Real-time measurement of particle volume fraction in centrifugal fields by wireless electrical resistance detector

Abstract

A wireless electrical resistance detector (WERD) has been developed to measure the real-time particle volume fraction in centrifugal fields. The developed WERD is composed of an AC (alternating current) generation device, a measurement circuit and a wireless transmission module. The effective sensing area of measurement electrodes of WERD was clarified by the three dimensional electrostatic field simulations. In order to evaluate the measurement accuracy, the developed WERD is attached around a lab-scale centrifuge, and the real-time volume fraction of polymer pellets in the centrifugal field is measured at various positions zm under various rotational velocity ω and initial particle loading height hp. The measured particle volume fraction αp at various measurement positions indicates a parabolic separation interface between the particle phase and the sodium chloride solution phase, which are in good agreement with the numerical simulation by Euler-Euler method for validation with an average deviation of 2.47%. As the rotational velocity ω is increased, particles are pushed outward to be raised along the cylindrical vessel because of the increased centrifugal force, which causes sharper paraboloid interface. Moreover, as the initial particle loading height hp is increased, the parabolic phase interface shifts upward while the parabolic surface profiles of the phase boundary almost keep constant for the same rotational velocity ω.