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The effects of liquid velocity, nozzle diameter, gas chamber volume and gas flow rate on volumes, shapes and growth curves of bubbles formed at a nozzle submerged in a cocurrently upward flowing liquid in a bubble column were expe...
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The effects of liquid velocity, nozzle diameter, gas chamber volume and gas flow rate on volumes, shapes and growth curves of bubbles formed at a nozzle submerged in a cocurrently upward flowing liquid in a bubble column were exper- imentally investigated. The bubble volume decreases with increasing liquid flow velocity. The effect of liquid flow velocity on the volume of bubble increase with an increase in the gas flow rate. To simulate bubble formation at a nozzle submerged in cocurrently upward flowing liquid, a revised non-spherical bubble ormation model was proposed.
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Experimental measurements for the axial and radial variations in gas holdup, axial and radial dispersion coefficients, volumetric gas-liquid mass transfer coefficient and liquid phase circulation velocity in a cone of a large diam...
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Experimental measurements for the axial and radial variations in gas holdup, axial and radial dispersion coefficients, volumetric gas-liquid mass transfer coefficient and liquid phase circulation velocity in a cone of a large diameter (122 cm) jet bubble column are presented. Two diameters of the inlet nozzle, namely 10.16 cm and 15.24 cm, three superficial gas velocities (based on cylinder diameter), 3 cm/sec, 6 cm/sec and 8 cm/sec and two superficial liquid velocities, 0.3 cm/sec and 0.6 cm/sec, are examined. The experimental data are obtained for two different bed heights.The experimental data showed significant axial and radial variations in the gas holdup. The volumetric average gas holdup was higher at higher gas velocity and larger nozzle diameter and somewhat higher at lower liquid velocity. The axial dispersion was high while the radial dispersion was low. The volumetric gas-liquid mass transfer coefficient was larger at higher gas velocity and larger nozzle diameter. The liquid recirculation begins only at the upper end of the cone. In general, experimental data indicate that a jet bubble column provides a high degree of mixing and transport rates.
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Longitudinal concentration distributions were measured under various conditions in the case of oxygen absorption in standard and multistage slurry bubble columns. By measuring the time at the maximum of residence time distribution...
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Longitudinal concentration distributions were measured under various conditions in the case of oxygen absorption in standard and multistage slurry bubble columns. By measuring the time at the maximum of residence time distribution in the multistage slurry bubble column and by using the relationships between gas holdup (epsilon(G) = 0.02 similar to 0.06), volumetric mass transfer coefficient, and the mean superficial gas velocity ((u) over bar(G) = 0.7 similar to 2.0 cm/s) in a standard slurry bubble column, the concentration distributions of dissolved oxygen in the multistage slurry bubble column could be estimated by the back flow model, in which perfect mixing in each stage and back flow between stages were assumed. The concentration distributions were expressed adequately by the back flow model. [References: 16]
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The creation of liquid-gas dispersions places very high demands on the process technology, which requires knowledge of bubble formation mechanisms. To extend the range of validity of the current calculation models to larger viscos...
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The creation of liquid-gas dispersions places very high demands on the process technology, which requires knowledge of bubble formation mechanisms. To extend the range of validity of the current calculation models to larger viscosity differences, the bubble formation mechanisms for the media combination oil/air are investigated. Compared to the media combination water/air, significant differences occur. The results obtained here will make it possible to design bubble columns in a more targeted manner in the future, which will lead to savings in resources and energy of industrial test stands.
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The bubble shape is a required parameter in the modeling and design of multiphase reactors. This communication contributes to the broader discussion and closes the knowledge gap by providing a practical correlation for the bubble ...
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The bubble shape is a required parameter in the modeling and design of multiphase reactors. This communication contributes to the broader discussion and closes the knowledge gap by providing a practical correlation for the bubble shape. The correlation is based on a very large experimental dataset, encompassing a wide range of Morton numbers (Log(10)(Mo) in the range of -10.8 and 2.3), flow conditions (single bubbles and dense bubbly flows) and considering both gravity-driven flows and flows with an extraexternal pressure gradient (counter-current flows). The experimental data were post-processed to derive a simple and physics-based correlation, relating the bubble aspect ratio to the bubble Reynolds and Eotyos numbers. This correlation provides a more accurate description and covers a wider range of applicability compared with literature correlations. As such, it can be helpful in the estimation of the interfacial area and velocity of a dispersed phase rising in a continuous phase. (C) 2019 Elsevier Ltd. All rights reserved.
