JP2013028792A - Heat transport fluid and heat transport device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transport fluid which may improve thermal conductivity by bringing disperse substances to be dispersed in the fluid into an excellent dispersion state from the point of view of heat transfer, and to provide a heat transport device.SOLUTION: The heat transport fluid 1 includes a solvent 2 comprising water or organic substances, and a plurality of microparticles 3 to be dispersed in the solvent 2. The microparticle 3 is a sheet-shaped substance.

Description

  The present invention relates to a heat transport fluid having a specific dispersed substance dispersed in a solvent, and a heat transport device using the fluid.

  Conventionally, for example, in order to improve the heat transfer efficiency of a heat transport fluid filled in a heat exchanger, carbon nanotubes having high heat conductivity are stably dispersed in a base liquid such as water or ethylene glycol. Technology has been proposed.

  For example, the technique described in Patent Document 1 uses a cellulose derivative as a dispersant by adding a carbon nanotube and a cellulose derivative or a sodium salt thereof to the base liquid to form a heat transport fluid. The carbon nanotubes can be stably dispersed therein, and the thermal conductivity can be improved without significantly increasing the kinematic viscosity.

  In addition, the technique described in Patent Document 2 includes adding a carbon nanotube and a carboxymethyl cellulose sodium salt having an average molecular weight of 6000 to 30000 as measured by GPC to the base liquid to constitute the heat transport fluid, thereby obtaining the average molecular weight. Can be stably dispersed in the base liquid using carboxymethylcellulose sodium salt having a 6000-30000 as a dispersant, and can improve the thermal conductivity without a significant increase in kinematic viscosity It can be done.

  In addition, Patent Document 3 and Patent Document 4 are known as conventional techniques for improving the thermal conductivity of a heat transport fluid by stably dispersing carbon nanotubes.

JP 2007-31520 A JP 2008-189901 A JP 2006-291002 A JP 2008-201834 A

  The carbon nanotubes dispersed in the base liquid are not limited to the heat transport fluid described in each of the above patent documents, and exhibit a rod-like shape or a wire-like shape. When a heat transport fluid in which a dispersed material having a shape such as a carbon nanotube is dispersed is circulated through a flow path such as a heat exchanger, the long axis of the dispersed material is easily oriented in a posture along the flow direction of the heat transport fluid. Become. That is, the dispersed material is dispersed in the base liquid in such a posture that its axis and the velocity vector of the heat transport fluid are in the same direction. When many dispersed substances in the fluid are dispersed in such a posture, the heat conduction performance of the carbon nanotube does not sufficiently act in the direction orthogonal to the flow direction of the heat transport fluid, and the transmission in the orthogonal direction is not performed. There is a problem that a sufficient heat effect cannot be obtained.

  Therefore, the present invention has been made in view of the above problems, and a heat transport fluid and a heat transport device that improve the heat transfer by making a dispersed material dispersed in a fluid into a good heat transfer dispersed state. The purpose is to provide.

  In order to achieve the above object, the following technical means are adopted. That is, the invention relating to the heat transport fluid according to claim 1 is configured to include a solvent made of water or an organic substance and a plurality of microparticles dispersed in the solvent, and the microparticles are in sheet form. It is characterized by.

  According to the present invention, since the microparticles have a sheet shape, a large number of microparticles are easily subjected to an action force from the solvent when flowing in the heat transport fluid, and take various postures. It will always change. For this reason, since a large number of microparticles flow in a posture that facilitates heat conduction in the heat transfer direction required for improving the heat transfer performance of the heat transport fluid, the heat transfer coefficient of the heat transport fluid can be improved. . In addition, a large number of microparticles are rotated or shaken by receiving an action force from the solvent, thereby shaking or stirring the surrounding solvent. Since the flow of the heat transport fluid is disturbed by the stirring effect of such a large number of fine particles, the heat transfer coefficient of the heat transport fluid can be improved. Therefore, it is possible to provide a heat transport fluid that improves the heat transfer by making the dispersed material dispersed in the fluid into a good heat transfer state.

  As in the invention described in claim 2, the fine particles described in claim 1 are preferably graphite particles. According to the present invention, since the graphite fine particles dispersed in the heat transport fluid are a plurality of layers of sheet-like bodies, they have high rigidity. This high rigidity exhibits a high solvent stirring ability when the heat transport fluid flows. Further, in combination with the effect of improving the thermal conductivity of the heat transport fluid associated with the high thermal conductivity of the graphite fine particles, the heat transport fluid can exhibit high heat transfer performance.

  As in the invention described in claim 3, it is preferable that the graphite fine particles described in claim 2 are surface oxidized. According to the present invention, since an oxide layer is formed on the surface of the graphite fine particles, the graphite fine particles exhibit high dispersibility in the solvent and can provide a heat transport fluid with improved heat transfer performance.

  As in the invention described in claim 4, the fine particles described in claim 1 are preferably graphene or graphene oxide. According to the present invention, a very thin sheet shape can be produced by forming microparticles mainly from graphene or graphene oxide formed with a large number of carbon-carbon bond six-membered rings and the like. According to such fine particles, since the sheet-shaped particles greatly fluctuate in the fluid, it is possible to construct a dispersion state capable of exhibiting excellent heat transfer performance in all directions. Therefore, since the dispersed material can be in a state of good heat transfer in the fluid, reliable heat transfer can be improved.

  As in the invention described in claim 5, the fine particles described in claim 1 are preferably metal oxides.

  As in the invention described in claim 6, the solvent described in any one of claims 1 to 5 is preferably a monohydric alcohol, a polyhydric alcohol, or a mixture thereof.

  As in the invention described in claim 7, the monohydric alcohol described in claim 6 is methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol or 2-methyl-2-propanol. Or a mixture thereof.

