| This thesis includes three experimental studies and three modelling approaches to selected two-phase flow Environmental Engineering systems. A two-dimensional laser flow map particle image velocimetry coupled with planar laser-induced fluorescence (PIV/PLIF) was used to study the hydrodynamic characteristics of an impinging jets bubble column, a horizontal infne multi-jets ozone contactor, and an inclined surface plunging jets aeration system. The PIV/PLIF system provided a combination of simultaneous whole-field velocity and concentration measurements of the two phases (liquid and gas) under different operating conditions for both the bubble column and the multi-jets contactor. The PLIF results were used to determine the axial liquid dispersion coefficient (DL, m2/s) for each operating condition. The overall mass transfer coefficient (kLa, s -1) was then determined. Both systems showed high ozone transfer rates with a relatively low dispersion effect compared to that of conventional ozone contactors. The third experimental study utilized the PIV system to analyze the velocity profiles of two inclined water jets intersecting on the surface of an aeration tank. The effect of the nozzle diameter, plunging angle and jets' length was evaluated. The system showed a smaller Sauter mean bubble diameter (dS, m) and higher penetration depth (zp, m) and gas holdup (epsilonG ) compared to those of vertical plunging jets systems.;The artificial neural network (ANN) modelling approach was used to characterize different types of bubble columns by predicting kLa, epsilon G, and dS. The ANN results showed very good agreement between the modelled and the measured parameters. Transient and steady-state back flow cell models (BFCM) were used successfully to model the hydrodynamic behaviour and the dissolved ozone concentration profiles of an impinging-jet ozone bubble column. Two computation fluid dynamics (CFD) models were utilized to characterize a recycled water pond and a storage reservoir. The first CFD model was used to simulate the pond's dissolved oxygen resulting from the turbulent surface plunging jets and to predict the resulting dissolved oxygen when submerged inlets were used under different operational and atmospheric conditions. The second model was employed to evaluate the effect of the internal geometry and inlet configuration on the reactor's effective contact time ( t10). |
