Organic heat transfer systems, methods, and fluids

Abstract

The disclosed technology relates to a dielectric oil-based heat transfer system, method, and fluid that includes: a) a non-conductive, non-aqueous, and water-immiscible dielectric oil-based fluid; and b) at least one high molecular weight. Specifically, the technology relates to a dielectric oil-based heat transfer system, method, and fluid that has low electrical conductivity, low shear viscosity, and low flammability and provides temperature reduction in heat transfer systems, such as those for cooling battery packs or power systems of electric vehicles.

Description

[Technical Field]

[0001] The disclosed technology relates to a heat transfer system and a heat transfer method using a dielectric oil heat transfer fluid. Specifically, the technology relates to a dielectric oil heat transfer fluid having low electrical conductivity and low flammability that provides peak temperature reduction in a heat transfer system, such as for cooling battery packs or power systems of electric vehicles. [Background technology]

[0002] The operation of a power supply generates heat. A heat transfer system in communication with the power supply regulates the generated heat and ensures that the power supply operates at an optimal temperature. Heat transfer systems generally include a heat transfer fluid that facilitates the absorption and dissipation of heat from the power supply. Heat transfer fluids, generally consisting of water and glycol, can be expensive and prone to freezing. Conventional heat transfer fluids can also exhibit extremely high conductivity, often in the range of 3000 microsiemens / cm (μS / cm) or more. This high conductivity can adversely affect the heat transfer system by accelerating the corrosion of metal components, and in power supplies where the heat transfer system is exposed to electric current, such as fuel cells, high conductivity can lead to short circuits and electric shocks.

[0003] Current battery pack designs include an integrated, insulated cooling system that distributes coolant throughout the entire enclosure. When functioning correctly, the coolant from the cooling system does not come into contact with internally protected potentials. Occasionally, leakage occurs, allowing coolant to enter unintended areas of the enclosure. If the coolant is electrically conductive, it can bridge terminals with relatively large potential differences. This bridging can initiate an electrolytic process in which the coolant is electrolyzed, and once sufficient energy is conducted for electrolysis, the coolant begins to boil. This boiling can create localized thermal conditions that can lead to the runaway thermal conditions described above.

[0004] Oily fluids are recognized as a potential alternative to heat transfer fluids in battery pack applications. Oily fluids offer excellent heat transfer and, due to their low conductivity, can be used in direct contact with electrical components. However, oily fluids have the disadvantage of increased flammability when the oil is aerosolized. Having dielectric oily heat transfer fluids with good fluid flow properties for cooling and reduced flammability would be beneficial. [Overview of the Initiative] [Means for solving the problem]

[0005] The present invention provides systems, methods, and fluids for cooling electrical components. In one embodiment, the present invention relates to a dielectric oily heat transfer fluid comprising a water-immiscible oil component and 0.001% to 1% by weight of a polymer additive component, wherein the polymer additive component comprises a polyolefin polymer having a number average molecular weight of at least about 20,000 as measured by gel permeation chromatography. In another embodiment, the present invention relates to a dielectric oily heat transfer fluid comprising a water-immiscible oil component and 500 ppm or less of a polymer additive component, wherein the polymer additive component comprises a polyolefin polymer having a number average molecular weight of at least about 20,000 as measured by gel permeation chromatography. In yet another embodiment, the present invention relates to a system and method in which a dielectric oily heat transfer fluid is in contact with electrical components. These embodiments are described in more detail below. [Modes for carrying out the invention]

[0006] Various preferred features and embodiments are described below by non-limiting examples.

[0007] The disclosed technology provides, among other things, a dielectric oily heat transfer fluid. The dielectric oily heat transfer fluid comprises a) a non-conductive, non-aqueous, and non-aqueous miscible fluid and b) a polymer additive component. As used herein, the term "a" in "a" polymer additive" or "a" fluid is used to mean "at least one," including one or more of the elements described, as well as two or more, three or more, and so on.

[0008] Non-conductive, non-aqueous, and non-aqueous miscible fluid One component of the disclosed technology is a non-conductive, non-aqueous, and non-aqueous miscible fluid. This fluid may be selected from any of the base oils in Groups I through V of the American Petroleum Institute's (API) Base Oil Interchangeability Guidelines (2011).

[0009] [Table 1]

[0010] Groups I, II, and III are mineral oil-based stocks. Other commonly recognized categories of base oils may be used even if not officially specified by the API. Group II+ refers to Group II materials with a viscosity index of 110–119 and lower volatility than other Group II oils, and Group III+ refers to Group III materials with a viscosity index of 130 or higher.

[0011] Many non-aqueous miscible oily fluids can function in the method and / or system of the present invention, but in one embodiment of the present invention, the non-aqueous miscible oily fluid may be selected from isoparaffins.

[0012] Isoparaffins (or isoparaffinic oils) are saturated hydrocarbon compounds containing at least one hydrocarbyl branch sufficient to provide fluidity at both cryogenic and cryogenic temperatures. The isoparaffins of the present invention may include natural and synthetic oils, oils derived from the hydrocracking, hydrolysis, and hydrofinishing of refined oils, re-refined oils, or mixtures thereof.

[0013] Synthetic oily fluids can be produced primarily by isomerizing straight-chain hydrocarbons to generate branched hydrocarbons. Straight-chain hydrocarbons can be of natural origin, synthetically prepared, or derived from the Fischer-Tropsch reaction or similar processes. Isoparaffins can be derived from hydrogen-isomerized waxes, typically hydrogen-isomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, oils can be prepared by the Fischer-Tropsch gas liquefaction synthesis procedure, as well as by other gas-liquefied oils.

[0014] Suitable isoparaffins can be obtained from natural, renewable sources. Natural (or bio-derived) oils refer to materials derived from renewable biological resources, organisms, or entities, and are distinct from materials derived from petroleum or equivalent raw materials. Natural sources of hydrocarbon oils include fatty acid triglycerides, hydrolyzed or partially hydrolyzed triglycerides, or transesterified triglyceride esters, such as fatty acid methyl esters (or FAME (fatty acid methyl ester)). Suitable triglycerides include, but are not limited to, palm oil, soybean oil, sunflower oil, rapeseed oil, olive oil, linseed oil, and related materials. Other triglyceride sources include, but are not limited to, algae, animal fats, and zooplankton. Linear and branched hydrocarbons can be obtained from or extracted from vegetable oils and hydrolyzed and / or hydrogen-isomerized in the same manner as synthetic oils to produce isoparaffins.

[0015] Another class of isoparaffin oils includes polyolefins. Polyolefins are well known in the art. In one embodiment, a polyolefin may be derived from an olefin having 2 to 24 carbon atoms. Derivable or derivable means that the polyolefin is polymerized from a starting polymerizable olefin monomer or a mixture thereof having the described number of carbon atoms. In an embodiment, a polyolefin may be derived from an olefin having 3 to 24 carbon atoms. In some embodiments, a polyolefin may be derived from an olefin having 4 to 24 carbon atoms. In a further embodiment, a polyolefin may be derived from an olefin having 5 to 20 carbon atoms. In yet another embodiment, a polyolefin may be derived from an olefin having 6 to 18 carbon atoms. In yet another embodiment, a polyolefin may be derived from an olefin having 8 to 14 carbon atoms. In an alternative embodiment, a polyolefin may be derived from an olefin having 8 to 12 carbon atoms.

