Method for detecting real temperature and emissivity of sample

Abstract

The invention relates to a method for detecting the real temperature and emissivity of a sample, belongs to the technical field of emissivity testing, and solves the problem of inaccurate temperature and emissivity detection results caused by the existing method. Comprising the following steps: calibrating a colorimetric thermometer, obtaining a light transmittance ratio # imgabs0 # of light with two wavelengths lambda1 and lambda2 of the colorimetric thermometer of a light path system, and obtaining a relational expression between the temperature measured by the colorimetric thermometer and the real temperature of the surface of a sample; and correcting according to the Planck theorem to obtain the real temperature (Tr) of the surface of the sample and the spectral emissivity curve epsilon (lambda, (Tr)) at the temperature. The method provided by the invention is helpful for improving the accuracy of temperature and spectral emissivity.

Description

Technical Field

[0001] The present invention relates to the technical field of emissivity testing of object surfaces, and particularly to a method for detecting the true temperature and emissivity of a sample. Background Art

[0002] The emissivity of an object surface refers to the ratio of the radiant energy of the object surface to the surface radiant energy of an ideal black body at the same temperature. Therefore, in the actual emissivity measurement process by the energy comparison method, it is necessary to accurately measure the temperature and radiant energy of the object surface, as well as the radiant energy of the ideal black body at the same temperature. In a high-temperature emissivity testing device using the energy comparison method, a Fourier spectrometer is commonly used to measure the spectral radiant energy of the sample surface; at the same time, a temperature sensor (such as a thermocouple, an optical thermometer, etc.) is used to measure the temperature of the sample surface, and then the spectral radiant energy of the ideal black body at the same temperature is obtained by sample temperature measurement (measured by a Fourier spectrometer after heating a standard black body source to the same temperature) or calculation (calculated using Planck's theorem); the spectral emissivity is obtained by comparing the radiant energy of the sample surface with the radiant energy of the black body. When the measured temperature of the sample surface exceeds 2000 °C, conventional thermocouples are difficult to meet the requirements of long-term stable temperature measurement. At this time, a high-temperature optical thermometer is commonly used to measure the temperature of the sample surface. High-temperature optical thermometers mainly include three categories: radiation thermometers, brightness thermometers, and colorimetric thermometers. Among them, when a radiation thermometer measures temperature, the total emissivity parameter of the material is required, when a brightness thermometer measures temperature, the spectral emissivity parameter of a specific wavelength is required, and when a colorimetric thermometer measures temperature, the ratio of the emissivities of two specific wavelengths is required. Moreover, the emissivity of the sample surface is exactly the parameter to be measured, and the emissivity, or the ratio of the emissivities of two specific wavelengths, may vary with temperature. Therefore, when an optical pyrometer is used to measure temperature in a high-temperature emissivity testing device, temperature measurement and emissivity measurement are coupled together, and it is impossible to solve any one component separately.

[0003] In existing high-temperature emissivity testing devices, when a colorimetric thermometer is used to measure temperature, the commonly used method is to assume that the ratio of the emissivities of two wavelengths of the specimen is a constant within the measured temperature range, so that the temperature can be obtained first and then the emissivity can be solved. However, when the temperature range of the measured sample is very wide and the ratio of the emissivities of two wavelengths changes significantly, the existing method will cause deviations in the results of temperature and emissivity. Summary of the Invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a method for detecting the true temperature and emissivity of a sample, so as to solve the problem that the existing method may cause inaccurate results in detecting temperature and emissivity.

[0005] On the one hand, an embodiment of the present invention provides a method for detecting the true temperature and emissivity of a sample, the method comprising:

[0006] (a) Calibrate the colorimetric thermometer to obtain the transmittance ratio of the light with two wavelengths λ1 and λ2 of the colorimetric thermometer in the optical path system of the emissivity test device. Among them, τ1 is the transmittance of the optical path system to the light with wavelength λ1, and τ2 is the transmittance of the optical path system to the light with wavelength λ2.

[0007] (b) Place the sample to be measured in the emissivity test device, heat it until the temperature reaches stability. According to Planck's theorem, the relationship between the temperature measured by the colorimetric thermometer and the true temperature of the sample surface is as shown in Equation (4).

