Application of the weighted-sum-of-gray-gases model in enclosures with gray surfaces
Roberta Juliana Collet da Fonseca1; Aline Ziemniczak1; Francis Henrique Ramos França1
1 Federal University of Rio Grande do Sul
doi:10.20906/CPS/COB-2015-0769
Resumo
Thermal radiation is the main heat transfer mode in combustion problems due to high temperatures. However, it has been a challenge to make predictions about these processes due to the complex spectral dependence of the absorption coefficient. Therefore, it is necessary to use spectral models to obtain accurate results but requiring low computational effort. In combustion systems, the weighted-sum-of-gray-gases (WSGG) is widely applied to perform the spectral integration of the radiative transfer equation (RTE). This method replaces the integration of the entire spectrum by a few gray gases in order to simulate the real radiative properties of participating species. Thus, the spectrum is divided into regions where the absorption coefficient can be considered constant and each band is represented by one gray gas. In this work, the WSGG model is applied to a one-dimensional system composed of a flat plate parallel medium, in which surfaces are gray, with a mixture of carbon dioxide and water vapor based on the HITEMP 2010 database. The application of gas model is invariably demonstrated for black surfaces, for which the intensities at the boundaries are known, so the present study makes an advance to show its application to gray surfaces. The agreement of the results is analyzed by comparisons between the benchmark solution obtained by integrating line-by-line (LBL) and the WSGG model.
Palavras-chave: Radiative transfer; WSGG model; LBL integration; gray surfaces