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Flow properties of gas phase reactants such as size, rising velocity and frequency were investigated in simulated three-phase slurry bubble column reactors. Effects of gas velocity, reactor pressure, liquid viscosity, solid conten...
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Flow properties of gas phase reactants such as size, rising velocity and frequency were investigated in simulated three-phase slurry bubble column reactors. Effects of gas velocity, reactor pressure, liquid viscosity, solid content in the slurry phase and column diameter on the flow properties of a gas reactant were determined. The multiple effects of operating variables on the bubble properties were well visualized by means of contour maps. The effects of operating variables on the flow properties of bubbles changed with changing column diameter of the reactor. The size, rising velocity and frequency of reactant gas bubbles were well correlated in terms of operating variables including column diameter of the reactor.
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This paper discusses the role of the gas injection pattern on the large scale structures in a homogeneous pseudo-2D bubble column operated at relatively high gas hold-ups up to 8% Seven cases with different inlet configuration hav...
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This paper discusses the role of the gas injection pattern on the large scale structures in a homogeneous pseudo-2D bubble column operated at relatively high gas hold-ups up to 8% Seven cases with different inlet configuration have been studied experimentally by Harteveld et al. Each of these cases has been simulated using a (parallel) Euler-Lagrange model developed by Darmana et al. The presence of coherent structures for both uniform and non-uniform gas injection is studied. Furthermore, the influence of the gas injection pattern on the dynamics is investigated, while the statistical (average and fluctuating) quantities are compared with the PIV/PTV and LDA measurement data of Harteveld et al. The results show that the model resembles the observed experimental flow structures to a large extent.
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In the experiment, bubbles were generated from the brass nozzle with the inner diameter of 1.1 mm submerged in the glass tank (400 × 400 × 700 mm) filled with distillated water. Pressure fluctuations and signal from the laser-ph...
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In the experiment, bubbles were generated from the brass nozzle with the inner diameter of 1.1 mm submerged in the glass tank (400 × 400 × 700 mm) filled with distillated water. Pressure fluctuations and signal from the laser-phototransistor sensor were recorded simultaneously. The movement of bubble wall was measured using a high speed camera and image processing technique. Results of analysis of images have been correlated with pressure and laser-phototransistor signals. In the analysis the Fourier spectrum, wavelet spectrum and non-linear methods (mutual information, attractor reconstruction, largest Lyapunov exponent and correlation dimension) have been used.The three applied in the paper techniques of measurement of dynamical properties of bubbling allow us to discuss in detail the mechanisms of different chaotic behaviors of bubbling. Two ranges of the air volume flow rate with different kinds of bubble chaotic behaviors have been identified. For the air volume flow rate less than 0.2 1/min the air pressure chaotic fluctuations do not cause the significant chaotic changes of bubble departure frequencies. When the air volume flow rate increases above the 0.21/min, the interaction between departing bubbles causes nonperiodic bubble wall movement, and then the appearance of chaotic changes of bubble departure frequency.
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In this study, the simulation of microorganism ability for the production of poly-β-hydroxybutyrate (PHB) from natural gas (as a carbon source) was carried out. Based on the Taguchi algorithm, the optimum situations for PHB produ...
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In this study, the simulation of microorganism ability for the production of poly-β-hydroxybutyrate (PHB) from natural gas (as a carbon source) was carried out. Based on the Taguchi algorithm, the optimum situations for PHB production from natural gas in the columnar bubble reactor with 30 cm length and 1.5 cm diameter at a temperature of 32 °C was evaluated. So, the volume ratio of air to methane of 50:50 was calculated. The simulation was carried out by COMSOL software with two-dimensional symmetric mode. Mass transfer, momentum, density-time, and density-place were investigated. The maximum production of biomass concentration reached was 1.63 g/L, which shows a 10% difference in contrast to the number of experimental results. Furthermore, the consequence of inlet gas rate on concentration and gas hold up was investigated Andres the simulation results were confirmed to experimental results with less than 20% error.
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This paper studies the influence of ionic surfactants on overall gas hold-up in air-distilled water dispersed system.Experimental results were correlated with bubble size distribution and flow structures.The physical model of Liep...
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This paper studies the influence of ionic surfactants on overall gas hold-up in air-distilled water dispersed system.Experimental results were correlated with bubble size distribution and flow structures.The physical model of Lieppe(1988)was used in order to explain these results.Adsorption of ionic surfactants on the bubble surface generates an electrostatic field equivalent to an electrolyte solution and this field was proved to be important for overall gas hold-up.The dependence of gas hold-up on the superficial gas velocity showed the change of flow structures in bubble columns.
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