Evaluation of the discretization in the spectral resolution for the solution of the line-by-line method in problems with participating gases

Despite the complexity to solve problems involving radiation heat transfer in participating media, especially due to the strong spectral dependence of the absorption coefficient, thermal radiation cannot be neglected in several applications, such as in combustion processes. This study proposes modeling of the spectral absorption coefficient by means of line-by-line integration method (LBL), which can take into account in full detail the complex spectral dependence of the absorption coefficient. The HITEMP 2010 database is used to generate the absorption cross-sections. An evaluation as to the spectral resolution for the LBL integration is performed; the results show that, even for a considerably low spectral refinement, the LBL can still provide accurate results. The lower spectral resolutions are obtained through a methodology to reduce the LBL spectral discretization based on a reference spectrum, which contributes significantly to the satisfactory accuracy reported in this study. The analysis is applied to a set of one-dimensional, non-isothermal medium slabs. In this way, the LBL integration gains space to solve more complex engineering problems with viable computational time and may even be a viable alternative to the use of simpler spectral models such as SLW, WSGG, among others.