Heat exchange method using low GWP fluids

Abstract

The present invention relates to a method for exchanging heat with a body, comprising using a heat transfer fluid, said heat transfer fluid comprising one or more fluorinated nitro compounds of the following general formula (I): [Formula 1] TIFF2025531164000009.tif42170(in the formula: at least two of R1, R2, R3, and R4 are independently selected from H, Cl, and F, provided that at least one is H or Cl; R1, R2, R3, and R4, which are not H, F, or Cl, are selected from partially halogenated alkyl and fully halogenated alkyl, the alkyl chain being C1-C4 and the halogen being selected from Cl and F).

Description

[Technical Field]

[0001] The present invention relates to a method for exchanging heat with a body using a composition comprising selected fluorinated nitro compounds having low GWP as a heat transfer fluid. [Background technology]

[0002] Heat transfer fluids are known in the art for use in heating and cooling systems. Typically, heat transfer fluids include water, saline solutions, alcohols, glycols, ammonia, hydrocarbons, ethers, and various halogenated derivatives of these materials, such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HFCs), and (per)fluorinated polyethers (PFPEs).

[0003] Heat transfer fluids are used to transfer heat from one object to another, typically a heat source to a heat sink, resulting in cooling of the heat source, heating of the heat sink, or removal of unwanted heat generated by the heat source. The heat transfer fluid provides a thermal path between the heat source and the heat sink, and it may be circulated by a loop or other flow system to improve heat flow, or it may be in direct contact with the heat source and heat sink. Simpler systems simply use airflow as the heat transfer fluid, while more complex systems use specially designed gases or liquids that are heated or cooled in one portion of the system and then delivered in thermal contact with the target.

[0004] A preferred use of the heat transfer fluids of the present invention is for heat transfer with electrical or electronic equipment, particularly for removing excess heat generated by the function of electrical or electronic equipment. This application is of great industrial importance because electrical and electronic equipment typically perform optimally over a relatively narrow temperature range. These applications include thermostatic chambers and refrigeration circuits, as described in more detail below. In particular, the fluids of the present invention are dielectric fluids, and therefore are electrical insulators, capable of transferring heat to and from electrical and electronic equipment while in direct contact with the electronic equipment, such as wiring or integrated circuits. Furthermore, the use of dielectric fluids is particularly advantageous when these fluids are used in refrigeration circuits (described in more detail below) in which the fluid circulates in closed piping to avoid direct contact with conductive parts of the equipment, reducing the risk of damage to the electrical or electronic equipment in the event of a leak.

[0005] Computing equipment, such as computers and servers, generates a significant amount of heat. Large-scale developments that centralize many computers operating in a shared location, such as server farms, are becoming increasingly common. The industry for server farms, Bitcoin mining farms, and other supercomputing applications is growing extremely rapidly. A key factor in determining the construction strategy for such facilities is the control system that allows heat to be exchanged with such computing equipment. This system, often referred to as a "thermal management system," is typically used to cool computing equipment during operation, but can also be used for heating, such as when starting up a system in a cold environment. While air remains the most commonly used fluid, it has the disadvantage of requiring large air gaps between electronic boards, resulting in a very large footprint. Air cooling also requires large air conditioning engines, whose energy consumption is significant and accounts for a significant portion of the running costs of such facilities.

[0006] Recently, solutions for server thermal management based on the use of heat transfer fluids, especially liquid heat transfer fluids, have attracted great interest because they are energy efficient (using less energy than traditional air conditioning systems) and allow more servers, processors, and circuit boards to be accommodated in a smaller space.

[0007] Other important specialized applications of heat transfer fluids can be found, for example, in the semiconductor industry (TCU, thermostatic ovens, vapor phase soldering) and in the battery industry, especially in the vehicle battery industry for thermal management systems.

[0008] There are a variety of heat transfer fluids used industrially in a variety of applications; however, the selection of the appropriate fluid can be important in some applications. Some heat transfer fluids commonly used in the past are no longer practical due to their toxicity (ammonia, ethylene glycol), while others have been phased out due to their environmental profile, being non-biodegradable and / or believed to be harmful to the Earth's ozone layer and / or to act as greenhouse gases when dispersed in the environment.

[0009] Fluorinated liquids are very effective heat transfer fluids. Commercially available products exist, such as Solvay's Galden® and 3M's Fluorinert™: they are liquid polymers or oligomers that are dielectric, have high heat capacity, low viscosity, are non-toxic, and are chemically inert, so they can be in direct contact with electronic substrates and do not chemically interact with most materials. A drawback associated with these fluorinated fluids used to date is their high GWP values.

[0010] GWP (Global Warming Potential) is a property that can be determined for a given compound (considering "1" as a baseline value for CO2) that indicates how much heat a given greenhouse gas can trap in the atmosphere, calculated over a specific time interval, typically 100 years (GWP 100 ).

