A coolant for cooling an element by direct immersion cooling

Abstract

A coolant for cooling electrical / electronic components by direct immersion cooling, comprising a partially fluorinated ether having the structure of (compound (1)). R1, R2, R3, and R4 are independently selected from the group consisting of H, F, Cl, Br, I, CF3, alkyl, fluoroalkyl, and haloalkyl, and R5 is independently selected from the group consisting of CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl, and perfluorohaloalkyl.

Description

[Technical Field]

[0001] This invention relates to a coolant for cooling electrical / electronic components by direct immersion cooling, comprising a portion of a fluorinated ether. [Previous Technology]

[0002] The enumeration or discussion of previously published literature or any background in this specification shall not be construed as an admission that such literature is part of the prior art or is common knowledge.

[0003] Numerous problems exist related to large-scale computing facilities, and to their effective power utilization. These facilities typically have high power density. These problems include the requirement for specialized buildings to provide temperature-controlled environments. It has also been found that the practicality associated with the power density of installed equipment can affect, or conversely, be limited by, the available building size. These factors negatively influence the determination (limitation) of the performance of computing facilities.

[0004] Typically, air cooling systems are used to cool computing facilities, such as data centers. Unfortunately, using air as a cooling medium not only provides poor heat transfer efficiency but also requires specific flow conditions, which may necessitate certain building designs. It has been observed that approximately 45% of all power in data centers is used for cooling. Therefore, there is an urgent need to reduce power consumption by improving cooling efficiency. Improved cooling media are also needed.

[0005] Furthermore, in recent years, there has been an increasing shift from conventional fossil fuel-powered automobiles and other vehicles to vehicles that are at least partially, and in some cases, entirely, electrically powered. These "electric" vehicles typically include an energy storage system (such as a battery pack) and electric drive system components (including power electronics and one or more electric motors). Typically, these components require thermal management during use to ensure they operate most efficiently without damage.

[0006] Indeed, there is a driving force that can charge the battery packs of such vehicles much faster without causing damage; until now, such fast charging has been limited by the inability of conventional battery cooling and / or heating systems to provide adequate thermal management. Some of these thermal management systems must be based on aqueous / aqueous derivative systems (e.g., water or water / diol) systems because of their high heat capacity. However, such aqueous components are clearly incompatible with electrical components (due to their high dielectric constant), which means that complex and inefficient separation and thermal management interfaces are required. [Summary of the Invention]

[0007] One object of the present invention is to solve the above-mentioned defects.

[0008] According to a first aspect of the present invention, a coolant for cooling electrical / electronic components by direct immersion cooling is provided, comprising a partially fluorinated ether having the structure of (compound (1)).

[0008]

[0008] R1, R2, R3, and R4 are independently selected from the group consisting of H, F, Cl, Br, I, CF3, alkyl, fluoroalkyl, and haloalkyl, and R5 is independently selected from the group consisting of CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl, and perfluorohaloalkyl.

[0009] According to a second aspect of the present invention, an insulating medium for an electrical / electronic component is provided by at least partially directly immersing the component in the component, comprising a partially fluorinated ether having the structure of (compound (1)).

[0009]

[0010] R1, R2, R3, and R4 are independently selected from the group consisting of H, F, Cl, Br, I, CF3, alkyl, fluoroalkyl, and haloalkyl, and R5 is independently selected from the group consisting of CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl, and perfluorohaloalkyl.

[0011] Preferably, the compositions of the first and second states are substantially free of water. The term "free of water" means that the composition is completely free of water or has a low water content of less than about 1000 ppm, more preferably less than 500 ppm, more preferably less than 300 ppm, more preferably less than 200 ppm and most preferably less than 100 ppm.

[0012] The components of the first and second states may contain a desiccant. Alternatively, the components used with the components may have a desiccant incorporated therein or adapted to operate therewith. For example, electrical components may be configured or adapted to incorporate a replaceable, as appropriate, desiccant-containing cartridge.

[0013] In the composition of the first and second states, preferably R5 is methyl; preferably R1 is CF3 and R2 to R4 are all H; or, R1 is CF3, R2 is H, one of R3 and R4 is F, and one of R3 and R4 is H.

