Spliceable low-temperature and low-humidity visual sealing liquid drop impact experiment device

Abstract

This invention discloses a modular, low-temperature, low-humidity, visually sealed droplet impact experimental apparatus, comprising an environmental cooling and dehumidification device for dehumidifying the sealed chamber and cooling the substrate placed inside. The environmental cooling and dehumidification device includes a substrate treatment system for treating droplet residues after each impact. Above the substrate treatment system is a droplet control and generation device for stably generating droplets and controlling their impact velocity and temperature. A data acquisition system and an auxiliary system are located on one side of the substrate treatment system. The data acquisition system monitors and collects experimental data obtained by the substrate treatment system, while the auxiliary system provides a light source for the data acquisition system. This invention improves experimental efficiency, reduces time and economic costs, and meets the need for obtaining substrates with greater supercooling at a lower temperature with minimal time cost.

Description

Technical Field

[0001] This invention belongs to the field of droplet impact experiment technology, specifically relating to a modular, low-temperature, low-humidity, visible, sealed droplet impact experiment device. Background Technology

[0002] The solidification problem of droplets impacting cold substrates is widespread in nature and in daily life, such as freezing rain and droplet 3D printing. Exploring the underlying physical mechanisms of these phenomena involves not only droplet impact dynamics but also complex thermodynamic heat transfer processes, classifying them as complex multiphase flow problems. A more in-depth understanding of these issues requires an efficient, precise, and stable experimental setup for droplet impact on low-temperature substrates.

[0003] Currently, experimental setups for studying droplet impacts on cold substrates typically involve placing the droplet generator and the substrate in two separate, transparent, sealed enclosures. The target aperture is then opened when impact is required. However, this type of setup has several drawbacks:

[0004] 1) Since the droplets solidify upon impact with the low-temperature substrate, the target substrate needs to be replaced for the next experiment. This requires opening the sealed experimental chamber, which will cause significant condensation and frost formation because the target substrate remains at a low temperature. Alternatively, the target substrate can be replaced after it has warmed up. Both of these methods not only reduce experimental efficiency and increase the use of protective gas, but also significantly increase costs.

[0005] 2) The adjustment of droplet impact velocity is mostly achieved by manually adjusting the droplet height using a linear guide rail, which has poor effectiveness and accuracy.

[0006] 3) Obtaining supercooled droplets or low-temperature substrates, whose temperatures are often lower than the local air dew point and frosting temperature, will lead to severe condensation and frosting, affecting the rigor of the experiment.

[0007] 4) Substrate cooling mostly uses semiconductor cooling. Since semiconductor cooling is highly dependent on the ambient temperature, the substrate temperature that can be achieved is often limited.

[0008] Currently, the main experimental setup for this research typically involves placing the substrate, where droplets collide and at low temperatures, within a transparent, sealed container, such as an acrylic or tempered glass enclosure. Most cryogenic sealing experiments are conducted in such enclosures, but this has also led to numerous problems.

[0009] 1) Existing solutions generally place the droplet generator and the substrate cooling device in two separate sealed chambers. The main purpose of this is to facilitate manual adjustment of the needle position to change the droplet impact velocity. However, this solution causes changes in the humidity of the chamber when it is opened during the impact process, affecting the accuracy of the experiment. Secondly, manually adjusting the droplet impact height also introduces human error. Some solutions place the needle and the low-temperature substrate in the same chamber, but this solution makes it difficult to adjust the droplet impact height. Furthermore, the overall height design of the chamber will change with the impact height experimental parameters, resulting in poor versatility and high economic cost. Moreover, the process of opening and closing the chamber and changing the low-temperature substrate causes condensation and frost to form on the needle cooling device, increasing the complexity of the experiment.

[0010] 2) All experimental protocols in this study currently involve substrate replacement. Moreover, the frequent opening and closing of the chamber during substrate replacement exacerbates the condensation and frost problems, leading to more additional experimental operations, significantly increasing experimental time and economic costs, and reducing experimental accuracy.

[0011] 3) Since the experimental data acquisition system primarily relies on high-speed cameras, which occupy considerable space after lens installation, current technical solutions often place the camera outside the sealed enclosure. Because these transparent sealed enclosures are mostly made of transparent acrylic or tempered glass, due to manufacturing processes, their light transmittance is not uniform within the camera lens's field of view. Therefore, even when the camera lens is perpendicular to the transparent wall to capture the impact process, refractive errors still occur. When the camera needs to be tilted to capture the impact point, the refraction caused by the transparent wall becomes even more severe. We have verified this issue ourselves, and it can also be found in many published scientific papers.

[0012] 4) Since condensation and frost on the low-temperature substrate surface have a serious impact on the curing mechanism investigated in the experiment, it is necessary to dehumidify the low-temperature substrate environment and the environment where the supercooled droplets are located before conducting the experiment. Generally, dry nitrogen gas is introduced into the chamber for initial protection, and desiccant is added into the chamber for auxiliary dehumidification.

