Liquid coolant with dissolved gas for electrical systems

Abstract

A liquid coolant for an electrical system and a method for making the same are disclosed. An exemplary liquid coolant for an electrical system may include a base oil and a dissolved gas in an amount sufficient to measurably affect the fluid viscosity of the liquid coolant, the base oil being the major component of the liquid coolant, and the liquid coolant having a kinematic viscosity of about 7 cSt or less at 100°C.

Description

[Technical Field]

[0001] This disclosure relates to a liquid coolant for electrical systems and a method for producing the same. Such a liquid coolant may contain dissolved gas to reduce viscosity and improve cooling. [Background technology]

[0002] Heat transfer systems are incorporated into many types of electrical systems to remove generated heat and regulate the long-term operation of the electrical system. Often, various electrical systems include electric motors, which may require an efficient heat transfer system to remove the heat generated during operation. Cooling of electric motors can be achieved by circulating a specially designed fluid (referred to herein as a liquid coolant). The effectiveness of a liquid coolant may depend on its viscosity, as well as other properties such as thermal conductivity. Using a low-viscosity coolant can improve the energy efficiency and cooling effect of the fluid pump. However, very low-viscosity coolants can be problematic. For example, a liquid coolant designed with very low viscosity may be highly volatile and flammable, as well as pose a risk of inhalation. A coolant with a kinematic viscosity of less than 4 centistokes (cSt) at 100°C and less than 18 cSt at 40°C, as measured according to ASTM D445, can be considered to have very low viscosity.

[0003] There is a need for a liquid coolant that effectively improves fuel efficiency while also providing the desired levels of volatility and flammability. [Overview of the project]

[0004] This specification discloses exemplary liquid coolants for electrical systems, comprising a base oil and a sufficient amount of dissolved gas to have a measurable effect on the fluid viscosity of the liquid coolant, wherein the base oil is the main component of the liquid coolant and the liquid coolant has a kinematic viscosity of about 7 cSt or less at 100°C.

[0005] This specification further discloses an exemplary method for producing a liquid coolant, comprising introducing a base oil into a container and pressurizing the container with gas so that a certain amount of gas dissolves in the base oil to provide a liquid coolant, wherein the liquid coolant has a kinematic viscosity of about 7 cSt or less at 100°C.

[0006] This specification further discloses exemplary methods for cooling an electrical system, comprising circulating a liquid coolant in contact with one or more components (or constituents) of the electrical system, wherein the liquid coolant comprises a base oil and a dissolved gas, the base oil being the main component of the liquid coolant, the dissolved gas being present in the liquid coolant in an amount sufficient to have a measurable effect on the fluid viscosity of the liquid coolant, and the liquid coolant having a kinematic viscosity of about 7 cSt or less at 100°C. [Brief explanation of the drawing]

[0007] The drawings illustrate specific aspects of the present disclosure and should not be used to limit or define the present disclosure.

[0008] [Figure 1] Figure 1 is a schematic diagram of an exemplary system for introducing dissolved gas into a base oil. [Modes for carrying out the invention]

[0009] The following is a detailed description of the disclosure provided to assist those skilled in the art in implementing the disclosure. Those skilled in the art can modify and change the embodiments described herein without departing from the spirit or scope of the disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the disclosure belongs. The terms used in the description of the disclosure herein are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. All publications, patent applications, patents, drawings, and other references referred herein are expressly incorporated in their entirety by reference.

[0010] The terms “electrical system,” “electrical device,” “electrical system,” “electrical device,” and any variations thereof refer to any system, device, or apparatus that is primarily powered or operated by electrical means and requires a heat transfer system to remove heat generated for prolonged operation. Examples of electrical systems include, but are not limited to, electric vehicles (or automobiles), power electronics contained in electric vehicles (e.g., “on-board” electronics), electric motors, batteries, rechargeable (or rechargeable) battery systems, charging stations, electronics, computers, server banks (or farms), data centers, or any combination thereof.

[0011] The term "electric vehicle" and its variations refer to all-electric and fully electric vehicles, hybrid and hybrid-electric vehicles, which may have, alone or in combination, any of the various parallel or series drivetrain configurations, and include mechanical and electrical systems, subsystems, and components with gears used in the vehicle. These mechanical and electrical systems, subsystems, and components with gears may include, for example, electric vehicle powertrains, powertrain components (or components), drivetrain components, kinetic energy recovery systems (KERS), energy regeneration systems, etc. The terms electric vehicle and hybrid vehicle may be used interchangeably. Furthermore, the term "electric vehicle" is not limited to land vehicles (e.g., automobiles) but is intended to include any type of vehicle that is fully or partially powered, including aircraft (e.g., airplanes, drones, spacecraft, etc.) and marine vehicles (e.g., any type of watercraft, hovercraft, etc.). "Electric vehicle" may refer to manual or automatic vehicles, or hybrids thereof.

[0012] This disclosure relates to liquid coolants for electrical systems and methods for producing the same. According to this embodiment, the liquid coolant may comprise a base oil and a dissolved gas. Exemplary embodiments of the liquid coolant may also comprise additional additives, such as antioxidants. In this disclosure, the term liquid coolant encompasses lubricating oil, lubricating fluid, lubricant, working fluid, cooling fluid, and coolant. Such terms may be used interchangeably.

[0013] The inclusion of dissolved gases in the base oil reduces the viscosity of the resulting liquid coolant. This reduction in viscosity improves the cooling capacity of the liquid coolant. Furthermore, unlike viscosity reduction by other means, the introduction of dissolved gases into the base oil should not cause an increase in volatility or flammability. Since the viscosity reduction is achieved by the inclusion of dissolved gases and not by a change in the molecular structure of the base oil, it should not affect the volatility and flammability of the liquid coolant.

[0014] The viscosity of the liquid coolant can be adjusted by selecting the amount and type of base oil and dissolved gas. In some embodiments, the liquid coolant may have a relatively low kinematic viscosity ("KV100") ("KV40") at 100°C and 40°C. As used herein, the terms "kinematic viscosity at 100°C" or "KV100" of the liquid coolant refer to the kinematic viscosity at 100°C as measured according to ASTM D445. In some embodiments, the liquid coolant may have a KV100 of about 7 centistokes (cSt) or less, or about 6 cSt or less, or about 5 cSt or less, or about 4 cSt or less, or about 3 cSt or less, or about 1 cSt or less. In some embodiments, the liquid coolant may have a KV100 of about 1 cSt to about 5 cSt, or about 2 cSt to about 5 cSt, or about 2 cSt to about 4 cSt. In some embodiments, the liquid coolant may also have a minimum KV100. For example, the liquid coolant may have a KV100 of approximately 0.5 or more, approximately 0.6 or more, approximately 0.7 or more, approximately 0.8 or more, approximately 0.9 or more, or approximately 1.0 or more. In some embodiments, the liquid coolant may be KV100 in the range of about 0.5 cSt to about 7 cSt, or about 0.5 cSt to about 6 cSt, or about 0.5 cSt to about 5 cSt, or about 1 cSt to about 7 cSt, or about 1 cSt to about 6 cSt, or about 1 cSt to about 5 cSt.

[0015] As used herein, the terms “kinematic viscosity at 4°C” or “KV40” of a liquid coolant refer to the kinematic viscosity at 100°C as measured according to ASTM D445. In some embodiments, a liquid coolant may have a KV40 of about 30 centistokes (cSt) or less, or about 28 cSt or less, or about 26 cSt or less, or about 24 cSt or less. In some embodiments, a liquid coolant may have a KV40 of about 15 cSt to about 30 cSt, or about 20 cSt to about 30 cSt, or about 20 cSt to about 28 cSt. In some embodiments, a liquid coolant may be considered to have “very low viscosity” in that embodiments of the liquid coolant may have a KV100 of about 4 cSt or less and a KV40 of about 28 cSt or less.

[0016] A liquid coolant having dissolved gas can have desirable volatility. One measure of volatility can be the flash point. As used herein, the flash point is determined in accordance with ASTM D92 open cup flash point. In some embodiments, the liquid coolant can have a flash point of about 90°C to about 275°C, or a flash point of about 150°C to about 250°C.