[0016] In many cases, polymerizable olefin monomers include one or more of ethylene, propylene, isobutene, 1-butene, isoprene, 1,3-butadiene, or mixtures thereof. A useful example of polyolefin is polyisobutylene. Polymerizable olefins may also include certain dienes containing 1,3-dienes such as 1,3-butadiene and isoprene, as well as higher olefins that can be directly derived from such dienes, such as terpenes, for example, farnesene or partially hydrogenated terpenes.

[0017] Polyolefins also include poly-α-olefins that can be derived from (or are derived from) α-olefins. The α-olefins can be linear, branched, or mixtures thereof. Examples include monoolefins such as propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. Other examples of α-olefins include 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, and mixtures thereof. An example of a useful α-olefin is 1-dodecene. An example of a useful poly-α-olefin is poly-decene.

[0018] Polyolefins can also be copolymers of at least two different olefins, also known as olefin copolymers (OCP). These copolymers are preferably copolymers of α-olefins having 2 to about 28 carbon atoms, preferably copolymers of ethylene and at least one α-olefin having 3 to about 28 carbon atoms, typically copolymers of the formula CH2=CHR1, where R1 is a linear or branched alkyl radical containing 1 to 26 carbon atoms. Preferably, R1 in the above formula can be alkyl of 1 to 8 carbon atoms, more preferably alkyl of 1 to 2 carbon atoms. Preferably, the polymer of olefin is an ethylene-propylene copolymer.

[0019] When the olefin copolymer contains ethylene, the ethylene content is preferably in the range of 20 to 80 weight percent, more preferably 30 to 70 weight percent. When propylene and / or 1-butene are used as comonomers together with ethylene, the ethylene content of such copolymers is most preferably 45 to 65 percent, although higher or lower ethylene contents can exist.

[0020] In one embodiment, the oily fluid may be substantially free of ethylene and its polymers. The composition may be completely free of ethylene and its polymers. Substantially free means that the composition contains less than 50 ppm, or less than 30 ppm, or even less than 10 ppm, or less than 5 ppm, or even less than 1 ppm of a given material.

[0021] In one embodiment, the oily fluid may be substantially free of propylene and its polymers. In another embodiment, the oily fluid may be completely free of propylene and its polymers. The polyolefin polymer prepared from the aforementioned olefin monomers may have a number average molecular weight of 140 to 5000. The polyolefin polymer prepared from the aforementioned olefin monomers may also have a number average molecular weight of 200 to 4750. The polyolefin polymer prepared from the aforementioned olefin monomers may also have a number average molecular weight of 250 to 4500. The polyolefin polymer prepared from the aforementioned olefin monomers may also have a number average molecular weight of 500 to 4500. The polyolefin polymer prepared from the aforementioned olefin monomers may also have a number average molecular weight of 750 to 4000, as measured by gel permeation chromatography (GPC) using a polystyrene standard. GPC using a polystyrene standard is the standard method used for all Mn cited in this reference.

[0022] A mixture of mineral oil and synthetic oil, such as polyalphaolefin oil and / or polyester oil, may be used.

[0023] In another embodiment of the present invention, the oily fluid may be a saturated hydrocarbon compound containing 8 to 50 carbon atoms and having at least one hydrocarbyl branch containing at least one carbon atom. In one embodiment, the saturated hydrocarbon compound may have at least 10 or at least 12 carbon atoms. In one embodiment, the saturated hydrocarbon compound may contain 14 to 34 carbon atoms, provided that the longest continuous chain of carbon atoms is 24 or less in length.

[0024] In some embodiments, the oily fluid will have the longest continuous chain of carbon atoms with a carbon length of 24 or fewer.

[0025] In some embodiments, the saturated hydrocarbon compound may be a branched acyclic compound having a molecular weight of 140 g / mol to 550 g / mol, or 160 g / mol to 480 g / mol, as determined by size exclusion chromatography (SEC, also known as gel permeation chromatography or GPC), liquid chromatography, gas chromatography, mass spectrometry, NMR, or a combination thereof.

[0026] Mineral oils often contain cyclic structures, also known as aromatic or naphthenic cycloparaffins. In one embodiment, the isoparaffins contain saturated hydrocarbon compounds that do not contain or substantially contain cyclic structures. "Substantially contained" means that the mineral oil contains less than 1 mol%, or less than 0.75 mol%, or less than 0.5 mol%, or even less than 0.25 mol% of cyclic structures. In some embodiments, the mineral oil is completely free of cyclic structures.

[0027] Group IV hydrocarbon base oils (also known as polyalphaolefins, i.e., PAOs) are known in the art and are prepared by oligomerization or polymerization of linear alphaolefins (typically 1-decene, 1-octene, 1-dodecine, or combinations thereof). PAOs are characteristically water white oils with excellent low-temperature viscosity properties (as measured) and high viscosity indices. Typical PAOs suitable for use as thermal fluids include PAO-2, PAO-4, PAO-5, and PAO-6, i.e., about 2, 4, 5, and 6 m² / s, respectively, and mixtures thereof. Certain ester oils and ether oils have also been found to provide particularly improved heat transfer when used as dielectric oily heat transfer fluids in the disclosed methods.

[0028] Suitable esters for use as dielectric oily heat transfer fluids include esters of monocarboxylic acids and monohydric alcohols; diesters of diols and monocarboxylic acids, and diesters of dicarboxylic acids and monohydric alcohols; polyol esters of monocarboxylic acids, and polyesters of monohydric alcohols and polycarboxylic acids; and mixtures thereof. Esters can be broadly classified into two categories: synthetic and natural.

[0029] Suitable synthetic esters as dielectric oily heat transfer fluids include esters of monocarboxylic acids (such as neopentanoic acid and 2-ethylhexanoic acid) and dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acid and alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, linoleic acid, alkyl malonic acid, and alkenyl malonic acid) with any of the following monohydric alcohols (e.g., butyl alcohol, pentyl alcohol, neopentyl alcohol, hexyl alcohol, octyl alcohol, iso-octyl alcohol, nonyl alcohol, decyl alcohol, isodecyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, and propylene glycol). Specific examples of these esters include dibutyladipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctylsebacate, diisooctylazelate, diisodecylazelate, dioctylphthalate, didecylphthalate, diecoisylsebacate, 2-ethylhexyl diester of linoleic acid dimers, and composite esters formed by reacting 1 mole of sebaciic acid with 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid. Other synthetic esters include C5-C 12 Examples include those made from monocarboxylic acids, polyols, and polyol ethers, such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol. Esters may also be monoesters of monocarboxylic acids and monohydric alcohols.