[0013] According to the scheme described in 1), the former opens some holes during impact, which changes the humidity inside the chamber. Some studies have also chosen to continuously introduce nitrogen to avoid this problem. This not only increases the amount of nitrogen used, but also changes the airflow state of the environment at the impact point. The latter adopts a needle-base integrated chamber design. Due to the large volume of the chamber and the need for frequent opening and closing of the chamber for experiments, the amount of nitrogen used will increase significantly, and the economic cost will increase significantly. Summary of the Invention

[0014] The technical problem to be solved by the present invention is to provide a splicable low-temperature and low-humidity visible sealed droplet impact experimental device to address the shortcomings of the prior art. This device solves the technical problems of existing low-temperature droplet impact substrate experimental devices in terms of droplet impact velocity variation, condensation and frost prevention, substrate replacement, and high consumption of dehumidification gas.

[0015] The present invention adopts the following technical solution:

[0016] A modular, low-temperature, low-humidity, visually sealed droplet impact experimental apparatus includes an environmental cooling and dehumidification device for dehumidifying the sealed chamber and cooling the substrate placed inside. The environmental cooling and dehumidification device houses a substrate treatment system for treating droplet residues after each impact. Above the substrate treatment system is a droplet control and generation device for stably generating droplets and controlling their impact velocity and temperature. A data acquisition system and an auxiliary system are located on one side of the substrate treatment system. The data acquisition system monitors and collects experimental data from the substrate treatment system, while the auxiliary system provides a light source for the data acquisition system.

[0017] Specifically, the environmental cooling and dehumidification device includes an atmospheric pressure nitrogen tank, which is connected to a sealed enclosure and a substrate treatment system placed inside the sealed enclosure. The substrate treatment system is connected to the liquid nitrogen tank via a flow control valve.

[0018] Furthermore, a pressure reducing valve and a pressure gauge are installed on the connecting pipeline between the atmospheric pressure nitrogen tank and the sealed enclosure, and a chamber pressure monitoring pressure gauge assembly for monitoring and regulating the internal air pressure of the sealed enclosure is installed on the top of the sealed enclosure.

[0019] Specifically, the droplet control and generation device includes a stainless steel needle installed inside the sealed chamber. The stainless steel needle is connected to a syringe installed outside the sealed chamber via a pipeline. One end of the syringe is connected to a micro-injection pump. The stainless steel needle is surrounded by a circulating cooling head, which is connected to a circulating refrigeration unit installed outside the sealed chamber via a circulation pipeline.

[0020] Furthermore, the circulating cooling head is fixed on the linear motor guide rail, which is electrically connected to the linear motor control module outside the sealed housing.

[0021] Specifically, the substrate processing system includes a copper vessel placed inside a sealed box, with the substrate placed inside the copper vessel. A robotic arm is installed on one side of the copper vessel, and the robotic arm is connected to an Arduino control module and a vacuum pump installed outside the sealed box.

[0022] Furthermore, the bronze vessel consists of a lower layer, a middle layer, and an upper layer from bottom to top, with a porous medium plate installed in the middle layer.

[0023] Furthermore, the robotic arm includes a base, on which a wrist is mounted. The wrist is connected to the forearm via the upper arm. Servo motors are mounted between the wrist and the base, between the wrist and the upper arm, and between the upper arm and the forearm. The forearm includes a hand structure made of a porous screen and a vacuum suction cup. The hand structure is used to process particulate substrates, and the vacuum suction cup is connected to a vacuum pump via a hose.

[0024] Specifically, the data acquisition system includes a first point temperature thermocouple and a humidity detector installed at the base processing system, a second point temperature thermocouple installed at the droplet control and generation device, and a high-speed camera installed on one side of the sealed enclosure. The first point temperature thermocouple, the second point temperature thermocouple, and the humidity detector are connected to the computer via a temperature and humidity acquisition device installed outside the sealed enclosure. The computer is connected to the high-speed camera.

[0025] Specifically, the auxiliary system includes a controller, which is connected to an LED fiber optic lamp on one side of the substrate treatment system inside the sealed enclosure.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] A modular, low-temperature, low-humidity, visually sealed droplet impact experimental device is provided. The environmental cooling and dehumidification device is used to ensure that the moisture in the internal environment of the chamber will not condense or frost during the subsequent cooling of the substrate and droplets, thus ensuring experimental accuracy; it also accelerates the cooling of the substrate and makes the cooling of the substrate more uniform. A circulating chiller is connected to a circulating cooling head inside the chamber via a circulating pipeline to cool the droplets used in the experiment. A substrate treatment system is connected to a liquid nitrogen pipeline for rapid cooling of the experimental substrate. An image and data acquisition system monitors and acquires data from the experimental apparatus, making the obtained experimental data more accurate and providing a reliable basis for subsequent experimental data analysis. Other auxiliary systems support experimental data acquisition and the preparation of other experimental parameters, enriching the range of experimental parameters, increasing the amount of data acquired, improving experimental accuracy, and enhancing the applicability of the invention. Since all relevant experimental parameters are controlled semi-automatically outside the sealed chamber, only one dehumidification cycle is needed to perform multiple experimental operations without opening the chamber, significantly reducing the amount of nitrogen used for dehumidification and saving considerable costs. The experiment and parameter preparation, which originally required opening the chamber and performing them inside, are now controlled by external devices without opening the chamber, greatly improving experimental efficiency and accuracy while saving costs.

