Vibration low-temperature surface condensation frosting and freezing thawing experiment system

Abstract

The invention relates to a vibration low-temperature surface cold condensation defrosting and freezing thawing experiment system, and belongs to the technical field of ice and defrosting prevention. Modular design is adopted, the experimental system is divided into a plurality of modules according to functions, each module is composed of a plurality of elements with different functions, and by changing the elements and experimental conditions of the experimental system, related experiments such as condensation, frosting, freezing and thawing of the vibration low-temperature surface can be carried out in the same experimental system; spatial layout is optimized, key system elements such as a refrigeration element and a vibration unit are installed in a centralized mode, other experiment system elements are installed in a scattered mode, and therefore temperature control and vibration control over an experiment flat plate are achieved at the same time, interference among experiment modules is reduced, and stability of the experiment system is improved.

Description

Technical Field

[0001] The present invention relates to an experimental system for vibration low-temperature surface condensation frosting and freezing melting, belonging to the technical field of ice and frost prevention and removal. Background Art

[0002] As a common phenomenon in nature, icing and frosting have caused many adverse effects in human life and production fields such as refrigeration and cryogenics, aerospace, marine transportation, electrical engineering, and telecommunication. In severe cases, it may lead to casualties and economic losses. In the field of refrigeration and cryogenics, after frosting on the surface of a refrigerator, cold storage, or air conditioner evaporator, the thermal conductivity of the frost layer decreases and an insulating layer is formed, hindering the transfer of cold energy, resulting in a decrease in evaporation temperature and an increase in compressor power consumption; in the aerospace field, icing on the wing, tail, or engine air intake will damage the streamlined design, leading to a decrease in lift coefficient and an increase in drag, which may cause stall or out-of-control; in the marine transportation field, icing on the deck and superstructure will increase the center of gravity height and reduce the ship's stability, and icing on the port crane track will trigger loading and unloading accidents, resulting in a decrease in logistics efficiency; in the telecommunication field, icing on the microwave antenna reflector surface causes signal scattering (such as the 5G high-frequency band is more sensitive), and icing on the satellite-borne antenna will lead to a reduction in communication bandwidth, all of which will reduce the quality of signal transmission. Therefore, understanding and mastering the icing / frosting and ice / frost prevention and removal mechanisms have positive significance for the development of economic, national defense, people's livelihood, science and technology and other fields, and it is necessary to carry out scientific experimental research related to icing and frosting.

[0003] In engineering applications, the initial stages of the macroscopic icing and condensation frosting processes on the surface of equipment are often related to the problem of single microscopic droplet icing, and in order to ensure safe operation and maintenance, these equipment often use heating methods to remove ice / frost. Easily icing / frosting equipment (such as heat exchanger fins, photovoltaic / thermal panels) often generates different forms of mechanical vibration on the icing / frosting surface during operation. For example, the wind-induced vibration frequency of a communication base station antenna is 1-10 Hz, the vibration frequency of a refrigeration compressor is 20-200 Hz, the vibration frequency of an electric vehicle heat pump during road driving is 0.4-25 Hz, and the vibration frequency of an aircraft wing can reach 100 Hz. Existing research has shown that external vibration not only changes the dynamic behavior of droplets but also has a significant impact on heat and mass transfer processes such as boiling, condensation, evaporation, and solidification. Therefore, it is necessary to deeply explore the icing / frosting process on the vibration low-temperature surface.

[0004] In the existing icing and frosting experimental systems, for the patent "An experimental system for icing effect of fairing under simulated real vibration conditions" with the patent application number 202410322121.1, the fairing is placed in the ice wind tunnel experimental system, and a vibration table is installed at the bottom to study the anti-icing and de-icing performance of the fairing. This experimental system occupies a large space and has a narrow application range. It is applied to engineering tests and cannot be used for experimental research on the icing and frosting mechanism. For the patent "A small refrigeration platform frosting experimental device" with the patent application number 202123104185.5, a refrigerator and a humidity generator are used, and it is connected to a stationary test end via a rectifying section and a blower. The data obtained by this method does not include images of the frosting process and is only applicable to the study of frosting phenomena in a stationary state and cannot be extended to experimental conditions under vibration. For the patent "An experimental system for frosting on a cold surface" with the patent application number 201921646405.7, the frosting surface is placed on a water-cooled head connected to a low-temperature constant-temperature water bath, and a combination of a microscope and a camera directly above is used to photograph the frosting process. This device only uses the water-cooled head connected to the low-temperature constant-temperature water bath for refrigeration, and the cooling process takes a long time and the temperature of the cold surface cannot be accurately controlled. For the patent "A visualization experimental device for frosting of trace water" with the patent application number 202011561566.3, airflows with different trace water vapor contents are introduced onto a constant-temperature low-temperature cold surface to form a frost layer, and the law of sublimation frosting of trace water vapor in the mixed atmosphere under different operating conditions is explored by measuring the mass of the frost layer. This device requires forced air convection and cannot be used for experimental research on frosting under natural convection. The patent "An experimental device for frosting and its application" with the patent application number 202210331485.7 also has the same limitation.

