Integration of impedance measurements with transit time measurements for ultrasonic gas mass flow metering-model and experiments with transducers in different vibration modes

Abstract

Previous studies have yielded promising results as to the use of impedance measurements on wetted ultrasonic transducers in gas in estimating the density of gas. Earlier results were analysed using simple models and compared with chemometric analysis. This paper presents a new series of impedance measurements with more details of the models based on selected vibration modes using different transducers in selected gases and gaseous mixtures. The measurements were done using controlled environments of pressure and temperature. The impedance measurements are used to estimate the density of the gases or gaseous mixtures. A comparison of the impedance based density measurements and simulations is also presented. The paper looks also into some error bound analysis for both methods. With the intelligence in sensors and systems increasing, these measurements show that by incorporating the impedance measurements and the associated algorithms on a system on chip, the present day ultrasonic volumetric flow meters can in fact become competitive mass flow meters. The paper finishes addressing these issues.