Evaluation of EIT Systems and Algorithms for Handling Full Void Fraction Range in Two-phase Flow Measurement

Abstract

This is an author-created, un-copyedited version of an article accepted for publication in Measurement Science and Technology. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/0957-0233/26/1/015305.In the aqueous-based two-phase flow, if the void fraction of dispersed phase exceeds 0.25, the conventional Electrical Impedance Tomography (EIT) produces a considerable error due to the linear approximation of Sensitivity Back-projection method, which limits the EIT’s wider application in process industry. In this paper, an EIT sensing system which is able to handle full void fraction range in two-phase flow is reported. This EIT system employs a voltage source, conducts true mutual impedance measurement and reconstructs online image with the Modified Sensitivity Back-Projection (MSBP) algorithm. The capability of Maxwell relationship to convey full void fraction is investigated. The limitation of linear sensitivity back-projection method is analysed. The modified sensitivity back-projection algorithm is used to derive relative conductivity change in the evaluation. Series of static and dynamic experiments demonstrate the mean void fraction obtained using this EIT system has a good agreement with reference void fractions over the range from 0 to 1, which would significantly extend the applications of EIT in process measurement