[0005] The existing low-temperature surface icing and frosting experimental systems have the following deficiencies: (1) The existing experimental devices cannot simultaneously achieve precise control of vibration conditions and surface temperature; (2) The existing experimental devices have fewer functions and rarely involve research on related processes such as condensation and freezing droplet melting on vibrating low-temperature surfaces; (3) The types of data obtained are few, the means of obtaining experimental images are relatively single, and most are from single-perspective shooting.

[0006] Currently, the relevant experimental devices and methods for icing and frosting on vibrating low-temperature surfaces are still not clear, the mechanism during the icing and frosting process on vibrating surfaces is still not well understood, and the information that can be obtained by existing experimental devices is relatively limited. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: Overcoming the deficiencies of the prior art, a condensation, frosting, freezing, and melting experimental system for vibrating low-temperature surfaces is proposed, aiming to conduct experimental research on low-temperature condensation, frosting, freezing, and melting on vibrating surfaces to explore the mechanism during the icing and frosting process on vibrating surfaces.

[0008] The technical solution of the present invention is as follows:

[0009] A vibration low-temperature surface condensation frosting and freezing-thawing experiment system, which is composed of a vibration module 1, a heat dissipation module 2, an environmental control module 3, and a data acquisition module 4;

[0010] The vibration module 1 is used to provide vibration conditions for the experimental section 5. The vibration module 1 mainly consists of a signal generator 101, a signal amplifier 102, a vibration unit 103, and a support plate 104;

[0011] The signal generator 101 is used to generate vibration excitation signals with different parameters, including signal frequency f0, period T0, amplitude A0, maximum acceleration a0, phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ0, etc., and is connected to the signal amplifier 102 through a wire;

[0012] The signal amplifier 102 is used to receive the excitation signal generated by the signal generator 101 and amplify its power, and then transmit it to the vibration unit 103 and the oscilloscope 406 in the data acquisition module 4 through two different output interfaces respectively;

[0013] The vibration unit 103 is used to output vibrations with different parameters in response to the vibration excitation signal, including vibration frequency f s , period T s , amplitude A s , acceleration a s , phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ s , etc., and transmit the vibration to the refrigeration module 2 through the support plate 104;

[0014] The parameters between the vibration conditions of the vibration unit 103 and the vibration excitation signal of the signal generator 101 satisfy frequency f s = f0, period T s = T0, amplitude A s = M A A0, maximum acceleration a s = M a a0, phase waveform is the same, duty cycle δ s = δ0. Among them, M A and M a are amplification parameters, which are determined by adjusting the signal amplifier 102 according to requirements. In addition, the waveform is a sine wave or a cosine wave, and the following relationship also holds between the amplitude and the maximum acceleration:

[0015] a0 = (2πf0) 2 A0, a S= (2πf0) 2 A S

[0016] The heat dissipation module 2 is used to take away the excess heat generated by the refrigeration unit 301 in the environmental control module 3. The heat dissipation module 2 mainly includes a heat exchanger 201, a working fluid pipeline 202, and a low-temperature constant temperature cold source 203;

[0017] The heat exchanger 201 adopts a microchannel heat exchanger and is connected to the low-temperature constant temperature cold source 203 through the working fluid pipeline 202;

[0018] The environmental control module 3 is used to provide the required temperature and humidity for the experimental section 5, and is mainly composed of a refrigeration unit 301, a refrigeration unit control device 302, a humidifier 303, and an air conditioner 304;

[0019] The refrigeration unit 301 has two working modes: heating and refrigeration. The refrigeration unit 301 is located above the heat exchanger 201 and is in close contact with it. A heat-conducting medium is coated on the contact surface between the refrigeration unit 301 and the heat exchanger 201 to enhance the heat exchange effect. The refrigeration unit 301 can adopt a thermoelectric cooler;

[0020] The refrigeration unit control device 302 is connected to the refrigeration unit 301 through a wire and is used to change the working mode of the refrigeration unit 301, thereby controlling the temperature of the experimental section 5 to meet the requirements of low-temperature and high-temperature experiments;

[0021] Both the humidifier 303 and the air conditioner 304 are used to adjust the environmental humidity and temperature;

[0022] The data acquisition module 4 is used to acquire signal data such as the temperature, humidity, and vibration of the experimental section 5. The data acquisition module 4 mainly consists of a cold light source 401, a top-view camera 402, a side-view camera 403, an acceleration sensor 404, a signal conditioner 405, an oscilloscope 406, a temperature sensor 407, a temperature and humidity sensor 408, and a data acquisition instrument 409;

[0023] The cold light source 401 can adjust the irradiation angle to provide bright light for the shooting of experimental images;

[0024] The top-view camera 402 and the side-view camera 403 are respectively located above and on the side of the experimental section 5 and are used to obtain experimental images from different perspectives. Industrial cameras, high-speed cameras, infrared cameras, etc. can be used;

[0025] The acceleration sensor 404 is installed at the bottom of the vibration unit 103. The acceleration sensor 404 vibrates together with the output end of the vibration unit 103 to obtain vibration conditions;