[0028] Furthermore, the externally pressurized liquid nitrogen tank is connected to the copper vessel containing the substrate inside the sealed box via an insulated corrugated pipe and a pipe connection point within the box. Since the volume of liquid nitrogen vaporized each time in the entire pipeline connecting the liquid nitrogen tank and the copper vessel is not the same, this will cause the gas pressure in the pipeline to change with the vaporization of liquid nitrogen, affecting the cooling rate of the substrate target. A pressure gauge is installed on the pipeline to monitor the pipeline pressure, ensuring that the pressure in the pipeline remains within a safe and stable range, allowing the cold airflow in the pipeline to safely and stably cool the target substrate. At the same time, a pressure reducing valve is installed on the pipeline to release pressure when the pressure in the pipeline exceeds the safe range, ensuring the safety of the entire experimental system.

[0029] Furthermore, a pressure reducing valve and a pressure gauge are installed on the connecting pipeline between the atmospheric pressure nitrogen tank and the sealed chamber. The pressure gauge is used to monitor the pressure value of this gas path, and the pressure value reflects the gas flow rate in the gas path. According to the volume of the assembled chamber and the required dehumidification rate, the airflow rate in this gas path is stabilized and controlled by adjusting the pressure reducing valve. Since both the dehumidifying gas and the cooling gas will enter the sealed chamber, the pressure inside the sealed chamber will rise when the target humidity and target temperature are not reached. Therefore, a chamber pressure monitoring pressure gauge assembly is installed on the top of the sealed chamber to monitor and regulate the internal pressure, ensuring that the internal pressure of the chamber remains stable within a certain range throughout the experiment, and ensuring that the experimental results are not affected by other factors.

[0030] Furthermore, a stainless steel needle housed inside the sealed chamber is connected to a syringe located outside the chamber via tubing. One end of the syringe is connected to a micro-injection pump, which generates uniformly sized droplets, ensuring consistent droplet size throughout the experiment and preventing any impact from inconsistent droplet size. A circulating cooling head surrounds the stainless steel needle, connected to a circulating refrigerator outside the chamber via tubing. Refrigerant from the refrigerator enters the cooling head through the tubing, exchanging heat with the liquid inside the needle. This maintains the droplets below the needle at the target temperature set in the experiment. The circulating cooling head surrounding the needle increases its heat exchange efficiency, ensuring stable droplet temperature throughout the experiment and guaranteeing experimental accuracy. Simultaneously, the circulating cooling head and the stainless steel needle are flexibly connected, ensuring that the heat exchange efficiency remains stable even when the needle height is subsequently changed.

[0031] Furthermore, since the impact velocity of the droplets is a crucial experimental parameter in this type of droplet impact experiment, the circulating cooling head is fixed to a linear motor guide rail. This guide rail is electrically connected to a linear motor control module outside the sealed chamber. By adjusting the parameters of the linear motor control module, the displacement module on the linear motor guide rail can move the circulating cooling head and stainless steel needle up and down without opening the sealed test chamber, thus in accordance with the laws of free fall. The droplet impact velocity is adjusted. The entire process of adjusting the droplet impact velocity not only ensures that the temperature, humidity, and pressure conditions inside the sealed chamber remain unchanged, but also avoids errors in droplet impact velocity caused by human operation, making the experiment more efficient, economical, and accurate.

[0032] Furthermore, the primary purpose of the Little-arm robotic arm is to handle the residual substrate after impact solidification and to prepare new experimental substrates. It allows for control of the robotic arm's movement inside the enclosure from outside the enclosure, handling and updating the experimental substrate. Compared to three-degree-of-freedom robotic arms on the market, its biggest advantage is its simple structure and small size, which not only increases experimental efficiency and saves space in the experimental enclosure but also significantly reduces experimental costs. The introduction of the robotic arm eliminates the need for manual operation to open the enclosure and replace the substrate, avoiding the complexities associated with opening the enclosure. The issues arising from opening the enclosure have been detailed previously and will not be repeated here. The robotic arm's control system is implemented using an Arduino control module. Meanwhile, to adapt to different impact substrate targets, the mechanical head adopts two structures: a screen hand and a vacuum suction cup hand. The screen hand is used to clean and transport granular target substrates, while the vacuum suction cup hand works in conjunction with a vacuum pump to generate negative pressure at the suction cup head for transporting solid target substrates. This increases the experimenter's ability to transport different targets while ensuring the efficiency of transporting residual substrates and preparing new substrates (contact the inventor to watch a video of the robotic arm performing the transport operation).

