ORGANIC HEAT TRANSFER SYSTEMS, METHODS, AND FLUIDS

Abstract

The disclosed technology relates to heat transfer fluids and heat transfer systems and methods using heat transfer fluids. In particular, the technology relates to heat transfer fluids having low electrical conductivity, low flammability and low freezing points that provide excellent peak temperature reduction in heat transfer systems, such as those for cooling the power systems of electric vehicles or computer servers.

Description

[Technical field]

[0001] The disclosed technology relates to heat transfer fluids and heat transfer systems and methods using heat transfer fluids. In particular, the technology relates to heat transfer fluids having balanced electrical conductivity, low flammability and low freezing points that provide excellent peak temperature reduction in heat transfer systems, such as those for cooling electric vehicles or computer server power systems. [Background technology]

[0002] The operation of the power source generates heat. A heat transfer system in communication with the power source regulates the generated heat and ensures that the power source operates at an optimal temperature. The heat transfer system typically includes a heat transfer fluid that facilitates the absorption and dissipation of heat from the power source. Traditional aqueous heat transfer fluids, typically consisting of water and glycol, tend to freeze. Traditional heat transfer fluids can also exhibit extremely high electrical conductivity, often in the range of 3000 microsiemens per centimeter (μS / cm) or higher. This high electrical conductivity can adversely affect the heat transfer system by promoting corrosion of metal components, and in the case of power sources where the heat transfer system is exposed to electrical current, such as in fuel cells, computer electronics, and the like, the high electrical conductivity can lead to electrical short circuits and electric shock.

[0003] Some OEMs and tier suppliers have expressed concerns about the electrical properties of both electric vehicle (EV) transmission fluids (E-TF) and EV coolants. Specifically, the concern is that these fluids may be conductive enough to short out the electric motor itself. This means that the conductivity of the oil needs to be as low as possible to ensure transmission reliability. This concern is echoed in a recent paper on lubricants for hybrid electric vehicles, Tang, T., Devlin, M., Mathur, N., Henly, T. et al., "Lubricants for (Hybrid) Electric Transmissions", SAE Int. J. Fuel Lubr. 6(2):289-294, 2013, doi:10.4271 / 2013-01-0298, where the authors recommend an arbitrary upper limit for the conductivity of the new oil.

[0004] However, the strategy of striving for the lowest possible conductivity does not take into account the possibility that static electricity may build up and discharge if the oil has insufficient conductivity. Such static electricity build up and discharge may result in equipment damage and may accelerate the rate of oil degradation. Generally, there are two concerns regarding the electrical conductivity of ATFs and other lubricants. The conductivity must be low enough for the lubricant to be a good electrical insulator and high enough to dissipate static charges. In practice, determining the range of acceptable conductivity for a specific application and hardware configuration is a challenging task. This range will vary slightly for different applications, different equipment types, different system designs, and different fluid flow scenarios. What is needed is a heat transfer system and method that uses an inexpensive heat transfer fluid that has balanced electrical conductivity. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Tang, T., Devlin, M., Mathur, N., Henly, T. et al., "Lubricants for (Hybrid) Electric Transmissions", SAE Int. J. Fuels Lubr. 6(2):289-294, 2013, doi:10.4271 / 2013-01-0298 Summary of the Invention

[0006] Thus, the disclosed technology solves the problem of safety concerns when cooling electrical components by operating the electrical components immersed in a heat transfer fluid. Surprisingly, it has been discovered that not only does the conductivity of the fluid need to be controlled to minimize electrostatic discharge, but the conductivity of the fluid needs to be controlled so as not to affect battery charge durability, interfere with the function of the device, or cause arcing, short circuits, or electrolysis of the fluid.

[0007] To meet electrical conductivity requirements, an additive package has been devised for addition to the heat transfer fluid, which includes a hydrocarbon oil, a metal-containing detergent, and a dispersant. The heat transfer fluid may further include an ashless antioxidant.

[0008] The method and / or system is particularly useful in transferring heat from battery systems, such as in electric vehicles and uninterruptible power supplies, or from computing electronics, such as in servers and digital asset mining devices.

[0009] The present technique includes a method of lubricating an electrified driveline. The method includes applying a heat transfer fluid to the driveline and operating the driveline.

[0010] The present technology also includes a method of cooling an electrical component, such as a computer server, that includes immersing the electrical component in a bath of a heat transfer fluid and operating the electrical component.

[0011] Also provided herein is a submersion coolant system that may be used, for example, in an electric vehicle or a server farm. The system may include a battery pack or computer server located in a vessel that is in fluid communication with a heat transfer fluid reservoir filled with the heat transfer fluid discussed herein.

[0012] The method and / or system may also find application in other electrical components, such as, for example, aircraft electronics, other computer electronics, inverters, DC-DC converters, AC-DC converters, chargers, phase change inverters, electric motors, electric motor controllers, and DC-AC inverters. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Various preferred features and embodiments are described below by way of non-limiting example.

[0014] The disclosed technology provides a method of cooling an electrical component by immersing the electrical component in a bath containing a hydrocarbon (optionally isoparaffinic) oil and an oxygenate and operating the electrical component.

[0015] Electrical components include any electronic device that utilizes electrical power and generates thermal energy that must be dissipated to prevent the electronic device from overheating. Examples include aircraft electronics, computer servers, microprocessors, uninterruptable power supplies (UPS), power electronics (such as IGBTs, SCRs, thyristors, capacitors, diodes, transistors, rectifiers), energy storage devices, and other computer electronics. Further examples include inverters, DC-DC converters, AC-DC converters, chargers, phase change inverters, electric motors, electric motor controllers, and DC-AC inverters.

[0016] Although several examples of electrical components have been provided, the heat transfer fluid 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.

[0017] The method and / or system is particularly useful for transferring heat from a battery system, such as a battery system in an electric vehicle, such as an electric car, truck, or even an electrified mass transit vehicle, such as a train or streetcar. A major part of the electrical components in an electrified transportation vehicle is often a battery module, which may include one or more battery cells stacked against each other to form a battery module. Heat may be generated by each battery cell during charging and discharging operations, or may be transferred to the battery cells during a key-off state of the electrified vehicle as a result of relatively extreme (i.e., hot) ambient conditions. Thus, the battery module includes a heat transfer system for thermally managing the battery module over a full range of ambient and / or operating conditions. In fact, operation of the battery module may occur during the use and drainage of power from the battery module, such as during operation of the battery module or during charging of the battery module. A charging system, including an AC power source, a regulator, a charging cable, and a fuse, may also generate heat, and the method and / or system may be used thereto. With regard to charging, the use of a heat transfer fluid can enable charging of the battery modules to at least 75% of the total battery capacity being recovered in less than 15 minutes.

[0018] Similarly, the electrical components in an electrified vehicle may include fuel cells, solar cells, solar panels, photovoltaic cells, etc. that require cooling by a heat transfer fluid. Such electrified vehicles may also include conventional internal combustion engines, such as in a hybrid vehicle.

