Vacuum glass heat transfer coefficient measuring method and measuring device

Abstract

The invention discloses a vacuum glass heat transfer coefficient measuring method and device, and the method comprises the steps: placing to-be-detected vacuum glass in a vacuum chamber provided with a vacuumizing system and an air pressure detection device, enabling the air pressure detection device to display the air pressure value of the chamber in real time, and forming a uniform polarized light field perpendicular to the placement direction of the glass in the chamber; and during vacuumizing, the light spot is detected on the side, opposite to the light source, of the glass through a polarization analyzing polaroid, the air pressure value P is recorded when the light spot disappears, and then the heat transfer coefficient is calculated according to the air pressure value P. Based on the photoelastic principle, the air pressure in the vacuum glass is determined by observing stress light spot changes, then the heat transfer coefficient is accurately calculated, the method is not affected by the environment temperature, measurement repeatability is good, measurement can be rapidly completed, the measurement efficiency and accuracy are greatly improved, and the method is suitable for popularization and application. And the urgent requirement of the vacuum glass production detection field on accurate measurement of the heat transfer coefficient is effectively met.

Description

Technical Field

[0001] The invention relates to the technical field of building material production detection, and in particular to a method and a device for measuring the heat transfer coefficient of vacuum glass. Background Art

[0002] As a new type of building energy-saving material, vacuum glass plays an important role in the field of modern architecture. It consists of two pieces of tempered glass separated by a support, sealed around the periphery, and a vacuum layer in the middle. With the vacuum layer, it effectively blocks heat conduction and convection, has excellent thermal insulation performance, and is increasingly widely used.

[0003] In the research and application process of vacuum glass, the measurement of heat transfer coefficient is a key link. Traditional measurement methods, such as direct thermal measurement, require setting constant temperature cold plates and hot plates on both sides of the vacuum glass, maintaining a constant temperature difference through technical means, thereby generating heat flow through the glass, and then using specially designed electronic circuits to record the heat flow power, and obtain the heat transfer coefficient through a series of calculations. However, this method faces many challenges. It is extremely time-consuming to establish a uniform and stable temperature field. For example, the instrument published in patent CN2553378Y takes 30 to 60 minutes to measure, and some large heat transfer coefficient measurement devices even take about 20 hours. Moreover, the measurement results are easily affected by the ambient temperature, and the consistency of the temperature and humidity of the measurement environment is quite high, otherwise it is difficult to obtain repeatable results. The rapid measurement device disclosed in patent CN103376274A can detect quickly, but it is only suitable for rough judgment of whether the product is qualified or not. The measurement accuracy is low and it is more significantly affected by the ambient temperature.

[0004] Despite the limitations of traditional methods, researchers in related fields are still exploring new measurement methods, including the online detection method of vacuum degree of vacuum glass based on the law of optical reflection disclosed in CN107328519A. Figure 2As shown in the schematic diagram, this method is based on an innovative idea, that is, trying to use the reflection characteristics of light on the surface of vacuum glass to detect the vacuum degree, and then establish a correlation with the heat transfer coefficient. However, in the actual application process, this method exposes a series of difficult-to-overcome problems. Due to the existence of supports, the surface of vacuum glass shows periodic undulations under the action of internal and external pressure difference, like waves. This special surface morphology makes the incident points of incident light 1 and incident light 2 different when the light is incident, and the angles with the upper glass surface are also different, so the direction of the reflected light is also very different. In the actual glass processing link, the bending of the glass is difficult to achieve precise control, and large-scale bow and wave bending often occur, which makes it extremely difficult to accurately judge the reflection of the light. Especially when the air pressure in the sealed cavity drops to the critical point equal to the air pressure in the vacuum glass, the bending of the glass surface will undergo complex changes, and the angle change of the reflected light becomes more elusive. At the same time, glass of different thicknesses has different stiffness characteristics. Under the same internal and external pressure difference conditions, the thinner the glass, the greater the degree of bending. This further exacerbates the complexity of judging the deviation of reflected light, making it almost impossible to accurately determine the critical point.

