Liquid cooling medium and application thereof

Abstract

The invention discloses a liquid cooling medium, and the liquid cooling medium comprises heptafluoro-2, 4, 4-tri (trifluoromethyl)-2-pentene. The liquid cooling medium disclosed by the invention has the advantages of high insulativity, no toxicity, no inflammability, good heat transfer performance and excellent material compatibility, and can be used for electronic equipment, data center server equipment, energy storage equipment, radar equipment, semiconductor processing equipment, electric automobile battery packs, automobile charging pile equipment and the like.

Description

Technical Field

[0001] The present invention relates to the field of liquid cooling working fluids, and particularly to a liquid cooling medium and its application. Background Art

[0002] In recent years, aerospace technology, defense technology, semiconductor processing, new energy industries, etc. have developed rapidly. The above fields are all inseparable from the rapid progress of electronic devices, which have higher power and smaller integrated volumes. The increase in electronic power brings an increase in the heat generation of the device, and the reduction in the integrated volume leads to a higher heat flux density under the same heat generation, thereby resulting in a rapid temperature rise of the device.

[0003] 10℃ rule: When the temperature is between 70℃ and 80℃, for every 10℃ increase, the reliability of electronic devices decreases by 50%. Therefore, the cooling problem has become a key factor restricting the development of related industries.

[0004] Liquid cooling is the optimal solution to solve the high heat generation of high-power power electronic devices. At present, most of the cold plate liquid cooling solutions using water-ethylene glycol solution are adopted. The advantage of cold plate liquid cooling lies in its lower cost and less modification to the structure of existing air-cooled devices, which is suitable for the liquid cooling transformation of existing air-cooled devices. However, since water-ethylene glycol solution is used as the coolant, there is a risk of corrosion to metal materials during the liquid flow in the pipeline. During long-term use, the component stability of the coolant is not good. At the same time, after the liquid leaks, it will cause fatal damage to electronic components. In addition, due to the design of the cold plate system, there are more intermediate heat conduction processes, and the processing technology of the cold plate itself will also bring a large contact thermal resistance, resulting in local hot spots in the equipment and reducing the operation reliability of the equipment.

[0005] Immersion heat transfer cooling media are mainly divided into two types: mineral oil and fluorinated liquid. Mineral oil has good insulation and initial investment cost advantages, but it is flammable. Once there is an electric spark or external fire, static electricity, etc. in the equipment, it is easy to catch fire and explode. In addition, the viscosity of mineral oil is about 10 times that of fluorinated liquid, and a greater pump power is required under the same flow state, resulting in higher operating costs. In terms of heat transfer, due to its larger viscosity, it has a higher flow boundary layer and thermal boundary layer during flow in the same equipment, resulting in poor heat transfer performance. Fluorinated liquid has advantages such as high insulation, low viscosity, adjustable boiling point for different scenarios, non-toxic and non-flammable, good long-term stability and material compatibility, and no ozone depletion potential, and is particularly suitable for the immersion liquid cooling system of electronic and electrical equipment. Summary of the Invention

[0006] The present invention provides a liquid cooling medium with high insulation, non-toxic, non-flammable, good heat transfer performance, and excellent material compatibility, which can be used in electronic devices, data center server devices, energy storage devices, radar devices, semiconductor processing devices, electric vehicle battery packs, and vehicle charging pile devices, etc.

[0007] The physical properties of the liquid cooling medium components described in the present invention are as follows:

[0008] Heptafluoro-2,4,4-tris(trifluoromethyl)-2-pentene, with a CAS number of 6189-06-6, has a molecular formula of C 8 F 16 , a molecular weight of 400.06, a standard boiling point measured by the static method experiment of 91.85 °C, a critical temperature of 210.67 °C, and a critical pressure of 1.253 MPa.

[0009] Hexafluoropropylene dimer, with a CAS number of 2070-70-4, has a molecular formula of C 6 F 12 , a molecular weight of 300.5, a standard boiling point measured by the static method experiment of 49 °C, a critical temperature of 169.92 °C, and a critical pressure of 1.732 MPa.

