Direct contact immersed cooling liquid and application and thermal management device thereof

Abstract

The invention provides a direct contact immersed cooling liquid, application thereof and a thermal management device, and the direct contact immersed cooling liquid comprises, by mass, 70-95% of a component A and 5-30% of a component B, the boiling point of the component A is more than or equal to 100 DEG C, and the component B is a non-combustible substance with the boiling point of-20 to 38 DEG C; the non-combustible substance comprises a fluorine-containing compound with a chemical general formula of CmHnFxClyOz, and the value of m in the CmHnFxClyOz is 1-6; n has a value of 0 to 6; x has a value of 0 to 8; y has a value of 0 to 6; and z has a value of 0-4. According to the cooling liquid provided by the invention, the energy storage device is directly cooled through phase change heat absorption, meanwhile, the risk that the component B escapes and leaks is reduced due to the existence of the component A, and the cooling safety is improved. In addition, the cooling liquid in the energy storage device is in direct contact with the battery cell, the energy storage battery is directly cooled through phase change heat absorption, and rapid heat exchange of the battery cell in the energy storage device is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of battery thermal management, and in particular to a direct contact immersion coolant and its application and thermal management device. Background Art

[0002] At present, temperature is an important factor affecting the safe operation of lithium (sodium) ion batteries. For lithium (sodium) ion batteries, the operating temperature and temperature consistency have a great impact on their efficiency, life and safety. In a high temperature environment, the attenuation rate of lithium (sodium) batteries will be accelerated, the cycle life of the battery will be reduced, and in severe cases, thermal runaway will cause safety accidents; in a low temperature environment, it will also affect the battery life and induce safety risks. For example, high-rate charging at low temperature is prone to the formation of lithium dendrites; in addition, the inconsistency of battery temperature will also directly lead to a reduction in the service life of the system.

[0003] Currently, the most common battery energy storage system is container-type, and its common heat dissipation technologies include air cooling, liquid cooling and immersion cooling. Among them, air cooling and liquid cooling have obvious disadvantages, the actual operating temperature rises, and the temperature difference is large; while immersion cooling includes two modes: the coolant is in a flowing state and a stationary state inside the battery pack; when the coolant is in a flowing state inside the battery pack, a large circulation volume of coolant is required for heat exchange, and at the same time, the fluid distribution requirements of the coolant are high; when the coolant is in a stationary state inside the battery pack, the cooling effect on the battery cell is limited. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. The present application proposes a direct contact immersion coolant and its application and thermal management device, which can utilize the large heat absorption of the coolant gas-liquid phase change to directly cool the energy storage device through phase change heat absorption. At the same time, the presence of component A can reduce the risk of component B escaping and leaking, thereby improving cooling safety. In addition, in the energy storage device of the present application, the coolant is in direct contact with the battery cell and directly cools the energy storage battery through phase change heat absorption, so that the battery cell in the energy storage device can quickly exchange heat, allowing it to operate (charge and discharge) under constant temperature conditions, greatly extending the life and safety of the energy storage device.

[0005] According to an embodiment of the present application, a direct contact immersion coolant is proposed. Taking the coolant as a reference, the coolant comprises a component A of 70-95% by mass and a component B of 5-30% by mass; the boiling point of the component A is ≥100°C and the component B is a non-combustible substance with a boiling point of -20-38°C; the non-combustible substance comprises a chemical formula of C m H n F x Cl y O z Fluorinated compounds, C m Hn F x Cl y O z The value of m is 1-6; the value of n is 0-6; the value of x is 0-8; the value of y is 0-6; and the value of z is 0-4.

[0006] In some embodiments, the fluorine-containing compound is a fluoroketone compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m+1 is equal to the value of n+x+y+z; And / or, the fluorine-containing compound is perfluoropentanone.

[0007] In some embodiments, the fluorine-containing compound is an alkane compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m+2 is equal to the value of n+x+y+z and the value of z is 0; And / or, the fluorine-containing compound is monofluorodichloroethane, 1%, 1-difluoro-1-chloroethane, trifluorodichloroethane, pentafluoropropane, pentafluorobutane or perfluoro-n-pentane.

[0008] In some embodiments, the fluorine-containing compound is a cycloalkane compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m is equal to the value of n+x+y+z and the value of z is 0; And / or, the fluorine-containing compound is octafluorocyclobutane.