[0019] Electrified vehicles may also include electric motors as electrical components. Electric motors may be used anywhere along the vehicle driveline to operate the transmission, axles, and differentials, for example. Such electric motors may be cooled by a heat transfer system that uses a heat transfer fluid.

[0020] The method may be used, for example, to lubricate a drivetrain that includes an electrified transmission and / or an electric motor.

[0021] The method may be used, for example, to lubricate a drivetrain that includes an electrified transmission and / or an electric motor.

[0022] The method and / or system is also particularly useful for the transfer of heat from computer electronic devices such as computer servers and from other computer electronic devices.

[0023] The method and / or system may include providing a heat transfer system to house an electrical component requiring cooling. The heat transfer system includes, among other things, a vessel in which the electrical component may be positioned in a manner that allows the electrical component to be in direct fluid contact with a heat transfer fluid. The vessel is in fluid communication with a heat transfer fluid reservoir and a heat exchanger.

[0024] The electrical components may operate in conjunction with the operation of a heat transfer system, which may be operated by circulating a heat transfer fluid through the heat transfer system, for example, via pumping or via natural circulation.

[0025] For example, the heat transfer system may include means for pumping cooled heat transfer fluid from the heat transfer fluid reservoir to the bath, pumping heated heat transfer fluid out of the bath through a heat exchanger, and returning to the heat transfer fluid reservoir. In some embodiments, the heat transfer system may use natural circulation to drive the flow of the fluid. Natural circulation includes a flow that changes density as a result of heat input and drives the flow of the fluid by gravity. Thus, while the electrical components are operating, the heat transfer system may also be operated to provide cooled heat transfer fluid to the electrical components to absorb heat generated by the electrical components and to remove heat transfer fluid heated by the electrical components to the heat exchanger for cooling and recirculation to the heat transfer fluid reservoir.

[0026] The dielectric constant (also called the relative permittivity) is an important characteristic of a heat transfer fluid for an immersion cooling system. To avoid problems with current leakage, the heat transfer fluid in which the electrical components are immersed may have a dielectric constant of 5.0 or less, as measured according to ASTM D924. The dielectric constant of the heat transfer fluid at room temperature (i.e., 20-25°C) may also be less than 4.5, 4.0, 3.0, 2.5, or less than 2.3, or less than 2.0.

[0027] The heat transfer fluid 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 between 0.7 and 7.0 cSt, or between 0.9 and 6.5 cSt, or between 1.1 and 6.0 cSt, as measured according to ASTM D445_100. For a given chemical family being pumped at a given power output, a higher viscosity fluid is typically less effective at removing heat given the higher resistance to flow. The same phenomenon also occurs for natural convection systems.

[0028] The immersed heat transfer fluid should be free flowing at very low temperatures. In one embodiment, the heat transfer fluid has a pour point of at least -10°C, or at least -25°C, or at least -30°C, or at least -40°C, or at least -50°C, as measured according to ASTM D5985. In one embodiment, the heat transfer fluid has 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.

[0029] The heat transfer fluid contains a hydrocarbon (sometimes an isoparaffin) oil and an oxygenate.

[0030] The hydrocarbon (e.g., isoparaffinic) oil has a flash point, as measured according to ASTM D92 and / or ASTM D93, of at least 50°C, or at least 60°C, or at least 75°C, or at least 100°C, or at least 150°C, or at least 200°C, or at least 250°C.

[0031] Hydrocarbon oils [including isoparaffins (or isoparaffin oils)] are saturated hydrocarbon compounds containing at least one hydrocarbyl branch or at least one saturated five- or six-membered hydrocarbyl ring sufficient to provide fluidity at both cryogenic and high temperatures. Hydrocarbon oils (isoparaffins) of the present invention can include natural and synthetic oils, oils derived from hydrocracking, hydrogenation, and hydrofinishing of refined oils, rerefined oils, or mixtures thereof. Hydrocarbon oils include isoparaffin oils (or isoparaffins), i.e., branched non-cyclic hydrocarbons, or cycloparaffin oils (or cycloparaffins, also called naphthenic oils).

[0032] Synthetic isoparaffin oils may be produced by isomerization of primarily linear hydrocarbons to produce branched hydrocarbons. The linear hydrocarbons may be naturally occurring, synthetically prepared, or derived from a Fischer-Tropsch reaction or similar process. Isoparaffins may be derived from hydroisomerized wax, typically hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, the oils may be prepared by Fischer-Tropsch gas-to-liquid synthesis procedures, as well as other gas-to-liquid oils.

[0033] Suitable isoparaffins may 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 feedstocks. 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 FAMEs). Suitable triglycerides include, but are not limited to, palm oil, soybean oil, sunflower oil, rapeseed oil, olive oil, linseed oil, and related materials. Other sources of triglycerides include, but are not limited to, algae, tallow, and zooplankton. Linear and branched hydrocarbons may be obtained or extracted from vegetable oils and hydrofined and / or hydroisomerized in a manner similar to synthetic oils to produce isoparaffins.

[0034] Another class of isoparaffin oils includes polyalphaolefins (PAOs). Polyolefins are well known in the art. In one embodiment, the polyolefins may be derived from olefins having 2 to 28 carbon atoms. By derived or derived, it is meant that the polyolefin is polymerized from starting polymerizable olefin monomers or mixtures thereof having the recited number of carbon atoms. In an embodiment, the polyolefins may be derived from olefins having 3 to 24 carbon atoms. In some embodiments, the polyolefins may be derived from olefins having 4 to 24 carbon atoms. In further embodiments, the polyolefins may be derived from olefins having 5 to 20 carbon atoms. In yet further embodiments, the polyolefins may be derived from olefins having 6 to 18 carbon atoms. In yet further embodiments, the polyolefins may be derived from olefins having 8 to 14 carbon atoms. In an alternative embodiment, the polyolefins may be derived from olefins having 8 to 12 carbon atoms.

[0035] Often the polymerizable olefin monomer comprises one or more of propylene, isobutene, 1-butene, isoprene, 1,3-butadiene, or mixtures thereof. An example of a useful polyolefin is polyisobutylene.

[0036] Polyolefins also include poly-α-olefins derivable (or derived) from α-olefins. The α-olefins can be linear or 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, and the like. 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.

[0037] Polyolefins may also be copolymers of at least two different olefins, also known as olefin copolymers (OCPs). These copolymers are preferably copolymers of α-olefins having from 2 to about 28 carbon atoms, preferably copolymers of ethylene and at least one α-olefin having from 3 to about 28 carbon atoms, typically copolymers of formula CH2=CHR1, where R1 is a linear or branched alkyl radical containing from 1 to 26 carbon atoms. Preferably, R1 in the above formula may be an alkyl of 1 to 8 carbon atoms, more preferably an alkyl of 1 to 2 carbon atoms. Preferably, the polymer of olefin is an ethylene-propylene copolymer.

