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Seminar 4/20/2011 - Prof. Kripa Varanasi, MIT: Nanoengineered Surfaces for Efficiency Enhancements in Energy and Water

Professor Kripa K. Varanasi
Mechanical Engineering
Lab for Nanoengineered Surfaces, Interfaces & Coatings
Massachusetts Institute of Technology

Bio:
Kripa Varanasi is a d'Arbeloff Assistant Professor of Mechanical Engineering at MIT. He received his B.Tech from IIT, Madras and his MS (ME and EECS) and Ph.D from MIT.  Prior to joining MIT, Dr. Varanasi was a lead research scientist and project leader in the Energy & Propulsion and Nanotechnology programs at the GE Global Research Center, Niskayuna, NY, and was the PI for the DARPA Advanced Electronics Cooling program. The primary focus of his research is in the development of nano-engineered surface, interface, and coating technologies that can dramatically enhance performance in energy, water, agriculture, transportation, buildings, and electronics cooling systems. He is enabling this approach via highly interdisciplinary research focused on a nanoengineered surfaces and interfaces, thermal-fluid science and new materials discovery combined with scalable nanomanufacturing. His work spans various thermal-fluid and interfacial phenomena including phase transitions (condensation, boiling, freezing), nanoscale thermal transport, separation, wetting, catalysis, flow assurance in oil and gas, nanofabrication, and synthesis of inorganic bulk and nanoscale materials guided via computational materials design. Dr. Varanasi has filed more than 30 patents in this area. He was awarded the First Prize at the 2008 ASME Nanotechnology Symposium and won several awards at GE Research Labs including Technology Project of the Year, Best Patent Award, Inventor Award, and Leadership Award. Most recently he received the MIT Energy Initiative award, MIT-Deshpande Award, 2010 IEEE-ASME ITherm best paper award, NSF Career Award and DARPA Young Faculty Award.

Abstract:
Thermal-fluid-surface interactions are ubiquitous in multiple industries including Energy, Water, Agriculture, Transportation, Electronics Cooling, Buildings, etc. Over the years, these systems have been designed for increasingly higher efficiency using incremental engineering approaches that utilize system-level design trade-offs. These system-level approaches are, however, bound by the fundamental constraint of the nature of the thermal-fluid-surface interactions, where the largest inefficiencies occur. In this talk, we show how surface/interface morphology and chemistry can be engineered to fundamentally alter these interactions for dramatic efficiency enhancements in various energy and water systems. We study the wetting energetics and wetting hysteresis of droplets as a function of surface texture and surface energy and establish various wetting regimes and conditions for wetting transitions. We extend these concepts to dynamic wetting and establish optimal design space for droplet shedding and impact resistance. Droplet shedding plays a key role in the efficiency of steam, gas, wind turbines and aircraft engines. We then present the behavior of surfaces under phase change, such as condensation, and freezing using an environmental SEM. We find that surfaces can be engineered to promote dropwise condensation but result in a mixture of wetting states. Measurements indicate enhancement in heat transfer when compared to baseline surfaces. Further optimization of the surface by manipulating nucleation-level phenomena leads to hybrid wetting architectures similar to the one found on a Namib beetle. These hybrid surfaces show superior transport properties and have implications for high-efficiency condensation in power and desalination plants. The last portion of the talk will focus on ice and hydrate mitigation. Clathrate hydrates are an important flow assurance challenge for deep-sea oil and gas exploration and was recently a challenge in the Gulf of Mexico oil spill. Similarly, ice poses a key challenge to operational performance of wind turbines and aircraft engines. We show how interfaces can be designed to significantly reduce adhesion of both ice and hydrates. Applications of these nanoengineered surfaces to power turbines, engines, power and desalination plants, oil and gas, and electronics cooling will be highlighted.

Location: Bowen Hall Atrium

Date/Time: 04/20/11 at 12:00 pm - 04/20/11 at 1:00 pm

Category: PRISM/PCCM Seminar Series

Department: PRISM