[0005] In view of the above-mentioned problems existing in the existing measurement methods, there is an urgent need for a method and corresponding instrument for measuring the heat transfer coefficient of vacuum glass that can be accurate, fast and not excessively affected by the ambient temperature. Summary of the invention

[0006] In order to overcome the problems of long measurement time, susceptibility to ambient temperature interference, low precision and the like in traditional measurement methods, and to solve the problem that the existing detection method based on the law of optical reflection is difficult to accurately judge the light reflection situation and critical point due to the surface characteristics of vacuum glass, the present invention provides a method and a device for measuring the heat transfer coefficient of vacuum glass. The vacuum glass to be detected is placed in a specific vacuum chamber, the air pressure in the chamber is changed by a vacuum pumping system, and the internal air pressure value of the vacuum glass is determined by observing the change of the stress spot with the help of the photoelastic principle. Then, the heat transfer coefficient is calculated according to a precise calculation formula, so as to realize efficient and accurate measurement of the heat transfer coefficient of vacuum glass, and is completely unaffected by the ambient temperature. This satisfies the urgent need for accurate measurement of the heat transfer coefficient in the field of vacuum glass production and detection, and improves the measurement efficiency and accuracy.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for measuring heat transfer coefficient of vacuum glass comprises the following steps:

[0009] Step 1: placing the vacuum glass to be tested in a vacuum chamber, wherein the vacuum chamber is provided with a vacuum pumping system and an air pressure detection device, and the air pressure detection device can display the air pressure value of the vacuum chamber in real time;

[0010] Step 2: forming a uniform polarized light field in the vacuum chamber, wherein the direction of the polarized light field is perpendicular to the placement direction of the vacuum glass to be tested, so that the vacuum glass to be tested forms a star-shaped light spot at the support column;

[0011] Step 3: evacuate the vacuum chamber through the vacuum pumping system, detect the star-shaped light spot through the polarizer on the side of the vacuum glass to be detected opposite to the light source, stop the vacuum pumping operation when the star-shaped light spot disappears, and record the air pressure value P displayed by the air pressure detection device at this time;

[0012] Step 4: Calculate the heat transfer coefficient of vacuum glass based on the obtained air pressure value P.

[0013] In this scheme, first, the vacuum glass to be tested is placed in a vacuum chamber equipped with a vacuum system and an air pressure detection device. The air pressure detection device displays the air pressure value in real time for easy monitoring. Then, a uniform polarized light field perpendicular to the direction of glass placement is formed in the chamber to form a star-shaped light spot at the support column, which provides a visual basis for judging the state of the vacuum glass by the change of the light spot. Then, during the vacuuming process, the star-shaped light spot is detected by using a polarizing polarizer. When the light spot disappears, the vacuuming is stopped and the air pressure value P is recorded. This step cleverly uses the principle of photoelasticity to determine the critical point of the air pressure balance inside and outside the vacuum glass through the phenomenon of the disappearance of the light spot, thereby obtaining the important parameter for calculation. The internal air pressure value of the vacuum glass. Finally, the heat transfer coefficient of the vacuum glass is calculated based on the air pressure value P. The whole process is closely linked. Through precise operation steps and parameter acquisition, it provides an effective way to accurately measure the heat transfer coefficient of the vacuum glass, overcomes many disadvantages of traditional measurement methods, improves the accuracy and efficiency of measurement, and also solves the problem that the existing detection method based on the law of optical reflection is difficult to determine the critical point.

[0014] As a further technical solution of the method for measuring the heat transfer coefficient of vacuum glass, the air pressure value P is the internal air pressure value of the vacuum glass to be tested.

[0015] As a further technical solution for measuring the heat transfer coefficient of vacuum glass, the heat transfer coefficient U value of vacuum glass can be calculated as follows:

[0016]

[0017] Among them, C 内 is the inner surface heat transfer coefficient (constant), C 外 is the external surface heat transfer coefficient (constant), C 真空The formula is used to calculate the thermal conductivity of vacuum glass. Through this formula, various parameters obtained during the measurement process can be integrated and calculated to obtain the accurate U value of the heat transfer coefficient of vacuum glass. This not only provides a quantitative basis for accurately evaluating the thermal insulation performance of vacuum glass, but also provides a theoretical calculation framework for the entire measurement method.

[0018] As a further technical solution for the method of measuring the heat transfer coefficient of vacuum glass, the thermal conductivity of the vacuum glass is calculated according to the following formula:

[0019]

[0020] C1 is the thermal conductivity of the outer glass plate (constant), C2 is the thermal conductivity of the inner glass plate (constant), C' 真空 is the thermal conductivity of the vacuum layer, which is calculated by the following formula: C' 真空 =C 辐射 +C 支 +C 气 .

[0021] As a further technical solution to the method for measuring the heat transfer coefficient of vacuum glass, the radiation thermal conductivity is calculated according to the following formula:

[0022]

[0023] σ is the Stefan-Boltzmann constant, σ = 5.67×10-8W / (m2·K4), T m为 The average absolute temperature of the gas spacer (K), ε1, ε2 are the average temperature of the two glass surfaces in the spacer at T m Corrected radiance under ;

[0024] The thermal conductivity of the support is calculated as follows:

[0025]

[0026] λg is the thermal conductivity of glass [W / (m·K)] (constant), h is the height of the support (m) (measurable), a is the radius of the contact area between the support column (16) and the glass (m) (measurable), b is the support array spacing (m) (measurable), λz is the thermal conductivity of the support column (16) [W / (m·K)] (constant);

[0027] The residual gas thermal conductivity is calculated as follows:

[0028] C 气 =0.6P.

