High thermal conductivity hydrocarbon thermal management fluids for electric vehicles

Abstract

Thermal management fluids and application methods for electrical systems are disclosed. Example thermal management fluids may comprise: a base oil as the main component, wherein the base oil has the following two listed properties: (i) a branching content of about 15 mol% to about 30 mol%; and (ii) a naphthenic content of about 30 wt% or less.

Description

Invention Field

[0001] This disclosure relates to thermal management fluids for electrical components, and particularly to thermal management fluids with high thermal conductivity suitable for use in electric vehicles.

[0002] background

[0003] Thermal management fluids can be used in heat transfer systems for electric vehicles. These fluids can be aqueous solutions that indirectly remove heat generated from specific electrical systems and components. As electric vehicle technology and electrical systems evolve to include longer battery ranges, shorter recharge times, and higher vehicle power, such aqueous thermal management fluids may not provide effective thermal management and heat transfer.

[0004] Direct thermal management can provide effective thermal management of heat generated by hot surfaces. The effectiveness of thermal management fluids can depend on their thermal conductivity. Thermal management fluids with high thermal conductivity can be used in direct thermal management applications to improve thermal management effectiveness and the energy efficiency of the thermal management fluid cycle. However, such electric vehicles and systems can be damaged by direct thermal management with aqueous thermal management fluids, which may include safety issues related to the conductivity of water and the potential risks of hydrogen formation and release. Non-aqueous thermal management fluids, such as hydrocarbon-based heat transfer fluids, mentioned in this disclosure can provide the benefits of both direct thermal management at hot component surfaces and the safety of low conductivity non-aqueous thermal management fluids. For example, such direct immersion cooling can help reduce the risk of uncontrolled thermal runaway within a battery module where one of the battery cells is damaged due to a short circuit or physical damage.

[0005] A thermal management fluid with high thermal conductivity is still required, which effectively maximizes heat removal while minimizing the amount of power required for the thermal management fluid circulation.

[0006] Overview

[0007] This document discloses an example thermal management fluid for electrical systems, comprising a base oil as the main component, wherein the base oil has the following two listed properties: (i) a branch content of about 15 mol% to about 30 mol%; and (ii) a naphthenic content of about 30 wt% or less.

[0008] This document also discloses an example method for cooling an electrical system, comprising circulating a thermal management fluid to contact one or more components of the electrical system to remove heat from the one or more components, wherein the thermal management fluid contains a base oil as a major component, wherein the base oil has the following two listed properties: (i) a branch content of about 15 mol% to about 30 mol%; and (ii) a naphthenic content of about 30 wt% or less.

[0009] Brief description of the attached diagram

[0010] The accompanying drawings illustrate certain aspects of this disclosure, but these should not be used to limit or restrict the scope of this disclosure.

[0011] Figure 1 It is a graph showing the thermal conductivity relative to kinematic viscosity of various hydrocarbon fluid samples.

[0012] Figure 2 It displays the kinematic viscosity of various hydrocarbon fluid samples at 5mm. 2 A graph showing the thermal conductivity relative to the branching content at / s.

[0013] Detailed Explanation

[0014] The following is a detailed description of the disclosure provided to assist those skilled in the art in practicing this disclosure. Those skilled in the art can modify and vary the embodiments described herein without departing from the spirit or scope of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. The terminology used in the description of the disclosure herein is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. All disclosures, patent applications, patents, drawings, and other references mentioned herein are incorporated herein by reference in their entirety.

[0015] The terms “electrical system,” “electrical installation,” “electrical system,” “electrical device,” and any variations thereof mean any system, apparatus, or equipment that is primarily powered or operated by electrical means and requires a heat transfer system to remove generated heat to extend operation. Examples of electrical systems include, but are not limited to, electric vehicles, power electronics included in electric vehicles (e.g., “on-board” electronics), electric motors, batteries, rechargeable battery systems, charging stations, electronic equipment, computers, server racks (or fields), data centers, or any combination thereof.

[0016] "Electric vehicle" and any variations thereof refer to fully electric and completely electric vehicles, as well as hybrid and hybrid electric vehicles, which may have any of a variety of parallel or series drivetrain configurations, individually or in combination, and include mechanical and electrical systems, subsystems, and geared components for use in the vehicle. These mechanical and electrical systems, subsystems, and geared components may include, for example, electric vehicle power systems, powertrain components, drivetrain components, kinetic energy recovery systems (KERS), energy regeneration systems, etc. The terms electric vehicle and hybrid vehicle are used interchangeably. Furthermore, the term "electric vehicle" is not limited to land vehicles (e.g., automobiles), but is also intended to include any type of fully or partially electric vehicle and includes air vehicles (e.g., airplanes, drones, spacecraft, etc.) and marine vehicles (e.g., any type of surface vessel, hovercraft, etc.). "Electric vehicle" may also refer to manually propelled or automated vehicles, or any combination thereof.

[0017] This disclosure relates to thermal management fluids for electrical systems, and in one or more embodiments to shielding methods for suitable liquid thermal management fluids. In electric vehicle applications, the performance of thermal management fluids is controlled by their ability to remove heat from hot surfaces and by the amount of power required to circulate the thermal management fluid. Ideally, a suitable thermal management fluid should maximize heat removal from hot surfaces and minimize the minimum power required to circulate through the system. According to embodiments of this application, thermal management fluids may include base oils and optionally one or more additional additives. These thermal management fluids have thermal, physical, and chemical properties that should allow them to be suitable for thermal management of electrical systems. In this disclosure, the term thermal management fluid includes lubricating oil, lubricating fluid, lubricant, lubricating oil, working fluid, thermal management oil, thermal management fluid, and non-aqueous dielectric coolant; such terms are used interchangeably.

[0018] In implementation, the ability of a thermal management fluid to remove heat from a hot surface is its thermal conductivity. The thermal conductivity of a thermal management fluid is a property that imparts satisfactory thermal management to an electrical system. Heat transfer can occur at a lower rate in fluids with lower thermal conductivity than in materials with higher thermal conductivity. When comparing different families of thermal management fluids, thermal conductivity can increase with fluid flow characteristics such as kinematic viscosity. However, when comparing different thermal management fluids with similar flow characteristics such as kinematic viscosity, thermal conductivity does not represent a direct and definitive correlation with the fluid flow characteristics. However, the fundamental chemical properties of the thermal management fluid can alternatively provide evidence regarding its thermal conductivity.

