Preparation method of nanofluid

Abstract

The embodiment of the invention relates to the technical field of nanofluid preparation, in particular to a nanofluid preparation method which is used for mixing metal nanoparticles and alkali metal to form nanofluid and comprises the steps that S1, the metal nanoparticles are coated with solid alkali metal so as to form an integrated piece with the solid alkali metal; s2, adding the integrated piece into liquid alkali metal; and S3, uniformly mixing the integrated piece with liquid alkali metal to form the nanofluid. According to the embodiment of the invention, the nanoparticles are coated with the solid alkali metal to form the integrated piece, and then the integrated piece is added into the liquid alkali metal, so that the metal nanoparticles can be prevented from being adsorbed on the inner wall of a container or a pipeline, and the situation that the ratio of the metal nanoparticles to the alkali metal is not accurate can be avoided.

Description

Technical Field

[0001] The present application relates to the technical field of nanofluid preparation, and in particular to a method for preparing a nanofluid. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] Compared with previous nuclear energy systems, the fourth-generation nuclear energy system is required to show higher reliability, higher safety and higher economy. Among them, the sodium-cooled fast reactor, one of the fourth-generation nuclear energy systems, mainly uses liquid metallic sodium as a coolant. Although metallic sodium has excellent heat transfer performance, neutron economy and material compatibility as a coolant, the chemical activity of metallic sodium is relatively high, which also brings constraints to the development of sodium-cooled fast reactors. For example, if there is a breach in the cooling main pipeline or the heat exchanger breaks, when the leaked metallic sodium contacts the oxygen or water in the environment, a violent sodium fire or sodium-water reaction will occur, thereby releasing a large amount of heat.

[0004] In order to mitigate the above-mentioned reactive accidents, sodium-based nanofluids with better heat transfer performance and lower chemical activity can be used to replace traditional metallic sodium coolants. However, the preparation effect of sodium-based nanofluids is not ideal at present. Summary of the invention

[0005] A brief overview of the present application is provided below in order to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify the key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0006] The inventors of the present application have found that the prepared nanofluid has an inaccurate ratio problem. The inventors of the present application have further found that this is because the nanoparticles have a large specific surface area. When the nanoparticles are sent to a container to mix with the solid alkali metal, the nanoparticles will be adsorbed on the inner wall of the container or pipeline in contact with them, so that the nanoparticles actually mixed with the liquid alkali metal cannot meet the ratio requirements.

[0007] In view of the above technical problems, an embodiment of the present application provides a method for preparing a nanofluid, which is used to mix metal nanoparticles with alkali metals to form a nanofluid, and the method comprises:

[0008] S1, coating the metal nanoparticles with a solid alkali metal to form an integral piece with the solid alkali metal;

[0009] S2, adding the integral part into liquid alkali metal;

[0010] S3, uniformly mixing the integral member with liquid alkali metal to form a nanofluid.

[0011] In the embodiment of the present application, nanoparticles are coated with solid alkali metal to form an integral part, and then the integral part is added into liquid alkali metal. This can prevent the metal nanoparticles from being adsorbed on the inner wall of the container or pipeline, thereby helping to avoid an inaccurate ratio of the metal nanoparticles and the alkali metal.

[0012] These and other advantages of the present application will become more apparent through the following detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to further illustrate the above and other advantages and features of the present application, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings together with the following detailed description are included in this specification and form a part of this specification. Elements with the same function and structure are represented by the same reference numerals. It should be understood that these drawings only describe typical examples of the present application and should not be regarded as limiting the scope of the present application.

[0014] Figure 1 Schematic diagram of the structure of a nanofluid preparation system according to an embodiment of the present application.

[0015] Figure 2 yes Figure 1 A partial enlarged schematic diagram of the mixing container of the preparation system is shown.

[0016] Figure 3 is a schematic flow chart of a method for preparing a nanofluid according to an embodiment of the present application.

[0017] It should be noted that the drawings are not necessarily drawn to scale, but are merely shown in a schematic manner that does not affect the reader's understanding.

[0018] Description of reference numerals:

[0019] 11. mixing container; 111. mixing chamber; 112. mixing body; 113. mixing cover; 114. stirring through hole;

[0020] 121, first feed pipeline; 122, second feed pipeline; 123, discharge pipeline; 124, first vacuum and gas charging pipeline; 125, second vacuum and gas charging pipeline; 1261, first delivery pipeline; 1262, second delivery pipeline; 1263, third delivery pipeline; 127, vacuum pump connecting pipeline; 128, first feed valve; 129, second feed valve;

[0021] 13. Sealed container; 131. Sealed chamber; 132. Air intake pipeline;

[0022] 141. vacuum pump; 142. gas storage container; 15. stirring assembly; 151. stirring member; 152. driving member; 153. magnetic sealing member;

[0023] 16. Cooling parts;

[0024] 17. Alkali metal storage containers;

[0025] 18. Weighing device;

[0026] 19. Ultrasonic device; 191. Ultrasonic container; 192. Ultrasonic generating element;

[0027] 21. Nanofluid storage container;

[0028] 22. Nanofluid transport container;

[0029] 23. Adjust the valve. DETAILED DESCRIPTION

[0030] Exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is only a routine task for those skilled in the art who benefit from the content of this application.