[0011] GWP 100 The determination of GWP is done by combining experimental data on the atmospheric lifetime of the compound with its radiative efficiency using special computational tools, which is standard in the art and is described for example in the comprehensive review published by Hodnebrog et al. in Review of Gephysics, 51 / 2013, p300-378. Very stable halogenated molecules such as CF4 and chloro / fluoroalkanes have very high GWPs. 100 (7350 for CF4 and 4500 for CFC-11).

[0012] Over the years, heat transfer fluids with high GWP values ​​have been phased out in industry, and lower GWP 100 Replaced by compounds with the lowest possible GWP 100 There continues to be a continuing interest in heat transfer fluids that have value.

[0013] Hydrofluoroethers, especially segregated hydrofluoroethers, have a relatively low GWP 100 On the other hand, other of their properties can be compared to the properties of CFCs used in the past, and for this reason some hydrofluoroethers are popularly used industrially as heat transfer fluids, for example marketed by 3M under the trade name "Novec®".

[0014] Hydrofluoroethers have been widely described as heat transfer media due to their wide temperature range over which they are liquid, and their low viscosity over a wide range of temperatures, making them useful for application as low-temperature secondary refrigerants for use in secondary loop cooling systems where the viscosity should not be too high at operating temperatures.

[0015] Fluorinated ethers are described, for example, by 3M in U.S. Pat. No. 5,713,211, by Dupont in U.S. Pat. Appl. Pub. No. 2007 / 0187639, and by Solvay Solexis SpA in WO 2007 / 099055 and WO 2010034698.

[0016] However, as shown in U.S. Pat. No. 5,713,211 (Table 5), the GWP of segregated hydrofluoroethers 100 is much lower than CFCs, but still in the range of 70-500.

[0017] [Table 1]

[0018] Other hydrofluoroolefins are commercialized as heat transfer fluids, for example by Chemours (Opteon™). These compounds have a very low GWP of about 1, but unlike the compounds cited above, they are much more flammable, which therefore limits their field of use.

[0019] International PCT Patent Application No. EP2020 / 057121 to Solvay Specialty Polymers Italy SpA generally describes the use of halogenated vinyl ethers as heat transfer fluids having low GWP, low flammability, and good dielectric properties and heat capacity. However, there are also other halogenated vinyl ethers that have an even better balance of good thermal and dielectric properties, are liquid over a wide temperature range, are non-flammable, and have very low GWP. 100 There is a continuing need to provide more effective methods for efficient heat transfer using heat transfer fluids having a viscosity of 30 or less. Summary of the Invention

[0020] The present invention relates to a method for exchanging heat with a body, comprising using a heat transfer fluid, said heat transfer fluid comprising one or more fluorinated nitro compounds of the following general formula (I): [ka] (In the formula: at least two of R1, R2, R3, and R4 are independently selected from H, Cl, and F, provided that at least one is H or Cl; R1, R2, R3, and R4, which are not H, F, or Cl, are selected from partially halogenated alkyl and fully halogenated alkyl, the alkyl chain being C1-C4 and the halogen being selected from Cl and F). DETAILED DESCRIPTION OF THE INVENTION

[0021] By "electronic computing equipment" is meant any individual or array of individual computer boards, including microprocessor CPUs, GPUs, SSDs, and DDR memory, that perform computational tasks, and thus includes not only large server farms, internet servers, and bitcoin mining factories, but also small individual computers, internet servers, and computer gaming machines. Both large and small scale installations can benefit from the heat transfer methods of the present invention.

[0022] The term "semiconductor device" in this invention includes any electronic device that utilizes the properties of semiconductor material. Semiconductor devices are fabricated both as single devices and as integrated circuits consisting of many interconnected devices (starting from two and going up to billions) fabricated on a single semiconductor substrate or "wafer." The term "semiconductor device" includes both basic building blocks, such as diodes and transistors, to complex structures constructed from these basic blocks, ranging from analog, digital, and mixed-signal circuits, such as processors, memory chips, integrated circuits, circuit boards, phototubes and solar cells, sensors, etc. The term "semiconductor device" also includes any intermediate or unfinished product in the semiconductor industry derived from a wafer of semiconductor material.

[0023] The present invention relates to a method for exchanging heat with a body comprising using a heat transfer fluid, wherein the heat transfer fluid comprises one or more compounds having the general formula: [ka] (In the formula: at least two of R1, R2, R3, and R4 are independently selected from H, Cl, and F, provided that at least one is H or Cl; R1, R2, R3, and R4, which are not H, F, or Cl, are selected from partially halogenated alkyl and fully halogenated alkyl, the alkyl chain being C1-C4 and the halogen being selected from Cl and F).

