Euler-Euler CFD Study of Heat Transfer in Fluidized Beds with an Immersed Surface Using the Kinetic Theory of Granular Flows
Priscilla Corrêa Bisognin1; José Mozart Fusco2; Cíntia Soares1
1 Universidade Federal de Santa Catarina; 2 Universidade Estadual de Campinas
doi:10.20906/CPS/CILAMCE2015-0585
Resumo
The Eulerian approach is largely applied in CFD simulations due to the great results it provides and the reduced computational effort needed, compared to other approaches like the discrete Lagrangian approach. It considers both phases as interpenetrating continuum, being generally called two-fluid model. In cases where one of the phases is a granular material, the fluid-like properties of this phase are commonly described by the kinetic theory of granular flows (KTGF). Recently, authors have been using the Eulerian approach and the KTGF to study this phenomena, however the simulation of these equipments is very complex and more studies need to be made in order to elucidate the influence of all the simulation parameters in the heat transfer process. This work has the objective of studying different simulation parameters and models, in order to obtain a setup that is capable of describing the heat transfer phenomenon in fluidized beds. For this, CFD simulations were conducted in the software ANSYS Fluent 14.0, using an axisymmetric geometry based in an experimental setup described in the literature. Four drag models were tested (three empiric models and one based on lattice-Boltzmann simulation results). Moreover, six values of specularity coefficient were tested (0, 0.05, 0.1, 0.25, 0.5 and 1) and it was found that this parameter not only alters the hydrodynamic of the bed, as many authors have appointed, but also influences the heat transfer. Finally, the effect of turbulence was considered. The selected model chosen in this work was the "RNG κ-ε dispersed" model. The κ-ε model is largely applied in fluidized bed simulations and the RNG κ-ε model presents improvements regarding the standard κ-ε model, and also is applicable for a wide range of different flows. Gidaspow's drag model was not only able to describe correctly the hydrodynamics of the bed, but also provided the value of heat transfer coefficient that was closest to the experimental. The optimum value of sp
Palavras-chave: CFD; Euler-Euler; Heat Transfer; Fluidized Beds; Kinetic Theory of Granular Flows