CFD STUDY OF SINGLE PHASE FLOW AROUND SPHERICAL PARTICLES

Abstract

The transport processes occurring around spherical particles is of fundamental importance to numerous scientific fields. An understanding of such phenomena is of relevance to flow phenomena within packed beds typically encountered in -chemical reaction engineering, as well as single and multiphase flow phenomena within porous media such as rocks and soil. Packed bed reactors with multiphase flow have been used in a large number of processes in refinery, fine chemicals and biochemical operations. This has prompted extensive studies of mathematical and physical models for these systems. In this present work a qualitative study of single phase flow around spherical particles has been made. For this study simulations for the laminar model and K-c model have been carried out using CFD code FLUENT 6.2.16 and results of these simulations have been analyzed. The system considered for this study is a tubular column of diameter of 30 mm and length of 300 mm. This column consists of six layers of spherical particles of 5 mm diameter. Each layer has four particles at a constant distance of 2 mm and the distance between the layers is also 2 mm. The first layer is placed at a distance of 140 mm from the inlet. Results obtained from these simulations shows that the 140 mm inlet length is not sufficient for the development of the fully developed flow except for 9.8 m/s of inlet velocity. The velocity between the two adjacent particles is like a jet and low in the remaining part of the packed bed is predicted accurately. Velocity near the wall is found to be of zero value. Pressure fluctuations are high between the wall and the adjacent particles and between the two adjacent particles. The pressure distribution is constant in the rest region of the bed which is free from the influence of the surface boundary of the particles. iii Eddy formation is found between the two adjacent particles and the intensity of the is found to be lower in the case of laminar model but in the case of K-c model the eddies are found to be of higher intensity. iv