[0033] Furthermore, since the gas path and refrigeration pipeline are connected to the horizontal threaded joint at the bottom of the copper vessel via a corrugated pipe, when the gas flows through the lower layer of the copper vessel, the porous dielectric plate restricts the incoming gas from entering the middle and upper layers. This allows the incoming gas to uniformly fill the lower layer of the copper vessel and form a small positive pressure cavity in this part. As a result, the single stream of gas entering the lower layer through the joint can stably enter the middle and upper layers of the copper vessel after flowing through the lower layer and being buffered by the porous dielectric plate. This ensures that the gas flow velocity through the target substrate is stable and controllable, and guarantees the safety of the experimental target substrate.

[0034] Furthermore, the entire robotic arm structure strives for simplicity and compactness. During the design process, the functional objective of transporting waste substrates and preparing new ones was prioritized, with a focus on streamlining the mechanical structure and dimensions. The structural design retains only the basic structure of a three-degree-of-freedom robotic arm. Since the substrate targets for droplet impacts are generally relatively small in mass, the MG996R servo motor was selected, capable of safely bearing a weight of 2KG with all arm lengths extended. The entire robotic arm occupies a three-dimensional space of 10CM × 13CM × 17CM, fully meeting the operational objectives while maintaining a streamlined structure. Simultaneously, the hand employs a dual-structure design, suitable for both granular and solid substrates, satisfying the needs of different experimenters.

[0035] Furthermore, point thermocouples can accurately reflect the target temperature and record the temperature of key components in the experiment. Simultaneously, a humidity detector monitors the humidity inside the chamber, providing internal humidity data to support subsequent experimental analysis. This ensures the entire experiment is conducted under uniformly set target parameters, guaranteeing its reliability. A high-speed camera connects to the computer to acquire experimental data in real time, providing high-frame-rate image data.

[0036] Furthermore, an LED fiber optic lamp is placed on one side of the substrate processing system inside the sealed enclosure. High frame rate shooting often requires a strong background light source. The adjustable intensity LED fiber optic lamp can not only meet the lighting requirements of shooting at different frame rates, but also provide high-quality image data for subsequent image processing, reducing the complexity of programming in the process of processing image data and reducing the time consumed by data processing.

[0037] In summary, this invention employs a modular box structure, making the box height simple and controllable. Combined with a room-temperature nitrogen gas path, liquid nitrogen cooling pipeline, and copper containers, it cools the impact target substrate, ensuring the acquisition of an ultra-low temperature substrate. This also saves on experimental consumables, reduces experimental costs, increases experimental accuracy, and ensures personnel safety. The use of a linear guide control module, a robotic arm control module, a circulating cooling system, and a micro-injection system allows the experimental device to transport waste substrates and replace them with new target substrates via a semi-automated three-degree-of-freedom robotic arm without opening the sealed box. The linear guide external control device automatically adjusts the droplet impact velocity; the circulating refrigerant and cooling head work together to ensure precise and controllable droplet temperature; and the micro-injection system... The external ejector pump pushes the syringe to produce uniformly sized experimental droplets, greatly improving experimental efficiency and reducing the consumption of additional experimental consumables due to frequent opening of the chamber, thus lowering costs. It also increases experimental reliability and reduces unnecessary complications in subsequent data analysis. Through the cooperation of point thermocouples, humidity probes, pressure reducing valves, and pressure gauges, the experimental process is quantified, providing data support for experimental credibility and ensuring experimental safety by preventing safety issues caused by overcooling (liquid nitrogen overflow) or overpressure, thus ensuring the safety of experimental personnel. By cooperating with auxiliary system light sources and other data acquisition systems such as high-speed cameras, the droplet impact and solidification process is captured, providing high-quality experimental data for subsequent experimental phenomenon analysis and reducing the time cost of experimental data processing.

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the experimental apparatus of the present invention;

[0040] Figure 2 This is a cross-sectional view of a bronze vessel.

[0041] Figure 3 This is a schematic diagram of the robotic arm structure.

[0042] The components include: 11. Atmospheric pressure nitrogen tank; 12. Pressure reducing valve; 13. Sealed enclosure; 14. Flow control valve; 15. Liquid nitrogen tank; 16. Circulating refrigeration unit; 17. Enclosure pressure monitoring gauge assembly; 21. Linear motor control module; 22. Linear motor guide rail; 23. Stainless steel needle; 24. Circulating refrigeration head; 25. Syringe; 26. Micro-injection pump; 31. Arduino control module; 32. Robotic arm; 321. Forearm. 322. Upper arm; 323. Wrist; 324. Base; 33. Copper vessel; 331. Upper layer; 332. Porous dielectric plate; 333. Middle layer; 334. Bolt; 335. Lower layer; 34. Vacuum pump; 41. First-point temperature thermocouple; 42. Second-point temperature thermocouple; 43. Humidity detector; 44. High-speed camera; 45. Computer; 46. Temperature and humidity sensor; 51. Controller; 52. LED fiber optic lamp. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," and "one side," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0047] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0048] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0049] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0050] This invention provides a modular, low-temperature, low-humidity, visually controlled sealed droplet impact experimental device. It allows for the replacement of the target substrate using a semi-automatic three-degree-of-freedom robotic arm without opening the sealed chamber, and semi-automatic adjustment of the droplet impact velocity via external control equipment. Furthermore, the sealed chamber employs a modular flange structure for assembly, allowing for chamber additions to the base chamber and adjustment according to the maximum height required for the experiment. The device offers advantages such as convenient parameter adjustment, a wide adjustable range of parameters, practical experimental chamber design, low cost, stable parameter control, high accuracy, and high efficiency.

