Dispersion behavior of surfactant-free W/C emulsion in high reynolds number turbulent flow fields

Our group has developed a new powder manufacturing process that employs the spray-drying of emulsion consisting of nanoparticle-dispersed aqueous solutions and carbon dioxide. The method has high productivity and controllability of powder size by using high Re number turbulent field and the Joule-Thomson effect caused by the adiabatic expansion of CO₂. However, the dispersion state of the emulsion in high Re number turbulent flow field and the effect of aggregation in the spray process are unclear. In this study, a visualization cell was developed, and the C/W emulsion was observed by using high speed camera in a high Re number turbulent field. It was confirmed that the emulsion drops do not aggregate in the high Re number turbulent field even though no surfactant was used. Moreover, it was suggested that the fine particles contained in the emulsion were preserved intact in the dried powder particles.