题目：Nanostructured Materials and Nanoscale Effects for Advanced Heat Transfer
Sheng Shen is currently Associate Professor at the Mechanical Engineering Department of Carnegie Mellon University (CMU). He received his PhD degree from the Mechanical Engineering Department, MIT, with Prof. Gang Chen in 2010. He had his bachelor and master degree from the Power Engineering Department, Huazhong University of Science and Technology, China, in 2000 and 2003, respectively. Prior to joining CMU in 2011, he conducted his postdoctoral research with Professor Xiang Zhang at UC-Berkeley. His research interests include nanoscale heat transfer and energy conversion, nanophotonics, and their applications in solar or thermal energy conversion, thermal management, and multifunctional materials. Professor Shen is a recipient of NSF CAREER Award, DARPA Director's Fellowship, DARPA Young Faculty Award, and Elsevier/JQSRT Raymond Viskanta Award for Spectroscopy and Radiative Transfer. He also received the CMU Dean's Early Career Fellowship, the Philomathia Foundation Research Fellowship in Alternative Energy Research from UC-Berkeley, a Hewlett-Packard Best Paper Award from ASME Heat Transfer Division, and a Best Paper Award in Julius Springer Forum on Applied Physics.
In this talk, he will give three examples about utilizing nanostructured materials and nanoscale effects to develop advanced thermal transport technologies. First, he will discuss novel thermal interface materials (TIMs) for electronics cooling, based on compliant and thermally conductive nanostructures. In contrast to conventional TIMs such as solders and epoxies, large-scale ordered nanostructures, e.g., metal nanowires, can increase mechanical compliance of TIMs but maintain high thermal conductivity, thus enhancing the performance and reliability of TIMs. Second, I will report a new fabrication method that can consistently produce polyethylene (PE) nanofibers with diameters ranging from 10 to 100 nm. We demonstrate unique phonon transport in the nanofibers by measuring their thermal conductivity in a broad temperature range from 20 to 320 K. Strength measurements show ultra-high tensile strength, 11.4 ± 1.1 GPa, for our crystalline PE nanofibers. To the best of our knowledge, this is the highest strength measured for any polymer based fibers, such as aramid fibers (Kevlar), carbon fibers and composite fibers. Finally, he will experimentally demonstrate that near-field thermal radiation can exceed Planck’s blackbody radiation by three orders of magnitude at nanoscale gaps. He will also show broad near-field thermal radiation control by metals, semiconductors and metamaterials.