[0031] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure and / or processing steps closely related to the scheme according to the present application are shown in the accompanying drawings, while other details that are not very relevant to the present application are omitted.

[0032] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in this application should have the common meanings understood by persons with ordinary skills in the field to which this application belongs.

[0033] In the description of the embodiments of the present application, “plurality” means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] The embodiments of the present application provide a nanofluid preparation system for mixing metal nanoparticles with alkali metals to form a nanofluid.

[0035] In some embodiments, Figure 1As shown, the preparation system may include a mixing container 11, a first feed line 121, a second feed line 122, a sealed container 13 and a discharge line 123. The mixing container 11 is configured to form a mixing chamber 111. The first feed line 121 is used to add metal nanoparticles to the mixing chamber 111. The second feed line 122 is used to add liquid alkali metal to the mixing chamber 111. The sealed container 13 is configured to form a sealed chamber 131 for accommodating metal nanoparticles. The metal nanoparticles are coated with solid alkali metal to form an integral part with the solid alkali metal.

[0036] See also Figure 2 The discharge pipeline 123 is connected to the sealed container 13 and is configured to be detachably connected to the first feed pipeline 121. When the discharge pipeline 123 is disassembled from the first feed pipeline 121, the sealed chamber 131 and the mixing chamber 111 can be sealed respectively; when the discharge pipeline 123 is connected to the first feed pipeline 121, the sealed chamber 131 can be communicated with the mixing chamber 111, so that the integrated part in the sealed container 13 can enter the mixing chamber 111 via the discharge pipeline 123 and the first feed pipeline 121 in sequence.

[0037] In the embodiment of the present application, a sealed container 13 and a discharge pipeline 123 are provided, and the sealed container 13 and the discharge pipeline 123 can be detachably sealed and connected with the first feed pipeline 121, so that the sealed container 13 and the discharge pipeline 123 can be removed from the first feed pipeline 121, so that the nanoparticles coated with solid alkali metals to form an integrated part are placed in the sealed container 13 in the glove box, and then the sealed container 13 and the discharge pipeline 123 are taken out of the glove box, and the discharge pipeline 123 is sealed and connected with the first feed pipeline 121, so that the integrated part formed by the solid alkali metal coating can enter the mixing chamber 111 through the first feed pipeline 121. In the process of the integrated part entering the mixing chamber 111 through the discharge pipeline 123 and the first feed pipeline 121, it is helpful to avoid the metal nanoparticles from being adsorbed on the inner wall of the mixing container 11 or the pipeline, and further helps to avoid the situation where the ratio of the metal nanoparticles and the alkali metal is inaccurate.

[0038] In some embodiments, the discharge pipeline 123 and the first feed pipeline 121 may be connected via a quick-release joint. The quick-release joint may be threaded.

[0039] In some embodiments, the preparation system may further include a mold. The liquid alkali metal mixed with the metal nanoparticles is poured into the mold and cooled to obtain an integral part. After obtaining the integral part, the integral part may be transferred to a sealed container 13 in a glove box filled with an inert gas for sealed storage.

[0040] The mold may be a rod-shaped mold.

[0041] In some embodiments, the inner wall of the mold may be formed with a non-wetting coating to prevent the integral part from adhering to the inner wall of the mold. The material of the non-wetting coating may be aluminum oxide or polytetrafluoroethylene.

[0042] In some embodiments, the inner diameter of the mold is smaller than the inner diameters of the discharge pipeline 123 and the first feed pipeline 121. This helps to avoid the problem that the integrated part is not easy to pass through the pipeline into the mixing chamber 111 due to its large size.

[0043] The size of the integral piece may be in the range of 10-20 mm, for example 10 mm,

[0044] In some embodiments, the preparation system may further include a first feed valve 128, a second feed valve 129, and a first vacuum and gas charging pipeline 124. The first feed valve 128 may be disposed on the first feed pipeline 121. The second feed valve 129 may be disposed on the discharge pipeline 123. The first vacuum and gas charging pipeline 124 is connected to the first feed pipeline 121 or the discharge pipeline 123, so that when the discharge pipeline 123 is connected to the first feed pipeline 121, the pipeline between the first feed valve 128 and the second feed valve 129 can be evacuated and filled with inert gas.

