Numerical simulations of flow structure and heat transfer in a central jet bubbling fluidized bed

An attempt has been made to model the flow structure and to predict heat transfer coefficients in a gas–solid bubbling fluidized bed operated with a central jet using a two fluid model with closures from the kinetic theory of granular flow. Quantities such as the fluid-to-particle heat transfer coefficient are not easily obtained practically from experiments with a high degree of accuracy thereby making computational methods attractive. The CFD model has been verified using experimental bubble properties obtained from the literature. Axial and lateral normal Reynolds stresses, energy spectra and granular temperatures have been computed. The simulations show that the maximum local instantaneous fluid-to-particle heat transfer coefficient occurs in the wake of the bubble. Heat transfer coefficients at the center of the bed exhibit high oscillations compared to the near wall region. However time averaged values in the near wall region are larger compared to the bed center. The average heat transfer coefficient exhibits a maximum value with the variation of the jet velocity.