MRSEC Seminar

 

 

 

 

 

Materials Informatics for Heat Transfer

Junichiro Shiomi

Univeristy of Tokyo

 

2pm, Friday, February 16, 2024

Ryan Hall, rm. #4003

2190 Campus Drive, Evanston, IL 60208

 

Over recent decades, significant advancements have been made in developing thermal functional materials via nanostructuring. Nanostructures, with dimensions comparable to or smaller than the phonon transport's characteristic length, notably decrease thermal conductivity. This is beneficial for thermoelectrics and thermal insulators. When viewing phonons as particles, the characteristic length corresponds to their intrinsic mean free path during incoherent collisions. Nanostructures' surfaces and interfaces shorten this path, impacting heat conduction. Alternatively, considering phonons as waves, their characteristic length is their coherence length. Nanostructures with surface roughness smaller than the phonon wavelength can create interference, hindering phonon propagation. This nanostructure influence on phonon transport varies with the phonon's frequency, wavevector, and polarization, allowing for the spectral control of heat conduction. Thermal radiation is simpler, as its wavelength and coherence length are much larger. Larger structures can enable coherent and spectral control of photon transport. Nanostructuring significantly increases the degrees of freedom in structure design. The challenge lies in identifying the optimal nanostructure to maximize the desired figure of merit (FoM). This is where Materials Informatics (MI) becomes invaluable, aiding material development and study through informatics or machine learning. MI's application in heat transfer and thermal functional materials, although a later development compared to other fields, is now showing promising compatibility. Typical MI approaches involve training a model to correlate basic descriptors (structure, composition, etc.) with the target FoM, then predicting or designing materials with the highest FoM. At the Thermal Energy Engineering Lab, University of Tokyo, and in collaboration with others, we have pursued MI in heat transfer since 2015. One of our early projects involved designing binary multilayered nanostructures to optimize thermal conductance using thermal transport calculations and Bayesian optimization, proving highly efficient. Subsequently, by employing quantum annealing, we significantly expanded our search space. Our methods have been applied to computationally design and experimentally realize aperiodic superlattices and multilayer metamaterials that optimally impede coherent thermal transport and allow for wavelength-selective thermal radiation. This has now evolved into autonomous MI experiments. In my talk, I will outline these developments and discuss MI's potential in heat transfer, along with the challenges that remain for further progress.

Junichiro Shiomi is Professor in Institute of Engineering Innovation, School of Engineering, the University of Tokyo (UTokyo). He received B.E. (1999) from Tohoku University, and Ph. D. (2004) from Royal Institute of Technology (KTH), Sweden. Leading the Thermal Energy Engineering Lab, he has been pursuing research to advance thermal management, waste heat recovery, and energy harvesting technologies based on nano-to-macro innovation in materials, structures, and systems. Dr. Shiomi has been leading several projects including Grant-in-Aid for Scientific Research (S) (JSPS), Core Research for Evolutional Science and Technology (JST-CREST), Precursory Research for Embryonic Science and Technology (JST-PRESTO), and New Energy and Industrial Technology Development Organization (NEDO) projects. He is Fellow of Japan Society of Mechanical Engineers and Member of Science Council of Japan. He serves as an associate editor of Nanoscale and Microscale Thermophysical Engineering. He is a recipient of the Zeldovich Medal from the Committee on Space Research, the Commendation for Science and Technology by the Minister of Educational, Culture, Sports, Science and Technology, the Academic award of Heat Transfer Society of Japan, the Academic Award of Thermoelectric Society of Japan, the JSPS Award, and the Nukiyama Memorial Award.