The flow pattern and entropy generation in an axial inlet cyclone with reflux cone and gaps in the vortex finder

This paper aimed at studying the contribution of the reflux cone and the gaps in the vortex finder to the reduction of energy consumption in the cyclones. The flow field was calculated using Reynolds Stress Model (RSM). Based on the numerical investigations, the entropy generation analysis method was used to explain the mechanism of energy consumption inside cyclone separators. The regional entropy generation in four parts viz. the outlet pipe, the inlet part, the region around vortex finder and the region below vortex finder was calculated and analyzed to identify the zones where the energy is largely consumed. The results show that the reflux cone and the gaps help reduce the entropy generation in the gas-outlet pipe, in the regions around and under the vortex finder, whereas increase the entropy generation in the inlet part. In addition, the reflux cone restrains the reflux flow and mainly reduces the entropy generation in the region around the vortex finder. The gaps reduce the flow rate under the vortex finder and mainly reduce the entropy generation in that region.

[1]  A. Johansson,et al.  An algebraic model for nonisotropic turbulent dissipation rate in Reynolds stress closures , 1990 .

[2]  Z. Ji,et al.  Development of a cyclone separator with high efficiency and low pressure drop in axial inlet cyclones , 2014 .

[3]  W. C. Reynolds,et al.  Asymptotic near‐wall stress dissipation rates in a turbulent flow , 1983 .

[4]  H. Herwig,et al.  Entropy production calculation for turbulent shear flows and their implementation in cfd codes , 2005 .

[5]  Miroslav Soos,et al.  Determination of maximum turbulent energy dissipation rate generated by a rushton impeller through large eddy simulation , 2013 .

[6]  Shi Ming-xian.  Experimental and numerical study of gas flow in PSC type cyclone tube , 2006 .

[7]  A. Hoekstra,et al.  Gas flow field and collection efficiency of cyclone separators , 2000 .

[8]  N. A. Tsochatzidis,et al.  Methods help remove black powder from gas pipelines , 2007 .

[9]  M.R.H. Nobari,et al.  A numerical investigation of entropy generation in the entrance region of curved pipes at constant w , 2011 .

[10]  Chris Lacor,et al.  Optimization of the cyclone separator geometry for minimum pressure drop using mathematical models and CFD simulations , 2010 .

[11]  A. Behzadmehr,et al.  Numerical study of flow parameters and entropy generation on a centrifugal fan , 2009 .

[12]  H. Shalaby,et al.  Comparative study of the continuous phase flow in a cyclone separator using different turbulence models , 2005 .

[13]  Arman Raoufi,et al.  Numerical simulation and optimization of fluid flow in cyclone vortex finder , 2008 .

[14]  Hesham M. El-Batsh,et al.  Improving cyclone performance by proper selection of the exit pipe , 2013 .

[15]  Murray E. Moore,et al.  Performance modeling of single-inlet aerosol sampling cyclones , 1993 .

[16]  Shi Ming-xian.  Performance and application of a cyclone at high temperature and high pressure , 2006 .

[17]  C. Fredriksson.  Exploratory experimental and theoretical studies of cyclone gasification of wood powder , 1999 .

[18]  H. Herwig,et al.  Direct and indirect methods of calculating entropy generation rates in turbulent convective heat transfer problems , 2006 .

[19]  T. G. Chuah,et al.  A CFD study of the effect of cone dimensions on sampling aerocyclones performance and hydrodynamics , 2006 .

[20]  Suad Jakirlić,et al.  A new approach to modelling near-wall turbulence energy and stress dissipation , 2002, Journal of Fluid Mechanics.

[21]  Hakan F. Oztop,et al.  A review on entropy generation in natural and mixed convection heat transfer for energy systems , 2012 .

[22]  Zhongli Ji,et al.  Entropy generation analysis on cyclone separators with different exit pipe diameters and inlet dimensions , 2015 .

[23]  F. Boysan,et al.  Advances in Cyclone Modelling Using Unstructured Grids , 2000 .

[24]  Aibing Yu,et al.  Particle scale modelling of the multiphase flow in a dense medium cyclone: Effect of fluctuation of solids flowrate , 2012 .

[25]  Alex C. Hoffmann,et al.  Gas Cyclones and Swirl Tubes: Principles, Design, and Operation , 2007 .

[26]  K. Elsayed,et al.  The effect of cyclone vortex finder dimensions on the flow pattern and performance using LES , 2013 .

[27]  Aibing Yu,et al.  Particle scale modelling of the multiphase flow in a dense medium cyclone: Effect of vortex finder outlet pressure , 2012 .

[28]  K. Elsayed,et al.  The effect of cyclone inlet dimensions on the flow pattern and performance , 2011 .

[29]  Rached Ben-Mansour,et al.  Entropy generation in developing laminar fluid flow through a circular pipe with variable properties , 2005 .

[30]  J. Derksen,et al.  An experimental and numerical study of turbulent swirling flow in gas cyclones , 1999 .

[31]  A. Bıyıkoğlu.  Entropy generation due to flow across the abrupt contraction of pipe joints , 2009 .

[32]  Aydın Durmuş,et al.  Effect of propeller type swirl generators on the entropy generation and efficiency of heat exchangers , 2007 .

[33]  S. A. Morsi,et al.  An investigation of particle trajectories in two-phase flow systems , 1972, Journal of Fluid Mechanics.

[34]  H. Herwig,et al.  Local entropy production in turbulent shear flows: a high-Reynolds number model with wall functions , 2004 .

[35]  Johannes Janicka,et al.  Assessment of Unsteady RANS in Predicting Swirl Flow Instability Based on LES and Experiments , 2004 .

[36]  A. Bejan,et al.  Entropy Generation Through Heat and Fluid Flow , 1983 .

[37]  H. S. Kim,et al.  Characteristics of the collection efficiency for a cyclone with different vortex finder shapes , 2004 .

[38]  Todd A. Jankowski,et al.  Minimizing entropy generation in internal flows by adjusting the shape of the cross-section , 2009 .

[39]  M. T. Landahl,et al.  Turbulence and random processes in fluid mechanics , 1992 .