Numerical Simulation And Investigation Of Single CO₂ Bubble Behavior In Ionic Liquids

Bubble column reactors are one of the type of that equipment which are used to deal multi-fluid systems and it is broadly used in chemical industries because of their exact mass transfer, heat transfer and easy operating conditions. However, in bubble column the motion and behavior of bubble is very key factor for improving these systems during complex conditions such high viscosity and density.This study has been conducted in two parts. The first part consists of Eulerian multiphase modeling of air-water system in a 3-D rectangular bubble column in which water and air are served to be primary and secondary phases respectively. In this study turbulence is modeled using standard k-? model. The closure models such as virtual mass, drag and lift are enabled in the numerical setup to acquire a proper coupling between the phases. The objective of this study is set in accordance with the prediction of flow field generated at different operating conditions and water axial velocity's dependence on air superficial velocity, aspect ratio of column and air sparger has been observed also. The single bubble behavior in stagnant liquid should also be investigated to elaborate the fluid dynamic performance in a bubble column, which can give an efficient tool for designing a bubble column. Variety of key parameters of bubble column are available which are thought of having great importance regarding their design and scale-up. Since last many years these devices have been attracting the attention of many researchers due to number of their qualities and versatility. In present study simulation of 2-D rectangular bubble column is done which involves movement of a single bubble through a stagnant liquid. For this purpose, commonly used CFD tool ANSYS Fluent 16.0 is applied. The geometry is built and then meshing is done in GAMBIT 2.3.1. Presently the multiphase modeling is made possible using VOF model coupled with level set method. And turbulence is disabled. For validation the actual simulation case is consisting of air bubble and water liquid, whose result of bubble rising velocity is compared with already published work. As a consequence, a good agreement thus is obtained. Once the model is validated then further simulations are accomplished with multiphase systems consisting of carbon dioxide bubble and two ionic liquids (ILs) [Bmim][BF4] and [Bmim][PF6] to obtain a parametric study, about the influence of various factors such as size of bubble, viscosity of liquid and width of column on bubble rise velocity. In this work the single bubble in column is patched instead of being entered at certain velocity that intends to follow an upward path with variable velocity under the influence of buoyancy force. Also the additional aspect of this work is study of velocity field developed due to phase-phase interaction.