RU1770780C - Method of polychromatic determining of actual temperature - Google Patents

Abstract

SUMMARY OF THE INVENTION: the radiation of a test object is reflected by means of a surface having a non-selective or qualitatively the same as in the radiating surface, increasing or decreasing nature of the dependence of the reflection coefficient on the wavelength. 1 s.p. f-ly, 1 ill.

Description

The invention relates to the field of radiation pyrometry and can be used in determining the temperature of solids or liquids.

A known method for the polychromatic determination of the true temperature, in which a correction signal is extracted from the natural radiation, which corrects the variation in emissivity during the measurement process.

There is also a method for the polychromatic determination of the true temperature of objects having, in the studied wavelength range, the increasing, decreasing or non-selective nature of the spectral dependence of reflectivity or emissivity, including measuring the ratios of components of the radiation spectrum of an object, including those raised to a power. In this method, correction is achieved by raising one or several components to a power, with indicators minimizing the effect of emissivity. Moreover, with a large difference between the emissivity values of various spectral components, the methodological error is completely impossible to completely eliminate, and sometimes impossible.

The aim of the invention is to increase the accuracy of polychromatic determination of the true temperature of objects by converging the emissivity coefficients in the studied wavelength range.

Obviously, the closer, for example, in the bichromatic pyrometer, the ratios of the values of the emissivity coefficients ei and closer Јi / Ј2 to unity and, consequently, the methodological error is less.

For example, when measuring the temperature of aluminum and its alloys in the processes of pressing and rolling, the methodological error cannot be obtained less than + 1-1.5%.

with

with

xj H O VI s O

The proposed method allows to bring the value of this error to ± 0.5% and even to ± 0.2 + 0.25%.

The essence of the invention lies in the fact that in the method of polychromatic determination of the true temperature of objects having in the studied wavelength range the increasing, decreasing or non-selective nature of the spectral dependence of reflectivity or emissivity, including measuring the ratios of the components of the radiation spectrum, including raised to the degree, radiation reflect the surface having non-selective or qualitatively the same as that of the object, increasing or decreasing nature of the dependence of the coefficient reflection wavelength

The method is as follows

The radiation is reflected by a surface having a non-selective or qualitatively the same as that of the object, increasing or decreasing nature of the dependence of the reflection coefficient on the wavelength.

The ratios of the components of the emission spectrum are measured, including those raised to the power.

The drawing shows an optical diagram of a device for implementing the method.

The circuit includes a radiating surface 1 of the object under study, a reflecting surface 2, for example, a flat mirror having a reflective coating with non-selective or qualitatively the same as the object increasing or decreasing nature of the dependence of the reflection coefficient on wavelength, window 3 in the reflecting surface 1, through which the pyrometer and the polychromatic pyrometer 4 are focused.

The dashed line shows the direct radiation from the radiating surface 1. Solid lines show the radiation from the surface 1, reflected by the reflector 2, also falling through the window 3 into the lens of the pyrometer 4.

According to the quantitatively proposed method,

Let us denote the total radiation fluxes with wavelengths AiAaAn incident on the pyrometer lens or fiber

via: Fi, F2Fn

then

F e + K / f- g / e, -) 2 ... F M «V -Ј2 M2 + MzVejV. ,,

{„--Јpep + kn (1-Јп) (1-Јп% п

where EI, Ј2Јn are the radiative abilities of a surface with wavelengths AI, Дг, ..., An; ;

bi, D2 ..., bn are spectral fluxes with wavelengths AI, hiAn; in the black body;

Ki, K2, ..., Kn coefficients determined by the spectral dependence of the reflection coefficient for the wavelengths Ah, A2AL; and geometry, including distance, angles of the mirror, its size and diameter of the window.

Thus, the ratio between the coefficients Ki, K2, ... Kp can be influenced by the choice of material of the reflecting layer of the mirror, the design, the optics of the reflector 2,

EXAMPLE 1. Consider the implementation of the proposed method on the simplest example of a bichromatic pyrometer, which initially works according to the spectral ratio pyrometer algorithm.

Let the wavelengths of such a pyrometer AI be 1.6 microns and A2 2.5 microns, and the radiation surface is aluminum. In this case, ei 0.12 and Ј2 0.08. Those. emissivity decreases with increasing wavelength.

For the sake of clarity, we assume that the spectral reflectivity of the reflector -2 is such that KI 0. This can be achieved by covering the mirror-2 with a reflective layer, for example, a light filter that transmits radiation from 2 and completely absorbs radiation on AI, i.e. Kt 0. K2 - we set 0.25 and we assume that the geometry of the system is such that it is enough to consider only one reflection.

We also assume that the true surface temperature is 800 K. Then, without a reflecting mirror, the methodological correction will be

Cr fff -f-Ј In%; LT 1--

those. L74388

-L. I'm Mr. I

- b, h microns

With reflective mirror

517707806

-1 L - Ј t methodological error in this method

lt with f 4-Ј K (f + Ј) will be defined by the expression:

.. 0,2dT-. L. Ep ° ° 8 „a J

  44388408 008-0.250-0.08) Ј4 1nЈ 1P0, bn UG

1DT 1 x 3.7 microns

L Now, let’s put it. which is due to the occurrence of the “mirror in | 0. and roughness, the emissivity of DT on the aluminum surface increased, and with an increase in roughness:

became: Ј, 0.35 I / Ј2 0.25 /

Ј1 0.35; 0.25 ,, 55S -

LT 6125 23 M ИЈ Н; Then the error in the usual method

spectral ratio, without rapprochement. t, d LT in

values of emissivity boo - on, - / / o.

children: When using the proposed method of rapprochement

At-1 4.44-106, 0.35 lmЈ, 0.12; (-Ј) to.

 14388 (G25 Reiipron; 222 2,

0, 08 (1-0, OB) 0.25 0.098}

,4%. 25

bp in 0.12 op-amp

When applying the proposed method of approximation: when smoothing the surface

thirty

AT 1 4 l4388 ° 6. ffOl12v

& c2 -3 7 1 w omsh sch

LT 5reu / ron; DT K.

P 0.25 + 0.25 ° (f- 0.25) 0.25 50 35

With rough surface

T 32 K; those. measurement error., 6

with a variation in emissivity 40DT 1 in

C2 L T 49 - 49

 1.25% .0351.09

| P 0.25 + 0.25 (1-0.25) -0.25 - So. in the traditional method of bichromatic pyrometry of the spectral ratio, the proposed method reduces the back-j- d. DT 9 - 4 Q s o / due to the approximation of the values of EI and its methodological T 800 error by 3 times.

Claims (1)

12.5 -9 3.5% without a mirror; 50 So, in the bichromatic method with pro5-4 1% with a mirror, the simplest automatic correction, EXAMPLE p2. Let us now consider the applied approach method, which allows the approach method to be bichromatic — to reduce the methodological error from the pyrometer with automatic variation of the emissivity for correction. Here, 55 250-300%, i.e. three times, there is an erection of a voltage proportional to the first spectral brightness in the Formula of the invention, degree n, where n In Ј 2 min / ln ei min, i.e. A method of polychromatic determination of the true temperature of objects having, in the studied wavelength range, the increasing, decreasing, or non-selective nature of the spectral dependence of reflectivity or emissivity, including measuring the ratios of the components of the radiation spectrum, including those raised to an extent that, in order to improve accuracy due to the convergence of the emissivity coefficients in the studied wavelength range, the radiation is reflected by a surface having selective or qualitatively the same as the object, the increasing or decreasing nature of the dependence of the reflection coefficient on the wavelength.