[0030] Natural (or bio-derived) esters refer to materials derived from renewable biological resources, organisms, or entities, and are distinct from materials derived from petroleum or equivalent raw materials. Suitable natural esters as dielectric oily heat transfer fluids include fatty acid triglycerides, hydrolyzed or partially hydrolyzed triglycerides, or transesterified triglyceride esters such as fatty acid methyl esters (or FAME), or esters derived from the metathesis of unsaturated fatty acids. Suitable triglycerides include, but are not limited to, palm oil, soybean oil, sunflower oil, rapeseed oil, olive oil, linseed oil, and related materials. Other triglyceride sources include, but are not limited to, algae, animal fats, and zooplankton. Other examples of natural bio-derived esters include fatty acid oligomers, such as those marketed by Biosynthetic Technologies under the trademark Estolides®.

[0031] Other suitable oily fluids include alkylated aromatic oils (e.g., alkylated naphthalenes), low-viscosity naphthenic mineral oils, and (poly)ether oils. Alkylene oxide polymers and interpolymers and their derivatives, in which terminal hydroxyl groups are modified, for example, by esterification or etherification, constitute other classes of known synthetic lubricants that may be used. An example of a (poly)ether base oil is diethylene glycol dibutyl ether.

[0032] Polymer additives The compositions of the present invention contain high molecular weight polymer components. The high molecular weight polymer components may include one or more polymers having a number average molecular weight of at least about 20,000 Daltons. In one embodiment, polymers useful as or in polymer additive components can be prepared by polymerizing α-olefin monomers, or mixtures of α-olefin monomers, or mixtures containing ethylene and at least one C3-C28 α-olefin monomer, in the presence of a catalyst system containing at least one metallocene (e.g., a cyclopentadienyl-transition metal compound) and an almoxane compound.

[0033] Suitable polymer species of olefin polymers include ethylene propylene copolymer, ethylene-propylene-α-olefin terpolymer, ethylene-α-olefin copolymer, ethylene propylene copolymer further containing a non-conjugated diene, and isobutylene / conjugated diene copolymer, each of which can then be supplied together with graftable functional groups.

[0034] The ethylene-propylene or higher α-monoolefin copolymer may consist of 15-80 mol% ethylene and 20-85 mol% propylene or higher monoolefin, and in some embodiments, the molar ratio is 30-80 mol% ethylene and 20-70 mol% of at least one C3-C10 α-monoolefin, for example, 50-80 mol% ethylene and 20-50 mol% propylene. The terpolymer deformation of the aforementioned polymer may contain up to 15 mol% of unconjugated dienes or trienes.

[0035] In these embodiments, the polymer substrate, such as an ethylene copolymer or terpolymer, may be an oil-soluble, substantially linear, rubbery material. In certain embodiments, the polymer may also be in a form other than substantially linear, i.e., a branched polymer or a star-shaped polymer. The polymer may also be a random copolymer or block copolymer, comprising diblocks and higher-order blocks, tapered blocks, and various other structures. These types of polymer structures are known in the art, and their preparation is within the capabilities of those skilled in the art.

[0036] Other olefin monomers used to prepare polymers for the polymer additive components of the present invention may also include polymerizable olefins, as well as specific dienes such as 1,3-butadiene and isoprene, and higher olefins that can be directly derived from dienes such as terpenes, for example, farnesene or partially hydrogenated terpenes.

[0037] The terms polymer and copolymer are commonly used to encompass ethylene and / or higher alpha-monoolefin polymers, copolymers, terpolymers, or interpolymers. These materials may contain small amounts of other olefin monomers, provided that their fundamental properties are not substantially altered.

[0038] Another useful class of polymers consists, for example, of polymers prepared by cationic polymerization of isobutene or styrene. A common polymer from this class is polyisobutene, obtained by polymerization of a C4 purified stream having a butene content of 35-75% by mass and an isobutene content of 30-60% by mass in the presence of a Lewis acid catalyst such as aluminum trichloride or boron trifluoride, with aluminum trichloride being preferred. A suitable monomer source for producing poly-n-butene is petroleum feedstreams such as raffinate II. These feedstreams are disclosed in the art, such as in U.S. Patent No. 4,952,739. Polyisobutylene is a suitable polymer for the present invention because it is readily available from butene streams by cationic polymerization (e.g., using AlCl3 or BF3 catalysts).

[0039] Polyisobutylene is known to be prepared by cationic polymerization using boron halides, particularly boron trifluoride (European Patent Application Publication No. 206756, U.S. Patent No. 4,316,973, and British Patents Nos. 525542(A) and 828367(A)). Polymerization of isobutylene can be controlled to obtain polyisobutylene having a number-average molecular weight (Mn) much higher than 1,000,000.

[0040] In one embodiment, the olefin polymer is a copolymer of olefins having four or more carbon atoms. In one embodiment, the olefin polymer (polyolefin) contains 50 to 100% by weight of units derived from at least one olefin monomer having four or more carbon atoms. In a typical embodiment, the olefin may be an unsaturated aliphatic hydrocarbon such as butene, isobutylene (or isobutene), butadiene, isoprene, or a combination thereof.

[0041] The polyolefin polymers of the present invention may have number-average molecular weights (by gel permeation chromatography, according to polystyrene standards) of 20,000 to 10,000,000, 50,000 to 2,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000. In other embodiments, the olefin polymer is polyisobutylene having a number-average molecular weight of at least 50,000, at least 100,000, or at least 250,000 to 850,000, 600,000, or 500,000. Specific ranges include 250,000 to 750,000 or 250,000 to 500,000. The unit of number-average molecular weight as described herein is the Dalton.

[0042] The polymer additive component may be present in the dielectric oily fluid composition of the present invention at a weight basis of 0.001 to 1%, or 0.003 to 0.8%, or 0.005 to 0.5%, or 0.01 to 0.1%, or 0.02 to 0.05%, for example, 0.003 to 0.1%, or even further 0.003 to 0.01%. In another embodiment, the polymer additive component may be present in the dielectric oily heat transfer fluid at a concentration of 1000 ppm (parts per million) or less, or 800 ppm or less, or 500 ppm or less, or 300 ppm or less, or 100 ppm or less, or 10 ppm to 50 ppm, or even further 20 to 40 ppm. The concentration of the polymer in the dielectric oily fluid composition is measured on an oil-free basis.

[0043] The polymer additive components used in the present invention consist of or may contain polyolefin polymers as described herein. In one embodiment, the polymer components may substantially not contain other polymer components not described herein. For example, polyolefin and polyisobutylene polymers useful as polymer additive components of the present invention may contain 5 mol% or less (less than 3%, less than 2%, less than 1%) of vinyl-based non-olefin monomers copolymerized with the olefin. This may include vinyl monomers such as styrene, or other non-olefin monomers such as acrylates.

[0044] Dielectric oily fluid The precise formulation of dielectric oily fluids depends on the system in which the dispersion is used and the desired properties required for that system. For example, the thermal conductivity, viscosity, flash point, and dielectric properties of a dispersion will differ depending on whether the fluid is used to cool a battery pack in an automobile or to cool a computer server farm.

