Dr. Akshay Kundan's Talk

Sep 06, 2018 - 17:00

Sep 06, 2018 - 18:00

Room 118 Chemical Engg Dept

Seminars

Dr. Akshay Kundan Momentive Performance Materials Inc. USA

Abstract: Heat pipes are critical components in cooling of systems present in space. The Constrained Vapor Bubble (CVB) is a transparent wickless heat pipe system tested on the International Space Station (ISS) where the Bond number (ratio of gravitational force to surface force) is small maximizing the effects of capillarity. The CVB is made up of square fused silica spectrophotometer cuvette which is then partially filled with pentane or a mixture of pentane and isohexane (94% pentane 6% isohexane) as the working fluid. Along with the temperature and pressure measurements the image data obtained from the experiment using the interferometry based system contained with the station’s Light Microscopy Module (LMM) can be used to determine the spatial details of the curvature of the liquid vapor interface. The image obtained from the transparent system of CVB was ideally suited to determining if Marangoni forces might contribute to limiting heat pipe performance and exactly how that limitation occurs. A unique way to determine the internal radiative exchange was developed. Internal radiative exchange was found to be more significant than originally anticipated. An analysis of the temperature profiles in conjunction with vapor-liquid interface mapping showed that the system could be separated into a number of discrete operation zones depending on the dominant mode of heat transfer. The first limitation is found to be totally opposite to that predicted in the literature. We observe a flooding limitation instead of the predicted dryout limitation from the literature. None of the present mathematical models in its current form can predict this limitation. Moreover the growth of this region is arrested in 40 mm CVB modules because of the balance of opposite flows. An additional phenomena is observed in 40 mm modules which looks like a microjet inside a heat pipe. Interferometry technique is used to determine the fluid physics of the microjet. The CVB experiment in microgravity environment of the International Space Station has provided us with a good understanding in the performance limitation of a heat pipe. Extensive 3D models can be developed to validate the findings of the CVB and can be used to design a better heat pipe. The heat pipes developed validating the data from the CVB experiment can be a big step towards a long term manned mission in space.Bio: Akshay Kundan was born and brought up in and around Nagpur area a city located in the central part of India. After completing his high school studies from Bharitya Vidya Bhawan in Nagpur he obtained his Bachelors of Technology (B.Tech) degree in the Department of Chemical Engineering from Indian Institute of Technology – Banaras Hindu University Varanasi. Later he went on to attend Rensselaer Polytechnic Institute (RPI) in New York (USA) for his doctoral studies in the Department of Chemical and Biological Engineering. He pursued his Ph.D. in the field of interfacial heat and mass transfer under the guidance of Professor Joel L. Plawsky and Professor Peter C. Wayner Jr. Akshay studied the role of interfacial forces in the performance of a heat pipe in space applications. His experiments were run in the US labs of the International Space Station. His compelling results were published and presented in various peer-reviewed journals and international conferences. Currently he has 27 publications including 10 journal publications and 17 conference publications. His publication in the Physical Review Letters in 2015 was published as a featured research in APS Physics Science and Nature journals. During his doctoral studies he received numerous prestigious awards like the William N Gill Prize (2017) for Excellence in Dissertation Research the Class of 1921 Groll Teaching Assistant Award (2016) and the Rensselaer’s Founders Award of Excellence (2015). Akshay considers receiving the Compelling Results Award from NASA in the International Space Station R&D Conference 2015 as the most significant achievement of his career so far. This award was presented by Cady Coleman a veteran astronaut with over 180 days of space experience which made it a remarkable experience. After his doctoral studies he is currently pursuing the role of Process Development Engineer in Momentive Performance Materials Inc. the second largest producer of silanes and siloxanes in the United States. His role is to scale-up technologies for new products from lab-scale to pilot scale and ultimately to the full production scale. He is also involved in improving current processes and carrying the root-cause analysis for the failures of the current technology. At Momentive he has been directly involved in the decision making process of technologies worth more than $30 million. This seminar is compulsory for students registered for course CL 702 or CL 704.