Gas flow rate measurement in two-phase flows using an optical channel body flow sensor. Design and validation of the single-channel prototype

Accurate measurement of gas holdup and flow rates in gas-liquid two-phase flows remains a complex and unresolved challenge. This paper presents the development and evaluation of an Optical Channel Body Flow Sensor (OCBFS) designed for the simultaneous measurement of volumetric gas and liquid flow rates. The measurement principle is based on formation of slug flow regime in small capillaries, where liquid and gas phase are separated. The sensor utilizes a plastic optical fiber-based sensing principle. Experimental validation of the OCBFS was conducted for a single channel across a range of superficial velocities, with liquid velocities between v l,s = 0.14–0.31 m/s and gas velocities between v g,s = 0.015–0.95 m/s, resulting in the formation of slug flow in a capillary with a diameter D c = 2.5 mm. The slug flow results showed deviations of less than 10 % from reference values, confirming the sensor's accuracy and reliability in gas flow measurements under adiabatic conditions. The OCBFS prototype provides a solid foundation for precise flow measurement in two-phase systems, advancing gas-liquid flow measurement technologies for applications that require reliable flow rate monitoring. • Development and validation of an Optical Channel Body Flow Sensor (OCBFS) for two-phase flow measurement. • The OCBFS employs a plastic optical fiber-based sensing principle to measure gas and liquid flow rates simultaneously. • Experimental testing across a wide range of superficial velocities ( v l,s = 0.14–0.31 m/s and v g,s = 0.015–0.95 m/s). • Results demonstrated a measurement accuracy with deviations of less than 10 % from reference values. • The OCBFS shows significant potential for precise flow monitoring in complex gas-liquid two-phase systems.