[0010] Hexafluoropropylene trimer, with a CAS number of 6792-31-0, has a molecular formula of C 9 F 18 , a molecular weight of 450.07, a standard boiling point measured by the static method experiment of 106.08 °C, a critical temperature of 243.35 °C, and a critical pressure of 1.67 MPa.

[0011] Perfluorohexane, with a CAS number of 355-42-0, has a molecular formula of C 6 F 14 , a molecular weight of 338.04, a standard boiling point of 57.12 °C, a critical temperature of 174.85 °C, and a critical pressure of 1.7416 MPa.

[0012] Perfluorohexanone, with a CAS number of 756-13-8, has a molecular formula of C 6 F 12 O, a molecular weight of 316.04, a standard boiling point of 49.05 °C, a critical temperature of 168.66 °C, and a critical pressure of 1.869 MPa.

[0013] Perfluoromethylcyclopentane, with a CAS number of 1805-22-7, has a molecular formula of C 6 F 12 , a molecular weight of 300.5, a standard boiling point of 48 °C, a critical temperature of 184.32 °C, and a critical pressure of 2.7155 MPa.

[0014] Table 1 Physical property parameters of substances

[0015]

[0016] The object of the present invention is achieved by the following technical solutions:

[0017] The present invention provides a liquid cooling medium, which comprises heptafluoro-2,4,4-tris(trifluoromethyl)-2-pentene.

[0018] Furthermore, the liquid cooling medium further comprises a second component selected from at least one of hexafluoropropylene dimer, hexafluoropropylene trimer, perfluorohexanone, perfluorohexane, and perfluoromethylcyclopentane, and the mass content of the second component accounts for the total amount of the liquid cooling medium by a value ≥0 and ≤90%.

[0019] Still further, the liquid cooling medium further comprises a second component selected from at least one of hexafluoropropylene dimer, hexafluoropropylene trimer, perfluorohexanone, perfluorohexane, and perfluoromethylcyclopentane, and the mass content of the second component accounts for 10-90% of the total amount of the liquid cooling medium.

[0020] Even still further, the liquid cooling medium further comprises a second component selected from at least one of hexafluoropropylene dimer, hexafluoropropylene trimer, perfluorohexanone, perfluorohexane, and perfluoromethylcyclopentane, and the mass content of the second component accounts for 40-80% of the total amount of the liquid cooling medium.

[0021] As an embodiment, the liquid cooling medium is used as a phase change liquid cooling working medium, the second component is selected from at least one of hexafluoropropylene dimer, perfluorohexanone, perfluorohexane, and perfluoromethylcyclopentane, and the mass content of the second component accounts for 40-80% of the total amount of the liquid cooling medium.

[0022] As another embodiment, the liquid cooling medium is used as a single-phase liquid cooling working medium, the second component is selected from at least one of hexafluoropropylene dimer, hexafluoropropylene trimer, and perfluorohexane, and the mass content of the second component accounts for the total amount of the liquid cooling medium by a value ≥0 and ≤80%.

[0023] The liquid cooling medium of the present invention comprises heptafluoro-2,4,4-tris(trifluoromethyl)-2-pentene, and the mass content of the heptafluoro-2,4,4-tris(trifluoromethyl)-2-pentene accounts for the total amount of the liquid cooling medium by a value >0 and ≤100%; preferably 10-90%; more preferably 20-60%.

[0024] The boiling point of the liquid cooling medium of the present invention is 50-105°C, and the dielectric constant <2.5.

[0025] The present invention also provides an application of the liquid cooling medium. The liquid cooling medium is used as a heat transfer working medium in a single-phase immersion cooling system, and the single-phase immersion cooling system includes a fluorine pump and an external side heat exchange device. The fluorine pump and the external side heat exchange device transfer heat to the environment.

[0026] The present invention also provides an application of a liquid cooling medium, where the liquid cooling medium is used as a heat transfer working fluid in a phase change immersion cooling system, and the phase change immersion cooling system includes a condensation pipeline. The condensation pipeline serves as a phase change loop of the liquid cooling medium.