[0026] The acceleration sensor 404 is connected to the oscilloscope 406 and the data acquisition instrument 409 through the signal conditioner 405, and can simultaneously display the vibration condition parameters on the oscilloscope 406 and collect them into the data acquisition instrument 409. The vibration condition parameters include the vibration frequency f s , the period T s , the amplitude A s , the acceleration a s , the phase waveforms (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), the duty cycle δ s and other parameters;

[0027] The temperature sensor 407 is located between the experimental section 5 and the refrigeration unit 301. The temperature sensor 407 is a thermocouple or a resistance thermometer, and can also be combined by a single or multiple sensors. By measuring the average value of the multi-point temperature, it characterizes the temperature of the experimental section 5 and reduces the measurement deviation;

[0028] The temperature and humidity sensor 408 is mainly used to measure the temperature and relative humidity of the environment. Both the temperature sensor 407 and the temperature and humidity sensor 408 are connected to the data acquisition instrument 409 for collecting the surface temperature of the experimental section 5 and the environmental temperature and humidity data;

[0029] The experimental section 5 includes an experimental flat plate 501 and an experimental environmental chamber 502;

[0030] The experimental flat plate 501 can select suitable materials according to specific requirements such as experimental objectives and contents, including metal materials such as copper, aluminum, and stainless steel, non-metal materials such as glass, silicon wafers, and polytetrafluoroethylene. Necessary processing can be carried out on the experimental flat plate 501 to adjust the surface parameters to meet specific performances, including surface size, surface contact angle θ, roughness Ra, micro-nano structure, chemical composition, etc. The installation parameters of the experimental flat plate 501 can be adjusted, including installation horizontal angle, vertical angle, etc.;

[0031] The experimental environmental chamber 502 is used to protect the experimental flat plate 501, is in communication with the environment, and can use transparent materials to facilitate the acquisition of experimental images.

[0032] The experimental flat plate 501 is fixedly connected to the refrigeration unit 301, the heat exchanger 201, and the support plate 104 through clamps and studs, and can move together with the output end of the vibration unit 103 during the experiment.

[0033] Beneficial effects

[0034] The present invention adopts a modular design. According to functions, the experimental system is divided into several modules, and each module consists of multiple components with different functions. By changing the components of the experimental system and experimental conditions, relevant experiments such as condensation, frosting, freezing, and melting on a vibrating low-temperature surface can be carried out in the same experimental system; the spatial layout is optimized, with key system components such as refrigeration components and vibration units installed centrally, while other experimental system components are installed dispersedly. In this way, both temperature control and vibration control of the experimental plate are achieved simultaneously, and interference between various experimental modules is reduced, improving the stability of the experimental system; multi-task integration is realized. By using system components such as thermocouples, temperature and humidity sensors, acceleration sensors, and image acquisition devices installed in the experimental system, experimental contents such as the temperature of the experimental plate, ambient temperature and humidity, vibration information, and images of the experimental process can be obtained simultaneously; the vibration conditions are feedback-regulated. By using the closed-loop feedback regulation of signal generators, power amplifiers, vibration units, acceleration sensors, signal demodulators, and oscilloscopes, precise control of the vibration conditions is achieved; experimental exploration of condensation, frosting, freezing, and melting on a vibrating low-temperature surface is realized, and vibration conditions can be applied to the cold plate. The experimental system has a high degree of integration and occupies a small space, facilitating research work in the laboratory. It is possible to simultaneously collect images of the experimental process of condensation, frosting, freezing, and melting on a vibrating low-temperature surface from both top-down and side views, making the experimental research more efficient. Each subsystem in the experimental system is designed to be replaceable and mutually compatible, and different modules can be replaced according to the needs of experimental research, having a certain degree of expandability. The present invention has a low cost, is convenient, safe, and practical. Description of the Drawings

[0035] Figure 1 Overall schematic diagram of the experimental system;

[0036] Figure 2 Detailed schematic diagram of the experimental system;

[0037] Figure 3 Schematic diagram of the arrangement of temperature sensors;

[0038] Figure 4 Flow chart of the condensation experiment on a vibrating surface;

[0039] Figure 5 Flow chart of the frosting experiment on a vibrating surface;

[0040] Figure 6 Flow chart of the water droplet freezing experiment on a vibrating surface;

[0041] Figure 7 Flow chart of the melting experiment of frozen water droplets on a vibrating surface;

[0042] Figure 8 Excitation signal voltage and amplitude intensity at different times;

[0043] Figure 9 Relationship between the sine-wave excitation voltage signal and the amplitude of the vibration condition

[0044] Figure 10 Stationary (A s = 0 μm) and vibrating (A s = 1000 μm) experimental images of the edge region during the condensation process on the surface

[0045] Figure 11 Stationary (A s = 0 μm) and vibrating (A s = 1000 μm) equivalent width of the edge region during the condensation process on the surface

[0046] Figure 12 Stationary (A s = 0 μm) and vibrating (A s = 1000 μm) experimental images of different moments during the frosting process on the surface

[0047] Figure 13 Stationary (A s = 0 μm) and vibrating (A s = 1000 μm) equivalent frost layer thickness during the frosting process on the surface

[0048] Figure 14 Stationary (A s = 0 μm) and vibrating (A s = 100 μm) experimental images of the water droplet freezing process on the surface

[0049] Figure 15 Stationary (A s = 0 μm) and vibrating (A s = 100 μm) contour of the frozen water droplet at t = 8 s on the surface

[0050] Figure 16 Stationary (A s = 0 μm) and vibrating (A s = 200 μm) experimental images of the frozen water droplet melting process on the surface

[0051] Figure 17 Stationary (A s = 0 μm) and vibrating (A s = 200 μm) contour of the melting water droplet at t = 12 s on the surface Detailed implementation manner

[0052] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0053] As Figure 1As shown, the present invention is a low-temperature surface condensation frosting and freezing-thawing experiment system, which is integrally composed of a vibration module 1, a heat dissipation module 2, an environmental control module 3, a data acquisition module 4, and an experimental section 5.

