The heat transfer from turbulent diffusion flames between vertical walls has been computed for different wall and burner configurations. The buoyancy-modified k - epsilon model was used to study the turbulent characteristics of the how. The flamelet concept, coupled to a prescribed probability density function, was employed to model the nonpremixed combustion process. With the nucleation, surface growth, coagulation, and oxidation considered, sooting was modeled by serving the balance equations for mass fraction and number density. The radiation from the main radiating species-carbon dioxide, water vapor and soot-was calculated using the discrete transfer method. A recently developed fast, narrow-band model was adopted to provide the radiation properties of the radiating species. Computations were performed for different cases by varying the wail separation and burner output. The results were analyzed and compared with experimental measurements, with which they showed good agreement. The effects of wall separation and burner output on heat transfer were faithfully reproduced.