The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
P V Khan - One of the best experts on this subject based on the ideXlab platform.
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experimental observation of the maximum Bubble Diameter in non stationary temperature field of subcooled boiling water flow
International Journal of Heat and Mass Transfer, 2018Co-Authors: A. A. Levin, P V KhanAbstract:Abstract This paper presents results of the experimental study of the subcooled boiling flow on the surface of the vertical cylindrical steel heater. The initial stages of formation of the fully developed nucleate boiling were investigated over the unsteady stepwise heat flux range from 0.56 to 1.76 MW/m2. The field temperature of heated liquid layers at the moment of the Bubble departure was described by numerical modeling under nonstationary conditions. A high-speed digital video camera was used to capture the Bubble dynamics. The effects of heat release conditions and inlet water temperature on the Bubble maximum Diameter and nucleation frequency were studied. We found that the increased heat flux results in reduction of the maximum Diameter at non-stationary heat release. Calculations on the basis of prediction models showed that the non-stationary nucleate boiling data cannot be generalized using the models developed by Prodanovic et al. (2002) and Song (2016) with the coefficients obtained for the stationary boiling. However, the heat balance approach to calculation of the Bubble maximum Diameter proved to be promising, and the correlation between the Bubble Diameter and the overheated layer thickness was verified.
Badie I Morsi - One of the best experts on this subject based on the ideXlab platform.
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gas holdup and Bubble size behavior in a large scale slurry Bubble column reactor operating with an organic liquid under elevated pressures and temperatures
Chemical Engineering Journal, 2007Co-Authors: Arsam Behkish, Romain Lemoine, Laurent Sehabiague, Rachid Oukaci, Badie I MorsiAbstract:Abstract The holdups of small and large gas Bubbles, Bubble size distribution and the Sauter-mean Bubble Diameter were measured for N 2 and He in isoparaffinic organic liquid mixture (Isopar-M) in the absence and presence of Alumina powder under various pressures (0.67–3 MPa), temperatures (300–473 K), superficial gas velocities (0.07–0.39 m/s), and solid concentrations (0–20 vol.%) in a large-scale Bubble column and slurry Bubble column reactor (SBCR) (0.29 m Diameter, 3 m height). The gas holdup was measured using the manometric method and the Bubble size distribution, and Sauter-mean Bubble Diameter were obtained using the dynamic gas disengagement (DGD) technique and the photographic method. The experimental data showed that the total gas holdup increased with pressure and superficial gas velocity due to the increase of gas momentum which shifted the Bubble size distribution towards smaller gas Bubbles. The total gas holdup was also found to increase with temperature due to the decrease of liquid viscosity and surface tension. Increasing the solid concentration, on the other hand, resulted in a significant decrease of the total gas holdup and significantly increased the Sauter-mean Bubble Diameter. The online monitoring of the swarm using the high-speed camera showed a decrease of the froth stability in the reactor with increasing solid concentration and temperature which were responsible for the decrease of the total gas holdup.
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Hydrodynamic and Mass-Transfer Characteristics in Organic Liquid Mixtures in a Large-Scale Bubble Column Reactor for the Toluene Oxidation Process
Industrial & Engineering Chemistry Research, 2004Co-Authors: Romain Lemoine, And Arsam Behkish, Badie I MorsiAbstract:The gas holdup (eG), Sauter mean Bubble Diameter (dS), and Bubble size distribution, as well as the volumetric mass-transfer coefficient (kLa), gas−liquid interfacial area (a), and mass-transfer coefficient (kL), of N2 and air were measured in a large-scale (0.316-m inside Diameter, 2.8-m height) Bubble column reactor (BCR) in toluene and its mixtures (toluene−benzoic acid−benzaldehyde) under a wide range of pressure (0.2−0.8 MPa) and superficial gas velocities (0.06−0.14 m/s). The kLa data were determined using the transient physical gas absorption technique, whereas the Bubble size distributions as well as the Sauter mean Bubble Diameters were obtained using the dynamic gas disengagement technique. The gas holdup values were measured employing the manometric method with two differential pressure cells located at different positions in the BCR. From the experimental gas holdup, Sauter mean Bubble Diameter, and kLa results, a and kL were extracted under various operating conditions. The central composite ...