[0008]

[0009] Among them, T r is the true temperature of the sample surface; T is the temperature directly measured by the colorimetric thermometer; λ1, λ2 are the two wavelengths of the colorimetric thermometer; ε(λ1, T r ) and ε(λ2, T r ) are the emissivities corresponding to the two wavelengths λ1 and λ2 at T r temperature respectively; c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K.

[0010] Rearrange Equation (4) to obtain Equation (5).

[0011]

[0012] Among them, T r is the true temperature of the sample surface; T is the temperature measured by the colorimetric thermometer; λ1, λ2 are the two wavelengths of the colorimetric thermometer; ε(λ1, T r ) and ε(λ2, T r ) are the emissivities corresponding to the two wavelengths λ1 and λ2 at T r degree respectively; c2 is the second radiation constant, 1.4388×10 -2 m·K.

[0013] (c) Assume as an initial constant, calculate (T r ) through Equation (5), and then obtain the spectral emissivity distribution curve ε(λ, (T r ));

[0014] (d) Correct the result of step (c) according to Planck's theorem.

[0015] Preferably, step (d) includes: using ε(λ1, T r ) and ε(λ2, T r ) obtained from the spectral emissivity distribution curve in step (c) to calculate Then substitute the obtained into Equation (5) for calculation, and repeat the iterative operation in this way until the obtained in the last iteration is similar to the obtained in the previous iteration. Then the (T r ) and ε(λ, (T r )) obtained in the last iteration are the true temperature of the sample surface and the spectral emissivity curve at this temperature, respectively.

[0016] Preferably, steps (c) to (d) include:

[0017] (c-1) Assume an initial and substitute it into Equation (5) to calculate (T r )1;

[0018] (c-2) Obtain the spectral emissivity distribution curve ε(λ, (T r )1)1 at the temperature of (T r )1;

[0019] (d-1) According to the spectral emissivity distribution curve ε(λ, (T r )1)1, extract the emissivity values ε(λ1)1 and ε(λ2)1 corresponding to λ1 and λ2, and compare the two to obtain

[0020] (d-2) Substitute m1 into Equation (5), and repeat steps (c-1), (c-2) and (d-1) i times to obtain (T r ) i , ε(λ, (T r ) i ) i and m i ; When m i and m i-1 meet the proximity requirement, the iterative operation ends. Then (T r ) i , ε(λ, (T r ) i ) i are the true temperature of the sample surface and the spectral emissivity curve at this temperature, respectively.

[0021] Preferably, in step (c-2), the obtaining of the spectral emissivity distribution curve ε(λ, (T r )1) at the temperature of (T r)1)1, including: calculating the distribution curve of the ideal blackbody radiation energy with respect to wavelength at temperature (T r )1, the distribution curve of the radiation energy on the surface of the sample measured by a spectrometer, dividing the radiation energy on the surface of the sample by the ideal blackbody radiation energy to obtain the spectral emissivity distribution curve ε(λ, (T r )1)1.

[0022] Preferably, the spectrometer is a Fourier spectrometer.

[0023] Preferably, in step (d-2), the proximity requirement is

[0024] Preferably, in step (a), a blackbody furnace is used to calibrate the colorimetric thermometer.

[0025] Preferably, the calibration using a blackbody furnace for the colorimetric thermometer includes:

[0026] Put a blackbody furnace in the emissivity test device, set the temperature to T bf , the emissivity of the blackbody at all wavelengths is 1. Therefore, the ratio of the emissivities at two wavelengths λ1 and λ2 in the colorimetric thermometer is 1, and the colorimetric thermometer directly measures the ratio of the radiation energies corresponding to λ1 and λ2 According to Planck's law, calculate the temperature T from Equation (1);

[0027]

[0028] where, c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; T is the temperature measured by the colorimetric thermometer; λ1, λ2 are the two wavelengths of the colorimetric thermometer;

[0029] The light transmission rates of the two wavelengths λ1 and λ2 of the colorimetric thermometer in the temperature measurement optical path system are τ1 and τ2 respectively, then the relationship between the temperature T and the true temperature T bf of the blackbody furnace is shown in Equation (2),

