CN114441045B - Method for accurately measuring radiation temperature - Google Patents

Abstract

The invention belongs to the field of infrared radiation temperature testing and relates to a method for accurately measuring radiation temperature. The present invention is based on the radiation energy of other objects received by the same background and the same location object and the atmospheric radiation energy of this location is the same, considering that the background environment can not be changed, the radiation temperature of the object to be measured can be calculated using known conditions; in order to reduce the impact of external heat sources on the object to be measured Measure the influence of the radiation temperature of the object, and further use the heat insulating material to wrap the test object. By measuring the radiation temperature of the reference object, the radiation energy received by any object at a certain position and the atmospheric radiation energy are calculated, and the calculation result is used as a reference to calculate the radiation temperature of the object to be measured, with high accuracy. The device used in the invention is simple, easy to operate, and low in price, can promote the development of infrared detection technology and infrared camouflage technology, and also has guiding significance for the design of infrared cameras.

Description

A Method of Accurately Measuring Radiation Temperature

technical field

The invention belongs to the field of infrared radiation temperature testing, and relates to a method for accurately measuring radiation temperature, which uses a thermal insulation material as an auxiliary device and combines mathematical methods to solve the radiation temperature.

Background technique

Infrared radiation temperature measurement technology has important applications in infrared radiation cooling, infrared absorbing materials, and infrared thermal imaging technology. In the process of scientific research, researchers always use infrared cameras to detect the radiation temperature of objects, but few people quantitatively calculate the radiation temperature of objects. The main reason is that when using infrared cameras for detection, the energy received by the camera will be affected by the external environment. interference, that is to say, the radiation energy detected by the camera is always inaccurate, so the radiation temperature cannot be simply calculated by the Stephen-Boltzmann law.

In order to be able to accurately calculate the radiation temperature, the current high-precision infrared camera realizes the radiation temperature measurement by setting important parameters such as emissivity, atmospheric transmittance and atmospheric temperature; however, some parameters are difficult to obtain in actual tests, and no matter how they are set, the outside Reflection is always an influencing factor that cannot be eliminated. In addition, high-precision cameras are expensive and expensive to maintain. How to use simple equipment to accurately obtain the radiation temperature of the sample to be tested is facing a dilemma.

Contents of the invention

In view of the above existing problems or deficiencies, in order to solve the problems of high cost and relatively insufficient precision faced by the existing high-precision radiation temperature measurement, the present invention proposes a method for accurately measuring radiation temperature. The present invention selects heat-insulating material (such as the outer side is aluminum foil and the inner side is thermal insulation rubber and plastic cotton) to wrap the object to be measured, so as to reduce the influence of the external heat source on the radiation temperature of the object to be measured; then select a total emission black body and a total reflection gold foil as With reference to the object, measure the radiation temperature of the black body and the gold foil in the environment where the sample to be tested is located, and calculate the atmospheric radiation energy at this position and the energy received by the test object from the surrounding environment, and measure the temperature at this position. When measuring the object, the radiation temperature of the object to be measured is calculated and solved by combining the measurement results of the above-mentioned reference object.

A method for accurately measuring radiation temperature, the specific operation process is:

Step 1. Place a thermal insulation material in the environment where the object to be measured is located. The object to be measured is wrapped, leaving only one shooting window. A black body (emissivity is approximately equal to 1) is placed inside the package cavity of the thermal insulation material, and the infrared camera is placed on the shooting window ( For example, directly above the sample), measure the radiation temperature T ₁ of the black body on the sample at this time; replace the black body with gold foil, and measure the radiation temperature T ₂ of the gold foil (emissivity is approximately equal to 0) in the same way.

Step 2. Place the object to be tested under the same test position as the blackbody in step 1, and keep the position of the camera unchanged in step 1, and measure its radiation temperature.

Step 3, using the infrared camera formula and Stephen-Boltzmann's law:

E(T _rad )＝ε _eff ，τE(T _obj )+(1-a _eff )τE(T _sur )-(1-τ)E(T _atm ) (1)

E(T)＝gσT ⁴ (2)

In formula 1, E(T _rad ) is the radiation energy received by the infrared camera, ε _eff is the equivalent emissivity of the object to be measured at 8-14 μm, and τ is the atmospheric transmittance, which is generally 0.95; E(T _obj ) is the The radiation energy of the object itself is measured, a _eff is the equivalent absorption rate of the object to be measured in the whole band is approximately equal to ε _eff , E(T _sur ) is the energy reflected from the surrounding environment, E(T _atm ) is the energy in the test environment The radiant energy of the atmosphere.