[0017] The cooling power of the liquid coolant can be improved by a reduction in viscosity from the dissolved gas. Cooling power depends on various factors and can be quantified by various different tests. One example is the heat transfer coefficient, which is equal to the heat flux divided by the temperature difference, as shown by the following equation. TIFF0007843247000001.tif8150(1) h is the heat transfer coefficient, q is the heat flux, and ΔT is the temperature difference between the surrounding fluid and the solid surface. The heat transfer coefficient can be used to calculate heat transfer between a fluid and a solid. There are various formulations for calculating the heat transfer coefficient for various heat transfer modes. The Dittus - Bolter correlation can be used for many applications and is provided below: TIFF0007843247000002.tif11150(2) h is the heat transfer coefficient, d is the hydraulic diameter, k is the thermal conductivity of the bulk fluid, j is the mass flux, μ is the fluid viscosity, c p is the isobaric heat capacity of the fluid, and n is 0.33 for applications where the liquid coolant is cooler than the wall.

[0018] The density of the liquid coolant is a fluid property for providing sufficient heat transfer performance to an electrical system. The density used herein is determined in accordance with ASTM D4052. In some embodiments, at a temperature of 40 °C, the liquid coolant 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 liquid coolant 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.

[0019] The specific heat of the liquid coolant is another fluid property for providing sufficient heat transfer performance to an electrical system. The specific heat used herein is determined in accordance with ASTM E1269. In some embodiments, at a temperature of 40 °C, the liquid coolant 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 liquid coolant 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, 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.

[0020] The kinematic viscosity of a liquid coolant is another fluid property that provides sufficient heat transfer performance to an electrical system. The kinematic viscosity used herein is determined according to ASTM E1269. In some embodiments, when the average fluid temperature is 40°C, the liquid coolant may have a kinematic 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 liquid coolant may have a kinematic 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.

[0021] The liquid coolants referred to herein offer liquid coolant properties that persist throughout the lifespan of the liquid coolant, as well as compatibility with the electrical systems referred to herein, such as electric vehicles and their components and materials. Exemplary electrical systems and electric vehicle components that can be cooled according to this disclosure include, for example, batteries, electric motors, generators, AC-DC / DC-AC / AC-AC / DC-DC converters, AC-DC / DC-AC / AC-AC / DC-DC transformers, power management systems, electronics that control batteries, on-board chargers, on-board power electronics, ultrafast charging systems, fast charging equipment for charging stations, and stationary ultrafast chargers.

[0022] Depending on the specific electrical system (e.g., electric vehicle batteries, electric motors, generators, AC-DC / DC-AC / AC-AC / DC-DC converters, AC-DC / DC-AC / AC-AC / DC-DC transformers, power management systems, electronics that control batteries, on-board chargers, on-board power electronics, ultrafast charging systems, fast charging equipment at charging stations, stationary ultrafast chargers, etc.), the electrical system may operate over a wide temperature range. For example, an electrical system can operate at a temperature range of approximately -40°C to 175°C, or approximately -25°C to 170°C, or approximately -10°C to 165°C, or approximately 0°C to 160°C, or approximately 10°C to 155°C, or approximately 25°C to 150°C, or approximately 25°C to 125°C, or approximately 30°C to 120°C, or approximately 35°C to 115°C, or approximately 35°C to 105°C, or approximately 35°C to 95°C, or approximately 35°C to 85°C.

[0023] In one embodiment, a single liquid coolant can be used in the electrical system. In another embodiment, multiple liquid coolants can be used in the electrical system; for example, one liquid coolant can be used for the battery and another for other components of the electrical system.

[0024] Liquid coolants referred to herein include, for example, metals, metal alloys, nonmetals, nonmetal alloys, mixed carbon metal composites and alloys, mixed carbon nonmetal composites and alloys, ferrous metals, iron composites and alloys, nonferrous metals, nonferrous composites and alloys, titanium, titanium composites and alloys, aluminum, aluminum composites and alloys, magnesium, magnesium composites and alloys, ion-implanted metals and alloys, and surfaces of equipment components; plasma-modified surfaces; surface modification materials and coatings; single-layer, multi-layer, and gradient layer coatings; polished surfaces; buffed surfaces; etched surfaces; textured surfaces; micro and nanostructures of textured surfaces; superfinished surfaces; diamond Cooling of material compositions and composites including: DLC (diamond-like carbon), high hydrogen content DLC, medium hydrogen content DLC, low hydrogen content DLC, near-zero hydrogen content DLC, 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; and material compositions and composites containing, for example, graphite, carbon, molybdenum, molybdenum disulfide, polytetrafluoroethylene, polyperfluoropropylene, polyperfluoroalkyl ethers, etc.

[0025] As described above, liquid coolants can be used for cooling electrical systems according to this embodiment. The liquid coolants disclosed herein may provide liquid coolant properties that persist throughout the lifespan of the liquid coolant, as well as compatibility with electrical systems referred to herein, such as electric motors, electric vehicles and their corresponding components and materials. Exemplary components of electrical systems that can be cooled according to this disclosure include, for example, electric batteries, electric motors, generators, AC-DC / DC-AC / AC-AC / DC-DC converters, AC-DC / DC-AC / AC-AC / DC-DC transformers, power management systems, electronics that control batteries, on-board chargers, on-board power electronics, ultrafast charging systems, fast charging equipment for charging stations, and stationary ultrafast chargers.

[0026] Depending on the specific electrical system (e.g., electric batteries, electric motors, generators, AC-DC / DC-AC / AC-AC / DC-DC converters, AC-DC / DC-AC / AC-AC / DC-DC transformers, power management systems, electronics that control batteries, on-board chargers, on-board power electronics, ultrafast charging systems, fast charging equipment at charging stations, stationary ultrafast chargers, etc.), the electrical system may operate over a wide temperature range. For example, an electrical system can operate at a temperature range of approximately -40°C to 175°C, or approximately -25°C to 170°C, or approximately -10°C to 165°C, or approximately 0°C to 160°C, or approximately 10°C to 155°C, or approximately 25°C to 150°C, or approximately 25°C to 125°C, or approximately 30°C to 120°C, or approximately 35°C to 115°C, or approximately 35°C to 105°C, or approximately 35°C to 95°C, or approximately 35°C to 85°C.

[0027] In one embodiment, a single liquid coolant can be used in the electrical system. In another embodiment, multiple liquid coolants can be used in the electrical system; for example, one liquid coolant can be used for the battery and another for other components of the electrical system.

[0028] Liquid coolants referred to herein include, for example, metals, metal alloys, nonmetals, nonmetal alloys, mixed carbon metal composites and alloys, mixed carbon nonmetal composites and alloys, ferrous metals, iron composites and alloys, nonferrous metals, nonferrous composites and alloys, titanium, titanium composites and alloys, aluminum, aluminum composites and alloys, magnesium, magnesium composites and alloys, ion-implanted metals and alloys, and surfaces of equipment components; plasma-modified surfaces; surface modification materials and coatings; single-layer, multi-layer, and gradient layer coatings; polished surfaces; buffed surfaces; etched surfaces; textured surfaces; micro and nanostructures of textured surfaces; superfinished surfaces; diamond DLC (Diamond-Like Carbon), DLC with high hydrogen content, DLC with moderate 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 that may be used, for example, containing graphite, carbon, molybdenum, molybdenum disulfide, polytetrafluoroethylene, polyperfluoropropylene, polyperfluoroalkyl ethers, etc.

[0029] In some embodiments, the electrical system may include an oil cooling system. An example of an oil cooling system may include one or more conduits and a pump configured to circulate a liquid coolant through one or more conduits. The pump may include, for example, a positive displacement pump or a centrifugal pump. The liquid coolant may include any of the liquid coolants disclosed herein and may be used to cool components of the electrical system (e.g., electric motors, electric batteries) that form part of the electrical system. In some embodiments, the liquid coolant may be configured to directly cool one or more surfaces of the components of the electrical system, thereby removing heat from the components of the electrical system. After heat exchange with the components of the electrical system, the heated liquid coolant is carried out of the electrical system components 108 at a high temperature. The heated liquid coolant is then transported in the conduits to a heat exchanger included in the oil cooling system. The heat exchanger may function similarly to a radiator by removing heat from the heated liquid coolant. In some embodiments, the heat exchanger may dissipate heat, for example, into another fluid or into air at ambient temperature. The heat exchanger may be a specific device, or it may simply be a system in which heat is lost to the atmosphere as a heat transfer fluid flows through a conduit. The liquid coolant can then be recycled to the components of the electrical system. These descriptions of electrical cooling systems are merely examples, and the liquid coolant can be used with any suitable electrical cooling system for cooling the components of an electrical system.