[0045] Dielectric oily fluids can be formulated by first selecting at least one nonconductive, non-aqueous, and non-aqueous miscible fluid having the desired dielectric properties, flash point, and viscosity for a selected application. For a fluid to be effective as a cooling thermal fluid, its shear viscosity must be fairly low. In this invention, the inventors have found that the addition of a small amount of high molecular weight polymer additive allows the fluid to maintain the low viscosity necessary for effective cooling, but provides an unexpected increase in extensional viscosity. The increase in extensional viscosity increases the droplet size of the fluid when the oily fluid is sprayed or aerosolized. As the droplet size increases in this way, the flammability of the sprayed fluid decreases.

[0046] To achieve the unexpected advantages of the present invention, at least one polymer additive can be selected to impart desired viscosity characteristics to the fluid. The polymer additive is selected and added to the fluid in an amount that increases the extensional viscosity of the fluid without causing a noticeable or significant increase in the shear viscosity of the fluid without the additive. In other words, the polymer additive is selected and added in an amount that does not change the shear viscosity of the non-aqueous miscible fluid without the polymer additive and the non-aqueous miscible fluid with the polymer additive by more than 5%.

[0047] In one embodiment, the desired concentration of a polymer additive can be determined by the intrinsic viscosity of the polymer. For some of the polymer additives described herein, the intrinsic viscosity is given by the Mark-Houwink formula.

number

[0048] Once at least one non-conductive, non-aqueous, and non-aqueous miscible fluid and polymer additive component are selected, the dielectric oily fluid of the present invention can then be prepared according to standard techniques known in the art for combining polymer additives with oil. For example, the dielectric oily fluid of the present invention can be prepared by simply mixing the polymer additive in a non-conductive, non-aqueous, and non-aqueous miscible fluid.

[0049] The dielectric constant (also called relative permittivity) is an important characteristic of heat transfer fluids for immersion cooling systems. To avoid the problem of current leakage, dielectric oily fluids may have a dielectric constant of 10.0 or less, as measured according to ASTM D924. The dielectric constant of dielectric oily fluids may also be 7.5 or less, as measured according to ASTM D924. The dielectric constant of dielectric oily fluids may also be 5 or less, as measured according to ASTM D924. The dielectric constant of dielectric oily fluids may also be 4.0 or less, as measured according to ASTM D924.

[0050] Dielectric oily fluids may also have a kinematic viscosity measured at 100°C of at least 0.7 cSt, or at least 0.9 cSt, or at least 1.1 cSt, or 0.7–7.0 cSt, or 0.9–6.5 cSt, or even 1.1–6.0 cS, as measured according to ASTM D445_100. For a given chemical group and pump power, fluids with higher viscosity have lower hydrodynamic efficiency due to higher resistance to flow.

[0051] Dielectric oily fluids may have dynamic viscosity. It is understood that kinematic viscosity and dynamic viscosity are related. The dielectric oily fluid of the present invention has a viscosity of 1 MPa. * s~10MPa * s, or even 1.7MPa~5MPa * It may have a dynamic viscosity of s. The dynamic viscosity is 100 to 500 s at 25°C. 1 This can be measured using an ARES G2 rheometer (TA Instruments) that employs a double-walled concentric cylindrical shape at the given shear rate.

[0052] Often, heat transfer fluids need to flow freely at very low temperatures. In one embodiment, the dielectric oily fluid may have a pour point of at least -50°C, or at least -40°C, or at least -30°C, as measured according to ASTM D5985. In one embodiment, the dielectric oily fluid may have an absolute viscosity of 900 cP or less at -30°C, or 500 cP or less at -30°C, or 100 cP or less at -30°C, as measured according to ASTM D2983.

[0053] Dielectric oily fluids may have a flash point of at least 50°C, or at least 60°C, or at least 75°C, or at least 100°C, as measured according to ASTM D56.

[0054] Cooling method The disclosed technology provides a dielectric oily fluid as described herein and a method for cooling electrical components by bringing the electrical components into contact with the fluid and operating the electrical components. In one example, contact with the electrical components may be via a bath containing the dielectric oily fluid.

[0055] Electrical components include any electronic equipment that utilizes electricity and generates thermal energy that must be dissipated to prevent overheating. Examples include avionics, computer electronics such as microprocessors, uninterruptible power supplies (UPS), and power electronics (IGBTs, SCRs, thyristors, capacitors, diodes, transistors, rectifiers, etc.). Further examples include inverters, DC-DC converters, chargers, phase-change inverters, electric motors, electric motor controllers, and DC-AC inverters.

[0056] While several examples of electrical components have been provided, heat transfer fluids can be used in any assembly or for any electrical component to provide an improved heat transfer fluid with low-temperature performance without significantly increasing the electrical conductivity and potential flammability of the mixture.

[0057] This method is particularly useful for heat transfer from battery systems in electric vehicles such as electric cars and trucks, or even in electrified mass transit vehicles such as trains or trams. The main electrical component in electrified transport is often the battery module, which may comprise one or more battery cells stacked relative to each other to form the module. Heat can be generated by each battery cell during charging and discharging operations, or transferred to the battery cells during key-off conditions of the electrified vehicle as a result of relatively extreme (i.e., hot) ambient conditions. Therefore, the battery module includes a heat transfer system for thermally managing the battery module across the entire range of ambient and / or operating conditions. In practice, the operation of the battery module can occur during its operation, or during the use and discharge of power from the battery module, such as during charging. Regarding charging, the use of a heat transfer fluid can enable the battery module to be charged to at least 75% of its total battery capacity, which can be recovered in less than 15 minutes.

[0058] Similarly, electrical components in electrified transport may include fuel cells, solar cells, solar panels, and photovoltaic batteries that require cooling by heat transfer fluids. Such electrified transport may also include conventional internal combustion engines, such as those found in hybrid vehicles.

[0059] Electrified transport may also include electric motors as electrical components. Electric motors may be used anywhere along the vehicle's drivetrain to operate, for example, the transmission, axles, and differentials. Such electric motors may be cooled by a heat transfer system using a heat transfer fluid.

[0060] This method may include providing a heat transfer system containing electrical components that require cooling. The heat transfer system will include, among other things, a bath in which the electrical components may be positioned in a manner that allows the electrical components to be in direct fluid communication with a dielectric oily fluid. The bath is in fluid communication with a heat transfer fluid reservoir and a heat exchanger containing the dielectric oily fluid.

[0061] Electrical components may operate in conjunction with the operation of a heat transfer system. The heat transfer system may operate, for example, by circulating a dielectric oily fluid through it.

[0062] For example, a heat transfer system may include means for pumping a cooled dielectric oily fluid from a heat transfer fluid reservoir into a bath and pumping a heated dielectric oily fluid back from the bath through a heat exchanger into the heat transfer fluid reservoir. In this way, the heat transfer system can be operated so that while the electrical components are operating, the cooled dielectric oily fluid is supplied to the electrical components to absorb the heat generated by the electrical components, and the dielectric oily fluid heated by the electrical components is removed and sent to a heat exchanger for cooling and recirculation, returning to the heat transfer fluid reservoir.