[0024] In the above general formula (I), if present, the partially halogenated alkyl and fully halogenated alkyl are preferably fluorinated, more preferably having a carbon chain of C1 to C3, even more preferably C1. A particularly preferred fully fluorinated alkyl is -CF3.

[0025] In particularly preferred embodiments, the heat transfer fluids of the present invention comprise one or more compounds of general formula (I) wherein at least two of R 1 , R 2 , R 3 , and R 4 are F.

[0026] Also, in a particularly preferred embodiment, the heat transfer fluid of the present invention comprises one or more compounds of general formula (I) in which at least one of R1, R2, R3, and R4 is Cl, more preferably two of R1, R2, R3, and R4 are Cl.

[0027] This class of compounds can be synthesized starting from common fluoroolefins and hydrofluoroolefins (HFOs) via nitrofluorination reactions, which are described in more detail below. When olefins containing a C=C double bond undergo nitrofluorination, the double bond becomes saturated, with one -NO2 radical added to one of the carbon atoms that make up the double bond and an -F radical added to the other.

[0028] The nitro group can be attached to either one or the other of the two carbon atoms forming the double bond. As a result, the nitrofluorination of asymmetric olefins can produce a mixture of two different isomers. In the mixture, one of the two compounds can be present in greater amounts than the other. Without being bound by theory, it is believed that both the polarity of the double bond and the effect of steric hindrance play a role in the selectivity of the reaction.

[0029] Nitrofluorination of olefins is a known process and is described, for example, in Knunyants, IL, German, LS, & Rozhkov, IN (1963). "Aliphatic fluoro nitro compounds Communication 1. Conjugated nitrofluorination of olefins." Bulletin of the Academy of Sciences, USSR Division of Chemical Science, 12(11), 1794-1797. https: / / doi.org / 10.1007 / BF00843794. However, the nitrofluorination reaction leading to the preparation of the nitro compounds of the present invention has not been described.

[0030] Nitrofluorination of fluorinated compounds can be carried out as is commonly known for other olefins. Preferably, the nitrofluorination reaction to prepare the fluorinated olefins of the present invention comprises: Preparation of 1-nitro / fluoro mixtures, and Reactions of 2-halogenated olefins with nitro / fluoro mixtures It is carried out in two stages.

[0031] Step 1. Preparation of the nitro / fluoro mixture Nitro / fluoro mixtures for the present invention can be prepared using several different methods, including but not limited to the following: a- Mix pure nitric acid and anhydrous hydrogen fluoride in a molar ratio of 1:1 or greater (HF / HNO3). (The preferred molar ratio range is 5:1 to 10:1.) b-Carbonyl difluoride is reacted with nitric acid to form a nitro / fluoro mixture as in method "a".

[0032] Step 2 - Reaction of halogenated olefins with nitro / fluoro mixtures The halogenated olefin is slowly added in a stoichiometric ratio or a slight excess to the nitro / fluoro mixture contained in a metal reactor. The internal temperature is carefully monitored. The reaction is allowed to proceed while the reactor is maintained at a temperature ranging from 20 to 120°C for 3 to 24 hours. The temperature selected depends on the olefin selected and its reactivity and stability. Generally, temperatures below 20°C are too slow, while temperatures above 120°C may cause instability with certain olefins. At the end of the reaction, the reactor is emptied and the crude product is separated and purified.

[0033] The nitrofluorination reaction can be carried out in a pressurized reactor or in an atmospheric stirred tank reactor.

[0034] The described nitrofluorination method should not be considered limiting, and those skilled in the art will be able to make changes and modifications to the method, in particular to scale up the method for industrial application, according to conventional chemical engineering procedures.

[0035] The method of the present invention can be used to exchange heat with any object. It is particularly useful when the object is electronic computing equipment, such as a computer server. Indeed, the method of the present invention can also be used in systems using so-called "immersion cooling" or "direct contact cooling" because it uses a stable, dielectric, non-flammable, and non-corrosive heat transfer fluid. In these systems, the fluid is placed in direct contact with the electronic circuit board. Such fluids at their operating temperatures can be gases, liquids (single-phase immersion cooling), or in vapor-liquid equilibrium (i.e., near the boiling point of the liquid in so-called "two-phase immersion cooling").

[0036] In immersion cooling, electronic computing equipment such as CPUs, GPUs, memory, and other electronics, including complete servers, are completely immersed in a thermally conductive dielectric liquid or coolant, and its temperature is controlled using a circulation system that pumps the liquid through piping to a heat exchanger or radiator-type cooling device that rejects heat from the coolant.