[0030] One or more embodiments of an oil cooling system may include circulating a liquid coolant in contact with one or more components of an electrical system, such as an electric battery or an electric motor. The liquid coolant can cool the components of the electrical system by absorbing heat from them and thereby removing heat. A suitable oil cooling system may include surface cooling and / or internal cooling of an electric motor. One or more embodiments of an oil cooling system using surface cooling may circulate the liquid coolant through a cooling jacket on the outside of the motor stator. One or more embodiments of an oil cooling system using internal cooling may circulate the liquid coolant through components of the electrical system. By circulating through components of an electrical system, such as an electric motor, the liquid coolant may, in addition to cooling, also lubricate the components of the electrical system (e.g., motor bearings). In some embodiments, surface and internal cooling techniques can be combined. However, these descriptions of cooling techniques are merely examples, and it should be understood that liquid coolants can be used according to other techniques for cooling electric motors.

[0031] base oil An exemplary embodiment of a liquid coolant may comprise one or more base oils. Suitable base oils may include natural oils, mineral oils, and synthetic oils, and fresh oils (or mixtures thereof) that have been unrefined, refined, or re-refined may be used (the latter oils are also known as recycled oils or reprocessed oils). Unrefined oils are those obtained directly from natural or synthetic sources and used without further refining. These include shale oils obtained directly from retort operations, petroleum obtained directly from primary distillation, and ester oils obtained directly from esterification processes. Refined oils are similar to the oils described for unrefined oils, except that the refined oil is subjected to one or more refining steps to improve the base oil properties of at least one liquid coolant. Those skilled in the art are familiar with many refining processes. These processes include solvent extraction, secondary distillation, acid extraction, base extraction, filtration, and percolation (or permeation, leaching, or filtration). Re-refined oils are obtained by a process similar to that of refined oils, but using oils that have already been used as raw materials.

[0032] Groups I, II, III, IV, and V are categories of base oil materials (or base oil stocks) developed and defined by the American Petroleum Institute (API Literature 1509) to create guidelines for liquid coolant base oils. Group I base materials (or base stocks) have a viscosity index of approximately 80–120 and contain more than approximately 0.03% sulfur and / or less than approximately 90% saturated matter. Group II base materials have a viscosity index of approximately 80–120 and contain less than approximately 0.03% sulfur and more than approximately 90% saturated matter. Group III raw materials (or stocks) have a viscosity index greater than approximately 120 and contain less than approximately 0.03% sulfur and more than approximately 90% saturated matter. Group IV includes polyalphaolefins (PAOs). Group V base materials include base materials not included in Groups I–IV. The following table summarizes the characteristics of each of these five groups. Table 1 TIFF0007843247000003.tif52139

[0033] Natural oils include animal oils, vegetable oils (e.g., castor oil, lard), and mineral oils. Animal and vegetable oils with good thermal oxidative stability can be used. Mineral oils vary greatly depending on their source of origin, for example, whether they are paraffin, naphthenes, or mixed paraffin-naphthenes. Oils derived from coal or shale are also useful. Natural oils also differ depending on the method used for their production and refining, for example, the range of distillation and whether it is straight-run or cracking, hydrorefining, or solvent extraction.

[0034] Hydrogenated or hydrocracked base materials of Group II and / or Group III, including synthetic oils such as alkyl aromatics and synthetic esters, are also well-known base material oils.

[0035] Synthetic oils include hydrocarbon oils. Hydrocarbon oils include oils such as polymerized and copolymerized olefins (e.g., polybutylene, polypropylene, propylene-isobutylene copolymer, ethylene-olefin copolymer, and ethylene-alphaolefin copolymer). The base material for polyalphaolefin (PAO) oil is commonly used synthetic hydrocarbon oil. Examples include C8, C8. 10 , C 12 , C 14 PAO derived from olefins or mixtures thereof can be used.

[0036] PAO can be manufactured at 100°C with a viscosity of approximately 350 cSt or less. It is a known substance and is generally available on a major commercial scale from suppliers such as ExxonMobil Chemical Company, Chevron Phillips Chemical Company, and BP. The number-average molecular weight of PAO typically varies from approximately 250 to approximately 3000. PAO has alpha-olefins of C8 to approximately C16, such as 1-octene, 1-decene, and 1-dodecene, but is not particularly limited to C2 to approximately C16. 32They are typically composed of relatively low molecular weight hydrogenated polymers or oligomers of alpha-olefins, including alpha-olefins. Suitable examples of polyalpha-olefins are poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures thereof, as well as polyolefins derived from mixed olefins. However, C 14 ~C 18 Dimers of higher olefins in the range can be used to provide an acceptable low-volatility, low-viscosity base material. Depending on the viscosity grade and starting oligomer, PAO may be primarily trimers and tetramers of the starting olefin, with a small amount of higher oligomer having a viscosity range of 1.5 cSt to 12 cSt. PAO fluids for specific applications may include 3.0 cSt, 3.4 cSt, and / or 3.6 cSt, as well as combinations thereof. If necessary, mixtures of PAO fluids having a viscosity range of 1.5 cSt to about 350 cSt or more can be used.

[0037] For example, PAO fluids can be conveniently prepared by polymerizing alpha-olefins in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst, which may contain aluminum trichloride, boron trifluoride, or a complex of boron trifluoride with an alcohol such as water, ethanol, propanol, or butanol, or a carboxylic acid or ester such as ethyl acetate or ethyl propionate.

[0038] Other useful oil-based materials for liquid coolants include wax-isomerized base materials and base oils, including hydrogenated waxy materials (e.g., light oil, slack wax, waxy materials such as residues from fuel hydrocracking units), hydrogenated Fischer-Tropsch wax, gas-to-liquids (GTL) base materials and base oils, and other wax-isomerized hydrogen-isomerized base materials and base oils, or mixtures thereof. Fischer-Tropsch wax, a high-boiling-point residue of Fischer-Tropsch synthesis, is a high-paraffinic hydrocarbon with a very low sulfur content. The hydrogenation treatment used to produce such base materials can use amorphous hydrogen cracking / hydrogen isomerization catalysts, such as one of the special lubricating oil hydrocracking (LHDC) catalysts, or crystalline hydrogen cracking / hydrogen isomerization catalysts, such as zeolite catalysts. For example, one useful catalyst is ZSM-48.

[0039] Gas-to-liquid (GTL) base oils, Fischer-Tropsch wax-derived base oils, and other wax-derived hydrogenated isomerized (wax-isomerized) base oils are advantageously used in this disclosure and may have useful KV100s of about 3 cSt to about 50 cSt, or about 3 cSt to about 30 cSt, or about 3.5 cSt to about 25 cSt, as exemplified by GTL4 having a KV100 of about 4.0 cSt and a viscosity index of about 141. These gas-to-liquid (GTL) base oils, Fischer-Tropsch wax-derived base oils, and other wax-derived hydrogenated isomerized base oils have useful pour points below about -20°C and, under certain conditions, may have useful pour points below about -25°C, including useful pour points of about -30°C to about -40°C. Useful compositions of gas-to-liquid (GTL) base oils, Fischer-Tropsch wax-derived base oils, and wax-derived hydrogenated isomerized base oils are described below.