[0063] The thermal management systems disclosed herein are capable of removing heat at a rate that enables rapid charging of batteries. The target for fast charging includes 120–600 kW. Considering a 95% efficiency in charging, the heat transfer fluid needs to remove up to 30 kW in 10–60 minutes.

[0064] Various embodiments of the compositions disclosed herein may optionally include one or more additional performance additives. These additional performance additives may include one or more flame retardants, smoke suppressants, antioxidants, combustion inhibitors, metal deactivators, fluid additives, corrosion inhibitors, foaming inhibitors, deemulsifiers, pour point depressants, seal swelling agents, and any combination or mixture thereof. Typically, a fully formulated heat transfer fluid may contain one or more of these performance additives, and often may contain a package of multiple performance additives. In one embodiment, one or more additional additives may be present in the dielectric oily fluid at concentrations of 0.01% to 3% by weight, or 0.05% to 1.5% by weight, or 0.1% to 1.0% by weight.

[0065] As used herein, the term "hydrocarbyl" is used in its ordinary sense, as is well known to those skilled in the art. Specifically, it refers to a group having carbon atoms directly bonded to the rest of the molecule and having primarily hydrocarbon properties. Examples of hydrocarbyl groups include: Hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, as well as aromatic, aliphatic, and alicyclic substituted aromatic substituents, and cyclic substituents in which the ring is completed via another part of the molecule (e.g., two substituents together form a ring); Substitutive hydrocarbon substituents, i.e., substituents in the context of the present invention that contain non-hydrocarbon groups that do not primarily alter the hydrocarbon properties of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); Heterosubstituted substituents, in the context of the present invention, are substituents that primarily possess hydrocarbon properties, but otherwise contain non-carbon atoms in a ring or chain composed of carbon atoms, and include substituents as pyridyl, furyl, thienyl, and imidazolyl. Examples of heteroatoms include sulfur, oxygen, and nitrogen. Generally, there are two or fewer, or one or fewer, non-hydrocarbon substituents for every 10 carbon atoms in the hydrocarbyl group, and alternatively, there may be no non-hydrocarbon substituents in the hydrocarbyl group.

[0066] Since some of the materials described above may interact in the final formulation, it is known that the components of the final formulation may differ from those initially added. For example, metal ions (e.g., detergents) may migrate to other acidic or anionic sites of other molecules. The products formed thereby, including those formed when the compositions of the present invention are used in their intended applications, may not be readily apparent. Nevertheless, all such modifications and reaction products are included within the scope of the present invention. The present invention encompasses compositions prepared by mixing the materials described above.

[0067] The present invention is useful for cooling electrical components during operation and can be better understood by referring to the following examples.

Example

[0068] Example- First, a series of heat transfer fluids are prepared by selecting a series of non-conductive, non-aqueous, and non-water-miscible fluids. The fluids range from simple isoparaffinic hydrocarbons to organic esters and ether compounds. The non-conductive, non-aqueous, and non-water-miscible fluids are listed in Table 1.

[0069]

Table 2

[0070] As shown in Table 2, a series of polymer additives are selected.

[0071]

Table 3

[0072] The effects of the addition of polymer additives to the heat fluids of the present invention are summarized in Tables 3 and 4 below. The fluids were treated with the polymers of the present invention and evaluated for changes in dynamic viscosity, extensional viscosity, and time to fluid capillary breakage.

[0073] [Table 4] 1 100-500s 1 Measurements were taken using an ARES G2 rheometer (TA Instruments) with a double-walled concentric cylindrical shape at a shear rate (at 25°C). 2 Extensional viscosity was measured using a capillary rupture-up extensional rheometer (CABER1, Thermo-Haake) equipped with an ultrafast video camera (Fastcam F4, Photron, Inc.). The fluid was placed between two flat 4 mm diameter plates separated by an initial gap h0 = 1.5 mm. As the gap slowly increased at a rate of approximately 3 mm / s, the fluid bridge became unstable and ruptured. Capillary rupture occurred with some delay due to the fluid's resistance to rupture. This resistance is due to shear and extensional viscosity. To ensure reproducibility, each experimental test was repeated at least five times. The filament diameter was measured using digital imaging. A specially designed objective lens with a ×10 lens provided a resolution of 1.9 microns / pixel. For calibration, a set of standard wires from Thermo-Haake (0.02, 0.03, 0.06, 0.12, 0.25, 0.50, and 1 mm) was used. 3 Capillary rupture time was determined from the time dependence of the filament mid-diameter (i.e., when the diameter is close to zero) from at least three measurements. For a series of images typically recorded at a frame rate of 10,000–30,000 frames / second, the filament mid-diameter was measured using specially designed image analysis software (Edgehog, developed at Prof. CH. Clasen lab, KU Leuven, Belgium). 4 Thermal conductivity measured at 25°C according to ASTM D7896.

[0074] [Table 5] 1Kinematic viscosity at 40°C (ASTM D445) 2 Extensional viscosity was measured using a capillary rupture-up extensional rheometer (CABER1, Thermo-Haake) equipped with an ultrafast video camera (Fastcam F4, Photron, Inc.). The fluid was placed between two flat 4 mm diameter plates separated by an initial gap h0 = 1.5 mm. As the gap slowly increased at a rate of approximately 3 mm / s, the fluid bridge became unstable and ruptured. Capillary rupture occurred with some delay due to the fluid's resistance to rupture. This resistance is due to shear and extensional viscosity. To ensure reproducibility, each experimental test was repeated at least five times. The filament diameter was measured using digital imaging. A specially designed objective lens with a ×10 lens provided a resolution of 1.9 microns / pixel. For calibration, a set of standard wires from Thermo-Haake (0.02, 0.03, 0.06, 0.12, 0.25, 0.50, and 1 mm) were used. 3 Capillary rupture time was determined from the time dependence of the filament mid-diameter (i.e., when the diameter is close to zero) from at least three measurements. For a series of images typically recorded at a frame rate of 10,000–30,000 frames / second, the filament mid-diameter was measured using specially designed image analysis software (Edgehog, developed at Prof. CH. Clasen lab, KU Leuven, Belgium). 4 Thermal conductivity measured at 30°C according to ASTM D7896. 5 Includes a 0.6% by weight dispersant additive package.

[0075] As the results show, non-aqueous thermal fluids treated with low levels of high-viscosity polymers exhibit an increase in both maximum extensional viscosity and fluid capillary rupture time.

[0076] The fluid mixtures of the present invention may also be evaluated to determine their flash point and their ability to absorb and disperse heat. For example, additional tests of the fluids of the present invention may include flash point (ASTM D92), heat capacity at 40°C by differential scanning calorimetry (DSC), thermal conductivity at 50°C (ASTM D7896), and dielectric strength (ASTM D1816).