  As in the invention described in claim 8, the polyhydric alcohol described in claim 6 is preferably ethylene glycol, propylene glycol or glycerin, or a mixture thereof.

  According to this, methanol has a melting point of −97 ° C. and a boiling point of 64.7 ° C., ethanol has a melting point of −114.3 ° C. and a boiling point of 78.4 ° C., and 1-propanol has a melting point of −126. 5 ° C., boiling point 97.15 ° C., 2-propanol has a melting point of −89.5 ° C. and a boiling point of 82.4 ° C., 1-butanol has a melting point of −90 ° C. and a boiling point of 117 ° C., Since 2-butanol has a melting point of −114.7 ° C. and a boiling point of 99 ° C., and 2-methyl-2-propanol has a melting point of 25.69 ° C. and a boiling point of 82.4 ° C., the characteristics of each of these substances By utilizing this, it is possible to provide a heat transport fluid that can be expected to transport heat according to the application.

  A ninth aspect of the present invention relates to a heat transport device that transports heat using the heat transport fluid according to any one of claims 1 to 8, and a circulation circuit in which the heat transport fluid circulates; A circulation driving device that provides a driving force for forcibly circulating the heat transport fluid in the circulation circuit, and a cooling heat that absorbs heat by the heat transport fluid that circulates heat generated from the semiconductor elements included in the semiconductor device and cools the semiconductor elements. It is characterized by comprising an exchanger and a heat radiating device for releasing the heat recovered by the cooling heat exchanger to the outside.

  According to this heat transport device, as described above, heat generated from the semiconductor element is absorbed into the heat transport fluid by using the heat transport fluid whose heat transfer is improved by the dispersion state of the heat transfer material having good thermal conductivity. By discharging in this manner, the semiconductor element can be efficiently cooled to exhibit a desired function, and the life can be improved.

  A tenth aspect of the present invention relates to a heat transport device that transports heat using the heat transport fluid according to any one of the first to eighth aspects, and a circulation circuit in which the heat transport fluid circulates; A circulation drive device that provides a driving force for forcibly circulating the heat transport fluid in the circulation circuit, and cooling heat exchange that cools the engine by exchanging heat between the fluid circulating in the engine and the heat transport fluid circulating And a heat radiating device for releasing the heat recovered by the cooling heat exchanger to the outside.

  According to this heat transport device, as described above, heat generated from the engine is absorbed by the heat transport fluid using the heat transport fluid whose heat transfer is improved by the dispersion state of the heat transfer material having good heat transfer. By discharging, it is possible to efficiently cool the engine and achieve desired functions, improved fuel consumption, improved service life, and the like.

  Claim 11 is an invention relating to a heat transport device that transports heat using the heat transport fluid according to any one of claims 1 to 8, and a circulation circuit in which the heat transport fluid circulates; A circulation drive device that provides a driving force for forcibly circulating the heat transport fluid in the circulation circuit, a heating element that provides heat to the heat transport fluid that circulates in the circulation circuit, air that is blown to the area to be air-conditioned, and And a heat exchanger that heats the air by exchanging heat with the circulating heat transport fluid.

  According to this heat transport apparatus, as described above, the heat transport fluid whose heat transfer is improved by the dispersion state of the heat transfer material is absorbed, and the heat transport fluid absorbs the heat of the heating element and is air-conditioned. By discharging with respect to the air blown to the target area, it is possible to provide heated air that is efficiently heated.

  A twelfth aspect of the present invention relates to a heat transport device that transports heat using the heat transport fluid according to any one of the first to eighth aspects, and a circulation circuit in which the heat transport fluid circulates; A circulation drive device that provides a driving force for forcibly circulating the heat transport fluid in the circulation circuit, a warm-up target device provided so that the heat transport fluid circulating in the circulation circuit can be circulated, and a heat transport fluid circulating in the circulation circuit And a heating element that applies heat to the warm-up target device. When the warm-up target device needs to be warmed up, the heat transport fluid received from the heating element is circulated to the warm-up target device.

  According to this heat transport device, as described above, the heat transport fluid whose heat transfer is improved by the dispersion state of the heat transfer material is generated from the heating element when the warm-up operation is necessary. By absorbing heat into the heat transport fluid and supplying it to the warm-up target device, it is possible to efficiently warm the warm-up target device to a state in which a desired function can be exhibited quickly.

It is explanatory drawing explaining the orientation of the carbon nanotube in the conventional heat transport fluid. It is explanatory drawing explaining the flow state of a microparticle in the heat transport fluid which concerns on 1st Embodiment to which this invention is applied. It is the graph which showed the improvement degree at the time of comparing with water about the heat transfer rate of the heat transport fluid of 1st Embodiment. It is a schematic diagram which shows the structure of the element cooling device which cools a semiconductor element using the heat transport fluid of this invention. It is a schematic diagram which shows the structure of the engine cooling device which cools an engine using the heat transport fluid of this invention. It is a schematic diagram which shows the structure of the air conditioner which warms the ventilation air to a vehicle interior using the heat transport fluid of this invention. It is a schematic diagram which shows the structure of the warming-up apparatus which warms up an engine using the heat transport fluid of this invention. It is the graph which showed the result compared with the heat conductivity of the mixed solvent of water and ethylene glycol about the heat conductivity of the heat transport fluid of 2nd Embodiment to which this invention is applied. It is the graph which showed the improvement degree with respect to the heat transfer rate of the mixed solvent of water and ethylene glycol about the heat transfer rate of the heat transport fluid of 2nd Embodiment.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each mode, the other modes described above can be applied to the other parts of the configuration. In addition to combinations of parts that clearly indicate that each embodiment can be combined specifically, the embodiments may be partially combined even if they are not clearly specified, unless there is a problem with the combination. Is possible.