[0014] The composition of the first and second states preferably further comprises a non-flammable (partial or complete) fluorinated ether and / or a non-flammable (partial or complete) fluorinated ketone. Suitable fluorinated ethers include partially or perfluorinated butylalkyl ethers, such as C4F9OCH3 (1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane); HFE7100 commercially available under the trade names "Novec 7100" and C4F9OC2H5 (1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane); and HFE7200 commercially available under the trade name "Novec 7200". Preferred examples of (partial or complete) fluorinated ketones 1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone and the structural formula CF3CF2C(=O)CF(CF3)2 are commercially available under the trade name "Novec 1230". Such fluids are available from 3M.

[0015] It has been found that by incorporating such fluorinated ethers or ketones, the flammability of the composition can be significantly reduced or made non-flammable. Furthermore, it has been found that the partially fluorinated ethers of this composition have higher specific heat capacities and lower liquid viscosities compared to (partial or complete) fluorinated ethers and / or (partial or complete) fluorinated ketones (such as Novec 7100 or 7200). This means that mixtures comprising the partially fluorinated ethers of the present invention and (partial or complete) fluorinated ethers and / or (partial or complete) fluorinated ketones have been found to exhibit excellent performance as heat transfer fluids. The higher heat capacity allows for a reduction in the mass flow rate required to achieve a given cooling load. This reduced mass flow rate, combined with (alternatively observed) lower viscosity, increases the local heat transfer rate; and for flow systems, it also reduces the energy required to overcome pressure drops when pumping coolant around the cooling loop.

[0016] Preferably, the composition of the first and second states comprises 1 to 99 wt% (of compound (1)) partially fluorinated ether and 1 to 99 wt% (partial or total) fluorinated ether and / or (partial or total) fluorinated ketone. More preferably, the composition comprises 10 to 80 wt% (of compound (1)) partially fluorinated ether and 90 to 20% (partial or total) fluorinated ether and / or (partial or total) fluorinated ketone. More preferably, the composition comprises 20 to 70 wt% (of compound (1)) partially fluorinated ether and 80 to 30% (partial or total) fluorinated ether and / or (partial or total) fluorinated ketone. More preferably, the composition comprises 30 to 60 wt% (of compound (1)) partially fluorinated ether and 70 to 40% (partial or total) fluorinated ether and / or (partial or total) fluorinated ketone. More preferably, the composition comprises 40 to 50 wt% (of compound (1)) of partially fluorinated ether and 60 to 50 wt% of (partial or total) fluorinated ether and / or (partial or total) fluorinated ketone.

[0017] Suitably, the composition contains sufficient (partial or all) fluorinated ethers and / or (partial or all) fluorinated ketones to make the composition non-flammable.

[0018] Particularly preferred components of the present invention are a binary mixture of 1,1,1,3-tetrafluoro-2-methoxypropane ("ether A") or 1,1,1,3,3-pentafluoro-2-methoxypropane ("ether B") (both compounds (1)) and C4F9OCH3 (1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane). At temperatures within the intended operating range of the immersion coolant, both ether A and ether B form an azeotropic or near-azeotropic mixture with C4F9OCH3. This means that even when used as a two-phase coolant undergoing vaporization and condensation processes, the composition of the mixture remains unchanged (or changes negligibly).

[0019] Preferred examples of electrical / electronic components include medium- or high-voltage power transmission components, such as those used for / for supplying power from a power plant to residential / commercial users. Therefore, according to a third embodiment of the invention, by at least partially immersing the component, an insulating medium for medium- or high-voltage power transmission components is provided, comprising a partially fluorinated ether having the structure of (compound (1)).

[0019]

[0020] R1, R2, R3, and R4 are independently selected from the group consisting of H, F, Cl, Br, I, CF3, alkyl, fluoroalkyl, and haloalkyl, and R5 is independently selected from the group consisting of CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl, and perfluorohaloalkyl.

[0021] The elements of the first and second versions of the present invention should be regarded as applicable to the third version of the present invention in practice.

[0022] The composition of the third state of the present invention has been found to be advantageous because it exhibits high dielectric strength and thus serves as an effective insulator. It has been found that when measured across a 0.1" (2.5 mm) gap, the dielectric strength exceeds 1 kV, more preferably 5 kV, more preferably 10 kV, more preferably 15 kV, such as 18 kV or even 20 kV. It has also been found to serve as an effective arc-preventing agent (and therefore as an arc-quenching agent).

