System and method for preparing nanofluid

Abstract

Embodiments of the present application relate to the technical field of nanofluid preparation, and particularly relate to a nanofluid preparation system and a preparation method for mixing metal nanoparticles and alkali metals to form a nanofluid. The preparation system comprises: a mixing container configured to form a mixing cavity; a first feeding pipeline for adding metal nanoparticles into the mixing cavity; a second feeding pipeline for adding liquid alkali metals into the mixing cavity; a sealed container configured to form a sealed cavity and used for containing the metal nanoparticles, wherein the metal nanoparticles are coated by solid alkali metals to form an integral piece with the solid alkali metals; and a discharging pipeline connected with the sealed container and configured to be detachably connected with the first feeding pipeline. According to the embodiments of the present application, the sealed container and the discharging pipeline are arranged, so that the metal nanoparticles can be coated by the solid alkali metals to form an integral piece in the sealed container in a glove box, and then the metal nanoparticles are fed into the mixing cavity through the first feeding pipeline.

Description

Technical Field

[0001] This application relates to the field of nanofluid preparation technology, specifically to a nanofluid preparation system and preparation method. Background Technology

[0002] Compared to previous nuclear energy systems, fourth-generation nuclear energy systems require higher reliability, safety, and economic efficiency. Among these, the sodium-cooled fast reactor (SNCR), a type of fourth-generation nuclear energy system, primarily uses liquid metallic sodium as its coolant. While metallic sodium offers excellent heat transfer performance, neutron economy, and material compatibility, its high chemical reactivity presents a constraint on the development of SNCRs. For example, if a breach occurs in the cooling main pipeline or a heat exchanger ruptures, the leaked metallic sodium, upon contact with oxygen or water in the environment, can undergo a violent sodium-fire or sodium-water reaction, releasing a large amount of heat.

[0003] To mitigate the aforementioned reactive accidents, sodium-based nanofluids, which offer better heat transfer performance and lower chemical reactivity, can replace traditional metallic sodium coolants. However, the current preparation results of sodium-based nanofluids are not ideal. Summary of the Invention

[0004] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0005] The inventors of this application discovered that the prepared nanofluids suffer from inaccurate proportions. They further discovered that this is because the nanoparticles have a large specific surface area; when the nanoparticles are fed into a container to mix with solid alkali metals, they adhere to the inner wall of the container or pipe in contact with them, preventing the actual proportions of nanoparticles mixed with the liquid alkali metals from meeting the required proportions.

[0006] To address the aforementioned technical problems, embodiments of this application provide a nanofluid preparation system and method for mixing metal nanoparticles with alkali metals to form nanofluids.

[0007] In a first aspect, embodiments of this application provide a nanofluid preparation system, comprising: a mixing container configured to form a mixing chamber; a first feed line for adding metal nanoparticles into the mixing chamber; a second feed line for adding liquid alkali metal into the mixing chamber; a sealing container configured to form a sealing chamber for containing the metal nanoparticles, wherein the metal nanoparticles are coated with solid alkali metal to form an integral part with the solid alkali metal; and a discharge line connected to the sealing container, configured to be detachably connected to the first feed line, wherein when the discharge line is disconnected from the first feed line, the sealing chamber and the mixing chamber can be sealed respectively; when the discharge line is connected to the first feed line, the sealing chamber can communicate with the mixing chamber, thereby allowing the integral part in the sealing container to enter the mixing chamber sequentially via the discharge line and the first feed line.

[0008] The inventors of this application have discovered that in related technologies, metal nanoparticles are directly added to the mixing chamber of a mixing container via the first feed pipe of a nanofluid preparation system. Because metal nanoparticles have a large specific surface area, directly feeding them into the mixing chamber via the first feed pipe causes them to adsorb onto all surfaces they can contact during the feeding process, leading to inaccurate ratios of metal nanoparticles and alkali metals.

