Emmanuelle Fransolet

Analysis of electrical resistance tomography measurements obtained on a bubble column

Measurements of gas hold-up obtained by using pressure transducers and an optical probe are compared with those obtained by an electrical resistance tomography method. The use of a neural network, the input of which is the electrical measurements, can lead to quantitative results for the gas hold-up distribution. An interesting qualitative diagnosis of the sparger functioning is observed from reconstructed images.

Electrical resistance tomography sensor simulations: comparison with experiments

This paper compares experimental results (differences of potential), obtained with a 16-electrode electrical resistance tomography (ERT) device using the adjacent-electrode pair measurement strategy, with finite-element method (FEM) simulations in two and three dimensions. In the first part of the paper, ERT measurements made on a homogeneous medium are compared with two- and three-dimensional FEM simulations. It is shown that the dependence of the electrical field on the axial coordinate cannot be neglected. Consequently, only the three-dimensional FEM simulations are able to fit the experimental results. In the second part of the paper, ERT measurements on static physical phantoms immersed in water evidence that ERT is significantly more sensitive to non-symmetrical distributions than to symmetrical ones. This observation is confirmed by three-dimensional FEM simulations performed on numerical phantoms that mimic the physical ones. In the last part of the paper, an attempt to use three-dimensional simulations to determine the characteristics (diameter and gas content) of a gas core created by injecting a gas flow from a single-orifice gas sparger leads to promising results.

Flow Pattern Evolution With Time Mixing of Non-Newtonian Fluid in a Stirred Tank Using Particle Image Velocimetry

This paper presents an experimental analysis of the evolution with time of the flow pattern in a stirred tank equipped with a rotor-stator mixer, when mixing a time dependent non-Newtonian fluid. Particle image velocimetry (PIV) is used to determine 2D velocity maps. Polyacrylamide (PAAm) aqueous solution is used as model of time dependent shear thinning fluids. Creep compliance and recovery tests are performed to follow the evolution of the fluid rheology, from a viscoelastic behaviour to a purely viscous one. This indicates mixing has almost completely destroyed the initial network structure of the non-Newtonian fluid. The evolution of the flow pattern with the mixing time is compared with the flow patterns obtained in presence of Newtonian fluids as water and glycerol aqueous solution.Copyright