[0040] A hydrocarbyl aromatic can be used as a base oil or a component of a base oil and can be any hydrocarbyl molecule containing at least about 5% by weight derived from an aromatic moiety such as a benzenoid or naphthenoid moiety, or a derivative thereof. These hydrocarbyl aromatics include alkylbenzenes, alkylnaphthalenes, alkyldiphenyl oxides, alkylnaphthols, alkyldiphenyl sulfides, alkylated bisphenol A, alkylated thiodiphenols, etc. The aromatic can be monoalkylated, dialkylated, polyalkylated, etc. The aromatic can be monofunctionalized or polyfunctionalized. The hydrocarbyl group can also be composed of a mixture of an alkyl group, an alkenyl group, an alkynyl, a cycloalkyl group, a cycloalkenyl group and other related hydrocarbyl groups. The hydrocarbyl group can range from about C6 to about C 60 up to, for example, from about C8 to about C 20 . A mixture of hydrocarbyl groups can also be used and there can be up to about 3 such substituents. The hydrocarbyl group can optionally contain sulfur, oxygen, and / or nitrogen-containing substituents. The aromatic group can also be derived from a natural (petroleum) source, provided that at least about 5% of the molecule is composed of aromatic moieties of the above type. A viscosity of about 3 cSt to about 50 cSt at 100 °C can be used, and a viscosity of about 3.4 cSt to about 20 cSt is often used for the hydrocarbyl aromatic component. In one embodiment, an alkylnaphthalene in which the alkyl group is mainly composed of 1-hexadecene is used. Other alkylates of the aromatic can be advantageously used. For example, naphthalene or methylnaphthalene can be alkylated with olefins such as octene, decene, dodecene, tetradecene or higher, mixtures of similar olefins, etc. Useful concentrations of hydrocarbyl aromatics in the liquid coolant can be, depending on the application, from about 2% to about 25%, or from about 4% to about 20%, or from about 4% to about 15%.

[0041] Alkylated aromatics, such as the hydrocarbyl aromatics of this disclosure, can be produced by the well-known Friedel-Crafts alkylation of aromatic compounds. For example, aromatic compounds such as benzene or naphthalene are alkylated with olefins, alkyl halides, or alcohols in the presence of a Friedel-Crafts catalyst. Many homogeneous or heterogeneous solid catalysts are known to those skilled in the art. The choice of catalyst depends on the reactivity of the starting materials and the quality requirements of the product. For example, strong acids such as AlCl3, BF3, or HF may be used. In some cases, milder catalysts such as FeCl3 or SnCl4 may be used. In newer alkylation techniques, zeolites or solid superacids are used.

[0042] Esters constitute useful base materials. By using esters such as esters of dibasic acids and monoalkanols, and polyol esters of monocarboxylic acids, the solubility and seal compatibility of additives can be ensured. Examples of the former esters include esters of dicarboxylic acids such as phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acid, and alkenylmalonic acid, as well as esters of various alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol, and 2-ethylhexyl alcohol. Specific examples of these types of esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, and diicosyl sebacate.

[0043] Particularly useful synthetic esters include one or more polyhydric alcohols such as hindered polyols (neopentyl polyols, e.g., neopentyl glycol, trimethylolethane, 2-methyl-2-propyl-1,3-propanediol, trimethylolpropane, pentaerythritol, and dipentaerythritol) and saturated linear fatty acids such as C5-C2 alkanoic acids containing at least about four carbon atoms, e.g., caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. 30 It is an ester obtained by reacting it with an acid, or a corresponding branched-chain fatty acid or an unsaturated fatty acid such as oleic acid, or a mixture of any of these materials.

[0044] Suitable synthetic ester components include esters of trimethylolpropane, trimethylolbutane, trimethylolethane, pentaerythritol and / or dipentaerythritol with one or more monocarboxylic acids containing about 5 to about 10 carbon atoms. These esters are widely available commercially, for example, Mobil P-41 and P-51 esters from ExxonMobil Chemical Company.

[0045] Esters derived from renewable materials such as coconut, palm, rapeseed, soybean, and sunflower are also useful. These esters may be monoesters, diesters, polyol esters, compound esters, or mixtures thereof. These esters are widely available commercially, for example, Mobil P-51 ester from ExxonMobil Chemical Company.

[0046] Formulations (or formations or compositions; formulations) of liquid coolants containing renewable esters are included in this disclosure. In such formulations, the renewable ester content is typically greater than about 70% by weight, or greater than about 80% by weight, or greater than about 90% by weight.

[0047] Other useful fluids include non-conventional or novel (unconventional) base materials that have been treated or synthesized, for example, with catalysts, to provide high-performance heat transfer properties.

[0048] Non-conventional or novel base materials / base oils include mixtures of base materials derived from one or more gas-to-liquid (GTL) materials, isomerized / isodewaxate base stock(s) derived from natural waxes or waxy raw materials, mineral and / or non-mineral oil waxy feedstocks such as slack wax and natural waxes, and non-petroleum-derived waxy materials such as waxy raw materials such as diesel fuel, residues from wax fuel hydrocracking units, wax raffinates, hydrocracking products, pyrocracking products, or waxy substances obtained from other minerals, mineral oils, or coal liquefaction or shale oil, and one or more mixtures of such base materials.

[0049] GTL materials are materials derived from elements as raw materials (or feedstocks), such as gaseous carbon-containing compounds, hydrogen-containing compounds, and / or elements as raw materials (or feedstocks), through one or more synthesis, bonding, deformation, rearrangement, and / or decomposition / deconstruction (or decomposition or dismantling) processes. The base material and / or base oil of a GTL is generally a GTL material derived from hydrocarbons, such as simpler gaseous carbon-containing compounds, hydrogen-containing compounds, and / or waxy synthetic hydrocarbons themselves derived from elements as raw materials. GTL base materials and / or base oils include (1) oils boiling in the lubricating oil boiling point range which are separated / fractionated from synthetic GTL materials, for example by distillation, and subsequently subjected to a final wax treatment step including either or both catalytic dewaxing and / or solvent dewaxing processes to produce lubricating oils with reduced / low pour points; (2) synthetic wax isomers, for example, including hydrodewaxing or hydroisomerizing catalysts and / or solvent dewaxed synthetic waxes or waxy hydrocarbons; (3) hydrodewaxing or hydroisomerizing catalysts and / or solvent dewaxed Fischer-Tropsch (FT) materials (i.e., hydrocarbons, waxy hydrocarbons, waxes, and possible similar oxygen-containing compounds), for example, FT waxy hydrocarbons that are hydrodewaxed or hydroisomerized / followed by catalyst and / or solvent dewaxing, or FT waxes that are hydrodewaxed or hydroisomerized / followed by catalyst (or solvent) dewaxing, or mixtures thereof.

[0050] GTL base materials and / or base oils derived from GTL materials, in particular, hydrogenated or hydrogen isomerized and / or subsequently catalyst and / or solvent dewaxed waxes or waxy raw materials, such as base materials and / or base oils derived from FT materials, are typically characterized by having a KVI00 of about 2 cSt to about 50 cSt. They are further typically characterized by having a pour point (in ASTM D97) of -5°C to about -40°C or lower. They are also typically characterized by having a viscosity index (in ASTM D2270) of about 80 to about 140 or higher.

[0051] Furthermore, GTL base materials and / or base oils typically have high paraffinity (>90% saturation) and may contain mixtures of monocycloparaffins and multicycloparaffins in combination with acyclic isoparaffins. The ratio of naphthenic (i.e., cycloparaffin) content in such combinations varies depending on the catalyst and temperature used. In addition, GTL base materials and / or base oils typically have very low sulfur and nitrogen content, generally containing less than about 10 ppm, and more typically less than about 5 ppm, of each of these elements. The sulfur and nitrogen content of GTL base materials and / or base oils obtained from FT materials, especially FT waxes, is essentially zero. Furthermore, because they do not contain phosphorus and aromatic compounds, they are particularly suitable materially for forming low SAP products.

[0052] The terms GTL base material and / or base oil, and / or wax isomerized base material and / or base oil, should be understood to encompass individual fractions (or fractions or distillates; fraction) of a wide viscosity range of material, such as those recovered in the manufacturing process, mixtures of two or more such fractions, and mixtures (or blends; blend) of one or more low viscosity fractions and one or more high viscosity fractions to produce a blend that exhibits a target kinematic viscosity.