[0027] The present invention also provides a data center device, including electronic circuit components and a liquid cooling medium, where at least part of the electronic circuit components are immersed in the liquid cooling medium. The electronic circuit components include server memory, CPU, printed circuit board, inductor, etc.

[0028] The present invention also provides an energy storage device, including a battery pack and a liquid cooling medium, where at least part of the battery pack is immersed in the liquid cooling medium.

[0029] The present invention also provides an electric vehicle charging pile, including an internal IGBT, an AC / DC module, a DC / DC module, and a liquid cooling medium, where at least part of the internal IGBT, AC / DC module, or DC / DC module is immersed in the liquid cooling medium.

[0030] Furthermore, the electric vehicle charging pile further includes a charging gun cable, and the charging gun cable is in indirect contact with the liquid cooling medium.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. The liquid cooling medium of the present invention has the advantages of high insulation, non-flammability, and excellent compatibility with device materials, which can ensure the safety of equipment during the immersion use of the liquid cooling medium.

[0033] 2. The liquid cooling medium of the present invention has the advantages of low viscosity and small surface tension, excellent liquid flow performance, small flow boundary layer and thermal boundary layer. The comprehensive heat transfer performance is excellent, and the required pump work is small, and the system operation cost is less.

[0034] 3. The liquid cooling medium of the present invention has a lower freezing point and can be applied in cold environments or systems with low temperature requirements.

[0035] 4. The liquid cooling medium of the present invention can achieve a boiling temperature between 50°C and 105°C through different ratios, and can respectively achieve single-phase cooling and phase change cooling to meet the cooling mode requirements of different application scenarios. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of a single-phase immersion liquid cooling system according to Application Example 1 of the present invention, where 1 - host / server; 2 - housing; 3 - air heat exchanger; 4 - fluorine pump; 5 - temperature / pressure sensor.

[0037] Figure 2 Schematic diagram of the phase change immersion liquid cooling system for Application Example 2 of the present invention. Among them, 1 - outer shell; 2 - host / server; 3 - phase change liquid cooling medium; 4 - condensate water pipeline; 5 - fan; 6 - cooling water; 7 - pressure / liquid level sensor. Specific Embodiments

[0038] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative solutions, improvement solutions, and equivalent solutions that may be included within the scope of the claims.

[0039] The components of the liquid cooling medium in Examples 1 - 6 are shown in Table 2.

[0040] The liquid cooling media in Examples 2 - 6 are physically mixed by mass percentage in the liquid state at normal temperature and pressure.

[0041] Table 2 Components of the liquid cooling medium in Examples 1 - 6 (mass percentage)

[0042]

[0043]

[0044] Comparative Example 1: Water - ethylene glycol solution (50%:50%).

[0045] Comparative Example 2: Mineral oil.

[0046] Basic physical properties of the liquid cooling medium

[0047] (I) Flammability

[0048] Table 3 shows the combustion grades of the liquid cooling media in the examples and comparative examples.

[0049] Table 3 Flammability

[0050] Example Combustion rating Example 1 Non-flammable Example 2 Non-flammable Example 3 Non-flammable Example 4 Non-flammable Example 5 Non-flammable Example 6 Non-flammable Comparative example 1 Flammable Comparative example 2 Flammable

[0051] The above flammability test adopts the national standard GB / T 261 - 2021. It can be seen from Table 3 above that the liquid cooling media of all examples of the present invention are non - flammable.

[0052] (II) Key physical property data

[0053] Table 4 shows the key physical property data of the liquid cooling media in the examples and comparative examples.

[0054] Table 4 Temperature slip, evaporation enthalpy, and environmental performance

[0055]

[0056]

[0057] As can be seen from Table 4, the viscosities of the embodiments of the present invention are much lower than those of the comparative examples, indicating that the fluidity of the embodiments is more excellent than that of the comparative examples. During the operation of the system, the required pump power is smaller, and it is easier to form turbulence to break the flow boundary layer and the thermal boundary layer, enhancing the heat transfer effect. In addition, through different ratio mixtures, the embodiments can form compositions with different boiling temperature gradients, and can respectively achieve two heat transfer modes of single-phase liquid cooling and phase change liquid cooling. Corresponding composition working fluids can be developed according to the equipment requirements of different industries.