[0009] The embodiments of this application, by setting up a sealed container and a discharge pipe, and enabling the sealed container and discharge pipe to be detachably and sealed to a first feed pipe, allow the sealed container and discharge pipe to be removed from the first feed pipe. This allows nanoparticles coated with solid alkali metal to be placed into the sealed container inside a glove box. Then, the sealed container and discharge pipe are removed from the glove box, and the discharge pipe is sealed to the first feed pipe, allowing the solid alkali metal-coated component to enter the mixing chamber via the first feed pipe. During the process of the component entering the mixing chamber via the discharge pipe and the first feed pipe, it helps to prevent the metal nanoparticles from adsorbing onto the inner wall of the mixing container or pipe, thereby helping to avoid inaccurate ratios of metal nanoparticles and alkali metal.

[0010] Secondly, embodiments of this application provide a method for preparing nanofluids, wherein the preparation method uses the preparation system of the first aspect of this application to prepare nanofluids.

[0011] These and other advantages of this application will become more apparent from the following detailed description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0012] To further illustrate the above and other advantages and features of this application, the specific embodiments of this application will be described in more detail below with reference to the accompanying drawings. The drawings, together with the following detailed description, are included in and form a part of this specification. Elements having the same function and structure are indicated by the same reference numerals. It should be understood that these drawings only depict typical examples of this application and should not be considered as limiting the scope of this application.

[0013] Figure 1 This is a schematic diagram of the structure of a nanofluid preparation system according to an embodiment of this application.

[0014] Figure 2 yes Figure 1 A partially enlarged schematic diagram of the mixing container of the preparation system shown.

[0015] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding.

[0016] Explanation of reference numerals in the attached figures:

[0017] 11. Mixing container; 111. Mixing chamber; 112. Mixing body; 113. Mixing cover; 114. Stirring hole;

[0018] 121. First feed line; 122. Second feed line; 123. Discharge line; 124. First vacuum and gas filling line; 125. Second vacuum and gas filling line; 1261. First conveying line; 1262. Second conveying line; 1263. Third conveying line; 127. Vacuum pump connection line; 128. First feed valve; 129. Second feed valve;

[0019] 13. Sealed container; 131. Sealed cavity; 132. Air intake pipe;

[0020] 141. Vacuum pump; 142. Gas storage container; 15. Stirring assembly; 151. Stirring component; 152. Drive component; 153. Magnetic seal;

[0021] 16. Cooling components;

[0022] 17. Alkali metal storage containers;

[0023] 18. Weighing device;

[0024] 19. Ultrasonic device; 191. Ultrasonic container; 192. Ultrasonic generator;

[0025] 21. Nanofluid storage container;

[0026] 22. Nanofluid transport containers;

[0027] 23. Adjust the valve. Detailed Implementation

[0028] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0029] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0030] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning as understood by a person with ordinary skills in the field to which this application pertains.

[0031] In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] Embodiments of this application provide a nanofluid preparation system for mixing metal nanoparticles with alkali metals to form nanofluids.

[0033] In some embodiments, such as Figure 1 As 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 containing the metal nanoparticles. The metal nanoparticles are coated with solid alkali metal to form an integral part with the solid alkali metal.

[0034] See Figure 2The discharge pipe 123 is connected to the sealed container 13 and is configured to be detachably connected to the first feed pipe 121. When the discharge pipe 123 is disconnected from the first feed pipe 121, the sealing chamber 131 and the mixing chamber 111 can be sealed respectively. When the discharge pipe 123 is connected to the first feed pipe 121, the sealing chamber 131 can communicate with the mixing chamber 111, so that the integral component in the sealed container 13 can enter the mixing chamber 111 in sequence through the discharge pipe 123 and the first feed pipe 121.

[0035] The embodiments of this application, by setting up a sealed container 13 and a discharge pipe 123, and making the sealed container 13 and the discharge pipe 123 detachably and sealed to the first feed pipe 121, allow the sealed container 13 and the discharge pipe 123 to be removed from the first feed pipe 121. This allows nanoparticles coated with solid alkali metal to be placed into the sealed container 13 inside a glove box. Then, the sealed container 13 and the discharge pipe 123 are removed from the glove box, and the discharge pipe 123 is sealed to the first feed pipe 121, allowing the solid alkali metal coated component to enter the mixing chamber 111 via the first feed pipe 121. During the process of the component entering the mixing chamber 111 via the discharge pipe 123 and the first feed pipe 121, it is beneficial to avoid the adsorption of metal nanoparticles on the inner wall of the mixing container 11 or the pipes, thereby helping to avoid inaccurate ratios of metal nanoparticles and alkali metal.