[0054] As Figure 2 shown, the vibration module 1 is used to provide vibration conditions for the experimental section 5, and is mainly composed of a signal generator 101, a signal amplifier 102, a vibration unit 103, and a support plate 104;

[0055] The signal generator 101 generates vibration excitation signals with different parameters, including signal frequency f0, period T0, amplitude A0, maximum acceleration a0, phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ0, etc., and is connected to the signal amplifier 102 through a wire;

[0056] The signal amplifier 102 receives the excitation signal generated by the signal generator 101 and amplifies its power, and then transmits it to the vibration unit 103 and the oscilloscope 406 respectively through two different output interfaces;

[0057] The vibration unit 103 can respond to the vibration excitation signal and output vibrations with different parameters, including vibration frequency f s , period T s , amplitude A s , acceleration a s , phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ s etc., and transmits the vibration to the upper cooling module 2 through the support plate 104;

[0058] Generally speaking, the parameters between the vibration conditions of the vibration unit 103 and the vibration excitation signal of the signal generator 101 satisfy frequency f s = f0, period T s = T0, amplitude A s = M A A0, maximum acceleration a s = M a a0, phase waveform is the same, duty cycle δ s = δ0. Among them, M A and M a are amplification parameters, which are determined by adjusting the signal amplifier 102 according to requirements. In addition, when the waveform is a sine wave or a cosine wave, the following relationship also holds between the amplitude and the maximum acceleration:

[0059] a0 = (2πf0) 2 A0, a S = (2πf0) 2 AS (1)

[0060] The heat dissipation module 2 is used to remove the excess heat generated by the refrigeration unit 301, and mainly includes a heat exchanger 201, a working medium pipeline 202, and a low-temperature constant temperature cold source 203;

[0061] The heat exchanger 201 can adopt a microchannel heat exchanger and is connected to the low-temperature constant temperature cold source 203 through the working medium pipeline 202;

[0062] The environmental control module 3 is used for the temperature and humidity required by the experimental section 5, and mainly consists of a refrigeration unit 301, a refrigeration unit control device 302, a humidifier 303, and an air conditioner 304;

[0063] The refrigeration unit 301 has two working modes of heating and refrigeration. The refrigeration unit 301 is located above the heat exchanger 201 and is in close contact with it. The contact surface between the refrigeration unit 301 and the heat exchanger 201 is coated with a heat-conducting medium to enhance the heat exchange effect. The refrigeration unit 301 can adopt a semiconductor refrigeration chip; the refrigeration unit control device 302 is connected to the refrigeration unit 301 through a wire and is used to change the working mode of the refrigeration unit 301, thereby controlling the temperature of the experimental section 5 to meet the requirements of low-temperature and high-temperature experiments; the humidifier 303 and the air conditioner 304 are both used to adjust the environmental humidity and temperature.

[0064] The data acquisition module 4 is used to acquire signal data such as the temperature, humidity, and vibration of the experimental section 5, and mainly consists of a cold light source 401, a top-view camera 402, a side-view camera 403, an acceleration sensor 404, a signal conditioner 405, an oscilloscope 406, a temperature sensor 407, a temperature and humidity sensor 408, and a data acquisition instrument 409. The cold light source 401 can adjust the irradiation angle to provide bright light for the shooting of experimental images;

[0065] The top-view camera 402 and the side-view camera 403 are respectively located above and on the side of the experimental section 5 and are used to obtain experimental images from different perspectives. Industrial cameras, high-speed cameras, infrared cameras, etc. can be used; the acceleration sensor 404 is installed at the bottom of the vibration unit 103, and the acceleration sensor 404 vibrates together with the output end of the vibration unit 103 to obtain vibration conditions;

[0066] The acceleration sensor 404 is connected to the oscilloscope 406 and the data acquisition instrument 409 through the signal conditioner 405, and the vibration condition parameters can be simultaneously displayed on the oscilloscope 406 and collected into the data acquisition instrument 409. The vibration condition parameters include vibration frequency f s , period T s , amplitude A s , acceleration a s , phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δs parameters such as;

[0067] The temperature sensor 407 is located between the experimental section 5 and the refrigeration unit 301. As Figure 3 shown, the temperature sensor 407 is a thermocouple or a resistance thermometer, and can also be a combination of single or multiple sensors. By measuring the average value of the multi-point temperature, the temperature of the experimental section 5 is characterized, and the measurement deviation is reduced. The temperature and humidity sensor 408 is mainly used to measure the temperature and relative humidity of the environment. Both the temperature sensor 407 and the temperature and humidity sensor 408 are connected to the data acquisition instrument 409 to collect the surface temperature and environmental temperature and humidity data of the experimental section 5.

