Evaluation of gas radiation models in CFD modeling of oxy-combustion

• CFD modeling of a typical industrial water tube boiler is conducted.
• Different combustion processes were considered including air and oxy-fuel combustion.
• SGG, EWBM, Leckner, Perry and WSGG radiation models were considered in the study.
• EWBM is the most accurate model and it’s considered to be the benchmark model.
• Characteristics of oxy-fuel combustion are compared to those of air–fuel combustion.

Proper determination of the radiation energy is very important for proper predictions of the combustion characteristics inside combustion devices using CFD modeling. For this purpose, different gas radiation models were developed and applied in the present work. These radiation models vary in their accuracy and complexity according to the application. In this work, a CFD model for a typical industrial water tube boiler was developed, considering three different combustion environments. The combustion environments are air–fuel combustion (21% O2 and 79% N2), oxy-fuel combustion (21% O2 and 79% CO2) and oxy-fuel combustion (27% O2 and 73% CO2). Simple grey gas (SGG), exponential wide band model (EWBM), Leckner, Perry and weighted sum of grey gases (WSGG) radiation models were examined and their influences on the combustion characteristics were evaluated. Among those radiation models, the EWBM was found to provide close results to the experimental data for the present boiler combustion application. The oxy-fuel combustion characteristics were analyzed and compared with those of air–fuel combustion.