Imaging Particulate Two-Phase Flow in Liquid Suspensions with Electric Impedance Tomography

Abstract

Different approaches have been followed to model the hydraulic transport of particles, ranging from pure empirical correlations to general models based on fundamental principles. However, these models suffer from uncertainties associated with the parameters in the constitutive equations and scarcity of experimental data in the literature. Nonintrusive techniques such as electric impedance tomography (EIT) can be used to circumvent the difficulties associated with sampling techniques. EIT is an imaging technique for the phase distribution in a two-phase flow field, allowing reconstructing the resistivity/conductivity distribution gradients from electrical data in a medium subjected to arbitrary excitations. Our best efforts were concentrated on the development of a new EIT system that is analogue based, portable, low-cost, and capable of providing high-quality sharp images when used to characterize the flow of particle suspensions. A voltage source was used, rather than a more complex and costly current source, since it provided the EIT system with a more precise and flexible current output. The data acquisition system consists of 16 electrodes equally spaced in the boundary of a tube and a custom dedicated electronic apparatus. The software supplies results in the form of two-dimensional reconstructed images that allow mapping the phase distribution inside the tube.

Keywords:

• electrical impedance tomography
• finite element method
• tomographic system
• two-phase flow
• voltage source

Acknowledgments

This work has been financially supported by the Fundação para a Ciência e Tecnologia, project PTDC/EQU-EQU/66670/2006. The University of Delft kindly donated the test tube sections with the rings of electrodes, developed in the laboratory of the late Professor Brian Scarlett.