[0051] Please see Figure 1 The present invention discloses a modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device, comprising an environmental cooling and dehumidification device, a droplet control and generation device, a substrate treatment system, a data acquisition system, and an auxiliary system; the substrate treatment system is disposed within the sealed housing 13 of the environmental cooling and dehumidification device, the droplet control and generation device is disposed above the substrate treatment system, and the data acquisition system and the auxiliary system are disposed on one side of the substrate treatment system.

[0052] The environmental cooling and dehumidification device includes a liquid nitrogen tank 15 (liquid nitrogen storage) and delivery pipeline (external pressurization), a circulating refrigerator 16, a sealed experimental chamber 13, an atmospheric pressure nitrogen tank 11 (nitrogen storage) and delivery device.

[0053] The atmospheric pressure nitrogen tank 11 is connected to the sealed box 13 and the copper vessel 33 placed inside the sealed box 13 via the pressure reducing valve 12 and the pressure gauge, respectively. The copper vessel 33 is connected to the liquid nitrogen tank 15 with a booster via the flow control valve 14. The atmospheric pressure nitrogen tank 11 can dehumidify the inside of the sealed box 13 through the pipeline connected to the sealed box 13. On the other hand, it can prepare the required deposition fraction of the substrate through the pipeline connected to the copper vessel 33 and accelerate the flow of cold air during the cooling process, so as to achieve the problem of the low temperature substrate dropping to the target temperature more quickly.

[0054] The liquid nitrogen tank 15 is connected to the copper vessel 33 via its built-in booster and flow control valve 14 (the connecting pipeline is insulated to reduce frost and liquid nitrogen loss in the liquid nitrogen tank exposed to room temperature). It is used to cool the substrate. Low temperature is one of the main core objectives of this invention. The liquid nitrogen is connected to the copper vessel 33 via the flow control valve 14 to achieve stable control of the substrate temperature. Compared with other cooling methods, liquid nitrogen can reduce the target temperature by -120°C (which has been verified in experiments), or even lower, and can cool the target substrate to -196°C.

[0055] To ensure control of the gas flow rate in the gas path, a pressure reducing valve 12 and a pressure gauge are installed throughout the gas path to monitor and adjust the gas pressure. The gas flowing out of the atmospheric pressure nitrogen tank 11 enters the sealed chamber 13 through the gas path to dehumidify the internal environment of the experimental chamber, so as to ensure that the moisture in the internal environment of the chamber will not condense or frost during the subsequent cooling of the substrate and droplets, thus ensuring experimental accuracy. The gas flowing out of the atmospheric pressure nitrogen tank 11 enters the copper vessel 33 in the sealed chamber 13 where the substrate is placed through the gas path to accelerate the cooling of the substrate and make the cooling of the substrate more uniform.

[0056] The top of the sealed chamber 13 is equipped with a chamber pressure monitoring pressure gauge assembly 17, which can monitor the air pressure inside the sealed chamber 13 and adjust the internal air pressure of the sealed chamber 13 at any time to keep the experiment under the same air pressure conditions.

[0057] The sealed enclosure 13 is the main body of the experimental apparatus of this invention, used to provide a stable environment for droplet impact on a low-temperature substrate, increasing the accuracy of the experiment. The upper part of the sealed enclosure 13 features a modular flange sealing structure, solving the problem of different conditions in different experiments. The purpose of the requirement is to achieve the desired droplet impact velocity.

[0058] The circulating chiller 16 is used to cool the stainless steel needle 23 of the droplet control and generation device, so that the droplet temperature can be stably controlled when performing droplet impact experiments on the experimental apparatus of the present invention.

[0059] The circulating chiller 16 is connected to the circulating cooling head inside the sealed box 13 through a circulating pipeline. Its main purpose is to cool down the droplets used in the experiment and accelerate the solidification process of the droplet impact.

[0060] In this invention, since all relevant experimental parameters are controlled by semi-automatic control outside the sealed chamber 13, multiple experiments can be conducted without opening the chamber after only one dehumidification, which greatly reduces the amount of nitrogen used for dehumidification and saves a lot of costs.

[0061] The droplet control and generation device includes a syringe 25, a circulating cooling head 24, a linear motor guide rail 22, and a linear motor control module 21.

[0062] One end of the syringe 25 is connected to the micro-injection pump 26, and the other end is connected to the stainless steel needle 23 inside the sealed housing 13 through a thin tube. The circulating cooling head 24 surrounds the stainless steel needle 23 and is connected to the circulating cooling machine 16 through a circulation pipeline. By operating the micro-injection pump 26 outside the sealed housing 13, a stable droplet is generated at the outlet of the stainless steel needle 23 by the syringe 25 and surrounded by the circulating cooling head 24. After setting the parameters of the circulating cooling machine 16, the circulating liquid enters the circulating cooling head 24 through the circulation pipeline to cool the circulating cooling head 24. After the second point temperature thermocouple 42 inside the circulating cooling head 24 collects a stable temperature, the temperature of the droplet suspended below the stainless steel needle 23 is determined through a preliminary calibration experiment.

