Molecular-Scale Solutal Electrokinetics and Micro-Scale Control of Interfacial Phenomena in Ebullient Heat Transfer

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CBET-0755720, ManglikThis research is a fundamental multi-scale study of the molecular electrokinetics of surface-active agents (organic/synthetic monomers, micelles and/or biomolecules), and their modulation of interfacial phenomena (surface wetting and interfacial tension) for the control of nucleate boiling and associated ebullience in aqueous solutions. At the molecular-scale, the additive molecular dynamics at the liquid-vapor interface, and its physisorption and electrokinetics at the liquid-solid interface are to be investigated. These processes in turn affect micro-scale changes in liquid-vapor interfacial tension and solid-liquid wetting (where the two usually complimentary forces can now be decoupled due to the reagent electrokinetics and molecular mobility). The consequent changes in transient transport mechanisms during pool boiling with its characteristic embryonic vapor nucleation and subsequent bubble growth will be investigated. Also, the macro-scale ebullient heat transport, governed by macro-layer interfacial heat transfer, bubble growth and its dynamics (coalescence, collapse, and translation) will be studied and modeled, so as to identify and correlate boiling control (enhancement or suppression) parameters. In essence, the principal hypothesis that liquid-vapor interfacial tension and solid-liquid surface wetting (primary determinants of micro-scale nucleation and macro-scale ebullience, and hence boiling control predictors) can be decoupled and controlled by the molecular adsorption-physisorption, micellar dynamics, and electrokinetics of reagents in aqueous solutions would be established, and predictive correlations developed. Intellectual Merit: The findings of this study will (i) advance the fundamental science of interfacial phenomena and its manipulation by the molecular dynamics of surface-active agents in aqueous solutions, (ii) be insightful in establishing the micro-scale mechanisms at liquid-solid and liquid-vapor interfaces that characterize nucleate phase-change, and (iii) lead to the advancement of the fundamental science and engineering for an effective passive control technique, using ?designed? reagents (nano-sized micelle-chains and surfactant-like protein-based biomolecules), for nucleate phase-change ebullience and heat transfer. Broader Impact: This project will significantly enhance the training of students in cross-stream and inter-disciplinary engineering science, provide an experience in advanced experimentation (state-of-the-art instrumentation) and mathematical/simulation analysis, and help produce highly motivated engineers and researchers who have the depth and breadth of knowledge, and skills for advanced research and education careers. The integration of research with education, particularly involving women and minority engineering students, would further address the national need of training a more diverse engineering work force. Also, outreach with industrial and national laboratory partners will lend to long-term technology transfer. In a broader transformative essence, the reagent molecular dynamics/electrokinetics-modulated ebullient phase-change discovered in this work, is a new frontier in developing not only novel chemical and biological sensors, micro-fluidic or lab-on-chip devices, micro-scale heat exchangers, and effective thermal management of space-based systems, but also novel surface-active biomolecules and micellar polymers that may have a wider range of inter-disciplinary applications.