The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Aikaterini A. Mouza - One of the best experts on this subject based on the ideXlab platform.
-
effect of organic surfactant additives on gas holdup in the pseudo Homogeneous Regime in bubble columns equipped with fine pore sparger
Chemical Engineering Science, 2010Co-Authors: A D Anastasiou, N A Kazakis, Aikaterini A. Mouza, S V ParasAbstract:Abstract New experimental data concerning the gas holdup in bubble columns equipped with porous sparger were acquired. The effect of surfactant additives on gas holdup in the pseudo-Homogeneous Regime has been studied. Three different commercial surfactants (Triton X-100®, SDS®, CTAB®) were used and four aqueous solutions of each one were employed, in order to study the effect of the surfactant concentration and type (i.e., non-ionic, anionic, cationic). A general correlation, which includes dimensionless numbers (i.e., Froude, Archimedes and Bond) as well as the geometric characteristics of the column and the sparger, can predict the gas holdup in various systems (i.e., pure substances, ionic surfactants, non-ionic surfactants) with reasonable accuracy.
-
experimental study of bubble formation at metal porous spargers effect of liquid properties and sparger characteristics on the initial bubble size distribution
Chemical Engineering Journal, 2008Co-Authors: N A Kazakis, Aikaterini A. Mouza, Spiros V. ParasAbstract:This work is a study of the effect of liquid properties and pore size on the initial bubble size distribution of a bubble column equipped with fine pore sparger. Various liquids covering a wide range of surface tension and viscosity values are employed, while the gas phase is atmospheric air. A fast video recording technique is used for both the visual observations of the phenomena occurring onto the sparger and the bubble size measurements. A new correlation regarding the prediction of the initial mean Sauter diameter of bubbles formed from porous spargers at the Homogeneous Regime has been formulated and found to be in good agreement with available data. The experiments show that the mechanisms of bubble formation as well as the initial bubble size distribution depend strongly on the liquid properties, the sparger design and the gas flow rate.
-
bubble columns with fine pore sparger operating in the pseudo Homogeneous Regime gas hold up prediction and a criterion for the transition to the heterogeneous Regime
Chemical Engineering Science, 2007Co-Authors: N A Kazakis, I D Papadopoulos, Aikaterini A. MouzaAbstract:Abstract New experimental data concerning the gas holdup in bubble columns equipped with porous sparger were acquired. The effect of liquid properties and sparger characteristic (i.e., pore size, dimensions) on gas holdup at the pseudo-Homogeneous Regime has been studied and a correlation regarding the prediction of the transition point from the pseudo-Homogeneous to the heterogeneous Regime has been proposed and found to be in good agreement with available data. Moreover, a previously proposed correlation [Mouza, A.A., Dalakoglou, G.K., Paras, S.V., 2005. Effect of liquid properties on the performance of bubble column reactors with fine pore spargers. Chemical Engineering Science 60(5), 1465–1475], for the prediction of gas holdup at the Homogeneous Regime for this type of equipment, has been modified to take into account the effect of the mean pore diameter and it is also found to be in good agreement with published data.
-
effect of liquid properties on the performance of bubble column reactors with fine pore spargers
Chemical Engineering Science, 2005Co-Authors: Aikaterini A. Mouza, G K Dalakoglou, S V ParasAbstract:This work is a study of the effect of liquid properties on the performance of bubble column reactors with fine pore spargers. Various liquids covering a range of surface tension and viscosity values are employed, while the gas phase is atmospheric air. A fast video technique is used for visual observations and, combined with image processing, is used for gas holdup and bubble size measurements. New data on average gas holdup values, bubble size distributions and Sauter diameters are presented and are consistent with existing physical models on coalescence/breakage. A correlation based on dimensionless groups for the prediction of gas holdup in the Homogeneous Regime is proposed and found to be in good agreement with available data.
T Kolb - One of the best experts on this subject based on the ideXlab platform.
-
novel gas holdup correlation for slurry bubble column reactors operated in the Homogeneous Regime
Chemical Engineering Journal, 2017Co-Authors: M Gotz, J Lefebvre, Friedemann Mors, Felix Ortloff, R Reimert, S Bajohr, T KolbAbstract:Abstract The gas holdup is an important parameter for the design of slurry bubble columns. However, there is no correlation in literature to calculate the gas holdup of such reactors for industrially relevant conditions if the reactor is operated in the Homogeneous Regime. In this article, a novel correlation for calculating the gas holdup in the Homogeneous and in the pseudo-Homogeneous Regimes is proposed. The correlation takes the relevant parameters into account: gas, liquid, and solid properties, sparger design, reactor diameter, and gas velocity. The correlation is also applicable for systems operated at elevated pressure and temperature. The correlation is based on 1199 data points, and it was developed by using the method of least squares. About two thirds of the data used were taken from literature (more than 20 research papers). The data from literature were carefully checked for confidence before using them for the correlation. > 90 % of the data points are covered by the new correlation with a relative error of less than 30 %, the standard deviation is 17.8 % and the averaged relative error is 9.5 %. Finally, the correlation was successfully validated with measurements which were not used to fit the correlation. An Excel file for using the developed correlation can be found in the Supplementary material.