[0030]

[0031] where, c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; T is the temperature measured by the colorimetric thermometer; T bf$T$ is the true temperature of the blackbody furnace; $\lambda_1$ and $\lambda_2$ are the two wavelengths of the colorimetric thermometer; $\tau_1$ and $\tau_2$ are the light transmittance rates of the two wavelengths $\lambda_1$ and $\lambda_2$ of the colorimetric thermometer, respectively;

[0032] Rearranging Equation (2) gives Equation (3),

[0033]

[0034] Substitute the temperature $T$ directly measured by the colorimetric thermometer and the true temperature $T$ of the blackbody furnace bf into Equation (3), and the ratio of the light transmittance rates of the two wavelengths $\lambda_1$ and $\lambda_2$ of the colorimetric thermometer by the temperature measurement optical path system is obtained

[0035] Preferably, the position of the blackbody furnace in the emissivity test device is the same as the position where the sample is placed.

[0036] Preferably, in step (b), the heating includes: heating the sample at a constant power by manually adjusting the heating power of the power supply.

[0037] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0038] 1. In the existing method, it is considered that the ratio of the emissivities of two wavelengths is a fixed value within a certain temperature range. For example, it is 1 from 1000K - 1500K, and then 1 is substituted into the calculation of the specific temperature value and the spectral emissivity curve within this temperature range. However, when the temperature range of the sample to be measured is very wide and the ratio of the emissivities of the two wavelengths changes significantly, the existing method will cause deviations in the results of temperature and emissivity. The present invention corrects the above results according to Planck's theorem, thereby obtaining accurate temperature and spectral emissivity.

[0039] 2. The present invention believes that the ratio of the emissivities of two wavelengths is not fixed within a certain temperature range and may change at different temperatures. Therefore, first assume that the ratio of the emissivities of the two wavelengths is 1, and then perform iterative correction on the temperature and emissivity until the ratio of the emissivities converges to a certain value. When the measured temperature range is wide and the spectral emissivity of the sample changes violently with temperature and wavelength, the method of the present invention helps to improve the detection accuracy of temperature and spectral emissivity.

[0040] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the content specifically pointed out in the specification and the drawings. Description of the Drawings

[0041] The accompanying drawings are only for the purpose of showing specific embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference signs denote the same components.

[0042] Figure 1 It is a schematic structural diagram of a high-temperature emissivity test device;

[0043] Figure 2 It is the spectral energy distribution diagram obtained by measuring the radiation energy on the surface of the sample with a Fourier spectrometer in Example 1;

[0044] Figure 3 It is the spectral emissivity distribution curve of the graphite sheet in Example 1;

[0045] Figure 4 It is the spectral emissivity distribution curve of the graphite sheet in Comparative Example 1.

[0046] Reference Signs

[0047] 1 - Test platform; 16 - Vacuum chamber; 17 - Liquid nitrogen cooling inner liner; 161 - Diamond light-transmitting window; 162 - Diamond light-transmitting window; 2 - Colorimetric thermometer; 3 - Fourier spectrometer; 4 - Off-axis parabolic mirror; 5 - Plane mirror; 6 - Plane mirror; 7 - Off-axis parabolic mirror; 8 - Plane mirror; 9 - Plane mirror. Detailed Embodiments

[0048] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0049] On the one hand, the present invention provides a method for detecting the true temperature and emissivity of a sample, and the method includes:

[0050] (a) Calibrate the colorimetric thermometer to obtain the transmittance ratio of the light of two wavelengths λ1 and λ2 of the colorimetric thermometer in the optical path system of the emissivity test device where τ1 is the transmittance of the optical path system to the light with wavelength λ1, and τ2 is the transmittance of the optical path system to the light with wavelength λ2.

