Capacitance Probes for Measurement of Liquid Film Thickness

Liquid film thickness measurement is very important in multiphase science and technology. A capacitance probe is presented in this paper, including its basic principle, geometrical design, electronic circuit, and experimental tests in measuring film thickness during gas-liquid two-phase flow. This method is based on the difference between the dielectric constants of the gas and liquid phases. A ratio-arm bridge circuit is used to convert the capacitance of the fluids between twin parallel plates into voltage. The voltage output from the capacitance probe exhibits an excellent linear relationship with the liquid film thickness. Experiments have shown that the parallel-probe capacitance method is very suitable to gas-hydrocarbon liquid system.