Rapid evaluation method and system for emissivity of sheet material

Abstract

The invention discloses a rapid evaluation method and system for emissivity of a sheet material, and belongs to the technical field of thermophysical property measurement of materials, the basic principle of the rapid evaluation method is that the sheet material is heated to a certain temperature by using a flat electric heater, and the upper limit temperature and the lower limit temperature of the sheet material are measured by using a thermocouple; a thermal infrared imager is used for shooting a thermal image of the sheet material, the average temperature of the thermal image is aligned with the upper limit temperature and the lower limit temperature of the sheet material by adjusting the emissivity of the material in thermal infrared imager software, and therefore the emissivity range of the sheet material under the temperature condition is obtained. The method has the following advantages: (1) complex and expensive instruments and equipment are not needed, the operation is simple, and the practicability is high; (2) the infrared emissivity range of the sheet material under vacuum or different atmosphere conditions can be rapidly evaluated; and (3) the emissivity range of the sheet material in a wide temperature range can be effectively evaluated.

Description

Technical Field

[0001] This invention relates to the field of material thermophysical property measurement technology, and in particular to a rapid evaluation method and system for the emissivity of thin sheet materials. Background Technology

[0002] Emissivity refers to the ratio of the thermal energy radiated by an object's surface to the thermal energy radiated by a blackbody (ideal radiator) at the same temperature. It is of great significance in fields such as coatings, remote sensing, meteorology, and materials science. Infrared thermal imaging is a convenient and rapid method for measuring temperature distribution, and the proper setting of emissivity is crucial to ensuring the accuracy of temperature measurements. Currently, the main methods for measuring emissivity include calorimetry, energy methods, reflectance methods, and multi-wavelength methods. Calorimetry offers high accuracy but requires a vacuum environment, is slow, the equipment is limited to laboratory use, and it cannot measure spectral or directional emissivity. Energy methods can simultaneously measure spectral emissivity and temperature but rely on a blackbody reference source, are susceptible to stray radiation, and the equipment is expensive and complex to operate. Reflectance methods have lower accuracy and are not suitable for specular reflective materials. Multi-wavelength methods require an emissivity-wavelength relationship model, are highly algorithm-dependent, have poor applicability to different materials, and lack a universal algorithm. Therefore, current emissivity measurements mainly rely on expensive proprietary equipment and complex model algorithms, causing significant inconvenience for non-professional laboratories using infrared thermal imagers to measure the temperature of different material systems. Summary of the Invention

[0003] To address the technical problems mentioned in the background section, this invention proposes a rapid evaluation method and system for the emissivity of sheet materials.

[0004] The technical solution of the present invention is as follows:

[0005] A rapid method for evaluating the emissivity of sheet materials includes the following steps:

[0006] S1, Test preparation: Place the test device inside a glove box, which provides a vacuum or specific atmosphere; the test device includes a thin sheet material, a flat electric heater, an infrared thermal imager, and thermocouples;

[0007] S2, heat the flat plate electric heater to the target temperature, and after stabilization, measure the temperature of the marked point on the heating plate through the thermocouple, which is the upper limit temperature T1;

[0008] S3, place the sheet material on the heating plate and cover the marked point. After the temperature stabilizes, measure the temperature on the upper surface of the sheet material at a position perpendicular to the marked point using the thermocouple. This temperature is the lower limit temperature T2.

[0009] S4, using the infrared thermal imager to capture a thermal image of the thin sheet material, the thermal image covering the area where the marked points are located;

[0010] S5, using thermal imaging analysis software, the region centered on the marked point is taken as the analysis region. The emissivity is adjusted so that the average temperature of the analysis region tends to be consistent with the upper limit temperature T1. The emissivity obtained is the lower limit emissivity A1 of the sheet material. The emissivity is adjusted so that the average temperature of the analysis region tends to be consistent with the lower limit temperature T2. The emissivity obtained is the upper limit emissivity A2 of the sheet material.

[0011] S6. Change the target temperature and repeat steps S2-S5 to obtain the emissivity range of the sheet material at different temperatures.

[0012] The specific atmosphere condition mentioned above is an oxygen-free atmosphere condition.

[0013] The infrared thermal imager is placed on an adjustable bracket to facilitate adjustment of its relative position to the sheet material.

[0014] The phrase "temperatures tending to be uniform" means that the temperature difference is no greater than 2°C.