[0077] The sample also includes a specific wall area ("A wall A test may be conducted to determine the forced convection heat transfer coefficient "h" of a sample fluid passing through a pipe having a wall temperature ("T"). A higher heat transfer coefficient may be used to determine whether one fluid performs better than another. This test may involve pumping the sample fluid through the pipe at a constant pump output. The fluid temperature at the pipe inlet is controlled by a heat exchanger to a set inlet temperature, such as 35°C. The pipe wall may be heated with a DC power supply providing constant power ("P"). wall The temperature (T) can be measured using a thermocouple. The thermocouple is placed in the fluid flow and the fluid temperature (T) can be measured. fluid To measure the '', the device is placed in the same location near the wall temperature measurement point. After a steady state is reached, data is collected and averaged over 60 seconds. The forced convection heat transfer coefficient is calculated using equation X.

[0078]

number

[0079] Formula Y Referenced above

[0080]

number

[0081] As used herein, the transitional term “comprising,” which is synonymous with “including,” “containing,” or “characterized by,” is comprehensive or open-ended and does not exclude additional unlisted elements or method steps. However, in each instance of “comprising” herein, the term is also intended to encompass, as alternative embodiments, the phrases “consisting essentially of” and “consisting of,” where “consisting of” excludes any unspecified elements or steps, and “consisting essentially of” allows for the inclusion of additional unlisted elements or steps that do not substantially affect the essential or basic and novel features of the composition or method under consideration.

[0082] For illustrative purposes, certain representative embodiments and details have been provided, but it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention. In this regard, the scope of the invention should be limited only by the following claims. For example, the present invention provides the following items: (Item 1) A method for cooling electrical components, The electrical component is brought into contact with a dielectric oily heat transfer fluid, wherein the dielectric oily heat transfer fluid comprises (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component, and (b) a polymer additive component in an amount of 0.001 to 1% by weight as measured on an oil-free standard, and the polymer additive component comprises or consists of one or more polyolefin polymers having a number average molecular weight of at least about 20,000 (by gel permeation chromatography, according to a polystyrene standard), and the electrical component is brought into contact with the dielectric oily heat transfer fluid, wherein the dielectric oily heat transfer fluid comprises (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component, and (b) a polymer additive component in an amount of 0.001 to 1% by weight as measured on an oil-free standard, and the polymer additive component comprises at least one polyolefin polymer having a number average molecular weight of about 20,000 (by gel permeation chromatography, according to a polystyrene standard), and the electrical component is brought into contact with the dielectric oily heat transfer fluid, wherein the dielectric oily heat transfer fluid comprises (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component, and (b) a polymer additive component in an amount of 0.001 to 1% by weight as measured on an oil-free standard, and wherein the polymer additive component comprises at least one polyolefin polymer having a number average molecular weight of about 20,000 (by gel permeation chromatography, according to a polystyrene standard), A method comprising operating the aforementioned electrical component. (Item 2) The method according to item 1, wherein the electrical component comprises a battery. (Item 3) The aforementioned battery is used to power an electric vehicle, as described in item 2. (Item 4) The method according to item 1, wherein the electrical component comprises at least one of aircraft electronics, computer electronics, inverters, DC-DC converters, chargers, inverters, electric motors, and electric motor controllers. (Item 5) The dielectric oily heat transfer fluid has a dielectric constant of 3.0 or less as measured according to ASTM D924, as described in any one of items 1 to 4. (Item 6) The water-immiscible oil component is a hydrocarbon, as described in any one of items 1 to 5. (Item 7) The method according to item 6, wherein the hydrocarbon comprises an isoparaffin oil containing at least one saturated hydrocarbon compound having 8 to 50 carbon atoms. (Item 8) The method according to item 7, wherein the at least one saturated hydrocarbon compound contains at least 10 carbon atoms and at least one hydrocarbyl branch and has a single continuous carbon chain of 24 or fewer carbon atoms. (Item 9) The method according to item 7, wherein the at least one saturated hydrocarbon compound comprises a branched acyclic compound having a molecular weight of 140 g / mol to 550 g / mol. (Item 10) The method according to any one of items 1 to 9, wherein the non-aqueous miscible hydrocarbon oil component comprises alkylene oxide polymers and interpolymers, and derivatives thereof, wherein the terminal hydroxyl groups are modified by esterification or etherification. (Item 11) The method according to any one of items 1 to 10, wherein the one or more polyolefin polymers have a number average molecular weight of 20,000 to 10,000,000, 50,000 to 2,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000 (by gel permeation chromatography, according to polystyrene standards). (Item 12) The method according to any one of items 1 to 11, wherein the one or more polyolefin polymers include or consist of a polyisobutylene polymer having a number average molecular weight of at least about 50,000 (by gel permeation chromatography, according to polystyrene standards) as measured by gel permeation chromatography. (Item 13) The method according to item 12, wherein the polyisobutylene polymer has a number average molecular weight (by gel permeation chromatography, according to polystyrene standards) of at least 50,000 or at least 100,000 or at least 250,000 to 2,000,000 or 1,500,000 or 850,000 or 600,000 or 500,000. (Item 14) The polyisobutylene polymer has a number-average molecular weight of 250,000 to 750,000 or 250,000 to 500,000 (by gel permeation chromatography, according to polystyrene standards), as described in item 13. (Item 15) The dielectric oily heat transfer fluid comprises the polymer additive component in an amount of 800 ppm or less, or 500 ppm or less, or 300 ppm or less, or 100 ppm or less, according to any one of items 1 to 14. (Item 16) The dielectric oily heat transfer fluid comprises 10 ppm to 50 ppm or 20 to 40 ppm of the polymer additive component, according to any one of items 1 to 15. (Item 17) A cooling system for an electric vehicle comprising a battery pack in contact with a dielectric oily heat transfer fluid, wherein the dielectric oily heat transfer fluid comprises (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component and (b) a polymer additive component in an amount of 0.001 to 1% by weight, or 0.003 to 0.8% by weight, or 0.005 to 0.5% by weight, or 0.01 to 0.1% by weight, or 0.02% to 0.05% by weight, wherein the polymer additive component comprises or consists of one or more polyolefin polymers having a number average molecular weight of at least about 20,000 (by gel permeation chromatography, according to polystyrene standards). (Item 18) The cooling system according to item 17, wherein the cooling system is an immersion cooling system, and the battery pack is in fluid communication with a heat transfer fluid reservoir containing the dielectric oily heat transfer fluid. (Item 19) The dielectric oily heat transfer fluid has a dielectric constant of 3.0 or less as measured according to ASTM D924, as described in the cooling system of item 17 or 18. (Item 20) The water-immiscible oil component includes hydrocarbons, as described in any one of items 17 to 19 of the Cooling System. (Item 21) The cooling system according to item 20, wherein the hydrocarbon comprises an isoparaffin oil containing at least one saturated hydrocarbon compound having 8 to 50 carbon atoms. (Item 22) The cooling system according to item 21, wherein the at least one saturated hydrocarbon compound contains at least 10 carbon atoms and at least one hydrocarbyl branch and has a single continuous carbon chain of 24 or fewer carbon atoms. (Item 23) The cooling system according to item 22, wherein the at least one saturated hydrocarbon compound comprises a branched acyclic compound having a molecular weight of 140 g / mol to 550 g / mol. (Item 24) The cooling system according to any one of items 17 to 23, wherein the non-aqueous miscible hydrocarbon oil component comprises alkylene oxide polymers and interpolymers, and derivatives thereof, wherein the terminal hydroxyl groups are modified by esterification or etherification. (Item 25) The cooling system according to any one of items 17 to 24, wherein the one or more polyolefin polymers have a number average molecular weight of 20,000 to 10,000,000, 50,000 to 2,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000 (by gel permeation chromatography, according to polystyrene standards). (Item 26) The cooling system according to any one of items 17 to 25, wherein the one or more polyolefin polymers include or consist of a polyisobutylene polymer having a number average molecular weight of at least about 50,000 as measured by gel permeation chromatography (by gel permeation chromatography, according to polystyrene standards). (Item 27) The cooling system according to item 26, wherein the polyisobutylene polymer has a number average molecular weight (by gel permeation chromatography, according to polystyrene standards) of at least 50,000 or at least 100,000 or at least 250,000 to 2,000,000 or 1,500,000, 850,000 or 600,000 or 500,000. (Item 28) The cooling system according to item 35, wherein the polyisobutylene polymer has a number average molecular weight of 250,000 to 750,000 or 250,000 to 500,000 (by gel permeation chromatography, according to polystyrene standards). (Item 29) The cooling system according to any one of items 17 to 28, wherein the dielectric oily heat transfer fluid contains the polymer additive component in an amount of 800 ppm or less, or 500 ppm or less, or 300 ppm or less, or 100 ppm or less. (Item 30) The cooling system according to any one of items 17 to 29, wherein the dielectric oily heat transfer fluid contains 10 ppm to 50 ppm of the polymer additive component. (Item 31) A dielectric oily heat transfer fluid comprising (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component, and (b) 0.001 to 1% by weight of a polymer additive component, wherein the polymer additive component comprises or consists of one or more polyolefin polymers having a number average molecular weight of at least about 20,000 (by gel permeation chromatography, according to polystyrene standards). (Item 32) The dielectric oil heat transfer fluid is the dielectric oil heat transfer fluid according to item 31, having a dielectric constant of 3.0 or less as measured in accordance with ASTM D924. (Item 33) The water-immiscible oil component is a dielectric oily heat transfer fluid according to item 31 or 32, comprising hydrocarbons. (Item 34) The dielectric oily heat transfer fluid according to item 33, wherein the hydrocarbon comprises an isoparaffin oil containing at least one saturated hydrocarbon compound having 8 to 50 carbon atoms. (Item 35) The dielectric oily heat transfer fluid according to item 34, wherein the at least one saturated hydrocarbon compound contains at least 10 carbon atoms and at least one hydrocarbyl branch and has a single continuous carbon chain of 24 or fewer carbon atoms. (Item 36) The dielectric oily heat transfer fluid according to item 35, wherein the at least one saturated hydrocarbon compound comprises a branched acyclic compound having a molecular weight of 140 g / mol to 550 g / mol. (Item 37) The dielectric oily heat transfer fluid according to any one of items 31 to 36, wherein the non-aqueous miscible hydrocarbon oil component comprises alkylene oxide polymers and interpolymers, and derivatives thereof, wherein the terminal hydroxyl groups are modified by esterification or etherification. (Item 38) The dielectric oily heat transfer fluid according to any one of items 31 to 37, wherein the one or more polyolefin polymers have a number average molecular weight of 20,000 to 10,000,000, 50,000 to 2,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000 (by gel permeation chromatography, according to polystyrene standards). (Item 39) The dielectric oily heat transfer fluid according to any one of items 31 to 38, wherein the one or more polyolefin polymers include or consist of a polyisobutylene polymer having a number average molecular weight of at least about 50,000 (by gel permeation chromatography, according to polystyrene standards) as measured by gel permeation chromatography. (Item 40) The dielectric oily heat transfer fluid according to item 39, wherein the polyisobutylene polymer has a number average molecular weight (by gel permeation chromatography, according to polystyrene standards) of at least 50,000, or at least 100,000, or at least 250,000 to 2,000,000, or 1,500,000, or 850,000, or 600,000, or 500,000. (Item 41) The polyisobutylene polymer has a number average molecular weight of 250,000 to 750,000 or 250,000 to 500,000 (by gel permeation chromatography, according to polystyrene standards), and is a dielectric oily heat transfer fluid as described in item 40. (Item 42) The dielectric oily heat transfer fluid is a dielectric oily heat transfer fluid according to any one of items 31 to 41, comprising the polymer additive component in an amount of 800 ppm or less, or 500 ppm or less, or 300 ppm or less, or 100 ppm or less. (Item 43) The dielectric oily heat transfer fluid is the dielectric oily heat transfer fluid according to any one of items 31 to 42, comprising 10 ppm to 50 ppm or 20 to 40 ppm of the polymer additive component. (Item 44) Use of dielectric oil heat transfer fluids as described in items 31-43 for cooling electrical components.

