Measurement Method and Measurement Equipment for Bubble Behavior and Micro Liquid Film at the Bubble Bottom

Abstract

The present invention provides a method for measuring bubble behavior and the micro-liquid film at the bubble bottom, which relates to the technical field of thermal-hydraulic tests and is designed to solve the problem that the complex bubble interface behavior caused by boiling phase change cannot be fully studied. The method for measuring bubble behavior and the micro-liquid film at the bubble bottom includes observing and recording the micro-liquid film from the bottom direction of the bubble; monitoring the liquid temperature in the gas-liquid-solid three-phase contact limit region; obtaining the temperature distribution of the heating surface at the bubble bottom; and monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bubble bottom. The method for measuring bubble behavior and the micro-liquid film at the bubble bottom provided by the present invention can provide effective assistance for studying the complex bubble interface behavior caused by boiling phase change.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal-hydraulic tests, and more particularly, to a method and an apparatus for measuring bubble behavior and the micro liquid film at the bubble bottom. Background Art

[0002] Due to its considerable heat transfer capacity, the boiling heat transfer process accompanied by the dynamic evolution of bubble behavior has gradually become a widely adopted thermal design solution and is applied in high-power heat flux distribution systems in fields such as nuclear reactor engineering, thermal energy engineering, electronic cooling, and aerospace. The heat transfer in the above two-phase system mainly occurs through the evaporation of the liquid layer at the bubble bottom and the evaporation at the vapor-liquid interface. However, the complex bubble interface behavior and the heat transfer of the micro liquid film at the bubble bottom caused by boiling phase change pose great difficulties to the design of the above heat flux system.

[0003] In the early stage, most of the studies on two-phase boiling were based on the image analysis of bubble behavior using high-speed photography technology, and the micro-liquid film at the bottom of the bubble could not be obtained. With the rapid development of high-temperature infrared thermometry technology, people can obtain wall temperature transient data above kilohertz. At the same time, the high heat flux ITO (indium–tin-oxide) transparent heating film technology enables the high-speed infrared thermometry and high-speed photography technology to match each other. Subsequently, Gerardi et al. from MIT (Massachusetts Institute of Technology) in the United States studied the wall temperature change and the evolution of dry spots and micro-liquid layers at the bottom of the bubble during the bubble nucleation process on the heating surface of atmospheric pressure pool nucleate boiling based on high-speed infrared and high-speed photography technology (see (C. Gerardi, J. Buongiorno, L.-w. Hu, T. McKrell, Study of bubble growth in water pool boiling through synchronized, infrared thermometry and high-speed video, International Journal of Heat and Mass Transfer, 53(19)(2010)4185-4192)). Recently, Giustini et al. combined high-speed cameras with total emission technology to obtain the evolution law of the size of the dry spots at the bottom of the bubbles in atmospheric pressure pool nucleate boiling, and analyzed the heat transfer mechanism during the bubble growth and departure stage in combination with high-speed infrared data (see G. Giustini, I. Kim, H. Kim, Comparison between modelled and measured heat transfer rates during the departure of a steam bubble from a solid surface, International Journal of Heat and Mass Transfer, 148(2020)119092).Estrada-Pérez et al. from TAMU in the United States used high-speed cameras and high-speed infrared to synchronously measure the morphology and wall temperature changes during bubble nucleation, slip, and detachment processes (see C.E. Estrada-Pérez, Y.A. Hassan, B. Alkhudhiri, J. Yoo, Time-resolved measurements of liquid–vapor thermal interactions throughout the full life-cycle of sliding bubbles at subcooled flow boiling conditions, International Journal of Multiphase Flow, 99 (2018).

[0004] Amidu et al. from Kyung Hee University in South Korea heated the surface with an ITO film about 5 microns thick and used a combination of high-speed infrared cameras, high-speed cameras, and total reflection technology to measure the wall temperature changes, heat flux components, and the evolution of bubble and dry patch sizes during bubble nucleation, growth, and slip in flow boiling. (See M.A. Amidu, S. Jung, H. Kim, Direct experimental measurement for partitioning of wall heat flux during subcooled flow boiling: Effect of bubble areas of influence factor, International Journal of Heat and Mass Transfer, 127 (2018) 515-533.) Summary of the Invention

[0005] The first object of the present invention is to provide a method for measuring bubble behavior and the micro-liquid film at the bottom of the bubble to solve the technical problem that the complex bubble interface behavior caused by boiling phase change cannot be fully studied at present.

