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.