Claims

1. A method for cooling electrical components, The method involves bringing the electrical components into contact with a dielectric oily heat transfer fluid, wherein the dielectric oily heat transfer fluid comprises (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component, and (b) a polymer additive component in an amount of 0.001 to 0.01% by weight as measured on an oil-free standard, and the polymer additive component comprises or consists of one or more polyolefin polymers having a number average molecular weight of at least 50,000 (by gel permeation chromatography, according to a polystyrene standard), and the electrical components are brought into contact with the dielectric oily heat transfer fluid. A method comprising operating the aforementioned electrical component.

2. The method according to claim 1, wherein the electrical component comprises a battery.

3. The method according to claim 2, wherein the battery is used to operate an electric vehicle.

4. The method according to claim 1, wherein the electrical component comprises at least one of aircraft electronic equipment, computer electronic equipment, inverter, DC-DC converter, charger, inverter, electric motor, and electric motor controller.

5. The method according to any one of claims 1 to 4, wherein the dielectric oily heat transfer fluid has a dielectric constant of 3.0 or less as measured according to ASTM D924.

6. The method according to any one of claims 1 to 5, wherein the non-conductive, non-aqueous, and non-aqueous miscible oil component comprises a hydrocarbon.

7. The method according to claim 6, wherein the hydrocarbon comprises an isoparaffin oil containing at least one saturated hydrocarbon compound having 8 to 50 carbon atoms.

8. The method according to claim 7, wherein the at least one saturated hydrocarbon compound contains at least 10 carbon atoms and at least one hydrocarbyl branch and has a single continuous carbon chain of 24 or fewer carbon atoms.

9. The method according to claim 7, wherein the at least one saturated hydrocarbon compound comprises a branched acyclic compound having a molecular weight of 140 g / mol to 550 g / mol.

