Experimental study on millimeter-scale W1/O/W2 compound droplets formation in a co-flowing device with two-step structure. (28th April 2020)

• Record Type: Journal Article
• Authors: Pan, Dawei; Chen, Qiang; Chen, Shufan; Li, Bo
• Is Part Of: Chemical engineering science. Volume 216(2020)
• Publication Date: 2020-04-28
• Subjects: W1/O/W2 compound droplets -- Co-flowing microfluidic device -- Two-step structure -- Flow mechanisms; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2020.115493
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: Monodisperse W1/O/W2 compound droplets with millimeter-scale are stably prepared. The formation process of compound droplets is quantitatively studied. The size variation of the compound droplets are extensively investigated. A prediction correlation for dimensionless outer diameter is established. Abstract: W1/O/W2 compound droplets generation in a co-flowing microfluidic device with two-step structure was observed through experiments, and the formation process is quantitatively studied. Further the effects of the flow rates of all phases as well as the viscosity of W2 phase on the geometric size are extensively investigated. The results indicate that the outer diameter of compound droplets mainly depends on the flow rate and viscosity of external phase. The core water droplet diameter can be controlled by adjusting the flow rates of both inner and middle phases, and it is more sensitive to inner phase. Generally, the inner diameter of compound droplets is not only relative to the core droplet diameter, but also influenced by the encapsulated core water droplet number. Finally, a prediction correlation for dimensionless outer diameter with several dimensionless numbers is obtained. The results could provide an experimental basis for controllably preparing millimeter-scale monodisperse compound droplets.