[0029] A device for measuring heat transfer coefficient of vacuum glass adopts a method for measuring heat transfer coefficient of vacuum glass in the above technical solution, comprising:

[0030] A vacuum chamber, wherein a cavity for accommodating the vacuum glass to be tested is arranged inside the vacuum chamber, and the cavity is connected to the air pressure detection device and the vacuum pumping system;

[0031] A light source system, wherein the light source system forms a polarized light field on one side of the vacuum glass to be inspected, so that the vacuum glass to be inspected forms a star-shaped light spot at a supporting column;

[0032] A measuring system is provided on the other side of the vacuum glass to be detected, wherein the measuring system comprises an image acquisition device and an image analysis and processing system, wherein the image acquisition device monitors the image information of the star-shaped light spot in real time and transmits the image information to the image analysis and processing system, and when the image analysis and processing system determines that the star-shaped light spot completely disappears, the image analysis and processing system records the air pressure value displayed by the air pressure detection device at this moment.

[0033] In this scheme, the vacuum chamber provides a closed and adjustable air pressure space for the entire measurement. It is connected to the air pressure detection device and the vacuum system, so that the air pressure changes in the chamber can be monitored in real time, and the air pressure environment can be changed by vacuum operation, creating conditions for accurately measuring the air pressure inside the vacuum glass. The light source system forms a polarized light field on one side of the vacuum glass to be detected and causes a star-shaped light spot to form at the support column, which provides an intuitive and effective visual basis for judging the internal state of the vacuum glass through the change of the light spot. The image acquisition device in the measurement system monitors the star-shaped light spot image information in real time and transmits it to the image analysis and processing system. The image analysis and processing system, with its powerful analysis and processing capabilities, accurately determines the moment when the star-shaped light spot completely disappears, and records the air pressure value displayed by the air pressure detection device at this time. The air pressure value is the air pressure value inside the vacuum glass, thereby providing indispensable key data for the subsequent calculation of the heat transfer coefficient of the vacuum glass based on this air pressure value. The various parts of the entire measurement device work closely together to achieve accurate and efficient measurement of the heat transfer coefficient of the vacuum glass, overcome many shortcomings of traditional measurement methods, and effectively solve the problem that the existing detection method is difficult to accurately determine the critical point.

[0034] As a further technical solution of the device for measuring the heat transfer coefficient of vacuum glass, the light source system includes a light source, an incident light channel, a polarizing polarizer and a fixing flange;

[0035] The incident light channel is connected to the interior of the vacuum chamber and is fixedly connected to the wall of the vacuum chamber through the fixing flange. The polarizing plate is sealed and connected to the entrance of the incident light channel. The light emitted by the light source passes through the polarizing plate to form a uniform polarized light field on one side of the vacuum glass to be inspected.

[0036] In this scheme, the light source, as the source of light, provides basic energy for the entire measurement process. The incident light channel is connected to the interior of the vacuum chamber, guiding the light into the chamber to ensure that the light can accurately irradiate the vacuum glass to be tested. At the same time, it is fixed to the wall of the vacuum chamber through a fixed flange to ensure the stability and sealing of the structure. The polarizing polarizer is sealed and connected to the entrance of the incident light channel. It can convert the natural light emitted by the light source into polarized light. The uniform polarized light field is crucial for the subsequent generation of specific optical phenomena on the vacuum glass to be tested. The appearance and change of the light spot are related to the internal air pressure state of the vacuum glass, which provides a visual and monitorable basis for accurately judging the relevant performance of the vacuum glass, helping to improve the accuracy and reliability of the measurement and ensure the effective operation of the entire measurement device.

[0037] As a further technical solution of the device for measuring the heat transfer coefficient of vacuum glass, the measuring system further includes an observation window and an analyzing polarizer;

[0038] The observation window is connected to the interior of the vacuum chamber and is fixedly connected to the wall of the vacuum chamber through the fixing flange. The polarizing plate is sealed and connected to the exit of the observation window. The placement direction of the vacuum glass to be inspected is perpendicular to the incident light channel and the axial direction of the observation window.

