The role of baffles in mechanically stirred tanks is to promote the stability of power drawn by the impeller and to avoid the fluid swirling, thus enhancing mixing. The present paper numerically investigates the baffles effects in a vessel stirred by a Rushton turbine. The geometric factor of interest is the baffle inclination which is varying between 25°, 32.5°, 45°, 70° and 90° at different impeller rotational speeds. The impeller rotational direction has also been varied. The vortex size and power consumption were evaluated for each geometrical configuration. It was found that the best configuration is the baffle inclination by α = 70° at a negative angular velocity.
Youcef Kamla
,
Mohamed Bouzit
,
Houari Ameur
,
Mohammed Ilies Arab
,
Abdessalam Hadjeb
. Effect of the Inclination of Baffles on the Power Consumption and Fluid Flows in a Vessel Stirred by[J]. Chinese Journal of Mechanical Engineering, 2017
, 30(4)
: 1008
-1016
.
DOI: 10.1007/s10033-017-0158-5
[1] M S Moeini, J M Khodadadi. Energy efficiency improvement and fuel savings in water heaters using baffles. Applied Energy, 2013, 102: 520-533.
[2] V B Gawande, A S Dhoble, D B Zodpe, et al. Experimental and CFD investigation of convection heat transfer in solar air heater with reverse L-shaped ribs. Solar Energy, 2016, 131: 275-295.
[3] D Sahel, H Ameur, R Benzeguir, et al. Enhancement of heat transfer in a rectangular channel with perforated baffles. Applied Thermal Engineering, doi:10.1016/j.applthermaleng.2016.02.136.
[4] H Ameur, M Bouzit. Power consumption for stirring shear thinning fluids by two-blade impeller. Energy, 2013, 50: 326-332.
[5] J P TorrE ′, F David, Fletcher, et al. An experimental and computational study of the vortex shape in a partially baffled agitated vessel. Chemical Engineering Science, 2007, 2007, 62: 1915-1926.
[6] M Ciofalo. Turbulent flow in closed and free-surface unbaffled tanks stirred by radial impellers. Chemical Engineering Science, 1996, 51: 3557-3573.
[7] S Nagata. Mixing: Principle and applications. Wiley, New York, 1975.
[8] H Ameur, M Bouzit, M Helmaoui. Hydrodynamic study involving a Maxblend impeller with yield stress fluids. Journal of Mechanical Science and Technology, 2012, 26: 1523-1530.
[9] H Ameur, M Bouzit, A Ghenaim. Hydrodynamics in a vessel stirred by simple and double helical ribbon impellers. Central European Journal of Engineering, 2013, 3: 87-98.
[10] G B Tatterson. Fluid mixing and gas dispersion in agitated tanks. McGraw-Hill, New York, 1991.
[11] M Assirelli, W Bujalski, A Eaglesham, et al. Macro and micromixing studies in an unbaffled vessel agitated by a Rushton turbine. Chemical Engineering Science, 2008, 63: 35-46.
[12] H Ameur, M Bouzit, M Helmaoui. Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller. Chemical and Process Engineering, 2011, 32: 351-366.
[13] A Iranshahia, C Devalsa, M Henichea, et al. Hydrodynamics characterization of the Maxblend impeller. Chemical Engineering Science, 2007, 62: 3641-3653.
[14] F Strek, J Karcz. Experimental studies of power consumption for agitated vessels equipped with non-standard baffles and highspeed agitator. Chemical Engineering and Processing: Process Intensification, 1993, 32: 349-357.
[15] W M Lu, H Z Wu, M Y Ju. Effects of baffle design on the liquid mixing in an aerated stirred tank with standard Rushton turbine impellers. Chemical Engineering Science, 1997, 52(21-22): 3843-3851.
[16] S Youcefi, M Bouzit, H Ameur, et al. Effect of some design parameters on the flow fields and power consumption in a vessel stirred by a Rushton turbine. Chemical and Process Engineering, 2013, 34: 293-307.
[17] H Ameur, M Bouzit, A Ghenaim. Numerical study of the performance of multistage Scaba 6SRGT impellers for the agitation of yield stress fluids in cylindrical tanks. Journal of Hydrodynamics, 2015, 27: 436-442.
[18] I Naude. Direct simulations of impellers in a stirred tank. Contribution to the optimization of the choice of an agitator. Ph. D. Thesis, INPT, France, 1998.
[19] J Y Luo, A D Gosman, R I Issa, et al. Full flow field computation of mixing in baffled stirred vessels. Chemical Engineering Research and Design, 1993, 71: 342-344.
[20] D A Deglon, C J Meyer. CFD modelling of stirred tanks: Numerical considerations. Minerals Engineering, 2006, 19: 1059-1068.
[21] J N Haque, T Mahmud, K Roberts. Modeling turbulent flows with free surface in unbaffled agitated vessels. Industrial and Engineering Chemistry Research, 2006, 45: 2881-2891.
[22] H Wu, G K Patterson. Laser-Doppler measurements of turbulentflow parameters in a stirred mixer. Chemical Engineering Science, 1989, 44: 2207-2221.
[23] C Galleti, E Brunazzi. On the main flow features and instabilities in an unbaffled vessel agitated with an eccentrically located impeller. Chemical Engineering Science, 2008, 63: 4494-4505.
[24] J Karcz, M Major. An effect of a baffle length on the power consumption in an agitated vessel. Chemical Engineering and Processing: Process Intensification, 1998, 37: 249-56.
[25] M Ammar, Z Driss, W Chtourou, et al. Effects of baffle length on turbulent flows generated in stirred vessels. Central European Journal of Engineering, 2011, 1: 401-412.
[26] F Strek, J Karcz. Experimental determination of the optimal geometry of baffles for heat transfer in an agitated. Chemical Engineering and Processing: Process Intensification, 1991, 29: 165-172.
[27] C Dan Taca, M Paunescu. Power input in closed stirred vessels. Chemical Engineering Science, 2001, 56: 4445-4450.