[0045] The embodiments of the present application can control the opening or closing of the first feed valve 128 and the second feed valve 129 to isolate or seal the sealed chamber 131 and the mixing chamber 111, which is relatively convenient; the first vacuum and inflation pipeline 124 is used to evacuate the pipeline between the first feed valve 128 and the second feed valve 129 and fill it with inert gas, which is beneficial for evacuating the pipeline between the first feed valve 128 and the second feed valve 129 after the discharge pipeline 123 is sealed and connected to the first feed pipeline 121, so as to avoid the introduction of air in the process of the integrated component entering the mixing chamber 111.

[0046] In some embodiments, if the sealed chamber 131 needs to be disconnected from the mixing chamber 111, the first feed valve 128 and the second feed valve 129 can be closed first, and then the discharge pipeline 123 and the first feed pipeline 121 can be disassembled. If the sealed chamber 131 needs to be connected to the mixing chamber 111, the discharge pipeline 123 and the first feed pipeline 121 can be connected first, and then the first vacuum and inflation pipeline 124 can be used to evacuate the pipeline between the first feed valve 128 and the second feed valve 129, and then the first feed valve 128 and the second feed valve 129 can be opened after evacuation.

[0047] In some embodiments, the operation of evacuating the pipeline between the first feed valve 128 and the second feed valve 129 and filling it with inert gas using the first vacuum and inflation pipeline 124 can be repeated multiple times, for example, 4 times, to ensure that the air in the pipeline can be fully discharged.

[0048] In some embodiments, the preparation system may include an air inlet line 132, and the sealed container 13 is further provided with an air inlet for connection with the air inlet line 132. The air inlet line 132 is used to provide air pressure to drive the integrated part smoothly from the sealed cavity 131 into the mixing container 11, so as to prevent the integrated part from falling only by gravity and possibly getting stuck in the pipeline.

[0049] After the discharge pipeline 123 is connected to the first feed pipeline 121, and the pipeline between the first feed valve 128 and the second feed valve 129 is evacuated and filled with inert gas by the first vacuum and inflation pipeline 124, the first feed valve 128 and the second feed valve 129 can be opened, and then gas is injected into the sealed cavity 131 through the intake pipeline 132. The gas is used to blow the integrated part from the sealed cavity 131 into the discharge pipeline 123, and enter the mixing container 11 through the first feed pipeline 121.

[0050] In some embodiments, the mixing container 11 may include a mixing body 112 and a mixing cover 113. The mixing cover 113 may be used to seal the mixing body 112 to form a mixing chamber 111.

[0051] In some embodiments, the discharge pipeline 123 can be disposed at the bottom of the sealed container 13. The first feed pipeline 121 can be disposed on the mixing cover 113 of the mixing container 11. The discharge pipeline 123 and the first feed pipeline 121 can both extend vertically so that the integrated component can smoothly fall into the mixing chamber 111 under the action of gravity and gas pressure.

[0052] The inner diameters of the discharge pipeline 123 and the first feed pipeline 121 and the diameters of the first feed valve 128 and the second feed valve 129 can be greater than the preset value, so that the integral part in the sealed container 13 can smoothly fall into the mixing chamber 111. In some embodiments, the preset value can be, for example, 25 mm. In some embodiments, the inner diameters of the discharge pipeline 123 and the first feed pipeline 121 and the diameters of the first feed valve 128 and the second feed valve 129 can be, for example, 30 mm.

[0053] In some embodiments, the preparation system may further include a stirring assembly 15. The stirring assembly 15 may be disposed in the mixing container 11, and is used to mechanically stir the material in the mixing chamber 111. The embodiment of the present application utilizes the stirring assembly 15 to mechanically stir the material in the mixing chamber 111, which is conducive to uniformly dispersing the metal nanoparticles in the mixing chamber 111 in the liquid alkali metal.

[0054] In some embodiments, the mixing container 11 may include a stirring through hole 114. The stirring assembly 15 may include a stirring member 151, a driving member 152, and a magnetic seal 153. The stirring member 151 enters the mixing container 11 from the stirring through hole 114. The driving member 152 may be disposed outside the mixing container 11 to drive the stirring member 151 to rotate. The magnetic seal 153 may be disposed outside the mixing container 11 to seal between the stirring member 151 and the stirring through hole 114 of the mixing container 11.

[0055] In the embodiment of the present application, the driving member 152 drives the stirring member 151 to rotate so as to stir the material in the mixing container 11; a magnetic seal 153 is provided between the stirring member 151 and the stirring through hole 114 of the mixing container 11, so as to ensure that the preparation system can operate for a long time in a high temperature environment, avoid problems such as alkali metal leakage caused by poor sealing between the stirring member 151 and the stirring through hole 114 of the mixing container 11, and at the same time avoid introducing new impurities into the mixing container 11.