(First embodiment)
Hereinafter, a first embodiment of a heat transport fluid and a heat transport device according to the present invention will be described with reference to FIGS. The heat transport fluid 1 according to the present embodiment transmits and transports heat from a heat source to the outside, and is used for cooling and heating of equipment.

  FIG. 1 is an explanatory view for explaining the orientation of carbon nanotubes 103 in a conventional heat transport fluid 101. A conventional heat transport fluid 101 includes at least a solvent 102 and a plurality of carbon nanotubes 103. Further, the plurality of carbon nanotubes 103 are dispersed in the solvent 102. The carbon nanotubes 103 included in the conventional heat transport fluid 101 are easily oriented in the solvent 102 such that the major axis of the carbon nanotubes 103 is directed to the heat transport fluid 101 in the flow direction. That is, the carbon nanotubes 103 having a rod shape or a wire shape exist in a posture in which the longitudinal direction is directed in the flow direction along the inner wall surface of the flow path in the tube through which the heat transport fluid 101 flows, and are dispersed in the solvent 102. This is because the carbon nanotubes 103 are dispersed in the solvent 102 in such a posture that the axis is directed to the velocity vector of the flow in the pipe and the flow resistance is reduced according to the flow of the heat transport fluid in the flow path.

  Of the inner wall surface of the flow path through which the heat transport fluid 101 flows, a high temperature inner wall surface 104 that is located on the heat source side and that conducts heat from the heat source and a low temperature inner wall surface 105 that faces the high temperature inner wall surface 104. Is normally transferred from the high temperature inner wall surface 104 to the low temperature inner wall surface 105 using the heat transport fluid 101 as a heat transfer medium. However, in the case of the conventional heat transport fluid 101, depending on the orientation state of the carbon nanotube 103 as described above, the long axis of the carbon nanotube 103 does not face in the direction orthogonal to the flow direction, and the carbon nanotube 103 functions as a heat transfer medium. Therefore, heat is not easily transmitted from the high temperature inner wall surface 104 to the low temperature inner wall surface 105. Therefore, since the heat transport fluid 1 of the first embodiment has the characteristic microparticles 3, the microparticles 3 function as a heat transfer medium and the effect of stirring the solvent 2 can be obtained. The heat transfer property from 104 to the low temperature inner wall surface 105 can be improved.

  The solvent 2 used in the heat transport fluid 1 of the present embodiment includes a single component such as water, for example, and contains fine particles 3 having a higher thermal conductivity than the solvent 2. The solvent 2 is, for example, water or an organic substance (for example, monohydric alcohols, polyhydric alcohols, etc.). The solvent 2 can be a fluid that disperses the microparticles 3 and carries the microparticles 3. This fluid may be provided by a liquid or a gas. A fluid may be composed of single or multiple components. For example, water or a liquid polymer can be used as the fluid. Furthermore, a mixture can be used as the fluid. As the mixture, for example, water, ethylene glycol, monohydric alcohols, and a mixture of at least two of polyhydric alcohols, or a mixture of this mixture and other functional components can be used.

The monohydric alcohol used for the solvent is an alcohol having one hydroxy group (—OH), for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol or 2-methyl- 2-propanol or a mixture thereof. Methanol is represented by CH ₃ OH and has a melting point of −98 ° C. and a boiling point of 65 ° C., and ethanol is represented by CH ₃ CH ₂ OH and has a melting point of −117 ° C. and a boiling point of 79 ° C.

1-propanol and 2-propanol are monohydric alcohols having 3 carbon atoms. 1-propanol is represented by CH ₃ CH ₂ CH ₂ OH and has characteristics of a melting point of −127 ° C. and a boiling point of 97 ° C. 2-propanol is also called isopropanol and is represented by CH ₃ CH (OH) CH ₃ , and has a melting point of −90 ° C. and a boiling point of 83 ° C.

1-butanol, 2-butanol, and 2-methyl-2-propanol are monohydric alcohols having 4 carbon atoms. 1-butanol is represented by CH ₃ CH ₂ CH ₂ OH and has characteristics of a melting point of −117 ° C. and a boiling point of 90 ° C. 2-Butanol is a secondary alcohol, also called sec-butanol, represented by CH ₃ CH (OH) CH ₂ CH ₃ and having a melting point of −115 ° C. and a boiling point of 100 ° C. 2-Methyl-2-propanol is a tertiary alcohol, also called tert-butanol, represented by (CH ₃ ) ₃ COH, having a melting point of 25 ° C. and a boiling point of 83 ° C. It has the property of being less oxidized than the body.

The polyhydric alcohol used for the solvent is an alcohol having two or more hydroxy groups (—OH), such as ethylene glycol, propylene glycol or glycerin, or a mixture thereof. Ethylene glycol is a dihydric alcohol, is represented by CH ₂ (OH) CH ₂ OH, has a melting point of −13 ° C., and a boiling point of 198 ° C., and is used as a main component of a radiator antifreeze. Propylene glycol is a dihydric alcohol, represented by CH ₃ CH (OH) CH ₂ OH, has a melting point of −59 ° C. and a boiling point of 188.2 ° C., and can be used as an antifreeze. Glycerin is a trihydric alcohol, is represented by CH ₂ (OH) CH (OH) CH ₂ OH, has a melting point of 18 ° C. and a boiling point of 290 ° C., and can be used as an antifreeze.

  Each of the above alcohols having characteristics such as a suitable melting point and boiling point is used as the solvent 2 according to the use conditions of the heat transport fluid 1.

Each of the plurality of microparticles 3 is a nanometer or micrometer order size particle and is dispersed in the solvent 2 of the heat transport fluid 1. As the fine particles 3, for example, particles having an average particle diameter in the range of 1 nm to 10 μm may be used. Examples of the fine particles 3 include particles made of a metal such as gold (Au), silver (Ag), and platinum (Pt), particles made of graphene or graphene oxide, manganese dioxide (MnO ₂ ), titanium oxide (TiO ₂ ), and the like. Particles made of the metal oxide can be used. Moreover, the microparticle 3 may be comprised from two or more types of substances.

