Measurement Methodology to Characterize Permittivity-Mass Concentration Relations of Aerated Bulk Materials

Capacitive flow meters have become widely used for flow measurements in pneumatic conveying systems. A crucial parameter for the determination of the mass flow rate is the mass concentration. Capacitive measurements are influenced by the effective permittivity of a particle-gas mixture within the sensor, which in turn depends on the mass concentration. Thus, the determination of the mass concentrations requires accurate material models, which describe the relationship between the permittivity and the mass concentration of the particle-gas mixture. In this paper we present a measurement methodology for the characterization of permittivity-mass concentration relationships for aerated bulk materials in the frequency range of 10 MHz to 100 MHz. Permittivity-mass concentration measurements for exemplary materials are demonstrated and the uncertainty of the determined material models is quantified. Hereby, relative uncertainties below 0.15% are achieved, which demonstrates the reliability of the proposed methodology.