[0023] A further advantage of this composition is that it is non-toxic and inert. Compared to typical compositions previously used for this purpose (sulfur hexafluoride, SF6), the composition of the third state of the present invention has a low global warming potential (GWP). Historically, the GWP of SF6 used was 23,500.

[0024] Preferred examples of medium- or high-voltage electrical transmission elements include MV / HV transformers, circuit breakers, switchgear, and gas-insulated lines.

[0025] Another preferred example of an electrical / electronic component includes components used in electric vehicles. Therefore, according to a fourth aspect of the invention, a coolant is provided for cooling components of an electric vehicle by direct immersion cooling, comprising a partially fluorinated ether having the structure of (compound (1)).

[0025]

[0026] R1, R2, R3, and R4 are independently selected from the group consisting of H, F, Cl, Br, I, CF3, alkyl, fluoroalkyl, and haloalkyl, and R5 is independently selected from the group consisting of CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl, and perfluorohaloalkyl.

[0027] The elements of the first and second states of the present invention should be regarded as the fourth state of the present invention in practice.

[0028] Unless otherwise stated, it should be understood that the term "electric vehicle" as used herein refers to both pure electric vehicles and vehicles that use electricity as one of several propulsion methods, such as hybrid vehicles.

[0029] Preferred examples of components for electric vehicles include battery packs, electrical conductors (including any components of the charging / discharging system), and motors / transmissions. Other examples of components for electric vehicles include power electronic devices plus components of any (external) charging system, such as external power regulators and charging cables.

[0030] It has been found that the composition of the fourth state of the present invention is advantageous in that it provides a highly efficient non-conductive heat transfer fluid, wherein the composition is an azeotropic or near-azeotropic mixture.

[0031] Therefore, the composition of the fourth aspect of the present invention is preferably used as a "two-phase" system. This means (in the context of the present invention) that the coolant is allowed to boil (as appropriate via external cooling components, such as radiators) before being redirected back to the cooled components. (In environments with high ambient temperatures (such as above 40°C), a compressor may be required). Therefore, the advantage of the composition of the fourth aspect of the present invention is that this fixed boiling point provides a fixed upper limit to the operating temperature of the components of the cooled electric vehicle.

[0032] It has been found that the composition of the fourth aspect of the present invention is particularly advantageous because it helps to maximize the charging and discharging of the battery pack components of the electric vehicle and the long-term battery pack performance.

[0033] It also allows high power to be transmitted through powertrain components (such as motors and gearboxes).

[0034] By operating the electric vehicle battery pack at the optimal temperature, problems with lithium plating (observed at low temperatures) and SEI layer formation (observed at high temperatures) have been reduced.

[0035] Depending on the circumstances, the heat transferred by the composition of the fourth aspect of the present invention can be used for space heating, such as heating the interior of an electric vehicle. Furthermore and / or conversely, heat can be transferred from another source (i.e., providing a heating mode) by the composition of the fourth aspect of the present invention. This ensures that the temperature of the battery pack (or other components used in an electric vehicle) is not allowed to fall below its optimal temperature range, such as under colder conditions. This can be achieved by recovering heat from another source, electric heating, or via a heat pump.

[0036] Another preferred example of an electrical / electronic component includes computer hardware components. Therefore, according to a fifth aspect of the invention, a coolant is provided for cooling computer hardware components by direct immersion cooling, comprising a partially fluorinated ether having the structure of (compound (1)).

[0036]

[0037] R1, R2, R3, and R4 are independently selected from the group consisting of H, F, Cl, Br, I, CF3, alkyl, fluoroalkyl, and haloalkyl, and R5 is independently selected from the group consisting of CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl, and perfluorohaloalkyl.

[0038] The elements of the first and second states of the present invention should be regarded as the fifth state of the present invention in practice.

[0039] A preferred example of computer hardware components includes servers in a data center.

[0040] It has been found that the composition of the fifth state sample of the present invention is advantageous because it provides a highly efficient non-conductive heat transfer fluid, wherein the composition is an azeotropic or near-azeotropic mixture.