  The heat transport fluid 1 may include a coating agent having a functional group that adsorbs to the microparticles 3. By arranging the coating agent on the surface of the microparticle 3, solvent molecules are taken in between the coating agent and on the surface and the solvent molecules gather around the microparticle 3. 1 can be stably dispersed.

  The microparticles 3 used in the heat transport fluid 1 are flat sheet-shaped substances that are thin and have a large surface area compared to a cross section parallel to the thickness direction. As the sheet shape, various shapes can be employed. For example, the microparticle 3 has a flat body whose outer shape in a cross section parallel to the thickness direction is rectangular, elliptical, polygonal, or the like. . Further, the sheet shape is not limited to a flat plate shape, and may be a shape in which irregularities are formed on the surface. As a preferred example of the fine particles 3 having such a sheet shape, graphene or graphene oxide is used.

  FIG. 2 is an explanatory diagram for explaining the flow state of the microparticles 3 in the heat transport fluid 1. As schematically illustrated in FIG. 2, by dispersing the microparticles 3 having such a characteristic shape in the solvent 2, the microparticles having a sheet shape are received by receiving forces from multiple directions accompanying the flow velocity distribution of the flow in the pipe. The particles 3 flow while rotating or swinging in the heat transport fluid 1. Due to the flow of the microparticles 3, the microparticles 3 themselves can flow in a posture that facilitates heat conduction in the heat transfer direction necessary for improving the heat transfer performance (the direction indicated by the white arrow in FIG. 2). The active flow of the solvent 2 can be promoted. Therefore, the heat transport fluid 1 of the present embodiment is dispersed in the solvent 2 in an irregular and random posture instead of the carbon nanotubes included in the conventional heat transport fluid.

  In other words, since each microparticle 3 has a flat sheet shape, for example, when it flows in the pipe, it moves finely or greatly in the heat transport fluid 1 or moves in any direction. To do. Since a large number of microparticles 3 flow in this manner, the solvent 2 is shaken or swirled as compared with a conventional heat transport fluid, so that the solvent 2 is agitated and the microparticles 3 are irregularly and randomly oriented. It is thought to bring about a state. Further, the effect of stirring the solvent 2 and the active flow of the microparticles 3 themselves improve the heat transfer direction in the heat transport fluid 1, and the heat transfer effect in the direction orthogonal to the flow direction is sufficient. Is obtained.

  The production of the heat transport fluid 1 using graphene oxide as the fine particles 3 will be described. Graphite is oxidized in a solution of potassium permanganate and sulfuric acid, and this solution is centrifuged and washed. When this centrifugation and washing are repeated many times, a uniform solution is obtained, and the heat transport fluid 1 containing graphene oxide, which is a single layer of graphite, can be produced as the fine particles 3. It has been confirmed that the fine particles 3 thus produced contain graphene oxide having a thickness dimension of about 1 nm and an average particle size of about 1.5 μm.

  The inventors measured the heat transfer coefficient improvement ratio with respect to the heat transfer coefficient when water was used as the heat transfer fluid for the heat transfer coefficient of the heat transfer fluid 1 produced by the above-described manufacturing method by the laser flash method. The result is shown in FIG. FIG. 3 is a graph showing the degree of improvement (heat transfer coefficient improvement ratio) with respect to the heat transfer coefficient of the heat transport fluid 1 of the present embodiment when the heat transfer coefficient is 1 when water is used. In FIG. 3, the horizontal axis represents the volume concentration (vo1%) of the graphene oxide aqueous solution as the dispersed substance concentration, the vertical axis represents the heat transfer coefficient improvement ratio, and FIG. The corresponding heat transfer coefficient improvement ratio is plotted. The measured value is a value obtained by measuring the heat transfer coefficient in forced convection around a cylinder having a flow velocity of 4 (mm / s).

  From the measurement results shown in FIG. 3, it can be seen that the heat transfer coefficient improvement ratio increases in proportion to the volume concentration (dispersed substance concentration) of the graphene oxide aqueous solution. Thus, according to the heat transport fluid 1 by said manufacturing method, it has confirmed that a heat transfer rate improved.

(Application example of heat transport fluid according to the present invention)
The heat transport fluid according to the present invention includes, for example, an inverter cooling fluid, a fuel cell cooling fluid, a secondary battery cooling fluid, a motor cooling fluid, an electronic device element cooling fluid, a hot water supply heat medium, and a floor heating The present invention can also be applied to a heat medium, a heat medium for bathroom heating, a heat medium for solar heat recovery, a cooling fluid for an intercooler, and the like.

(First example of heat transport device)
A first example of a heat transport device using the heat transport fluid 1 will be described with reference to FIG. FIG. 4 is a schematic diagram illustrating a configuration of an element cooling apparatus that cools a semiconductor element, which is a first example of a heat transport apparatus.

  As shown in FIG. 4, the heat transport device 10 that transports heat using the heat transport fluid 1 includes a circulation circuit 11 in which the heat transport fluid circulates, and a drive that forcibly circulates the heat transport fluid in the circulation circuit 11. A pump 12 as a circulation drive device for applying force, a heat exchanger 13 for cooling which absorbs heat generated from the semiconductor elements included in the semiconductor device 14 by a heat transport fluid, and cools the semiconductor elements, and a heat exchanger for cooling And a heat exchanger 15 for radiating heat as a heat radiating device for releasing the heat recovered in 13 to the outside. The heat transport device 10 constitutes a system in which these components are connected in a ring shape by piping. Furthermore, the heat exchanger 15 for heat dissipation is provided with a blower 16 that blows air.

