An assessment of weighted-sum-of-grey-gases models for computational fluid dynamics modelling of hydrogen flames and thermal plasmas in kilns

• Gas radiation models are applied to hydrogen flames and thermal CO 2 plasmas. • Radiation effects on combustion systems, lacking particles, are presented. • In 1D calculations, the choice between gas radiation models is essential. • In 3D calculations, the implementation of a non-grey gas model is critical. • With particles included, a grey gas model is sufficient to describe radiation. This work aims to assess gas radiation models for CFD radiative transfer calculations in novel high-temperature processes that applies hydrogen flames and thermal plasmas as heat sources and relates it to a conventional coal flame. The analysis includes a comparison between the latest weighted-sum-of-grey-gases model (WSGGM) to standard WSGGM used in commercial CFD codes as well as grey and non-grey implementations. The new high-temperature processes holds higher temperatures, steeper temperature gradients and higher concentrations of radiating gases ( H 2 O and CO 2 ) but lack radiating particles. At the new conditions an updated WSGGM and a non-grey implementation is required to describe the radiative source term accurately. Especially for local conditions in hydrogen flames or thermal plasmas, the choice of WSGGM is crucial as temperature and gas concentrations may be outside conventional models’ validity range. However, for overall heat transfer calculations within the kiln, assuming a non-grey gas becomes more critical than the choice of WSGGM.