Two-dimensional bubble rising through quiescent and non-quiescent fluid: Influence on heat transfer and flow behavior

An understanding of the bubble properties, size distributions and shapes and their ability in various applications is of fundamental importance for comprehending flow dynamics and mass transfer phenomena in bubble column reactors. A large number of studies have focused on open tube bubble columns, and the knowledge concerning bubble columns is still limited. In this paper, a 2D phase field model is presented for numerical study of a bubble rising in a fluid and its influence on heat transfer parameters on a single channel. The computational model entails the Navier-Stokes equation for fluid flow and VOF(Volume of fluid) model for interface deformation and morphology. A C++ based open source software; OpenFOAM is utilized for this simulation. It is found that rising bubble can be used as an effective method for reducing thermal boundary layer and increasing Nusselt number and consequently increasing heat transfer in industrial applications. Investigating the influence of the bubble rising on the non-quiescent fluid in a vertical channel revealed that bubble rising in high Reynolds number does not have sensible effect on Nusselt number, but in low Reynolds number it show a significant enhancement in Nusselt number. Also the results predicted that bubble injection frequency has a direct effect on Nusselt number behavior.