  The semiconductor device 14 to be cooled is, for example, an inverter device that controls various electronic devices, motors, and the like. The semiconductor element is an electric circuit element made of a semiconductor, for example, a transistor such as an IGBT element (insulated gate bipolar transistor element) constituting a switching element, a diode, or the like. The semiconductor element may be thermally connected to a heat sink or the like, and the heat sink may be in direct contact with the heat transport fluid to cool the semiconductor element, or the semiconductor element may be provided in the heat transport fluid flow path to A structure may be employed in which the semiconductor element is cooled by direct contact between the transport fluid and the semiconductor element.

  When the semiconductor element needs to be cooled, the pump 12 is driven to forcibly circulate the heat transport fluid built in the circulation circuit 11. The heat transport fluid absorbs heat indirectly or directly from the semiconductor element as it passes through the passage in the cooling heat exchanger 13, and the semiconductor element is cooled. When the heat transport fluid that has absorbed the heat of the semiconductor element next passes through the passage in the heat dissipation heat exchanger 15, the heat transport fluid exchanges heat with the air flowing so as to come into contact with the passage in the heat dissipation heat exchanger 15 by the blower 16. Then, the air is deprived of heat and dissipates heat to the outside. The heat transport fluid is further sucked into the pump 12 and continuously circulates in the circulation circuit 11, and repeats heat absorption in the heat exchanger 13 for cooling and heat dissipation in the heat exchanger 15 for heat dissipation, thereby performing continuous heat transport.

  According to the heat transport device 10, since the heat transport fluid 1 of the present embodiment is used, heat transfer can be improved by the dispersion state of the dispersed material having good heat transfer. The heat generated from the semiconductor element is absorbed by the heat transport fluid 1 and released to the outside, so that the semiconductor element can be efficiently cooled, and the desired function of the semiconductor element can be exhibited and the life can be improved. The heat transport device 10 to be realized can be provided.

(Second example of heat transport device)
A second example of a heat transport device using the heat transport fluid 1 will be described with reference to FIG. FIG. 5 is a schematic diagram showing a configuration of an engine cooling device that cools the engine, which is a second example of the heat transport device.

  As shown in FIG. 5, the heat transport device 20 that transports heat using the heat transport fluid 1 includes a circulation circuit 21 in which the heat transport fluid circulates, and a drive that forcibly circulates the heat transport fluid in the circulation circuit 21. A pump 22 as a circulation drive device that applies power, a heat exchanger 23 for cooling that absorbs heat generated from a fluid flowing inside the engine 28 with a heat transport fluid, and cools the engine 28, and a heat exchanger 23 for cooling And a heat-dissipating heat exchanger 24 as a heat-dissipating device that releases the heat recovered in step 1 to the outside. The heat transport apparatus 20 constitutes a system in which these components are connected in a ring shape by piping. Furthermore, the heat-dissipating heat exchanger 24 is provided with a blower 25 that blows air. The fluid flowing through the engine 28 circulates in a circulation circuit 26 formed by connecting the engine 28, the pump 27, and the heat radiation side passage 23 b through which the engine cooling fluid in the cooling heat exchanger 23 passes in a ring shape. To do.

  The engine 28 to be cooled is, for example, an automobile gasoline engine, diesel engine, power generation engine, agricultural engine, or the like. The fluid that circulates inside the engine 28 is, for example, engine cooling water mainly composed of water or ethylene glycol. The heat radiation side passage 23b through which the engine coolant flows and the heat absorption side passage 23a through which the heat transport fluid 1 of the present embodiment flows are arranged inside the cooling heat exchanger 23, and the respective passages are in contact with each other. A relationship or a relationship in which one passage is included inside the other passage. For example, heat exchange can be performed by one fluid flowing through the inner passage of the inner tube and the other fluid flowing through the inner passage of the outer tube through which the inner tube passes.

  When the engine 28 needs to be cooled, the pump 22 is driven to forcibly circulate the heat transport fluid 1 built in the circulation circuit 21 and the pump 27 is driven to build the engine built in the circulation circuit 26. Cooling water is forced to circulate. The heat transport fluid 1 absorbs heat from the engine cooling water when passing through the heat absorption side passage 23a in the cooling heat exchanger 23, and the engine cooling water is cooled, so that the heat of the engine 28 moves to the heat transport fluid. Then, the engine 28 is cooled.

  When the heat transport fluid 1 that has absorbed the heat of the engine 28 next passes through the passage in the heat dissipation heat exchanger 24, the air and heat flowing so as to come into contact with the passage in the heat dissipation heat exchanger 24 by the blower 25. The air is deprived of heat and dissipated to the outside. The heat transport fluid 1 is further sucked into the pump 22 and continuously circulates in the circulation circuit 21, and repeats heat absorption in the cooling heat exchanger 23 and heat dissipation in the heat dissipation heat exchanger 24 to perform continuous heat transport. .

  According to the heat transport device 20, since the heat transport fluid 1 of the present embodiment is used, heat transfer can be improved by the dispersion state of the dispersed material having a good heat transfer. The heat generated from the engine 28 is absorbed by the heat transport fluid 1 and released to the outside so that the engine can be efficiently cooled, realizing the desired functions of the engine 28, improving fuel consumption, improving service life, etc. The heat transport device 20 can be provided.

(Third example of heat transport device)
A third example of the heat transport apparatus using the heat transport fluid 1 will be described with reference to FIG. FIG. 6 is a schematic diagram illustrating a configuration of an air conditioner that is a third example of the heat transport device and that warms the air blown into the vehicle interior.

