阅读说明：本技术 一种水蒸气介质环境下辐射测温比色波长确定方法 (Method for determining radiation temperature measurement colorimetric wavelength in water vapor medium environment ) 是由 倪修华 张发斌 龙木军 黄云伟 江中块 陈登福 李玉娣 于 2018-06-28 设计创作，主要内容包括：本发明涉及一种水蒸气介质环境下辐射测温比色波长确定方法,包括：计算平均气体透过率、平均吸收系数,再通过辐射传输方程计算光谱辐射强度分布,最终得到辐射能量衰减比例等步骤。本发明提供的水蒸气介质环境下辐射测温比色波长确定方法,借助最新高温谱线光谱数据库HITEMP2012计算该水蒸气的辐射特性,建立考虑水蒸气介质吸收与发射的热辐射传输方程,求解并获得由水蒸气引起的辐射能在各个波长上的衰减比例；通过对比各个波长上的衰减比例来科学确定比色测温的最优波长。(The invention relates to a method for determining radiation temperature measurement colorimetric wavelength in a water vapor medium environment, which comprises the following steps: and calculating the average gas transmittance and the average absorption coefficient, and calculating the spectral radiation intensity distribution through a radiation transmission equation to finally obtain the radiation energy attenuation ratio. The invention provides a method for determining radiation temperature measurement colorimetric wavelength in a water vapor medium environment, which comprises the steps of calculating the radiation characteristic of water vapor by means of a latest high-temperature spectral line spectrum database HITEMP2012, establishing a heat radiation transmission equation considering the absorption and emission of a water vapor medium, and solving and obtaining the attenuation proportion of radiation energy caused by the water vapor on each wavelength; the optimal wavelength of colorimetric temperature measurement is scientifically determined by comparing the attenuation ratio of each wavelength.)

1. A method for determining a radiation temperature measurement colorimetric wavelength in a water vapor medium environment is characterized by comprising the following steps:

(1) based on the HITEMP2012 high-temperature spectral line spectral database, in the Malkmus statistical narrow-band model, the average gas transmittance of the bands of the isothermal and uniform paths

in the formula, X is the mole fraction of water vapor on a channel, L is the thickness of a water vapor medium layer, and p is the pressure of the water vapor;and

(2) determining the average absorption coefficient k of the spectral band_αΔλ：

(3) the radiative transfer equation is:

the corresponding boundary conditions are:

where the subscripts Δ λ and b represent a band and a black body, respectively, μ is the cosine of the angle of the radiation propagation direction from the normal to the plane of the object to be measured, and I_Δλ(x, mu) represents the intensity of the band radiation at a point in the medium in a certain propagation direction, I_Δλ(0, mu) and I_Δλ(L, μ) is the spectral band radiation intensity of the measured object and the surrounding environment in each propagation direction, respectively; t is₁，T₂Is the temperature, epsilon, of the object under test and the surrounding environment, respectively₁And ε₂Is the emissivity of the measured object and the surrounding environment, p₁And ρ₂Is the reflectivity of the object to be measured and the surrounding environment, n is the refractive index, and σ is the stefan-boltzmann constant; solving the equation to obtain the spectral radiation intensity distribution of the dielectric layer;

(4) by the formula:

(5) the radiation energy attenuation ratio K is the ratio of the attenuated energy to the real energy:

wherein E_Δλ(T) is the theoretical energy over the narrow bandwidth, calculated quantitatively from planck;

(6) repeating the steps (1) to (5) by using other narrow bands to obtain the K value of each narrow band; the two narrow bands with the smallest difference in K values are the most preferred wavelengths.

Technical Field

The invention relates to a method for determining radiation temperature measurement colorimetric wavelength in a water vapor medium environment, and belongs to the technical field of radiation temperature measurement.

Background

The monitoring of the surface temperature of the continuous casting blank has important significance for optimizing the control of the continuous casting process and improving the surface quality of the casting blank. Real-time online monitoring of the surface temperature of the casting blank can provide important information for realizing closed-loop control of secondary cooling water, casting blank solidification and prejudgment of casting blank quality. At present, the surface temperature of a casting blank in a continuous casting secondary cooling area is mainly measured by a radiation thermometry method. However, due to the use of a large amount of cooling water in the secondary cooling zone, accurate measurement of the surface temperature of the casting blank still faces a great challenge.

In the continuous casting secondary cooling area, due to the high-temperature environment, water mist formed under the action of high pressure is instantaneously evaporated to generate a large amount of water vapor, so that the accurate measurement of the surface temperature of the casting blank is greatly influenced. The strong dipole moment and the hydrogen atoms in the water vapor result in a strong and broad absorption band. Furthermore, the asymmetric structure in water vapor also leads to irregular absorption spectra. When a large amount of high-temperature water vapor exists in a radiation temperature measuring optical path, the strong absorption and emission of the water vapor can cause the enhancement or weakening of a receiving signal of a temperature measuring instrument, and an unpredictable error is generated in a measured value. In this case, it is difficult for the conventional monochromatic radiation thermometer to obtain accurate and reliable measurement values.