[0041] The composition of the fifth aspect of the present invention can be used both as a single-phase coolant (wherein the coolant does not vaporize during heat transfer) and advantageously as a "two-phase" system. This means (in the context of the present invention) that the coolant is allowed to boil (as appropriate via external cooling components, such as heat sinks) before being redirected back to the cooled components. Therefore, the advantage of the composition of the fifth aspect of the present invention is that this fixed boiling point provides a fixed upper limit to the operating temperature of the cooled computer hardware components.

[0042] It has been found that the composition of the fifth aspect of the present invention is particularly advantageous because it helps to cool computer hardware components. This eliminates the serious drawbacks previously observed with air-cooled computer hardware, including restrictive building designs and the need for expensive and inefficient air conditioning systems. Eliminating such inefficient air conditioning systems (and their noisy cooling fans) means eliminating noise problems caused by fan operation.

[0043] Furthermore, since the composition of the fifth state sample of the present invention allows for enhanced cooling efficiency, this has a chain effect of increasing the power density of computing devices; this is beneficial for reducing space requirements.

[0044] Preferably, the compositions of the third, fourth and fifth states are substantially anhydrous. The term "anhydrous" means that the composition is completely free of water or has a low water content of less than about 1000 ppm, more preferably less than 500 ppm, more preferably less than 300 ppm, more preferably less than 200 ppm and most preferably less than 100 ppm.

[0045] The components of the third, fourth, and fifth states may contain a desiccant. Alternatively, the element used with the components may have a desiccant incorporated therein or adapted to work in conjunction with it. For example, the element may be configured or formulated to incorporate a replaceable, as appropriate, desiccant-containing cartridge. [Simplified Explanation of the Diagram]

[0046] Figure 1 shows the vapor pressure curves of Novec 7100, Novec 7200, ether A and ether B.

[0047] Figure 2 shows the viscosity of Novec 7100, Novec 7200, ether A and ether B.

[0048] Figure 3 illustrates the liquid heat capacity of Novec 7100, Novec 7200, ether A and ether B.

Implementation Method

[0049] Experimental Section

[0050] The physical properties of 1,1,1,3-tetrafluoro-2-methoxypropane ("ether A"), 1,1,1,3,3-pentafluoro-2-methoxypropane ("ether B"), C4F9OCH3 (Novec 7100) and C4F9OC2H5 (Novec 7200) were determined by a series of experiments.

[0051] Experiment 1: Determination of vapor pressure

[0052] The liquid to be measured is stored in a cylindrical test cell, and its vapor pressure is measured. During measurement, the liquid is stirred using a magnetic stirrer to quickly adjust the phase equilibrium in the test cell. The temperature of the test cell is adjusted in a constant temperature bath. The temperature in the test cell is measured using a calibrated resistance thermometer (maximum error 0.05K).

[0053] For pressure measurements, a pressure transmitter from Keller (Series 35 X HTC 30 bar absolute value, error < ±0.5% full-scale error 0.15 bar) was connected to the test cell. The Keller sensor has a temperature compensation of up to 300°C. 150 ml of test liquid was filled into the test cell and degassed by vacuum. The vapor pressure of each fluid was recorded in the range of 0-120°C. This data was then used to determine the normal (atmospheric) boiling point of each fluid. The normal boiling points (in °C) found were:

[0053]

[0054] The experimental vapor pressure is shown in Figure 1.

[0055] The vapor pressure curve of Novec 7100 was found to intersect with the vapor pressure curves of ether A and ether B, indicating that the binary mixture of these ethers and Novec 7100 will form an azeotropic composition.

[0056] Experiment 2: Determination of Liquid Viscosity

[0057] Dynamic viscosity is measured using a Cambridge Viscosity Flow Viscometer under static conditions. The measurement procedure is described in detail in ASTM D 7483-13a1. The viscometer is calibrated with a calibration fluid traceable to a national viscosity standard (either DKD or NIST). The maximum deviation at the measurement temperature is 0.15 K. The maximum deviation of viscosity is 1% of the full range or 5% of the maximum measured value, whichever is lower.

[0058] The results for the four fluids are shown in Figure 2. Clearly, the viscosities of ether A and ether B are both lower than those of Novec 7100 or Novec 7200.