[0056] In some embodiments, the stirring through hole 114 may be disposed on the mixing cover 113. In some embodiments, the magnetic seal 153 may be a magnetic sealing ring.

[0057] In some embodiments, the preparation system may further include a cooling element 16 for cooling the magnetic seal 153 , so as to ensure the sealing effect of the magnetic seal 153 .

[0058] In some embodiments, the cooling member 16 may be a cooling jacket that is cooled using oil cooling.

[0059] In some embodiments, the preparation system may further include an alkali metal storage container 17 and a second vacuum and gas charging pipeline 125. The alkali metal storage container 17 may be used to provide liquid alkali metal. The second vacuum and gas charging pipeline 125 may be used to evacuate the alkali metal storage container 17 and fill it with inert gas, so as to drive the liquid alkali metal from the alkali metal storage container 17 into the mixing container 11 via the second feed pipeline 122 by gas pressure.

[0060] The embodiment of the present application realizes the injection of liquid alkali metal from the alkali metal storage container 17 into the mixing container 11 via the second feed pipeline 122 in a gas pressure-driven manner through the second vacuum and inflation pipeline 125. This ensures that the process of the liquid alkali metal entering the mixing container 11 is carried out in an environment filled with inert gas to ensure the purity of the liquid alkali metal. At the same time, the use of gas pressure-driven method does not require the provision of an additional driving device, which is conducive to simplifying the structure of the preparation system.

[0061] In some embodiments, the preparation system may further include a vacuum pump 141, a gas storage container 142, and a vacuum pump connecting line 127. The gas storage container 142 may be used to store an inert gas. The second vacuum and gas charging line 125 may be connected to the gas storage container 142 and the vacuum pump connecting line 127, respectively. The vacuum pump 141 may be used to pump the inert gas in the gas storage container 142 to the first vacuum and gas charging line 124 and the second vacuum and gas charging line 125 via the vacuum pump connecting line 127.

[0062] In some embodiments, the preparation system may further include a heating element. The heating element may be used to heat the liquid alkali metal in the alkali metal storage container to prevent the liquid alkali metal from solidifying. Exemplarily, the liquid alkali metal in the alkali metal storage container may be in the range of 220-300°C.

[0063] In some embodiments, the preparation system may further include a weighing device 18. The weighing device 18 may be used to weigh the alkali metal storage container 17 and / or the mixing container 11, so as to determine the weight of the liquid alkali metal entering the mixing container 11. The embodiment of the present application uses the weighing device 18 to determine the weight of the liquid alkali metal entering the mixing container 11, so that the weight of the metal nanoparticles in the prepared nanofluid and the weight of the liquid alkali metal can meet the ratio requirements.

[0064] In some embodiments, the weighing device 18 may be a high-precision electronic scale.

[0065] In some embodiments, the preparation system may further include an ultrasonic device 19. The ultrasonic device 19 may be used to receive the material from the mixing container 11 to perform ultrasonic treatment on the material. The embodiment of the present application utilizes the ultrasonic device 19 to perform ultrasonic treatment on the material received from the mixing container 11, so that the metal nanoparticles can be more evenly dispersed in the liquid alkali metal.

[0066] In some embodiments, the ultrasonic device 19 may include an ultrasonic container 191 and an ultrasonic generator 192. The ultrasonic container 191 may be in fluid communication with the mixing container 11. The ultrasonic generator 192 may be disposed in the ultrasonic container 191 to perform ultrasonic treatment on the material in the ultrasonic container 191.

[0067] The embodiment of the present application configures the ultrasonic device 19 to include an ultrasonic container 191 and an ultrasonic generator 192, so that the material in the mixing container 11 can be introduced into the ultrasonic container 191 for ultrasonic treatment instead of being ultrasonically treated in the mixing container 11, thereby avoiding the deterioration of the sealing of the mixing container 11 due to ultrasound.

[0068] In some embodiments, the preparation system may further include a first material delivery pipeline 1261 and a plurality of regulating valves 23. The first material delivery pipeline 1261 may be used to connect the ultrasonic container 191 to the mixing body 112 of the mixing container 11. A plurality of regulating valves 23 may be provided on the first material delivery pipeline 1261 to control the on-off of the first material delivery pipeline 1261.

[0069] In some embodiments, the preparation system may further include a control device, which may be used to determine the working parameters of the ultrasonic generator 192 according to the melting point of the metal nanoparticles and the temperature of the material in the ultrasonic container 191 .

[0070] The embodiment of the present application uses a control device to determine the working parameters of the ultrasonic generator 192 to prevent ultrasound from causing a significant increase in fluid temperature, causing the nanoparticles to melt and form an alloy with sodium, thereby causing the performance of the nanofluid to deteriorate. At the same time, it prevents the local temperature of the nanofluid from being too high, thereby causing alkali metal boiling or flashing, etc., which brings safety hazards.