[0068] The experimental section 5 includes an experimental plate 501 and an experimental environmental chamber 502. The experimental plate 501 can select suitable materials according to specific requirements such as experimental objectives and contents, including metal materials such as copper, aluminum, and stainless steel, and non-metal materials such as glass, silicon wafers, and polytetrafluoroethylene. Necessary processing can be carried out on the experimental plate 501 to adjust the surface parameters to meet specific performances, including surface size, surface contact angle θ, roughness Ra, micro-nano structure, chemical composition, etc. The installation parameters of the experimental plate 501 can be adjusted, including installation horizontal angle, vertical angle, etc.; the experimental environmental chamber 502 is used to protect the experimental plate 501, is connected to the environment, and can use transparent materials to facilitate the acquisition of experimental images.

[0069] The experimental plate 501 is fixedly connected to the refrigeration unit 301, the heat exchanger 201, and the support plate 104 through clamps and studs, and can move together with the output end of the vibration unit 103 during the experiment.

[0070] Adopt Figure 2 The experimental system shown to carry out the vibration surface condensation experiment. As Figure 4 shown, the following is the specific operation process:

[0071] Adjust the experimental section 5: Select an experimental plate 501 with a suitable material according to specific requirements such as experimental objectives and contents, process the experimental plate 501, and adjust the installation parameters of the experimental plate 501;

[0072] Turn on the data acquisition module 4: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the data acquisition instrument 409, and record the experimental plate temperature T s , ambient temperature T e , ambient humidity RH and other parameters; Turn on the cold light source 401, the top-down camera 402, and the horizontal camera 403, adjust the acquisition parameters such as the acquisition frequency and acquisition duration, and record the transient images of the experimental plate 501 during the experiment;

[0073] Turn on the vibration module 1: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the signal conditioner 404 and the oscilloscope 405, and set the surface vibration frequency fs 、Period T s 、Amplitude A s 、Acceleration a s 、Phase Waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ s and other parameters are adjusted to the target parameters;

[0074] Turn on the environmental control module 3 and the heat dissipation module 2: Start the low-temperature constant temperature cold source 203 to make the refrigerant circulate in the working medium pipeline 202 and activate the heat exchanger 201. Lower the temperature of the refrigeration unit 301 through the temperature controller 302, and read the surface temperature collected by the temperature sensor 407 on the data acquisition instrument 409, and set the experimental flat plate temperature T s Reduce it to the target temperature T c (meeting T c < 0 °C) and maintain it constant;

[0075] Adjust the environmental control module 3: Change the operating parameters of the humidifier 303 and the air conditioner 304 to adjust the environmental temperature T e and the environmental humidity RH in the experimental environmental chamber 502 to the target environmental temperature T e0 and the target environmental humidity RH0 respectively.

[0076] Data processing and analysis: Process the data such as temperature and images obtained from the experiment, and analyze the condensation characteristics on the vibrating surface, including the volume V, morphology and distribution of the condensate droplets, the condensation dynamic process, the surface coverage rate C, the droplet contact angle θ, the condensation rate v c and the temperature distribution of the experimental flat plate, etc.

[0077] Adopt Figure 2 the experimental system shown to carry out the frosting experiment on the vibrating surface. As Figure 5 shown below is the specific operation process:

[0078] Adjust the experimental section 5: According to the specific requirements such as the experimental objectives and content, select an experimental flat plate 501 made of a suitable material, process the experimental flat plate 501, and adjust the installation parameters of the experimental flat plate 501;

[0079] Turn on the data acquisition module 4: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the data acquisition instrument 409, and record the experimental flat plate temperature T s 、environmental temperature T e 、environmental humidity RH and other parameters; Turn on the cold light source 401, the top-down camera 402 and the horizontal camera 403, adjust the acquisition parameters such as the acquisition frequency and acquisition duration, and record the transient images of the experimental flat plate 501 during the experiment;

[0080] Turn on the vibration module 1: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the signal conditioner 404 and the oscilloscope 405, and set the surface vibration frequency f s , period T s , amplitude A s , acceleration a s , phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ s to the target parameters;

[0081] Turn on the environmental control module 3 and the heat dissipation module 2: Start the low-temperature constant temperature cold source 203 to make the refrigerant circulate in the working medium pipeline 202 and activate the heat exchanger 201. Lower the temperature of the refrigeration unit 301 through the temperature controller 302, and read the surface temperature collected by the temperature sensor 407 on the data acquisition instrument 409. Lower the experimental flat plate temperature T s to the target temperature T c (satisfying T c < 0 °C) and maintain it constant;

[0082] Adjust the environmental control module 3: Change the operating parameters of the humidifier 303 and the air conditioner 304 to adjust the environmental temperature T e and environmental humidity RH in the experimental environmental chamber 502 to the target environmental temperature T e0 and the target environmental humidity RH0 respectively.