[0059] Experiment 3: Determination of the heat capacity of liquids

[0060] Specific heat capacity was measured using a Setaram differential scanning calorimeter μDSC VII. During this procedure, the heat applied to the reference and sample was measured within a defined temperature range. The sample was placed in a container and heated at a rate of 0.2 K / min in 5 K increments. At each 5 K temperature level, the temperature was held constant for half an hour to reach thermal equilibrium. A second empty container was heated in parallel using the same procedure in the DSC to compensate for the thermal effects of the container itself. The difference in thermal absorption behavior between the two empty containers was measured every 5 K using the same procedure and automatically subtracted. After the measurement and calibration operation, the specific heat capacity was calculated with variations in temperature, measured heat, and sample weight. The measurement results were checked using a fluid with a well-known specific heat capacity. The uncertainty of the specific heat capacity measurement was less than 3%. The results are shown in Figure 3.

[0061] It is obvious that the heat capacity of both ether A and ether B is significantly higher than that of Novec 7100 or Novec 7200.

[0062] Experiment 4: Determination of Liquid Density

[0063] The liquid densities of each of ether A, ether B, Novec 7100, and Novec 7200 were measured at room temperature using a calibrated graduated cylinder and a microbalance. The densities were found to be (in kg / m³):

[0063]

[0064] The above combination of properties indicates that both ether A and ether B require coolants with lower mass and volumetric flow rates to remove a constant amount of heat from self-heating electronic components or battery packs. This also means that if these fluids are used as coolants for single-phase pumping, the pressure drop through the cooling circuit will be lower, thereby reducing the pumping power requirements compared to Novec fluid. Therefore, when the resulting liquid is used as a single-phase coolant, combining ether A with Novec fluid will improve its heat removal capacity.

[0065] Example 6: Estimation of the formation of azeotropic mixtures

[0066] The vapor pressure data measured in Experiment 1 were used to construct a thermodynamic model based on the Peng-Robinson equation of state to estimate the behavior of binary mixtures of ether A and ether B with Novec fluid. The required critical point parameters were estimated using the Joback method described in the reference text "The Properties of Gases and Liquids, 5th edition, BE Poling, JM Prausnitz, JP O'Connell (pub. McGraw-Hill 2000)". The Mathias Copeman temperature function, as described in Mathias PM, Copeman TW, "Extension of the Peng-Robinson Equation of State to Complex Mixtures: Evaluation of the Various Forms of the Local Composition Concept", Fluid Phase Equilib., 13, 91-108, 1983, was used to ensure that the model accurately represents the vapor pressure of each fluid within the range of available experimental data.

[0067] Using this model, it was confirmed that Novec 7100 forms a binary lowest boiling point azeotrope with ether A and ether B in the temperature range of 20-100°C, which is consistent with the typical operating temperature range of submerged coolants.

Claims

1. Use of a coolant for cooling electrical / electronic components by direct immersion cooling, wherein the coolant comprises a partially fluorinated ether having the structure of compound (1), 1. Among them: R1 is CF3, R2 is H, R3 and R4 are independently selected from the group containing H, F, CF3, and fluoroalkyl, and R5 is independently selected from the group CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl, and perfluorohaloalkyl.

2. The use as described in claim 1, wherein the coolant is water-free.

3. The use as described in claim 1, wherein the coolant further comprises C4F9OCH3.

4. The use as described in claim 1, wherein the coolant further comprises some or all of a non-flammable fluorinated ketone.

5. The use as described in claim 3, wherein the coolant contains 1 to 99 wt% of non-flammable partial or complete fluorinated ketone.

6. The use as described in claim 5, which forms an azeotropic or near-azeotropic mixture.

7. For the purpose described in claim 3, forming an azeotropic or near-azeotropic mixture comprising 10 to 90 wt% C4F9OCH3 and 10 to 90 wt% 1,1,1,3-tetrafluoro-2-methoxypropane ("ether A").

8. For the purpose described in claim 3, forming an azeotropic or near-azeotropic mixture comprising 5 to 70 wt% C4F9OCH3 and 30 to 95 wt% 1,1,1,3,3-pentafluoro-2-methoxypropane (“Ether B”).

9. Use of a coolant for cooling high-voltage electrical transmission components by direct immersion cooling, wherein, The coolant contains a partially fluorinated ether having the structure of compound (1).