[0063] The micro-injection pump 26 is connected to the stainless steel needle 23 inside the sealed chamber 13 via tubing to precisely generate droplets of the required size for the experiment. Meanwhile, the stainless steel needle 23 inside the sealed chamber 13 is wrapped and fixed on the linear motor guide rail 22 inside the sealed chamber 13 by the circulating cooling head 24 (connected to the circulating cooling machine outside the chamber to reduce the droplet temperature). The droplet impact speed is changed by the linear motor control module 21 outside the sealed chamber 13. Compared with the existing manual adjustment of the droplet falling height, the semi-automatic control of the droplet falling height not only increases the experimental accuracy but is also very convenient.

[0064] The linear motor control module 21, linear motor guide rail 22, stainless steel needle 23, and circulating cooling head 24 work together to control the droplet impact speed. The main functions of the linear motor control module 21 and linear motor guide rail 22 are to stably generate droplets and control the droplet impact speed and droplet temperature. The linear motor guide rail 22 is fixed inside the sealed box 13 and connected to the linear motor control module 21 outside the sealed box 13. The stainless steel needle 23 and circulating cooling head 24 are fixed together on the slider on the linear motor guide rail 22. The linear motor control module 21 is operated from outside the sealed box 13 to adjust the height of the slider on the linear motor guide rail 22, thereby controlling the height between the stainless steel needle 23 and the copper vessel 33 on which the substrate is placed. In this way, the experimental purpose of changing the droplet impact speed is achieved by changing the droplet falling height.

[0065] The substrate processing system can process the droplet residue after each impact and replace it to prepare a new substrate, including an Arduino control module 31, a robotic arm 32, a copper vessel 33, and a vacuum pump 34.

[0066] A copper vessel 33 is placed inside a sealed box 13. A robotic arm 32 is positioned on one side of the copper vessel 33 and is connected to an Arduino control module 31 and a vacuum pump 34 outside the sealed box 13, respectively. The robotic arm 32 inside the sealed box 13 is controlled by the Arduino control module 31 outside the sealed box 13, so that after each droplet impact experiment, the residue solidified by the droplet impact can be removed and a new substrate required for the next impact can be prepared without opening the sealed box 13.

[0067] The copper vessel 33 is connected to the liquid nitrogen pipeline to cool the substrate. The robotic arm 32 is used to transport the residual substrate after impact solidification and to prepare a new substrate. The control part of the robotic arm 32 is provided by the Arduino control module 31, which enables the robotic arm 32 to move, transport and update the substrate from outside the sealed box 13. At the same time, compared with the three-degree-of-freedom robotic arms on the market, the biggest advantage of the robotic arm 32 is its simple structure and small size, which not only increases the experimental efficiency, saves the experimental box space, and greatly reduces the experimental cost, but also has a simple structure.

[0068] Please see Figure 2 The copper vessel 33 consists of a lower layer 335, a middle layer 333, and an upper layer 331 from bottom to top. The two ends of the porous medium plate 332 are connected to the middle layer 333 by bolts 334. The lower layer 335 is connected to the liquid nitrogen pipeline. The internal cavity is a buffer zone. When the liquid nitrogen tank 15 is pressurized by the pressurizer, the liquid nitrogen delivery rate is increased. The lower layer 335 is used to store liquid nitrogen and temperature feedback is provided by a temperature thermocouple to further control the liquid nitrogen flow rate and prevent liquid nitrogen from overflowing.

[0069] The porous medium plate 332 is used to buffer the cold nitrogen gas flowing out from the liquid nitrogen pipeline. Due to the vaporization of liquid nitrogen in the liquid nitrogen tank 15 and the liquid nitrogen pipeline, the internal pressure of the pipeline temporarily increases. The buffering of the porous medium plate 332 makes the airflow reaching the upper layer 331 relatively stable, making the cooling of the substrate more stable and preventing the substrate target from being blown over.

[0070] The robotic arm 32 is used to process the substrate and prepare new substrates in a timely manner. Due to the limited experimental space, the three-degree-of-freedom robotic arms available on the market are relatively large. Although they can complete the experimental purpose of processing waste substrates and preparing new substrates, they will greatly increase the volume of the sealed box and increase the experimental cost. Therefore, in order to reduce costs and achieve the experimental purpose, this invention designs a small robotic arm specifically for replacing the substrate that has been solidified by droplet impact.