[0019] As used herein, the term "thermal conductivity" for a thermal management fluid refers to a value measured from the heat flow through the fluid as determined by a method conforming to or derived from ASTM D7896. In some embodiments, the thermal management fluid may have a thermal conductivity at 40°C of about 0.15 W / mK or less, or about 0.14 W / mK or less, or about 0.13 W / mK or less, or about 0.12 W / mK or less. In some embodiments, the thermal management fluid may have a thermal conductivity at 40°C of about 0.1 W / mK to about 0.15 W / mK, or about 0.1 W / mK to about 0.11 W / mK, or about 0.11 W / mK to about 0.13 W / mK, or about 0.12 W / mK to about 0.14 W / mK.

[0020] Various physicochemical properties can exist in thermal management fluids that affect the overall thermal management performance, influencing the effectiveness of heat removal from hot surfaces, such as thermal conductivity. These properties can affect the fluid's thermochemical properties (e.g., heat transfer) or physical properties (e.g., flow characteristics). These thermal management fluid properties may include, but are not limited to, the structural chemistry, branching and cycloalkane content of the thermal management fluid composition, as well as its flow and physical properties.

[0021] The compositions and properties of the present invention can be evaluated independently. A suitable thermal management fluid can satisfy at least one property and at least one composition as disclosed herein.

[0022] Branching content (BC) of the base oil in a thermal management fluid is a property of the hydrocarbon composition of the fluid that can affect its overall thermal management performance in an electrical system. Base oils in thermal management fluids include straight-chain hydrocarbons (where the primary carbon is bonded to only one other carbon atom) or branched chains (where the carbon can be bonded to more than one other carbon). Branched carbons can be secondary, tertiary, or quaternary carbons bonded to two, three, or four other carbons, respectively. As used herein, branching content can also refer to the tertiary carbon content of the base oil in the thermal management fluid. Branching content can be related to the physical properties of the thermal management fluid. The degree and length of branching in the branched hydrocarbons determine the flow properties of the thermal management fluid. Higher degrees and longer branches in the base oil can improve physical properties such as the kinematic viscosity of the thermal management fluid because branching provides greater opportunities for molecular entanglement within the fluid.

[0023] Branching content of base oil in thermal management fluids is calculated based on proton nuclear magnetic resonance (NMR) peak integration, gas chromatography (GC), and alkane / cycloalkane analysis. As used herein, branching content is determined based on the following equation:

[0024]

[0025] Where a is the proton NMR methyl peak integral, b is the proton NMR methine / methylene peak integral, n is the average carbon number determined by GC, and x is the cycloalkane content. The cycloalkane content can be determined by hydrocarbon characterization analysis based on ASTM D2786.

[0026] The branching content of hydrocarbons can be present in any amount suitable for thermal management applications. The branching content of hydrocarbons is measured based on the mole fraction or mol% of hydrocarbons in the thermal management fluid obtained from equation (1). For example, without limitation, the branching content of the base oil in the thermal management fluid can be present at a point ranging from about 15 mol% to about 30 mol%, based on a branching content function. Alternatively, the branching content of the base oil can be present at a point ranging from about 15 mol% to about 25 mol%, at a point ranging from about 15 mol% to about 20 mol%, at a point ranging from about 20 mol% to 30 mol%, or at a point ranging from about 25 mol% to about 30 mol%. Those skilled in the art who benefit from this disclosure should be able to calculate and select an appropriate branching content for the base oil used in the thermal management fluid.

[0027] The kinematic viscosity of a thermal management fluid is a physical property that can affect the overall thermal management performance of an electrical system. As used herein, viscosity is determined according to ASTM D445. Kinematic viscosity is the product of the measured flow time and the calibration constant of the viscometer. Higher flow properties of the thermal management fluid, such as higher kinematic viscosity, require greater power to circulate the fluid through electric vehicles and electrical systems. While higher kinematic viscosity may not necessarily mean higher thermal conductivity for removing heat from hot surfaces, it is important to consider the kinematic viscosity of the thermal management fluid to ensure proper circulation on the system.

[0028] As used herein, the term "kinematic viscosity at 40°C" or "KV40" for a thermal management fluid refers to the kinematic viscosity at 40°C as measured according to ASTM D445. In some embodiments, the thermal management fluid may have a KV40 of about 15 centistokes (cSt) or less, or about 8 cSt or less, or about 6 cSt or less, or about 4 cSt or less, or about 2 cSt or less. In some embodiments, the thermal management fluid may have a KV40 of about 1 cSt to about 5 cSt, or about 2 cSt to about 4 cSt, or about 5 cSt to about 10 cSt, or about 1 cSt to 15 cSt. In some embodiments, the thermal management fluid may have a KV40 of about 15 mm... 2 / s or less, or about 8mm 2 / s or less, or about 6mm 2 / s or less, or about 4mm 2 / s or less, or about 2mm 2 / s or less KV40. In some implementations, the thermal management fluid may have a density of approximately 1 mm.2 / s to approximately 5mm 2 / s, or approximately 2mm 2 / s to approximately 4mm 2 / s, or approximately 5mm 2 / s to approximately 10mm 2 / s, or approximately 1mm 2 / s to 15mm 2 / s of KV40.

[0029] The cycloalkane content of a thermal management fluid is a property that can affect the overall thermal management performance of an electrical system. As used herein, the cycloalkane content can be determined by hydrocarbon characterization analysis according to ASTM D2786. Various techniques, including but not limited to proton nuclear magnetic resonance (NMR), gas chromatography (GC), and spectroscopic methods, can provide information about the specified components in the thermal management fluid. In some embodiments, the thermal management fluid may have a cycloalkane content of less than or equal to 30 wt%, or less than or equal to 25 wt%, or less than or equal to 20 wt%, or less than or equal to 15 wt%, or less than or equal to 10 wt%, or less than or equal to 5 wt%.

