This work presents a numerical study of radiation heat transfer and its interaction with gray and spectral radiation of combustion products and soot that are formed in a turbulent non-premixed combustion process. To this purpose, weighted sum of gray gases (WSGGM), Rayleigh, narrow-band model, and semi-empirical radiation properties models are considered. Two situations are studied -1-D radiation problem and non-premixed gaseous combustion process. The results demonstrate that the models exhibit discrepancies that are smaller than the available line-by-line or experimental data. A study of the factors that influence such a disagreement is presented, underscoring the role of the chemical kinetics of hydrocarbon species and soot oxidation.