[0006] The method for measuring bubble behavior and the micro-liquid film at the bottom of the bubble provided by the present invention includes: observing and recording the micro-liquid film from the bottom direction of the bubble; monitoring the liquid temperature in the gas-liquid-solid three-phase contact limit region; obtaining the temperature distribution of the heating surface at the bottom of the bubble; monitoring the bubble dynamic behavior and the spatio-temporal distribution characteristics of the dry area at the bottom of the bubble.

[0007] The beneficial effects brought by the measurement method of the bubble behavior and the micro-liquid film at the bubble bottom in the present invention are as follows:

[0008] By observing the micro-liquid film from the bottom direction of the bubble, the thickness change law of the micro-liquid film can be obtained. Monitoring the liquid temperature in the gas-liquid-solid three-phase contact limit region and the temperature distribution of the heating surface at the bubble bottom is conducive to obtaining the temperature distribution during bubble generation. Monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bubble bottom can obtain the results of the change of bubble-related parameters over time. In summary, this measurement method can obtain many parameters in the bubble generation process more comprehensively, providing effective help for studying the complex bubble interface behavior caused by boiling phase change.

[0009] In the preferred technical solution, a high-speed camera is arranged below the bubble to observe and record the bright and dark alternating circular fringes caused by the optical path difference of the reflected light on the upper and lower surfaces of the micro-liquid film, and calculate the thickness of the micro-liquid film.

[0010] In the preferred technical solution, when calculating the thickness of the micro-liquid film, Δ = 2nδ. For the dark ring, Δ = (m + 0.5)·λ, δ = (m + 0.5)·λ / 2n. For the bright ring, Δ = mλ, δ = mλ / 2n; where Δ is the optical path difference, δ is the thickness of the micro-liquid film, λ is the laser wavelength, n is the refractive index of deionized water, and m is an integer greater than or equal to 0.

[0011] In the preferred technical solution, in the monitoring of the liquid temperature in the gas-liquid-solid three-phase contact limit region, sodium fluorescein is used as the fluorescent agent sensitive to liquid temperature, a thermocouple is used to measure the temperature, and a high-speed camera is used to monitor the liquid temperature in the gas-liquid-solid three-phase contact line region.

[0012] In the preferred technical solution, a high-speed infrared thermal imager is used to monitor and record the temperature distribution of the heating body, and the hydrophilic / hydrophobic coating temperature is obtained by measuring the fluid temperature, the temperature of the quartz glass, and the liquid temperature in the gas-liquid-solid three-phase contact line region.

[0013] In the preferred technical solution, T layer =[(E total -E glass -E water -E bubble ) / (3τ layer ε layer σ)] 0.25 , T layer is the hydrophilic / hydrophobic coating temperature, E total is the total thermal radiation, E glass is the thermal radiation of the quartz glass, E water is the local liquid thermal radiation of the three-phase contact line, E bubble is the thermal radiation of the bubble, τ layeris the transmittance of the hydrophilic / hydrophobic coating, ε layer is the emissivity of the hydrophilic / hydrophobic coating, σ is the Stefan–Boltzmann constant; and E total 、E glass 、E water and E bubble are obtained from E = τεσT 4 where τ = e-kσ; where k, τ, ε, and T are the object absorption coefficient, transmittance, emissivity, and temperature of their respective media, and σ is the Stefan–Boltzmann constant.

[0014] In a preferred technical solution, the monitoring of the bubble dynamics behavior and the spatio-temporal distribution characteristics of the bubble bottom dry area include:

[0015] Using a high-speed camera equipped with a macro lens to monitor the bubble dynamics behavior and the spatio-temporal distribution characteristics of the bubble bottom dry area from the bottom of the bubble, and obtaining characteristic parameters.

