Image temperature calculation for gas and particle system by the mid-infrared spectrum using DRESOR and SNBCK model

Abstract

The balance between spatial and spectral resolutions plays a key role in image temperature measurement using Imaging Fourier Transform Infrared Spectroscopy (IFTS). In this study, the performance of different combinations of spatial and spectral resolutions was investigated in a two-dimensional (2D) rectangular enclosure filled with gas and particle. The distributions of ratios of energy scattered or reflected (DRESOR) method combined with the statistical narrow band correlated-k (SNBCK) model was developed to obtain the radiative intensity image. Then the image temperature was calculated by the spectral thermometry. The accuracy of the DRESOR-SNBCK method was examined by comparison with the finite volume method (FVM)-line by line (LBL) method. The results showed that the average relative deviation of the image temperatures calculated by the spatial resolutions of 1 × 57 pixel and 1 × 140 pixel was <0.4%, indicating the accuracy of image temperatures was not improved by the increment of spatial resolution. However, the average relative error increased from 4.3% to 7.0% with the number of spectral bands increasing from 18 to 36. In addition, the large relative error of DRESOR-SNBCK method occurred in the low image temperature region due to the scattering effects. The average relative deviation of the homogeneous and inhomogeneous cases was <0.5%, indicating that the image temperatures were not affected by the gas homogeneity.