[0051] It should be noted that in the high-temperature emissivity test device, the sample and the heating device are placed in a vacuum chamber with a constant temperature on the side wall surface at the same time, and then the radiation energy on the surface of the sample is led out of the vacuum chamber by an optical mirror group and introduced into a Fourier spectrometer for radiation energy measurement, and at the same time introduced into a colorimetric thermometer for temperature measurement. The schematic structural diagram of the high-temperature emissivity test device is as Figure 1 shown. To ensure the accuracy of temperature measurement, it is necessary to calibrate the entire temperature measurement optical path and the colorimetric thermometer first.

[0052] Exemplarily, a blackbody furnace is used for calibration with a colorimetric thermometer.

[0053] Specifically, the calibration using a blackbody furnace with a colorimetric thermometer includes:

[0054] The two wavelengths of the colorimetric thermometer are λ1 and λ2 respectively, and the transmittances of the entire temperature measurement optical path system in the high-temperature emissivity test device for the light of these two wavelengths are τ1 and τ2 respectively. A blackbody furnace is placed in-situ in the emissivity test device, and the temperature is set to T bf , because the object to be measured is a blackbody, and the emissivity of a blackbody at all wavelengths is 1. Therefore, the ratio of the emissivities of the two wavelengths λ1 and λ2 in the colorimetric thermometer is 1, and the colorimetric thermometer directly measures the ratio of the radiation energies corresponding to λ1 and λ2 According to Planck's theorem, the temperature T is calculated from Equation (1);

[0055]

[0056] where, c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; T is the temperature measured by the colorimetric thermometer; λ1, λ2 are the two wavelengths of the colorimetric thermometer.

[0057] The light transmittances of the temperature measurement optical path system for the two wavelengths λ1 and λ2 of the colorimetric thermometer are τ1 and τ2 respectively, and τ1 and τ2 are not the same. Then the temperature T and the true temperature T of the blackbody furnace bf are not equal. The relationship between the temperature T and the true temperature T of the blackbody furnace bf is shown in Equation (2),

[0058]

[0059] c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; T is the temperature measured by the colorimetric thermometer; T bf is the true temperature of the blackbody furnace; λ1, λ2 are the two wavelengths of the colorimetric thermometer; τ1 and τ2 are the light transmittances of the two wavelengths λ1 and λ2 of the colorimetric thermometer respectively.

[0060] Rearranging Equation (2) gives Equation (3),

[0061]

[0062] The temperature T calculated from Equation (1) and the true temperature T of the blackbody furnace bfSubstituting into Equation (3), the transmittance ratio of the two wavelengths λ1 and λ2 of the temperature measurement optical path system for the colorimetric thermometer is obtained. The calibration is completed.

[0063] It can be understood that since there is energy loss when light radiation passes through the optical component, there is a transmission coefficient τ1 between E(λ1) and the true energy emitted by the blackbody furnace. The same is true for E(λ2). Therefore, the temperature T directly calculated by the colorimetric thermometer and the true temperature T of the blackbody bf do not necessarily be equal, and the relationship between the two is expressed by (3).

[0064] (b) After obtaining the temperature calibration procedure in step (a) After that, place the sample to be measured in the emissivity test device, heat the sample to be measured at a constant power by manually adjusting the heating power of the power supply and make the temperature reach stability. The colorimetric thermometer measures the temperature T (this temperature T represents the surface temperature of the sample directly measured by the colorimetric thermometer, which may be inconsistent with the true surface temperature T of the sample, and the true temperature T r is unknown and to be determined), and then obtain the spectral radiant energy of the ideal blackbody at this temperature according to Planck's theorem; measure the radiant energy of the sample surface with a Fourier spectrometer, and the ratio of the radiant energy of the sample surface to the blackbody radiant energy at the same temperature is the emissivity ε(λ, T). r According to Planck's theorem, the relationship between the temperature measured by the colorimetric thermometer and the true surface temperature of the sample is as shown in Equation (4).

[0065]

[0066]

[0067] where, T r is the true surface temperature of the sample, which is an unknown quantity to be determined; T is the temperature directly measured by the colorimetric thermometer; λ1, λ2 are the two wavelengths of the colorimetric thermometer; ε(λ1, T r ) and ε(λ2, T r ) are the emissivities corresponding to the two wavelengths λ1 and λ2 at temperature T r respectively; c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K;

[0068] Rearranging Equation (4), Equation (5) is obtained.