[0030] The density of the thermal management fluid can be another fluid property that imparts satisfactory heat transfer performance to an electrical system. As used herein, the density can be determined according to ASTM D4052. In some embodiments, at a temperature of 40°C, the thermal management fluid may have a density of about 0.25 g / mL to about 1.75 g / mL, or about 0.30 g / mL to about 1.70 g / mL, or about 0.35 g / mL to about 1.65 g / mL, or about 0.40 g / mL to about 1.60 g / mL, or about 0.45 g / mL to about 1.55 g / mL. In another embodiment, at a temperature of 80°C, the thermal management fluid may have a density of about 0.25 g / mL to about 1.75 g / mL, or about 0.30 g / mL to about 1.70 g / mL, or about 0.35 g / mL to about 1.65 g / mL, or about 0.40 g / mL to about 1.60 g / mL, or about 0.45 g / mL to about 1.55 g / mL.

[0031] The specific heat of a thermal management fluid can be another fluid property that imparts satisfactory heat transfer performance to an electrical system. As used herein, specific heat can be determined according to ASTM E1269. In some embodiments, at a temperature of 40°C, the thermal management fluid may have a specific heat of about 1.25 kJ / kg·K to about 3.50 kJ / kg·K, or about 1.35 kJ / kg·K to about 3.40 kJ / kg·K, or about 1.45 kJ / kg·K to about 3.25 kJ / kg·K, or about 1.50 kJ / kg·K to about 3.20 kJ / kg·K, or about 1.55 kJ / kg·K to about 3.15 kJ / kg·K. In another embodiment, at a temperature of 80°C, the thermal management fluid may have a specific heat of about 1.25 kJ / kg·K to about 3.50 kJ / kg·K, or about 1.35 kJ / kg·K to about 3.40 kJ / kg·K, or about 1.45 kJ / kg·K to about 3.25 kJ / kg·K, or about 1.50 kJ / kg·K to about 3.20 kJ / kg·K, or about 1.55 kJ / kg·K to about 3.15 kJ / kg·K.

[0032] The dynamic viscosity of a thermal management fluid can be another fluid property that imparts satisfactory heat transfer performance to an electrical system. As used herein, dynamic viscosity can be determined according to ASTM E1269, where the kinematic viscosity is multiplied by the density at a given temperature. In some embodiments, where the average fluid temperature can be 40°C, the thermal management fluid can have a dynamic viscosity of about 0.50 centipoise (cP) to about 7.50 cP, or about 0.55 cP to about 7.00 cP, or about 0.65 cP to about 6.50 cP, or about 0.70 cP to about 6.00 cP, or about 0.75 cP to about 5.50 cP. In another embodiment, when the average fluid temperature is 80°C, the thermal management fluid may have a dynamic viscosity of about 0.50 cP to about 7.50 cP, or about 0.55 cP to about 7.00 cP, or about 0.65 cP to about 6.50 cP, or about 0.70 cP to about 6.00 cP, or about 0.75 cP to about 5.50 cP.

[0033] The thermal management fluids mentioned herein provide durable thermal management fluid properties throughout their lifespan, as well as compatibility with the electrical systems mentioned herein, such as electric vehicles and their components and materials. Illustrative electrical systems and electric vehicle components that can be cooled according to this disclosure include, for example, electric vehicle batteries, electric motors, electric generators, AC-DC / DC-AC / AC-AC / DC-DC converters, AC-DC / DC-AC / AC-AC / DC-DC transformers, power management systems, electronic control batteries, on-board chargers, on-board power electronics, ultra-fast charging systems, fast charging equipment at charging stations, stationary ultra-fast chargers, etc.

[0034] Depending on the specific electrical system (e.g., electric vehicle batteries, electric motors, electric generators, AC-DC / DC-AC / AC-AC / DC-DC converters, AC-DC / DC-AC / AC-AC / DC-DC transformers, power management systems, electronic control batteries, on-board chargers, on-board power electronics, ultra-fast charging systems, fast charging equipment at charging stations, stationary ultra-fast chargers, etc.), the electrical system can operate over a wide temperature range. For example, the electrical system can operate at temperatures between about -40°C and about 175°C, or between about -25°C and about 170°C, or between about -10°C and about 165°C, or between about 0°C and about 160°C, or between about 10°C and about 155°C, or between about 25°C and about 150°C, or between about 25°C and about 125°C, or between about 30°C and about 120°C, or between about 35°C and about 115°C, or between about 35°C and about 105°C, or between about 35°C and about 95°C, or between about 35°C and about 85°C.

[0035] In one embodiment, a single thermal management fluid may be used in the electrical system. In another embodiment, more than one thermal management fluid may be used in the electrical system, for example, one thermal management fluid for the battery and another thermal management fluid for another component of the electrical system.

[0036] The thermal management fluids mentioned in this article provide thermal management on surfaces including, for example, those of the following equipment components: metals, metal alloys, nonmetals, nonmetal alloys, mixed carbon-metal composites and alloys, mixed carbon-nonmetal composites and alloys, ferrous metals, ferrous composites and alloys, non-ferrous metals, non-ferrous metal composites and alloys, titanium, titanium composites and alloys, aluminum, aluminum composites and alloys, magnesium, magnesium composites and alloys, ion-implanted metals and alloys, plasma-modified surfaces; surface-modified materials; coatings; single-layer, multi-layer, and gradient-layered coatings; ground surfaces; polished surfaces; etched surfaces; textured surfaces; micron and nanostructures on textured surfaces; ultra-precision machining. Surfaces; diamond-like carbon (DLC), DLC with high hydrogen content, DLC with medium hydrogen content, DLC with low hydrogen content, DLC with near-zero hydrogen content, DLC composites, DLC-metal compositions and composites, DLC-nonmetal compositions and composites; ceramics, ceramic oxides, ceramic nitrides, FeN, CrN, ceramic carbides, mixed ceramic compositions, etc.; polymers, thermoplastic polymers, engineering polymers, polymer blends, polymer alloys, polymer composites; material compositions and composites, including, for example, graphite, carbon, molybdenum, molybdenum disulfide, polytetrafluoroethylene, perfluoropropylene, perfluoroalkyl ethers, etc.

