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Heat and mass transfer behaviour of condensed water on nanostructured surfaces

Dr. Ryan Enright

Bell Labs, Ireland

In the last two decades, substantial efforts have been focused on understanding how surface micro- and nanostructuring can modify the behaviour of wetting liquids to produce interesting and, potentially, very useful effects. One well known example is the “Lotus-effect”, whereby the combination of intrinsic hydrophobicity and surface structuring results in superhydrophobic droplet behaviour characterized by contact angles approaching 180° and negligible contact angle hysteresis. Developing fundamental understanding of these interactions and realizing suitable material systems for thermal applications is a key challenge to unlocking further performance enhancements and new functionalities in the area of phase-change heat and mass transfer. Indeed, while rapidly developing, the area of surface-enhanced phase-change remains full of surprises and opportunities.

In this talk, I will present an overview of phenomena we have been investigating on engineered surfaces that have the potential to make great gains in application areas including thermal management, water desalination, energy efficiency and energy harvesting. Specifically, our recent work has focused on understanding the role of surface structuring in controlling the heat and mass transfer performance of dropwise water condensation. Using a combination of material synthesis, experiment, analysis and simulation, we have developed important physical insights into this heterogeneous phase-change process. This talk covers the fundamental surface structuring requirements to achieve different types of droplet wetting morphologies, the role of droplet wetting morphologies on individual droplet heat transfer, the underlying mechanism of jumping droplets and its impact on overall heat transfer performance, experimental heat transfer results and the phenomenon of condensed water droplet charging that promises a new approach to control condensed water transport and harvest energy from waste heat.

Dr. Ryan Enright earned his B. Eng. (Hons) and PhD. degrees in Mechanical Engineering from the University of Limerick in 2004 and 2008, respectively. He was a Research Assistant at Bell Labs in Murray Hill, New Jersey from 2005-2007 during his doctoral work. After receiving his PhD., he was a CTVR postdoctoral associate at the University of Limerick from 2008-2009 and a postdoctoral fellow at the Massachusetts Institute of Technology from 2009-2012. He joined Bell Labs Ireland in 2012 where he is currently the technical lead for the Thermally Integrated Photonics Systems (TIPS) program and a Research-in-Residence at the CRANN Institute, Trinity College Dublin. Ryan conducts experimental and theoretical research in the area of micro/nanoscale heat and mass transfer and has a strong interest in applied surface science. Ryan has coauthored more than 25 journal contributions and currently holds two granted patents with twelve patents pending. Ryan’s research has been honoured with awards including a SFI-funded PhD. fellowship, a 2009 IRCSET Inspire/Marie Curie Mobility Fellowship, two SFI-funded National Access Program awards, and best paper awards at the 2012 ASME International Micro/Nanoscale Heat and Mass Transfer Conference and the 2014 IEEE ITherm Conference.