LES and RANS of air and oxy-coal combustion in a pilot-scale facility: Predictions of radiative heat transfer

• LES and RANS predictions are made of a pilot-scale combustion test facility.
• Heat flux measurements from air and oxyfuel experiments are compared with CFD predictions.
• FSCK and WSGG models are examined in RANS and LES calculations.
• LES considerably improves the prediction of radiative heat flux.
• LES with FSCK shows the best overall agreement with the measurements.

This study evaluates the use of large eddy simulation (LES) and Reynolds-averaged Navier Stokes (RANS) models for the prediction of turbulent coal combustion under air and oxyfuel environments in a pilot-scale 250 kWth furnace. The furnace is part of the UKCCSRC Pilot-scale Advanced Capture Technology (PACT) facilities and was designed for detailed analysis of the combustion process. The prediction of thermal radiation is validated against experimental measurements under both air- and oxy-firing regimes. Two radiation models were evaluated during the RANS calculations, the widely used weighted sum of grey gases (WSGG) and the full-spectrum correlated k (FSCK) model, while the LES case was calculated using the FSCK radiation model. The results show that the choice in gas radiation model demonstrates only a small change in the temperature and heat flux predictions in the RANS calculations, while the LES solutions are able to achieve better agreement with measured values than the RANS predictions for both air-fired and oxyfuel coal combustion.