[0037] As previously described, thermal management fluids can be used for thermal management of electrical systems according to this embodiment. The thermal management fluids disclosed herein provide durable thermal management fluid properties and compatibility with the electrical systems mentioned herein, such as electric motors, electric vehicles, and their corresponding components and materials, throughout their lifespan. Illustrative electrical system components that can be cooled according to this disclosure include, for example, batteries, electric motors, electric generators, AC-DC / DC-AC / AC-AC / DC-DC converters, AC-DC / DC-AC / AC-AC / DC-DC transformers, power management systems, electronic control batteries, on-board chargers, on-board power electronics, ultra-fast charging systems, fast charging equipment at charging stations, stationary ultra-fast chargers, etc.

[0038] Depending on the specific electrical system (e.g., battery, motor, electric generator, AC-DC / DC-AC / AC-AC / DC-DC converter, AC-DC / DC-AC / AC-AC / DC-DC transformer, power management system, electronic control battery, on-board charger, on-board power electronics, ultra-fast charging system, fast charging equipment at charging stations, stationary ultra-fast charger, etc.), the electrical system can operate over a wide temperature range. For example, the electrical system can operate at temperatures between about -40°C and about 175°C, or between about -25°C and about 170°C, or between about -10°C and about 165°C, or between about 0°C and about 160°C, or between about 10°C and about 155°C, or between about 25°C and about 150°C, or between about 25°C and about 125°C, or between about 30°C and about 120°C, or between about 35°C and about 115°C, or between about 35°C and about 105°C, or between about 35°C and about 95°C, or between about 35°C and about 85°C.

[0039] In one implementation, a single thermal management fluid may be used in the electrical system. In another implementation, more than one thermal management fluid may be used in the electrical system, for example, one thermal transfer fluid for the battery and another thermal transfer fluid for another component of the electrical system.

[0040] The thermal management fluids mentioned in this article can be used on surfaces including, for example, those of the following equipment components: metals, metal alloys, non-metals, non-metal alloys, mixed carbon-metal composites and alloys, mixed carbon-nonmetal composites and alloys, ferrous metals, ferrous composites and alloys, non-ferrous metals, non-ferrous metal composites and alloys, titanium, titanium composites and alloys, aluminum, aluminum composites and alloys, magnesium, magnesium composites and alloys, ion-implanted metals and alloys, plasma-modified surfaces; surface-modified materials; coatings; single-layer, multi-layer, and gradient-layered coatings; ground surfaces; polished surfaces; etched surfaces; textured surfaces; micron and nanostructures on textured surfaces; ultra-precision machining. Surfaces; diamond-like carbon (DLC), DLC with high hydrogen content, DLC with medium hydrogen content, DLC with low hydrogen content, DLC with near-zero hydrogen content, DLC composites, DLC-metal compositions and composites, DLC-nonmetal compositions and composites; ceramics, ceramic oxides, ceramic nitrides, FeN, CrN, ceramic carbides, mixed ceramic compositions, etc.; polymers, thermoplastic polymers, engineering polymers, polymer blends, polymer alloys, polymer composites; material compositions and composites, including, for example, graphite, carbon, molybdenum, molybdenum disulfide, polytetrafluoroethylene, perfluoropropylene, perfluoroalkyl ethers, etc.

[0041] In some embodiments, the electrical system may include an oil thermal management system. Examples of an oil thermal management system may include one or more conduits and a pump configured to circulate thermal management fluid through the one or more conduits. The pump may include, for example, a positive displacement pump or a centrifugal pump. The thermal management fluid may include any thermal management fluid disclosed herein and may be used to cool electrical system components (e.g., electric motors, batteries) that form part of the electrical system. In some embodiments, the thermal management fluid may be configured to directly cool one or more surfaces of the electrical system components, thereby removing heat from the electrical system components. After exchanging heat with the electrical system components, the warm thermal management fluid at an elevated temperature may be transported away from the electrical system components 108. The warm thermal management fluid may then be transported within the conduits(one or more) to a heat exchanger included in the oil thermal management system. The heat exchanger may operate similarly to a radiator, removing heat from the warm thermal management fluid. In some embodiments, the heat exchanger may, for example, dissipate heat to another fluid or air at ambient temperature. The heat exchanger may be a specific device, or the heat transfer fluid may simply lose heat to the atmosphere as it flows through the conduits(one or more). The thermal management fluid may then be recirculated to the electrical system components. These descriptions of the electric coolant system are merely examples, and the thermal management fluid can be used with any suitable thermal management system for the thermal management of electrical system components.

[0042] One or more embodiments of an oil thermal management system may include circulating thermal management fluid in contact with one or more components of an electrical system, such as a battery or motor. The thermal management fluid can absorb heat from the electrical system components, thereby cooling the electrical system components through heat removal. Suitable oil thermal management systems may include surface thermal management and / or internal thermal management of the motor. One or more embodiments of an oil thermal management system using surface thermal management may circulate the thermal management fluid through a thermal management sheath outside the motor stator. One or more embodiments of an oil thermal management system using internal thermal management may circulate the thermal management fluid through electrical system components. By circulating through electrical system components such as the motor, the thermal management fluid can act as a supplement to thermal management, lubricating electrical system components (e.g., motor bearings). In some embodiments, surface and internal thermal management technologies may be combined. However, it should be understood that these descriptions of thermal management technologies are merely examples, and thermal management fluids may be used in accordance with other technologies for the thermal management of motors.

[0043] base oil

[0044] Example implementations of thermal management fluids may include one or more base oils. Suitable base oils may be used, such as alkanes, alkanes, synthetic oils, and unconventional oils, or mixtures thereof. Unrefined, refined, or re-refined (the latter also referred to as regenerated or reprocessed) oils may be used. Unrefined oils are those obtained directly from natural or synthetic sources and used without additional purification. These include shale oils obtained directly from carbonization operations, petroleum oils obtained directly from primary distillation, and ester oils obtained directly from esterification processes. Refined oils are similar to those discussed with regard to unrefined oils, except that refined oils undergo one or more purification steps to improve the properties of at least one thermal management fluid base oil. Many purification processes will be familiar to those skilled in the art. These processes include solvent extraction, double distillation, acid extraction, alkali extraction, filtration, and percolation. Re-refined oils are obtained by methods similar to those used for refined oils, but using previously used oils as feedstock.

