"Optofluidics for Carbon Management and High Inertial Droplet Flows" by Dr. Myeongsub 'Mike' Kim (Mechanical Engineering Department at the University of Texas at Austin)
Abstract: Microfluidics techniques have offered various advantages over conventional methods such as reduced cost, time and sample volume, fast diffusion and reaction, and efficient system integration due to the scale-down of the feature size or volume. Combining with optical diagnostics, termed as optofluidics, microfluidics has recently been leveraged to numerous applications. In this talk, I will explore two specific examples of optofluidics techniques in energy and biological applications: 1) CO2 management for climate control and 2) high inertial droplet formation and collision mixing. In the first part of this talk, I will describe optofluidics approaches to tackle two major issues occurring during CO2 injection to geological saline aquifers including CO2 diffusivity to the resident fluid and solid precipitations in the aquifer formation. Optofluidics techniques helped to measure mutual diffusion coefficients of carbon dioxide in water and brine with a significantly reduced sample volume at a shorter timescale. Results showed a good agreement with the conventional pressure-volume-temperature method, suggesting an excellent applicability of optofluidics techniques to diffusivity measurements of various substances. Using optofluidics, I could also, for the first time, visualize clear mechanisms of solid precipitations at pore scale during CO2 injection when three phase (CO2-saline-solid) flows got involved. Two dominant types of solid formations were observed: large crystal structures at earlier time in the liquid phase and polycrystalline structures at later time in the CO2 phase. Implication of these results will be discussed. In the second part of the talk, I will introduce an optofluidics technique that generates gas-liquid micro-droplets at Reynolds numbers Re=70−370 enhancing throughput and mixing efficiency. Droplets in a gas environment are particularly of interests in spray cooling technology and biological applications because post-processing such as oil filteration and separation is not typically required. I will discuss characterization of high inertial gas-liquid droplet microflows in terms of generation frequency, droplet size, and flow regimes. Finally, I will present a recent study of droplets collision mixing under high inertial flow conditions.
Bio: Myeongsub “Mike” Kim is a postdoctoral fellow in the Mechanical Engineering Department at the University of Texas at Austin with Dr. Carlos Hidrovo. He received his Ph.D. from the Georgia Institute of Technology in 2011 with Dr. Minami Yoda on development of nonintrusive measurement techniques for fluid and wall surface temperatures at microscale using fluorescence thermometry. He was a postdoctoral fellow at the University of Toronto, Canada, from 2011 to 2012, where he worked with Dr. David Sinton. His research interests include optofluidics, thermal-energy systems, thermal management, diagnostic techniques related to thermal-fluid sciences, oil and gas, and biological and energy applications.