[0016] In a preferred technical solution, the monitoring of the bubble dynamics behavior and the spatio-temporal distribution characteristics of the bubble bottom dry area include:

[0017] Sequentially convert the visualized pictures obtained by the high-speed camera into double-precision pictures, grayscale pictures, and binary pictures, and perform filtering, corrosion, dilation, and filling on the binary pictures, and identify, extract, and calculate the white connected areas in the pictures, and use statistical functions such as Gaussian distribution, Inverse Gaussian distribution, Gama distribution, and Weibull distribution to conduct analysis to obtain the spatio-temporal distribution characteristics of the typical characteristic parameters of the bubble bottom dry area and the bubble dynamics.

[0018] The second object of the present invention is to provide a measuring device to solve the technical problem that the complex bubble interface behavior caused by boiling phase change cannot be fully studied.

[0019] The measuring device provided by the present invention is applied to the above-mentioned measurement method of the bubble behavior and the micro liquid film at the bubble bottom. The measuring device includes ITO conductive glass, a laser emitter, and an infrared camera. The ITO conductive glass is provided with a hydrophilic / hydrophobic coating. The laser emitter is directed at the ITO conductive glass through a first beam splitter, and the infrared camera is oriented towards the ITO conductive glass.

[0020] The beneficial effects brought by the measuring device of the present invention are:

[0021] A light source can be provided for the bubble generation region through a laser emitter. The ITO conductive glass transmits the laser, and an infrared camera can be used to observe the bubble generation region, record the temperature distribution of the heating wall surface, obtain the temperature distribution of the heating surface at the bottom of the bubble, so as to observe the bubble growth process.

[0022] In a preferred technical solution, it further includes a second beam splitter, a first high-speed camera and a second high-speed camera. The first beam splitter is optically connected to the first high-speed camera through the second beam splitter, and is optically connected to the second high-speed camera through the second beam splitter and a mirror. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the background art, the following will briefly introduce the drawings required for use in the description of the embodiments or the background art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0024] Figure 1 It is a schematic diagram of the measurement method for bubble behavior and the micro liquid film at the bottom of the bubble provided in Embodiment 1 of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the measurement device used in the measurement method for bubble behavior and the micro liquid film at the bottom of the bubble provided in Embodiment 1 of the present invention;

[0026] Figure 3(a) is a medium distribution diagram of the bubble generation region in the measurement method for bubble behavior and the micro liquid film at the bottom of the bubble provided in Embodiment 1 of the present invention; Figure 3(b) is a partial enlarged view of Figure 3(a) to show the generation principle of interference fringes; Figure 3(c) is a schematic diagram of the interference fringes;

[0027] Figure 4(a) is a schematic diagram of the visualization picture obtained by the high-speed camera; Figure 4(b) is a schematic diagram of the process of converting the visualization picture; Figure 4(c) is a black and white schematic diagram of the obtained bubble distribution; Figure 4(d) is a statistical distribution characteristic diagram of the equivalent diameter of the dry area at the bottom of the bubble; Figure 4(e) is a flowchart of the detailed steps for monitoring the dynamic behavior of the bubble and the spatio-temporal distribution characteristics of the dry area at the bottom of the bubble.

[0028] Explanation of the Reference Numerals:

[0029] 11 - ITO conductive glass; 12 - laser emitter; 13 - infrared camera; 14 - first beam splitter; 15 - second beam splitter; 16 - first high-speed camera; 17 - second high-speed camera; 18 - mirror. Detailed Embodiments

[0030] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0031] Embodiment 1:

[0032] Figure 1 It is a schematic diagram of the measurement method for bubble behavior and the micro-liquid film at the bubble bottom provided in Embodiment 1 of the present invention; Figure 2 It is a schematic structural diagram of the measurement device used in the measurement method for bubble behavior and the micro-liquid film at the bubble bottom provided in Embodiment 1 of the present invention. As Figures 1 - 2 shown, the measurement method for bubble behavior and the micro-liquid film at the bubble bottom provided in Embodiment 1 of the present invention includes: observing and recording the micro-liquid film from the bubble bottom orientation; monitoring the liquid temperature in the gas-liquid-solid three-phase contact limit region; obtaining the temperature distribution of the heating surface at the bubble bottom; monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out region at the bubble bottom.