[0037] Immersion cooling of servers is becoming a popular solution for server cooling, as it allows for significant reductions in energy usage by eliminating expensive air conditioning equipment. These systems are replaced with efficient low-speed liquid circulation pumps and simpler heat exchanger and / or radiator systems.

[0038] The temperature used in immersion cooling is determined by the maximum temperature at which the immersed equipment can reliably operate. For servers, this temperature range is typically 15-65°C, although in some cases this range can be extended to 75°C.

[0039] Current commercial applications of immersion cooling span data center-oriented solutions for commodity server cooling, server clusters, HPCC applications, and Bitcoin mining, as well as mainstream cloud-based and web hosting architectures. Immersion cooling is also used in the thermal management of computing equipment associated with LEDs, lasers, X-ray machines, and magnetic resonance imaging devices.

[0040] The method of the present invention is suitable for both single-phase and two-phase immersion cooling. In a single-phase immersion cooling system, the server is immersed in a bath of dielectric fluid. Heat is transferred to the fluid through direct contact with the electronic components. The fluid is usually maintained at a constant temperature through a recirculation system typical of a thermostatic bath. More or less sophisticated control systems may exist to control the instantaneous temperature of the fluid and the temperature of the server, optimizing the fluid temperature at each instant.

[0041] Two-phase immersion cooling is a technology sold by Allied Control and several other companies that involves submerging electronic devices in a sealed tank in a bath of dielectric fluid. This dielectric fluid has a boiling point that corresponds to a target temperature to which the bath can be set. When the electronic devices are heated to the boiling point of the dielectric fluid, the fluid transforms into a vapor, with heat subtracted from it. The vapor then condenses on a lid or coil condenser placed above the bath and re-deposits within the bath. This type of design is particularly valued because it does not require recirculation of the dielectric fluid and allows many more electronic devices to be accommodated in a small space.

[0042] The heat transfer fluids according to the present invention, i.e. comprising one or more compounds of general formula (I) as defined above, can be formulated with compounds having boiling points between 40°C and 90°C (see examples in the experimental section below) and are therefore particularly applicable to two-phase immersion cooling.

[0043] Furthermore, in the field of cooling computer equipment, the method of the present invention can also be used in non-immersion cooling systems in which a heat exchange fluid is circulated in a closed system and is in thermal contact with the processor through a plate of thermally conductive material (such as the server cooling solution manufactured by Ebullient under the name "Module Loop"). The use of a dielectric fluid, such as the heat transfer fluid of the present invention, is beneficial in any case, since there is always a risk of leakage and conductive liquids can have a destructive effect on electronic equipment.

[0044] The method of the present invention may also be useful in the semiconductor industry, where temperature control during the manufacture of semiconductor devices is critical. In this case, the object exchanging heat with the heat transfer fluid of the present invention is the semiconductor device. Temperature control units (TCUs) are used throughout the semiconductor device manufacturing line and can use the heat transfer fluid of the present invention to remove unwanted heat during steps such as wafer etching and deposition processes, ion implantation, and lithographic processes. The heat transfer fluid is typically circulated through the wafer mount and each process tool requiring temperature control has its own individual TCU.

[0045] Some particularly important tools that contain TCUs are silicon wafer etchers, steppers, and ashers. Etching is performed using reactive plasmas at temperatures ranging from 70°C to 150°C, and the wafer temperature must be precisely controlled throughout the temperature range during plasma processing. After plasma processing, the etched parts are usually immersed in a solvent that removes the etched portions. This second step usually does not require temperature control because it is performed at mild or ambient temperatures. When referring to an "etcher" in this application, it is intended to mean a device in which plasma processing at high temperatures is performed and therefore requires a TCU.

[0046] Steppers are used to photolithograph wafers to form reticle lines, which are then used to expose a photosensitive mask. This process is carried out at temperatures between 40°C and 80°C, and temperature control is crucial as the wafer must be maintained at a precise fixed temperature (±0.2°C) along the process to ensure good results.

[0047] Ashing is a process in which the photosensitive mask is removed from the wafer, performed at temperatures between 40°C and 150°C. The system uses plasma, and again, precise temperature control is particularly important.

[0048] Another related process is plasma-enhanced chemical vapor deposition (PECVD), in which a film of silicon oxide, silicon carbide, and / or silicon nitride is grown on the wafer in a chamber. Again, the temperature at which this step is carried out can be selected in the range of 50°C to 150°C, but the wafer must be held uniformly at the selected temperature throughout the deposition process.

[0049] In a semiconductor device manufacturing facility, typically each etcher, asher, stepper and plasma-enhanced chemical vapor deposition (PECVD) chamber has its own TCU, where application of the method of the present invention allows for recirculation of the heat transfer fluid of the present invention.