[0069]

[0070] where, T ris the true temperature of the sample surface; T is the temperature measured by the colorimetric thermometer; λ1 and λ2 are the two wavelengths of the colorimetric thermometer; ε(λ1, T r ) and ε(λ2, T r ) are the emissivities corresponding to the two wavelengths λ1 and λ2 at T r temperature respectively; c2 is the second radiation constant, 1.4388×10 -2 m·K;

[0071] In Equation (5), if the parameter is known, substituting m, and T into Equation (5) can obtain the true temperature T r of the sample. However, since ε(λ) is an unknown quantity to be determined, the parameter is also unknown. Therefore, the true temperature of the sample surface cannot be directly calculated. Therefore, the present invention performs iterative operations according to steps (c) and (d).

[0072] (c) Assuming as an initial constant, calculating (T r ) through Equation (5), and then obtaining the spectral emissivity distribution curve ε(λ, (T r ));

[0073] (d) Correcting the result of step (c) according to Planck's theorem.

[0074] Specifically, step (d) includes: using ε(λ1, T r ) and ε(λ2, T r ) in the spectral emissivity distribution curve obtained in step (c) to calculate Then substituting the obtained into Equation (5) for calculation, and repeating the iterative operation like this until the obtained in the last iteration is close to the obtained in the previous iteration. Then the (T r ) and ε(λ, (T r )) obtained in the last iteration are the true temperature of the sample surface and the spectral emissivity curve at this temperature respectively.

[0075] Specifically, steps (c) to (d) include:

[0076] (c-1) Assuming an initial and substituting it into Equation (5) to calculate (T r )1;

[0077] (c-2) Obtaining the spectral emissivity distribution curve ε(λ, (T r )1)1 at the temperature of (T r )1;

[0078] (d-1) According to the spectral emissivity distribution curve ε(λ,(T r )1)1, extract the emissivity values ε(λ1)1 and ε(λ2)1 corresponding to λ1 and λ2, and compare the two to obtain

[0079] (d-2) Substitute m1 into Equation (5), repeat steps (c-1), (c-2) and (d-1) i times, and respectively obtain (T r ) i , ε(λ,(T r ) i ) i and m i ; when m i and m i-1 meet the similar requirements, the iterative operation ends, then (T r ) i , ε(λ,(T r ) i ) i are respectively the true temperature of the sample surface and the spectral emissivity curve at this temperature.

[0080] It should be noted that in step (c-2), the obtaining of the spectral emissivity distribution curve ε(λ,(T r )1)1 at the temperature of (T r )1 includes: calculating the distribution curve of the radiation energy of an ideal blackbody at the temperature of (T r )1 with respect to wavelength by using Planck's theorem, measuring the radiation energy distribution curve of the sample surface with a spectrometer, and dividing the radiation energy distribution curve of the sample surface with respect to wavelength by the radiation energy distribution curve of the ideal blackbody to obtain the spectral emissivity distribution curve ε(λ,(T r )1)1.

[0081] Exemplarily, the spectrometer is a Fourier spectrometer.

[0082] Exemplarily, in step (d-2), the similar requirement is

[0083] Compared with the prior art, the present invention uses an iterative correction method, which can be independent of the assumption that the ratio of the emissivities in two bands is a constant when using a colorimetric thermometer to measure temperature in the assumed temperature range of the specimen in the existing method. When the measured temperature range is very wide and the spectral emissivity of the sample varies greatly with temperature and wavelength, the method of the present invention helps to improve the accuracy of temperature and spectral emissivity.

[0084] Next, the method for detecting the true temperature and emissivity of a sample according to the present invention will be further described by specific examples.

[0085] Example 1

[0086] A method for detecting the true temperature and emissivity of a sample, the method comprising:

[0087] (a) Calibrating a colorimetric thermometer to obtain the transmittance ratio of light at two wavelengths λ1 and λ2 of the colorimetric thermometer in the optical path system where τ1 is the transmittance of light with wavelength λ1 in the optical path system, and τ2 is the transmittance of light with wavelength λ2 in the optical path system.