[0036] In some embodiments, the metal nanoparticles can 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 can be titanium nanoparticles, manganese nanoparticles, etc. In the embodiments of this application, the alkali metal can be sodium metal.

[0037] In some embodiments, the size of the metal nanoparticles may be less than 100 nm, for example, 50 nm. In some embodiments, the ratio between the mass of the metal nanoparticles and the total mass of the metal nanoparticles and the alkali metal may be in the range of 0.1 wt% to 10 wt%.

[0038] In some embodiments, the integral component may be rod-shaped.

[0039] In some embodiments, the discharge pipe 123 and the first feed pipe 121 can be connected by a quick-release connector. The quick-release connector can be a threaded connection.

[0040] In some embodiments, the preparation system may further include a mold. Liquid alkali metal mixed with metal nanoparticles is poured into the mold and cooled to obtain a monolithic part. After obtaining the monolithic part, it can be transferred to a sealed container 13 for sealed storage in a glove box filled with inert gas.

[0041] The mold can be a rod-shaped mold.

[0042] In some embodiments, a non-wetting coating may be formed on the inner wall of the mold 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, etc.

[0043] In some embodiments, the inner diameter of the mold is smaller than the inner diameter of the discharge pipe 123 and the first feed pipe 121. This helps to avoid the situation where the large size of the integral part makes it difficult to smoothly pass through the pipes into the mixing chamber 111.

[0044] The dimensions of the integrated component can be within the range of 10-20mm, for example, 10mm.

[0045] 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 filling line 124. The first feed valve 128 may be disposed in the first feed line 121. The second feed valve 129 may be disposed in the discharge line 123. The first vacuum and gas filling line 124 is connected to either the first feed line 121 or the discharge line 123, so that when the discharge line 123 is connected to the first feed line 121, it can evacuate and fill the line between the first feed valve 128 and the second feed valve 129 with inert gas.

[0046] The embodiments of this application can conveniently isolate or seal the sealing chamber 131 and the mixing chamber 111 by controlling the opening or closing of the first feed valve 128 and the second feed valve 129; the first vacuum and gas filling pipeline 124 is used to evacuate the pipeline between the first feed valve 128 and the second feed valve 129 and to fill it with inert gas. This is beneficial to evacuate the pipeline between the first feed valve 128 and the second feed valve 129 after sealing the discharge pipeline 123 with the first feed pipeline 121, so as to avoid introducing air during the process of the integral part entering the mixing chamber 111.

[0047] In some embodiments, if it is necessary to disconnect the sealing chamber 131 from the mixing chamber 111, the first feed valve 128 and the second feed valve 129 can be closed first, and then the discharge pipe 123 and the first feed pipe 121 can be disassembled. If it is necessary to connect the sealing chamber 131 to the mixing chamber 111, the discharge pipe 123 and the first feed pipe 121 can be connected first, and then the pipe between the first feed valve 128 and the second feed valve 129 can be evacuated using the first vacuum and gas filling pipe 124. After evacuation, the first feed valve 128 and the second feed valve 129 can be opened.

[0048] In some embodiments, the operation of evacuating and filling the pipeline between the first feed valve 128 and the second feed valve 129 using the first vacuum and gas filling pipeline 124 can be performed repeatedly, for example, four times, to ensure that the air in the pipeline can be fully discharged.

[0049] In some embodiments, the preparation system may include an air inlet pipe 132, and the sealed container 13 is further provided with an air inlet for connection to the air inlet pipe 132. The air inlet pipe 132 is used to provide air pressure to drive the integral part smoothly from the sealed cavity 131 into the mixing container 11, so as to prevent the integral part from getting stuck in the pipe due to gravity falling alone.

[0050] After the discharge pipe 123 is connected to the first feed pipe 121, and the first vacuum and gas filling pipe 124 is used to evacuate the pipe between the first feed valve 128 and the second feed valve 129 and fill it with inert gas, the first feed valve 128 and the second feed valve 129 can be opened. Then, gas is filled into the sealing cavity 131 through the gas inlet pipe 132. The gas is used to blow the integral part from the sealing cavity 131 into the discharge pipe 123 and into the mixing container 11 through the first feed pipe 121.

[0051] 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 cavity 111.