[0038] When the olefin copolymer comprises ethylene, the ethylene content preferably ranges from 20 to 80 weight percent, more preferably from 30 to 70 weight percent. When propylene and / or 1-butene are used as comonomers with ethylene, the ethylene content of such copolymers is most preferably from 45 to 65 percent, although higher or lower ethylene contents can be present.

[0039] The hydrocarbon (e.g., isoparaffin) oil may be substantially free of ethylene and its polymers. The composition may be completely free of ethylene and its polymers. By substantially free, it is meant that the composition contains less than 50 ppm, or less than 30 ppm, or even less than 10 ppm or 5 ppm, or even less than 1 ppm of a given material.

[0040] The hydrocarbon (e.g., isoparaffin) oil may be substantially free of propylene and its polymers. The hydrocarbon (e.g., isoparaffin) oil may be completely free of propylene and its polymers. The polyolefin polymers prepared from the aforementioned olefin monomers may have a number average molecular weight of 140 to 5000. The polyolefin polymers prepared from the aforementioned olefin monomers may also have a number average molecular weight of 200 to 4750. The polyolefin polymers prepared from the aforementioned olefin monomers may also have a number average molecular weight of 250 to 4500. The polyolefin polymers prepared from the aforementioned olefin monomers may also have a number average molecular weight of 500 to 4500. The polyolefin polymers prepared from the aforementioned olefin monomers may also have a number average molecular weight of 750 to 4000 as measured by gel permeation chromatography with polystyrene standards.

[0041] Isoparaffinic oils can be saturated hydrocarbon compounds containing from 8 carbon atoms up to 50 carbon atoms and having at least one hydrocarbyl branch containing at least one carbon atom. In one embodiment, the saturated hydrocarbon compounds can have at least 10 or at least 12 carbon atoms. In one embodiment, the saturated hydrocarbon compounds can contain from 14 to 34 carbon atoms, provided that the longest continuous chain of carbon atoms is 24 carbons or less in length.

[0042] In an embodiment, the isoparaffinic oil has a longest continuous chain of carbon atoms that is 24 carbons or less in length.

[0043] In embodiments, the saturated hydrocarbon compound can 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 measured by size exclusion chromatography (SEC) (SEC is also called gel permeation chromatography, GPC), liquid chromatography, gas chromatography, mass spectrometry, NMR, or a combination thereof.

[0044] Mineral oils often contain cyclic structures, i.e. cycloparaffins, also called aromatics or naphthenes. In one embodiment, isoparaffins comprise saturated hydrocarbon compounds that are free or substantially free of cyclic structures. By substantially free, it is meant that there is 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 the mineral oil. In some embodiments, the mineral oil is completely free of cyclic structures.

[0045] In an embodiment, the hydrocarbon oil may be a cycloparaffin oil (cycloparaffin). The cycloparaffin may be derived from a mineral oil. The cycloparaffin contains at least one saturated hydrocarbyl five- or six-membered ring. The cycloparaffin oil may contain at least 29 weight percent polycycloparaffins, i.e., two or more edge-sharing rings.

[0046] The hydrocarbon (e.g., isoparaffin) oil is the base compound of the heat transfer fluid. As such, the hydrocarbon (e.g., isoparaffin) oil constitutes the remainder of the composition after all oxygenates and other additives have been added. The hydrocarbon oil may be present in an amount of at least 60%, at least 70%, at least 80%, at least 90%, or at least 95% by weight of the composition. That is, the hydrocarbon oil may be present in an amount of 60-99%, or even 70-98.5%, or 80-98%, or 90-97 or 97.5% by weight. In some embodiments, the hydrocarbon oil may be present in an amount of 80-99%, or even 81-98.5%, or 82-98%, or 83-97%, or 84-97.5% by weight. Oxygenate

[0047] The composition may also include an oxygenate material that can act synergistically with the hydrocarbon (e.g., isoparaffinic) oil to provide improved heat transfer, reduced kinematic viscosity, reduced low temperature viscosity, or increased flash point.

[0048] As used herein, oxygenates refer to organic (i.e., carbon-containing, also known as hydrocarbons) compounds that contain oxygen as one of their components. As used herein, oxygenates include hydrocarbons having at least one aprotic or protic oxygen for every two carbon atoms, or every three carbon atoms, or every four carbon atoms, or every five carbon atoms, or every six carbon atoms. Oxygenates also include hydrocarbons having at least one aprotic or protic oxygen for every seven carbon atoms, or every eight carbon atoms, or every twelve carbon atoms. Oxygenates also include hydrocarbons having at least one aprotic or protic oxygen for every sixteen carbon atoms, or every twenty carbon atoms.

[0049] The oxygenates may include, for example, alcohols, ester oils, and ether oils. The oxygenates may be present in the heat transfer fluid at about 1 to about 45% by weight, or in some cases, at about 1.5 to about 40% by weight, or in some cases, at about 2 to about 35% by weight. The oxygenates may also be present in the heat transfer fluid at about 2.5 to about 30% by weight, or in some cases, at about 3 to about 25% by weight. In some embodiments, the oxygenates may be present in the heat transfer fluid at about 1 to about 20% by weight, or in some cases, at about 1.5 to about 19% by weight, or in some cases, at about 2 to about 18% by weight. The oxygenates may also be present in the heat transfer fluid at about 2.5 to about 17% by weight, or in some cases, at about 3 to about 16% by weight.

[0050] Alcohols suitable for use in the heat transfer fluid include monohydric alcohols, such as ethanol, methanol, propylene alcohol derivatives such as n-butanol and tert-butanol, and isopropyl alcohol. Higher branched alcohols include isomers of pentanol, hexanol, heptanol, octanol, decanol, dodecanol, tetradecanol, hexadecanol, and combinations thereof. Examples of branched alcohols include 2-ethylhexanol, isooctanol, isodecanol, and isododecanol. As used herein, alcohol also includes polyols, such as propylene glycol, ethylene glycol, 1,4-butanediol, pentaerythritol, trimethylolpropane, and the like.

[0051] Suitable ethers for use as oxygenates in heat transfer fluids include those produced from petrochemical and renewable feedstocks. Examples include methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), ethyl tertiary butyl ether (ETBE), and tertiary amyl ethyl ether (TAEE). Other examples of ethers include tert-hexyl methyl ether (THEME), dioctyl ether, and diisopropyl ether. Polyethers are also contemplated herein under the term "ether" and include, for example, diethylene glycol dibutyl ether. Low molecular weight oligomers of polyalkylene glycols (i.e., polyalkylene oxides), including polyethylene glycol (PEG), polypropylene glycol (PPG), and mixed polymers thereof, may also be suitable. Polyethers include alkylene oxide polymers and oligomers containing 1 to 20 repeat units, or 2 to 10 repeat units, or 2 to 5 repeat units of ethylene oxide, propylene oxide, n-butylene oxide, or mixtures thereof. Suitable polyether compounds include 5,8,11,14-tetraoxaicosane, 1-(2-(2-butoxypropoxy)propoxy)propan-2-yl acetate, 2-(2-(2-(hexyloxy)ethoxy)ethoxy)ethyl oleate, 1-((1-((1-butoxypropan-2-yl)oxy)propan-2-yl)oxy)butane, 7,10,13,16,19-pentaoxaheptacosane, 2-(2-(2-(hexyloxy)ethoxy)ethoxy)ethyl 3,5,5-trimethylhexanoate, and combinations thereof.