[0071] In some embodiments, the working parameters of the ultrasonic generator 192 may include the ultrasonic time of the ultrasonic wave emitted by the ultrasonic generator 192 and the power of the ultrasonic generator 192. In some embodiments, the control device may set the ultrasonic time to not exceed a preset time to avoid the phenomenon of alkali metal boiling or flashing due to excessive local temperature of the nanofluid.

[0072] Usually, the ultrasonic frequency emitted by the ultrasonic generator 192 is fixed. In some embodiments, the ultrasonic device 19 may include multiple ultrasonic generators 192 with different ultrasonic frequencies, and the control device may also select an ultrasonic generator 192 with a suitable ultrasonic frequency according to the melting point of the metal nanoparticles and the temperature of the material in the ultrasonic container 191.

[0073] In some embodiments, the preparation system may further include a second material delivery pipeline 1262 and a nanofluid storage container 21. The second material delivery pipeline 1262 is used to connect the ultrasound container 191 with the nanofluid storage container 21. The nanofluid storage container 21 is used to store the nanofluid obtained after the ultrasound treatment.

[0074] In some embodiments, the preparation system may further include a third material delivery pipeline 1263 and a nanofluid transport container 22. The third material delivery pipeline 1263 is used to connect the nanofluid storage container 21 to the nanofluid transport container 22. The nanofluid transport container 22 is used to store the nanofluid to be transported in the nanofluid storage container 21.

[0075] In some embodiments, the second material delivery pipeline 1262 and the third material delivery pipeline 1263 may be provided with regulating valves 23 respectively, which are used to control the on-off of the second material delivery pipeline 1262 and the third material delivery pipeline 1263 respectively.

[0076] The embodiments of the present application also provide a method for preparing a nanofluid, which is used to mix metal nanoparticles with alkali metals to form a nanofluid. Figure 3 As shown, the preparation method may at least include the following steps S1 to S3.

[0077] S1. The metal nanoparticles are coated with a solid alkali metal to form an integral body with the solid alkali metal.

[0078] S2. Adding the integral part into liquid alkali metal.

[0079] S3, uniformly mixing the integral member with liquid alkali metal to form a nanofluid.

[0080] The inventor of the present application has found that in the related art, metal nanoparticles are directly added to a mixing container through a feeding pipeline of a nanofluid preparation system to mix with liquid alkali metal in the mixing container. Since the surface area of ​​metal nanoparticles is usually relatively large, if metal nanoparticles are directly added to liquid alkali metal through a feeding pipeline, the metal nanoparticles will be adsorbed on the inner walls of all containers or pipelines that can be contacted during the feeding process, thereby causing an inaccurate ratio of metal nanoparticles to alkali metal.

[0081] In the embodiment of the present application, nanoparticles are coated with solid alkali metal to form an integral part, and then the integral part is added into liquid alkali metal. This can prevent the metal nanoparticles from being adsorbed on the inner wall of the container or pipeline, thereby helping to avoid an inaccurate ratio of the metal nanoparticles and the alkali metal.

[0082] In some embodiments, the material of the metal nanoparticles may be one or more transition metals with a melting point greater than or equal to 900° C. and relatively high interatomic strength. For example, the metal nanoparticles may be titanium nanoparticles, manganese nanoparticles, etc. The alkali metal in the embodiment of the present application may be metallic sodium.

[0083] In some embodiments, the size of the metal nanoparticles may be less than 100 nm, such as 50 nm. In some embodiments, the ratio of the mass of the metal nanoparticles to the total mass of the metal nanoparticles and the alkali metal may be in the range of 0.1 wt% to 10 wt%.

[0084] In some embodiments, the one-piece may be in the shape of a rod.

[0085] In some embodiments, step S1 may include: in an inert atmosphere, heating a solid alkali metal to form a liquid alkali metal, mixing the liquid alkali metal with metal nanoparticles, and allowing the liquid alkali metal to cool and solidify to form an integral part.

[0086] In some embodiments, step S1 can be performed in a glove box filled with an inert gas. The inert gas can be argon, helium, etc. The target weight of metal nanoparticles and a small amount of solid alkali metal (e.g., 20-30 g) are weighed in a glove box filled with an inert gas, and the weighed metal nanoparticles and the solid alkali metal are heated and mixed so that the heated liquid alkali metal can coat the metal nanoparticles. The liquid alkali metal coated with the metal nanoparticles is then poured into a rod-shaped mold for cooling to obtain an integral part.

[0087] It is easy to understand that the total amount of the solid alkali metal added in step S1 and the liquid alkali metal added in step S2 is the content of the alkali metal in the nanofluid.

[0088] In some embodiments, the preparation method of the embodiments of the present application can be implemented using the preparation system provided by any embodiment of the present application.