[0071] Please see Figure 3 The robotic arm 32 includes a base 324, a wrist 323, an upper arm 322, a lower arm 321, and three servo motors. It is controlled by an Arduino control module 31. One end of the wrist 323 is fixed to the base 324, and the other end of the wrist 323 is connected to the lower arm 321 through the upper arm 322. The three servo motors are respectively located between the wrist 323 and the base 324, between the wrist 323 and the upper arm 322, and between the upper arm 322 and the lower arm 321. The lower arm 321 consists of two parts: one part is a hand structure made of a porous screen, which is used to process particulate substrates; the other part is a vacuum suction cup, which is connected to a vacuum pump 34 located outside the sealed housing 13 through a hose. The vacuum suction cup is used to process substrates.

[0072] The data acquisition system is used to record the temperature and humidity data inside the sealed chamber 13 and feed it back to the environmental cooling and dehumidification device, so as to jointly stabilize and control the temperature and humidity inside the sealed chamber 13 as well as the temperature of the droplets and the substrate, increase the experimental accuracy, and collect the droplet impact dynamics process.

[0073] The data acquisition system includes a first-point temperature thermocouple 41, a second-point temperature thermocouple 42, a humidity detector 43, a high-speed camera 44, a computer 45, and a temperature and humidity acquisition device 46.

[0074] The first point temperature thermocouple 41 is installed at the copper vessel 33 to collect data from the substrate. The second point temperature thermocouple 42 is installed at the circulating cooling head 24 to collect the temperature data of the droplets inside the circulating cooling head. The humidity detector 43 is installed inside the sealed box 13. The first point temperature thermocouple 41, the second point temperature thermocouple 42 and the humidity detector 43 are respectively connected to the temperature and humidity collector 46 installed outside the sealed box 13. The temperature and humidity collector 46 is used to collect and store the humidity and temperature data inside the sealed box 13.

[0075] A high-speed camera 44 is installed on the outside of the sealed enclosure 13 to record captured image data and transmit it to the computer 45. The camera records the process of droplet impact and solidification on a cold substrate. The stable environment inside the sealed enclosure 13 provides a reliable recording environment for the droplet impact and solidification process, making the obtained image data more accurate.

[0076] The data acquisition system is used to monitor and collect data from the experimental apparatus of this invention, making the obtained experimental data more accurate and providing a reliable basis for subsequent experimental data analysis.

[0077] The auxiliary system includes a controller 51 and an LED fiber optic lamp 52. The LED fiber optic lamp 52 is located on one side of the copper vessel 33 inside the sealed enclosure 13 and is connected to the controller 51 outside the sealed enclosure 13. It is used to provide a light source for the high-speed camera 44, making the image data near the impact point more clear and reliable.

[0078] The auxiliary system is used to support the acquisition of experimental data and the preparation of other experimental parameters. For example, in this invention, a laser system is added to measure the deformation data of the experimental target; an electromagnetic hammer is used to change the experimental parameters of the particle accumulation, etc. This not only enriches the range of experimental parameters, but also increases the amount of data obtained, increases the experimental accuracy, and also increases the applicability of this invention.

[0079] The working method of the modular, low-temperature, low-humidity, visually sealed droplet impact experimental device of the present invention is as follows:

[0080] Before conducting the experiment, calibrate the height between the stainless steel needle 23 and the copper vessel 33 inside the sealed chamber 13, confirm the initial position (impact velocity) of the droplet injected by the syringe 25, and place the experimental target substrate in the copper vessel 33. The temperature and humidity inside the sealed chamber 13 and the relevant experimental target are confirmed by the temperature and humidity acquisition device 46 in the data acquisition system 4. After completing the preparation work, close the working window opened in the sealed chamber 13.

[0081] Open the atmospheric pressure nitrogen cylinder 11 of the environmental cooling and dehumidification device, and adjust the pressure reducing valve 12 to introduce nitrogen into the sealed box 13. Observe the temperature and humidity data of the temperature and humidity acquisition device 46. When the humidity conditions required by the experimental target are reached, adjust the pressure reducing valve 12 to stabilize the humidity data inside the sealed box 13. Currently, in the experiment of this invention, the relative humidity inside the sealed box 13 can be reduced to (5% HR).

[0082] Because the ambient humidity will condense and frost on the surface of low-temperature components under low-temperature conditions, the dehumidification operation inside the sealed box 13 must be carried out before cooling. After the humidity inside the sealed box 13 is stable, open the pressurizer valve and flow control valve 14 of the liquid nitrogen tank 15, and at the same time turn on the circulating refrigeration unit 16 to cool the substrate placed on the copper vessel 33 and to cool the droplets suspended by the stainless steel needle 23 inside the circulating refrigeration head 24.

[0083] During the cooling process, according to the droplet impact velocity required by the experimental target, the relevant parameters of the linear motor control module 21 are adjusted to change the height between the stainless steel needle 23 and the substrate on the copper vessel 33, so as to obtain the predetermined experimental impact velocity. Once the temperature of the substrate and the droplet have reached the target temperature required by the experiment, the valve of the liquid nitrogen tank 15 is closed.

[0084] Turn on the high-speed camera 44, computer 45 and LED fiber optic light 52 to record the process of droplet impact and solidification.

[0085] At the same time, the micro-injection pump 26 is turned on, and the micro-injection pump 26 slowly pushes the syringe 25 so that the droplet suspended below the stainless steel needle 23 is detached from the stainless steel needle and impacts the low-temperature substrate target on the copper vessel 33 at a preset impact speed.