[0050] Another process step in which the heat transfer fluid of the present invention is used in the semiconductor device industry is vapor phase reflow (VPR) soldering. This is the most common method used to attach surface-mount devices, multichip modules, and hybrid components to circuit boards. In this method, the soldering material is applied in paste form, and then the semiconductor device, e.g., an unfinished circuit board, is placed in a sealed chamber containing a heat transfer fluid at its boiling point in equilibrium with its vapor phase. The vapor phase fluid transfers heat to the soldering paste, which then melts and stabilizes the contact. In this case, the fluid must be dielectric and noncorrosive, since it comes into direct contact with the circuit board. For this application, it is important that the heat transfer fluid contain a composition with a boiling point sufficient to melt the soldering paste. The heat transfer fluid of the present invention can also be used in this process.

[0051] Another system that is an important part of the manufacturing process for many semiconductor devices is thermal shock testing. In thermal shock testing, semiconductor devices are tested at two very different temperatures. While different standards exist, the test generally involves subjecting the semiconductor device to high and low temperatures and then testing the device's physical and electronic properties. Typically, the semiconductor device to be tested is directly immersed alternately in a high-temperature bath (which can be at temperatures between 60°C and 250°C) and a low-temperature bath (which can typically be at temperatures between -10°C and -100°C). The time required to move between the two baths must be minimized, usually less than 10 seconds. Furthermore, in this test, the fluid comprising the bath comes into direct contact with the device and therefore must be dielectric and noncorrosive. Additionally, to avoid contamination of the baths, it is highly preferred that the same fluid be used in both the low-temperature and high-temperature baths. Therefore, a heat transfer fluid that exists as a liquid over a wide temperature range is preferred. In this case, the heat transfer fluid according to the present invention can be used in this process.

[0052] Heat transfer fluids for use in the manufacture of semiconductor devices are typically liquids that exist in the liquid state over a wide temperature range, are dielectric, non-corrosive, and have relatively low viscosities that make them easily pumpable.

[0053] The method of the present invention can be used in all steps of semiconductor device manufacturing where the semiconductor device requires heat exchange with a heat transfer fluid, particularly when semiconductor processing equipment such as etchers, ashers, steppers, and plasma-enhanced chemical vapor deposition (PECVD) chambers are used, each of which requires precise temperature control and / or heat dissipation and therefore includes a temperature control unit (TCU) that can contain the selected heat transfer fluid of the method of the present invention.

[0054] In addition, during thermal shock testing, which is an essential part of semiconductor device manufacturing, only devices that pass the test are further processed, and thus semiconductor devices are cooled and heated using at least two baths made of heat transfer fluids: a low-temperature bath, typically at a temperature of -10 to -100°C, and a high-temperature bath, typically at a temperature of 60 to 250°C. Advantageously, the method of the present invention can be carried out by selecting an appropriate compound or blend of compounds of general formula (I) that constitutes the heat transfer fluid for the baths. Preferably, the heat transfer fluid should be selected so that the same heat transfer fluid can be used in both baths due to the wide temperature range over which the fluid is in a liquid state, so that there is no risk of cross-contamination of the baths.

[0055] The method of the present invention can also find application in vapor phase soldering; indeed, the selected heat transfer fluid of the method of the present invention can be formulated to have a boiling point along the boiling point of the soldering paste, so that a semiconductor device containing a soldering paste that must further be "cured" can be introduced into a sealed chamber containing the selected heat transfer fluid of the method of the present invention at its boiling point in equilibrium with its heated vapor phase. The heated vapor will transfer heat to the semiconductor device, thereby melting the soldering paste and thus securing the contacts as required. For this application, a high-boiling point compound of the general formula must be used in the heat transfer fluid:

[0056] An additional advantage is the ability to use a single heat transfer fluid for multiple applications, potentially enabling the use of a single heat transfer fluid throughout an entire semiconductor device manufacturing facility.

[0057] Another area in which the method of the present invention may be useful is in the thermal management of batteries, particularly rechargeable batteries such as vehicle batteries for automobiles, trams, trains, etc.

[0058] Recently, much of the industry-wide development in the field of rechargeable batteries has focused on lithium-ion batteries based on different types of lithium salts. Batteries based on lithium manganese oxide, lithium iron phosphate, and lithium nickel manganese cobalt oxide are used in applications such as vehicles, power tools, and electric bicycles. Lithium cobalt oxide-based batteries are typically used in smaller, less intensive applications, such as mobile phones, portable computers, and cameras. Batteries based on lithium nickel cobalt aluminum oxide and lithium titanate are being considered for applications requiring high power and / or capacity, such as electric powertrains and grid storage. Naturally, new technologies outside the realm of lithium-ion batteries are also being explored and constantly developed. The method of the present invention is not tied to a specific battery technology and is applicable to both current and next-generation battery systems.