[0089] In some embodiments, step S2 may include: providing a sealed container and a mixing container; placing the integrated component into the sealed container under an inert atmosphere; connecting the sealed container to the mixing container through a connecting pipe under an atmospheric environment; evacuating the connecting pipe, and then injecting an inert gas into the connecting pipe; and connecting the connecting pipe so that the integrated component in the sealed container enters the mixing container via the connecting pipe.

[0090] The method provided in the embodiments of the present application can prevent the integrated component from being contaminated by placing the integrated component into a sealed container under an inert atmosphere; after connecting the sealed container to the mixing container through a connecting pipe under an atmospheric environment, the connecting pipe is evacuated and injected with an inert gas, and then the connecting pipe is opened so that the integrated component in the sealed container can enter the mixing container via the connecting pipe, which can further prevent the integrated component from being contaminated by air in the process of entering the connecting pipe from the sealed container.

[0091] In some embodiments, the integrated part can be transferred into a sealed container in a glove box filled with inert gas for sealed storage.

[0092] In some embodiments, the sealed container in step S2 can be the sealed container 13 in the preparation system provided in any embodiment of the present application; the mixing container can be the mixing container 11 in the preparation system provided in any embodiment of the present application; the connecting pipeline can be the first feed pipeline 121 and the discharge pipeline 123 in the preparation system provided in any embodiment of the present application.

[0093] In some embodiments, the cross-sectional dimension of the integrated part made in step S1 is smaller than the inner diameter of the connecting pipeline to prevent the integrated part from sticking to the connecting pipeline. For example, the cross-sectional dimension of the integrated part made in step S1 is smaller than the inner diameter of the discharge pipeline 123 and the first feed pipeline 121, and smaller than the diameter of the first feed valve 128 and the second feed valve 129 to prevent the integrated part from sticking to the pipeline or valve and not being able to smoothly enter the mixing container 11.

[0094] In some embodiments, step S3 may include: S31, mechanically stirring the integral part and the liquid alkali metal to form a mixed fluid. In the embodiments of the present application, mechanically stirring the integral part and the liquid alkali metal facilitates uniform dispersion of metal nanoparticles in the mixed fluid.

[0095] In some embodiments, step S31 may include: after the integral part is added to the mixing container through the connecting pipeline, waiting for a first preset time to allow the alkali metal in the integral part to completely melt; thereafter, mechanically stirring the material in the mixing container 11 using the stirring member 151 .

[0096] The method provided in the embodiment of the present application waits for a first preset time to allow the alkali metal in the integral part to completely melt, and then uses the stirring member 151 to mechanically stir the material in the mixing container 11, so as to prevent the stirring member 151 from throwing the integral part to the inner wall of the mixing container 11 and adhering to the inner wall when the alkali metal is not completely melted, thereby hindering the full dispersion of the metal nanoparticles in the liquid alkali metal.

[0097] In some embodiments, when the stirring member 151 is used to mechanically stir the materials in the mixing container, the rotation speed of the stirring member 151 should not be too high when the stirring member 151 is first started, for example, the rotation speed of the stirring member 151 is less than 100 rpm. If the rotation speed of the stirring member 151 is relatively high, the metal nanoparticles are more likely to be thrown onto the inner wall of the mixing chamber 111 during the stirring process.

[0098] In some embodiments, the step of mechanically stirring the material in the mixing container 11 using the stirring member 151 may include: starting the stirring member 151 at a first speed, and rotating the stirring member 151 at the first speed for a first preset time; then, rotating the stirring member 151 at a second speed for a second preset time; then, rotating the stirring member 151 at a third speed for a third preset time; then, rotating the stirring member 151 at a fourth speed for a fourth preset time. The first speed, the second speed, the third speed, and the fourth speed increase in sequence.

[0099] The method provided in the embodiment of the present application sequentially controls the stirring member 151 to rotate at different rotation speeds for different preset time periods, which is beneficial for enabling the metal nanoparticles to be fully dispersed in the liquid alkali metal.

[0100] In such an embodiment, the material in the mixing container 11 can be mechanically stirred by the stirring member 151 in the following manner. When the material enters the mixing chamber 111 and waits for the alkali metal to be fully melted (for example, wait for 15 minutes), the driving member 152 is controlled to start the stirring member 151 at a speed less than 100 rpm, and after 3 minutes, the speed of the stirring member 151 is increased to 100 rpm and stably operated for 15 minutes; after stably operating for 15 minutes, the speed of the stirring member 151 is increased to 250 rpm and stably operated for 15 minutes; after stably operating for 15 minutes again, the speed of the stirring member 151 is continued to be increased to 400 rpm and continuously operated for 12. During the above stirring process, the stirring temperature can be maintained in the range of 250-300°C.