[0045] Synthetic oils include oils such as polymerized and interpolymerized olefins (e.g., polybutene, polypropylene, propylene-isobutylene copolymers, ethylene-olefin copolymers, and ethylene-α-olefin copolymers). Polyalphaolefin (PAO) oil base stocks are commonly used synthetic hydrocarbon oils. By way of example, C8, C... 10 C 12 C 14 PAOs are olefins or mixtures thereof. PAOs may include relatively low molecular weight hydrogenated polymers or oligomers of α-olefins, including but not limited to C2 to about C10. 32 α-olefins and C8 to approximately C 16α-olefins, such as 1-octene, octene, 1-decene, decene, 1-dodecene, etc. Suitable examples of polyα-olefins are poly-1-octene, poly-1-decene, and poly-1-dodecene, and mixtures thereof, as well as mixed olefin-derived polyolefins. However, polyolefins derived from C... 14 -C 18 Dimers of higher olefins within a range are used to provide low-viscosity base oils with acceptablely low volatility. Depending on the viscosity grade and starting oligomer, PAO can be primarily trimers and tetramers of the starting olefin, with a small amount of higher oligomers. Exemplary PAO trimers and tetramers may include, but are not limited to, octene trimers, decene trimers, etc., and may have a viscosity range of 1.5 cSt to 14 cSt. If desired, mixtures of PAO fluids with a viscosity range of 1.5 cSt to approximately 350 cSt or greater can be used. In some embodiments, PAO may have a viscosity of approximately 1.5 cSt. 2 / s to approximately 14mm 2 KV40 range per second.

[0046] PAO fluids can be conventionally prepared by polymerizing α-olefins in the presence of a polymerization catalyst such as Friedel-Crafts catalysts (including, for example, aluminum trichloride, boron trifluoride or a complex of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate).

[0047] Base oils may also include alkanes. Alkanes can occur as acyclic, straight-chain, or branched polymer chains of alkanes. Alkanes can originate from C14-C2 ... 10 -C 20 Hydrocarbons or C 16 -C 20 Alkanes are hydrocarbons. Alkanes can have functional groups such as alkyl functional groups. In particular, the alkyl functional group can be a methyl group and the alkane can be a methyl alkane. Alkanes or alkanes can have very low sulfur and nitrogen content, containing less than about 10 ppm or less than about 5 ppm of each of these elements.

[0048] Base oils may also include hydrocarbon fluids. Hydrocarbon fluids may include, but are not limited to, hydrocarbons such as n-alkanes and isoalkanes, cycloalkanes, and any combinations thereof. Hydrocarbon fluids may be derived from C 12 -C 16 Hydrocarbons, or C 13 -C 18 Hydrocarbons, C 14 -C 20 Hydrocarbons, C 14 -C 25Hydrocarbons and any combination thereof. n-Alkanes and iso-alkanes can also be purified by hydrogenation processes to produce low-odor, low-aromatic hydrocarbon fluids. The aromatic content of the alkane fluid can be from about 0.01% by weight to about 3% by weight of the hydrocarbon fluid, or can be less than about 2% by weight of the hydrocarbon fluid. Alkanes can include hydrocarbon chains, which can be saturated and unsaturated, and can be linear and branched. Cycloalkanes can include a group of cyclic hydrocarbons. Hydrocarbon fluids containing a mixture of all three types of hydrocarbons can include straight-chain and cyclic hydrocarbons. Hydrocarbon fluids can have low sulfur and nitrogen content, containing less than about 10 ppm or less than about 5 ppm of each of these elements.

[0049] The base oil may constitute the main component of the thermal management fluid of this disclosure and may be present in an amount ranging from about 50% to about 100% by weight, for example, about 70% to about 90% by weight, or about 85% to about 95% by weight, or about 85% to about 99% by weight, or about 90% to about 100% by weight, based on the total weight of the thermal management fluid.

[0050] The thermal conductivity and kinematic viscosity of the base oil can be measured to determine its suitability as a thermal management fluid. As a supplement to the previously discussed, the branching content can be established at 5mm. 2 Thermal conductivity regression model at / s. At 5mm 2 Thermal conductivity (TC) at / s can be linearly regressed based on (1) thermal conductivity measurements from 0°C to 100°C by means of ASTM D7896 or a similar method derived from ASTM D7896, and (2) kinematic viscosity calculated by means of ASTM D341 at 5 mm. 2 / s temperature, based on kinematic viscosity measurements at 40℃ and 100℃. Figure 2 Illustrate an exemplary model for regression.

[0051] From the regression model, the following equation can be used to calculate the value at 5mm. 2 Predicted thermal conductivity at / s:

[0052] TC Pred =84.873*(BC) -0.17

[0053] Equation (2)

[0054] Among them, in 5mm 2 Predicted thermal conductivity (TC) at / s Pred The branch content, measured in mW / mK, and BC are calculated from Equation 1. From the predicted thermal conductivity and the measured thermal conductivity (TC), the content in 5 mm can be calculated using the following equation. 2 The deviation of thermal conductivity at / s (TC) Dev ):

[0055]

[0056] Equation (3)

[0057] Among them, in 5mm 2 The deviation of thermal conductivity at / s (TC) Dev () is a percentage, TC is in 5mm 2 The measured thermal conductivity and TC of the fluid at / s Pred It is at 5mm 2 Predicted thermal conductivity at / s.

[0058] Other additives

[0059] The thermal management fluid may also include one or more other additives, such as those used in engine oils. These other additives may include any one or more antioxidants, viscosity modifiers, friction modifiers, anti-wear additives, detergents, pour point inhibitors, corrosion inhibitors, rust inhibitors, metal passivators, sealant compatibility additives, and defoamers. Antioxidants may include, but are not limited to, phenol-based and amine-based antioxidants and combinations thereof. Phenolic-based antioxidants may be present in an amount of about 0.25% by weight to about 0.5% by weight, or in an amount greater than or equal to 0.5% by weight, of the thermal management fluid. Amine-based antioxidants may be present in an amount of about 0.1% by weight to about 0.2% by weight, or in an amount greater than or equal to 0.2% by weight, of the thermal management fluid.