[0033] By observing the micro-liquid film from the bubble bottom orientation, the thickness change law of the micro-liquid film can be obtained. Monitoring the liquid temperature in the gas-liquid-solid three-phase contact limit region and the temperature distribution of the heating surface at the bubble bottom is conducive to obtaining the temperature distribution when the bubble is generated. Monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out region at the bubble bottom can obtain the results of the change of bubble-related parameters over time. In summary, this measurement method can more comprehensively obtain many parameters in the bubble generation process and provide effective help for studying the complex bubble interface behavior caused by boiling phase change.

[0034] Among them, in this application, ITO conductive glass is used to realize the transparent heating surface for the optical subsystem to photograph. The light transmittance of the ITO conductive glass is ≥85%, the sheet resistance is ≤5Ω, and the size is 1mm×10mm×100mm. The ITO conductive glass can be prepared by depositing an ITO (Indium-Tin Oxide) conductive film on the tempered quartz glass, and sequentially sputtering Al 2 O 3 protective layer and hydrophilic / hydrophobic coating on the ITO conductive film. Finally, the light transmittance of the formed heating body is not less than 80%.

[0035] As Figures 3(a) - 3(c) shown, preferably, the high-speed camera disposed below the bubble is used to observe and record the bright and dark alternating circular fringes caused by the optical path difference of the reflected light on the upper and lower surfaces of the micro-liquid film, and calculate the thickness of the micro-liquid film.

[0036] Among them, Fig. 3(a) is the medium distribution diagram of the bubble generation region; Fig. 3(b) is a partial enlarged view of Fig. 3(a) to show the generation principle of interference fringes. In the figure, the leftmost part of the upper surface of the micro liquid film is the relatively original gas-liquid interface, and the relatively right part is the new gas-liquid interface. The hollow arrow below the upper surface of the micro liquid film in the figure is the schematic diagram of the reflected light of the gas-liquid interface, the solid dark arrow below the micro liquid film is the schematic diagram of the incident laser beam, and the solid light arrow below the micro liquid film is the schematic diagram of the reflected light of the bottom cross-section of the micro liquid film. Fig. 3(c) is the schematic diagram of interference fringes. The arrow in the horizontal direction in the figure indicates that the interference fringes move to the right.

[0037] Specifically, a high-speed camera equipped with a macro lens can be used for observation. The shooting rate of the high-speed camera can be 10,000 fps. Observe and record the bright and dark circular fringes caused by the optical path difference of the reflected light on the upper and lower surfaces of the micro liquid film from the bottom direction of the bubble, that is, Newton's rings. Since the laser enters the micro liquid film from the ITO glass and then enters the bubble from the micro liquid film, both belong to the situation of light entering from an optically denser medium to an optically thinner medium. Therefore, there is no half-wave loss at the ITO glass-micro liquid film interface and the micro liquid film-bubble cross-section. So the optical path difference can cause the two reflected light beams to interfere with each other to form bright and dark interference fringes.

[0038] By observing the bright and dark circular fringes and calculating the thickness of the micro liquid film, the distribution of the thickness of the micro liquid film in the radial direction of the bubble radius can be obtained, which is conducive to studying the evolution of the bubble in space.

[0039] As shown in Fig. 3, preferably, when calculating the thickness of the micro liquid film, Δ = 2nδ. For the dark ring, Δ = (m + 0.5)·λ, δ = (m + 0.5)·λ / 2n. For the bright ring, Δ = mλ, δ = mλ / 2n; where, Δ is the optical path difference, δ is the thickness of the micro liquid film, λ is the laser wavelength, n is the refractive index of deionized water, and m is an integer greater than or equal to 0.

[0040] Among them, for the refractive index of deionized water, in this embodiment, it is taken as 1.32.

[0041] As Figure 1 shown, preferably, when monitoring the liquid temperature in the gas-liquid-solid three-phase contact limit region, sodium fluorescein is used as a fluorescent agent sensitive to liquid temperature, a thermocouple is used to measure the temperature, and a high-speed camera is used to monitor the liquid temperature in the gas-liquid-solid three-phase contact line region.

[0042] Specifically, a thermocouple can be used to calibrate the liquid temperature so that the temperature accuracy displayed by the fluorescence method is controlled within the range of ±0.5 °C, thereby improving the temperature observation accuracy.

[0043] By using sodium fluorescein as a liquid temperature-sensitive fluorescent agent, temperature monitoring can be achieved by measuring optical signals. Moreover, continuous temperature monitoring can be realized by observing image signals, and the temperature situation that is almost continuously distributed spatially at the same moment over a large range can also be obtained.

