Digital Image Analysis Technique for mixing pattern measurements in bi-dispersed 2D gas fluidized beds

This work concerns a new experimental technique based on Digital Image Analysis aimed at the measurement of the mixing behaviour of the granular phase in a 2D fluidized bed. In particular, the preliminary results obtained about the mixing pattern of a bi-disperse 2D gas fluidized bed are reported. Two different kind of particles were fluidized having the same density but different size. The technique is based on suitable colour-field decomposition of the fluidized bed, in which particles of different colours are employed. The technique here proposed can effectively measure the concentration field in the whole bed during operation, thus obtaining data that can be reliably used for CFD simula…

CFD prediction of bubbles local gas hold-up in 2-dimensional gas-solid fluidized beds

Analysis of bubbling fluidization dynamics

Experimental Analysis of bubbling dynamics in bidisperse gas-solid 2D fluidized beds

Lagrangian simulation of bubbling dynamics in a lab-scale 2D fluidized bed

The present work focuses on the development of a novel computational code able to predict with a reasonable level of accuracy the bubble behavior in gas fluidized beds with minimum computational demands. The code simulates the bubble chaotic rise motion and coalescence along bed height via simple lagrangian tracking of bubbles. An original empirical model for the assessment of bubble-bubble interactions is developed. The code is used to simulate a lab-scale unit in bubbling and slugging mode. On this basis, fast simulations are performed to successfully predict bubble population and fluxes within the bed. The main aim of this code is to be embedded within CAPE codes for the process simulati…

A Digital Image Analysis Technique for 2-D Gas-Solid Fluidized Beds

Misura di proprietà ottiche di fotocatalizzatori

Analysis of the bubbling behaviour of 2-D gas solid fluidized beds part II: Comparison between experiments and numerical simulations via Digital Image Analysis Technique

In the field of gas–solid fluidization, bubbles, and all features regarding them, have a very great importance, as they significantly affect the process performance. Numerous experimental studies on bubbles, and their formation, evolution, and properties, have been performed in the past. These investigations appear particularly difficult, due to the nature of these systems, since the gas phase is distributed in both the bubble and the emulsion phase. Several experimental approaches have been developed to tackle this study. Among these, the Digital Image Analysis Technique purposely developed in Part I of the present work, based on the use of a video camera for monitoring the phenomenon coup…

CFD PREDICTION OF BUBBLES BEHAVIOUR IN 2-DIMENSIONAL GAS-SOLID FLUIDIZED BEDS

In recent years the use of Computational Fluid Dynamics (CFD) is significantly increasing to simulate multi-phase flows. It is invariably emphasized that a necessary step towards the development of reliable fully predictive CFD models is an extensive experimental validation of the simulation results. This work in particular focuses on the CFD simulation of a lab-scale 2D fluidized bed and the relevant experiments, in order to validate the prediction capability of the used codes and models. It must be emphasized that both experimental and computational quantitative data have been obtained by means of an original Digital Image Analysis Technique, that allows coherent comparison of computation…

Investigation of fluidization dynamics at various flow regimes

The Six Flux Model for the modelling of radiant fields in heterogeneous photoreactors

Experimental investigation of fluidization dynamics at various flow regimes

CFD simulations of spacer-filled channels for pressure retarded osmosis applications

Different spacer features and operating conditions were investigated in order to identify a good compromise between concentration polarization and pumping power reductions.

Studio di cinetiche di reazione in un reattore fotocatalitico quasi-isoattinico

Numerical simulations of bubbling fluidized beds

Lagrangian simulation of bubbling behaviour in gas fluidized beds and validation with experimental data

Study of bubbling fluidization dynamics via Digital Image Analysis Technique

A Six Flux Model for the estimation of radiant fields in flat heterogeneous photoreactors

Misure di proprietà ottiche di fotocatalizzatori

Study of bubble size distribution in bubbling fluidized beds via Digital Image Analysis Technique

Pressure Retarded Osmosis: a Membrane Process for Environmental Sustainability

Salinity Gradient Power (SGP) based on the controlled mixing between two solutions at different salinities is a viable alternative to produce power from renewable sources. Pressure Retarded Osmosis (PRO) is one of the most promising technologies proposed so far for the exploitation of such energy source. Apart from the typical source of salinity gradients, namely river water and seawater, more and more interest has been raised recently towards the use of non-conventional saline solutions. In this work, water originating from a sewage treatment plant is used as the dilute solution (feed solution), while brine exiting from a desalination plant is used as the concentrate (draw solution), thus …

Analysis of the bubbling behaviour of 2-D gas solid fluidized beds - Part I Digital Image Analysis Technique

Bubble characteristics are very important in the design of fluidized beds because they govern hydrodynamics and efficiency of the operation for which the bed is used. In this work, a digital image analysis technique has been developed to study the fluidization dynamics of a lab-scale two-dimensional bubbling bed. Digital image analysis may supply a great quantity of information; it is non-intrusive, capable of securing several properties simultaneously and cost effective. The image analysis method here developed allows for the simultaneous measurements of various significant bubble properties, i.e. bubble size and bubble velocity distributions, bed height and bubble-phase hold-up, by means …

Mathematical Model and Stability analysis of Multiphase Flow in Fluidized Beds