[0060] Therefore, the foregoing description describes a thermal management fluid with high thermal conductivity for use in electrical components. The aforementioned thermal management fluid may also include any one or more of the following embodiments:

[0061] Implementation Scheme 1. A thermal management fluid for an electrical system, comprising: a base oil as the main component, wherein the base oil has the following two listed properties: (i) a branch content of about 15 mol% to about 30 mol%; and (ii) a naphthenic content of about 30 wt% or less.

[0062] Implementation Scheme 2. Thermal management fluid of Implementation Scheme 1, wherein the electrical system is part of an electric vehicle.

[0063] Implementation Scheme 3. Thermal management fluid of Implementation Scheme 1 or 2, wherein the electrical system includes an electric motor.

[0064] Implementation Scheme 4. Thermal management fluid of Implementation Scheme 1-3, wherein the electrical system includes a battery.

[0065] Implementation Scheme 5. The thermal management fluid of any one of Implementation Schemes 1-4, wherein the fluid is in direct contact with one or more electrified components of the electrical system to remove heat from the one or more electrified components.

[0066] Implementation Scheme 6. The thermal management fluid of any one of Implementation Schemes 1-5, wherein the base oil has a thickness of approximately 15 mm. 2 / s or smaller KV40.

[0067] Implementation Scheme 7. The heat management fluid of any one of Implementation Schemes 1-6, wherein the branch content of the base oil is from about 15 mol% to about 25 mol%.

[0068] Implementation Scheme 8. The thermal management fluid of any one of Implementation Schemes 1-7, wherein the naphthenic content of the base oil is about 25% by weight or less.

[0069] Implementation Scheme 9. The thermal management fluid of any one of Implementation Schemes 1-8, wherein the thermal management fluid has a 5mm... 2 At a kinematic viscosity of approximately 110 mW / mK or greater, the thermal conductivity is also approximately 110 mW / mK.

[0070] Implementation Scheme 10. The thermal management fluid of any one of Implementation Schemes 1-9, wherein the thermal management fluid has a 5mm... 2 Thermal conductivity at kinematic viscosity / s that is at least about 3% greater than the thermal conductivity predicted by the equation: TC Pred =84.873*(BC) -0.17 TC Pred The predicted thermal conductivity is measured in mW / mK, and BC is the branch content of the thermal management fluid.

[0071] Implementation Scheme 11. The thermal management fluid of any one of Implementation Schemes 1-10, wherein the thermal management fluid has a 5mm... 2 Thermal conductivity at kinematic viscosity / s that is at least about 5% greater than the thermal conductivity predicted by the equation: TC Pred =84.873*(BC) -0.17 TC Pred The predicted thermal conductivity is measured in mW / mK, and BC is the branch content of the thermal management fluid.

[0072] Implementation Scheme 12. The thermal management fluid of any one of Implementation Schemes 1-11 further comprises one or more additives selected from the following: antioxidants, corrosion inhibitors, defoamers, anti-wear agents, dispersants, detergents, viscosity modifiers, and any combination thereof.

[0073] Implementation Scheme 13. The thermal management fluid of any one of Implementation Schemes 1-12 further comprises: at least one phenol-based antioxidant present in an amount of about 0.25% by weight or more, and at least one amine-based antioxidant present in an amount of about 0.1% by weight or more.

[0074] Implementation Scheme 14. The thermal management fluid of any one of Implementation Schemes 1-13 further comprises: at least one phenol-based antioxidant present in an amount of about 0.5% by weight or more, and at least one amine-based antioxidant present in an amount of about 0.2% by weight or more.

[0075] Implementation Scheme 15. A method for cooling an electrical system, comprising: circulating a thermal management fluid to contact one or more components of the electrical system to remove heat from the one or more components, wherein the thermal management fluid contains a base oil as a major component, wherein the base oil has two of the listed properties: (i) a branch content of about 15 mol% to about 30 mol%; and (ii) a naphthenic content of about 30% or less.

[0076] Implementation Scheme 16. The method of Implementation Scheme 15, wherein the electrical system is part of an electric vehicle.

[0077] Implementation Scheme 17. The method of Implementation Scheme 15 or 16, wherein one or more components include an electric motor.

[0078] Implementation Scheme 18. The method of Implementation Scheme 15-17, wherein one or more components include a battery.

[0079] Implementation Scheme 19. The method of any one of Implementation Schemes 15-18, wherein the contact is direct contact with the electrical system to which heat is to be removed.

[0080] Implementation Scheme 20. The method of any one of Implementation Schemes 15-19, wherein the circulation further includes circulating the thermal management fluid through a heat exchanger after the thermal management fluid has come into contact with one or more components of the electrical system to remove heat from the cooling fluid.

[0081] Implementation Scheme 21. The method of any one of Implementation Schemes 15-20, wherein the thermal management fluid has a 5 mm 2 Thermal conductivity at kinematic viscosity / s that is at least about 3% greater than the thermal conductivity predicted by the equation: TC Pred =84.873*(BC) -0.17 TC Pred The predicted thermal conductivity is measured in mW / mK, and BC is the branch content of the thermal management fluid.

[0082] Implementation Scheme 22. The method of any one of Implementation Schemes 15-21 further includes one or more additives selected from the following: antioxidants, corrosion inhibitors, defoamers, anti-wear agents, dispersants, detergents, viscosity modifiers, and any combination thereof.

[0083] Implementation Scheme 23. The method of any one of Implementation Schemes 15-22 further includes: at least one phenol-based antioxidant present in an amount of about 0.25% by weight or more, and at least one amine-based antioxidant present in an amount of about 0.1% by weight or more.

[0084] Implementation Scheme 24. The method of any one of Implementation Schemes 15-23 further includes: at least one phenol-based antioxidant present in an amount of about 0.5% by weight or more, and at least one amine-based antioxidant present in an amount of about 0.2% by weight or more.

[0085] Implementation Scheme 25. The method of any one of Implementation Schemes 15-24, wherein the base oil has a thickness of approximately 15 mm. 2 / s or less of KV40, about 15 mol% to about 25 mol% of branching content and about 25 wt% or less of cycloalkane content. Example

[0086] To facilitate a better understanding of the invention, the following embodiments of certain aspects of some implementations are provided. These embodiments should not in any way be construed as limiting or restricting the entire scope of the invention.

