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Experimental and numerical study of turbulent mixing in a model of a polymerization reactor
Xavier Ingle`s,Jordi Pallares,Marı´a Teresa Larre,Luis Me´ndez,Francesc Xavier Grau 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4
In this study the turbulent mixing in a model of a polymerization reactor is analyzed experimentally and numerically. The model corresponds to a zone of an autoclave reactor equipped with a stirrer. Two different configurations of the stirrer, with different arrangement of the paddles, have been considered. The mixing process has been monitored by following the time-evolution of injections of a passive scalar through the different inlets of the model. The time-evolution of the mixing quality in a laboratory scale model of the reactor has been measured using water and the Planar Laser Induced Fluorescence (PLIF)technique. Numerical simulations of the flow and of the mixing processes were carried out and results of the evolution of the mixing are compared successfully with measurements. The mixing processes are dominated by the flow topology generated by the rotation of the stirrer. Superimposed to the tangential flow, secondary flows divide the length of the reactor in different zones. It has been found that macro mixing in each individual zone is a relatively fast process and that the mixing rates within each zone are very similar. However, the mixing rate between different zones is a relatively slow process.
Cito, Salvatore,Ahn, Yeh-Chan,Pallares, Jordi,Duarte, Rodrigo Martinez,Chen, Zhongping,Madou, Marc,Katakis, Ioanis Springer-Verlag 2012 Microfluidics and Nanofluidics Vol.13 No.2
<P>Capillary-driven flow (CD-flow) in microchannels plays an important role in many microfluidic devices. These devices, the most popular being those based in lateral flow, are becoming increasingly used in health care and diagnostic applications. CD-flow can passively pump biological fluids as blood, serum or plasma, in microchannels and it can enhance the wall mass transfer by exploiting the convective effects of the flow behind the meniscus. The flow behind the meniscus has not been experimentally identified up to now because of the lack of high-resolution, non-invasive, cross-sectional imaging means. In this study, spectral-domain Doppler optical coherence tomography is used to visualize and measure the flow behind the meniscus in CD-flows of water and blood. Microchannels of polydimethylsiloxane and glass with different cross-sections are considered. The predictions of the flow behind the meniscus of numerical simulations using the power-law model for non-Newtonian fluids are in reasonable agreement with the measurements using blood as working fluid. The extension of the Lucas-Washburn equation to non-Newtonian power-law fluids predicts well the velocity of the meniscus of the experiments using blood.</P>
Numerical and experimental modelization of the two-phase mixing in a small scale stirred vessel
Sylvana Varela,Manuel Martínez,Jorge A. Delgado,Cyril Godard,Daniel Curulla-Ferré,Jordi Pallares,Anton Vernet 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.60 No.-
The numerical prediction of mass transfer rates of gas components within the liquid phase in a stirred two-phase flow reactor is presented. Experiments have been conducted to determine the flow regime and the number and sizes of the bubbles formed under different conditions. The dynamic field of the two-phase flow was obtained through numerical simulations. Bubbles with the experimentally measured diameter were released from the free surface and tracked numerically to compute the particle Reynolds number, which is used to determine the mass transfer rates. The unbaffled reactor provides mass transfer rates 30% larger than the baffled reactor for the bubbly flow. Mass transfer rates drop about 65% when the emulsion is formed. Therefore, above the critical rotation rate at which the emulsion forms for the unbaffled reactor, the baffled configuration provides larger mass transfer rates. The results indicate that even for the most unfavorable case mass transfer is not the limiting step, as 90% of the equilibrium concentration is reached in 10 s.