Bandwidth is an important parameter for gas radiative heat transfer calculation, and a parameter for the calculation of the cumulative distribution function in the correlated-k method. Analysis and calculation show that the constant bandwidth is unreasonable in the calculation of the cumulative distribution function. So bandwidth calculated from the modified wide band model is used in the cumulative distribution function calculation. Comparison with the narrow band correlated-k method shows that the present method is more precise than the traditional one.

Four basic types of integration of radiative exchange area are generalized using general symmetry and applied to ten kinds of computation.The kinds of partial blocks of the matrix of radiative direct exchange area are analyzed,and the whole matrix is classified into four types of partial areas.Utilizing general symmetry,the quantitative expressions for the computation reduction of the direct exchange area of both three dimensional and two dimensional systems are presented.