[0088] In this example, the two wavelengths λ1 and λ2 of the colorimetric thermometer are 3 μm and 5 μm respectively. A blackbody furnace is placed in situ in the emissivity test device, and the temperature is set to T bf = 1500 K. Start heating to raise the blackbody furnace to the set temperature and keep it at a constant temperature. The temperature directly measured by the colorimetric thermometer is T = 1486 K. This temperature value is calculated from Equation (1) after the thermometer measures the energies E(λ1) and E(λ2) at two wavelengths:

[0089]

[0090] where c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; T is the temperature measured by the colorimetric thermometer; λ1, λ2 are the two wavelengths of the colorimetric thermometer.

[0091] There is a deviation between the temperature of 1486 K measured by the colorimetric thermometer and the true temperature of 1500 K of the blackbody furnace. This is because the true radiation energy of the blackbody furnace is attenuated to a certain extent when passing through the optical components before entering the thermometer and being detected by it. There is a loss coefficient between the true radiation energy of the blackbody and the energy detected by the thermometer. Considering the influence of the loss coefficient (i.e., the transmittance ratio defined in the present invention), the relationship between the true temperature T bf of the blackbody furnace and the thermometer reading T is shown in Equation (2),

[0092]

[0093] Rearranging Equation (2) gives Equation (3),

[0094]

[0095] Substitute the temperature T = 1486 K and the true temperature T bf = 1500 K of the blackbody furnace into Equation (3) to obtain the transmittance ratio of light at two wavelengths λ1 and λ2 of the colorimetric thermometer in the temperature measurement optical path system The calibration is completed.

[0096] (b) After obtaining the temperature calibration procedure in step (a), put the graphite sample to be measured into the emissivity test device, heat the sample at a constant power by manually adjusting the heating power of the power supply. When the reading of the colorimetric thermometer reaches stability, the temperature display is T = 1585K. At this time, the true temperature of the sample surface is T r (this temperature is unknown and to be determined). Then, according to Planck's theorem, obtain the spectral radiant energy of the ideal blackbody at this temperature T r ; measure the radiant energy on the sample surface with a Fourier spectrometer, and the obtained spectral energy distribution diagram is as Figure 2 shown. The ratio of the radiant energy on the sample surface to the blackbody radiant energy at the same temperature is the emissivity ε(λ, T).

[0097] According to Planck's theorem, the relationship between the temperature measured by the colorimetric thermometer and the true temperature of the sample surface is as shown in Equation (4),

[0098]

[0099] where, T r is the true temperature of the sample surface; T is the temperature measured by the colorimetric thermometer; ε(λ1, T r ) and ε(λ2, T r ) are the emissivities corresponding to the two wavelengths λ1 and λ2 at the temperature T r respectively; c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K;

[0100] Rearrange Equation (4) to obtain Equation (5),

[0101]

[0102] (c) to (d): (c-1) Assume an initial Then substitute T = 1585K into Equation (5) and calculate to get (T r )1 = 1601K;

[0103] (c-2) Use Planck's theorem to calculate the spectral radiant energy of the ideal blackbody at the temperature (T r )1, measure the radiant energy on the sample surface with a Fourier spectrometer, divide the radiant energy on the sample surface by the spectral radiant energy of the ideal blackbody, and obtain the spectral emissivity distribution curve ε(λ, (T r )1)1;

[0104] (d-1) According to the spectral emissivity curve ε(λ, (T r ))1, extract the emissivity values ε(λ1)1 and ε(λ2)1 corresponding to λ1 and λ2, and compare the two to obtain

[0105] (d-2) Substitute m1 into Equation (5), and repeat steps (c-1), (c-2), and (d-1) to obtain (T r )2 = 1565K, m2 = 1.03514. Repeat the above steps i times to obtain (T r ) i , ε(λ, (T r )) i ) i and m i ; when m i and m i-1 meet the convergence requirement , the iterative calculation ends, then (T r ) i , ε(λ, (T r )) i ) i are the true temperature of the sample surface and the spectral emissivity curve at this temperature, respectively. In this embodiment, after multiple rounds of iterative calculations, the calculated m i-1 = 1.06940, m i = 1.06978, and at this time (T r ) i = 1500.5K. Use (T r ) i = 1500.5K to calculate the spectral emissivity as shown in Figure 3 .