  As shown in FIG. 6, the heat transport device 30 that transports heat using the heat transport fluid 1 circulates the heat transport fluid 1 forcibly through the circulation circuit 31 and the circulation circuit 31. The pump 32 serving as a circulation drive device that supplies the driving force to be generated, the heating element 33 that supplies the heat transport fluid 1 with a heat quantity for heating, and the heat transport fluid 1 that has absorbed the heat of the heating element 33 are blown into the room. A heating heat exchanger 34 that warms the air to be heated. The heat transport device 30 constitutes a system in which these components are connected in a ring shape by piping. Furthermore, the heating heat exchanger 34 is disposed in an air conditioning case 36 that forms a passage for air to be blown into the passenger compartment, and the air is supplied to the heating heat exchanger 34 in the air conditioning case 36. A blower 35 for sending is provided. The air passage in the air conditioning case 36 is connected to an air conditioning target area such as a room. The air conditioning case 36 constitutes a part of a vehicle air conditioner that air-conditions a vehicle interior, an indoor air conditioner that air-conditions a living room, a large-scale air conditioning system that air-conditions a factory, a facility, or a specific outdoor space.

  When heating to an air-conditioning target area such as a room is required, the pump 32 is driven to forcibly circulate the heat transport fluid 1 built in the circulation circuit 31, and further, the heating heat is generated by driving the blower 35. Air blown to the air-conditioning target area passing through the exchanger 34 is generated. The heat transport fluid 1 absorbs heat generated from the heating element 33 when passing through the heating element 33, and releases the absorbed heat to the blowing air when passing through the heating heat exchanger 34, so that the blowing air is warmed. Therefore, the heat of the heat generating body 33 moves to the blown air via the heat transport fluid 1, and the heating air is supplied to the air-conditioning area. The heat transport fluid 1 is further sucked into the pump 32 and continuously circulates in the circulation circuit 31, and repeats heat absorption by the heating element 33 and heat radiation to the blown air by the heat exchanger 34 for heating, thereby continuing continuous heat transport. Do.

  According to the heat transport device 30, since the heat transport fluid 1 of the present embodiment is used, heat transfer can be improved by the dispersion state of the dispersed material having a good heat transfer. Since the heat of the heating element 33 is absorbed by the heat transport fluid 1 and efficiently moves to the air-conditioning target area, it is possible to provide heating air with excellent energy efficiency.

(Fourth example of heat transport device)
A fourth example of the heat transport device using the heat transport fluid 1 will be described with reference to FIG. FIG. 7 is a schematic diagram showing a configuration of a warm-up device that warms up the engine, which is a fourth example of the heat transport device.

  As shown in FIG. 7, the heat transport device 40 that transports heat using the heat transport fluid 1 includes a circulation circuit 41 in which the heat transport fluid circulates, a PTC heater 46 that is a heating element, and a PTC heater 46. And a bypass passage 45 to be provided. The PTC heater 46 is a heating element that applies heat to the heat transport fluid 1 flowing through the bypass passage 45. The circulation circuit 41 includes a pump 42, an engine 43, and a radiator 44, and is configured by connecting them in a ring shape by piping.

  The bypass passage 45 is a bypass passage for returning the heat transport fluid 1 that has flowed out of the engine 43 to the engine 43 via the PTC heater 46 without flowing down to the radiator 44 side. The heat transport fluid 1 that has flowed out of the engine 43 is selected to flow down to the PTC heater 46 or to the radiator 44 by the passage switching by the three-way valve 47. The pump 42 is a circulation drive device that provides a driving force for forcibly circulating the heat transport fluid 1 in the circulation circuit 41. The engine 43 is a warm-up target device that is provided with the heat transport fluid 1 that circulates in the circulation circuit 41 so that it can circulate and that requires warm-up. The radiator 44 is a heat radiating heat exchanger for cooling the heat transport fluid 1 by releasing the heat recovered by the engine 43 to the outside. In addition, the radiator 44 is provided with a blower that blows air.

  The engine 43 that is a cooling target and a warm-up target is, for example, an automobile gasoline engine, a diesel engine, a power generation engine, an agricultural engine, or the like. That is, the heat transport fluid 1 has a function as cooling water for cooling the engine and a function for warming up in order to efficiently exhibit the performance of the engine.

  In a state where the engine 43 needs to be cooled, the heat transport fluid 1 incorporated in the circulation circuit 41 is forcedly circulated by driving the pump 42, and the three-way valve 47 and the outlet side passage of the engine 43 and the inlet side of the radiator 44 are circulated. The passage is connected. At this time, since the heat transport fluid 1 circulates in the circulation circuit 41 and passes through the radiator 44, heat is taken away by the external air and dissipated and cooled, so that the heat of the engine 43 moves to the external air, The engine 43 is cooled.

  In a state where the engine 43 needs to be warmed up, for example, when the temperature of the heat transport fluid 1 is equal to or lower than a predetermined temperature, the heat transport fluid 1 built in the circulation circuit 41 is forcibly circulated by driving the pump 42. In addition, the outlet side passage of the engine 43 and the bypass passage 45 are connected by the three-way valve 47. At this time, the heat transport fluid 1 is heated by the PTC heater 46 when it circulates through the circulation circuit 41 and passes through the bypass passage 45, so that the engine 43 is warmed by the returned heat transport fluid 1. Note that the three-way valve 47 may be configured by a thermostat that is set so as to switch the passage to be connected depending on the detected temperature.

  According to the heat transport device 40, since the heat transport fluid 1 of the present embodiment is used, heat transfer can be improved by the dispersion state of the dispersed material having a good heat transfer. The engine 43 can be efficiently heated via the heat transport fluid 1 heated by the heating element, and the heat transport device 40 that realizes the desired function of the engine 43, improved fuel consumption, improved service life, and the like can be provided.

  The effects brought about by the heat transport fluid 1 according to this embodiment will be described below. The heat transport fluid 1 includes a solvent 2 made of water or an organic substance, and a plurality of microparticles 3 dispersed in the solvent 2, and the microparticles 3 are sheet-shaped substances.