Equation 2 is the Stephen-Boltzmann law, E(T) is the radiation energy of the object, ε is the emissivity, σ is the Stephen's constant, and its value is 5.670373×10 ^-8 W·m ^-2 ·K ^-4 , T is the object temperature.

Equation 3 is derived using Equation 1 and Equation 2.

The emissivity of a black body is 1, and the reflectance is 0, so the measured radiation temperature of a black body is expressed as:

At this time, the blackbody temperature is equal to the atmospheric temperature T _obj =T _atm , so we get:

T _atm = T ₁ (5)

The reflectivity of gold foil can be regarded as 1, and the radiation and absorptivity can be regarded as 0, so the radiation temperature of gold foil measured by infrared camera is expressed as:

so:

Step 4. Based on the results T _atm , T _sur calculated in the above step 3 and the measured equivalent emissivity E _eff of the sample, and use formula 1 to obtain the radiation temperature T _rad of the object to be measured.

Further, the outer side of the thermal insulation material is metal, and the inner side is thermal insulation material, so as to minimize the influence of external heat sources on the radiation temperature of the object to be measured.

Further, the outer side of the thermal insulation material is aluminum foil, and the inner side is thermal insulation rubber and plastic wool.

Further, the

The present invention is based on the fact that the radiation energy of other objects received by an object at the same background and the same position is the same as the atmospheric radiation energy at this position. Considering that the background environment is not changed, the radiation temperature of the object to be measured can always be calculated using known conditions. In order to reduce the influence of the external heat source on the radiation temperature of the object to be tested, the test object is further wrapped with a heat insulating material. Make full use of the radiation energy received by the infrared camera, which can be classified into three categories: self radiation, external reflection and atmospheric radiation. By measuring the radiation temperature of the reference object (black body and gold foil), it can be calculated that any object at a certain position can receive The radiant energy and atmospheric radiant energy, the calculation results are used as a reference to calculate the radiation temperature of the object to be measured, and the accuracy is high.

In summary, the present invention makes full use of the principle of an infrared camera, uses two reference objects, and combines the measured values of the object to be measured to finally accurately calculate the radiation energy of the object to be measured, which can promote the development of infrared detection technology and infrared camouflage technology. development, and also has guiding significance for the design of infrared cameras. And the device used in the present invention is simple, easy to operate, and cheap.

Description of drawings

Figure 1 shows the change process of the equivalent emissivity of the object to be measured with temperature;

Fig. 2 is a front view picture of a cylindrical heat insulating material;

Fig. 3 is a picture of a top view of a cylindrical heat insulating material;

Fig. 4 is the radiation temperature of the aluminum foil and blackbody that embodiment measures on laboratory floor;

Figure 5 is a comparison of the radiation temperature obtained by calculation and the radiation temperature obtained by testing.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

In this embodiment, the phase-change material _VO2 is used as the object to be measured. First, the Fourier spectrometer and Lincoln hot stage are used to measure its infrared spectrum at different temperatures, and then its equivalent emissivity is calculated to obtain its different temperature The equivalent emissivity under is shown in Fig. 1. The outer side of the thermal insulation material used is aluminum foil, and the inner side is thermal insulation rubber and plastic cotton.

A method for accurately measuring radiation temperature, the specific steps are as follows:

Step 1. Place a cylindrical heat insulating material on the laboratory floor. Its front view and top view are shown in Figure 2 and Figure 3 respectively. A black body is placed inside the cylinder, and an infrared camera is placed above the sample to measure the temperature of the sample at this time. The radiation temperature of the blackbody is 20.1°C, which is 293.25K. In the same way, the radiation temperature of gold foil is calculated to be 30°C, which is 303.15K. The test results of the infrared camera are shown in Figure 4.

Step 2. Place the sample to be tested at the same test position as in step 1, keep the position of the camera unchanged in step 1, and measure the radiation temperature of the sample to be tested.

Step 3, using the infrared camera formula and Stephen-Boltzmann's law:

E(T _rad )＝ε _eff *τE(T _obj )+(1-a _eff )τE(T _sur )-(1-τ)E(T _atm ) (1)

E(T)＝εσT ⁴ (2)

Where E(T _rad ) is the radiant energy received by the infrared camera, E _eff is the equivalent emissivity of the sample at 8-14 μm, τ atmospheric transmittance, generally 0.95; E(T _obj ) is the radiant energy of the sample itself, a _eff is the equivalent absorption rate of the sample in the whole band approximately equal to ε _eff , E(T _sur ) is the energy reflected from the surrounding environment, and E(T _atm ) is the radiant energy of the atmosphere in the test environment.