[0039] In this scheme, the observation window is connected to the inside of the vacuum chamber, providing a channel for the inspector or the image acquisition device to observe the state of the vacuum glass in the vacuum chamber. It is fixed to the wall of the chamber through a fixed flange, which ensures the stability and sealing of the structure and prevents the air pressure leakage in the chamber from affecting the measurement. The polarizer is sealed and connected to the exit of the observation window. It works with the polarizer to detect the polarization state of the light after passing through the vacuum glass. Since the placement direction of the vacuum glass to be detected is perpendicular to the incident light channel and the axis of the observation window, this layout ensures that the light can pass through the vacuum glass vertically. After the star-shaped light spot is formed at the support column, it can accurately reflect the characteristic changes of the light spot when passing through the polarizer. During the vacuuming process, the changes of the star-shaped light spot can be clearly observed through the polarizer, especially when the key phenomenon of the light spot disappears, it can be captured in time and accurately, thereby providing a reliable basis for accurately judging the moment of pressure balance inside and outside the vacuum glass, and then determining the internal air pressure value of the vacuum glass, laying the foundation for the final accurate calculation of the heat transfer coefficient of the vacuum glass.

[0040] As a further technical solution of the device for measuring the heat transfer coefficient of vacuum glass, the measuring system also includes a calibration device, which stores vacuum glass sample data with known heat transfer coefficients. When the image analysis and processing system obtains the heat transfer coefficient of the vacuum glass through calculation, the calibration device calibrates and corrects the calculated heat transfer coefficient of the vacuum glass through the known heat transfer coefficient, and automatically fits the measurement results.

[0041] In this solution, the data of the vacuum glass sample with known heat transfer coefficient stored in the calibration device provides a reliable reference standard for the accuracy of the measurement results. After the image analysis and processing system calculates the heat transfer coefficient of the vacuum glass, the calibration device can use the stored data to calibrate and correct the calculated results. By comparing the heat transfer coefficient of the known sample with the coefficient obtained by measurement calculation, the measurement results are automatically fitted, thereby effectively reducing the errors that may occur during the measurement process. This process not only improves the accuracy of a single measurement, but also enhances the repeatability and reliability of the measurement results. In practical applications, there may be certain performance differences between vacuum glass from different batches or under different production conditions. The existence of the calibration device can make the measurement results closer to the actual heat transfer performance of the vacuum glass, and provide more accurate data support for the quality assessment, product development and application of vacuum glass in the fields of construction, etc., ensuring that the entire measurement device and method can obtain more accurate and reliable measurement results in different scenarios.

[0042] As a further technical solution of the device for measuring the heat transfer coefficient of vacuum glass, the cavity wall of the vacuum chamber is subjected to anti-reflection treatment.

[0043] In this scheme, the light will be reflected multiple times in the chamber. If the cavity wall is not treated, these reflected lights will interfere with each other, affecting the uniformity and stability of the polarized light field formed by the light on the vacuum glass, and then interfering with the observation and detection of the stress spot on the vacuum glass. Anti-reflection treatment can effectively reduce the reflection of light on the cavity wall, so that the light is more concentrated in the optical path of the vacuum glass and its related optical elements, improve the efficiency of light utilization, ensure the formation of a clear, stable and uniform polarized light field, so as to more accurately observe the star-shaped light spot formed at the support column and its changes. This helps to accurately determine the moment when the stress spot disappears, thereby improving the accuracy of the measurement of the internal air pressure value of the vacuum glass, and ultimately ensuring the accuracy of the calculation results of the heat transfer coefficient of the vacuum glass. At the same time, anti-reflection treatment is also conducive to improving the quality of the image collected by the image acquisition device, reducing the problems of image blur and noise caused by the interference of reflected light, so that the image analysis and processing system can more accurately analyze the change of the light spot, improve the reliability and stability of the entire measurement device and method, and provide a more favorable optical environment for the accurate measurement of the heat transfer coefficient of the vacuum glass.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] 1. The present invention uses an image acquisition device to image the stress spot on the image analysis and processing system. The image analysis system can accurately distinguish and judge the moment when the stress spot disappears. Compared with the existing technology, it is very convenient to determine this critical point, which greatly improves the measurement accuracy;

[0046] 2. The present invention measures the air pressure inside and outside the vacuum glass to be tested, which is completely unaffected by the ambient temperature and has good measurement repeatability. At the same time, by reasonably designing the volume of the vacuum cavity and using a high-power vacuum pumping system, the closed chamber can be quickly evacuated. In principle, the measurement can be completed within a few minutes, greatly shortening the measurement time.

[0047] 3. The calibration device in the measuring device of the present invention can store the data of vacuum glass samples with known heat transfer coefficients, and automatically fit the measurement results by calibrating and correcting them with the calculated heat transfer coefficients of the vacuum glass, thereby further improving the measurement accuracy and repeatability, making the measurement results more reliable, and providing a stronger guarantee for the quality control and performance evaluation of the vacuum glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0049] Figure 1 A simplified structural diagram of a device for measuring heat transfer coefficient of vacuum glass provided by the present invention;

[0050] Figure 2 This is a schematic diagram of the detection principle of the prior art;

[0051] Figure 3 It is the detection principle diagram of the present invention.