-
hydrodynamics of organic and ionic liquids in a slurry bubble column reactor operated at elevated temperatures
Chemical Engineering Journal, 2016Co-Authors: M Gotz, J Lefebvre, Friedemann Mors, R Reimert, F Graf, T KolbAbstract:Abstract Hydrodynamics (e.g. gas holdup, bubble size, and flow Regime) significantly influences the performance of slurry bubble column reactors. In this work, the influence of gas, liquid, and solid phase properties on the hydrodynamics was investigated at temperatures up to 573 K and pressures up to 0.5 MPa. Amongst the investigated liquids, the hydrodynamic behavior of ionic liquids at elevated temperatures is ruled by their high surface tension leading to small gas holdups and formation of large bubbles compared with heat transfer oils. The solids strongly influence the hydrodynamics but their effects are still not fully understood. Therefore, the behavior of solids was investigated in this work. The results indicate that small concentrations of fine particles reduce bubble coalescence and subsequently stabilize the Homogeneous Regime. However, the primary bubble size increases with the addition of solids. Furthermore, it has been shown that the gas holdup decreases with an increasing difference between particle and liquid density.
N A Kazakis - One of the best experts on this subject based on the ideXlab platform.
-
effect of organic surfactant additives on gas holdup in the pseudo Homogeneous Regime in bubble columns equipped with fine pore sparger
Chemical Engineering Science, 2010Co-Authors: A D Anastasiou, N A Kazakis, Aikaterini A. Mouza, S V ParasAbstract:Abstract New experimental data concerning the gas holdup in bubble columns equipped with porous sparger were acquired. The effect of surfactant additives on gas holdup in the pseudo-Homogeneous Regime has been studied. Three different commercial surfactants (Triton X-100®, SDS®, CTAB®) were used and four aqueous solutions of each one were employed, in order to study the effect of the surfactant concentration and type (i.e., non-ionic, anionic, cationic). A general correlation, which includes dimensionless numbers (i.e., Froude, Archimedes and Bond) as well as the geometric characteristics of the column and the sparger, can predict the gas holdup in various systems (i.e., pure substances, ionic surfactants, non-ionic surfactants) with reasonable accuracy.
-
experimental study of bubble formation at metal porous spargers effect of liquid properties and sparger characteristics on the initial bubble size distribution
Chemical Engineering Journal, 2008Co-Authors: N A Kazakis, Aikaterini A. Mouza, Spiros V. ParasAbstract:This work is a study of the effect of liquid properties and pore size on the initial bubble size distribution of a bubble column equipped with fine pore sparger. Various liquids covering a wide range of surface tension and viscosity values are employed, while the gas phase is atmospheric air. A fast video recording technique is used for both the visual observations of the phenomena occurring onto the sparger and the bubble size measurements. A new correlation regarding the prediction of the initial mean Sauter diameter of bubbles formed from porous spargers at the Homogeneous Regime has been formulated and found to be in good agreement with available data. The experiments show that the mechanisms of bubble formation as well as the initial bubble size distribution depend strongly on the liquid properties, the sparger design and the gas flow rate.
-
bubble columns with fine pore sparger operating in the pseudo Homogeneous Regime gas hold up prediction and a criterion for the transition to the heterogeneous Regime
Chemical Engineering Science, 2007Co-Authors: N A Kazakis, I D Papadopoulos, Aikaterini A. MouzaAbstract:Abstract New experimental data concerning the gas holdup in bubble columns equipped with porous sparger were acquired. The effect of liquid properties and sparger characteristic (i.e., pore size, dimensions) on gas holdup at the pseudo-Homogeneous Regime has been studied and a correlation regarding the prediction of the transition point from the pseudo-Homogeneous to the heterogeneous Regime has been proposed and found to be in good agreement with available data. Moreover, a previously proposed correlation [Mouza, A.A., Dalakoglou, G.K., Paras, S.V., 2005. Effect of liquid properties on the performance of bubble column reactors with fine pore spargers. Chemical Engineering Science 60(5), 1465–1475], for the prediction of gas holdup at the Homogeneous Regime for this type of equipment, has been modified to take into account the effect of the mean pore diameter and it is also found to be in good agreement with published data.
