TY - JOUR ID - 15161 TI - Effects of Height to Diameter Ratio and Aeration rate on Liquid Mixing and Hydrodynamic Properties in a Bubble Column JO - Iranian Journal of Chemical Engineering(IJChE) JA - IJCHE LA - en SN - 1735-5397 Y1 - 2009 PY - 2009 VL - 6 IS - 3 SP - 46 EP - 56 KW - Bubble column KW - Overall gas holdup KW - Residence time distribution KW - Axial Dispersion Coefficient KW - Mixing time DO - N2 - "> Experimental measurements of overall gas holdup (εg), residence time distribution (RTD) and liquid mixing time (tm) have been carried out in an air-water system in a 17 lit bubble column with an 11 cm diameter, over a wide range of superficial gas velocity (0.14-1.46 ms-1) and height to diameter ratio (1.36-8.84). The bed expansion method was used to obtain holdup values and the change of slope related to εg versus superficial gas velocity (Usg) indicated the transition point from homogeneous to heterogeneous regime at Usg= 0.7-0.9 ms-1. Besides, the experiments illustrated that H/D ratio had no effect on holdup values. The axial dispersion model was used with semi-closed boundary conditions for prediction of RTD, and hence, the axial dispersion coefficients (Dax). Moreover, fitting results of the model and experimental RTD curves achieved from tracer injection method attained the model parameter, Dax , in three H/D ratios of 4.73, 6.36 and 8.84. Results showed that an elevation in H/D ratio, caused a rise in D ax. On the other hand, the mixing time data declined with an increase in Usg; however enhancement of H/D ratio caused an increase in tm. UR - https://www.ijche.com/article_15161.html L1 - https://www.ijche.com/article_15161_ec8c0dbc35be15686501f350cda03b94.pdf ER -