and turns yellow, has low evaporation loss, good stability, and excellent compatibility with IT equipment materials, power cables, and network cables.

[0042] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A direct contact mineral oil dielectric coolant, characterized in that The raw materials include 99.2% to 99.8% base oil and 0.2% to 0.8% additives by mass percentage; the base oil is mineral paraffin-based white oil, and the additives include antioxidants and light stabilizers.

2. The direct contact mineral oil dielectric coolant according to claim 1, characterized in that The preparation method is as follows: add the required amount of light stabilizer and antioxidant to the required amount of base oil in sequence, heat to 60°C to 70°C, stir until clear and transparent, cool to room temperature, and filter to obtain a direct contact mineral oil dielectric coolant.

3. The direct contact mineral oil dielectric coolant according to claim 1 or 2, characterized in that The proportion of saturated chain alkanes in mineral paraffin-based white oil is 20% to 80%, and the proportion of cycloalkanes with less than five rings is 20% to 80%.

4. The direct contact mineral oil dielectric coolant according to any one of claims 1 to 3, characterized in that Mineral paraffin-based white oils contain zero aromatic hydrocarbons and do not contain sulfur, nitrogen or oxygen atoms.

5. The direct contact mineral oil dielectric coolant according to claims 1 to 4, characterized in that The antioxidant is one or more of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol and alkyl diphenylamine, and the amount of the antioxidant is 0.19% to 0.7% of the total mass of the direct contact mineral oil dielectric coolant.

6. The direct contact mineral oil dielectric coolant according to any one of claims 1 to 5, characterized in that The light stabilizer is one or more of a benzophenone light stabilizer and a benzotriazole light stabilizer, and the amount of the light stabilizer is 0.01% to 0.1% of the total mass of the direct contact mineral oil dielectric coolant.

7. The direct contact mineral oil dielectric coolant according to any one of claims 1 to 6, characterized in that The light stabilizer is one or more of UV326, UV531 and UV328.

8. The direct contact mineral oil dielectric coolant according to any one of claims 1 to 7, characterized in that The kinematic viscosity of the direct contact mineral oil dielectric coolant at 40°C is 3 mm 2 / s to 50mm 2 / s.

9. The direct contact mineral oil dielectric coolant according to any one of claims 1 to 8, characterized in that The flash point of mineral paraffin-based white oil is >166°C, the pour point is <-24°C, the thermal conductivity is >0.1310W / m·K, and the breakdown voltage is >60kV.

10. A method for preparing the direct contact type mineral oil dielectric coolant according to claim 1 or 3 or 4 or 5 or 6 or 7 or 8 or 9, characterized in that Proceed as follows: add the required amount of light stabilizer and antioxidant to the required amount of base oil in sequence, heat to 60°C to 70°C, stir until clear and transparent, cool to room temperature, and filter to obtain a direct contact mineral oil dielectric coolant.

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