[0101] In some embodiments, step S3 may further include: S32, performing ultrasonic treatment on the mixed fluid to form a nanofluid, so that the metal nanoparticles can be more evenly dispersed in the liquid alkali metal.

[0102] In some embodiments, during the ultrasonic treatment, the mixed fluid is introduced into an ultrasonic container 191 provided with an ultrasonic generator 192 for ultrasonic treatment.

[0103] In the embodiment of the present application, the mixed fluid is introduced into an ultrasonic container 191 provided with an ultrasonic generator 192 for ultrasonic treatment, without the need to perform ultrasonic treatment in the mixing container 11, thereby avoiding the deterioration of the sealing of the mixing container 11 caused by ultrasound.

[0104] In some embodiments, the frequency, duration, and power of the ultrasonic treatment are determined according to the melting point of the metal nanoparticles and the temperature of the mixed fluid in the ultrasonic container. The embodiments of the present application determine the frequency, duration, and power of the ultrasonic treatment according to the melting point of the metal nanoparticles and the temperature of the mixed fluid in the ultrasonic container 191 to prevent ultrasound from causing a significant increase in the fluid temperature, causing the nanoparticles to melt and form an alloy with sodium, thereby causing the performance of the nanofluid to deteriorate; at the same time, it prevents the local temperature of the nanofluid from being too high, thereby causing the alkali metal to boil or flash, etc., which brings safety hazards.

[0105] In some embodiments, the melting point of the metal nanoparticles is higher than 900°C, the temperature of the mixed fluid in the ultrasonic container 191 is 220-300°C, and during the ultrasonic treatment, the ultrasonic frequency of the ultrasonic wave emitted by the ultrasonic generator 192 can be less than or equal to 20kHz, the power of the ultrasonic generator 192 can be less than or equal to 400W, and the ultrasonic time is less than 3 minutes. Exemplarily, the ultrasonic frequency of the ultrasonic wave emitted by the ultrasonic generator 192 can be 19.5kHz, and the power of the ultrasonic generator 192 can be 400W. During the ultrasonic treatment, the heat generated by the ultrasonic wave is relatively large. By setting the ultrasonic frequency to 19.5kHz and the power to 400W, the heat generated by the ultrasonic wave can be relatively small, and the temperature of the nanofluid is also low, so as to prevent the metal nanoparticles from melting and forming an alloy with the liquid alkali metal, and at the same time prevent the local temperature of the nanofluid from being too high, so as to cause the alkali metal to boil or flash, etc., which brings safety hazards.

[0106] In some embodiments, before charging the alkali metal into the alkali metal storage container 17 for the first time, the alkali metal storage container 17 may be evacuated and filled with an inert gas so that the water and oxygen content in the alkali metal storage container 17 does not exceed 50 ppm.

[0107] The preparation method and preparation system of the embodiment of the present application uniformly disperse the nanoparticles added to the liquid alkali metal in sequence through mechanical stirring and ultrasonic treatment, and the prepared nanofluid has good uniformity.

[0108] The preparation method and preparation system of the embodiments of the present application are suitable for the preparation of kilogram-level sodium-based nanofluids.

[0109] The kilogram-level sodium-based nanofluid preparation method and preparation system of the embodiment of the present application can be used to carry out various performance test experiments of sodium-based nanofluids in suspension stability, thermal stability, etc., so as to determine the influence of different preparation processes on the performance of sodium-based nanofluids, and provide verification data for the design of subsequent engineering-level sodium-based nanofluid coolant preparation process and preparation system.

[0110] The method for preparing nanofluids according to the embodiments of the present application is described below in conjunction with specific embodiments.

[0111] (1) When the alkali metal storage container 17 is charged with sodium for the first time, the alkali metal storage container 17, the mixing container 11, the ultrasonic container 191 and other related equipment and connecting pipes need to be evacuated and replaced with argon. When the water and oxygen impurity contents are both lower than 50ppm, the sodium charging operation can be carried out.

[0112] (2) The alkali metal in the alkali metal storage container 17 is heated to 250°C.

[0113] (3) In a glove box, a high-precision scale is used to quantitatively weigh target transition metal element nanoparticles and a small amount of solid metallic sodium. After the solid metallic sodium is heated into a liquid, the nanoparticles are poured into the liquid sodium for mixing.

[0114] (4) The liquid sodium containing nanoparticles mixed in step (3) is introduced into a mold, and after cooling, a thin rod-shaped integral sample with a diameter of about 10 mm is formed.

[0115] (5) Add the liquid sodium prepared in step (2) into the mixing container 11 in a quantitative manner.

[0116] (6) Place the one-piece sample prefabricated in step (4) into a sealed container 13.

[0117] (7) Install the sealed container 13 containing the one-piece sample in step (6) into the first feed pipe 121.

[0118] (8) The pipeline between the sealed container 13 and the mixing container 11 is evacuated and replaced with argon. After repeating this process 4 times, the pressure of this section of the pipeline is supplemented to normal pressure.