[0053] The GTL-based materials and / or the GTL materials from which the base oil is derived can be Fischer-Tropsch materials (i.e., hydrocarbons, waxy hydrocarbons, waxes).

[0054] As noted above, Group V base materials may include base materials not included in Groups I-IV. Examples of suitable Group V base materials include, but are not limited to, alkylated aromatics such as hydrocarbyl aromatics and alkylnaphthalenes; esters including mono- and polyesters; silicate esters; polyalkylene glycols including oil-soluble polyalkylene glycols; polytetrahydrofuran; and ionic liquids.

[0055] The base oil for use in the formulated liquid coolants useful in the present disclosure is any of API Group I, Group II, Group III, Group IV, Group V oils, and mixtures thereof, or API Group II, Group III, Group IV, Group V oils, and mixtures thereof, or Group III, Group IV, Group V base oils, and mixtures thereof corresponding to various oils. High paraffin base oils can be advantageously used in the formulated liquid coolants useful in the present disclosure. Small amounts of Group I materials (or stocks) can also be used, such as amounts used to dilute additives for blending into formulated lubricating oil products. With respect to Group II materials, the Group II materials can be Group II having a higher quality range associated with that material, i.e., a viscosity index in the range of 100 < VI < 120.

[0056] Examples of base fluids suitable for use in the formulated liquid coolants useful in the present disclosure include, for example, aromatic hydrocarbons, polyolefins, paraffins, isoparaffins, esters, ethers, fluorinated fluids, nanofluids, and silicone oils.

[0057] The base oil may typically constitute the main component of the liquid coolant of this disclosure and may be present in an amount ranging from about 50% to about 99% by weight, for example, about 70% to about 90% by weight or about 85% to about 95% by weight, on a total weight basis of the liquid coolant. The base oil may be selected from either synthetic or natural oils, which are typically used as crankcase lubricants for spark-ignition and compression-ignition engines. The base oil may have a KV100 of 2.5 cSt to 12 cSt, or 2.5 cSt to 9 cSt. Mixtures of synthetic and natural base oils may be used as needed. Bimodal mixtures of base materials of groups I, II, III, IV, and / or V may also be used as needed.

[0058] Dissolved gas Exemplary embodiments of liquid coolants may include dissolved gases. As mentioned above, including dissolved gases can reduce the viscosity of the liquid coolant, resulting in improved cooling. However, even if there is a viscosity reduction in the liquid coolant due to the dissolved gases, there should not be an undesirable increase in volatility and / or flammability, which is typically associated with viscosity reduction.

[0059] The dissolved gas may include any of the various gases soluble in the base oil. Suitable gases may include, but are not limited to, inert gases such as carbon dioxide and nitrogen, and noble gases such as argon, helium, neon, krypton, and xenon. Helium and neon can be used because they are non-reactive, but they may be difficult to dissolve in the base oil, and therefore have a potentially less impact on viscosity compared to other inert gases such as carbon dioxide, argon, and krypton. Additional gases are also suitable. For example, suitable additional gases may include, but are not limited to, air, oxygen, hydrogen, nitrogen, ammonia, carbon monoxide, and hydrocarbons such as methane, ethane, ethylene, acetylene, propane, propylene, and butane. Additional non-reactive gases such as air and nitrogen can be used as liquid coolants, but their effect on dissolving in the base oil may be less than that of some of the inert gases. More reactive additional gases such as oxygen, hydrogen, ammonia, and carbon monoxide can also be used, but they have only a moderate effect on dissolving the base oil. Flammable hydrocarbons such as methane, ethane, ethylene, propylene, and acetylene can be used and are very effective in reducing viscosity, but precautions must be taken because the flammability of these hydrocarbons can cause safety problems.

[0060] The concentration of gas dissolved in a liquid coolant is a function of other factors such as the solubility of the gas in the base oil, pressure, and temperature. For example, temperature is a factor that affects gas solubility; as the temperature increases, the solubility of the gas decreases. Furthermore, pressure is another factor that affects gas solubility; as the pressure of the gas increases, the solubility of the gas increases. The gas may be present in the liquid coolant in an amount sufficient to have a measurable effect on the fluid viscosity. As used herein, a measurable effect on viscosity refers to a decrease in viscosity of at least 2% compared to the repeatability of standard viscosity measurements (ASTM D445) of about 1%. The exact decrease in viscosity is due to many factors. For example, 0.6 g / L (g / L) of argon dissolved in a PAO base oil with a KV of about 2 cSt and a KV of 100 has been shown to decrease the viscosity by at least 2%, and 0.2 g / L of argon dissolved in a PAO base oil with a KV of about 4 cSt and a KV of 100 has been shown to decrease the viscosity by at least 2%. It has also been shown that carbon dioxide has a strong effect on viscosity. Therefore, some embodiments may include dissolved gas in the liquid coolant in amounts of about 0.2 g / L or more. For example, the dissolved gas may be present in amounts of about 0.25 g / L or more, about 0.3 g / L or more, about 0.35 g / L or more, about 0.4 g / L or more, about 0.45 g / L or more, or about 0.5 g / L or more. The maximum amount of dissolved gas in the liquid coolant is not limited but can vary based on many factors, including the specific gas and base oil, as well as temperature and pressure. For example, the dissolved gas may be present in amounts of about 380 g / L or less, which is approximately equal to the concentration of carbon dioxide in a PAO base oil having a KV100 of about 4 cSt when exposed to a carbon dioxide atmosphere at 15,000 psi (103,000 kPa) and 20°C. As a further example, the dissolved gas may be present in an amount of approximately 19.5 or less, which is approximately equal to the concentration of carbon dioxide in the PAO when exposed to a carbon dioxide atmosphere at 1160 psi (8000 kPa) and 60°C. In some embodiments, the amount of dissolved gas in the liquid coolant may range from approximately 0.2 g / L to approximately 400 g / L.For example, the amount of dissolved gas is approximately 0.2g / L to 200g / L, approximately 0.2g / L to 100g / L, approximately 0.2g / L to 40g / L, approximately 0.2g / L to 20g / L, approximately 0.2g / L to 10g / L, approximately 0.2g / L to 5g / L, approximately 0.2g / L to 1g / L, approximately 0.3g / L to 400g / L, 0.3g / L to 200g / L, approximately 0.3g / L to 100g / L, approximately 0.3g / L to 40g / L, and approximately 0.3 g / L ~ approx. 20g / L, approx. 0.3g / L ~ approx. 10g / L, approx. 0.3g / L ~ approx. 5g / L, approx. 0.3g / L ~ approx. 1g / L, 0.4g / L ~ approx. 400g / L, 0.4g / L ~ approx. 200g / L, approx. 0.4g / L ~ It can range from about 100 g / L, about 0.4 g / L to about 40 g / L, about 0.4 g / L to about 20 g / L, about 0.4 g / L to about 10 g / L, about 0.4 g / L to about 5 g / L, or about 0.4 g / L to about 1 g / L.

[0061] According to this embodiment, the concentration of dissolved gas in the liquid coolant may exceed the equilibrium volume of gas in the liquid coolant at standard ambient temperature and pressure in an air atmosphere. As used herein, standard ambient temperature and pressure (SATP) refers to 25°C and 100kPa. In some embodiments, the concentration of dissolved gas in the liquid coolant may exceed the equilibrium volume at SATP in an air atmosphere by about 10%, about 20%, about 30%, about 50%, about 100%, about 200%, or about 500% or more.

[0062] Any suitable technique can be used to dissolve the gas in the base oil of the liquid coolant. Gas dissolution may involve placing the liquid coolant containing the base oil in a gas atmosphere. The volume of gas dissolved in the liquid coolant can be controlled by selecting the gas volume, gas pressure, and temperature of the liquid coolant. The viscosity of the liquid coolant depends on the concentration of the dissolved gas and can therefore be monitored to determine the volume of dissolved gas. Increasing the pressure increases dissolution and decreases viscosity. After dissolution, the liquid coolant can be stored in a pressurized container for a certain period, for example, about one day or more, or about two days or more, or about one week or more.