[0009] In some embodiments, the fluorine-containing compound is an olefin compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m is equal to the value of n+x+y+z and the value of z is 0; And / or, the fluorine-containing compound is chlorotrifluoropropene.

[0010] In some embodiments, the component A is selected from at least one of mineral oil, macromolecular hydrocarbon oil, silicone oil or fluorinated liquid.

[0011] The coolant in the present application is a liquid with low dielectric constant and non-conductive, which has the characteristics of large heat absorption during liquid phase change. The coolant can cool the battery cell by evaporating into steam to absorb heat and remove the heat of the battery cell, and the steam is condensed into liquid to be recycled as coolant. The coolant in the present application includes component A and component B; the presence of component A reduces the content of component B, thereby reducing the risk of escape and leakage of component B and improving cooling safety.

[0012] In the related technologies, the cooling technologies of air cooling and liquid cooling both utilize temperature difference to achieve heat exchange. There is no phase change in the heat exchange process, only an increase or decrease in temperature. However, the phase change process of the coolant in the present application has almost no temperature change. Due to the particularity of the battery, the coolant must be non-combustible and the boiling point must not exceed 38°C under standard atmospheric pressure. Therefore, the coolant in the present application has the characteristics of low boiling point, easy volatility, flame retardancy, safety and environmental protection.

[0013] According to a second aspect of the present application, it is proposed that the coolant described in any of the above embodiments is used in direct full immersion phase change cooling of an energy storage device.

[0014] In some embodiments, the battery cells of the energy storage device are completely immersed in the coolant, and the coolant absorbs the heat of the battery cells to generate steam. The steam exchanges heat with an external refrigerant and condenses into the coolant, and the cycle repeats.

[0015] Among them, in the present application, the coolant described in any of the above embodiments is applied in the direct full immersion phase change cooling of the energy storage device, by immersing all the battery cells of the energy storage device in the coolant, utilizing the small thermal resistance, fast heat conduction and large heat exchange area of ​​direct contact between the coolant and the battery cell, and utilizing the heat generated by the normal operation of the battery cell to be vaporized and absorbed by the coolant, and the temperature of the battery cell is controlled to be basically constant, and the generated steam exchanges heat with the external refrigerant and condenses into the coolant, and then continues to vaporize and absorb heat, and so on and so forth, to ensure that the temperature of the battery cell is constant at a certain value (the specific value depends on the use requirements, and can be adjusted by the coolant composition and the control of the pressure of the energy storage device, usually the working temperature of the battery cell is 10-40°C, and the working pressure of the energy storage device is 20-300KPa (absolute pressure)).

[0016] In addition, in the present application, the coolant absorbs heat from the battery through phase change. The latent heat of phase change of the material is much greater than the sensible heat, with a high heat transfer coefficient, a fast cooling speed, and a high cooling efficiency. When the coolant produces bubbles during the vaporization process at the hot spot, the floating of the bubbles automatically disturbs the liquid, thereby enhancing heat exchange and achieving good temperature control effect for the battery.

[0017] According to a third aspect of the present application, a thermal management device is proposed, comprising the coolant described in any one of the above embodiments.

[0018] In some embodiments, the thermal management device further includes an immersion box, electronic components disposed in and in direct contact with the cooling liquid, and a heat exchange device connected to the immersion box for heat exchange; a gas phase space is also retained in the immersion box.

[0019] In the embodiment of the present application, the thermal management device includes an immersion box, a coolant, electronic components in direct contact with the coolant, and a heat exchange device. In addition, a gas phase space is retained in the immersion box. When the thermal management device is used normally, the air in the gas phase space needs to be removed (to reduce non-condensable gases). The gas phase space is almost entirely filled with low-boiling vapor. At the same time, the coolant isolates the electronic components from the gas phase space. If the electronic components are damaged and release combustibles, a liquid isolation layer can be quickly formed to improve safety.

[0020] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 is a schematic structural diagram of a thermal management device provided in one embodiment of the present application; In the figure, 1. Immersed box; 2. Electronic components; 3. Gas phase space; 4. Cooling liquid; 5. Heat exchange device. DETAILED DESCRIPTION

[0022] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limiting the present application. On the contrary, the present application includes all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0023] Among them, the electrochemical energy storage industry is developing rapidly, and the safety of lithium (sodium) ion battery energy storage applications still faces huge challenges. Among them, temperature is an important factor affecting the safe operation of lithium (sodium) ion batteries. Reasonable temperature range and temperature distribution consistency are key parameters to ensure the safety and long life of large-scale battery energy storage systems.

