Numerical analysis on droplet mixing induced by microwave heating: Decoupling of influencing physical properties. (12th October 2020)

• Record Type: Journal Article
• Authors: Cui, Weijia; Yesiloz, Gurkan; Ren, Carolyn L.
• Is Part Of: Chemical engineering science. Volume 224(2020)
• Publication Date: 2020-10-12
• Subjects: Droplet microfluidics -- Rapid mixing -- Microwave heating -- Interfacial tension -- Marangoni flow; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2020.115791
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: Mechanism of microwave heating induced mixing in droplets is revealed numerically. Interfacial tension plays a key role in microwave heating induced droplet mixing. The revealed mechanism contributes on exploiting microwave heating for rapid mixing. Abstract: Microwave resonator offers simultaneous sensing and heating of individual droplets in microchannels presenting unique advantages for applications requiring well-controlled reaction time. This study numerically investigates the effects of the temperature-dependent fluid properties including viscosity, density, diffusivity, and interfacial tension, on microwave heating induced mixing. A system consisting of a spiral resonator integrated with a microchannel with aqueous droplets moving with a carrier oil is considered. The electromagnetic field which provides heating to the droplets, and the flow and tracer concentration fields inside the droplet are obtained using commercial software, Ansys HFSS and Fluent, respectively. It is found that the mixing index can be increased from 0.4 to 0.84 within 320[ms] with microwave heating and it would be slightly increased to 0.47 when only the interfacial tension was made independent on temperature, which suggests that the temperature-dependent interfacial tension is the dominant factor for microwave heating induced mixing.