[0106] Comparative Example 1

[0107] Use the existing method to calculate the true temperature of the sample surface and the spectral emissivity curve at this temperature. The specific steps are as follows:

[0108] (1) Calibrate the temperature measurement optical path according to step (a) of Example 1 to obtain the transmittance ratio of the optical system

[0109] (2) Measure the graphite sheet. The direct reading of the colorimetric thermometer is T = 1585K, and the spectral radiant energy distribution of the sample measured by the Fourier spectrometer is as shown in Figure 2 . Use T = 1585K and Equation (5) to calculate the sample temperature T r = 1601K. In this process, it is defaulted that the ratio m of the emissivities at two wavelengths λ1 and λ2 is 1.

[0110] (3) According to step (c-2) in Example 1, substitute T r = 1601K into the calculation to obtain the spectral emissivity distribution curve of the sample, as Figure 4 shown.

[0111] Result Analysis

[0112] In Comparative Example 1, calculate according to the emissivities ε(λ1) and ε(λ2) corresponding to the two wavelengths of λ1 = 3μm and λ2 = 5μm Compared with m = 1 in step (2) of Comparative Example 1, the difference between the two is 2.3%; while in Example 1,

[0113] It can be seen from Figure 3 that at a certain fixed temperature, the emissivity of the sample surface varies with the wavelength, and the emissivity also varies with the temperature. Therefore, when using colorimetric temperature measurement, the assumption in the prior art that the ratio of the emissivities of two wavelengths is always a fixed value will cause errors in the results. However, in the present invention, the emissivity ratio is converged to a certain value through the iterative method to improve the accuracy of temperature and spectral emissivity.

[0114] By comparing Figure 4 and Figure 3 it can be seen that the spectral emissivity of Comparative Example 1 is mostly around 0.75, while the emissivity obtained after iterative correction using the present invention is mostly around 0.85. The effect of iterative correction is relatively significant.

[0115] Compare the sample temperature of 1601K calculated in Comparative Example 1 with the sample temperature of 1500.5K obtained after multiple iterations in Example 1. The deviation between the two is 6.7%. From the comparison results, it can be seen that during the temperature measurement process using a colorimetric thermometer in the high-temperature emissivity test, using the method of the present invention to iteratively correct the temperature and spectral emissivity can effectively improve the accuracy of temperature and emissivity measurement.

[0116] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for detecting the true temperature and emissivity of a sample, characterized in that, The method includes: (a) Calibrate the color contrast thermometer to obtain the transmittance ratio of the light with two wavelengths λ1 and λ2 of the color contrast thermometer in the optical path system of the emissivity test device. Among them, τ1 is the transmittance of the optical path system to the light with wavelength λ1, and τ2 is the transmittance of the optical path system to the light with wavelength λ2. (b) Place the sample to be measured in the emissivity test device, heat it and make the temperature reach a stable state. According to Planck's theorem, the relationship between the temperature measured by the colorimetric thermometer and the true temperature of the sample surface is as shown in Equation (4). Among them, T r is the true temperature of the sample surface; T is the temperature directly measured by the colorimetric thermometer; λ1, λ2 are the two wavelengths of the colorimetric thermometer; ε(λ1, T r ) and ε(λ2, T r ) are the emissivities corresponding to the two wavelengths of λ1 and λ2 at T r temperature respectively; c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; Rearrange Equation (4) to obtain Equation (5). Among them, T r is the true temperature of the sample surface; T is the temperature measured by the colorimetric thermometer; λ1 and λ2 are the two wavelengths of the colorimetric thermometer; ε(λ1, T r ) and ε(λ2, T r ) are the emissivities corresponding to the two wavelengths of λ1 and λ2 at T r degrees respectively; c2 is the second radiation constant, 1.4388×10 -2 m·K; (c) Set as an initial constant, and calculate (T r ) through Equation (5), and then obtain the spectral emissivity distribution curve ε(λ, (T r )); (d) Correct the result of step (c) according to Planck's theorem.