[0058] Safety of the materials of the liquid cooling medium equipment

[0059] The safety of the liquid cooling system equipment depends on the compatibility between the liquid cooling medium and the equipment materials.

[0060] The evaluation of compatibility with various materials is carried out by the following method: Take 100 mL of the liquid cooling medium of Examples 1-6 and add it to a hydration reaction kettle. Put the relevant material slices respectively and place them at 100 °C for 500 h of long-term contact. After the end, take out the liquid cooling medium and the material slices and test the compatibility situation.

[0061] Table 5 Mass changes of each material before and after

[0062]

[0063] Table 6 Volume changes of each material before and after

[0064]

[0065]

[0066] Table 7 Composition changes of the liquid cooling working fluid

[0067]

[0068] As can be seen from Tables 5-7, the compatibility performance between the embodiments and the materials is excellent. The change rates of the mass and volume of the materials themselves under long-term high-temperature contact do not exceed ±1.5%, and there are no incompatible phenomena such as obvious expansion, deformation, softening, and fading in the material properties. The change rate of the composition of the liquid cooling working fluid itself does not exceed ±1%, all within the required index range.

[0069] The liquid cooling medium is used for equipment

[0070] Application Example 1:

[0071] The desktop computer host is designed as a closed immersion single-phase liquid cooling structure. There is cooling liquid inside the host, heat dissipation fins are installed on the surface of the CPU, and all components of the computer host are immersed in the cooling liquid. At the same time, a small fluorinated liquid pump is installed inside. There are a fan and a cooling liquid heat dissipation pipeline on the top of the host. The cooling liquid is driven by the pump to flow through the surface of the computer host components to take away heat, and then enters the heat dissipation pipeline to discharge the heat into the environment and then re-enters the computer host to absorb heat.

[0072] The liquid cooling media of Example 1, Example 3, and Example 5 are respectively poured into the host. At the same time, the AID64 System Stability Test software is run for the CPU to operate at full load (burn-in), and the temperature is detected through the AID64 program. Under the condition of the CPU operating at full load, the computer runs continuously and stably for 60 days respectively. The temperatures of the upper-layer liquid cooling medium, the bottom-layer liquid cooling medium, the inlet liquid medium of the cooling circuit, the outlet liquid medium of the cooling circuit, and the CPU core are shown in Table 8. During the operation process, all components inside the host operate normally, and no appearance or functional changes occur. It can meet the cooling requirements for the long-term full-load operation of the computer host CPU.

[0073] Table 8 Temperatures at various points of the single-phase immersion computer host

[0074] Example Bottom layer of the device Upper layer of the device Cooling circuit inlet Cooling circuit outlet CPU Example 1 28 32 31.7 27.3 62 Example 3 27.6 32.1 31.7 27 63 Example 5 28.2 33.5 33.2 27.8 63

[0075] Table 9 Configuration parameters of the desktop computer host in Application Example 1

[0076] Fittings Motherboard CPU Memory Graphics card Main hard drive Model Gigabyte H510MH Intel Core i5 10400 ADATA DDR4 UHD 630 SNVS2000G

[0077] Application Example 2:

[0078] The same computer configuration and device layout structure as in Application Example 1 are adopted. Heat dissipation fins are not loaded on the surface of the CPU, and there is no fluorinated liquid pump involved inside the host. Heat transfer is carried out through the phase change of the cooling liquid on the heating surface. There is a condensed water circuit on the top of the host. The fluorinated liquid absorbs heat on the heating surface and changes from liquid to gas, and then condenses into liquid outside the condensed water pipe on the top of the host and falls back to the internal area of the host.