[0052] In some embodiments, the discharge pipe 123 may be disposed at the bottom of the sealed container 13. The first feed pipe 121 may be disposed on the mixing cover 113 of the mixing container 11. Both the discharge pipe 123 and the first feed pipe 121 may extend vertically so that the integral piece can fall smoothly into the mixing chamber 111 under the action of gravity and gas pressure.

[0053] The inner diameters of the discharge pipe 123 and the first feed pipe 121, as well as the through diameters of the first feed valve 128 and the second feed valve 129, can all be larger than preset values, so that the integral component inside the sealed container 13 can smoothly fall into the mixing chamber 111. In some embodiments, the preset values ​​can be, for example, 25 mm. In some embodiments, the inner diameters of the discharge pipe 123 and the first feed pipe 121, as well as the through diameters of the first feed valve 128 and the second feed valve 129, can be, for example, 30 mm.

[0054] 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 for mechanically stirring the material in the mixing chamber 111. The embodiments of this application utilize the stirring assembly 15 to mechanically stir the material in the mixing chamber 111, which is beneficial for the uniform dispersion of metal nanoparticles in the liquid alkali metal within the mixing chamber 111.

[0055] In some embodiments, the mixing container 11 may include a stirring through-hole 114. The stirring assembly 15 may include a stirring element 151, a driving element 152, and a magnetic seal 153. The stirring element 151 enters the mixing container 11 through the stirring through-hole 114. The driving element 152 may be disposed outside the mixing container 11 for driving the stirring element 151 to rotate. The magnetic seal 153 may be disposed outside the mixing container 11 for sealing the stirring element 151 with the stirring through-hole 114 of the mixing container 11.

[0056] In the embodiments of this application, the stirring element 151 is driven to rotate by the driving element 152 to stir the material in the mixing container 11. A magnetic sealing element 153 is provided between the stirring element 151 and the stirring through hole 114 of the mixing container 11. This can ensure that the preparation system can operate for a long time in a high-temperature environment, and avoid problems such as alkali metal leakage caused by poor sealing between the stirring element 151 and the stirring through hole 114 of the mixing container 11. At the same time, it can also prevent the introduction of new impurities into the mixing container 11.

[0057] In some embodiments, the stirring through-hole 114 may be provided on the mixing cover 113. In some embodiments, the magnetic seal 153 may be a magnetic sealing ring.

[0058] In some embodiments, the preparation system may further include a cooling element 16 for cooling the magnetic seal 153. This ensures the sealing effect of the magnetic seal 153.

[0059] In some embodiments, the cooling element 16 may be a cooling jacket that utilizes oil cooling.

[0060] In some embodiments, the preparation system may further include an alkali metal storage container 17 and a second vacuum and gas filling line 125. The alkali metal storage container 17 may be used to provide liquid alkali metal. The second vacuum and gas filling line 125 may be used to evacuate the alkali metal storage container 17 and fill it with inert gas, so as to use gas pressure to drive the liquid alkali metal from the alkali metal storage container 17 into the mixing container 11 via the second feed line 122.

[0061] In the embodiments of this application, liquid alkali metal is injected from the alkali metal storage container 17 into the mixing container 11 via the second feed pipe 122 through the second vacuum and gas filling pipe 125 in a pneumatically driven manner. This ensures that the process of liquid alkali metal entering the mixing container 11 is carried out in an environment filled with inert gas, so as to ensure the purity of liquid alkali metal. At the same time, the pneumatically driven method eliminates the need for an additional driving device, which helps to simplify the structure of the preparation system.

[0062] In some embodiments, the preparation system may further include a vacuum pump 141, a gas storage container 142, and a vacuum pump connection line 127. The gas storage container 142 may be used to store inert gas. A second vacuum and filling line 125 may be connected to the gas storage container 142 and the vacuum pump connection 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 filling line 124 and the second vacuum and filling line 125 via the vacuum pump connection line 127.

[0063] In some embodiments, the preparation system may further include a heating element. The heating element can 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.

[0064] In some embodiments, the preparation system may further include a weighing device 18. The weighing device 18 can be used to weigh the alkali metal storage container 17 and / or the mixing container 11 to determine the weight of the liquid alkali metal entering the mixing container 11. Embodiments of this application utilize the weighing device 18 to determine the weight of the liquid alkali metal entering the mixing container 11, ensuring that the weight of the metal nanoparticles in the prepared nanofluid meets the required ratio to the weight of the liquid alkali metal.