[0059] Unlike conventional power systems, batteries, and particularly rechargeable batteries, have stringent requirements for their operating environment: Batteries tend to operate best within a relatively narrow temperature range.

[0060] Generally, low temperatures affect the chemical properties of the battery, slowing down reaction rates and therefore reducing the flow of electricity during charging or discharging. High temperatures increase reaction rates while also increasing energy dissipation, thus generating even more excess heat, potentially causing an uncontrolled increase in temperature and potentially irreversible damage to the cell. In a typical Li-ion battery, temperatures exceeding 80°C in even a portion of its structure can initiate exothermic chemical reactions that cause further temperature increases in the battery, ultimately resulting in the complete destruction of the battery and the risk of fire and explosion.

[0061] On the other hand, practical applications of batteries require them to be efficient over a much wider temperature range. For example, vehicle batteries need to function properly in any environment in which people are expected to use them, and so they need to operate over a temperature range of -20°C to +40°C or more. In addition, the charge and discharge cycles of a battery can generate heat in the battery itself, making it even more difficult to maintain the battery within an acceptable temperature range.

[0062] Typical Li-ion battery performance figures indicate that while the usable temperature range is typically between -20°C and 60°C, good power output is only achieved between 0°C and 40°C, with optimal performance occurring between 20°C and 40°C. Temperature also affects battery life; in fact, the number of charge / discharge cycles a battery can withstand before being considered depleted drops rapidly below 10°C due to anode plating and above 60°C due to electrode material degradation. The temperature range for optimal performance may vary for different battery chemistries and constructions; however, all current commercial batteries share a relatively narrow temperature range over which their performance is optimal. It is also generally important to ensure that the entire battery is maintained uniformly at the same temperature, without hot or cold regions, which can reduce its lifespan and safety.

[0063] For this reason, it is now common practice to incorporate battery thermal management systems (BTMS) into commercial battery assemblies, especially when battery safety, reliability, and lifespan are important concerns. These BTMS can be more or less complex depending on the type of battery; however, one common element is the presence of a heat transfer fluid, such as a gas or liquid, that exchanges heat with the battery, thus heating or cooling it.

[0064] Therefore, battery thermal management systems (BTMS) are particularly important in applications requiring high power and high reliability, such as vehicle batteries. While BTMSs can be more or less complex depending on the application, each BTMS at least functions to cool the battery when its temperature is too high or to heat the battery when its temperature is too low, typically using a heat transfer fluid that exchanges heat with the battery. Other common features of BTMSs are an insulation system to reduce the effect of the external environment on the battery temperature and a ventilation system to facilitate the dissipation of hazardous gases that may be present within the battery pack. However, the method of the present invention, which specifically relates to the heat exchange function of the BTMS, can be easily applied to any BTMS and can incorporate other functions and features.

[0065] BTMSs that use liquids as heat transfer fluids are common because liquids can transfer greater amounts of heat more quickly than gases. Typically, the fluid is circulated by a pump in a sealed system that is in thermal contact with the battery and a second system that functions to heat and / or cool the fluid to a desired temperature. This second system can include any combination of a cooling system and a heating system, or it can combine heating and cooling functions in a heat pump. The circulating fluid absorbs heat from or releases heat to the battery, and then it is circulated in the second system, returning the fluid to the desired temperature. There can be more or less sophisticated control systems that control the temperature of the fluid and the temperature of the battery to optimize the fluid's temperature at each instant.

[0066] In some systems, the heat transfer fluid can be in direct contact with the battery cells that are subsequently immersed therein. Clearly, in these cases, the fluid must be dielectric to protect the battery cells and their electronic components. In other cases, the heat transfer fluid is circulated in a separate, sealed system that simply exchanges heat by indirect contact, for example, through heat exchange plates made of metal or other thermally conductive materials. Since sealed systems have a high risk of leaks in any case, a dielectric fluid can also be advantageous in this type of system.

[0067] Particularly for high power batteries, where thermal management systems based on fluids, especially liquids, are used, the method of the present invention provides a reduced GWP 100 This provides improved thermal management in

[0068] Heat transfer fluids according to the present invention may be useful as heat transfer fluids in BTMS.

[0069] Beyond the listed applications, the method of the present invention can also be adapted to any heat exchange method, such as heating or cooling compartments (e.g. food compartments), including those on aircraft, vehicle, or ship substrates, heating or cooling industrial production equipment, heating or cooling batteries during operation, forming thermostatic baths.

[0070] As mentioned in the introduction, heat transfer fluids used in these fields include fluorinated compounds. Hydrofluoroethers in particular have found application in these fields due to their chemical inertness, dielectric properties, the fact that they are liquids and pumpable (typically having a viscosity of 1-50 cps at the temperature of use), a wide T range, low flammability, and relatively low GWP.