  According to the heat transport fluid 1, the microparticles 3 have a sheet shape. Therefore, when the microparticles 3 flow in the heat transport fluid 1, the microparticles 3 are easily subjected to an action force from the solvent 2 and have various postures. The posture is always changing. For this reason, many microparticles 3 flow in a posture that facilitates heat conduction in a heat transfer direction (direction perpendicular to the main flow direction of the fluid) necessary for improving the heat transfer performance of the heat transport fluid 1. The heat transfer coefficient of the heat transport fluid 1 can be improved. In addition, a large number of microparticles 3 are rotated or shaken by receiving an acting force from the solvent 2, thereby shaking or stirring the surrounding solvent 2. Since the flow of the heat transport fluid 1 is disturbed by the stirring effect of such a large number of microparticles 3, the heat transfer coefficient of the heat transport fluid 1 can be improved.

  The fine particles 3 are preferably graphene or graphene oxide. According to this, since graphene or graphene oxide is a sheet of sp2 bonded carbon atoms having a thickness of 1 atom (a sheet formed mainly having a number of carbon-carbon bonded six-membered rings), A very thin sheet-shaped microparticle 3 can be produced. According to such fine particles 3, since the sheet-like particles greatly fluctuate in the fluid, it is possible to construct a dispersed state that can exhibit excellent heat transfer performance in all directions. Therefore, since the dispersed substance can be in a heat dispersion state excellent in the fluid, more reliable heat transfer can be achieved.

  Moreover, it is preferable that the microparticle 3 is a metal oxide. The solvent 2 is preferably a monohydric alcohol or a polyhydric alcohol, or a mixture thereof.

  Further, the monohydric alcohol is preferably methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol or 2-methyl-2-propanol, or a mixture thereof.

  Furthermore, the polyhydric alcohol is preferably ethylene glycol, propylene glycol or glycerin, or a mixture thereof. According to this, the heat transport fluid which can anticipate the improvement of the heat transport according to a use can be provided by aiming at the use which utilized the characteristics (melting point, boiling point, etc.) of each of these substances.

(Second Embodiment)
A second embodiment of the heat transport fluid according to the present invention will be described with reference to FIGS. In the following, in the second embodiment, configurations and operational effects different from those in the first embodiment will be described, and configurations and operational effects not described will be the same as those in the first embodiment. Needless to say, the first to fourth heat transport devices described above are devices that perform heat transport using the heat transport fluid of the second embodiment.

  The heat transport fluid 1 according to the second embodiment is characterized in that the fine particles 3 are graphite fine particles. The production of the heat transport fluid 1 using graphite fine particles as the fine particles 3 will be described.

  First, graphite particles are put into a mixed solution of sulfuric acid and nitric acid to generate expandable graphite fragments. The generated expandable graphite fragments are heat-treated in air up to 900 ° C. Furthermore, the graphite fragments are further finely crushed by performing at least one of crushing techniques such as ultrasonic treatment, ball mill crushing, and vibration ball mill crushing on the heat-treated expandable graphite pieces. Through these steps, fine graphite particles are obtained. This technique for producing graphite fine particles is known in a published document (Macromolecular Materials and Engineering 2005, 290, 179-187). The fine graphite particles thus obtained are dispersed in a solvent together with a dispersant. The heat transport fluid of the second embodiment is prepared using sodium benzenesulfonate as a dispersant. By the above method, the heat transport fluid 1 in which the graphite fine particles are dispersed in the solvent as the sheet-like fine particles 3 can be produced.

  Furthermore, it is preferable to subject the graphite fine particles to surface oxidation. That is, an oxide layer is formed on the surface of the graphite fine particles by various oxidation methods, so that the dispersibility of the graphite fine particles in the solvent 2 is increased, which contributes to the improvement of the thermal conductivity of the heat transport fluid 1.

  This surface oxidation can be carried out by oxidizing the graphite fine particles produced by the above-described method by ozone oxidation, oxidation treatment using an oxidizing agent, or the like. In ozone oxidation, graphite fine particles are exposed to a mixed gas of ozone and oxygen produced by an ozone generator to cause an oxidation reaction. The surface layer oxidation technique by this ozone oxidation is known in a published document (Carbon 49 (2011), 3242-3249).

  The inventors measured the thermal conductivity of the heat transport fluid 1 produced by the manufacturing method described in the second embodiment, and the volume concentration of the microparticles 3 is 3.0 vol%, 1.0 vol%, and 0.25 vol%, respectively. In the case of a solution and a mixed solvent of water and ethylene glycol (mixing ratio is 1: 1), measurement was performed by a hot wire method (also referred to as unsteady hot wire method). The result is shown in FIG. FIG. 8 is a bar graph showing the thermal conductivity measured for each solution.

  From the measurement results shown in FIG. 8, the thermal conductivity of the solution in which the graphite fine particles are dispersed as the fine particles 3 is larger than the thermal conductivity of the mixed solvent, and becomes larger as the volume concentration of the graphite fine particles becomes higher. It was confirmed that the heat conduction performance of the transport fluid 1 was improved.

  Furthermore, the inventors set the heat transfer coefficient improvement ratio with respect to the heat transfer coefficient when the above mixed solvent (the mixing ratio of water and ethylene glycol is 1: 1) for the heat transfer coefficient of the heat transport fluid 1 to the heat ray. Measured by the method. The result is shown in FIG. FIG. 9 is a bar graph showing the heat transfer coefficient measured for each solution. The measured value is a value obtained by measuring the heat transfer coefficient in forced convection around a cylinder having a flow velocity of 4 (mm / s).

  From the measurement results shown in FIG. 9, it can be seen that the heat transfer coefficient improvement ratio increases almost in proportion to the volume concentration (dispersed substance concentration) of the graphite fine particles. Thus, according to the heat transport fluid 1 by the said manufacturing method of 2nd Embodiment, it has confirmed that a heat transfer rate improved.