[0052] The oxygenates can also be polyalkylene glycol esters by reacting a polyalkylene glycol with a fatty acid, such as, for example, caprylic acid, myristic acid, palmitic acid, stearic acid, and the like.

[0053] In some cases, the oxygenate may be an alcohol or an ether and may be present in the heat transfer fluid at about 1 to about 45 weight percent, or in some cases, at about 1.5 to about 40 weight percent, or at about 2 to about 35 weight percent. Alcoholic or etheric oxygenates may also be present in the heat transfer fluid at about 2.5 to about 30 weight percent, or at about 3 to about 25 weight percent.

[0054] Ester oils suitable for use as oxygenates in heat transfer fluids include esters of monocarboxylic acids and monohydric alcohols, di-esters of diols and monocarboxylic acids and di-esters 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.

[0055] Synthetic esters suitable for use as oxygenates in the heat transfer fluid may include esters of monocarboxylic acids (such as acetic acid, propionic acid, neopentanoic acid, 2-ethylhexanoic acid, and the like) and dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, linoleic acid, alkyl malonic acids, and alkenyl malonic acids) with any of a variety of 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 dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, diecocyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid. Other synthetic esters include those containing C5 to C6 12 Included are those made from monocarboxylic acids and polyols and polyol ethers, such as those made from neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol. The esters can also be monoesters of monocarboxylic acids and monohydric alcohols.

[0056] Suitable esters also include esters of hydroxy-substituted carboxylic acids, such as tartaric acid, malic acid, glycolic acid, and hydroxy fatty acids (eg, 12-hydroxystearic acid), in combination with monohydric alcohols, as described above.

[0057] Natural (or bio-based) esters refer to materials derived from renewable biological resources, organisms, or entities, and are distinct from materials derived from petroleum or equivalent sources. Natural esters suitable in heat transfer fluids include fatty acid triglycerides, hydrolyzed or partially hydrolyzed triglycerides, or transesterified triglyceride esters, such as fatty acid methyl esters (or FAMEs). 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, tallow, and zooplankton.

[0058] In some cases, the oxygenate may be an ester, which may be present in the heat transfer fluid at about 1 to about 20 weight percent, or in some cases, at about 1.5 to about 19 weight percent, or at about 2 to about 18 weight percent. The ester oxygenate may also be present in the heat transfer fluid at about 2.5 to about 17 weight percent, or at 3 to about 16 weight percent. Heat Transfer Additives

[0059] Heat transfer fluids may also include heat transfer additives. One class of heat transfer additives includes, for example, metallic and non-metallic particles. The particles of the present invention are generally dispersed solids, often dispersed in the presence of one or more stabilizers or surfactants. The particles of the present invention are often submicron sized, also referred to as nanoparticles.

[0060] For metal nanoparticles, the metal of the metal nanoparticles can include alkaline earth metals, such as magnesium, calcium, strontium, and barium.

[0061] The metal of the metal nanoparticles can include transition metals, such as scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, and cadmium.

[0062] The metal of the metal nanoparticles can include metals of the lanthanide series or actinide series, such as lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, thorium, protactinium, and uranium.

[0063] The metals of the metal nanoparticles can include post-transition metals, such as aluminum, gallium, indium, thallium, tin, lead, bismuth, and polonium.

[0064] The metal of the metal nanoparticles can include metalloids, such as boron, silicon, germanium, and antimony.

[0065] In certain embodiments, the metal may include aluminum. In embodiments, the metal may include iron. The metal may also include ruthenium. The metal may include cobalt. The metal may include rhodium. The metal may include nickel. The metal may include palladium. The metal may include platinum. The metal may include silver. The metal may include gold. The metal may include cerium. The metal may include samarium. The metal may include tungsten.

[0066] The metal nanoparticles may be present in their pure form or as oxides, carbides, nitrides, or any mixtures or combinations of these materials.

[0067] For example, the metal nanoparticles can be iron oxide (e.g., Fe2O3, Fe3O4), cobalt oxide (e.g., CoO), zinc oxide (e.g., ZnO), cerium oxide (e.g., CeO2), and titanium oxide (e.g., TiO2). Boron oxide (e.g., B2O3) is another metal nanoparticle that can be used. Aluminum oxide (e.g., Al2O3) is another metal nanoparticle that can be used. Magnesium oxide (e.g., MgO) is another metal nanoparticle that can be used. Tungsten oxide (e.g., W2O3, WO2, WO3, W2O5) is another metal nanoparticle that can be used.

[0068] Examples of metal carbide metal nanoparticles may include iron carbide (e.g., Fe3CH4), cobalt carbide (e.g., CoC, Co2C, Co3C), zinc carbide (e.g., ZnC), cerium carbide (e.g., CeC2), and titanium carbide (e.g., TiC). Boron carbide (e.g., B4C) is another metal nanoparticle that may be used. Aluminum carbide (e.g., Al4C3) is another metal nanoparticle that may be used. Tungsten carbide (e.g., WC) is another metal nanoparticle that may be used.

[0069] Examples of metal nitride nanoparticles include iron nitrides (e.g., Fe2N, Fe3N4, Fe4N, Fe7N3, Fe 16 Examples of metal nanoparticles that may be used include copper nitride (CuN), ...

[0070] The nanoparticles may also include non-metallic nanoparticles. Such non-metallic nanoparticles may be in the form of oxides, carbon, carbides, nitrides, or any mixture or combination of these materials. For example, the non-metallic nanoparticles may be graphene oxide or diamond.

[0071] The nanoparticles may have a D50 particle size of less than 1000 nm. In some embodiments, the nanoparticles may have a D50 particle size of less than 700 nm. The nanoparticles may have a D50 particle size of less than 500 nm. The nanoparticles may have a D50 particle size of less than 250 nm. The nanoparticles may have a D50 particle size of less than 100 nm. The nanoparticles may have a D50 particle size of less than 75 nm. The nanoparticles may have a D50 particle size of less than 50 nm. The nanoparticles may have a D50 particle size of 0.01 nm to 1000 nm. The nanoparticles may also have a D50 particle size of 0.1 nm to 100 nm. The nanoparticles may have a D50 particle size of 1 nm to 75 nm. The nanoparticles may have a D50 particle size of 10 nm to 50 nm. The D50 particle size can be measured by dynamic light scattering according to ASTM E2490-09(2015).