[0065] In some embodiments, the weighing device 18 may be a high-precision electronic scale.

[0066] In some embodiments, the preparation system may further include an ultrasonic device 19. The ultrasonic device 19 can be used to receive material from the mixing container 11 for ultrasonic treatment of the material. Embodiments of this application utilize the ultrasonic device 19 to ultrasonically treat the material received from the mixing container 11, which allows for more uniform dispersion of metal nanoparticles in the liquid alkali metal.

[0067] 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 for ultrasonically treating the material in the ultrasonic container 191.

[0068] The embodiments of this application configure the ultrasonic device 19 to include an ultrasonic container 191 and an ultrasonic generator 192, which enables the material in the mixing container 11 to be introduced into the ultrasonic container 191 for ultrasonic treatment, instead of being ultrasonically treated in the mixing container 11, thus avoiding the deterioration of the sealing performance of the mixing container 11 caused by ultrasonic treatment.

[0069] In some embodiments, the preparation system may further include a first feed line 1261 and a plurality of regulating valves 23. The first feed line 1261 may be used to provide fluid communication between the ultrasonic container 191 and the mixing body 112 of the mixing container 11. The plurality of regulating valves 23 may be disposed in the first feed line 1261 for controlling the on / off state of the first feed line 1261.

[0070] In some embodiments, the preparation system may further include a control device. The control device may be used to determine the operating parameters of the ultrasonic generator 192 based on the melting point of the metal nanoparticles and the temperature of the material in the ultrasonic container 191.

[0071] The embodiments of this application utilize a control device to determine the operating parameters of the ultrasonic generator 192, preventing the ultrasonic waves from causing a significant increase in fluid temperature, which could lead to the melting of nanoparticles and the formation of an alloy with sodium, thereby deteriorating the performance of the nanofluid. Simultaneously, it prevents the nanofluid from experiencing excessively high local temperatures, which could result in phenomena such as alkali metal boiling or flash evaporation, posing safety hazards.

[0072] In some embodiments, the operating parameters of the ultrasonic generator 192 may include the ultrasonic duration of the ultrasonic waves emitted by the ultrasonic generator 192 and the power of the ultrasonic generator 192. In some embodiments, the control device may set the ultrasonic duration to not exceed a preset duration to avoid phenomena such as alkali metal boiling or flash evaporation due to excessively high local temperatures of the nanofluid.

[0073] Typically, 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 based on the melting point of the metal nanoparticles and the temperature of the material in the ultrasonic container 191.

[0074] In some embodiments, the preparation system may further include a second feed line 1262 and a nanofluid storage container 21. The second feed line 1262 is used to provide fluid communication between the ultrasonic container 191 and the nanofluid storage container 21. The nanofluid storage container 21 is used to store the nanofluid obtained after ultrasonic treatment.

[0075] In some embodiments, the preparation system may further include a third feed line 1263 and a nanofluid transfer container 22. The third feed line 1263 is used to enable fluid communication between the nanofluid storage container 21 and the nanofluid transfer container 22. The nanofluid transfer container 22 is used to store the nanofluid to be transferred from the nanofluid storage container 21.

[0076] In some embodiments, the second conveying pipeline 1262 and the third conveying pipeline 1263 may also be provided with regulating valves 23, which are used to control the on / off state of the second conveying pipeline 1262 and the third conveying pipeline 1263, respectively.

[0077] Embodiments of this application also provide a method for preparing nanofluids, which involves mixing metal nanoparticles with an alkali metal to form a nanofluid. The preparation method uses the preparation system of any embodiment of this application to prepare the nanofluid.

[0078] In some embodiments, the preparation method includes steps S1 to S3.

[0079] S1. The metal nanoparticles are coated with solid alkali metal to form an integral part with the solid alkali metal.

[0080] S2. Add liquid alkali metal to the mixing container 11, add the integrated component to the sealed container 13, connect the discharge pipe 123 to the first feed pipe 121, and add the integrated component to the mixing container 11 through the discharge pipe 123 and the first feed pipe 121.