[0063] Figure 1 shows an example of a gas dissolution system 10. As shown, the gas dissolution system 10 may include a container 12, a liquid coolant 14, and a gas source 16. Gas from the gas source 16 is supplied to the container 12 and dissolves in the liquid coolant 14, thereby reducing the viscosity of the liquid coolant and improving its cooling capacity.

[0064] In the illustrated embodiment, the liquid coolant 14 is placed inside the container 12. The liquid coolant 14 may contain any of the aforementioned base oils suitable for use in a liquid coolant. A gas source 16 may be used to supply gas to the container 12 so that the container 12 has a gas atmosphere 18. The container 12 is said to have a gas atmosphere 18 because the gas from the gas source 16 surrounds the liquid coolant 14 inside the container 12. The gas atmosphere 18 may contain about 90% or more by volume of gas, about 95% or more by volume of gas, about 96% or more by volume of gas, about 97% or more by volume of gas, about 98% or more by volume of gas, about 99% or more by volume of gas, or about 99.9% or more by volume of gas. The gas may be any of the aforementioned gases for dissolving in the base oil of the liquid coolant 14. The gas source 16 may include, for example, a pressure vessel (or vessel) or other suitable container for storing gas above atmospheric pressure.

[0065] The gas dissolution system 10 may further include a pressure regulator 20. The pressure regulator 20 may be located, for example, in a flow path 22 between the gas source 16 and the container 12. The pressure regulator 20 may be used to control the gas pressure in the container 12. Although not shown separately, the pressure regulator 20 may include, for example, a pressure sensor, a controller, and / or a flow valve.

[0066] The gas dissolution system 10 may further include a viscometer 24. The viscometer 24 may be used to measure the viscosity of the liquid coolant 14. In some embodiments, the viscosity of the liquid coolant 14 can be monitored by the viscometer 14. As previously mentioned, the gas in the gas atmosphere 18 needs to dissolve in the liquid coolant 14. The pressure of the gas atmosphere 18 and the temperature of the liquid coolant 14 may be controlled to control the dissolution of the gas and thereby control the viscosity of the liquid coolant 14.

[0067] The gas dissolution system 10 may further include a temperature controller 26 for monitoring the temperature of the liquid coolant 14. The temperature controller 26 may receive temperature measurements of the liquid coolant 14 from a temperature sensor 28, such as a thermocouple. A set temperature value may be input to and / or stored in the temperature controller 26. The temperature controller 26 may compare the temperature measurements to the set temperature value to determine how much heating and / or cooling is required. In response to this comparison, the temperature controller 26 may generate an output signal to a thermal control device 30. As shown in the figure, the thermal control device 30 may come into contact with the liquid coolant 14. Based on the output signal, the thermal control device 30 may heat and / or cool the liquid coolant 14. The thermal control device 30 may include a heater, a cooler, or a combination thereof.

[0068] During operation, the gas dissolution system 10 may be used to dissolve gas in the liquid coolant 14. The liquid coolant 14, containing a base oil, may be introduced into the container 12. Gas from the gas source 16 may be used to provide a gas atmosphere 18 within the container 12. Within the container, the gas from the gas atmosphere 18 needs to dissolve in the liquid coolant 14. The pressure of the gas atmosphere within the container 12 may be controlled. For example, a pressure regulator 20 or other suitable device may be used to control the pressure of the gas atmosphere 18. For example, a set pressure value may be input to the pressure regulator 20 or otherwise stored. The pressure regulator 20 may be used to control the flow of gas into the container 12 to provide the set pressure value of the gas atmosphere 18 within the container 12. The temperature of the liquid coolant 14 may be controlled, for example, by a temperature controller 26.

[0069] Additives to liquid coolants Formulated liquid coolants useful in this disclosure may additionally include one or more commonly used performance additives for liquid coolants, including but not limited to antioxidants, corrosion inhibitors, defoamers, anti-wear additives, antistatic additives, pour point depressants, nanomaterials, nanoparticles, dispersants, surfactants, viscosity modifiers, metal passivators, ionic liquids, extreme pressure additives, anti-seize agents, wax modifiers, fluid loss additives, seal compatibility agents, lubricants, friction modifiers, anti-dyeing agents, colorants, anti-emulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, adhesives, and colorants. If a liquid coolant contains one or more of the above additives, the additives are blended into the composition in an amount sufficient to perform their intended function. These additives may be used with various amounts of diluent oil, which may range from 5% to 50% by weight. The additives useful in this disclosure do not need to be soluble in the liquid coolant. The types and amounts of performance additives used in combination with this disclosure in a liquid coolant are not limited by the examples shown herein.

[0070] Accordingly, the foregoing description illustrates a liquid coolant that may contain dissolved gases to reduce viscosity in order to provide improved cooling, and a method for producing the same. The foregoing liquid coolant and the corresponding production method may further include any one or more of the following embodiments:

[0071] Embodiment 1. A liquid coolant for an electrical system, comprising a base oil and a sufficient amount of dissolved gas to have a measurable effect on the fluid viscosity of the liquid coolant, wherein the base oil is the main component of the liquid coolant and the liquid coolant has a kinematic viscosity of about 7 cSt or less at 100°C.

[0072] Embodiment 2. The liquid coolant according to claim 1, wherein the base oil comprises at least one base material selected from the group consisting of base materials of group I, base materials of group II, base materials of group III, base materials of group IV, base materials of group V, and combinations thereof.

[0073] Embodiment 3. The liquid coolant according to claim 1 or claim 2, wherein the base oil comprises a polyalphaolefin-based material.

[0074] Embodiment 4. The liquid coolant according to claim 1 or 2, wherein the base oil comprises at least one Group V base material selected from the group consisting of hydrocarbyl aromatics, alkylated aromatics, monoesters, polyesters, silicate esters, polyalkylene glycols, polytetrahydrofurans, ionic liquids, and combinations thereof.

[0075] Embodiment 5. A liquid coolant according to any one of Embodiments 1 to 4, wherein the dissolved gas contains an amount of inert gas of about 0.2 grams or more per liter of liquid coolant.

[0076] Embodiment 6. A liquid coolant according to any one of Embodiments 1 to 4, wherein the dissolved gas contains an amount of carbon dioxide of about 0.2 grams or more per liter of liquid coolant.

[0077] Embodiment 7. A liquid coolant according to any one of Embodiments 1 to 4, wherein the dissolved gas contains a noble gas in an amount of approximately 0.2 grams or more per liter of liquid coolant.

[0078] Embodiment 8. A liquid coolant according to any one of Embodiments 1 to 4, wherein the dissolved gas contains an amount of argon of about 0.2 grams or more per liter of liquid coolant.

[0079] Embodiment 9. A liquid coolant according to any one of Embodiments 1 to 4, wherein the dissolved gas contains a hydrocarbon in an amount of about 0.2 grams or more per liter of liquid coolant.

[0080] Embodiment 10. A liquid coolant according to any one of embodiments 1 to 9, wherein the dissolved gas is present in an amount of approximately 0.2 grams to approximately 400 grams per liter of liquid coolant.

[0081] Embodiment 11. A liquid coolant according to any one of embodiments 1 to 10, wherein the dissolved gas is present in an amount of approximately 0.5 grams to approximately 200 grams per liter of liquid coolant.

[0082] Embodiment 12. A liquid coolant according to any one of Embodiments 1 to 11, wherein the kinematic viscosity of the liquid coolant at 100°C is about 1 cSt to about 4 cSt, the heat capacity of the liquid coolant is about 2.0 kJ / kgK or more, and the density of the liquid coolant is about 0.92 g / mL or more.

[0083] Embodiment 13. The liquid coolant according to Embodiment 12, wherein the base oil contains a polyalphaolefin-based material and the dissolved gas contains carbon dioxide in an amount of about 0.2 grams or more per liter of liquid coolant.

[0084] Embodiment 14. A method for producing a liquid coolant, comprising introducing a base oil into a container and pressurizing the container with gas so that a certain amount of gas dissolves in the base oil to provide a liquid coolant, wherein the liquid coolant has a kinematic viscosity of about 7 cSt or less at 100°C.

