Search results for "BUBBLES"
showing 6 items of 46 documents
ON THE BUBBLING DYNAMICS OF BINARY MIXTURES OF PARTICLES IN 2D GAS-SOLID FLUIDIZED BEDS
2011
The bubbling behaviour of fluidized beds has been thoroughly investigated in the last decades by means of several techniques, e.g. X-ray, Inductance, Resistance and Impedance based techniques, PIV. In recent years, Digital Image Analysis Techniques have shown their potential for accurate and cost effectively measurements. Most of the work related to bubble behaviour analysis deals with monodispersed particles, while almost all industrial equipment operates with mixtures of particles. Although considerable work has been done in the past with focus on the analysis of the mixing-segregation behaviour and predictions of fluid dynamics regime transitions, a lack of knowledge exists in the analys…
On the measurement of local gas hold-up, interfacial area and bubble size distribution in gas–liquid contactors via light sheet and image analysis: I…
2013
Abstract In this work a novel experimental technique for measuring local gas hold-up, interfacial area and bubble size distribution, in gas–liquid systems is proposed. The technique is based on advanced Image Processing coupled with experimental set-ups typically available for Particle Image Velocimetry. A fluorescent dye dissolved in the liquid phase allows to identify in-plane bubbles among all visible bubbles in the images. To this end, a suitable algorithm is proposed. The raw data so obtained are processed by previously developed statistical methods that result in a reliable reconstruction of actual dispersion properties. The technique is applied to the case of a gas-dispersed mechanic…
On the bubbling dynamics of binary mixtures of powders in 2D gas-solid fluidized beds
2012
Abstract The bubbling behavior of fluidized beds has been thoroughly investigated in the last decades by means of several techniques (e.g. X-ray, Inductance, Resistance and Impedance based techniques). In recent years, Digital Image Analysis Techniques have shown their potential for accurate and cost effective measurements. Most of the works related to the experimental analysis of bubble behavior in the field of gas-solid fluidization actually deal with monodispersed particles although almost all industrial equipments operate with mixtures of particles. Among the works available in literature dealing with mixtures of particles having different diameters and/or densities, most of them aim at…
Modelling and simulation of gas-liquid hydrodynamics in mechnically stirred tanks
2007
Abstract Computational fuid dynamics (CFD) is an increasingly important tool for carrying out realistic simulations of process equipment. In the case of multiphase systems the development of CFD models is less advanced than for single-phase systems. In the present work CFD simulations of gas–liquid stirred tanks are reported. An Eulerian–Eulerian multi-fluid approach is used in conjunction with the simplest two-phase extension of the k–ɛ turbulence model. All bubbles are assumed to share the same size. The effect of inter-phase forces on simulation results is separately considered. As concerns drag, it is shown that the sole parameter needed to characterize the dispersed phase behaviour is …
New frontiers in liver ultrasound: From mono to multi parametricity
2021
Modern liver ultrasonography (US) has become a "one-stop shop " able to provide not only anatomic and morphologic but also functional information about vascularity, stiffness and other various liver tissue properties. Modern US techniques allow a quantitative assessment of various liver diseases. US scanning is no more limited to the visualized plane, but three-dimensional, volumetric acquisition and consequent post-processing are also possible. Further, US scan can be consistently merged and visualized in real time with Computed Tomography and Magnetic Resonance Imaging examinations. Effective and safe microbubble-based contrast agents allow a real time, dynamic study of contrast kinetic f…