[0072] The nanoparticles may have an average aspect ratio of 1 to 5000. As used herein, "average aspect ratio" refers to the average ratio of the length of the particles in the nanoparticle mixture to the width of the particles in the mixture. The term "average" is intended to mean that any and all aspect ratios can be present, but the average aspect ratio across the entire collection is within the disclosed range. The measurement method for determining the average aspect ratio length and width is not important as long as the same measurement method is used for both measurements. The nanoparticles may also have an average aspect ratio of 1 to 2500. The nanoparticles may also have an average aspect ratio of 1 to 1000. The nanoparticles may also have an average aspect ratio of 1 to 500. The nanoparticles may also have an average aspect ratio of 1 to 250. The nanoparticles may also have an average aspect ratio of 1 to 100. The nanoparticles may also have an average aspect ratio of 1 to 50. The nanoparticles may also have an average aspect ratio of 1 to 25. The nanoparticles may also have an average aspect ratio of 1 to 100. The nanoparticles may also have an average aspect ratio of 1 to 50. The nanoparticles may also have an average aspect ratio of 1 to 25. The nanoparticles may also have an average aspect ratio of 1 to 10. The nanoparticles may also have an average aspect ratio of 10 to 5000. The nanoparticles may also have an average aspect ratio of 25 to 5000. The nanoparticles may also have an average aspect ratio of 50 to 5000. The nanoparticles may also have an average aspect ratio of 100 to 5000. The nanoparticles may also have an average aspect ratio of 250 to 5000. The nanoparticles may also have an average aspect ratio of 500 to 5000. The nanoparticles may also have an average aspect ratio of 1000 to 5000. The nanoparticles may also have an average aspect ratio of 2500 to 5000.

[0073] The heat transfer fluid may include at least one nanoparticle at a concentration of 0.5-30% by weight, based on the weight of the heat transfer fluid. In some embodiments, the heat transfer fluid may include at least one nanoparticle at a concentration of 0.75-25% by weight. In some embodiments, the heat transfer fluid may include at least one nanoparticle at a concentration of 1-20% by weight. In embodiments, the heat transfer fluid may include at least one nanoparticle at a concentration of 1.25-15% by weight. In some embodiments, the heat transfer fluid may include at least one nanoparticle at a concentration of 1.5-10% by weight.

[0074] However, care should be taken when administering nanoparticles so as not to exceed the constraints of the dielectric constant of the heat transfer fluid. Generally, this is not an issue unless more electrically conductive nanoparticles, such as nanoparticles in the form of pure metals, are used at high levels, typically 10% by weight or more. If there is concern, the heat transfer fluid can be formulated and the dielectric constant of the dispersion tested.

[0075] The nanoparticles are often administered with a surfactant suitable for binding the nanoparticles and keeping them dispersed in the heat transfer fluid, as would be readily apparent to one of skill in the art, which may include any surfactant or dispersant now known or hereafter developed.

[0076] In one embodiment, the heat transfer fluid may include a hydrocarbon oil, one or more polyether oxygenates, and one or more metallic or non-metallic particles.

[0077] Performance Additives

[0078] The heat transfer fluid also includes a performance additive package that balances the volume conductivity of the fluid. The performance additive package may include metal-containing detergents and dispersants.

[0079] The heat transfer fluid may further include a metal-containing detergent.

[0080] The metal-containing detergent may be an overbased detergent, a non-overbased detergent, or a mixture thereof. Typically, the detergent is overbased.

[0081] The metal-containing detergent may be a non-overbased detergent (sometimes called a neutral detergent). The TBN of the non-overbased metal-containing detergent may be 20 to less than 200, or 30 to 100, or 35 to 50 mgKOH / g. The TBN of the non-overbased metal-containing detergent may also be 20 to 175, or 30 to 100 mgKOH / g. When the non-overbased metal-containing detergent is prepared from a strong acid such as a hydrocarbyl-substituted sulfonic acid, the TBN may be lower (e.g., 0 to 50 mgKOH / g, or 10 to 20 mgKOH / g).

[0082] As used herein, the quoted values ​​of TBN and related TBN ranges are "as is", i.e., containing conventional amounts of diluent oil, which typically range from 30% to 60% (often 40% to 55%) by weight of the detergent components.

[0083] The metal-containing detergent may be, for example, an overbased detergent having a TBN of more than 200 mg KOH / g (typically from 250 to 600, or from 300 to 500 mg KOH / g).

[0084] Overbased metal-containing detergents may be formed by the reaction of a basic metal compound with an acidic detergent substrate, which may include an alkyl aromatic sulfonic acid (such as an alkyl naphthalene sulfonic acid, an alkyl toluene sulfonic acid, or an alkyl benzene sulfonic acid), an alkyl salicylic acid, or mixtures thereof.

[0085] The basic metal compound is used to provide basicity to the detergent. The basic metal compound is a compound of a metal hydroxide or oxide. The metal of the metal-containing detergent can be, for example, an alkali metal or an alkaline earth metal, such as zinc, sodium, calcium, barium, or magnesium. Typically, the metal of the metal-containing detergent can be sodium, calcium, or magnesium.

[0086] In one embodiment, the metal-containing detergent may be a sulfonate, or mixtures thereof. The sulfonates may be prepared from mono- or dihydrocarbyl-substituted benzene (or naphthalene, indenyl, indanyl, or bicyclopentadienyl) sulfonic acids, where the hydrocarbyl groups may contain 6 to 40, or 8 to 35, or 9 to 30 carbon atoms.

[0087] The hydrocarbyl groups may be derived from polypropylene, or linear or branched alkyl groups containing at least 10 carbon atoms. Examples of suitable alkyl groups include branched and / or linear decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, octadecenyl, nonodecyl, eicosyl, un-eicosyl, do-eicosyl, tri-eicosyl, tetra-eicosyl, penta-eicosyl, hexa-eicosyl, or mixtures thereof.

[0088] In one embodiment, the hydrocarbyl-substituted sulfonic acid is polypropene benzene sulfonic acid and / or C 16 ~C 24 The composition may comprise an alkyl benzene sulfonic acid, an alkyl benzene sulfonic acid, or a mixture thereof.

[0089] In one embodiment the metal sulfonate detergent may be a predominantly linear alkylbenzene sulfonate detergent having a metal ratio of at least 8. In some embodiments the linear alkyl group may be attached to the benzene ring at any position along the linear chain of the alkyl group, but often is attached at the 2-, 3- or 4-position of the linear chain, and sometimes predominantly at the 2-position.

[0090] When neutral or slightly basic, the metal sulfonate detergents may have a TBN of less than 100, or less than 75, typically from 20 to 50 mg KOH / g, or from 0 to 20 mg KOH / g.

[0091] If overbased, the metal sulfonate detergent may have a TBN of greater than 200, or from 300 to 550, or from 350 to 450 mg KOH / g.