[0087] Example 1

[0088] This example illustrates the correlation between thermal conductivity and kinematic viscosity of various samples of unconventional hydrocarbon fluids, with thermal conductivity serving as a measure of the suitability of the thermal management fluid. The kinematic viscosity of the thermal management fluid samples was measured according to ASTM D445. The thermal conductivity of the thermal management fluid samples was measured according to ASTM D7896, etc.

[0089] Table 1 summarizes the sampled thermal management fluids based on descriptions of similar chemical properties. The sample group includes thermal management fluids containing alkanes, hydrogenated trimers, polyalphaolefins, and hydrocarbon fluids.

[0090] Table 1. Chemical description of non-aqueous hydrocarbon thermal management fluid samples.

[0091]

[0092] Figure 1 The results of this embodiment are explained. A graphical comparison is generated, enabling the comparison of sampled thermal management fluids with different viscosities. For example... Figure 1 The study indicates that samples with the same chemical properties and chemical descriptions tend to have higher thermal conductivity as kinematic viscosity increases.

[0093] Example 2

[0094] The thermal management fluid sampled from Example 1 was further narrowed down to a sample group based on similar kinematic viscosity. Within a similar kinematic viscosity range, the general correlation between kinematic viscosity and thermal conductivity was compared. However, the sample with the highest kinematic viscosity in the sample group was not necessarily the sample with the highest thermal conductivity. Branching content, another property of the sampled thermal management fluid, was used as a comparison to determine a measure of high thermal conductivity. Examples also include predicted thermal conductivity and deviations from the predicted thermal conductivity.

[0095] In Table 2, approximately 2mm is used. 2 / s to approximately 4mm 2 Kinematic viscosity analysis was performed on a group of sampled thermal management fluids. In contrast, while sample 6 had the highest kinematic viscosity, it did not have the highest thermal conductivity. Sample 4 had the highest thermal conductivity but the lowest branching content and no cycloalkane content.

[0096] Table 2. Branching content of thermal management fluids for samples with similar kinematic viscosity at 40°C.

[0097]

[0098] In Table 3, approximately 5mm is used. 2 / s to approximately 6mm 2 Kinematic viscosity analysis of a group of sampled thermal management fluids. Although Sample 1 (methylalkanes) had the lowest kinematic viscosity, Sample 1 also had the highest thermal conductivity. Sample 1 also had the lowest branching content and no cycloalkane content.

[0099] Table 3. Branching content of thermal management fluids for samples with similar kinematic viscosity at 40°C.

[0100]

[0101] In Table 4, the sampled thermal management fluid has a diameter of approximately 7 mm. 2 / s to approximately 8mm 2 The kinematic viscosity is / s. Sample 5 has high thermal conductivity but low branching content and no cycloalkane content.

[0102] Table 4. Branching content of thermal management fluids for samples with kinematic viscosity at 40°C.

[0103]

[0104] In Table 5, the sampled thermal management fluid has a diameter greater than 8 mm. 2 The kinematic viscosity is / s. In comparison, Sample 2 has a higher kinematic viscosity and higher thermal conductivity than Sample 8. Sample 2 also has a lower branching content and no cycloalkane content.

[0105] Table 5. Branching content of thermal management fluids for samples with similar kinematic viscosity at 40°C.

[0106]

[0107] Example 3

[0108] Example analysis of 5mm fluid sample 2 Thermal conductivity and branching content were measured at / s. A regression model was established to calculate the predicted thermal conductivity based on the branching content. Figure 2 This illustrates the results of this embodiment. Table 6 summarizes the results from this embodiment. Figure 2 The calculated predicted thermal conductivity data. The deviation between the predicted and measured thermal conductivity ranges from approximately -5% to approximately 10%.

[0109] Table 6. Thermal conductivity and thermal conductivity deviation of the sample thermal management fluid predicted by branch content.

[0110]

[0111] While this disclosure has described numerous embodiments and examples, those skilled in the art who benefit from it will appreciate that other embodiments can be designed without departing from the scope and spirit of the invention as disclosed herein. Although individual embodiments have been discussed, the invention covers all combinations of all such embodiments.

[0112] When providing ranges of values, it should be understood that unless the context explicitly specifies otherwise (e.g., in the case of providing a group containing a large number of carbon atoms, where the number of carbon atoms falls within the range in each case), each intermediate value between the upper and lower limits of the range up to one-tenth of the unit of the lower limit, and any other stated values ​​or intermediate values ​​within the range, are included in the disclosure. The upper and lower limits of these smaller ranges may be independently included within the smaller ranges, subject to any explicitly excluded boundaries within the range. When the range includes one or two boundaries, the range excluding any one or both of those included boundaries is also included in the disclosure.

[0113] It should also be understood that, unless the contrary is expressly stated otherwise, in any method claimed herein that includes more than one step or action, the order of steps or actions of the method need not be restricted to the order in which the steps or actions of the method are described.

[0114] The following terms are used to describe the contents of this disclosure. Unless otherwise specified herein, each term is assumed by those skilled in the art to have its generally accepted meaning, and is applied in the context in which it is used to describe the contents of this disclosure.

[0115] The articles “a” and “an” as used herein and in the appended claims are used to refer to one or more (i.e., at least one) grammatical objects of that article, unless the context clearly indicates otherwise. By way of example, “element” means one or more elements.

[0116] The phrase “and / or” as used herein in the specification and claims should be understood to mean “any one or both” of the elements thus combined, i.e., elements that exist in combination in some cases and separately in others. Multiple elements listed with “and / or” should be interpreted in the same way, i.e., “one or more” of the elements thus combined. In addition to the elements specifically indicated by the “and / or” clause, other elements may optionally exist, whether related to or unrelated to those specifically indicated. Thus, as a non-limiting example, when used with open-ended language such as “comprising,” reference to “A and / or B” may, in one embodiment, refer only to A (optionally including elements other than B); in another embodiment, refer only to B (optionally including elements other than A); in yet another embodiment, refer to both A and B (optionally including other elements); and so on.

[0117] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when items are separated in a list, “or” or “and / or” should be interpreted as inclusive, that is, including at least one of a plurality or series of elements, but also including more than one, and optionally, including additional items not listed. Only terms that expressly specify the opposite, such as “only one” or “exactly one”, or when used in the claims, “consisting of…” will refer to including exactly one of a plurality or series of elements. Generally, when the term “or” is preceded by an exclusive term, such as “any,” “one of,” “only one,” or “exactly one,” the term “or” as used herein should be interpreted only as indicating an exclusive substitution (i.e., “one or the other, but not both”).