S V Paras - One of the best experts on this subject based on the ideXlab platform.
-
effect of organic surfactant additives on gas holdup in the pseudo Homogeneous Regime in bubble columns equipped with fine pore sparger
Chemical Engineering Science, 2010Co-Authors: A D Anastasiou, N A Kazakis, Aikaterini A. Mouza, S V ParasAbstract:Abstract New experimental data concerning the gas holdup in bubble columns equipped with porous sparger were acquired. The effect of surfactant additives on gas holdup in the pseudo-Homogeneous Regime has been studied. Three different commercial surfactants (Triton X-100®, SDS®, CTAB®) were used and four aqueous solutions of each one were employed, in order to study the effect of the surfactant concentration and type (i.e., non-ionic, anionic, cationic). A general correlation, which includes dimensionless numbers (i.e., Froude, Archimedes and Bond) as well as the geometric characteristics of the column and the sparger, can predict the gas holdup in various systems (i.e., pure substances, ionic surfactants, non-ionic surfactants) with reasonable accuracy.
-
effect of liquid properties on the performance of bubble column reactors with fine pore spargers
Chemical Engineering Science, 2005Co-Authors: Aikaterini A. Mouza, G K Dalakoglou, S V ParasAbstract:This work is a study of the effect of liquid properties on the performance of bubble column reactors with fine pore spargers. Various liquids covering a range of surface tension and viscosity values are employed, while the gas phase is atmospheric air. A fast video technique is used for visual observations and, combined with image processing, is used for gas holdup and bubble size measurements. New data on average gas holdup values, bubble size distributions and Sauter diameters are presented and are consistent with existing physical models on coalescence/breakage. A correlation based on dimensionless groups for the prediction of gas holdup in the Homogeneous Regime is proposed and found to be in good agreement with available data.
M Gotz - One of the best experts on this subject based on the ideXlab platform.
-
novel gas holdup correlation for slurry bubble column reactors operated in the Homogeneous Regime
Chemical Engineering Journal, 2017Co-Authors: M Gotz, J Lefebvre, Friedemann Mors, Felix Ortloff, R Reimert, S Bajohr, T KolbAbstract:Abstract The gas holdup is an important parameter for the design of slurry bubble columns. However, there is no correlation in literature to calculate the gas holdup of such reactors for industrially relevant conditions if the reactor is operated in the Homogeneous Regime. In this article, a novel correlation for calculating the gas holdup in the Homogeneous and in the pseudo-Homogeneous Regimes is proposed. The correlation takes the relevant parameters into account: gas, liquid, and solid properties, sparger design, reactor diameter, and gas velocity. The correlation is also applicable for systems operated at elevated pressure and temperature. The correlation is based on 1199 data points, and it was developed by using the method of least squares. About two thirds of the data used were taken from literature (more than 20 research papers). The data from literature were carefully checked for confidence before using them for the correlation. > 90 % of the data points are covered by the new correlation with a relative error of less than 30 %, the standard deviation is 17.8 % and the averaged relative error is 9.5 %. Finally, the correlation was successfully validated with measurements which were not used to fit the correlation. An Excel file for using the developed correlation can be found in the Supplementary material.
-
hydrodynamics of organic and ionic liquids in a slurry bubble column reactor operated at elevated temperatures
Chemical Engineering Journal, 2016Co-Authors: M Gotz, J Lefebvre, Friedemann Mors, R Reimert, F Graf, T KolbAbstract:Abstract Hydrodynamics (e.g. gas holdup, bubble size, and flow Regime) significantly influences the performance of slurry bubble column reactors. In this work, the influence of gas, liquid, and solid phase properties on the hydrodynamics was investigated at temperatures up to 573 K and pressures up to 0.5 MPa. Amongst the investigated liquids, the hydrodynamic behavior of ionic liquids at elevated temperatures is ruled by their high surface tension leading to small gas holdups and formation of large bubbles compared with heat transfer oils. The solids strongly influence the hydrodynamics but their effects are still not fully understood. Therefore, the behavior of solids was investigated in this work. The results indicate that small concentrations of fine particles reduce bubble coalescence and subsequently stabilize the Homogeneous Regime. However, the primary bubble size increases with the addition of solids. Furthermore, it has been shown that the gas holdup decreases with an increasing difference between particle and liquid density.