In order to avoid the influence of the water vapor medium on the radiation energy transmission, the common practice in industry is to adopt a method of blowing the light path with high-speed gas flow (nitrogen or argon) to reduce the influence of the water vapor medium. Although blowing or the like is used to some extent to eliminate water vapor, residual water vapor in the radiation channels still affects the accuracy of the temperature measurement. And if the air velocity is too high, the surface temperature of the detected casting blank is reduced, thereby bringing new problems. Another method commonly used in industry is to use a sight tube to minimize the effect of the water vapor medium on the temperature measurement path, assisted by high velocity gas flow purging, but this method still has the drawbacks of the previous method. A third method commonly used in industry is to take the maximum value of the temperature over a period of time as a measurement. The method is effective for avoiding intermittent media in the light path channel, such as iron scale discontinuously distributed on the surface of the casting blank, water mist dust particles in the channel or not, and the like. However, this method does not exclude the presence of water vapor in the channel.

In order to reduce the influence of the water vapor medium on the radiation temperature measurement precision, a colorimetric model is also adopted for measurement. This method uses the ratio of the radiant energies over the two bands to determine the target temperature. The water vapor medium in the light path absorbs the electromagnetic waves of two wave bands, and although the absorption rates are different, the influence on the ratio of the monochromatic radiation intensity is relatively small. However, for radiation temperature measurement in the environment of water vapor with different concentrations, no scientific wavelength determination method is available, and accurate and reliable temperature is difficult to obtain.

Disclosure of Invention

The invention aims to solve the technical problems that: the defects of the technology are overcome, and a scientific determination method of the colorimetric temperature measurement optimal wavelength considering the attenuation and enhancement effects of water vapor on the transmitted radiant energy is provided.

In order to solve the above technical problem, a first technical solution proposed by the present invention is: a method for determining a radiation temperature measurement colorimetric wavelength in a water vapor medium environment comprises the following steps:

(1) based on the HITEMP2012 high-temperature spectral line spectral database, in the Malkmus statistical narrow-band model, the average gas transmittance of the bands of the isothermal and uniform paths

Comprises the following steps:

in the formula, X is the mole fraction of water vapor on a channel, L is the thickness of a water vapor medium layer, and p is the pressure of the water vapor;

and

respectively, the average absorption coefficient, the average spectral line density and the average half width in the spectral band;

and

calculated from the database hitemm 2012;

can be obtained from the following equation:

in the formula p_SIs at standard atmospheric pressure, T_S296K, T is the water vapor temperature;

(3) determining the average absorption coefficient k of the spectral band_αΔλ：

Where Δ λ is the bandwidth of the spectral band, k_αλThe mean ray path length L of the water vapor medium layer is the spectral absorption coefficient_NBEqual to 1.9 times L;

(3) the radiative transfer equation is:

the corresponding boundary conditions are:

where the subscripts Δ λ and b represent a band and a black body, respectively, μ is the cosine of the angle of the radiation propagation direction from the normal to the plane of the object to be measured, and I_Δλ(x, mu) represents the intensity of the band radiation at a point in the medium in a certain propagation direction, I_Δλ(0, mu) and I_Δλ(L,. mu.) are eachThe spectral band radiation intensity of the measured object and the surrounding environment in all propagation directions; t is₁，T₂Is the temperature, epsilon, of the object under test and the surrounding environment, respectively₁And ε₂Is the emissivity of the measured object and the surrounding environment, p₁And ρ₂Is the reflectivity of the object to be measured and the surrounding environment, n is the refractive index, and σ is the stefan-boltzmann constant; solving the equation to obtain the spectral radiation intensity distribution of the dielectric layer;

(4) by the formula:calculating the received radiant energy;

(5) the radiation energy attenuation ratio K is the ratio of the attenuated energy to the real energy:

wherein E_Δλ(T) is the theoretical energy over the narrow bandwidth, calculated quantitatively from planck;

(6) repeating the steps (1) to (5) by using other narrow bands to obtain the K value of each narrow band; the two narrow bands with the smallest difference in K values are the most preferred wavelengths.

According to the method for determining the radiation temperature measurement colorimetric wavelength in the water vapor medium environment, the radiation characteristic of water vapor is calculated by means of the latest high-temperature spectral line spectral database HITEMP 2012; establishing a thermal radiation transmission equation considering the absorption and emission of the water vapor medium, and solving and obtaining the attenuation proportion of the radiation energy caused by the water vapor on each wavelength; the optimal wavelength of colorimetric temperature measurement is scientifically determined by comparing the attenuation ratio of each wavelength. Accurate and reliable temperature measurement can be realized. The invention quantitatively considers the influence of the water vapor on the radiation energy on the basis of accurately calculating the radiation characteristic of the water vapor, and can effectively avoid the influence of a water vapor medium on the radiation temperature measurement on the basis of the colorimetric temperature measurement wavelength scientifically selected according to the attenuation proportion of the radiation energy in the water vapor environment. Suitable for varying water vapor concentrations. Through theoretical calculation, the wavelength selection method provided by the invention can realize accurate and reliable temperature measurement under different water vapor concentrations. The theoretical basis is sufficient. The method is deduced and proposed according to Planck's law and a Wien approximate formula, the radiation characteristic of the water vapor is calculated by means of a high-temperature spectral line spectrum database HITEMP, and the theoretical basis is sufficient.

Detailed Description