[0081] S3. Mix the integral component with liquid alkali metal to form a nanofluid.

[0082] In this embodiment, nanoparticles coated with a solid alkali metal to form a single component are placed in a sealed container 13 inside a glove box. The sealed container 13 and the discharge pipe 123 are then removed from the glove box, and the discharge pipe 123 is sealed to the first feed pipe 121, allowing the solid alkali metal-coated component to enter the mixing chamber 111 via the first feed pipe 121. During the process of the component entering the mixing chamber 111 via the discharge pipe 123 and the first feed pipe 121, it is beneficial to prevent the metal nanoparticles from adsorbing onto the inner wall of the mixing container 11 or the pipes, thereby avoiding inaccurate ratios of metal nanoparticles and alkali metal.

[0083] In some embodiments, step S1 includes: weighing a solid alkali metal (e.g., 20-30 g) and a target weight of metal nanoparticles in a glove box filled with inert gas under an inert atmosphere; heating the solid alkali metal into a liquid state; mixing the metal nanoparticles with the liquid alkali metal; and then pouring the liquid alkali metal containing the metal nanoparticles into a rod-shaped mold for cooling to obtain a monolithic component. After obtaining the monolithic component, it can be transferred to a sealed container 13 for sealed storage in a glove box filled with inert gas.

[0084] It is easy to understand that the total amount of solid alkali metal added in step S1 and liquid alkali metal added to mixing container 11 in step S2 is the content of alkali metal in nanofluid.

[0085] In some embodiments, the cross-sectional dimension of the integral part made in step S1 is smaller than the inner diameter of the discharge pipe 123 and the first feed pipe 121, and smaller than the through diameter of the first feed valve 128 and the second feed valve 129, so as to avoid the integral part from sticking to the pipe or valve and making it difficult to enter the mixing container 11 smoothly.

[0086] In some embodiments, in step S3, under atmospheric conditions, the sealed container 13 is connected to the first feed pipe 121 through the discharge pipe 123; the discharge pipe 123 and the first feed pipe 121 are evacuated, and then inert gas is injected into the discharge pipe 123 and the first feed pipe 121; the discharge pipe 123 and the first feed pipe 121 are connected, so that the integral part in the sealed container 13 enters the mixing container 11 through the discharge pipe 123 and the first feed pipe 121.

[0087] In some embodiments, step S3 includes: after the integral component is added to the mixing container 11, waiting for a first preset time to allow the alkali metal in the integral component to completely melt; then, using the agitator 151 to mechanically stir the material in the mixing container 11.

[0088] The method provided in the embodiments of this application waits for a first preset time to allow the alkali metal in the integral component to completely melt, and then uses the agitator 151 to mechanically stir the material in the mixing container 11. This avoids the agitator 151 throwing the integral component onto the inner wall of the mixing container 11 and adhering it to the inner wall before the alkali metal is completely melted, which would be detrimental to the full dispersion of metal nanoparticles in the liquid alkali metal.

[0089] In some embodiments, when the agitator 151 is started for the first time, the rotation speed of the agitator 151 should not be too high, for example, the rotation speed of the agitator 151 should be less than 100 rpm. If the rotation speed of the agitator 151 is relatively high, the metal nanoparticles will be more easily thrown onto the inner wall of the mixing chamber 111 during the stirring process.

[0090] In some embodiments, before the alkali metal is first filled into the alkali metal storage container 17, the alkali metal storage container 17 may be evacuated and filled with inert gas so that the water and oxygen content in the alkali metal storage container 17 does not exceed 50 ppm.

[0091] When using the agitator 151 to mechanically agitate the material in the mixing container 11, the drive unit 152 can be controlled to start the agitator 151 at a first speed and make the agitator 151 rotate at the first speed for a first preset time; then the agitator 151 can be made to rotate at a second speed for a second preset time, and then the agitator 151 can be made to rotate at a third speed for a third preset time; finally, the agitator 151 can be made to rotate 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 sequentially.

[0092] The method provided in the embodiments of this application controls the stirring element 151 to rotate at different speeds for different preset times, which is beneficial to enable the metal nanoparticles to be fully dispersed in liquid alkali metal.