[0086] Once the data is saved, turn off the LED fiber optic light 52, turn on the vacuum pump 34, and control the robotic arm 32 via the Arduino control module 31 to remove the impact residue substrate. Then, place a new substrate target to prepare for the next impact experiment.

[0087] Based on the main idea, this invention changes the original experimental operations and parameter preparation that required opening the box and performing them inside the box to the operation of the internal equipment controlled by external devices without opening the box. This greatly improves experimental efficiency and accuracy and saves experimental costs.

[0088] In summary, this invention provides a modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device. Through an external controller, operations inside the sealed chamber can be performed without opening the chamber. This not only improves experimental efficiency and reduces time and economic costs, but also allows for the acquisition of more experimental data samples with minimal time investment, meeting the need for obtaining substrates with greater supercooling. Furthermore, the experimental device significantly reduces nitrogen consumption and eliminates the need for frequent opening and closing of the sealed chamber, thereby lowering costs and making experimental conditions more precise.

[0089] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A modular, low-temperature, low-humidity, visually sealed droplet impact experimental device, characterized in that, The system includes an environmental cooling and dehumidification device for dehumidifying the sealed box (13) and cooling the substrate placed inside the sealed box (13); the environmental cooling and dehumidification device is equipped with a substrate treatment system for treating the droplet residue after each impact of the substrate. The substrate treatment system includes a copper vessel (33) placed inside the sealed box (13), the substrate is placed inside the copper vessel (33), and a robotic arm (32) is provided on one side of the copper vessel (33). The robotic arm (32) is connected to an Arduino control module (31) set outside the sealed box (13). The substrate treatment system is equipped with a vacuum pump (34); a droplet control and generation device is provided above the substrate treatment system. The droplet control and generation device is used to stably generate droplets and control the impact speed and temperature of the droplets. The droplet control and generation device is fixed on the linear motor guide rail (22). The linear motor guide rail (22) is electrically connected to the linear motor control module (21) outside the sealed box (13); a data acquisition system and an auxiliary system are provided on one side of the substrate treatment system. The data acquisition system is used to monitor and acquire the experimental data obtained by the substrate treatment system. The auxiliary system is used to provide a light source for the data acquisition system.

2. The modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device according to claim 1, characterized in that, The environmental cooling and dehumidification device includes an atmospheric pressure nitrogen tank (11), which is connected to a sealed box (13) and a substrate treatment system placed inside the sealed box (13). The substrate treatment system is connected to a liquid nitrogen tank (15) via a flow control valve (14).

3. The modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device according to claim 2, characterized in that, A pressure reducing valve (12) and a pressure gauge are installed on the connecting pipeline between the atmospheric pressure nitrogen tank (11) and the sealed box (13). A box pressure monitoring pressure gauge assembly (17) for monitoring and regulating the internal pressure of the sealed box (13) is installed on the top of the sealed box (13).

4. The modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device according to claim 1, characterized in that, The droplet control and generation device includes a stainless steel needle (23) installed inside the sealed housing (13). The stainless steel needle (23) is connected to a syringe (25) installed outside the sealed housing (13) via a pipeline. One end of the syringe (25) is connected to a micro-injection pump (26). The stainless steel needle (23) is surrounded by a circulating cooling head (24). The circulating cooling head (24) is connected to a circulating refrigerator (16) installed outside the sealed housing (13) via a circulation pipeline.

5. The modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device according to claim 1, characterized in that, The bronze vessel (33) consists of a lower layer (335), a middle layer (333) and an upper layer (331) from bottom to top. A porous medium plate (332) is provided in the middle layer (333).

6. The modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device according to claim 1, characterized in that, The robotic arm (32) includes a base (324), on which a wrist (323) is provided. The wrist (323) is connected to the forearm (321) via the upper arm (322). Servo motors are respectively provided between the wrist (323) and the base (324), between the wrist (323) and the upper arm (322), and between the upper arm (322) and the forearm (321). The forearm (321) includes a hand structure made of a porous screen and a vacuum suction cup. The hand structure is used to process particulate substrates, and the vacuum suction cup is connected to a vacuum pump (34) via a hose.

7. The modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device according to claim 1, characterized in that, The data acquisition system includes a first point temperature thermocouple (41) and a humidity detector (43) installed at the base processing system, a second point temperature thermocouple (42) installed at the droplet control and generation device, and a high-speed camera (44) installed on one side of the sealed box (13). The first point temperature thermocouple (41), the second point temperature thermocouple (42) and the humidity detector (43) are connected to the computer (45) via a temperature and humidity acquisition device (46) installed outside the sealed box (13). The computer (45) is connected to the high-speed camera (44).

8. The modular, low-temperature, low-humidity, visible, sealed droplet impact experimental device according to claim 1, characterized in that, The auxiliary system includes a controller (51), which is connected to an LED fiber optic lamp (52) on one side of the substrate processing system inside the sealed enclosure (13).

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