  Further, the graphite fine particles dispersed in the heat transport fluid 1 are sheet-like fine particles that form a plurality of layers in appearance, and have higher rigidity and higher thermal conductivity than the fine particles 3 made of graphene or graphene oxide. doing. That is, the graphite fine particles dispersed in the heat transport fluid 1 are the fine particles 3 forming a multilayered sheet, and are a multilayered sheet-like body, and therefore have higher rigidity than the single-layered sheet-like body. Due to this high rigidity, the graphite fine particles have a high function of shaking or stirring the solvent 2 when the heat transport fluid 1 flows, and exhibit a high effect of stirring the solvent 2. Furthermore, the graphite fine particles can effectively improve the thermal conductivity as a dispersion due to the high thermal conductivity of the microparticles themselves. Therefore, this characteristic of the graphite fine particles brings about the improvement of the heat transfer performance of the heat transport device confirmed by the measurement result.

  In addition, since graphite fine particles are more hydrophobic than graphene oxide and metal oxides, a dispersant is necessary to ensure dispersibility in a solvent. According to the surface oxidation treatment of graphite fine particles, a dispersant is used. Unnecessary dispersibility can be obtained.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. The structure of the said embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to the range of these description. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The equipment warmed up in the fourth heat transport device can be applied to, for example, an inverter device, a fuel cell, a secondary battery, an electric motor and the like in addition to the engine.

  Moreover, you may use what consists of two types of components as a solvent contained in the heat transport fluid 1. FIG. Of these, one kind of solvent may be a liquid having a freezing point depressing action. For example, water can be used as the solvent, and potassium acetate, sodium acetate, or the like can be used as the freezing point depressant. According to such a structure, the practicality in a cold region etc. can further be improved by lowering the freezing point of the heat transport fluid. Furthermore, if necessary, in addition to the freezing point depressant, a rust inhibitor or an antioxidant may be added to the heat transport fluid as an additive. If there is no need to lower the freezing point of the heat transport fluid, two or more kinds of solvents that do not contain a freezing point depressant may be used.

DESCRIPTION OF SYMBOLS 1 ... Heat transport fluid 2 ... Solvent 3 ... Fine particle 10, 20, 30, 40 ... Heat transport device 11, 21, 31, 41 ... Circulation circuit 12, 22, 32, 42 ... Pump (ring drive device)
13, 23 ... Heat exchanger for cooling 14 ... Semiconductor device 15, 24 ... Heat exchanger for heat radiation (heat radiation device)
28 ... Engine 33 ... Heating element 34 ... Heat exchanger for heating (heat exchanger)
43 ... Engine (equipment subject to warm-up)
46 ... PTC heater (heating element)
104 ... High temperature inner wall surface 105 ... Low temperature inner wall surface

Claims (12)

A solvent consisting of water or organic matter,
A plurality of microparticles dispersed in the solvent;
Comprising
The heat transport fluid according to claim 1, wherein the fine particles have a sheet shape.   The heat transport fluid according to claim 1, wherein the fine particles are fine graphite particles.   The heat transport fluid according to claim 2, wherein the graphite fine particles are surface-oxidized.   The heat transport fluid according to claim 1, wherein the fine particles are graphene or graphene oxide.   The heat transport fluid according to claim 1, wherein the fine particles are a metal oxide.   The heat transport fluid according to any one of claims 1 to 5, wherein the solvent is a monohydric alcohol, a polyhydric alcohol, or a mixture thereof.   The monohydric alcohol is methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol or 2-methyl-2-propanol, or a mixture thereof. The heat transport fluid as described.   The heat transport fluid according to claim 6, wherein the polyhydric alcohol is ethylene glycol, propylene glycol, glycerin, or a mixture thereof. A heat transport device for transporting heat using the heat transport fluid according to any one of claims 1 to 8,
A circulation circuit through which the heat transport fluid circulates;
A circulation driving device for providing a driving force for forcibly circulating the heat transport fluid in the circulation circuit;
A cooling heat exchanger that cools the semiconductor element by absorbing heat generated from the semiconductor element included in the semiconductor device with the circulating heat transport fluid;
A heat radiating device for releasing the heat recovered by the heat exchanger for cooling to the outside;
A heat transport device comprising: A heat transport device for transporting heat using the heat transport fluid according to any one of claims 1 to 8,
A circulation circuit through which the heat transport fluid circulates;
A circulation driving device for providing a driving force for forcibly circulating the heat transport fluid in the circulation circuit;
A heat exchanger for cooling that cools the engine by exchanging heat between the fluid flowing through the engine and the circulating heat transport fluid;
A heat radiating device for releasing the heat recovered by the heat exchanger for cooling to the outside;
A heat transport device comprising: A heat transport device for transporting heat using the heat transport fluid according to any one of claims 1 to 8,
A circulation circuit through which the heat transport fluid circulates;
A circulation driving device for providing a driving force for forcibly circulating the heat transport fluid in the circulation circuit;
A heating element for applying heat to the heat transport fluid circulating in the circulation circuit;
A heat exchanger that heats the air by exchanging heat between the air blown to the area to be air-conditioned and the circulating heat transport fluid;
A heat transport device comprising: A heat transport device for transporting heat using the heat transport fluid according to any one of claims 1 to 8,
A circulation circuit through which the heat transport fluid circulates;
A circulation driving device for providing a driving force for forcibly circulating the heat transport fluid in the circulation circuit;
A warm-up target device provided such that a heat transport fluid circulating in the circulation circuit can be circulated;
A heating element for applying heat to the heat transport fluid circulating in the circulation circuit;
With
When the warm-up target device needs to be warmed up, the heat transport device that circulates the heat transport fluid received from the heating element to the warm-up target device.

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