[0071] Commercially available hydrofluoroethers for use in these areas, for example, combine all these properties with a relatively low GWP of about 70 to 300. 100 It is from 3M's Novec™ series, which combines

[0072] Furthermore, GWP has also become an important property in recent years due to the regulatory environment, and therefore there is a constant demand to develop new heat exchange fluids with even lower GWP than the currently commercialized hydrofluoroethers.

[0073] Applicant has surprisingly found that the heat transfer fluids used in the method of the present invention are non-flammable, provide efficient heat transfer, can be used over a wide temperature range, and have dielectric and thermal properties that are equal to or improved over other materials commercialized as heat transfer fluids. Surprisingly, the heat transfer fluids used in the present invention have extremely low GWPs, generally below 30 and for some materials even below 3, as shown below in the experimental section. 100 This is a particularly unexpected result, and indeed previous reviews such as Hodnebrog et al. cited above did not study or suggest fluorinated compounds bearing nitro groups as low GWP compounds.

[0074] Therefore, using these selected compounds according to general formula (I), a GWP of less than 30, preferably less than 10, and even more preferably less than 5 can be achieved. 100 Heat transfer fluids having high thermal conductivity can be formulated. Heat transfer fluids according to the present invention also have low toxicity and exhibit good heat transfer properties over a wide range and relatively low viscosity. Fluids of the present invention also have excellent electrical compatibility, i.e., they are non-corrosive, have high dielectric strength, high volume resistivity, and low solvency for polar materials. The electrical properties of the fluids of the present invention are such that they can be used in immersion cooling systems for electronics in direct contact with circuitry as well as in indirect contact applications using loops and / or conductive plates.

[0075] Heat transfer fluids for use in the process of the present invention preferably comprise more than 5% by weight, more preferably more than 50% by weight, and even more preferably more than 90% by weight of one or more compounds of formula (I) as defined above. In one embodiment, the heat transfer fluid consists entirely of one or more compounds of general formula (I).

[0076] In some embodiments, the heat transfer fluids of the present invention comprise a blend of compounds of the general formula:

[0077] In another aspect, the present invention also encompasses an apparatus comprising electronic computing equipment and a heat transfer fluid comprising one or more fluorinated nitro compounds of general formula (I) as defined above.

[0078] In a further aspect, the present invention relates to a device comprising a battery, preferably a rechargeable battery, and a thermal management system for said battery, said thermal management system comprising a heat transfer fluid for exchanging heat with said battery, said heat transfer fluid comprising one or more fluorinated nitro compounds of general formula (I) as defined above.

[0079] To the extent that the disclosure of any patents, patent applications, and publications incorporated herein by reference contradicts the statements of this application to the extent that a term may be unclear, the statements of this application shall control.

[0080] The present invention will now be described in more detail with reference to the following examples, the purpose of which is merely illustrative and not intended to limit the scope of the invention.

[0081] standard: Electrical properties are measured according to the following standards: Dielectric Constant - ASTM D924-15 Specific Heat Capacity - ASTM E1269 I followed the instructions. [Example]

[0082] Nitrofluorination was carried out on fluoroolefins according to the following general formula (I): A1112(1,2-Dichloro-1,2-difluoroethylene) TrFE (trifluoroethylene)

[0083] The nitrofluorination reaction was carried out in a stainless steel reactor (internal volume 0.6 L) charged with 6.7 moles of AHF (anhydrous hydrogen fluoride) and 0.73 moles of WFNA (white fuming nitric acid >95%) transferred under vacuum. The contents were stirred and the temperature was raised to the temperature shown in the table below.

[0084] Then, a steel cylinder containing 0.6 moles of olefin was connected to the reactor using metal joints and valves, and the connecting valve was then opened to allow the olefin to flow into the reactor.

[0085] The system was maintained at constant temperature for the time indicated in the table below, and then the reactor was cooled to room temperature, after which the reactor contents were transferred to a mixture of water and ice (1180 g) in a plastic wash bottle.

[0086] The organic phase was then separated from the water / ice mixture and washed twice with 10% potassium hydroxide solution using a plastic separatory funnel, followed by drying over anhydrous magnesium sulfate.

[0087] Finally, after filtration to remove residual magnesium sulfate, the organic phase was distilled on a 30 cm, 14 mm diameter Hempel column equipped with a Rahisch ring and reflux condenser.

[0088] The resulting material was analyzed by 19F-NMR spectroscopy.

[0089] Table 1 summarizes the reaction conditions and the resulting products.

[0090] [Table 2]

[0091] Chemical names of nitrofluorinated products: A1112: NCFC-113 = 1,2-dichloro-1,1,2-trifluoro-2-nitroethane TrFE: NHFC-124 = 1,1,1,2-tetrafluoro-2-nitroethane

[0092] The resulting nitro compounds were tested for their flammability (all were found to be neither flammable nor combustible).

