Experimental Study On Short Wave Infrared Spectral Emissivity Characteristics Of Typical High-temperature Targets

The recognition and temperature inversion of high temperature targets(such as forest fire,coal spontaneous combustion,straw burning,industrial blast furnace,residential fire,etc.)is one of the important research objects in the field of remote sensing information detection and inversion in recent years.It has very important theoretical and practical value in the application fields of remote sensing resource investigation,disaster early warning,environmental monitoring,etc.Emissivity,as an important thermophysical parameter which can reflect the radiation ability of objects,is the key parameter which restricts the accuracy of remote sensing temperature inversion.Although scholars at home and abroad have done a lot of research on the emissivity characteristics of objects up to now,the spectral emissivity characteristics of various objects in the short wave infrared band are still lack of information.What are the characteristics and differences of the spectral emissivity of different materials and the influence of temperature on the emissivity need to be further studied.In this study,the experimental observation method was used to simulate the actual high temperature target by using graphite plate,304 stainless steel plate and heat-resistant cement plate heated by constant temperature electric heating plate,based on the definition of emissivity and the theory of black body radiation,the short wave infrared(1300-2500nm)spectral emissivity of the above object heated at 573-873 K is obtained,and the influence of random error in the process of experiment is eliminated by repeated experiments.The variance analysis method is used to analyze all kinds of objects The difference of spectral emissivity of objects in different temperature groups is analyzed,and the relationship model of spectral emissivity with temperature is established quantitatively by regression analysis method;the spectral morphological characteristics and differences of emissivity of different experimental objects are analyzed;finally,the uncertainty of measurement results is analyzed.The main results of this study are as follows: when the reliability ? = 0.05,the variance analysis results of emissivity in different temperature groups are significantly different.Within the experimental temperature range,with the increase of temperature,the emissivity spectral curve of graphite plate decreased by 13.5%-23.7%,that of 304 stainless steel plate decreased by 5.4%-18.8%,and that of heat-resistant cement plate decreased by 20.9%-41.8%.The linear fitting function can well express the relationship between spectral emissivity and temperature.The coefficient of determination is above 0.8,and the slope of the linear function decreases with the increase of wavelength.The spectral emissivity of 304 stainless steel plate is slightly lower than that of graphite plate,and the spectral emissivity decreases with the increase of wavelength;the spectral emissivity of heat-resistant cement plate is the lowest and increases with the increase of wavelength.The uncertainty of spectral emissivity measurement results is less than 0.015.Compared with low temperature point and short wavelength range,the accuracy of spectral emissivity measurement results at high temperature point and long wavelength range is higher.The experimental results show that the spectral emissivity of the experimental object is affected by the temperature and decreases with the increase of temperature;the spectral emissivity characteristics of different kinds of objects also have obvious differences.