[0092] Phenate detergents are typically derived from p-hydrocarbylphenols or generally alkylphenols. This type of alkylphenol can be overbased by coupling with sulfur, overbased by coupling with aldehydes, or carboxylated to form salicylate detergents. Suitable alkylsalicylates include those alkylated with oligomers of propylene, oligomers of butene, especially tetramers and pentamers of n-butene, and with alpha-olefins, isomerized alpha-olefins, and polyolefins such as polyisobutylene.

[0093] Metal-containing detergents may be overbased. Overbased detergents are known in the art. Overbased materials, also called overbased salts or super overbased salts, are generally single-phase homogeneous Newtonian systems characterized by a metal content in excess of the amount that should be present for neutralization according to the stoichiometry of the metal and the particular acidic organic compound reacting with the metal. Overbased materials are prepared by reacting an acidic material (typically an inorganic acid or a lower carboxylic acid, preferably carbon dioxide) with a mixture containing an acidic organic compound, a reaction medium containing at least one inert organic solvent for the acidic organic material (mineral oil, naphtha, toluene, xylene, etc.), a stoichiometric excess of a metal base, and a promoter such as calcium chloride, acetic acid, phenol, or alcohol. The acidic organic material usually has a sufficient number of carbon atoms to provide solubility in oil. The amount of excess metal is generally expressed in terms of metal ratio. The term "metal ratio" is the ratio of the total equivalents of metal to the equivalents of acidic organic compound. Neutral metal salts have a metal ratio of 1. A salt having 4.5 times the metal present in a normal salt has a metal excess of 3.5 equivalents, or a ratio of 4.5. The term "metal ratio" is also explained in the standard text "Chemistry and Technology of Lubricants", Second Edition, Edited by RM Mortier and ST Orszulik, Copyright 1997.

[0094] The overbased metal-containing detergent may be, for example, a sulfur-free phenate, a sulfur-containing phenate, a sulfonate, a salixarate, a salicylate, and mixtures thereof, or their borated equivalents. The overbased detergent may be borated with a borating agent such as boric acid.

[0095] Overbased metal-containing detergents may also include "hybrid" detergents formed with mixed surfactant systems containing phenate and / or sulfonate components, such as phenate / salicylate, sulfonate / phenate, sulfonate / salicylate, sulfonate / phenate / salicylate, etc. For example, if a hybrid sulfonate / phenate detergent could be used, this hybrid detergent would be considered equivalent in amount to separate phenate and sulfonate detergents that incorporate similar amounts of phenate soap and sulfonate soap, respectively.

[0096] Typically, the overbased metal-containing detergent may be a zinc, sodium, calcium, or magnesium salt of a phenate, a sulfur-containing phenate, a sulfonate, a salixarate, or a salicylate. The overbased salixarates, phenates, and salicylates typically have a total base number of 180 to 450 TBN. The overbased sulfonates typically have a total base number of 250 to 600, or 300 to 500. Overbased detergents are known in the art. In one embodiment, the sulfonate detergent may be a predominantly linear alkylbenzene sulfonate detergent having a metal ratio of at least 8. The predominantly linear alkylbenzene sulfonate detergent may be particularly useful in helping to improve fuel economy.

[0097] Typically, the overbased metal-containing detergent may be a calcium or magnesium overbased detergent, such as a calcium sulfonate or magnesium sulfonate detergent.

[0098] The detergent may be present in the heat transfer fluid at from 10 ppm to 5000 ppm, from 25 ppm to 4000 ppm, from 50 ppm to 3000 ppm, from 100 ppm to 2000 ppm, from 50 ppm to 500 ppm.

[0099] The dispersant (also called a surfactant) may be a succinimide dispersant, a Mannich dispersant, a succinamide dispersant, a succinate ester, an amide, or an ester-amide, or a mixture thereof. In one embodiment, the dispersant may be present as a single dispersant. In one embodiment, the dispersant may be present as a mixture of two or three different dispersants, where at least one may be a succinimide dispersant. In an embodiment, the heat transfer fluid may include both a succinimide dispersant and a polyolefin succinate ester dispersant.

[0100] The succinimide dispersant may be derived from an aliphatic amine, a polyamine, a hydroxy-substituted amine, or a mixture thereof. The aliphatic polyamine may be an aliphatic polyamine, such as an ethylene polyamine, a propylene polyamine, a butylene polyamine, or a mixture thereof. In one embodiment, the aliphatic polyamine may be an ethylene polyamine. In one embodiment, the aliphatic polyamine may be selected from the group consisting of ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, polyamine distillation bottoms, and mixtures thereof.

[0101] The succinimide dispersant may be derived from an aromatic amine, an aromatic polyamine, or a mixture thereof. The aromatic amine may have one or more aromatic moieties linked by hydrocarbylene groups and / or heteroatoms. In certain embodiments, the aromatic amine may be a nitro-substituted aromatic amine. Examples of nitro-substituted aromatic amines include 2-nitroaniline, 3-nitroaniline, and 4-nitroaniline (typically 3-nitroaniline). The succinimide dispersant may be derived from 4-aminodiphenylamine or a mixture thereof.

[0102] In one embodiment, the dispersant may be a succinate ester, amide, or ester-amide. For example, the polyolefin succinate ester may be a polyisobutylene succinate ester of pentaerythritol, or a mixture thereof. The polyolefin succinate ester-amide may be a polyisobutylene succinate reacted with an alcohol (such as pentaerythritol) and an amine (a diamine, typically diethylenetriamine).

[0103] In one embodiment, the dispersant may be a hydrocarbyl succinate ester, or an ester-acid mixture. The hydrocarbyl group may be a branched or linear hydrocarbyl group having from 8 to 60 carbon atoms. In one embodiment, the hydrocarbyl succinate ester may be a C10 to C22 hydrocarbyl succinate. Examples include decyl succinate, dodecyl succinate, tetradecyl succinate, hexadecyl succinate, octadecyl succinate, and combinations thereof. The succinate ester may be derived from an aliphatic alcohol, an aliphatic polyol, an amine-substituted aliphatic alcohol, and combinations thereof. Suitable alcohols include N,N-dimethylethanolamine, propanediol, trimethylolpropane, and pentaerythritol.

[0104] The dispersant can be an N-substituted long chain alkenyl succinimide. An example of an N-substituted long chain alkenyl succinimide is polyisobutylene succinimide. Typically, the polyisobutylene from which the polyisobutylene succinic anhydride is derived has a number average molecular weight of 350-5000, or 550-3000, or 750-2500.

[0105] Dispersants may be post-treated by conventional methods by reaction with any of a variety of agents. Among these are boron compounds (such as boric acid), urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids such as terephthalic acid, hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, and phosphorus compounds. In one embodiment, the post-treated dispersant is borated. In one embodiment, the post-treated dispersant may be reacted with a dimercaptothiadiazole. In one embodiment, the post-treated dispersant may be reacted with phosphoric acid or phosphorous acid.