[0015] The sheet material is a sheet of metal.

[0016] The thickness of the sheet material does not exceed 2 mm.

[0017] The analysis area is a circular region with a diameter of less than 10 mm centered on the marked point.

[0018] The heating rate of the flat plate electric heater is 5-10℃ / min, and the temperature stability criterion is that the temperature fluctuation within 10 minutes is ≤±1℃.

[0019] A system for implementing the above method includes:

[0020] Glove boxes that provide a vacuum / oxygen-free environment;

[0021] Flat-plate electric heater with temperature markings;

[0022] An infrared thermal imager with an adjustable bracket;

[0023] Thermocouple used to measure T1 / T2;

[0024] A computer terminal that runs thermal imaging analysis software.

[0025] The computer terminal is connected to the infrared thermal imager via wireless communication to transmit thermal image data in real time.

[0026] Beneficial effects:

[0027] The advantages of this invention are that it does not rely on complex and expensive emissivity measurement instruments and equipment. The upper and lower limits of the temperature of the upper surface of the thin sheet material can be determined using only a flat plate heater and a thermocouple. Then, the emissivity range can be derived using the software accompanying the thermal imager. This provides a simple and easy-to-use material emissivity evaluation method for non-professional laboratories using infrared thermal imagers. At the same time, this invention also has the advantages of a wide evaluation temperature range and controllable atmospheric conditions, making it widely applicable. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the emissivity range evaluation method under different temperature conditions according to the present invention.

[0029] Figure 2 This is a schematic diagram of a rapid evaluation system for the emissivity of sheet materials provided in an embodiment of the present invention.

[0030] In the diagram: 1. Glove box; 2. Infrared thermal imager; 3. Adjustable stand; 4. Flat plate heater; 5. K-type thermocouple; 6. Computer terminal. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0032] Example

[0033] Figure 1 The method for rapidly evaluating the emissivity of a thin sheet material, as shown, includes the following steps:

[0034] Step 1: Setting up the testing environment: Place the testing apparatus in the glove box beforehand, then start the vacuum system to achieve a chamber pressure of 1.1 mbar, a water content of 0.01 ppm, and an oxygen content of 0.01 ppm. Sample heating: Use a flat plate heater to heat the sample to the target temperature at a rate of 8℃ / min. After the temperature stabilizes, use a type K thermocouple to measure the temperature at a marked point on the heater plate. This temperature is the upper limit temperature T1 of the upper surface of the thin sheet material at that point.

[0035] Step 2: Place the sheet material at the marked point on the heater plate described in Step 1. After the temperature of the upper surface of the sheet material stabilizes, use the thermocouple described in Step 1 to measure the temperature at a position perpendicular to the marked point on the upper surface of the sheet material. This temperature is the lower limit temperature T2 of the upper surface of the sheet material at that point.

[0036] Step 3: Install the FLUKE thermal imager and its bracket, ensuring that its lens is perpendicular to the heater plate marking point described in Step 1, with a distance of 10cm. Establish a real-time communication connection between the thermal imager and the plate via Bluetooth. After the thermocouple measurement described in Step 1 is completed, remotely collect thermal image data covering the area where the marking point described in Step 1 is located.

[0037] Step 4: Using SmartView Classic 4.4 professional analysis software, import the raw thermal image acquired by the FLUKE thermal imager described in Step 2 into the computer workstation, and use the software's built-in circular selection tool to accurately delineate a circle with a diameter of less than 10mm centered on the marker point described in Step 1 as the analysis area.

[0038] Step 5: Adjust the emissivity parameters within the analysis area described in Step 4 to make its average temperature consistent with T1 described in Step 1. The resulting emissivity is the lower limit emissivity A1 of the sheet material. Adjust the emissivity parameters within the area to make its average temperature consistent with T2 described in Step 2. The resulting emissivity is the upper limit emissivity A2 of the sheet material. At this point, the emissivity range of the sheet material within the temperature range of T2 to T1 is A1 to A2. Repeat the above process by changing the target temperature to obtain the emissivity range of the sheet material at different temperatures. Table 1 shows the test results for the sheet foam metal.

