| Summary: | Accounting an effect of cluster formation on hydrodynamics
of FCC riser is critical, and the energy minimization
multiscale (EMMS) model provides a framework to capture
clusters by using a cluster diameter correlation. In this study,
different cluster diameter correlations (CDC) were used with
the EMMS model to calculate structure-based drag
coefficients, and these drag coefficients were then used to
carry out CFD simulations of 2D riser with both low and high
flux flows of FCC particles. Initial simulations using the
EMMS and Gidaspow drag model showed that the EMMS
model could capture an S-shape axial profile with a dense
bottom and dilute top with showing qualitative agreements
with experimental data. The EMMS drag largely depends on a
cluster diameter correlation. Therefore, simulations were
performed using the EMMS drag coefficients calculated from
different CDCs i.e. (i) Chavan, (1984), (ii) Harris et al., (2002)
and (iii) Subbarao, (2010). It was found that the cluster
diameter correlations had considerable effect on the calculated
drag and hydrodynamic predictions. While no universal
agreement was observed between the hydrodynamic
prediction from different CDCs and experimental data. Thus,
it was concluded that a combination of CDCs in different
ranges of voidages can be useful to achieve qualitative
agreements between the hydrodynamics predictions and experimental data, and this study can be used to identify possible this combination of the CDCs for a given flow
system.
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