[0118] The terms “about” or “approximately” mean an acceptable experimental error for a particular value as determined by one of ordinary skill in the art, depending in part on how the value is measured or determined. All numerical values ​​in this specification and claims are modified by the value indicated by “about” or “approximately” and take into account experimental errors and deviations expected by one of ordinary skill in the art.

[0119] The phrase "major amount" or "major component" when referring to a component included in the thermal management fluid of the specification and claims means greater than or equal to 50 wt%, or greater than or equal to 60 wt%, or greater than or equal to 70 wt%, or greater than or equal to 80 wt%, or greater than or equal to 90 wt%, based on the total weight of the thermal management fluid. The phrase "minor amount" or "minor component" when referring to a component included in the thermal management fluid of the specification and claims means less than 50 wt%, or less than or equal to 40 wt%, or less than or equal to 30 wt%, or greater than or equal to 20 wt%, or less than or equal to 10 wt%, or less than or equal to 5 wt%, or less than or equal to 2 wt%, or less than or equal to 1 wt%, based on the total weight of the thermal management fluid. The phrase “substantially free of” or “essentially free of” when referring to components included in the thermal management fluid of the specification and claims means that a particular component is present in the lubricating oil at 0% by weight, or alternatively at an impurity level (less than 100 ppm, or less than 20 ppm, or less than 10 ppm, or less than 1 ppm).

[0120] In the claims and in the above description, all conjunctions such as “comprising,” “including,” “with,” “having,” “containing,” “involving,” “holding,” “comprising,” etc., should be understood as open-ended, meaning including but not limited to. Only the conjunctions “composed of…” and “substantially composed of…” should be closed or semi-closed conjunctions, respectively.

[0121] As used herein in the specification and in the claims, with respect to a list of one or more elements, the phrase “at least one” should be understood to mean that at least one element is selected from any one or more elements in the list of elements, but does not necessarily include at least one of all elements specifically listed in the list of elements, and does not exclude any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than those specifically indicated in the list of elements referred to by the phrase “at least one”, whether related to or unrelated to those specifically indicated elements. Thus, as a non-limiting example, “at least one of A and B” (or equivalently “at least one of A or B”, or equivalently “at least one of A and / or B”) may refer to at least one, optionally including more than one A, without B (and optionally including elements other than B) in one embodiment; at least one, optionally including more than one B, without A (and optionally including elements other than A) in another embodiment; at least one, optionally including more than one A, and at least one, optionally including more than one B (and optionally including other elements); and so on.

Claims

1. A thermal management fluid for electrical systems, comprising: a base oil as the main component, wherein the base oil has the following two listed properties: (i) a branching content of 20 mol% to 30 mol% which is the tertiary carbon content of the base oil; and (ii) a naphthenic content of 30 wt% or less. The thermal management fluid has a 5mm... 2 Thermal conductivity at a kinematic viscosity of / s that is at least 5% greater than the thermal conductivity predicted by the following regression model equation: TC Pred The predicted thermal conductivity is measured in mW / mK, and BC is the branch content of the base oil for thermal management fluids.

2. The thermal management fluid of claim 1, wherein the electrical system is part of an electric vehicle.

3. The thermal management fluid of claim 1, wherein the electrical system comprises an electric motor.

4. The thermal management fluid according to any one of claims 1-3, wherein the electrical system comprises a battery.

5. The thermal management fluid according to any one of claims 1-3, wherein the thermal management fluid is in direct contact with one or more electrified components of the electrical system to remove heat from the one or more electrified components.

6. The thermal management fluid according to any one of claims 1-3, wherein the naphthenic content of the base oil is 25% by weight or less.

7. The thermal management fluid according to any one of claims 1-3, wherein the thermal management fluid has a thickness of 5 mm. 2 A thermal conductivity of 110 mW / mK or greater at a kinematic viscosity of / s.

8. The thermal management fluid according to any one of claims 1-3 further comprises one or more additives selected from the group consisting of antioxidants, corrosion inhibitors, defoamers, anti-wear agents, dispersants, detergents, viscosity modifiers, and any combination thereof.

9. The thermal management fluid according to any one of claims 1-3 further comprises: at least one phenol-based antioxidant present in an amount of 0.25% by weight or greater, and at least one amine-based antioxidant present in an amount of 0.1% by weight or greater.

10. The thermal management fluid according to any one of claims 1-3 further comprises: at least one phenol-based antioxidant present in an amount of 0.5% by weight or greater, and at least one amine-based antioxidant present in an amount of 0.2% by weight or greater.

11. Methods for cooling electrical systems, including: The thermal management fluid of claim 1 is circulated and contacted with one or more components of the electrical system to remove heat from those components.

12. The method of claim 11, wherein the electrical system is part of an electric vehicle.

13. The method of claim 11, wherein one or more components comprise an electric motor.

14. The method according to any one of claims 11-13, wherein one or more components comprise a battery.

15. The method according to any one of claims 11-13, wherein the contact is direct contact with the electrical system to which heat is to be removed.

16. The method according to any one of claims 11-13, wherein the circulation further comprises circulating the thermal management fluid through a heat exchanger after the thermal management fluid has come into contact with one or more components of the electrical system to remove heat from the cooling fluid.

17. The method according to any one of claims 11-13, wherein the thermal management fluid further comprises one or more additives selected from the group consisting of antioxidants, corrosion inhibitors, defoamers, anti-wear agents, dispersants, detergents, viscosity modifiers, and any combination thereof.

18. The method according to any one of claims 11-13, wherein the thermal management fluid further comprises: At least one phenol-based antioxidant present in an amount of 0.25% by weight or greater, and at least one amine-based antioxidant present in an amount of 0.1% by weight or greater.

19. The method according to any one of claims 11-13, wherein the thermal management fluid further comprises: At least one phenol-based antioxidant present in an amount of 0.5% by weight or greater, and at least one amine-based antioxidant present in an amount of 0.2% by weight or greater.

20. The method according to any one of claims 11-13, wherein the base oil has a naphthenic content of 25% by weight or less.

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