[0085] Embodiment 15. The method according to claim 14, wherein the gas comprises a noble gas dissolved in a liquid coolant in an amount of about 0.2 grams or more per liter.

[0086] Embodiment 16. The method according to claim 14, wherein the gas contains carbon dioxide dissolved in a liquid coolant in an amount of about 0.2 grams or more per liter.

[0087] Embodiment 17. The method according to any one of embodiments 14 to 16, wherein the gas atmosphere inside the container contains gas at a concentration of approximately 90% or more by volume.

[0088] Embodiment 18. The method according to any one of embodiments 14 to 17, further comprising monitoring the viscosity of the base oil in the container with a viscometer.

[0089] Embodiment 19. The method according to Embodiment 18, further comprising adjusting the pressure inside the container according to viscosity.

[0090] Embodiment 20. The method according to any one of embodiments 14 to 19, further comprising monitoring the temperature of the base oil in the container.

[0091] Embodiment 21. The method according to any one of embodiments 14 to 20, further comprising storing a liquid coolant in a sealed container for about one day or more in the atmosphere of the gas in the sealed container, wherein the sealed container is the container or another container.

[0092] Embodiment 22. A method for cooling an electrical system, comprising circulating a liquid coolant in contact with one or more components of the electrical system, wherein the liquid coolant comprises a base oil and a dissolved gas, the base oil being the main component of the liquid coolant, the dissolved gas being present in the liquid coolant in an amount sufficient to have a measurable effect on the fluid viscosity of the liquid coolant, and the liquid coolant having a kinematic viscosity of about 7 cSt or less at 100°C.

[0093] Embodiment 23. The method according to claim 22, wherein the circulation includes circulating the liquid coolant through an electric motor.

[0094] Embodiment 24. The method according to claim 22, wherein the gas contains an amount of carbon dioxide of about 0.2 grams or more per liter of liquid coolant. [Examples]

[0095] To facilitate a better understanding of this disclosure, the following examples of specific aspects of several embodiments are given. The following examples should not be read to limit or define the entire scope of this disclosure.

[0096] Example 1 This example was conducted to illustrate the dissolution of gas into the base oil. The base oil used in this example had a concentration of approximately 0.82 g / cm³ at 15°C. 3 The PAO4 base oil had densities of approximately 4 cSt (KV100) and approximately 18.4 cSt (KV40). The PAO4 base oil has a flash point of approximately 218°C and a pressure of 15.3 MPa. 0.5 It also had liquid solubility parameters. The gas had a gas solubility parameter of 14.81 MPa. 0.5 It was carbon dioxide.

[0097] This example was carried out using a test system for measuring the properties of a sample liquid coolant. The test system not only provided agitation to achieve gas-liquid equilibrium but also allowed for continuous circulation of the liquid coolant. PAO base oil was first filled into the bulk fluid reservoir by gravimetric means and cooled to a temperature approximately 10 Kelvin below room temperature. At this point, gas was filled into the bulk fluid reservoir by gravimetric means from a small stainless steel cell to obtain the desired bulk composition in the test system. Once the system was filled, a gear pump was started to circulate the liquid coolant at each measurement stage. In the bulk fluid reservoir, the bulk mixing pressure was measured using a calibrated pressure transducer. The density of the liquid was measured in the first measurement stage using a mass flow meter. The mass flow meter measured the liquid density, circulating fluid temperature, and circulating fluid mass flow rate. The viscosity of the liquid was measured in the second measurement stage using two high-pressure viscometers with overlapping ranges. The entire flow loop was placed in a temperature chamber to keep the temperature changes of the various components below 3 K.

[0098] Experimental measurements of liquid density, vapor pressure, and viscosity were recorded over a temperature range of -20°C to 150°C. The experiment was repeated over this temperature range at pressures ranging from 0 bar to 100 bar. From these experimental measurements, the viscosity reduction rate and gas content of the liquid coolant were calculated. Viscosity reduction was calculated compared to a control sample without gas dissolution at 0 bar. The results of this test are shown in the table below. Table 2 TIFF0007843247000004.tif187149

[0099] As shown in Table 2 above, the viscosity of the liquid coolant decreased as the concentration of dissolved carbon dioxide increased. For example, the liquid coolant had a viscosity of 4.87 cSt at atmospheric pressure and 100°C with no dissolved carbon dioxide, but its viscosity was 2.45 cSt at 100 bar and 100°C with 12 g / L of dissolved carbon dioxide present, showing a viscosity decrease of 49.7%.

[0100] Example 2 This example was conducted to further demonstrate the dissolution of gas in the base oil. The base oil used in this example had a concentration of approximately 0.82 g / cm³ at 15°C. 3 The PAO4 base oil had densities of approximately 4 cSt for KV100 and approximately 18.4 cSt for KV40. The PAO4 base oil also had a flash point of approximately 218°C and a pressure of 15.3 MPa. 0.5 The liquid solubility parameter was 7.77 MPa. 0.5 It was argon.

[0101] The test system described in Example 1 was used in this example. Experimental measurements of liquid density, vapor pressure, and viscosity were recorded in the temperature range of -20°C to 150°C. The experiment was repeated over this temperature range at pressures ranging from 0 bar to 125 bar. From these experimental measurements, the viscosity reduction rate and gas content of the liquid coolant were calculated. The viscosity reduction was calculated compared to a control sample without gas dissolution at 0 bar. The results of this test are shown in the table below. Table 3 TIFF0007843247000005.tif240144

[0102] As shown in Table 3 above, the viscosity of the liquid coolant decreased as the concentration of dissolved argon increased. For example, the liquid coolant had a viscosity of 5.02 cSt at atmospheric pressure and 100°C without dissolved argon, but a viscosity of 3.35 cSt in the presence of 3.35 g / L of dissolved argon at 100 bar and 100°C, showing a viscosity decrease of 21.9%.

[0103] Example 3 This example was conducted to further illustrate the dissolution of gas into the base oil. The base oil used in this example had a concentration of approximately 0.80 g / cm³ at 15°C. 3 The PAO2 base oil had densities of approximately 1.7 cSt for KV100 and approximately 5.1 cSt for KV40. The PAO2 base oil also had a flash point of approximately 162°C and a pressure of 15.5 MPa. 0.5 The liquid solubility parameter was 7.77 MPa. 0.5 It was argon.

[0104] The test system described in Example 1 was used in this example. Experimental measurements of liquid density, vapor pressure, and viscosity were recorded in the temperature range of -20°C to 150°C. The experiment was repeated over this temperature range at pressures ranging from 0 bar to 125 bar. From these experimental measurements, the viscosity reduction rate and gas content of the liquid coolant were calculated. The viscosity reduction was calculated compared to a control sample without gas dissolution at 0 bar. The results of this test are shown in the table below. Table 4 TIFF0007843247000006.tif240163

[0105] As shown in Table 4 above, the viscosity of the liquid coolant decreased as the concentration of dissolved argon increased. For example, the liquid coolant had a viscosity of 2.39 cSt at atmospheric pressure and 100°C without dissolved argon, but a viscosity of 2.02 cSt in the presence of 3.25 g / L of dissolved argon at 100 bar and 100°C, showing a viscosity decrease of 15.7%.

[0106] Example 4 This example was conducted to further illustrate the dissolution of gas into the base oil. The base oil used in this example had a concentration of approximately 0.86 g / cm³ at 15°C. 3 The base oil was a heavily (or severely) hydrogenated naphthenic base oil having densities of approximately 1.2 cSt (KV100) and approximately 2.8 cSt (KV40). The base oil also had a flash point of approximately 106°C and a pressure of 15.6 MPa. 0.5 The liquid had the following solubility parameters. The gas had a gas solubility parameter of 14.81 MPa. 0.5 It was carbon dioxide.

