A Liquid Film Thickness Measurement Scheme Using a Multielectrode Conductivity Compensation Method

Accurate measurement of liquid film thickness (LFT) is vital in industrial processes involving multiphase flow. Existing conductivity probe methods face challenges when the electrical conductivity of the liquid fluctuates due to temperature changes and varying parameters. The present work proposes a coplanar five-electrode conductivity probe for a reliable measurement of dynamic LFT. This new design features a shared source electrode along with two sets of measuring electrodes on each side, operating as two separate sensors, which can save a significant area when used as an array. The electrode dimensions are optimized numerically, then its response is evaluated through a static experiment. The voltage ratio obtained from each set of measuring electrodes exhibits a near-constant response for water samples with different conductivities. Thus, the proposed probe can effectively compensate for time-varying conductivity, ensuring accurate measurement of dynamic LFT. The measuring range of the sensor is found to be 3 mm. There is a reasonable match between the results obtained experimentally and numerically. Its simplicity, reliability, reproducibility, and low cost make it suitable for industrial applications operating in harsh environments.