CFD modelling of bed shrinkage and channelling in fixed-bed combustion

An overview of processes and considerations in the modelling of fixed-bed biomass combustion

“…There is still need to study volume shrinkage during char burning and oxidisation and define a shrinkage threshold point. With the exception of few works [74], channelling phenomena, particle collapse and local porosity are essential factors in real combustions which are yet to be considered in the investigations of Table 19 The most common radiation models arrested in the literature.…”

“…This suggests that the channelling effect was not taken into account. Hermensson and Thunman [74] formulated a shrinkage model of a char particle during thermal conversion for multiple particle sizes. This model is based on a combination of continuous bed shrinkage and local porosity growth as results of thermal conversion.…”

Simulation of the Effect of Water Temperature on Domestic Biomass Boiler Performance

“…The kinetics of the global combustion mechanism of Westbrook and Dryer used by Yin et al [21] was used to compute the homogeneous reactions. Reasonably good predictions for the major species were obtained using similar oxidation models [28]. Equations (21) and (22) model the combustion of ammonia, which represents the species derived from the nitrogen present in the fuel.…”

A study on the dynamic combustion behavior of a biomass fuel bed

“…Schmidt number T temperature (K) T g temperature of the gas phase (K) t k time instance k (s) T s temperature of the solid phase (K) The issue of air channeling through a fuel layer in a fixed bed has also received attention (Yang et al [13], Hermansson and Thunman [14], Duffy and Eaton [15]). The authors noticed that channeling redirects the air flow resulting in uneven bed combustion.…”