[0024] For lithium (sodium) ion batteries, the operating temperature and temperature consistency have a great impact on their efficiency, life and safety. The temperature range that lithium (sodium) batteries can withstand is -40-60℃, and the optimal operating temperature range is 10-35℃. In a high temperature environment, the attenuation rate of lithium (sodium) batteries will be accelerated, the cycle life of the battery will be reduced, and in severe cases, thermal runaway will occur, causing safety accidents; in a low temperature environment, it will also affect the battery life and induce safety risks. For example, low-temperature high-rate charging is prone to cause the formation of lithium dendrites; in addition, the inconsistency of battery temperature will also directly lead to a reduction in the service life of the system. The research results of the China Electric Power Research Institute show that when the temperature difference in the battery module reaches 5℃, the life of the battery module is reduced by 30% compared with the life of the module with a temperature difference of less than 2℃. Relevant research reports show that a maximum temperature difference of more than 5℃ will form hot spots inside the lithium-ion battery, seriously affecting the safety and life of the battery. Reasonable thermal management can ensure that the battery operating temperature is within an appropriate range and improve the working environment of the battery, which plays an important role and significance in improving battery life, efficiency and system safety and economy.

[0025] Currently, the most common battery energy storage system is container-type, with several lithium (sodium) ion batteries forming modules, and sensors usually monitoring voltage and temperature in the modules. Several modules are placed in a rack, and the rack is then installed in the energy storage box, in which a thermal management system needs to be installed. The energy storage thermal management system is an important means to reduce the risk of thermal runaway of batteries. Among them, battery energy storage temperature monitoring and thermal control are the main functions of the thermal management system. Currently common heat dissipation technologies include air cooling, liquid cooling, and immersion cooling.

[0026] The advantages of air cooling are relatively simple system design, low cost, easy implementation and maintenance, and high reliability. Its disadvantages are also obvious: low specific heat capacity, small thermal conductivity, not suitable for high-power scenarios, low heat dissipation efficiency, greatly affected by ambient temperature, and forced air cooling generates a lot of noise. The actual operating temperature rises and the temperature difference is large; the advantages of the liquid cooling system are higher specific heat capacity, mass flow, faster heat transfer speed; it has a better cooling effect and can achieve uniform temperature distribution. Its disadvantages are complex layout, more components, large system mass, high cost and poor reliability, requiring high sealing, and there is a risk of liquid leakage. The actual operating temperature rises (better than air cooling) and the temperature difference is large (better than air cooling).

[0027] The immersion heat dissipation system achieves the purpose of cooling by immersing the entire battery in the coolant. In one mode, the coolant is in a flowing state inside the battery pack, and the coolant is cooled by an external heat exchanger, and then the battery cell is cooled by the coolant; in another mode, the coolant is stationary, and there is a cold plate (heat exchange component) at the bottom of the battery pack, and the battery cell and coolant are cooled by the cold plate. In the first mode, because the coolant has a small heat capacity and a small single heat absorption, a large circulation volume of coolant is required for heat exchange, and the fluid distribution of the coolant is required to be high. In the second mode, due to the influence of the physical properties of the coolant such as heat capacity and thermal conductivity, the cooling effect of the battery cell is limited, and the battery cell is mainly cooled by the bottom cold plate.

[0028] One type of existing technical solution is to exchange heat with the refrigerant in the heat exchanger through external circulation, and the other type is to rely on the bottom cold plate to cool the battery cell and immersion liquid. Due to the low thermal conductivity and small heat capacity of the immersion liquid, it is not possible to achieve good temperature control. For example, the relevant technology provides that by selecting halogenated hydrocarbons with a carbon number of 2-4 and insulating cooling oil, the battery immersion coolant obtained has the advantages of good flame retardancy, high insulation, low-temperature fluidity, heat transfer performance, etc., which can effectively inhibit the occurrence of battery thermal runaway and reduce the harm caused by battery thermal runaway. The mass fraction of the flame retardant in the relevant technology is required to be 30-60% (halogenated hydrocarbons with a carbon number of 2-4 are selected), and the small molecular substances have a relatively low boiling point and are easy to volatilize or decompose at high temperature, releasing a large amount of halogen flame retardant elements, quenching the combustion factor, and achieving the effect of efficient flame retardancy. Halogenated hydrocarbons (containing chlorine or bromine) with 2-4 carbon atoms have a low boiling point and are easy to escape into the atmosphere, causing damage to the ozone layer (in the stratosphere, strong ultraviolet radiation causes photodissociation of chlorofluorocarbons or bromine-containing compound molecules, releasing highly active atomic chlorine and bromine. Atomic chlorine and bromine free radicals are key substances for destroying the ozone layer). In addition, in the related technology, the halogenated hydrocarbons in the coolant play a major flame retardant role, which uses sensible temperature difference for heat exchange, and also has disadvantages such as poor temperature consistency and large temperature rise.