[0106] The boron post-treated dispersant may be present in an amount to deliver from 0 to 500 ppm of boron to the composition, or from 5 to 250 ppm of boron to the composition, or from 10 to 150 ppm of boron, or from 20 to 100 ppm of boron.

[0107] Polyalkenyl Dispersants - PIB Dispersants - Succinate Esters, Amides or Imides - Esters with TAN (oil free) of 3-40 mg KOH / g 5-30, 6-20

[0108] The dispersant may be present from 20 ppm to 10,000 ppm, 50 ppm to 8000 ppm, 100 ppm to 6000 ppm, 200 ppm to 4000 ppm.

[0109] In embodiments, the ratio of dispersant to metal-containing detergent may be from 4:1 to 1:2, or from 3:1 to 1:2, or from 2:1 to 1:2, or from 3:1 to 1:1, or from 2:1 to 1:1, by weight.

[0110] The heat transfer fluid may also include sulfur-free antioxidants, such as ashless antioxidants, more specifically, aminic and / or phenolic antioxidants.

[0111] The amine-based antioxidants include aromatic amines, for example, amines of the following formula: [ka] (In the formula, R 5is a phenyl group, a naphthyl group, or R 7 R can be an aromatic group such as a phenyl group substituted by 6 and R 7 can be independently hydrogen or an alkyl group containing 1 to 24, or 4 to 20, or 6 to 12 carbon atoms. In one embodiment, the aromatic amine antioxidant is an alkylated diphenylamine, such as a nonylated diphenylamine of the formula: [ka] Or it may comprise a mixture of di-nonylated and mono-nonylated diphenylamine.

[0112] The phenolic antioxidant may be a hindered phenolic antioxidant, in which one or both of the ortho positions on the phenol ring may be occupied by a bulky group such as t-butyl. The phenolic antioxidant may be represented by the general formula: [ka] (In the formula, R 4 is an alkyl group containing 1 to 24, or 4 to 18 carbon atoms, and a is an integer from 1 to 5, or 1 to 3, or 2. The phenol may be a butyl-substituted phenol containing 2 or 3 t-butyl groups, for example as shown below: [ka]

[0113] The para position may also be occupied by a hydrocarbyl group or a group bridging two aromatic rings. In certain embodiments, the para position is, for example, [ka] (In the formula, R 3is a hydrocarbyl group such as an alkyl group containing 1 to 18, or 2 to 12, or 2 to 8, or 2 to 6 carbon atoms, where the t-alkyl can be t-butyl).

[0114] In one embodiment, the heat transfer fluid includes an ashless antioxidant. In one embodiment, the ashless antioxidant is a sulfur-free antioxidant. In one embodiment, the ashless antioxidant is an amine-based antioxidant. In another embodiment, the ashless antioxidant is a phenol-based antioxidant. Mixtures of antioxidants may also be used.

[0115] The total amount of antioxidant may be 0.01-5 wt%, or 0.15-4.5 wt%, or 0.2-4 wt%, or 0.05-1 wt%, or 0.1-0.8 wt%, or 0.15-0.6 wt% of the heat transfer fluid.

[0116] The heat transfer fluid may also include a rheology modifier, such as, for example, a high molecular weight polymer. In one embodiment, the polymer may be prepared by polymerizing an α-olefin monomer, or a mixture of α-olefin monomers, or a mixture comprising ethylene and at least one C3-C28 α-olefin monomer, in the presence of a catalyst system comprising at least one metallocene (e.g., a cyclopentadienyl-transition metal compound) and an alumoxane compound.

[0117] Suitable polymers of the olefin polymer class include ethylene propylene copolymers, ethylene-propylene-alpha olefin terpolymers, ethylene-alpha olefin copolymers, ethylene propylene copolymers further containing a non-conjugated diene, and isobutylene / conjugated diene copolymers, each of which may then be provided with grafted carboxyl functionality.

[0118] Ethylene-propylene or higher alpha monoolefin copolymers may consist of 15-80 mole % ethylene and 20-85 mole % propylene or higher monoolefins, in some embodiments the molar ratios are 30-80 mole % ethylene and 20-70 mole % of at least one C3-C10 alpha monoolefin, for example 50-80 mole % ethylene and 20-50 mole % propylene. Terpolymer versions of the foregoing polymers may contain up to 15 mole % non-conjugated dienes or trienes.

[0119] In these embodiments, the polymer substrate, such as an ethylene copolymer or terpolymer, can be an oil-soluble, substantially linear, rubbery material. Also, in certain embodiments, the polymer can be other than substantially linear in form, i.e., a branched or star polymer. The polymer can also be a random or block copolymer, including diblocks and higher order blocks, including tapered blocks and various other structures. These types of polymer structures are known in the art and their preparation is within the capabilities of one of ordinary skill in the art.

[0120] The polymers of the disclosed technology can typically have a number average molecular weight (by gel permeation chromatography, polystyrene standard) that can be 2,000 to 500,000, 10,000 to 300,000, 50,000 to 250,000, or 9,000 to 55,000, or 11,000 to 52,000, or 40,000 to 50,000.

[0121] Another useful class of polymers is constituted by polymers prepared by cationic polymerization of, for example, isobutene or styrene. Typical polymers from this class include polyisobutenes obtained by polymerization of C4 refinery streams having a butene content of 35-75% by mass and an isobutene content of 30-60% by mass in the presence of Lewis acid catalysts such as aluminum trichloride or boron trifluoride, with aluminum trichloride being preferred. A suitable source of monomers for producing poly-n-butenes is a petroleum feed stream such as Raffinate II. These feedstocks are disclosed in the art, such as in U.S. Pat. No. 4,952,739. Polyisobutylene is a suitable polymer for the present invention, since it is readily available from butene streams by cationic polymerization (e.g., using AlCl3 or BF3 catalysts).

[0122] It is known that polyisobutylene can be prepared by cationic polymerization using boron halides, especially boron trifluoride (EP 206756, U.S. Pat. No. 4,316,973, GB 525542 and GB 828367). The polymerization of isobutylene can be controlled to obtain polyisobutylene with number average molecular weights (Mn) much higher than 1,000,000.

[0123] In one embodiment, the olefin polymer is a copolymer of olefins having 4 or more carbon atoms. In one embodiment, the olefin polymer (polyolefin) comprises 50-100% by weight of units derived from at least one olefin monomer having 4 or more carbon atoms. In a typical embodiment, the olefin can be an unsaturated aliphatic hydrocarbon such as butene, isobutylene (or isobutene), butadiene, isoprene, or combinations thereof.

[0124] The polyolefin polymers of the present invention may have a number average molecular weight (gel permeation chromatography, polystyrene standard) of 20,000 to 10,000,000, 100,000 to 1,500,000, or 200,000 to 1,000,000. In other embodiments, the olefin polymer is a polyisobutylene having a number average molecular weight of at least 50,000, at least 100,000, or at least 250,000 up to 850,000, 600,000, or 500,000. Specific ranges include 250,000 to 750,000 or 250,000 to 500,000.

