Identification of the Catastrophic Phase Inversion Point of Water-in-Oil Emulsion Using Ultrasonic Measurements

Ultrasonic spectroscopy to characterize fluids has recently gained popularity as a nonintrusive and noninvasive technique. Recent studies have addressed the performance of sensors in characterizing dilute emulsions. However, it is challenging to interpret the acoustic properties of the very concentrated emulsions close to the phase inversion region. Thus, a study that explores the analysis of these properties in these samples is interesting to understand better whether the ultrasonic technique can be helpful in the characterization of these emulsions. This work aims to study the application of acoustic measurements to identify the catastrophic phase inversion point during emulsion flow in a closed-loop circuit flow. The main acoustic variables, such as sound velocity, reflection coefficient, and acoustic attenuation, were monitored to obtain an in-depth interpretation of this process. For this purpose, five experimental points of phase inversion were planned. The surfactants for each point had a different affinity with the oil (different hydrophilic–lipophilic balance, HLB). The analysis was conducted at two temperature points, with the acoustic variables monitored for each experimental point. It was possible to conclude that the acoustic variables, such as reflection and attenuation coefficients, had abrupt changes during phase inversion. These variables can be used to determine the phase inversion point and qualitatively characterize the morphology of the emulsion during the process.