[0029] Therefore, in the existing immersion energy storage liquid cooling system, the coolant is the core of the battery thermal management system, and its thermophysical properties largely determine the operating performance of the battery system. In the immersion phase change liquid cooling system, if there is a gas leak, the low-boiling substances in the coolant will escape, which may eventually lead to the release of all low-boiling substances into the atmosphere. In order to reduce the impact of low-boiling substances on the environment in extreme cases. Low-boiling substances are mixed with the second type of coolant to reduce the amount of low-boiling substances in the vapor-liquid phase change coolant. The second type of coolant is required to be a liquid with a boiling point ≥100°C (under standard atmospheric pressure). The second type of coolant is a coolant commonly used in immersion thermal management systems at home and abroad. There are mainly three categories: fluorinated liquid, hydrocarbons, and silicone oils. Fluorinated liquid, hydrocarbons, and silicone oil coolants all have good insulation properties, but when used as single-phase immersion coolants, the heat dissipation performance is poor. It is difficult to effectively control the temperature of the battery cell within a small range when used alone, and the temperature difference between the battery cells is large.

[0030] The coolant in the scope of this application includes component A with a mass fraction of 70-95% and component B with a mass fraction of 5-30%. Component B is a non-combustible substance with a boiling point of -20-38°C. It is a key core raw material in the coolant. It undergoes phase change (gasification and condensation process) during use. The temperature of the battery core is controlled to be constant through the vaporization of component B, which is then condensed in the condenser to form a liquid that flows back into the energy storage battery box and circulates repeatedly. In addition, component B is mainly a refrigerant transfer medium in this process, and also has a flame retardant effect.

[0031] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0033] To achieve the above-mentioned purpose, according to the embodiment of the present application, a direct contact immersion coolant is proposed, which comprises a component A of 70-95% by mass and a component B of 5-30% by mass, based on the coolant; the boiling point of component A is ≥100°C and component B is a non-combustible substance with a boiling point of -20-38°C; the non-combustible substance comprises a chemical formula of C m H n F x Cl y O z Fluorinated compounds, C m H n F x Cl y O z The value of m is 1-6; the value of n is 0-6; the value of x is 0-8; the value of y is 0-6; and the value of z is 0-4.

[0034] Among them, the embodiment of the present application includes component A and component B; wherein, based on the coolant, the mass fraction of component A is 70-95% and the mass fraction of component B is 5-30%, wherein the boiling point of component A is ≥100°C; component B is a non-combustible substance with a boiling point of -20-38°C.

[0035] For example, the mass fraction of component A is 70%, 71%, 74%, 75%, 76%, 77%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 90%, 91%, 92%, 95%, etc., and the component A is selected from at least one of mineral oil, macromolecular hydrocarbon oil, silicone oil or fluorinated liquid, for example, mineral oil includes No. 10 transformer oil, No. 25 transformer oil, No. 45 transformer oil, paraffin oil, etc., macromolecular hydrocarbon oil includes poly-α-olefin, etc. Silicone oil includes oligomeric dimethyl siloxane, etc.; fluorinated liquid includes hexafluoropropylene trimer, hydrofluoroether, perfluoropolyether, etc. Mineral oil is a liquid hydrocarbon mixture obtained by refining petroleum, and its main components include straight-chain, branched-chain alkanes and alkyl-substituted cycloalkanes; macromolecular hydrocarbon oil refers to a heavy oil component composed of compounds such as long-chain alkanes, cycloalkanes and aromatic hydrocarbons with carbon atoms above C15; silicone oil is a polysiloxane formed by alternating silicon and oxygen elements.

