JPH0462009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring emissivity. In general, the emissivity of a sample changes depending on the material, temperature, oxidation state, surface roughness, wavelength, etc. of the sample. This is determined by measuring each radiation and finding the ratio, but this requires knowing the temperature of the sample and blackbody in advance, and the blackbody must be installed to have the same temperature, making the measurement complicated. There is a drawback. For example, if the sample is in an isolated location and contact temperature measurement is not possible, it is particularly difficult to measure emissivity. You can't know by formula.

The purpose of the present invention is to solve these drawbacks, and while measuring the spectral thermal radiation of four or more color wavelengths by spectrally dispersing the thermal radiation from the sample, it also measures the spectral thermal radiation of four or more color wavelengths. Assuming an approximation formula, calculate the temperature from the approximate spectral thermal emissivity of the wavelengths of the three colors among the wavelengths in the linear approximation formula and the spectral thermal radiation of the measurement corresponding to the three colors, and calculate the temperature using the linear approximation. Determine the temperature from the approximate spectral thermal emissivity of the wavelength of three colors including the remaining colors among the four or more colors in the formula and the measured spectral thermal emissivity corresponding to the three colors including the remaining colors, The method is characterized in that the temperature at which the respective determined temperatures match is taken as the temperature of the sample, and the spectral thermal emissivity of the sample is determined from this temperature, the measured wavelength, and the spectral thermal radiation.

An embodiment of the present invention is shown in a vacuum container 1 as shown in the first diagram.
A case will be explained in which the emissivity of the sample 2 contained in the sample 2 is measured.

In the figure, reference numeral 4 denotes a spectroscope 5 that separates the thermal radiation of the sample 2 into multiple wavelengths through the vacuum window 3, a detector 6 that detects the amount of the spectroscopic thermal radiation, and its detected value. For example, a radiation thermometer equipped with a microprocessor 7 is shown, and the spectroscope 5 separates the thermal radiation into four or more colors of wavelengths, and each spectral thermal radiation is divided into spectral numbers. They are simultaneously measured by a detector 6 having a light receiving section, and each measured value is submitted to a microprocessor 7 for calculation to determine the emissivity of the sample 2. Generally, when measuring the emissivity of a sample using a radiation thermometer, it is necessary to also install a blackbody to measure the thermal radiation from this body.
In the present invention, the emissivity of the sample can be accurately determined without particularly providing a blackbody.

In the example, it is assumed that the temperature of the sample 2 is T, the thermal emissivity is ε, and the thermal radiation is L. Of these, the temperature T and thermal emissivity ε are unknown quantities, and the thermal radiation L is spectrally divided into wavelengths λ ₁ , λ ₂ ... λ _o of four or more colors, and the spectral thermal radiation L ₁ , L ₂ at each wavelength is ...L _o is radiation thermometer 4
It is measured by

On the other hand, the spectral thermal emissivity ε ₁ , ε ₂ ...ε _o at each wavelength λ ₁ , λ ₂ ...λ _o cannot be determined without knowing the thermal radiation to be compared, such as the thermal radiation of a black body. However, it is known that it changes along a certain curve, and as shown in the second diagram, the spectral thermal emissivity ε ₁ , ε ₂ ...
A linear approximation equation εc of the spectral thermal emissivity passing through each point or the vicinity of each point of ε _o can be assumed. This approximate expression ε _c can be expressed as a linear expression of the wavelength λ as follows.

ε _c = aλ + b ... [] If the measured spectral thermal radiation L _o is the spectral thermal radiation from the black body as L ^* _o , then L _o = ε _c・L ^* _o = (aλ _o + b)・L ^* _o …[] becomes. This L ^* _o is obtained from Blank's formula: L ^* _o = C ₁ / λ ⁵ / _o・1/exp (C ₂ / λ _o T) − 1... [
], where C ₁ is 1.19196×10 ^-p [W・
m ² ], C ₂ is a constant expressed as 0.014388 [m·K].