[0093] In this embodiment, the material in the mixing container 11 can be mechanically stirred using the agitator 151 as follows: After the material enters the mixing chamber 111 and the alkali metal is fully melted (e.g., after 15 minutes), the drive unit 152 is controlled to start the agitator 151 at a speed of less than 100 rpm. After 3 minutes, the speed of the agitator 151 is increased to 100 rpm and kept stable for 15 minutes. After 15 minutes of stable operation, the speed of the agitator 151 is increased to 250 rpm and kept stable for 15 minutes. After another 15 minutes of stable operation, the speed of the agitator 151 is increased to 400 rpm and kept running for 12 minutes. During the above stirring process, the stirring temperature can be maintained in the range of 250-300°C.

[0094] In some embodiments, step S2 further includes: heating the liquid alkali metal in the alkali metal storage container 17 to a temperature range of 220-300°C; increasing the gas pressure in the alkali metal storage container 17 to inject a predetermined amount of liquid alkali metal from the alkali metal storage container 17 into the mixing container 11.

[0095] In some embodiments, step S3 further includes: ultrasonicating the mixed fluid to form a nanofluid.

[0096] In some embodiments, the frequency, duration, and power of ultrasonic treatment are determined based on the melting point of the metal nanoparticles and the temperature of the mixed fluid in the ultrasonic container 191. The embodiments of this application determine the frequency, duration, and power of ultrasonic treatment based on the melting point of the metal nanoparticles and the temperature of the mixed fluid in the ultrasonic container 191 to prevent the ultrasonic treatment from causing a significant increase in fluid temperature, which could lead to the melting of the nanoparticles and the formation of an alloy with sodium, thereby deteriorating the performance of the nanofluid. Simultaneously, it prevents the nanofluid from experiencing excessively high local temperatures, which could result in phenomena such as alkali metal boiling or flash evaporation, posing safety hazards.

[0097] 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 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 can be less than 3 minutes. For example, the ultrasonic frequency 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 ultrasonic waves generate a significant amount of heat. By setting the ultrasonic frequency to 19.5kHz and the power to 400W, the amount of heat generated by the ultrasonic waves can be relatively small, thereby keeping the temperature of the nanofluid lower. This prevents the metal nanoparticles from melting and forming an alloy with the liquid alkali metal, and also prevents the local temperature of the nanofluid from becoming too high, which could lead to boiling or flash evaporation of the alkali metal and pose safety hazards.

[0098] The preparation system and method of this application use mechanical stirring and ultrasonic treatment to uniformly disperse the nanoparticles added to the liquid alkali metal, resulting in a nanofluid with good uniformity.

[0099] The preparation system and method described in this application are applicable to the preparation of kilogram-scale sodium-based nanofluids.

[0100] The kilogram-scale sodium-based nanofluid preparation system and method described in this application can be used to conduct various performance tests on sodium-based nanofluids, such as suspension stability and thermal stability, thereby determining the impact of different preparation processes on the performance of sodium-based nanofluids. This provides validation data for the design of subsequent engineering-grade sodium-based nanofluid coolant preparation processes and systems.

[0101] The method for preparing nanofluids according to the embodiments of this application is described below with reference to specific examples.

[0102] (1) When the alkali metal storage container 17 is filled with sodium for the first time, the alkali metal storage container 17, the mixing container 11 and the ultrasonic container 191 and other related equipment and connecting pipes need to be purged with argon gas. When the content of water and oxygen impurities is less than 50 ppm, the sodium filling operation can be carried out.

[0103] (2) Heat the alkali metal in the alkali metal storage container 17 to 250°C.

[0104] (3) In the glove box, the target transition metal element nanoparticles and a small amount of solid sodium metal are weighed using a high-precision weighing method. After heating the solid sodium metal into a liquid, the nanoparticles are poured into the liquid sodium and mixed.

[0105] (4) The liquid sodium containing nanoparticles formed in step (3) is introduced into the mold and cooled to form a thin rod-shaped integral sample with a diameter of about 10 mm.

[0106] (5) Add the liquid sodium prepared in step (2) quantitatively into the mixing container 11.

[0107] (6) Put the prefabricated integral sample from step (4) into the sealed container 13.

[0108] (7) Install the sealed container 13 containing the integral sample from step (6) into the first feed line 121.