A. A. Levin - One of the best experts on this subject based on the ideXlab platform.
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experimental observation of the maximum Bubble Diameter in non stationary temperature field of subcooled boiling water flow
International Journal of Heat and Mass Transfer, 2018Co-Authors: A. A. Levin, P V KhanAbstract:Abstract This paper presents results of the experimental study of the subcooled boiling flow on the surface of the vertical cylindrical steel heater. The initial stages of formation of the fully developed nucleate boiling were investigated over the unsteady stepwise heat flux range from 0.56 to 1.76 MW/m2. The field temperature of heated liquid layers at the moment of the Bubble departure was described by numerical modeling under nonstationary conditions. A high-speed digital video camera was used to capture the Bubble dynamics. The effects of heat release conditions and inlet water temperature on the Bubble maximum Diameter and nucleation frequency were studied. We found that the increased heat flux results in reduction of the maximum Diameter at non-stationary heat release. Calculations on the basis of prediction models showed that the non-stationary nucleate boiling data cannot be generalized using the models developed by Prodanovic et al. (2002) and Song (2016) with the coefficients obtained for the stationary boiling. However, the heat balance approach to calculation of the Bubble maximum Diameter proved to be promising, and the correlation between the Bubble Diameter and the overheated layer thickness was verified.
Ryszard Pohorecki - One of the best experts on this subject based on the ideXlab platform.
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Bubble Diameter correlation via numerical experiment
Chemical Engineering Journal, 2005Co-Authors: Ryszard Pohorecki, Władysław Moniuk, P. Bielski, Paweł Sobieszuk, G. DąbrowieckiAbstract:Abstract A numerical experiment has been carried out to find a theoretically sound correlation relating mean Bubble Diameter in the main section of a Bubble column to the liquid physicochemical properties (density, viscosity, surface tension), and the superficial gas velocity. A correlation has been proposed in the form: d 32 = 0.289 ρ L − 0.552 μ L − 0.048 σ 0.442 U G − 0.124 or, in an approximate, dimensionless form: F r = 0.6 U G 4 ρ L g σ 1 / 2 The values obtained from the above correlations are in good agreement with experimental values, obtained for seven organic liquids.
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Hydrodynamics of a Bubble column under elevated pressure
Chemical Engineering Science, 1999Co-Authors: Ryszard Pohorecki, Władysław Moniuk, Artur ZdrójkowskiAbstract:Abstract Measurements of Bubble Diameter and gas holdup for the nitrogen–water system were carried out in a vertical pilot plant column 0.3 m Diameter and 4 m height. The process parameters were varied in the range: temperature 30–160°C, pressure 0.1–1.1 MPa, dry gas flow rate 0.02–0.12 kg/m 2 s (saturated superficial gas velocity 0.002–0.020 m/s). Making use of the experimental values of the gas holdup and Bubble Diameter the values of interfacial area were calculated.
Hajime Akimoto - One of the best experts on this subject based on the ideXlab platform.
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model development for Bubble turbulent diffusion and Bubble Diameter in large vertical pipes
Journal of Nuclear Science and Technology, 2001Co-Authors: Akira Ohnuki, Hajime AkimotoAbstract:Multi-dimensional analyses have been expected recently with expanding computation resources for gas-liquid two- phase flow analyses of advanced nuclear systems such as passive safety systems and natural-circulation-type reactors. However, the applicability of previous constitutive equations for multi-dimensional analyses has not been fully investigated especially for the effects of flow path scale because the equations have been assessed for small-scale experiments. In this study, we analyzed the scale effects by the multi-dimensional two-fluid model code using data in 38 mm and 200 mm Diameter pipes. We clarified a key-parameter to model the scale effects and developed models for the effects on phase distribution. The scale effects can be classified by the relative relationship between Bubble Diameter db and turbulent length scale lT . Bubble-induced turbulence is increased under that db is smaller than lT and Bubble coalescence is predominated rather than breakup under that lT is about three times large...