[0044] As Figure 1 shown, preferably, a high-speed infrared thermal imager is used to monitor and record the temperature distribution of the heating body, and the hydrophilic / hydrophobic coating temperature is obtained by measuring the fluid temperature, the quartz glass temperature, and the liquid temperature in the gas-liquid-solid three-phase contact line region.

[0045] Specifically, the high-speed infrared thermal imager cannot directly monitor the temperature distribution of the heating body itself. Since the thermal radiation obtained by the high-speed infrared thermal imager is not generated by only one thing, the heating body, but is the superposition of the thermal radiations of multiple things, therefore, by obtaining the measured fluid temperature, the quartz glass temperature, and the liquid temperature in the gas-liquid-solid three-phase contact line region, the influence of the thermal radiation of other things can be eliminated, and the temperature of the heating body can be obtained separately.

[0046] As Figure 1 shown, preferably, T layer = [(E total - E glass - E water - E bubble ) / (3τ layer ε layer σ)] 0.25 , T layer is the hydrophilic / hydrophobic coating temperature, E total is the total thermal radiation, E glass is the quartz glass thermal radiation, E water is the local liquid thermal radiation of the three-phase contact line, E bubble is the bubble thermal radiation, τ layer is the transmittance of the hydrophilic / hydrophobic coating, ε layer is the emissivity of the hydrophilic / hydrophobic coating, σ is the Stefan-Boltzmann constant; and E total , E glass , E water and E bubble are obtained from E = τεσT 4 , τ = e -kσ ; where k, τ, ε, T are the object absorption coefficient, transmittance, emissivity, and temperature of their respective media, and σ is the Stefan-Boltzmann constant.

[0047] Specifically, the total thermal radiation E total obtained by the infrared thermal imager is mainly composed of the environmental thermal radiation E environment , the quartz glass thermal radiation E glass, Thermal radiation E of ITO film ITO , Thermal radiation E of Al2O3 coating Al2O3 , Hydrophilic / hydrophobic coating E layer Thermal radiation, local liquid thermal radiation of three-phase contact line water , Bubble thermal radiation E bubble , And thermal radiation E of the flow channel body channel It consists of, that is total E = environment E + glass E + ITO +

[0048] E Al2O3 E + layer E + water E + bubble E + channel .

[0049] Among them, due to the environmental thermal radiation E environment and the thermal radiation E of the flow channel body channel are significantly smaller than the other thermal radiations, so they can be ignored. Therefore, the above formula can be changed to: E total E = glass E + ITO E + Al2O3 E + layer E + water E + bubble . And E total , E glass , E water and E bubble are obtained from E = τεσT 4 . Specifically:

[0050] E glass = τ glass ε glass σ glass T glass 4 , τ glass , ε glass , T glass are the transmittance, emissivity and temperature of quartz glass respectively, and σ glass is the Stefan-Boltzmann constant; and τ glass = e -kglassσglass , where k glass is the object absorption coefficient of quartz glass, and e is the base of the natural logarithm. T glass can be obtained by setting a patch-type thermocouple on the quartz glass.

[0051] E water = τ water ε water σ water Twater 4 , τ water , ε water , T water are the transmittance, emissivity, and temperature of the local liquid of the three-phase contact line, respectively. σ water is the Stefan-Boltzmann constant.

[0052] τ water = e -k waterσwater , k water is the object absorption coefficient of the local liquid of the three-phase contact line. The fluid temperature T water can also be obtained by a patch-type thermocouple.

[0053] E bubble = τ bubble ε bubble σ bubble T bubble 4 , τ bubble , ε bubble , T bubble are the transmittance, emissivity, and temperature of the gas

[0054] bubble, respectively. σ bubble is the Stefan-Boltzmann constant. τ bubble = e -kbubbleσbubble , k bubble is the object absorption coefficient of the bubble. And T bubble can be approximately equal to the saturation temperature.

[0055] That is, E total - E glass - E water + E bubble = E ITO + E Al2O3 + E layer .

[0056] ITO film, Al 2 O 3 coating, and hydrophilic / hydrophobic coating can be approximately considered to have the same temperature. Then (E total - E glass - E water + E bubble ) / 3 = E layer .

