(131a) Computational Analysis of Fluid Dynamics On Corrugated Sheets of Packing

Packed columns are widely in chemical industry such as distillation and absorption. The efficiency of packed columns strongly depends on the flow behaviour of liquid inside the packing. It is very important to understand the flow behaviour in microscopic level to design the new generation of structured packing. Experiments can be done to analyse the flow behaviour which is always time consuming and expensive. With the recent computational technology developments in last two decades, CFD (Computational Fluid Dynamics) is one of the most powerful tools to investigate the flow behaviour. But this computational study has to be validated with experimental results. The researchers and industries are looking for the next generation of structured packings with better understanding of the flow behaviour in both micro and macroscopic level to improve the efficiency of the process. It is tedious to study the flow behaviour inside the complicated geometry directly. To analyse the basic and fundamental performance initially, the smooth inclined plate is considered for study. Furthermore, the validated model can be extended to other geometries. In the framework of this paper, the validated model to study the countercurrent flow behaviour in smooth inclined plate will be presented. The model will also be extended to corrugated sheet of packings and morphological comparison of liquid flow will be discussed. Initially, to validate the model, the hydrodynamic behaviour of countercurrent flow of gas-liquid on an inclined flat plate will be studied using CFD technique. Simulations are performed using the commercially available CFD tool, Fluent 6.3, ANSYS Inc. The influences of different parameters like gravity, contact angle, inclination angle and surface tension are taken into account. To study the countercurrent flow behaviour of Gas-Liquid, the Volume of Fluid (VOF) model with geometric reconstruction scheme was used. The influence of the surface tension was included by using the Continuum Surface Force (CSF) model. The detailed sensitivity study was carried out to know the influence of small changes in parameters like flow rate of liquid, viscosity and inclination angle on the velocity profile and film thickness. Further, the influence of countercurrent gas flow was included without considering the influence of mass transfer. From the simulation results, it can be seen that increasing the gas flow rate for a constant liquid flow rate, tends to increase the film thickness and also decrease the velocity. A comparison of velocity profile along the flow direction of the liquid and the film thickness from simulation and experimental study will be presented. A good agreement between CFD simulation and experiment results can be found. As a next step, the geometry resembling the two corrugated sheets of structured packing used in industrial application was developed. Two plates are arranged in opposite direction with the inclination angle of 90˚ was considered. The validated model from the previous step was extended to study the liquid flow behaviour in this new geometry. The simulations are carried out to study the flow behaviour of liquid inside the two corrugated sheets of packing. From the simulation results, the change in flow behaviour at the criss-cross junction of the two sheets can be clearly seen (eg., Fig. 1). Experimental set up to study the morphological flow behaviour of liquid in a similar corrugated sheet is under preparation. In future, the morphological comparison of the CFD simulation and the experimental study will be presented. Further, CFD study will be extended to calculate the mass transfer in the countercurrent flow.