Equation 2 is the Stephen-Boltzmann law, E(T) is the radiation energy of the object, ε is the emissivity, σ is a constant, and its value is 5.670 373×10 ^-8 W·m ^-2 ·K ^-4 , T is the object temperature.

Equation 3 can be derived using Equation 1 and Equation 2.

The emissivity of a black body is 1, and the reflectivity is 0. The measured radiation temperature is expressed as:

At this time, the blackbody temperature is equal to the atmospheric temperature T _obj =T _atm , so we get:

T _atm =T ₁ =293.25K (5)

The reflectivity of gold foil can be regarded as 1, and the radiation and absorptivity can be regarded as 0, so the radiation temperature measured by the infrared camera

so:

Step 4. According to the results T _atm and T _sur calculated in the above step 3 and the measured equivalent emissivity ε _eff of the sample, the radiation temperature T _rad of the sample is calculated by using formula 1.

The radiation temperature calculated under different emissivity of the sample to be tested is compared with the radiation temperature obtained by actual measurement, and made into Figure 5.

It can be seen from the above examples that even though the temperature of the sample itself is constantly changing, the radiation temperature obtained by using the method of the present invention is basically consistent with the radiation temperature actually measured. The method has the advantages of high precision, simple and easy-to-manufacture device, convenient operation, low requirement on the precision of the infrared camera, and the calculation method is suitable for various external environments. The method of the invention can be used to calculate the radiation temperature of any object (the embodiment is that the phase change material is still valid). Under the condition that the error is allowed, the radiation temperature of the object calculated in the embodiment is basically the same as the radiation temperature actually measured by the infrared camera, which fully demonstrates that the radiation temperature obtained by the method of the present invention is accurate.

Claims (4)

1. A method for accurately measuring radiation temperature, characterized in that, the specific steps are as follows: Step 1. Place the heat-insulating material in the environment where the object to be measured is wrapped, leaving only one shooting window, and place a black body inside the package cavity of the heat-insulating material, place the infrared camera on the shooting window, and measure the temperature on the sample at this time. The radiation temperature T ₁ of the black body; replace the black body with gold foil, and measure the radiation temperature T ₂ of the gold foil in the same way; Step 2. Place the object to be tested under the same test position as the black body in step 1, and keep the position of the camera unchanged in step 1, and measure its radiation temperature; Step 3. Use the infrared camera formula and Stephen Boltzmann's law: E(T _rad )＝ε _eff *τE(T _obj )+(1-a _eff )τE(T _sur )-(1-τ)E(T _atm ) (1) E(T)＝εσT ⁴ (2)

E(T _rad ) is the radiation energy received by the infrared camera, ε _eff is the equivalent emissivity of the object to be measured at 8-14 μm, and τ is the atmospheric transmittance; E(T _obj ) is the radiation energy of the object to be measured itself, a _eff is the equivalent absorption rate of the object to be measured in the whole band is approximately equal to ε _eff , E(T _sur ) is the energy reflected from the surrounding environment, and E(T _atm ) is the radiant energy of the atmosphere in the test environment; Formula (2) is Stephen Boltzmann's law, E(T) is the radiation energy of the object, ε is the emissivity, σ is Stephen's constant, and its value is 5.670373×10 ^-8 W·m ^-2 ·K ^-4 , T is the object temperature; Using formula 1 and formula 2 to derive formula 3; The emissivity of a black body is 1, and the reflectance is 0, so the measured radiation temperature of a black body is expressed as:

At this time, the blackbody temperature is equal to the atmospheric temperature T _obj =T _atm , so we get: T _atm = T ₁ (5) The reflectance of gold foil is regarded as 1, and the radiation and absorptivity are both regarded as 0, then the radiation temperature of gold foil measured by the infrared camera is expressed as:

so:

Step 4. Based on the results T _atm , T _sur calculated in the above step 3 and the measured equivalent emissivity E _eff of the sample, and use formula 1 to obtain the radiation temperature T _rad of the object to be measured. 2. The method for accurately measuring radiation temperature according to claim 1, characterized in that: the outer side of the thermal insulation material is metal, and the inner side is thermal insulation material. 3. The method for accurately measuring radiation temperature according to claim 2, characterized in that: the outer side of the heat insulating material is aluminum foil, and the inner side is insulating rubber and plastic wool. 4. The method for accurately measuring radiation temperature according to claim 1, characterized in that: the object to be measured is a phase change material.

Images