[0083] Data processing and analysis: Process the data such as temperature and images obtained from the experiment, and analyze the frosting characteristics on the vibrating surface, including the duration of each frosting stage, frosting rate v f , frost layer thickness h f , surface roughness Ra of the frost layer, contour evolution of the frost layer profile, surface temperature distribution of the frost layer, etc.

[0084] Use the Figure 2 shown experimental system to conduct the water droplet freezing experiment on the vibrating surface. As Figure 6 shown, the following is the specific operation process:

[0085] Adjust the experimental section 5: According to the specific requirements such as the experimental objectives and content, select an experimental flat plate 501 of appropriate material, process the experimental flat plate 501, and adjust the installation parameters of the experimental flat plate 501;

[0086] Turn on the data acquisition module 4: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the data acquisition instrument 409, and record the experimental flat plate temperature T s , environmental temperature T e, parameters such as environmental humidity RH, etc.; Turn on the cold light source 401, the downward camera 402 and the horizontal camera 403, adjust the acquisition parameters such as the acquisition frequency and acquisition duration, and record the transient images of water droplets during the experiment;

[0087] Turn on the environmental control module 3 and the heat dissipation module 2: Start the low-temperature constant temperature cold source 203 to make the refrigerant circulate in the working medium pipeline 202 and activate the heat exchanger 201. Lower the temperature of the refrigeration unit 301 through the temperature controller 302, and read the surface temperature collected by the temperature sensor 407 on the data acquisition instrument 409, and set the temperature of the experimental flat plate to T s Reduce it to the target temperature T c (satisfy T c <0 °C) and maintain it constant; Place the water droplet on the experimental flat plate 501. According to the specific requirements such as the experimental objectives and content, the water droplet parameters can be adjusted, including the water droplet volume V0, salinity S, gas content , etc.;

[0088] Turn on the vibration module 1: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the signal conditioner 404 and the oscilloscope 405, and set the surface vibration frequency f s , period T s , amplitude A s , acceleration a s , phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ s , etc. to the target parameters;

[0089] Data processing and analysis: Process the data such as temperature and images obtained from the experiment, and analyze the freezing characteristics of water droplets on the vibrating surface, including the water droplet morphology, the shape and position of the ice-water phase interface, the nucleation time t n , the duration of the freezing process t s , freezing rate v s , the internal temperature distribution of the droplet, etc.

[0090] Use the Figure 2 shown experimental system to conduct the melting experiment of frozen water droplets on the vibrating surface. As Figure 7 shown, the following is the specific operation process:

[0091] Adjust the experimental section 5: According to the specific requirements such as the experimental objectives and content, select an experimental flat plate 501 made of a suitable material, process the experimental flat plate 501, and adjust the installation parameters of the experimental flat plate 501;

[0092] Turn on the data acquisition module 4: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the data acquisition instrument 409, and record the temperature T of the experimental flat plate s , environmental temperature T e, parameters such as environmental humidity RH, etc.; Turn on the cold light source 401, the downward shooting camera 402 and the horizontal shooting camera 403, adjust the acquisition parameters such as the acquisition frequency and acquisition duration, and record the transient images of water droplets during the experiment process;

[0093] Turn on the environmental control module 3 and the heat dissipation module 2: Start the low-temperature constant-temperature cold source 203 to make the refrigerant circulate in the working medium pipeline 202 and activate the heat exchanger 201. Lower the temperature of the refrigeration unit 301 through the temperature controller 302, and read the surface temperature collected by the temperature sensor 407 on the data acquisition instrument 409, and set the temperature of the experimental flat plate T s Reduce it to the target temperature T c (Meet T c < 0 °C) and maintain it constant; Place the water droplet on the experimental flat plate 501, and according to the specific requirements such as the experimental objectives and content, the water droplet parameters can be adjusted, including the water droplet volume V0, salinity S, gas content etc., and wait for the water droplet to freeze completely;

[0094] Turn on the vibration module 1: Adjust the acquisition parameters such as the acquisition frequency and acquisition duration of the signal conditioner 404 and the oscilloscope 405, and set the surface vibration frequency f s , period T s , amplitude A s , acceleration a s , phase waveform (such as sine wave, cosine wave, square wave, sawtooth wave, etc.), duty cycle δ s etc. to the target parameters;

[0095] Adjust the environmental control module 3: Switch the working mode of the refrigeration unit 301 to the heating mode through the temperature controller 302, and raise the temperature of the experimental flat plate 501 to the target temperature T h (Meet T h < 0 °C), and wait for the water droplet to melt completely.

[0096] Data processing and analysis: Process the data such as temperature and images obtained from the experiment, and analyze the melting characteristics of the frozen water droplets on the vibrating surface, including the water droplet morphology, the shape and position of the ice-water phase interface, the melting start time t s , melting end time t e , melting process duration t m , melting rate v m , internal temperature distribution, etc.

[0097] Example 1

[0098] The vibration unit 103 uses an electromagnetic exciter, which consists of an electromagnet iron core with a coil and an armature. By inputting a periodically changing current into the electromagnet coil, a periodically changing excitation force is generated between the output shaft and the electromagnet. The magnitude of the excitation voltage determines the magnitude of the current in the electromagnet coil, which in turn affects the magnetic field strength generated by the electromagnet. The greater the magnetic field strength, the greater the excitation force between the output shaft and the electromagnet, thus increasing the vibration amplitude of the output shaft; conversely, when the excitation voltage decreases, the vibration amplitude also decreases. At the same time, a change in the frequency of the excitation voltage will directly cause a change in the frequency of the excitation force, thereby also changing the vibration frequency of the output shaft.