[0057] And according to E = τεσT 4 , we can get T layer = [(E total - E glass - E water - E bubble ) / (3τ layer εlayer σ)] 0.25 Thus, the temperature of the heating surface at the bottom of the bubble, i.e., the temperature of the hydrophilic / hydrophobic coating, can be obtained.

[0058] As Figures 4(a) - 4(e) shown, preferably, monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bottom of the bubble includes: using a high-speed camera equipped with a macro lens to monitor the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bottom of the bubble from the bottom of the bubble, and obtaining characteristic parameters.

[0059] Through the high-speed camera, an image of the dry-out area at the bottom of the bubble can be obtained, and then the image is transformed to obtain the characteristic parameters of the dry-out area at the bottom of the bubble.

[0060] Preferably, monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bottom of the bubble includes:

[0061] The visual pictures obtained by the high-speed camera, i.e., the visual pictures obtained by the high-speed camera in Fig. 4(a) (since color pictures are not allowed in patent application documents, so this figure appears in the form of a grayscale picture. In the figure, the position of the edge of the bubble is the vapor-liquid-solid contact line, and the right edge in the figure is the edge of the flow channel), are sequentially transformed into double-precision pictures, grayscale pictures and binary pictures, and the binary pictures are subjected to filtering, corrosion, dilation, filling processing, and the white connected areas in the pictures are identified, extracted and calculated. As shown in Fig. 4(c) finally obtained through the process shown in Fig. 4(b), Fig. 4(b) is a schematic diagram of the process of transforming the visual picture; Fig. 4(c) is a black-and-white schematic diagram of the obtained bubble distribution; Gaussian distribution, inverse Gaussian distribution, gamma distribution, and Weibull distribution statistical functions are used for analysis to obtain the spatio-temporal distribution characteristics of the typical characteristic parameters of the dry-out area at the bottom of the bubble and the bubble dynamics. As shown in Fig. 4(d) which is a statistical distribution characteristic diagram of the equivalent diameter of the dry-out area at the bottom of the bubble, since the gray scale picture makes the distinction of each curve in the figure not obvious, it is specifically explained that in the order of the peak values of each curve in the figure decreasing step by step, each curve is the curve successively shown in the upper right of Fig. 4(d). In Fig. 4(d), PDF represents Probability Distribution Functions, the probability distribution function. Specifically, the detailed steps of monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bottom of the bubble can be shown in Fig. 4(e).

[0062] Specifically, the bubble density and the equivalent diameter of the bubble adhering wall area can be statistically calculated according to the actual width of the flow channel.

[0063] Example 2:

[0064] As Figure 2As shown, the measuring device provided in the second embodiment is applied to the above-mentioned method for measuring bubble behavior and the micro-liquid film at the bottom of the bubble. The measuring device includes an ITO conductive glass 11, a laser emitter 12, and an infrared camera 13. A hydrophilic / hydrophobic coating is provided on the ITO conductive glass. The laser emitter is directed at the ITO conductive glass through a first beam splitter 14, and the infrared camera 13 faces the ITO conductive glass.

[0065] Specifically, the ITO conductive glass 11 is arranged in a boiling flow channel. The boiling flow channel is made of PC transparent material, and deionized water is introduced into the boiling flow channel.

[0066] The laser emitter 12 can provide a light source for the bubble generation region. The ITO conductive glass 11 transmits the laser, and the infrared camera 13 can observe the bubble generation region, record the temperature distribution of the heating wall surface, obtain the temperature distribution of the heating surface at the bottom of the bubble, so as to observe the bubble growth process.

[0067] Preferably, it further includes a second beam splitter 15, a first high-speed camera 16, and a second high-speed camera 17. The first beam splitter 14 is optically connected to the first high-speed camera 16 through the second beam splitter 15, and is optically connected to the second high-speed camera 17 through the second beam splitter 15 and a mirror 18. Among them, the first high-speed camera 16, the second high-speed camera 17, and the infrared camera 13 are all electrically connected to a synchronizer to obtain synchronous measurement results of each measuring device.

