Vietinghoff, Niclas vonLungrin, WaldemarSchulzke, RaphaelTilly, JonasAgar, David W.2020-12-112020-12-112020-12-04http://hdl.handle.net/2003/3986710.17877/DE290R-21758Applying multiphase systems in microreactors leads to an intensification of heat and mass transport. Critical aspects of the well-studied segmented slug-flow, such as bubble generation and pump control, can be automated, provided a robust sensor for the reliable determination of velocity, phase lengths, and phase ratio(s) is available. In this work, a fast and low-priced sensor is presented, based on two optical transmission sensors detecting flow characteristics noninvasively together with a microcontroller. The resulting signal is mainly due to refraction of the bubble-specific geometries as shown by a simulation of light paths. The high performance of the processing procedure, utilizing the derivative of the signal, is demonstrated for a bi- and triphasic slug flow. The error of <5% is entirely reasonable for the purpose envisaged. The sensor presented is very fast, robust, and inexpensive, thus enhancing the attractiveness of parallelized capillary reactors for industrial applications.enSensors;20(23)https://creativecommons.org/licenses/by/4.0/Segmented slug flowOptoelectric sensorOnline velocity measurementMultiphase systemsCapillary reactor660article (journal)