[0052] Marks and corresponding parts names in the attached drawings:

[0053] 1-vacuum chamber, 2-vacuum glass to be detected, 3-light source, 4-incident light channel, 5-polarizing polarizer, 6-fixing flange, 7-observation window, 8-polarizing polarizer, 9-vacuuming pipeline, 10-air pressure detection device, 11-vacuuming system, 12-image acquisition device, 13-image analysis and processing system, 14-upper glass, 15-lower glass, 16-support column, 17-incident light ray 1, 18-incident light ray 2, 19-star-shaped light spot. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0055] Example 1

[0056] According to the principle of photoelasticity, photoelastic materials will produce temporary birefringence under the action of external forces. This phenomenon can be observed through special instruments. Photoelasticity is a basic method of experimental stress analysis and has been widely used in the detection of automotive glass, tempered glass, etc.; when this material produces stress under the influence of the outside world, it will cause the polarized light passing through it to produce a special birefringence phenomenon; when the stress is released, this birefringence phenomenon will disappear; in this force model, interference fringes caused by the birefringence effect can be observed in the polarized light field.

[0057] Vacuum glass is a kind of stress glass. Because it is in a vacuum state, its air pressure is about 0.01~0.1Pa, which is about one millionth of the external atmospheric pressure. Under such a pressure difference, uneven stress concentration will be formed inside the vacuum glass. A matrix of 16 support columns is arranged at a fixed interval inside the vacuum glass. The support columns 16 form a support with the inner surface of the vacuum glass, which affects the stress distribution of the vacuum glass in a certain pattern. In the polarized light field, Figure 3 As shown, regularly distributed star-shaped light spots 19 can be seen on the side of the vacuum glass opposite to the light source, and their distribution is the same as the arrangement of the support columns 16. When the atmospheric pressure difference on both sides of the vacuum glass disappears, the stress is also released, and the star-shaped light spots 19 disappear. Accordingly, this embodiment 1 provides a method for measuring the heat transfer coefficient of vacuum glass, including the following steps:

[0058] Step 1: Place the vacuum glass 2 to be tested in the vacuum chamber 1. The vacuum chamber 1 is provided with a vacuum pumping system 11 and an air pressure detection device 10. The air pressure detection device 10 can display the air pressure value of the vacuum chamber 1 in real time.

[0059] Specifically, firstly, a comprehensive inspection is carried out on the vacuum chamber 1 to ensure that its structure is intact, the interior is clean and there is no risk of air leakage, and at the same time, it is confirmed that the vacuum system 11 and the air pressure detection device 10 are installed correctly and are tightly connected; then, the vacuum glass 2 to be detected is placed steadily at the designated position in the vacuum chamber 1, and any damage to the glass is strictly avoided during the placement process, and its placement direction is accurately adjusted with the help of positioning marks or auxiliary clamps, so that it is strictly perpendicular to the subsequent incident light channel 4 and the observation window 7 axis; after the placement is completed, the equipment connection status is carefully checked again to ensure that there is no risk of looseness or leakage, and then the air pressure detection device 10 is turned on to closely observe whether it starts normally and accurately displays the initial air pressure value in the vacuum chamber 1. If the display is abnormal, the relevant components of the air pressure detection device are immediately checked to eliminate the fault, thereby laying a solid foundation for the smooth implementation of subsequent measurement operations.

[0060] Step 2: forming a uniform polarized light field in the vacuum chamber 1, the direction of which is perpendicular to the placement direction of the vacuum glass 2 to be tested, so that the vacuum glass 2 to be tested forms a star-shaped light spot 19 at the support column 16;

[0061] Specifically, first, the light source system is turned on to make the light source 3 emit light, and the light passes through the polarizing polarizer 5 to convert natural light into polarized light, and the polarized light enters the vacuum chamber 1 through the incident light channel 4. The polarized light entering the chamber forms a uniform polarized light field inside, and its direction is perpendicular to the vacuum glass 2 to be inspected that has been placed and is perpendicular to the incident light channel 4. At this time, due to the particularity of the stress distribution at the support column 16 inside the vacuum glass, under the action of the polarized light field, the light undergoes optical phenomena such as refraction and interference at the support column 16, thereby forming a star-shaped light spot 19.