[0068] Through the first high-speed camera 16, laser interference imaging can be observed. The thickness of the micro-liquid film can be deduced from the bright and dark circular fringes obtained by the laser interference imaging. Through the second high-speed camera 17, the local liquid temperature of the three-phase contact line can be obtained by using the laser-induced fluorescence imaging method.

[0069] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

[0070] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0071] In the above embodiments, the descriptions of directions such as “upper” and “lower” are all based on the drawings.

[0072] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0073] Thus, the present invention will not be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A measurement method for bubble behavior and the micro-liquid film at the bubble bottom, characterized in that, it includes: Observing and recording the micro-liquid film from the bubble bottom orientation; Monitoring the liquid temperature in the gas-liquid-solid three-phase contact limit region: Using sodium fluorescein as a fluorescent agent sensitive to liquid temperature, measuring the temperature with a thermocouple, and monitoring the liquid temperature in the gas-liquid-solid three-phase contact line region with a high-speed camera; Using a high-speed infrared thermal imager to monitor and record the temperature distribution of the heating body, and obtaining the hydrophilic / hydrophobic coating temperature by measuring the fluid temperature, the temperature of the quartz glass, and the liquid temperature in the gas-liquid-solid three-phase contact line region; T layer =[(E total -E glass -E water -E bubble ) / (3τ layer ε layer σ)] 0.25 , T layer is the hydrophilic / hydrophobic coating temperature, E total is the total thermal radiation, E glass is the thermal radiation of the quartz glass, E water is the local liquid thermal radiation of the three-phase contact line, E bubble is the thermal radiation of the bubble, τ layer is the transmittance of the hydrophilic / hydrophobic coating, ε layer is the emissivity of the hydrophilic / hydrophobic coating, σ is the Stefan-Boltzmann constant; and E total , E glass , E water and E bubble are obtained from E = τεσT 4 , τ = e- kσ ; where k, τ, ε, and T are the object absorption coefficient, transmittance, emissivity, and temperature of their respective media; Obtaining the temperature distribution of the heating surface at the bubble bottom; Monitoring the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bubble bottom: Using a high-speed camera equipped with a macro lens to monitor the bubble dynamics behavior and the spatio-temporal distribution characteristics of the dry-out area at the bubble bottom from the bubble bottom, and obtaining characteristic parameters: Sequentially converting the visualized pictures obtained by the high-speed camera into double-precision pictures, grayscale pictures and binary pictures, and performing filtering, corrosion, dilation, filling processing on the binary pictures, and identifying, extracting, calculating the white connected areas in the pictures, and using Gaussian distribution, inverse Gaussian distribution, gamma distribution, and Weibull distribution statistical functions to conduct analysis to obtain the spatio-temporal distribution characteristics of the typical characteristic parameters of the dry-out area at the bubble bottom and the bubble dynamics.

2. The measurement method for bubble behavior and the micro-liquid film at the bubble bottom according to claim 1, characterized in that, Observing and recording the bright and dark alternating circular fringes caused by the optical path difference of the reflected light on the upper and lower surfaces of the micro-liquid film through a high-speed camera arranged below the bubble, and calculating the thickness of the micro-liquid film.

3. The measurement method for bubble behavior and the micro-liquid film at the bubble bottom according to claim 2, characterized in that, When calculating the thickness of the micro-liquid film, Δ = 2nδ. For the dark ring, Δ = (m + 0.5)·λ, δ = (m + 0.5)·λ / 2n. For the bright ring, Δ = mλ, δ = mλ / 2n; where Δ is the optical path difference, δ is the thickness of the micro-liquid film, λ is the laser wavelength, n is the refractive index of deionized water, and m is an integer greater than or equal to 0.

4. A measurement device applied to the measurement method for bubble behavior and the micro-liquid film at the bubble bottom according to any one of claims 1-3, characterized in that, The measurement device includes ITO conductive glass, a laser emitter and an infrared camera. The ITO conductive glass is provided with a hydrophilic / hydrophobic coating. The laser emitter is directed at the ITO conductive glass through a first beam splitter. The infrared camera faces the ITO conductive glass; The measurement device further includes a second beam splitter, a first high-speed camera and a second high-speed camera. The first beam splitter is optically connected to the first high-speed camera through the second beam splitter, and is optically connected to the second high-speed camera through the second beam splitter and a reflector.

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