[0125] The polymer may be present in the heat transfer fluid at 0.001-1%, or 0.003-0.8%, or 0.005-0.5%, or 0.01-0.1%, or 0.02%-0.05%, such as 0.003%-0.1%, or even 0.003%-0.01%, by weight. In another embodiment, the polymer additive may be present in the heat transfer fluid at a concentration of 500 parts per million (ppm) or less, or 300 ppm or less, or 100 ppm or less, or 10 ppm to 50 ppm, or even 20-40 ppm. The concentration of the polymer in the heat transfer fluid is measured on an oil-free basis.

[0126] Other conventional additives may also be present, such as antioxidants, corrosion inhibitors, fluoroelastomer seal regenerators, lubricity additives, flow improvers, or any combination thereof. The additional additives may be present in an amount of 0.01 to 2 weight percent, or 0.025 to 2 weight percent, or 0.05 to 1 weight percent, or 0.075 to 0.5 weight percent of the composition.

[0127] 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, flame retardants, metal deactivators, flow additives, corrosion inhibitors, foam inhibitors, demulsifiers, pour point depressants, seal swell 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 multiple packages of performance additives. In one embodiment, the one or more additional additives may be present at 0.01 weight percent to 3 weight percent, or 0.05 weight percent to 1.5 weight percent, or 0.1 weight percent to 1.0 weight percent.

[0128] The thermal management system disclosed herein can remove heat at a rate that allows for rapid charging of the battery. Rapid charging targets include 120-1000 kW. The resulting heat generated during charging and discharging of the battery can generate over 10 kW of heat within the pack.

[0129] The thermal management systems disclosed herein can lubricate a drivetrain, including, for example, a transmission or an electric motor, without electrostatic discharge.

[0130] As used herein, the term "hydrocarbyl" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:

[0131] Hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic, aliphatic, and alicyclic substituted aromatic substituents, as well as cyclic substituents in which the ring is completed through another portion of the molecule (e.g., two substituents taken together form a ring);

[0132] Substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);

[0133] Hetero substituents, i.e., in the context of the present invention, include those that have a predominantly hydrocarbon character but contain other than carbon in a ring or chain otherwise composed of carbon atoms, and include substituents such as pyridyl, furyl, thienyl, and imidazolyl. Heteroatoms include sulfur, oxygen, and nitrogen. There may be no more than two, or no more than one non-hydrocarbon substituent for every 10 carbon atoms in the hydrocarbyl group, and alternatively, there may be no non-hydrocarbon substituents in the hydrocarbyl group.

[0134] It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may differ from those initially added. For example, metal ions (e.g., of detergents) may migrate to other acidic or anionic sites of other molecules. The products formed thereby may not be easily explained, including the products formed when using the composition of the present invention in its intended application. Nevertheless, all such modifications and reaction products are included within the scope of the present invention. The present invention includes the composition prepared by mixing as described above.

[0135] The present invention is useful for cooling electrical components during operation and may be better understood with reference to the following examples. Working Example

[0136] The heat transfer fluids were evaluated for electrical conductivity and dissipation. A series of fluids were prepared with the following additive compositions: [Table 1] 1. Concentrations are in weight percent unless otherwise stated. 2. Alkylbenzene sulfonate, TBN=300mg KOH / g, contains 42% oil 3. Ester of N,N-dimethylethanolamine and hexadecylsuccinic acid 4. Hydroxyalkyl ester of dodecyl succinic acid, containing 37% oil 5. Ester of pentaerythritol and polyisobutenyl succinic acid (PIB Mn 1000 Da), containing 44% oil

[0137] The heat transfer fluids were evaluated for dissipation factor and dielectric constant according to ASTM D924, and volume conductivity according to ASTM D1169, as shown in Tables 2 and 3 below. [Table 2] 1. Kinematic viscosity at 25°C is 2.0m 2 / s isoparaffinic hydrocarbons [Table 3] 1. An isoparaffinic hydrocarbon with a kinematic viscosity of 2.0 cSt at 25°C 2. An isomerized paraffinic base oil with a kinematic viscosity of 10 cSt at 40°C 3. A polyalphaolefin with a kinematic viscosity of 5.1 cSt at 40°C. 4. Propylene glycol dicaprylate 5. Butylated hydroxytoluene

[0138] These data demonstrate that the addition of small concentrations of additives can increase conductivity sufficiently to reduce and mitigate static build-up and prevent destructive discharges through the dielectric thermal fluid.

[0139] Each of the documents mentioned above is incorporated herein by reference, including any prior application to which priority is claimed, whether or not specifically listed above. The reference of any document is not an admission that such document qualifies as prior art or constitutes the general knowledge of the skilled artisan in any jurisdiction. Except in the examples or where otherwise expressly indicated, all quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, should be understood as being modified by the word "about". It should be understood that the upper and lower limits of amounts, ranges, and ratios described herein can be independently combined. Similarly, the ranges and amounts for each element of the present invention can be used together with ranges or amounts for any of the other elements.

[0140] As used herein, the transitional term "comprising," which is synonymous with "including," "containing," or "characterized by," is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. However, in each occurrence 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 element or step, and "consisting essentially of" permits the inclusion of additional, unrecited elements or steps that do not materially affect the essential or basic and novel characteristics of the composition or method under consideration.

[0141] While certain representative embodiments and details have been shown for the purpose of illustrating the present invention, 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, which in this regard should be limited only by the scope of the claims that follow.

Claims

1. A method for cooling an electrical component, comprising: immersing the electrical component in a bath containing a heat transfer fluid comprising a hydrocarbon oil, an overbased metal-containing detergent, and a dispersant; and operating the electrical component.

2. 10. The method of claim 1, wherein the metal-containing detergent comprises a calcium sulfonate detergent.

3. The method of claim 1, wherein the metal-containing detergent is present in the heat transfer fluid at 10 to 5000 ppm.

4. 10. The method of claim 1, wherein the dispersant comprises a hydrocarbyl-substituted succinimide dispersant, a Mannich dispersant, a hydrocarbyl-substituted succinamide dispersant, a hydrocarbyl-substituted succinic ester, amide, ester-amide, and mixtures thereof.

5. The method of claim 1, wherein the dispersant is present in the heat transfer fluid at 20 to 10,000 ppm.

6. 10. The method of claim 1, wherein the ratio of said dispersant to said metal-containing detergent is from 4:1 to 1:2 by weight.

7. The method of claim 1 further comprising an ashless antioxidant.

8. 10. The method of claim 1, wherein the ashless antioxidant is an aminic antioxidant.

9. 10. The method of claim 1, wherein the ashless antioxidant is a phenolic antioxidant.

10. The method of claim 1 , wherein the phenolic antioxidant comprises di-tert-butylphenol.

11. The method of claim 1, wherein the phenolic antioxidant is present in the heat transfer fluid at 0.01 to 5 weight percent.