[0099] As Figure 8 shown, a regular sine wave is generated by the signal generator 101 and the signal amplifier 102. The frequency f0 of the sine wave is 50 Hz, the period T0 is 0.02 s, and the amplitude A0 is 5.44 V. The corresponding vibration conditions generated by the vibration unit 103 have a frequency f s = 50 Hz, a period T s = 0.02 s, and an amplitude A s = 749.9 μm. Further, as Figure 9 shown, through multiple experimental side views and data fitting, the relationship between the sine wave excitation voltage signal and the vibration condition amplitude can be obtained as:

[0100] A S = 139A0

[0101] where A0 is the amplitude of the sine wave excitation voltage signal (unit: V), and A s is the amplitude of the vibration condition (unit: μm).

[0102] Example 2

[0103] A vibration condensation experiment on a bare copper surface is carried out under the conditions of an environmental temperature of T e = 23.5 °C and a humidity of RH = 60%. During the condensation process, the temperature of the experimental flat plate is set to T s = T c = -10 °C. The surface vibration waveform is a regular sine wave, with a vibration frequency f s = 50 Hz, a period T s = 0.02 s, and an amplitude A s = 1000 μm. Figure 10 Shown are experimental images at different times during the condensation process on the stationary (A s = 0 μm) and vibrating (A s = 1000 μm) surfaces recorded by an industrial camera from a top-down perspective. The edge regions have been marked. Figure 11 Shown are the stationary (A s = 0 μm) and vibrating (A sThe variation curve of the equivalent width of the edge region of the condensation process over time on the surface (with a certain size, e.g., 1000μm) indicates that this experimental device can be used to analyze the condensation characteristics on a vibrating surface.

[0104] Example 3

[0105] Frost formation experiments were conducted on a vibrating bare copper surface under the conditions that the ambient temperature and humidity were T e = 23.5°C and RH = 60% respectively. During the frost formation process, the temperature of the experimental plate was set to T s = T c = -10°C. The surface vibration waveform was a regular sine wave, with a vibration frequency f s = 50Hz, a period T s = 0.02s, and an amplitude A s = 1000μm. Figure 12 The following are the experimental images at different times during the frost formation process on the stationary (A s = 0μm) and vibrating (A s = 1000μm) surfaces recorded by an industrial camera from a side view perspective. Figure 13 The following shows the variation curve of the equivalent frost layer thickness over time during the frost formation process on the stationary (A s = 0μm) and vibrating (A s = 1000μm) surfaces, indicating that this experimental device can be used to analyze the frost formation characteristics on a vibrating surface.

[0106] Example 4

[0107] Droplet freezing experiments were conducted on a vibrating bare aluminum surface under the conditions that the ambient temperature and humidity were T e = 25°C and RH = 30% respectively. The droplets were deionized water with a volume of V0 = 20μL. During the freezing process, the surface temperature was set to T s = T c = -15°C. The surface vibration waveform was a regular sine wave, with a vibration frequency f s = 50Hz, a period T s = 0.02s, and an amplitude A s = 100μm. Figure 14 The following are the experimental images at different times during the droplet freezing process on the stationary (A s = 0μm) and vibrating (A s = 100μm) surfaces recorded by a high-speed camera. Figure 15 The following shows the frozen droplet contours at t = 8s on the stationary (A s = 0μm) and vibrating (A s = 100μm) surfaces further extracted, indicating that this experimental device can be used to analyze the freezing characteristics of droplets on a vibrating surface.

[0108] Example 5

[0109] The vibration bare aluminum surface frozen water droplet melting experiment was carried out under the conditions that the ambient temperature and humidity were T e = 25 °C and RH = 30%, respectively. The water droplets were deionized water with a volume of V0 = 20 μL. The surface temperature during the freezing process was set to T s = T c = -15 °C. The surface vibration waveform was a regular sine wave, and the vibration frequency f s = 50 Hz, the period T s = 0.02 s, and the amplitude A s = 200 μm. The surface temperature during the melting process was set to T s = T h = 15 °C. Figure 16 The experimental images at different moments during the melting process of the frozen water droplets on the static (A s = 0 μm) and vibrating (A s = 200 μm) surfaces recorded by a high-speed camera are shown. Figure 17 The profiles of the melting water droplets at t = 12 s on the static (A s = 0 μm) and vibrating (A s = 200 μm) surfaces further extracted are shown, indicating that this experimental device can be used to analyze the melting characteristics of frozen water droplets on a vibrating surface.

[0110] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A vibration low-temperature surface condensation frosting and freezing-thawing experiment system, characterized in that: The experiment system consists of a vibration module, a heat dissipation module, an environmental control module, a data acquisition module, and an experimental section; The vibration module is used to provide vibration conditions for the experimental section; The heat dissipation module is used to take away the excess heat generated by the environmental control module; The environmental control module is used to provide the required temperature and humidity for the experimental section; The data acquisition module is used to collect the temperature data, humidity data, and vibration data of the experimental section.