[0036] The mass fraction of component B is 5%, 9%, 10%, 11%, 14%, 15%, 16%, 20%, 21%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc. When the mass fraction of component B is too small, such as less than 5%, because it is the core material of phase change heat transfer, when it is applied to the thermal management device, it is easy to cause uneven distribution of various regions of the thermal management device, which is equivalent to invalid filling. When the mass fraction of component B is too large, such as greater than 30%, it is necessary to consider strict sealing in the design of the thermal management device. Therefore, within the scope of this application, the immersion coolant and its application have better effect and economy.

[0037] The boiling point of the non-combustible substance in component B is -20-38°C under standard atmospheric pressure. For example, under standard atmospheric pressure, the boiling point of the non-combustible substance is -20°C, -10°C, 0°C, 10°C, 20°C, 30°C, 38°C, etc. The non-combustible substance in this embodiment includes a fluorine-containing compound, and the chemical formula of the fluorine-containing compound is C m H n F x Cl y O z ; where the value of m is 1-6; the value of n is 0-6; the value of x is 0-8; the value of y is 0-6; and the value of z is 0-4.

[0038] For example, the chemical formula is C m H n F x Cl y O z In the fluorine-containing compound, the value of m is 1, 2, 3, 4, 5 or 6, etc.; the value of n is 0, 1, 2, 3, 4, 5 or 6, etc.; the value of x is 0, 1, 2, 3, 4, 5, 6, 7 or 8, etc.; the value of y is 1, 2, 3, 4, 5 or 6, etc.; the value of z is 0, 1, 2, 3 or 4, etc. For example, in some embodiments, the fluorine-containing compound includes at least one of monofluorodichloroethane, perfluoropentane, pentafluoropropane or perfluoropentanone.

[0039] In some embodiments, the fluorine-containing compound is a fluoroketone compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m+1 is equal to the value of n+x+y+z. In this embodiment, the fluoroketone compound can be exemplified by perfluoropentanone (C5F 10 O) etc.

[0040] In some embodiments, the fluorine-containing compound is an alkane compound, wherein the chemical formula C m H n F x Cly O z The value of 2m+2 is equal to the value of n+x+y+z and the value of z is 0; in this embodiment, the alkane compound can be exemplified by dichloromonofluoroethane (CCl2FCH3), dichlorodifluoroethane (C2H3ClF2), dichlorotrifluoroethane (CF3CHCl2), pentafluoropropane (C3H3F5), pentafluorobutane (C4H5F5) or perfluoropentane (C5F 12 ) etc. In addition, when the fluorine-containing compound is a cycloalkane compound, the chemical formula C m H n F x Cl y O z The value of 2m is equal to the value of n+x+y+z and the value of z is 0; at this time, the cycloalkane compound can be octafluorocyclobutane (C4F8).

[0041] In some embodiments, the fluorine-containing compound is an olefin compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m is equal to the value of n+x+y+z and the value of z is 0; in this embodiment, the olefin compound may be chlorotrifluoropropylene (C3H2ClF3).

[0042] The coolant in the present application is a liquid with low dielectric constant and non-conductive properties, and has the characteristics of low boiling point, high volatility, flame retardancy, safety and environmental protection. There is almost no temperature change in the phase change process of the coolant in the present application. Due to the particularity of the battery, the coolant must be non-combustible, and the boiling point does not exceed 38°C under standard atmospheric pressure. Therefore, the coolant in the present application has the characteristics of low boiling point, high volatility, flame retardancy, safety and environmental protection.

[0043] According to a second aspect of the present application, it is proposed that the coolant in any of the above embodiments is used in direct full immersion phase change cooling of an energy storage device.

[0044] In some embodiments, the battery cells of the energy storage device are completely immersed in a coolant, and the coolant absorbs the heat of the battery cells to generate steam. The steam exchanges heat with an external refrigerant and condenses into a coolant, and the cycle repeats.

[0045] Among them, in the present application, the coolant in any of the above embodiments is applied in the direct full immersion phase change cooling of the energy storage device, by immersing all the battery cells of the energy storage device in the coolant, utilizing the small thermal resistance, fast heat conduction and large heat exchange area of ​​direct contact between the coolant and the battery cell, and utilizing the heat generated by the normal operation of the battery cell to be vaporized and absorbed by the coolant, and the temperature of the battery cell is controlled to be basically constant, and the generated steam exchanges heat with the external refrigerant and condenses into the coolant, and then continues to vaporize and absorb heat, and so on and so forth, to ensure that the temperature of the battery cell is constant at a certain value (the specific value depends on the use requirements, and can be adjusted by the coolant composition and the control of the pressure of the energy storage device. Usually, the working temperature of the battery cell is 10-40°C, and the working pressure of the energy storage device is 20-300KPa (absolute pressure)).