[0109] (8) Evacuate the pipeline between the sealed container 13 and the mixing container 11 by purging with argon gas. Repeat this process 4 times, then pressurize the pipeline to atmospheric pressure.

[0110] (9) Argon gas is introduced into the mixing container 11 so that the gas pressure in the mixing chamber 111 of the mixing container 11 is a slightly positive pressure, for example less than 3 kPa.

[0111] (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.

[0112] (11) Start the oil cooling system to cool down the magnetic sealing ring of the stirring assembly 15.

[0113] (12) After the integrated sample falls into the mixing container 11, wait for 15 minutes, then start the stirring component 151 at a low speed. After 3 minutes, increase the speed of the stirring component 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.

[0114] (13) Then stop stirring and use argon pressure to introduce the liquid sodium metal in the mixing container 11 into the ultrasonic container 191.

[0115] (14) The nanoparticles in the basic sodium solution were dispersed for 30 minutes using an ultrasonic generator with an ultrasonic frequency of 19.5 kHz and a power of 400 W.

[0116] (15) The sodium-based nanofluid dispersed by ultrasonication in step (14) is transferred to the nanofluid storage container 21 again by argon gas to complete the preparation of sodium-based nanofluid.

[0117] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0118] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A nanofluid preparation system for mixing metal nanoparticles with an alkali metal to form a nanofluid, characterized by, The preparation system comprises: a mixing container configured to form a mixing cavity; a first feeding pipe for feeding metal nanoparticles into the mixing cavity; a second feeding pipe for feeding liquid alkali metal into the mixing cavity; a sealed container configured to form a sealed cavity for containing the metal nanoparticles, wherein the metal nanoparticles are coated by solid alkali metal to form an integral piece with the solid alkali metal; a discharge pipe connected to the sealed container, the discharge pipe is configured to be detachably connected to the first feeding pipe, and when the discharge pipe is detached from the first feeding pipe, the sealed cavity and the mixing cavity can be sealed respectively; when the discharge pipe is connected to the first feeding pipe, the sealed cavity can be in communication with the mixing cavity, so that the integral piece in the sealed container can enter the mixing cavity through the discharge pipe and the first feeding pipe in sequence.

2. The preparation system according to claim 1, characterized in that, Further comprising: a first feeding valve arranged in the first feeding pipe; a second feeding valve arranged in the discharge pipe; a first vacuum and gas filling pipe connected to the first feeding pipe or the discharge pipe, so that the pipe between the first feeding valve and the second feeding valve can be vacuumed and filled with inert gas when the discharge pipe is connected to the first feeding pipe.

3. The preparation system of claim 1, wherein, Further comprising: a stirring assembly arranged in the mixing container for mechanically stirring the material in the mixing cavity.

4. The preparation system according to claim 3, characterized in that The mixing container comprises a stirring through hole; The stirring assembly comprises: a stirring piece entering the mixing container from the stirring through hole; a driving piece arranged outside the mixing container for driving the stirring piece to rotate; a magnetic force sealing piece arranged outside the mixing container for sealing between the stirring piece and the stirring through hole of the mixing container.

5. The preparation system according to claim 4, characterized in that Further comprising: a cooling piece for cooling the magnetic force sealing piece.

6. The system for producing according to claim 1, characterized in that, Further comprising: an alkali metal storage container for providing liquid alkali metal; a second vacuum and gas filling pipe for vacuuming and filling the alkali metal storage container with inert gas to drive the liquid alkali metal from the alkali metal storage container to the mixing container through the second feeding pipe by gas pressure.

7. The production system according to claim 6, characterized in that Further comprising: a weighing device for weighing the alkali metal storage container and / or the mixing container to facilitate determining the weight of the liquid alkali metal entering the mixing container.

8. The production system of claim 1, wherein, Further comprising: an ultrasonic device for receiving material from the mixing container to perform ultrasonic treatment on the material.

9. The production system according to claim 8, characterized in that The ultrasonic device comprises: an ultrasonic container in fluid communication with the mixing container; an ultrasonic generating piece arranged in the ultrasonic container for performing ultrasonic treatment on the material in the ultrasonic container.

10. A method for preparing a nanofluid for mixing metal nanoparticles with an alkali metal to form a nanofluid, characterized by, The preparation method uses the preparation system of any one of claims 1-9 to prepare the nanofluid.

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