[0107] The test system described in Example 1 was used in this example. Experimental measurements of liquid density, vapor pressure, and viscosity were recorded in the temperature range of -20°C to 150°C. The experiment was repeated over this temperature range at pressures ranging from 0 bar to 100 bar. From these experimental measurements, the viscosity reduction rate and gas content of the liquid coolant were calculated. The viscosity reduction was calculated compared to a control sample without gas dissolution at 0 bar. The results of this test are shown in the table below. Table 5 TIFF0007843247000007.tif218149

[0108] As shown in Table 5 above, the viscosity of the liquid coolant decreased as the concentration of dissolved carbon dioxide increased. For example, the liquid coolant had a viscosity of 1.9 cSt at atmospheric pressure and 100°C when no carbon dioxide was dissolved, but its viscosity was 1.3 cSt when 17.28 g / L of dissolved carbon dioxide was present at 100 bar and 100°C, showing a viscosity decrease of 32.3%.

[0109] Example 5 This example was conducted to further illustrate the dissolution of gas into the base oil. The base oil used in this example had a concentration of approximately 0.86 g / cm³ at 15°C. 3 The base oil was a heavily (or severely) hydrogenated naphthenic base oil having densities of approximately 1.2 cSt (KV100) and approximately 2.8 cSt (KV40). The base oil also had a flash point of approximately 106°C and a pressure of 15.6 MPa. 0.5 The liquid solubility parameter was 7.77 MPa. 0.5 It was argon.

[0110] The test system described in Example 1 was used in this example. Experimental measurements of liquid density, vapor pressure, and viscosity were recorded in the temperature range of -20°C to 150°C. The experiment was repeated over this temperature range at pressures ranging from 0 bar to 125 bar. From these experimental measurements, the viscosity reduction rate and gas content of the liquid coolant were calculated. The viscosity reduction was calculated compared to a control sample without gas dissolution at 0 bar. The results of this test are shown in the table below. Table 6 TIFF0007843247000008.tif236161

[0111] As shown in Table 6 above, the viscosity of the liquid coolant decreased as the concentration of dissolved argon increased. For example, the liquid coolant had a viscosity of 1.9 cSt at atmospheric pressure and 100°C when no argon was dissolved, but it had a viscosity of 1.72 cSt in the presence of 3.21 g / L of dissolved argon at 100 bar and 100°C, showing a viscosity decrease of 9.8%.

[0112] While this disclosure has been described in terms of many embodiments and examples, those skilled in the art who benefit from this disclosure will understand that other embodiments can be devised that do not depart from the scope and spirit of the invention disclosed herein. Although individual embodiments have been discussed, the invention covers all combinations of all such embodiments.

[0113] Where a range of values ​​is indicated, unless otherwise explicitly indicated in the context (for example, the number of carbon atoms within the range is given for a group containing many carbon atoms), each intervening value is understood to be between the upper and lower limits of that range, up to the tenth of the unit of the lower limit, and any other indicated or intervening values ​​within that range are included in this disclosure. These smaller upper and lower limits may independently be included in smaller ranges and are included in this disclosure, subject to any specifically excluded limits within the indicated range. If a indicated range includes one or both limits, a range excluding both included limits is also included in this disclosure.

[0114] Furthermore, unless explicitly stated otherwise, it should be understood that in any method claimed herein, which involves multiple steps or actions, the order of the steps or actions of the method is not necessarily limited to the order in which the steps or actions are described.

[0115] The following terms are used to describe this disclosure. If a term is not specifically defined herein, it shall be given the meaning that is technically recognized by those skilled in the art in relation to its use in describing this disclosure.

[0116] As used herein and in the appended claims, the articles “a” and “an” are used herein to refer to one or more (i.e., at least one) grammatical objects of the article, unless the context explicitly indicates otherwise. For example, “an element” means one or more elements.

[0117] As used herein and in the claims, the phrase “and / or” should be understood to mean “either or both” of the combined elements, i.e., elements that exist in some cases conjugately and in other cases separately. Multiple elements listed in “and / or” should be interpreted in the same way as “one or more” of the combined elements. Other elements other than those specifically identified by the “and / or” phrase may exist as they may or may not be related to those specifically identified elements. Thus, as an unrestrictive example, a reference to “A and / or B” when used in conjunction with unrestrictive language such as “including” may, in one embodiment, refer to A only (optionally including elements other than B); in another embodiment, refer to B only (optionally including elements other than A); and in yet another embodiment, refer to both A and B (optionally including other elements), and so on.

[0118] As used herein and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” is interpreted as inclusive; that is, it is interpreted as including not just one of many elements or a list of elements, but two or more, optionally, additional items not on the list. Only terms that are explicitly indicated in the opposite way, such as “one of” or “exactly one,” or “consisting of” when used in a claim, refer to including exactly one element of many elements or a list of elements. In general, as used herein, the term “or” is interpreted only as indicating exclusive substitutes (i.e., one or the other, but not both) when defined by exclusive terms such as “either,” “one of,” “only one of” or “exactly one.”

[0119] The terms “about” or “approximately” mean an acceptable experimental error for a particular value as determined by those skilled in the art, which depends in part on how the value is measured or determined. All numerical values ​​in the specification and claims are modified herein by the values ​​indicated as “about” or “approximately” to take into account the experimental errors and variations that would be expected by those skilled in the art.

[0120] In the specification and claims, the terms “major amount” or “major component” with respect to components contained in the liquid coolant mean 50% or more by weight, or 60% or more by weight, or 70% or more by weight, or 80% or more by weight, or 90% or more by weight, based on the total weight of the liquid coolant. In the specification and claims, the terms “trace amount” or “trace component” with respect to components contained in the liquid coolant mean less than 50% by weight, or 40% or less by weight, or 30% or less by weight, or 20% or more by weight, or 10% or less by weight, or 5% or less by weight, or 2% or less by weight, or 1% or less by weight, based on the total weight of the liquid coolant. In the specification and claims, the terms “substantially absent” or “essentially absent” with respect to components contained in the liquid coolant mean that a particular component is present at 0% by weight in the lubricant, or at an impurity type level in the lubricant (less than 100 ppm, or less than 20 ppm, or less than 10 ppm, or less than 1 ppm).

[0121] As with the above specification, in the claims, all transitional phrases such as “comprising,” “including,” “carry,” “have,” “containing,” “involving,” “holding,” and “composed” should be understood as unrestrictive, meaning they include but are not restrictive. Only the transitional phrases “consisting of” and “essentially consisting of” are closed or semi-closed transitional phrases, respectively.

[0122] As used herein and in the claims, the phrase “at least one” should be understood to mean at least one element selected from any one or more elements in a list of elements, but not necessarily at least one of each and all elements specifically listed in the list of elements, nor exclude any combination of elements in the list of elements. By this definition, elements other than those specifically identified in the list of elements to which the phrase “at least one” refers may exist, whether related to or unrelated to the specifically identified elements. Therefore, as a non-restrictive 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”) means, in one embodiment, at least one A, possibly including two or more A's, no B (and possibly including elements other than B); in another embodiment, at least one B, possibly including two or more B's, no A (and possibly including elements other than A); in yet another embodiment, at least one A, possibly including two or more A's, and at least one B, possibly including two or more B's (and possibly including other elements), etc.

Claims

1. A liquid coolant for electrical systems, A single base oil; and A sufficient amount of dissolved gas to have a measurable effect on the fluid viscosity of the liquid coolant. Includes, The base oil is the main component of the liquid coolant and is a polyalphaolefin (PAO) or naphthenic base oil, the dissolved gas is carbon dioxide or argon gas, and the liquid coolant has a kinematic viscosity of 1 cSt to 4 cSt at 100°C. A liquid coolant in which the dissolved gas is present in an amount of 0.5 grams to 20 grams per liter of liquid coolant.

2. A method for cooling an electrical system, comprising circulating a liquid coolant in contact with one or more components of the electrical system, wherein the liquid coolant comprises a single base oil and a dissolved gas, the base oil being the main component of the liquid coolant and being a polyalphaolefin (PAO) or naphthenic base oil, the dissolved gas being carbon dioxide or argon gas, the dissolved gas being present in the liquid coolant in an amount sufficient to have a measurable effect on the fluid viscosity of the liquid coolant, and the liquid coolant having a kinematic viscosity of 1 cSt to 4 cSt at 100°C. A method wherein the dissolved gas is present in an amount of 0.5 grams to 20 grams per liter of liquid coolant.

3. The method according to claim 2, wherein the circulation includes circulating the liquid coolant through an electric motor.

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