[0062] Step 3: evacuate the vacuum chamber through the vacuum pumping system, detect the star-shaped light spot through the polarizer on the side of the vacuum glass to be detected opposite to the light source, stop the vacuum pumping operation when the star-shaped light spot disappears, and record the air pressure value P displayed by the air pressure detection device at this time;

[0063] Specifically, first start the vacuum pumping system 11 to start the vacuum chamber 1 to evacuate the air. The evacuation process needs to be stable and continuous. While evacuating the air, pay close attention to the situation on the side opposite to the light source 3 of the vacuum glass 2 to be detected. The polarizer 8 here will detect the light passing through the vacuum glass. As the air pressure in the chamber gradually decreases, the pressure difference between the inside and outside of the vacuum glass continues to decrease, the stress state at the support column 16 also changes accordingly, and the brightness and shape of the star-shaped light spot 19 begin to change. Continue to observe the changes in the light spot. When the star-shaped light spot 19 disappears completely, stop the vacuum pumping operation immediately. This operation is quick and accurate, and avoids inaccurate measurements caused by excessive vacuum pumping. At the same time, quickly record the air pressure value P displayed by the air pressure detection device at this time. This air pressure value is the air pressure value inside the vacuum glass.

[0064] Step 4: Calculate the heat transfer coefficient of vacuum glass based on the obtained air pressure value P.

[0065] Specifically, the residual gas thermal conductivity is first calculated based on the recorded gas pressure value P, according to the formula C 气 =0.6P to get the result. Then get the thermal conductivity of the outer glass plate C1, the outer glass plate is the lower glass 15, the thermal conductivity of the inner glass plate C2, the inner glass plate is the upper glass 14, the two constants C1 and C2 can be obtained by querying the relevant technical parameters of the glass material, and calculate the thermal conductivity of the vacuum layer C' 真空 , the C' 真空 =C 辐射 +C 支 +C 气 , where the radiation thermal conductivity C 辐射 Calculated according to the following formula: σ is the Stefan-Boltzmann constant, σ = 5.67×10-8W / (m2·K4), T m为The average absolute temperature K of the gas spacer layer (can be obtained by measurement or estimation), ε1, ε2 are the average temperature T of the two glass surfaces in the spacer layer m Corrected emissivity under . Thermal conductivity of support C 支 According to the thermal conductivity of glass λg (constant), support height h (measurable), support column and glass contact area radius a (measurable), support array spacing b (measurable) and support column thermal conductivity λz (constant), the formula Calculate. Then calculate the thermal conductivity of vacuum glass C 真空 , the thermal conductivity of the outer glass plate C1, the thermal conductivity of the inner glass plate C2 and the thermal conductivity of the vacuum layer C' 真空 Substitute into the formula Finally, the inner surface heat transfer coefficient C 内 (constant), external surface heat transfer coefficient C 外 (constant) and the calculated thermal conductivity of vacuum glass C 真空 Substitute the U value calculation formula of vacuum glass heat transfer coefficient into Thus the heat transfer coefficient of vacuum glass is obtained.

[0066] In this embodiment, since the star-shaped light spot 19 only occurs at the position corresponding to the support column 16, it has nothing to do with the overall shape of the glass. Because the external pressure of the vacuum glass is greater than the internal pressure, the glass plate presses the support column 16, so a bright star-shaped light spot 19 is formed at the support column 16. When the pressure inside the vacuum chamber 1 and the vacuum glass is equal, the glass no longer squeezes the support column 16, and the star-shaped light spot 19 disappears immediately. When the air pressure in the vacuum chamber 1 continues to decrease and is lower than the air pressure inside the vacuum glass, the glass will not squeeze the support column 16, and the star-shaped light spot 19 will not appear again. Therefore, it is very convenient to determine this critical point, that is, the actual value of the air pressure inside the vacuum glass can be obtained without destroying the vacuum glass, and then the calculation method can be used to obtain the thermal conductivity of the residual gas in the vacuum glass, and then the specific value of the heat transfer coefficient of the vacuum glass can be obtained.

[0067] Therefore, this embodiment can achieve efficient and accurate measurement of the heat transfer coefficient of vacuum glass, and is completely unaffected by the ambient temperature, thus meeting the urgent need for accurate measurement of the heat transfer coefficient in the field of vacuum glass production and testing.

[0068] Example 2

[0069] This embodiment 2 provides a vacuum glass heat transfer coefficient measurement device based on the measurement method of embodiment 1. Figure 1 As shown, it includes a vacuum chamber 1, a light source system and a measurement system;

[0070] Among them, the interior of the vacuum chamber 1 is provided with a closed cavity for accommodating the vacuum glass 2 to be detected, and the cavity is connected with the air pressure detection device 10 and the vacuum system 11 through the vacuum pipeline 9. The air pressure measuring device 10 can display the air pressure value in the chamber in real time, and the vacuum system 11 can vacuum the cavity. In order to increase the vacuum speed, in some embodiments, the cavity size of the vacuum chamber 1 can be processed to be slightly larger than the size of the vacuum glass 2 to be detected.