[0079] The external display of the computer host. The liquid cooling media of Example 2, Example 4, and Example 6 were respectively filled into the host, and the AID64 System Stability Test software was run simultaneously to perform full-load operation of the CPU (burn-in), and the temperature was detected through the AID64 program. Under the condition of full-load operation of the CPU, the computer ran continuously and stably for 60 days respectively. The temperatures of the upper-layer liquid cooling medium of the host, the bottom liquid cooling medium of the host, the inlet water of the condenser tube, the outlet water of the condenser tube, and the CPU core are shown in Table 10. During the operation, all components inside the host operated normally without any appearance or functional changes. It can meet the cooling requirements for the long-term full-load operation of the CPU of the computer host.

[0080] Table 10 Temperatures at various points of the phase-change computer host

[0081] Example Bottom layer of the device Upper layer of the device Condenser inlet Condenser outlet CPU Example 2 40.5 45 31.5 31.9 82 Example 4 42.3 50.2 31.7 32.2 82 Example 6 40.2 50.3 31.5 32 81

[0082] Application of Comparative Example 1:

[0083] A desktop computer with the same configuration as Application Example 1 was used. An ordinary fan was used to exchange heat for the CPU, and the AID64 System Stability Test software was run simultaneously to perform full-load operation of the CPU (burn-in), and the temperature was detected through the AID64 program. It was shown that when the CPU core temperature exceeded 100 °C, an alarm was triggered, and the CPU automatically reduced its operating load to start self-protection. This indicates that in the natural air-cooling scenario, the air-cooling mode cannot meet the high-load operation of the CPU.

[0084] The content described in this specification is only a list of the implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments.

Claims

1. A liquid cooling medium, characterized in that: the liquid cooling medium contains heptafluoro-2,4,4-tris(trifluoromethyl)-2-pentene.

2. The liquid cooling medium according to claim 1, characterized in that: the liquid cooling medium further contains a second component, the second component is selected from at least one of hexafluoropropylene dimer, hexafluoropropylene trimer, perfluoropentanone, perfluorohexane, perfluoromethylcyclopentane, and the mass content of the second component accounts for the total amount of the liquid cooling medium ≥0 and ≤90%.

3. The liquid cooling medium according to claim 2, characterized in that: the second component is selected from at least one of hexafluoropropylene dimer, perfluoropentanone, perfluorohexane, perfluoromethylcyclopentane, and the mass content of the second component accounts for 40-80% of the total amount of the liquid cooling medium.

4. The liquid cooling medium according to claim 2, characterized in that: the second component is selected from at least one of hexafluoropropylene dimer, hexafluoropropylene trimer, perfluorohexane, and the mass content of the second component accounts for the total amount of the liquid cooling medium ≥0 and ≤80%.

5. The liquid cooling medium according to any one of claims 1-4, characterized in that: the boiling point of the liquid cooling medium is 50-105°C, and the dielectric constant <2.

5.

6. An application of the liquid cooling medium according to any one of claims 1-5, characterized in that: the liquid cooling medium is used as a heat transfer working medium in a single-phase immersion cooling system, and the single-phase immersion cooling system includes a fluorine pump and an external side heat exchange device.

7. An application of the liquid cooling medium according to any one of claims 1-5, characterized in that: the liquid cooling medium is used as a heat transfer working medium in a phase change immersion cooling system, and the phase change immersion cooling system includes a condensation pipeline.

8. A data center device, including electronic circuit components and a liquid cooling medium, characterized in that: the liquid cooling medium is the liquid cooling medium according to any one of claims 1-5, and at least part of the electronic circuit components are immersed in the liquid cooling medium.

9. An energy storage device, including a battery pack and a liquid cooling medium, characterized in that: the liquid cooling medium is the liquid cooling medium according to any one of claims 1-5, and at least part of the battery pack is immersed in the liquid cooling medium.

10. An electric vehicle charging pile, including an internal IGBT, an AC / DC module, a DC / DC module and a liquid cooling medium, characterized in that: the liquid cooling medium is the liquid cooling medium according to any one of claims 1-5, and at least part of the internal IGBT, AC / DC module or DC / DC module is immersed in the liquid cooling medium.

11. The electric vehicle charging pile according to claim 10, characterized in that: the electric vehicle charging pile further includes a charging gun cable, and the charging gun cable is in indirect contact with the liquid cooling medium.

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