2. The vibration low-temperature surface condensation frosting and freezing-thawing experiment system according to claim 1, characterized in that: The vibration module mainly consists of a signal generator, a signal amplifier, a vibration unit, and a support plate; The heat dissipation module mainly includes a heat exchanger, a working medium pipeline, and a low-temperature constant-temperature cold source; The environmental control module mainly consists of a refrigeration unit, a refrigeration unit control device, a humidifier, and an air conditioner; The data acquisition module mainly consists of a cold light source, a top-down camera, a side camera, an acceleration sensor, a signal conditioner, an oscilloscope, a temperature sensor, a temperature and humidity sensor, and a data acquisition instrument.

3. The vibration low-temperature surface condensation frosting and freezing-thawing experiment system according to claim 2, characterized in that: The signal generator is used to generate vibration excitation signals with different parameters, and the signal generator is connected to the signal amplifier through a wire; The parameters of the vibration excitation signal include signal frequency f0, period T0, amplitude A0, maximum acceleration a0, phase φ0, waveform, and duty cycle δ0; The signal amplifier is used to receive the excitation signal generated by the signal generator, amplify its power, and then transmit it to the vibration unit and the oscilloscope in the data acquisition module through two different output interfaces respectively; The vibration unit is used to respond to the vibration excitation signal and output vibrations with different parameters, and transmit the vibration to the refrigeration module through the support plate; The parameters between the vibration conditions of the vibration unit and the vibration excitation signal of the signal generator satisfy the frequency f s = f0, the period T s = T0, the amplitude A s = M A A0, the maximum acceleration a s = M a a0, the phase φ s = φ0, the waveforms are the same, the duty cycle δ s = δ0, where M A and M a are amplification parameters, determined by adjusting the signal amplifier according to requirements, the waveform is a sine wave or a cosine wave, and the following relationship also holds between the amplitude and the maximum acceleration: a0 = (2πf0) 2 A0, a S = (2πf0) 2 A S 。 4. The vibration low-temperature surface condensation frosting and freezing-thawing experiment system according to claim 2, characterized in that: The heat exchanger adopts a microchannel heat exchanger and is connected to the low-temperature constant-temperature cold source through a working medium pipeline.

5. The vibration low-temperature surface condensation frosting and freezing-thawing experiment system according to claim 2, characterized in that: The refrigeration unit has two working modes: heating and refrigeration. The refrigeration unit is located above the heat exchanger and is in close contact with it. The contact surface between the refrigeration unit and the heat exchanger is coated with a heat conduction medium to enhance the heat exchange effect. The refrigeration unit adopts a semiconductor refrigeration chip; The refrigeration unit control device is connected to the refrigeration unit through a wire and is used to change the working mode of the refrigeration unit, thereby controlling the temperature of the experimental section to meet the requirements of low-temperature and high-temperature experiments; Both the humidifier and the air conditioner are used to adjust the environmental humidity and temperature.

6. The vibration low-temperature surface condensation frosting and freezing-thawing experiment system according to claim 2, characterized in that: The cold light source is used to adjust the irradiation angle and provide bright light for the shooting of experimental images; The top-down camera and the side camera are respectively located above and on the side of the experimental section and are used to obtain experimental images from different perspectives; The acceleration sensor is installed at the bottom of the vibration unit, and the acceleration sensor vibrates together with the output end of the vibration unit to obtain vibration conditions; The acceleration sensor is connected to the oscilloscope and the data acquisition instrument through a signal conditioner, and can simultaneously display the vibration condition parameters on the oscilloscope and collect them into the data acquisition instrument; The temperature sensor is located between the experimental section and the refrigeration unit; The temperature and humidity sensor is mainly used to measure the ambient temperature and relative humidity. Both the temperature sensor and the temperature and humidity sensor are connected to the data acquisition instrument for collecting the surface temperature of the experimental section and the ambient temperature and humidity data.

7. The experimental system for vibration low-temperature surface condensation frosting and freezing-thawing according to claim 2, characterized in that: The experimental section includes an experimental flat plate and an experimental environment chamber, and the experimental environment chamber is used to protect the experimental flat plate.

8. The experimental system for vibration low-temperature surface condensation frosting and freezing-thawing according to claim 7, characterized in that: The experimental flat plate is fixedly connected to the refrigeration unit, the heat exchanger, and the support plate through clamps and studs, and moves together with the output end of the vibration unit during the experiment.

9. The experimental system for vibration low-temperature surface condensation frosting and freezing-thawing according to claim 2, characterized in that: The overhead camera and the side camera are industrial cameras, high-speed cameras or infrared cameras; The temperature sensor is a thermocouple or a resistance thermometer.

10. The experimental system for vibration low-temperature surface condensation frosting and freezing-thawing according to claim 2, characterized in that: The vibration condition parameters include the vibration frequency f s , the period T s , the amplitude A s , the acceleration a s , the phase φ s , the waveform, and the duty cycle δ s , and the waveform is a sine wave, a cosine wave, a square wave, or a sawtooth wave.

Images