[0071] Among them, the light source system forms a polarized light field on one side of the vacuum glass 2 to be detected, so that the vacuum glass 2 to be detected forms a star-shaped light spot 19 at the support column 16; specifically, the light source system includes a light source 3, an incident light channel 4, a polarizing polarizer 5 and a fixing flange 6, the incident light channel 4 is connected to the interior of the vacuum chamber 1, and is fixedly connected to the outer wall of the vacuum chamber 1 through the fixing flange 6, and the polarizing polarizer 5 is sealed and connected to the entrance of the incident light channel 4, and the light emitted by the light source 3 passes through the polarizing polarizer 5 to form a uniform polarized light field on one side of the vacuum glass 2 to be detected.

[0072] At the same time, the measuring system is on the other side of the vacuum glass 2 to be tested, and the measuring system includes an observation window 7, an analyzer polarizer 8, an image acquisition device 12 and an image analysis and processing system 13. The observation window 7 is connected to the interior of the vacuum chamber 1 and is also fixedly connected to the wall of the vacuum chamber 1 through a fixing flange 6. The analyzer polarizer 8 is sealed and connected to the exit of the observation window 7. The placement direction of the vacuum glass 2 to be tested is perpendicular to the axial direction of the incident light channel 4 and the observation window 7. Figure 3 As shown, the light source 3 is turned on, and the parallel light forms a uniform polarized light field after passing through the polarizing plate 5, and is vertically irradiated to one side of the vacuum glass 2 to be detected. After the polarized light passes through the vacuum glass 2 to be detected, it is affected by the vacuum glass 2 to be detected and refracted. Through the side of the vacuum glass 2 to be detected opposite to the light source 3, the star-shaped light spots 19 arranged at intervals on the vacuum glass 2 to be detected can be observed through the polarizing plate 8. The image acquisition device 12 includes but is not limited to a high-resolution CCD probe, etc., which can monitor the image information of the star-shaped light spots 19 in real time and transmit the image information to the image acquisition device 12. The image is transmitted to the image analysis and processing system 13. The image analysis system 13 can perform a detailed analysis and comparison on the star-shaped light spot 19. When the image analysis and processing system 13 determines that the star-shaped light spot 19 has completely disappeared, the image analysis and processing system 13 records the air pressure value displayed by the air pressure detection device 10 at this moment. This air pressure value is the air pressure value inside the vacuum glass 2 to be detected. After obtaining the air pressure value inside the vacuum glass 2 to be detected, the calculation module in the image analysis and processing system 13 can be used to obtain the thermal conductivity of the residual gas in the vacuum glass, and then the specific value of the heat transfer coefficient of the vacuum glass can be obtained.

[0073] Example 3

[0074] This embodiment 3 provides another vacuum glass heat transfer coefficient measuring device based on the technical solution of embodiment 2, such as Figure 1 As shown, the measurement system also includes a calibration device, which stores vacuum glass sample data with known heat transfer coefficients. When the image analysis and processing system 13 obtains the vacuum glass heat transfer coefficient through calculation, the calibration device calibrates and corrects the calculated vacuum glass heat transfer coefficient through the known heat transfer coefficient, and automatically fits the measurement results, thereby effectively reducing errors that may occur during the measurement process and making the measurement results more accurate.

[0075] At the same time, in order to reduce the reflection of light in the vacuum chamber 1 and avoid affecting the imaging effect, the cavity wall of the vacuum chamber 1 is subjected to anti-reflection treatment, such as blackening treatment.

[0076] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring the heat transfer coefficient of vacuum glass, characterized in that: The steps include: Step 1: placing the vacuum glass (2) to be tested in a vacuum chamber (1), wherein the vacuum chamber (1) is provided with a vacuum pumping system (11) and an air pressure detection device (10), wherein the air pressure detection device (10) can display the air pressure value of the vacuum chamber (1) in real time; Step 2: forming a uniform polarized light field in the vacuum chamber (1), wherein the direction of the polarized light field is perpendicular to the placement direction of the vacuum glass (2) to be tested, so that the vacuum glass (2) to be tested forms a star-shaped light spot (19) at the support column (16); Step 3: evacuating the vacuum chamber (1) through the vacuum pumping system (11), detecting the star-shaped light spot (19) through a polarizing plate (8) on the side of the vacuum glass (2) to be detected opposite to the light source, and stopping the vacuum pumping operation when the star-shaped light spot (19) disappears, and recording the air pressure value P displayed by the air pressure detection device (10) at this time; Step 4: Calculate the heat transfer coefficient of vacuum glass based on the obtained air pressure value P.

