Spectral radiation modeling of gas and soot in glass melting furnaces: Evaluation of RC-SLW vs. WSGG model

Accurate modeling of thermal radiation is crucial for optimizing heat transfer in glass melting furnaces, as it significantly influences flame behavior within the combustion space. Despite its importance, existing literature lacks comparative studies that solve radiation with spectral accuracy and examine different spectral radiation models in combustion atmospheres. This study addresses this gap by comparing the Rank-Correlated Spectral Line-based Weighted Sum of Gray Gases (RC-SLW) model with gray and non-gray WSGG models. The objective is to investigate the impact of different radiation models on combustion behavior and radiative heat transfer in an industrial-scale glass furnace. The combustion process is modeled using a partially premixed steady diffusion flamelet model, the Moss-Brookes soot mechanism for soot formation and oxidation, and the k-omega SST turbulence model. Spectral radiation effects are assessed by implementing the RC-SLW model in ANSYS Fluent through a user-defined function. The RC-SLW model is validated with a 1-D simulation and compared against the line-byline model solution. Ten cases are examined. The results show that the gray WSGG model overestimates incident radiation by 10% compared to the RC-SLW model, with this discrepancy increasing to 25% when soot radiation is considered. The gray WSGG model also underestimates crown temperatures by up to 11%, while RC-SLW predictions closely align with experimental data, showing a maximum deviation of 6%. Non-gray WSGG models predict similar incident radiation values as the soot-inclusive RC-SLW model (approximately 40% of total energy), but crown temperatures differ significantly. Soot-only WSGG models show temperature discrepancies of up to 20%. These findings underline the importance of accurate spectral radiation modeling to improve furnace simulation accuracy and optimize heat transfer efficiency.