[0093] The compounds of the present invention surprisingly have good specific heat capacities, ensuring more efficient heat transfer. This is combined with other desirable properties comparable to other materials (non-flammability, low GWP, and very low dielectric constant). This combination of properties makes the materials of the present invention particularly suitable as heat transfer fluids. Heat transfer fluids containing these compounds can be used in all of the applications mentioned, including heat exchange with electronic computing equipment, batteries, or semiconductor devices.

Claims

1. 1. A method for exchanging heat with a body comprising using a heat transfer fluid, said heat transfer fluid comprising one or more fluorinated nitro compounds of the following general formula (I): 【Chemical 1】 (In the formula: at least two of R1, R2, R3, and R4 are independently selected from H, Cl, and F, provided that at least one is H or Cl; R1, R2, R3, and R4, which are not H, F, or Cl, are selected from partially halogenated alkyl and fully halogenated alkyl, and the alkyl chain is C １ ~C ４ and the halogen is selected from Cl and F.

2. 2. The method of claim 1, wherein the one or more fluorinated nitro compounds comprise at least 5% by weight of the heat transfer fluid, preferably greater than 50% by weight, and more preferably greater than 90% by weight.

3. The heat transfer fluid has a GWP, determined according to the method reported in Hodnebrog et al., Review of Geophysics, 51 / 2013, pp. 300-378, of less than 30, preferably less than 10, more preferably less than 5. １００ 3. The method of claim 1 or 2, comprising:

4. The method of any one of claims 1 to 3, wherein the object is an electronic computing device.

5. The method of claim 4 , wherein the electronic computing device is one or more servers.

6. 6. The method of claim 4 or 5, wherein the electronic computing device includes one or more electronic circuit boards, the method comprising directly contacting the electronic circuit boards with the heat transfer fluid.

7. The method according to any one of claims 4 to 6, which is a single-phase immersion cooling method.

8. The method according to any one of claims 4 to 6, which is a two-phase immersion cooling method.

9. The method according to any one of claims 1 to 3, wherein the object is a battery, preferably a rechargeable battery, more preferably a rechargeable vehicle battery.

10. The method of any one of claims 1 to 3, wherein the object is a semiconductor device.

11. 11. The method of claim 10, using one or more of semiconductor processing equipment selected from an etcher, an asher, a stepper, and a plasma-enhanced chemical vapor deposition (PECVD) chamber, the semiconductor processing equipment including at least one temperature control unit (TCU) in heat exchange with the semiconductor device, the TCU containing the heat transfer fluid.

12. 11. The method of claim 10, which is a method for thermal shock testing of a semiconductor device, the method comprising, in any order: i. cooling said semiconductor device to a temperature comprised between −10° C. and −100° C. using a first bath made of a first fluid; ii. Heating the semiconductor to a temperature comprised between 60°C and 250°C using a second bath made of a second fluid; Including, A method wherein one, or preferably both, of said first and second fluids is a heat transfer fluid according to any one of claims 1 to 3.

13. 11. The method of claim 10, which is a vapor phase soldering method for semiconductor devices, said method comprising: i. providing a semiconductor device containing a soldering paste; ii. providing an enclosed chamber containing the heat transfer fluid at its boiling point such that heated vapor of the heat transfer fluid is produced within the enclosed chamber; iii. introducing the semiconductor device into the sealed chamber in contact with the vapor of the heat transfer fluid, thereby melting the soldering paste upon contact with the heated vapor; A method comprising:

14. 1. An apparatus comprising an electronic computing device and a heat transfer fluid, said heat transfer fluid comprising one or more fluorinated nitro compounds of the following general formula (I): 【Chemistry 2】 (In the formula: at least two of R1, R2, R3, and R4 are independently selected from H, Cl, and F, provided that at least one is H or Cl; R1, R2, R3, and R4, which are not H, F, or Cl, are selected from partially halogenated alkyl and fully halogenated alkyl, and the alkyl chain is C １ ~C ４ and the halogen is selected from Cl and F.

15. 1. An apparatus comprising a battery, preferably a rechargeable battery, and a thermal management system for said battery comprising a heat transfer fluid for exchanging heat with said battery, said heat transfer fluid comprising one or more fluorinated nitro compounds of the following general formula (I): 【Chemistry 3】 (In the formula: at least two of R1, R2, R3, and R4 are independently selected from H, Cl, and F, provided that at least one is H or Cl; R1, R2, R3, and R4, which are not H, F, or Cl, are selected from partially halogenated alkyl, fully halogenated alkyl, and the alkyl chain is C １ ~C ４ and the halogen is selected from Cl and F.

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