2. A method for measuring heat transfer coefficient of vacuum glass according to claim 1, characterized in that: The air pressure value P is the internal air pressure value of the vacuum glass (2) to be tested.

3. A method for measuring heat transfer coefficient of vacuum glass according to claim 1, characterized in that: The U value of the heat transfer coefficient of vacuum glass can be calculated as follows: Among them, C 内 is the inner surface heat transfer coefficient, C 外 is the external surface heat transfer coefficient, C 真空 Thermal conductivity of vacuum glass.

4. A method for measuring heat transfer coefficient of vacuum glass according to claim 3, characterized in that: The thermal conductivity of the vacuum glass is calculated as follows: C1 is the thermal conductivity of the outer glass plate, C2 is the thermal conductivity of the inner glass plate, C' 真空 is the thermal conductivity of the vacuum layer, which is calculated by the following formula: C' 真空 =C 辐射 +C 支 +C 气 .

5. A method for measuring heat transfer coefficient of vacuum glass according to claim 4, characterized in that: The radiation thermal conductivity is calculated as follows: σ is the Stefan-Boltzmann constant, σ = 5.67×10-8W / (m2·K4), T m为 The average absolute temperature of the gas spacer is K, and ε1 and ε2 are the average temperature of the two glass surfaces in the spacer at T m Corrected radiance under ; The thermal conductivity of the support is calculated as follows: λg is the thermal conductivity of glass [W / (m·K)], h is the height of the support (m), a is the radius of the contact area between the support column (16) and the glass (m), b is the support array spacing (m), and λz is the thermal conductivity of the support column (16) [W / (m·K)]; The residual gas thermal conductivity is calculated as follows: C 气 =0.6P。 6. A device for measuring heat transfer coefficient of vacuum glass, characterized in that: A method for measuring heat transfer coefficient of vacuum glass as claimed in any one of claims 1 to 5 is adopted, comprising: A vacuum chamber (1), wherein a cavity for accommodating the vacuum glass (2) to be tested is arranged inside the vacuum chamber (1), and the cavity is connected to an air pressure detection device (10) and a vacuum pumping system (11); A light source system, wherein the light source system forms a polarized light field on one side of the vacuum glass (2) to be inspected, so that the vacuum glass (2) to be inspected forms a star-shaped light spot (19) at a support column (16); A measuring system, the measuring system being located on the other side of the vacuum glass (2) to be detected, wherein the measuring system comprises an image acquisition device (12) and an image analysis and processing system (13), the image acquisition device (12) monitoring the image information of the star-shaped light spot (19) in real time, and transmitting the image information to the image analysis and processing system (13), and when the image analysis and processing system (13) determines that the star-shaped light spot (19) has completely disappeared, the image analysis and processing system (13) records the air pressure value displayed by the air pressure detection device (10) at this moment.

7. The device for measuring heat transfer coefficient of vacuum glass according to claim 6, characterized in that: The light source system comprises a light source (3), an incident light channel (4), a polarizing polarizer (5) and a fixing flange (6); The incident light channel (4) is connected to the interior of the vacuum chamber (1) and is fixedly connected to the wall of the vacuum chamber (1) via the fixing flange (6); the polarizing plate (5) is sealed and connected to the entrance of the incident light channel (4); the light emitted by the light source (3) passes through the polarizing plate (5) to form a uniform polarized light field on one side of the vacuum glass (2) to be inspected.

8. The device for measuring heat transfer coefficient of vacuum glass according to claim 7, characterized in that: The measuring system further comprises an observation window (7) and an analyzing polarizer (8); The observation window (7) is in communication with the interior of the vacuum chamber (1) and is fixedly connected to the wall of the vacuum chamber (1) via the fixing flange (6); the polarizing plate (8) is sealed and connected to the exit of the observation window (7); and the placement direction of the vacuum glass (2) to be inspected is perpendicular to the axial direction of the incident light channel (4) and the observation window (7).

9. The device for measuring heat transfer coefficient of vacuum glass according to claim 6, characterized in that: The measurement system also includes a calibration device, which stores vacuum glass sample data with known heat transfer coefficients. When the image analysis and processing system (13) obtains the vacuum glass heat transfer coefficient through calculation, the calibration device calibrates and corrects the calculated vacuum glass heat transfer coefficient through the known heat transfer coefficient, and automatically fits the measurement result.

10. The device for measuring heat transfer coefficient of vacuum glass according to claim 6, characterized in that: The cavity wall surface of the vacuum chamber (1) is subjected to anti-reflection treatment.

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