Modification of the weighted-sum-of-grey-gases model to account for both air- and oxy-fired conditions
Konferensbidrag (offentliggjort, men ej förlagsutgivet), 2009
Radiative heat transfer is a key parameter for the design of a combustion chamber. The directional nature of radiation necessitates the solution and spatial integration of an equation known as the radiative transfer equation (RTE). The problem is made even more complicated by the spectrally dependent properties of the combustion gases, mainly H2O and CO2. In comprehensive combustion models, for example CFD-models, it is common that the spectral variations of the gases are neglected and that the spectrum is treated by a single average, i. e. a grey approximation. Oxy-fired conditions are in addition characterized by much higher molar fractions of emitting gases and possible different ratios of H2O to CO2. As many approximate models have a limited parameter range their use is limited to air-fired conditions, if more general conditions are to be covered the user is restricted to more complex models. The aim of this work is to modify a model to provide a computationally efficient option to account for non-grey properties of combustion gases in both oxy-fired and air-fired conditions.