[0046] In addition, in the present application, the coolant absorbs heat from the battery through phase change. The latent heat of phase change of the material is much greater than the sensible heat, with a high heat transfer coefficient, a fast cooling speed, and a high cooling efficiency. When the coolant produces bubbles during the vaporization process at the hot spot, the floating of the bubbles automatically disturbs the liquid, thereby enhancing heat exchange and achieving good temperature control effect for the battery.

[0047] According to a third aspect of the present application, a thermal management device is proposed, comprising the coolant 4 in any one of the above embodiments.

[0048] In some embodiments, the thermal management device further includes an immersion box 1, electronic components 2 disposed in and in direct contact with the coolant 4, and a heat exchange device 5 connected to the immersion box 1 for heat exchange; a gas phase space 3 is also retained in the immersion box 1.

[0049] For example Figure 1 As shown, the thermal management device includes an immersion box 1, wherein the immersion box 1 is a fully enclosed box, and an electronic component 2 is arranged in the box, wherein the electronic component 2 can be a battery cell, etc., and then the coolant 4 in any of the above embodiments is injected into the box, wherein the liquid level of the coolant 4 is above the electronic component 2, and there is a gas phase space 3 between the liquid level of the coolant 4 and the top of the box. In addition, an air outlet and a liquid inlet are provided on the box, wherein the air outlet and the liquid inlet are respectively connected to the hot side of the heat exchange device 5, and the cold side of the heat exchange device 5 is introduced into the external refrigerant to condense the steam on the hot side of the heat exchange device 5. When the thermal management device is used normally, the air in the gas phase space 3 needs to be removed (to reduce non-condensable gas), and the gas phase space 3 is almost entirely steam of low-boiling substances. At the same time, the coolant 4 isolates the gas phase space 3 of the electronic component 2. If the electronic component 2 is damaged and releases combustibles, a liquid isolation layer can be quickly formed to improve safety.

[0050] Therefore, the thermal management device provided in this embodiment directly cools the electronic components by absorbing heat through phase change of the coolant, thereby achieving rapid heat exchange of the electronic components and allowing them to operate (charge and discharge) under constant temperature conditions, greatly extending the life of the electronic components and improving the safety of the use of the electronic components.

[0051] To facilitate further understanding of the present application, the scheme of the present application is further described below in conjunction with the embodiments. Those skilled in the art will understand that the description in the present application is only part of the examples, and any other suitable specific examples are within the scope of the present application.

[0052] Example 1 This embodiment provides a direct contact immersion coolant, and the preparation steps are as follows: Component A is selected from No. 25 transformer insulation cooling oil, which has a weight ratio of 80 parts, and component B is selected from monofluorodichloroethane, which has a weight ratio of 20 parts. Component A and component B are blended to obtain a direct contact immersion coolant.

[0053] Example 2 This embodiment provides a direct contact immersion coolant, which is made by the following method: component A is selected from polyalphaolefin (PAO 2.5%) with a weight portion of 90 parts, component B is selected from perfluoropentanone with a weight portion of 10 parts, and component A and component B are blended to obtain a direct contact immersion coolant.

[0054] Example 3 This embodiment provides a direct contact immersion coolant, which is made by the following method: Component A is selected from oligomeric dimethylsiloxane, with a weight portion of 76 parts, and component B is selected from perfluoropentanone, with a weight portion of 24 parts. Component A and component B are blended to obtain a direct contact immersion coolant.

[0055] Example 4 This embodiment provides a direct contact immersion coolant, which is made by the following method: component A is selected from hexafluoropropylene trimer, with a weight portion of 95 parts, and component B is selected from pentafluorobutane, with a weight portion of 5 parts. Component A and component B are blended to obtain a direct contact immersion coolant.

[0056] Example 5 This embodiment provides a direct contact immersion coolant, which is made by the following method: component A is selected from hexafluoropropylene trimer, with a weight portion of 93 parts, and component B is selected from pentafluoropropane with a weight portion of 7 parts. Component A and component B are blended to obtain a direct contact immersion coolant.

