Capacitive Multielectrode Direct-Imaging Sensor for the Visualization of Two-Phase Flows

摘要

In this paper, a novel capacitive array-sensor to visualize two-phase flow by measuring liquid holdup in pipe cross-section is introduced. The measuring principle is based on the difference between electrical permittivity of the phases. The sensor consists of two copper rings being an emitter and one receiver ring. The receiver ring is divided into segments, which are individually interrogated by the measuring electronics in a fast manner. In this way, flow images are directly generated from acquired signals of electrodes in a way that it visually represents the investigated flow, avoiding the use of image reconstruction algorithms as usual in tomographic techniques. The sensor is fabricated in a flexible printed-circuit board, which is flush-mounted in the inner pipe wall. A measuring electronics is responsible to detect the capacitance changes in the electrodes. The introduced sensor along with the associated electronics has been tested in static and dynamic two-phase flow, both horizontally and vertically. Direct images were generated in these different situations, showing satisfactory results when compared with a reference wire-mesh sensor.