In addition, the formula [] is determined by actual measurement as L ₁ = (aλ ₁ + b)・L ^* ₁ L ₂ = (aλ ₂ + b)・L ^* ₂ L ₃ = (aλ ₃ + b)・L ^* ₃ L ₄ = (aλ ₄ + b )・L ^* ₄ [], and if we eliminate the coefficients a and b using the above formula [] regarding the wavelengths of the three colors λ ₁ , λ ₂ , λ ₃ , we get L ₁ /L ^* / ₁ (λ ₃ −λ ₂ )+L ₂ /L ^* / ₂ (λ ₁ −λ ₃ ) +L ₃ /L ^* / ₃ (λ ₂ −λ ₁ )=0…[]. In this case, the heat radiation L ^* _o from the black body is []
Since it is given by the formula, the [] formula is y=L ₁ λ ⁵ ₁ [exp(C ₂ /λ ₁ T)−1]・(λ ₃ −λ ₂ ) +L ₂ λ ⁵ ₂ [exp(C ₂ /λ ₂ T) −1]・(λ ₁ −λ ₃ ) +L ₃ λ ⁵ ₃ (exp(C ₂ /λ ₃ T)−1)・(λ ₂ −λ ₁ )
=0...[], and when this y is plotted against the temperature T by the microprocessor 7, two solutions are obtained as shown in the third figure.
You can find T _A and T _B. Therefore, since it is not possible to determine whether either T _A or T _B is the temperature of sample 2, the remaining colors of the measurement wavelengths, that is, three colors including λ ₄ , for example, λ ₂ , λ ₃ , λ Eliminate the coefficients a and b from the above [] formula regarding the wavelength of ₄ , and obtain y = L ₂ λ ⁵ ₂ [exp (C ₂ / λ ₂ T) - 1] · (λ ₄ - λ ₃ ), which is the same as []. +L ₃ λ ⁵ ₃ [exp(C ₂ /λ ₃ T)-1]・(λ ₂ −λ ₄ ) +L ₄ λ ⁵ ₄ (exp(C ₂ /λ ₄ T)−1]・(λ ₃ −λ ₂ )
=0... [] Plot the temperature T to obtain two solutions T _C and T _D as shown in the fourth diagram.

As a result, if T _A = T _C and T _B ≠ T _D , it can be determined that T _A is the temperature of sample 2.

Even if you plot the equation [][] at temperature T, there may be no solution and it may have a minimum value as shown in Figure 5, but in that case, if y at T _E is close to zero, then T _E
can be determined to be the approximate temperature of sample 2.

Further, as shown in FIG. 6, there may be cases where there is neither a solution nor a minimum value, but in this case, it is possible to measure and calculate the thermal radiation by changing the wavelength λ to obtain the temperature T or an approximate temperature. The wavelength λ may be four or more colors. For example, in the case of six colors, the thermal radiation of the sample 2 is λ ₁ ...
Spectral measurement can be performed at a wavelength of λ ₆ , and calculations can be made by dividing it into λ ₁ ... λ ₃ and λ ₄ ... λ ₆ .

When the temperature T of the sample 2 is determined in this way, from the actually measured spectral thermal radiation L _o and the wavelength λ _o , the approximate spectral thermal emissivity ε ₁ , ... ε _o at each wavelength is calculated using the formulas [ ] and [ ].
can be found.

As described above, according to the present invention, the thermal radiation of a sample is spectroscopically measured in four or more colors, and the temperature of the sample is determined by applying three colors each from the linear approximation formula of the spectral thermal emissivity and the measured spectral thermal radiation. Since the approximate spectral thermal emissivity is calculated from this temperature and the actually measured spectral thermal radiation and wavelength, there is no need to set up a comparison target such as a blackbody, and the emissivity can be easily measured without contact. There are effects such as being able to know the emissivity.

[Brief explanation of the drawing]

Fig. 1 is a diagram of one example of the measuring method of the present invention, Fig. 2 is a diagram of an example of the measuring method of the present invention;
The figure is a diagram showing the relationship between spectral thermal emissivity and a linear approximation formula, and FIGS. 3 to 6 are curve diagrams of y obtained by plotting with temperature T.

Claims (1)

[Claims] 1. While spectroscopically measuring the spectral thermal radiation of four or more color wavelengths by spectroscopy of the thermal radiation from the sample, a linear approximation formula for the spectral thermal emissivity at each wavelength is assumed, and the wavelength in the linear approximation formula is The temperature is determined from the approximate spectral thermal emissivity of the wavelengths of three of the colors and the measured spectral thermal radiation corresponding to the three colors, and the remaining wavelengths of the four or more colors in the linear approximation formula are calculated. 3 including colors
The temperature is determined from the approximate spectral thermal emissivity of the wavelength of the color and the measured spectral thermal radiation corresponding to the three colors including the remaining colors, and the temperature at which the respective determined temperatures match is taken as the temperature of the sample, and this temperature An emissivity measurement method characterized in that the spectral thermal emissivity of the sample is determined from the measured wavelength and the spectral thermal radiation.