Measurement of oil bubble size distribution in oil-in-water emulsions using a distributed dual-sensor probe array

The scope of the present study is to experimentally investigate the oil bubble size distribution in oil-in-water emulsions. The geometry parameter of a dual-sensor probe is firstly optimized through examining its electrical field distribution and sensitivity. Afterward, an eight-channel distributed dual-sensor probe array is designed for a pipe with 20 mm inner diameter (ID) to measure the local holdup, bubble velocity as well as bubble size of the dispersed oil phase in oil-in-water emulsions under low mixture velocity and high water-cut. The results indicate that the changes in mixture velocity and water-cut substantially affect the oil bubble size distribution on different positions at the pipe cross section. With the extraction of the increasing rate regarding multi-scale cross entropy (MSCE) from the fluctuating signals from the leading and rear sensor of the dual-sensor probe, the dynamic instability in the motion of oil bubbles is analyzed. It proves that the multi-scale cross entropy can be an effective indicator on globally characterizing the nonlinear dynamics in oil-in-water emulsions at the pipe cross section.