[0119] (9) Argon gas is filled into the mixing container 11 so that the gas pressure in the mixing chamber 111 of the mixing container 11 is slightly positive, for example, less than 3 kPa.

[0120] (10) Open the first feed valve 128 and the second feed valve 129 between the sealed container 13 and the mixing container 11 in sequence, and blow the sample into the mixing container 11 by blowing air into the sealed container 13.

[0121] (11) Start the oil cooling system to cool the magnetic sealing ring position of the stirring assembly 15.

[0122] (12) After the integrated sample falls into the mixing container 11, wait for 15 minutes, then start the stirring element 151 at a low speed. After 3 minutes, increase the speed of the stirring element 151 to 100 rpm. After running stably for 15 minutes, increase the speed to 250 rpm. After running stably for another 15 minutes, increase the speed to 400 rpm again and continue running for 12 hours.

[0123] (13) Then, the stirring is stopped, and the liquid metallic sodium in the mixing container 11 is introduced into the ultrasonic container 191 by driving the argon gas pressure.

[0124] (14) The nanoparticles were dispersed secondary in the basic sodium solution for 30 min using an ultrasonic generator with an ultrasonic frequency of 19.5 kHz and a power of 400 W.

[0125] (15) The sodium-based nanofluid dispersed by ultrasonic in step (14) is transferred to the nanofluid storage container 21 again by argon driving, thereby completing the preparation of the sodium-based nanofluid.

[0126] In some embodiments, the embodiments of the present application utilize the atomic bonds between nanoparticles of transition metal elements with greater electronegativity and metallic sodium, so that there is a certain charge transfer from the sodium atoms of the base liquid surrounding the nanoparticles to the nanoparticles at the center, and finally the periphery of the nanoparticles is electropositive. This results in electrostatic repulsion between nanoparticle clusters, so that the nanoparticles in the base liquid are not easy to agglomerate and have better dispersibility.

[0127] Regarding the embodiments of the present application, it should also be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other to obtain new embodiments.

[0128] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a nanofluid, for mixing metal nanoparticles with alkali metals to form a nanofluid, characterized in that: The method comprises: S1, coating the metal nanoparticles with a solid alkali metal to form an integral part with the solid alkali metal; S2, adding the integrated part into liquid alkali metal; S3, uniformly mixing the integral member and the liquid alkali metal to form the nanofluid.

2. The preparation method according to claim 1, characterized in that: The S1 step includes: In an inert atmosphere, the solid alkali metal is heated to form a liquid alkali metal, which is then mixed with the metal nanoparticles, and the liquid alkali metal is cooled and solidified to form the integrated component.

3. The preparation method according to claim 1, characterized in that: The S3 step includes: S31, mechanically stirring the integral member and the liquid alkali metal to form a mixed fluid.

4. The preparation method according to claim 3, characterized in that: The S2 step includes: Provide sealed containers and mixing containers; Under an inert atmosphere, placing the integrated component into the sealed container; Under atmospheric environment, connecting the sealed container to the mixing container through a connecting pipeline; The connecting pipeline is evacuated, and then an inert gas is injected into the connecting pipeline; The connecting pipeline is opened so that the integral part in the sealed container enters the mixing container through the connecting pipeline.

5. The preparation method according to claim 4, characterized in that: The step S31 includes: After the integral part is added into the mixing container through the connecting pipeline, waiting for a first preset time to allow the alkali metal in the integral part to be completely melted; Afterwards, the materials in the mixing container are mechanically stirred by using a stirring member.

6. The preparation method according to claim 5, characterized in that: The step of mechanically stirring the materials in the mixing container by using a stirring member comprises: Starting the stirring member at a first speed, and rotating the stirring member at the first speed for a first preset time; Then, the stirring member is rotated at a second speed for a second preset time; Then, rotating the stirring member at a third speed for a third preset time; Then, rotating the stirring member at a fourth speed for a fourth preset time; Among them, the first speed, the second speed, the third speed, and the fourth speed increase in sequence.

7. The preparation method according to claim 4, characterized in that: The cross-sectional dimension of the integrated piece manufactured in step S1 is smaller than the inner diameter of the connecting pipeline.

8. The preparation method according to claim 3, characterized in that: The S3 step further includes: S32, performing ultrasonic treatment on the mixed fluid to form the nanofluid.

9. The preparation method according to claim 8, characterized in that: In the ultrasonic treatment, the mixed fluid is introduced into an ultrasonic container provided with an ultrasonic generator for ultrasonic treatment.

10. The preparation method according to claim 9, characterized in that: The frequency, duration and power of ultrasonic treatment are determined according to the melting point of the metal nanoparticles and the temperature of the mixed fluid in the ultrasonic container.

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