[0057] Example 6 The present embodiment provides a direct contact immersion coolant, which is prepared by the following method: component A is selected from 30 parts by weight of No. 25 transformer oil and 50 parts by weight of No. 45 transformer oil, and component B is selected from 10 parts by weight of monofluorodichloroethane and 10 parts by weight of perfluoropentanone; component A and component B are blended to obtain the direct contact immersion coolant.

[0058] Comparative Example Comparative experiments were conducted using commercially available No. 25 transformer insulation cooling oil, poly-α-olefin (PAO 2.5%), polydimethylsiloxane, and perfluoropolyether as coolants to form Comparative Examples 1 to 4.

[0059] Experimental example The coolant of each embodiment and comparative example was subjected to a charge and discharge performance test, wherein the charge and discharge performance test method is as follows: 48 lithium iron phosphate batteries (rated capacity 280Ah, rated voltage 3.2V) were placed in a battery pack box in series arrangement, cooling plates were set on the upper and lower sides, and NTC thermistors were set on the top terminals of the 48 battery cells in the center of the side for temperature collection. The upper and lower cold plates were connected to a constant temperature water bath, and the temperature of the cooling water entering the cold plate was controlled to be 20°C. After the setting was completed, 0.5P was continuously charged and discharged, and the temperature change of the battery cells in different media was observed. The performance of the coolant of each embodiment and comparative example is shown in Table 1.

[0060] Table 1 Coolant test table of each embodiment and comparative example

[0061] It can be seen from the data in Table 1 that the temperature rise of the lithium-ion battery in the coolant of Examples 1 to 6 is smaller, and the temperature difference between the battery cells is smaller, which can ensure the consistency of the use environment, extend the service life of the battery cells, and has good application prospects.

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0063] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A direct contact immersion coolant, characterized in that: Based on the coolant, it includes 70-95% by mass of component A and 5-30% by mass of component B; the boiling point of component A is ≥100°C and the component B is a non-combustible substance with a boiling point of -20-38°C; the non-combustible substance includes a chemical formula of C m H n F x Cl y O z Fluorinated compounds, C m H n F x Cl y O z The value of m is 1-6; the value of n is 0-6; the value of x is 0-8; the value of y is 0-6; and the value of z is 0-4.

2. The coolant according to claim 1, characterized in that: The fluorine-containing compound is a fluoroketone compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m+1 is equal to the value of n+x+y+z; And / or, the fluorine-containing compound is perfluoropentanone.

3. The coolant according to claim 1, characterized in that: The fluorine-containing compound is an alkane compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m+2 is equal to the value of n+x+y+z and the value of z is 0; And / or, the fluorine-containing compound is dichloromonofluoroethane, difluoro-1-chloroethane, dichlorotrifluoroethane, pentafluoropropane, pentafluorobutane or perfluoro-n-pentane.

4. The coolant according to claim 1, characterized in that: The fluorine-containing compound is a cycloalkane compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m is equal to the value of n+x+y+z and the value of z is 0; And / or, the fluorine-containing compound is octafluorocyclobutane.

5. The coolant according to claim 1, characterized in that: The fluorine-containing compound is an olefin compound, wherein the chemical formula C m H n F x Cl y O z The value of 2m is equal to the value of n+x+y+z and the value of z is 0; And / or, the fluorine-containing compound is chlorotrifluoropropene.

6. The coolant according to any one of claims 1 to 5, characterized in that: The component A is selected from at least one of mineral oil, macromolecular hydrocarbon oil, silicone oil or fluorinated liquid.

7. The coolant according to any one of claims 1 to 6 is used in direct full immersion phase change cooling of an energy storage device.

8. The use according to claim 7, characterized in that: The battery cells of the energy storage device are completely immersed in the coolant, and the coolant absorbs the heat of the battery cells to generate steam. The steam exchanges heat with an external refrigerant and condenses into the coolant, which is circulated repeatedly.

9. A thermal management device, characterized in that: The cooling liquid comprises the cooling liquid as claimed in any one of claims 1 to 6.

10. The thermal management device according to claim 9, characterized in that: It also includes an immersion box, electronic components arranged in and in direct contact with the cooling liquid, and a heat exchange device connected to the immersion box for heat exchange, and a gas phase space is retained in the immersion box.

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