9. Wherein: R1 is CF3, R2 is H, R3 and R4 are independently selected from the group containing H, F, CF3 and fluoroalkyl, and R5 is independently selected from the group CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl and perfluorohaloalkyl.

10. The use as described in claim 9, wherein the coolant is water-free.

11. The use as described in claim 9, wherein the high-voltage transmission element comprises an MV / HV transformer, a circuit breaker, or a switching device.

12. The use as described in claim 9, wherein the coolant further comprises C4F9OCH3.

13. The use as described in claim 9, wherein the coolant further comprises some or all of a non-flammable fluorinated ketone.

14. The use as described in claim 12, wherein the coolant comprises 1 to 99 wt% of non-flammable partial or complete fluorinated ketone.

15. The use as described in claim 14, which forms an azeotropic or near-azeotropic mixture.

16. For the purpose described in claim 15, forming an azeotropic or near-azeotropic mixture comprising 10 to 90 wt% C4F9OCH3 and 10 to 90 wt% 1,1,1,3-tetrafluoro-2-methoxypropane ("ether A").

17. For the purpose described in claim 15, forming an azeotropic or near-azeotropic mixture comprising 5 to 70 wt% C4F9OCH3 and 30 to 95 wt% 1,1,1,3,3-pentafluoro-2-methoxypropane (“ether B”).

18. Use of a coolant for cooling electric vehicle components by direct immersion cooling, wherein, The coolant contains a partially fluorinated ether having the structure of compound (1).

18. Wherein: R1 is CF3, R2 is H, R3 and R4 are independently selected from the group containing H, F, CF3 and fluoroalkyl, and R5 is independently selected from the group CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl and perfluorohaloalkyl.

19. The use as described in claim 18, wherein the coolant is water-free.

20. The use as described in claim 18, wherein the electric vehicle component includes a battery pack, electrical conductors including components of any charging / discharging system, a motor, and / or a gearbox.

21. The use as described in claim 18, wherein the coolant further comprises C4F9OCH3.

22. The use as described in claim 18, wherein the coolant further comprises some or all of a non-flammable fluorinated ketone.

23. The use as described in claim 21, wherein the coolant comprises 1 to 99 wt% of non-flammable partial or complete fluorinated ketone.

24. The use as described in claim 21, which forms an azeotropic or near-azeotropic mixture.

25. For the purpose described in claim 24, forming an azeotropic or near-azeotropic mixture comprising 10 to 90 wt% C4F9OCH3 and 10 to 90 wt% 1,1,1,3-tetrafluoro-2-methoxypropane (“ether A”).

26. For the purpose described in claim 24, forming an azeotropic or near-azeotropic mixture comprising 5 to 70 wt% C4F9OCH3 and 30 to 95 wt% 1,1,1,3,3-pentafluoro-2-methoxypropane (“Ether B”).

27. Use of a coolant for cooling computer hardware components by direct immersion cooling, wherein, The coolant contains a partially fluorinated ether having the structure of compound (1).

27. Wherein: R1 is CF3, R2 is H, R3 and R4 are independently selected from the group containing H, F, CF3 and fluoroalkyl, and R5 is independently selected from the group CF3, alkyl, fluoroalkyl, perfluoroalkyl, haloalkyl and perfluorohaloalkyl.

28. The use as described in claim 27, wherein the coolant is water-free.

29. The use as described in claim 27, wherein the computer hardware includes a server at a data center.

30. The use as described in claim 27, wherein the coolant further comprises C4F9OCH3.

31. The use as described in claim 27, wherein the coolant further comprises some or all of a non-flammable fluorinated ketone.

32. The use as described in claim 30, wherein the coolant comprises 1 to 99 wt% of non-flammable partial or complete fluorinated ketone.

33. The use as described in claim 32, which forms an azeotropic or near-azeotropic mixture.

34. The use as described in claim 33, forming an azeotropic or near-azeotropic mixture comprising 10 to 90 wt% C4F9OCH3 and 10 to 90 wt% 1,1,1,3-tetrafluoro-2-methoxypropane ("ether A").

35. For the purpose described in claim 33, forming an azeotropic or near-azeotropic mixture comprising 5 to 70 wt% C4F9OCH3 and 30 to 95 wt% 1,1,1,3,3-pentafluoro-2-methoxypropane (“Ether B”).

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