2. The method according to claim 1, wherein Step (d) includes: calculating using ε(λ1, T r ) and ε(λ2, T r ) in the spectral emissivity distribution curve obtained in step (c), and then substituting the obtained into Equation (5) for calculation. Repeat the iterative operation in this way until the obtained in the last iteration is close to the obtained in the previous iteration. Then, the (T r ) and ε(λ, (T r r )) obtained in the last iteration are the true temperature of the sample surface and the spectral emissivity curve at this temperature, respectively.

3. The method according to claim 2, wherein Steps (c) to (d) include: (c-1) Assume an initial Substitute into Equation (5) and calculate to obtain (T r )1; (c-2) Obtain the spectral emissivity distribution curve ε(λ, (T r )1) at a temperature of (T r )1; (d-1)According to the spectral emissivity distribution curve ε(λ,(T r )1)1, extract the emissivity values ε(λ1)1 and ε(λ2)1 corresponding to λ1 and λ2, and compare the two to obtain (d - 2) Substitute m1 into Equation (5) and repeat steps (c - 1), (c - 2), and (d - 1) for i times to obtain (T r ) i , ε(λ, (T r ) i ) i and m i ; when m i and m i-1 meet the similar requirements, the iterative operation ends, and (T r ) i , ε(λ, (T r ) i ) i are the true temperature of the sample surface and the spectral emissivity curve at this temperature, respectively.

4. The method according to claim 3, wherein In step (c-2), the spectral emissivity distribution curve ε(λ, (T r )1)1 at the obtained temperature of (T r )1 includes: calculating the distribution curve of the radiation energy of an ideal blackbody at the temperature of (T r )1 according to Planck's theorem, measuring the radiation energy distribution curve of the sample surface with a spectrometer, and dividing the radiation energy of the sample surface by the radiation energy of the ideal blackbody to obtain the spectral emissivity distribution curve ε(λ, (T r )1)1.

5. The method according to claim 4, wherein The spectrometer is a Fourier spectrometer.

6. The method according to claim 3, wherein In step (d-2), the proximity requirement is 7. The method according to claim 1, wherein In step (a), a blackbody furnace is used to calibrate the colorimetric thermometer.

8. The method according to claim 7, wherein The calibration of the colorimetric thermometer using a blackbody furnace includes: Put a blackbody furnace in the emissivity test device and set the temperature to T bf , the emissivity of the blackbody at all wavelengths is 1. Therefore, the ratio of the emissivities of the two wavelengths λ1 and λ2 in the colorimetric thermometer is 1, and the colorimetric thermometer directly measures the ratio of the radiation energies corresponding to λ1 and λ2 According to Planck's theorem, calculate the temperature T from Equation (1); wherein, c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; T is the temperature measured by the colorimetric thermometer; λ1 and λ2 are the two wavelengths of the colorimetric thermometer; For the temperature measurement optical path system, if the light transmittances of the two wavelengths λ1 and λ2 of the colorimetric thermometer are τ1 and τ2 respectively, then the relationship between the temperature T and the true temperature T of the blackbody furnace is as shown in Equation (2). bf is as follows where, c1 is the first radiation constant, 3.742×10 -16 W·m 2 ; c2 is the second radiation constant, 1.4388×10 -2 m·K; T is the temperature measured by the colorimetric thermometer; T bf is the true temperature of the blackbody furnace; λ1 and λ2 are the two wavelengths of the colorimetric thermometer; τ1 and τ2 are the light transmittances of the two wavelengths λ1 and λ2 of the colorimetric thermometer, respectively; Rearranging Equation (2) gives Equation (3). The temperature T directly measured by the colorimetric thermometer is compared with the true temperature T of the blackbody furnace bf Substituting into Equation (3), the transmittance ratio of the two wavelengths λ1 and λ2 of the colorimetric thermometer by the temperature measurement optical path system is obtained 9. The method according to claim 8, wherein The position of the blackbody furnace in the emissivity test device is the same as the position where the sample is placed.

10. The method according to claim 1, characterized in that, In step (b), the heating includes: heating the sample at a constant power by manually adjusting the power of the power supply.

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