[0039] Table 1

[0040]

[0041] like Figure 2As shown, this embodiment also provides a rapid evaluation system for the emissivity of sheet materials. This rapid evaluation system for the emissivity of sheet materials is used to implement the above-mentioned rapid evaluation method for the emissivity of sheet materials. Specifically, the rapid evaluation system for the emissivity of sheet materials includes a glove box 1, an infrared thermal imager 2, an adjustable bracket 3, a flat plate heater 4, a K-type thermocouple 5, and a computer terminal 6. The glove box 1 is adjustable for its box pressure, water content, and oxygen content. The lens of the infrared thermal imager 2 is perpendicular to the sheet material and is used to collect thermal image data. The adjustable bracket 3 is used to adjust the position of the infrared thermal imager 2 for focusing. The flat plate heater 4 is used to heat the sheet material. The K-type thermocouple 5 is used to measure the upper / lower limit temperature of the sheet material. The thermal imager data is processed on the computer terminal 6 to estimate the emissivity range of the material. To estimate the emissivity range of the sheet material, the upper temperature limit T1 is obtained by first measuring the temperature at a marked point on the flat plate heater 4 using a K-type thermocouple 5. Then, after the sheet material is placed at the marked point and its temperature stabilizes, the lower temperature limit T2 is obtained by measuring the temperature of the upper surface of the sheet material perpendicular to the marked point using the K-type thermocouple 5. Next, thermal image data of the marked point is acquired using an infrared thermal imager 2. Finally, thermal image analysis software is run on a computer terminal 6 to determine the emissivity range of the sheet material based on the upper and lower temperature limits. This rapid emissivity evaluation system for sheet materials enables the rapid evaluation of the emissivity of sheet materials using the above-mentioned method, providing a simple, easy-to-implement, and highly reliable method for estimating the emissivity range of sheet materials.

[0042] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily 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 this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A rapid method for evaluating the emissivity of a thin sheet material, characterized in that, Includes the following steps: S1, Test preparation: Place the test device inside a glove box, which provides a vacuum or specific atmosphere; the test device includes a thin sheet material, a flat electric heater, an infrared thermal imager, and thermocouples; S2, heat the flat plate electric heater to the target temperature, and after stabilization, measure the temperature of the marked point on the heating plate through the thermocouple, which is the upper limit temperature T1; S3, place the sheet material on the heating plate and cover the marked point. After the temperature stabilizes, measure the temperature on the upper surface of the sheet material at a position perpendicular to the marked point using the thermocouple. This temperature is the lower limit temperature T2. S4, using the infrared thermal imager to capture a thermal image of the sheet material, the thermal image covering the area where the marked points are located; S5, using thermal imaging analysis software, the region centered on the marked point is taken as the analysis region. The emissivity is adjusted so that the average temperature of the analysis region tends to be consistent with the upper limit temperature T1. The emissivity obtained is the lower limit emissivity A1 of the sheet material. The emissivity is adjusted so that the average temperature of the analysis region tends to be consistent with the lower limit temperature T2. The emissivity obtained is the upper limit emissivity A2 of the sheet material. S6. Change the target temperature and repeat steps S2-S5 to obtain the emissivity range of the sheet material at different temperatures.

2. The method according to claim 1, characterized in that, The specific atmospheric conditions are oxygen-free atmospheric conditions.

3. The method according to claim 1, characterized in that, The infrared thermal imager is placed on an adjustable bracket to facilitate adjustment of its relative position to the sheet material.

4. The method according to claim 1, characterized in that, The temperature tending to be uniform means that the temperature difference is no greater than 2℃.

5. The method according to claim 1, characterized in that, The sheet material is a sheet of metal.

6. The method according to claim 1, characterized in that, The thickness of the sheet material does not exceed 2 mm.

7. The method according to claim 1, characterized in that, The analysis area is a circular region with a diameter of less than 10 mm centered on the marked point.

8. The method according to claim 1, characterized in that: The heating rate of the flat plate electric heater is 5-10℃ / min, and the temperature stability criterion is that the temperature fluctuation within 10 minutes is ≤±1℃.

9. A system for implementing the method of any one of claims 1-8, characterized in that, include: Glove boxes that provide a vacuum / oxygen-free environment; Flat-plate electric heater with temperature markings; An infrared thermal imager with an adjustable bracket; Thermocouple used to measure T1 / T2; A computer terminal that runs thermal imaging analysis software.

10. The system according to claim 9, characterized in that, The computer terminal and the infrared thermal imager are connected wirelessly to transmit thermal image data in real time.

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