Improving capacitance measurements of aqueous solutions with alpha and beta corrections in a parallel-plate capacitor system: Insights into dielectric properties

Abstract

Radio-frequency (RF) heating relies on a parallel-plate capacitor heating applicator system, necessitates accurate capacitance measurements despite challenges posed by fringing fields. In this paper, we present protocols for improving capacitance measurements of aqueous solutions in a parallel-plate capacitor heating applicator system operating at a frequency of 27.12 MHz. Our method incorporates alpha and beta corrections to optimize the system, ensuring accurate capacitance measurements and enabling RF heating analysis of various samples. A parallel-plate capacitor was designed to be used for dielectric characterization in terms of capacitance and impedance of water and saline under various conditions at different working temperatures. The capacitance and dielectric properties of pure water and saline solutions with varying concentrations were measured at room temperature (25 °C) using a parallel-plate capacitor and RF probe, respectively. The effects of different concentrations of air, pure water, and saline solution on the capacitance of the parallel-plate capacitor heating applicator system were also studied. Alpha and beta values were estimated from simulations to improve the accuracy and precision of the measurements. Furthermore, our RF heating analysis revealed localized overheating at the edges and corners of dry soybeans, while the remaining areas of the sample exhibited improved heating uniformity. Simulations conducted with different heat transfer coefficients highlighted the significance of RF heating in different food products using a 6 kW, 27.12 MHz RF system. Our findings offer implications for designing optimum parallel-plate capacitor heating applicator systems, applicable to fields such as food processing, medical devices, water treatment, and environmental monitoring.