10. The method according to any one of claims 1 to 9, wherein the non-conductive, non-aqueous, and non-aqueous miscible oil component comprises alkylene oxide polymers and interpolymers, and derivatives thereof, wherein the terminal hydroxyl groups are modified by esterification or etherification.

11. The method according to any one of claims 1 to 10, wherein the one or more polyolefin polymers have a number average molecular weight of 50,000 to 10,000,000, 50,000 to 2,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000 (by gel permeation chromatography, according to a polystyrene standard).

12. The method according to any one of claims 1 to 11, wherein the one or more polyolefin polymers include or consist of a polyisobutylene polymer.

13. The method according to claim 12, wherein the polyisobutylene polymer has a number average molecular weight (by gel permeation chromatography, according to polystyrene standards) of at least 100,000 or at least 250,000 to 2,000,000 or 1,500,000 or 850,000 or 600,000 or 500,000.

14. The method according to claim 13, wherein the polyisobutylene polymer has a number average molecular weight of 250,000 to 750,000 or 250,000 to 500,000 (by gel permeation chromatography, according to a polystyrene standard).

15. The method according to any one of claims 1 to 14, wherein the dielectric oily heat transfer fluid contains 10 ppm to 50 ppm or 20 to 40 ppm of the polymer additive component.

16. A cooling system for an electric vehicle comprising a battery pack in contact with a dielectric oily heat transfer fluid, wherein the dielectric oily heat transfer fluid comprises (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component and (b) 0.001 to 0.01% by weight, or 0.003 to 0.01% by weight, or 0.005 to 0.01% by weight of a polymer additive component, wherein the polymer additive component comprises or consists of one or more polyolefin polymers having a number average molecular weight of at least 50,000 (by gel permeation chromatography, according to polystyrene standards).

17. The cooling system according to claim 16, wherein the cooling system is an immersion cooling system, and the battery pack is in fluid communication with a heat transfer fluid reservoir containing the dielectric oily heat transfer fluid.

18. The cooling system according to claim 16 or 17, wherein the dielectric oily heat transfer fluid has a dielectric constant of 3.0 or less as measured according to ASTM D924.

19. The cooling system according to any one of claims 16 to 18, wherein the non-conductive, non-aqueous, and non-aqueous miscible oil component comprises a hydrocarbon.

20. The cooling system according to claim 19, wherein the hydrocarbon comprises an isoparaffin oil containing at least one saturated hydrocarbon compound having 8 to 50 carbon atoms.

21. The cooling system according to claim 20, wherein the at least one saturated hydrocarbon compound contains at least 10 carbon atoms and at least one hydrocarbyl branch and has a single continuous carbon chain of 24 or fewer carbon atoms.

22. The cooling system according to claim 21, wherein the at least one saturated hydrocarbon compound comprises a branched acyclic compound having a molecular weight of 140 g / mol to 550 g / mol.

23. The cooling system according to any one of claims 16 to 22, wherein the non-conductive, non-aqueous, and non-aqueous miscible oil component comprises alkylene oxide polymers and interpolymers, and derivatives thereof, wherein the terminal hydroxyl groups are modified by esterification or etherification.

24. The cooling system according to any one of claims 16 to 23, wherein the one or more polyolefin polymers have a number average molecular weight of 50,000 to 10,000,000, 50,000 to 2,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000 (by gel permeation chromatography, according to polystyrene standards).

25. The cooling system according to any one of claims 16 to 24, wherein the one or more polyolefin polymers include or consist of a polyisobutylene polymer.

26. The cooling system according to claim 25, wherein the polyisobutylene polymer has a number average molecular weight (by gel permeation chromatography, polystyrene standard) of at least 100,000 or at least 250,000 to 2,000,000 or 1,500,000, 850,000 or 600,000 or 500,000.

27. The cooling system according to claim 25, wherein the polyisobutylene polymer has a number average molecular weight of 250,000 to 750,000 or 250,000 to 500,000 (by gel permeation chromatography, according to a polystyrene standard).

28. The cooling system according to any one of claims 16 to 27, wherein the dielectric oily heat transfer fluid contains 10 ppm to 50 ppm of the polymer additive component.

29. A dielectric oily heat transfer fluid comprising (a) a non-conductive, non-aqueous, and non-aqueous miscible oil component, and (b) 0.001 to 0.01% by weight of a polymer additive component, wherein the polymer additive component comprises or consists of one or more polyolefin polymers having a number average molecular weight of at least 50,000 (by gel permeation chromatography, according to the polystyrene standard).

30. The dielectric oil heat transfer fluid according to claim 29, wherein the dielectric oil heat transfer fluid has a dielectric constant of 3.0 or less as measured according to ASTM D924.

31. The dielectric oily heat transfer fluid according to claim 29 or 30, wherein the non-conductive, non-aqueous, and non-aqueous miscible oil component comprises a hydrocarbon.

32. The dielectric oily heat transfer fluid according to claim 31, wherein the hydrocarbon comprises an isoparaffin oil containing at least one saturated hydrocarbon compound having 8 to 50 carbon atoms.

33. The dielectric oily heat transfer fluid according to claim 32, wherein the at least one saturated hydrocarbon compound contains at least 10 carbon atoms and at least one hydrocarbyl branch and has a single continuous carbon chain of 24 or fewer carbon atoms.

34. The dielectric oily heat transfer fluid according to claim 33, wherein the at least one saturated hydrocarbon compound comprises a branched acyclic compound having a molecular weight of 140 g / mol to 550 g / mol.

35. The dielectric oily heat transfer fluid according to any one of claims 29 to 34, wherein the non-conductive, non-aqueous, and non-aqueous miscible oil component comprises alkylene oxide polymers and interpolymers, and derivatives thereof, wherein the terminal hydroxyl groups are modified by esterification or etherification.

36. The dielectric oily heat transfer fluid according to any one of claims 29 to 35, wherein the one or more polyolefin polymers have a number average molecular weight of 50,000 to 10,000,000, 50,000 to 2,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000 (by gel permeation chromatography, according to polystyrene standards).

37. The dielectric oily heat transfer fluid according to any one of claims 29 to 36, wherein the one or more polyolefin polymers include or consist of a polyisobutylene polymer.

38. The dielectric oily heat transfer fluid according to claim 37, wherein the polyisobutylene polymer has a number average molecular weight (by gel permeation chromatography, polystyrene standard) of at least 100,000 or at least 250,000 to 2,000,000 or 1,500,000 or 850,000 or 600,000 or 500,000.

39. The dielectric oily heat transfer fluid according to claim 38, wherein the polyisobutylene polymer has a number average molecular weight of 250,000 to 750,000 or 250,000 to 500,000 (by gel permeation chromatography, according to a polystyrene standard).

40. The dielectric oily heat transfer fluid according to any one of claims 29 to 39, wherein the dielectric oily heat transfer fluid contains 10 ppm to 50 ppm or 20 to 40 ppm of the polymer additive component.

41. Use of dielectric oily heat transfer fluids according to claims 29 to 40 for cooling electrical components.

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