Utah Nanoscale Thermal Transport (NT2) LabFunding Highlights – Utah Nanoscale Thermal Transport (NT2) Lab

DOE Funding for Volumetrically Absorbing Thermal Insulator (VATI) for Monolithic High-Temperature Microchannel Receiver Modules

Cedric Shaskey — Mon, 19 Nov 2018 19:51:26 +0000

The U would like to announce that it was selected to receive a $500,000 award from the U.S. Department of Energy Solar Energy Technologies Office (SETO) to advance concentrating solar-thermal power (CSP) research and development. This project will explore a novel approach to improve the overall solar to thermal collection efficiencies by reducing both optical and thermal losses.

Critical to enabling large-scale concentrated solar thermal power conversion is to maximize the concentrated solar to thermal efficiency. This project will explore volumetric absorption within porous structures which are monolithically integrated with microchannel modules. Solar-thermal conversion in such a module will improve the overall receiver efficiency by simultaneously reducing optical and thermal losses at temperatures in excess of 720 °C.

Several approaches have been explored to reduce optical and thermal losses for high-temperature CSP applications, but most approaches are unsuited for prolonged operation at temperatures in excess of 720 °C. Volumetric absorption within carefully tailored porous refractory materials can enable volumetric absorption of incident solar radiation, reflected optical losses, and re-emitted thermal losses to improve receiver efficiency. The project will explore detailed considerations of coupled optical and radiative thermal transport to develop optimized porous geometries for a wide variety of operating considerations. In addition, these structures are monolithically integrated to a microchannel module which in turn enables the efficient transfer of thermal energy at high heat fluxes.

The University of Utah was selected as a part of the Energy Department’s FY2018 SETO funding program, an effort to invest in new projects that will lower solar electricity costs and support a growing solar workforce. The U is one of several CSP projects that will develop materials and designs for collectors, power cycles, and thermal transport systems that can withstand high temperatures and resist corrosion.

The project will utilize refractory materials which are suited for long-term operation at elevated temperatures. This robust module with its long service life, low cost, and high efficiency can play an important role in reducing the cost of CSP technology.

About the U Investigators

The performance team is composed of University of Utah mechanical engineering assistant professor Sameer Rao (principal investigator) in the Energy Science and Engineering Laboratory, associate professors Mathieu Francoeur (co-principal investigator) of the Radiative Energy Transfer Laboratory and Keunhan Park (co-principal investigator) of the Utah Nano-Energy Laboratory.

About the Solar Energy Technologies Office

The U.S. Department of Energy Solar Energy Technologies Office supports early-stage research and development to improve the affordability, reliability, and performance of solar technologies on the grid. Learn more at energy.gov/solar-office.

Ghashami receives a U Graduate Research Fellowship

Mon, 23 Jul 2018 16:26:46 +0000

The Department of Mechanical Engineering is excited to announce that Ph.D. student, Mohammad Ghashami received a University of Utah Graduate Research Fellowship from the Graduate School. Advised by mechanical engineering associate professor Keunhan “Kay” Park, Ghashami is a member of the Utah Nano-Energy Laboratory. A Graduate Research Fellowship (GRF) is a one-year, non-renewable award of which full-time students working towards their Ph.D. qualify. Selection criteria is based on the quality and impact of the student’s research, as well as their achievements (published papers, conference presentations, etc.) and their potential for success; i.e., academic excellence (assessed by academic record and references.) About receiving a GRF, Ghashami said, “I was thrilled to be selected to receive this prestigious award. It is a significant help in allowing me focus on my work during this, the last year of my Ph.D. program.” As a mechanical engineering undergraduate at the University of Tehran, Iran, Ghashami studied hybrid dry cooling towers and solar chimney to improve the overall efficiency of a thermal power plant. “Thinking of ways to improve the efficiency of our daily-used energy-based systems for my senior thesis,” said Ghashami, “triggered the idea of pursuing a graduate degree. In Iran the stiff competition motivated me to seek the best research opportunities in the world.” “My search led me to Dr. Park’s multidisciplinary research on energy conversion, nanoscale heat transfer, and microfabrication. At the time, Dr. Park was in transition from the University of Rhode Island to the University of Utah. Realizing he was building a new strong research team at the U, the timing was perfect for me!” Currently Ghashami’s work focuses on experimental investigation of near-field thermal radiation and its applications for energy conversion. Using this concept, he believes there is a great potential to recycle the waste heat to generate cheap and accessible electricity. Ghashami explains, “The total energy lost as heat in the U.S. in 2012, could supply seven years’ worth of power to the entire United Kingdom. This clearly shows the importance of finding new methods that enable us to recycle this wasted heat in our daily life. Near-field thermal radiation might be one of the newest and most promising concepts that opens up new possibilities for energy conversion.” On a personal note, Ghashami loves playing sports, especially soccer, and enjoys Utah outdoor activities including skiing, hiking, and biking. In his spare time he is also very fond of Persian literature and poetry.

Cedric Shaskey receives 2017 NSF Fellowship

Mon, 03 Apr 2017 18:46:19 +0000

Congratulations Cedric Shaskey for receiving the National Science Foundation Graduate Research Fellowship! Native of Salt Lake and a graduate from Olympus High School before attending the University of Utah, undergraduate Cedric Shaskey, B.S.’17 double majoring in mechanical engineering and physics, is a recipient of a prestigious 2017 National Science Foundation (NSF) Graduate Research Fellowship, which covers tuition, fees, and a significant stipend for up to three years towards his doctorate degree. Additionally, he is a recipient of the College of Engineering Campbell Endowed Graduate Fellowship, which he plans to use towards the first year in his Ph.D. program. With his fellowships he will also have access to special opportunities for international research and professional development. Shaskey said, “Everything fell in to place after taking Thermodynamics II and joining the Micro/Nanoscale Energy Transport and Conversion (METAC) Laboratory, advised by mechanical engineering assistant professor Keunhan Park.” His dual degree and interest in nano-engineering aligned with the multidisciplinary, nanoscale research being conducted in the METAC lab. Plus the mentorship of Dr. Park and mechanical engineer Ph.D. candidate and member of the lab, Amun Jarzembski, cemented his desire to pursue a career in nanotechnology. During his time as an undergraduate in the METAC, Shaskey has presented his research at the Utah Conference on Undergraduate Research, Research on Capitol Hill and the National Conference of Undergraduate Research. He was twice supported by the Undergraduate Research Opportunities Program at the University of Utah. An avid outdoorsman, Shaskey said, “A vast wilderness reminds me that the smallest elements combine to make the grandness of our universe and that by understanding nature on the smallest scale, you can begin to understand and manipulate it on the largest scale. This idea has inspired me to pursue a career in nanotechnology in the hope of broadly improving the quality of life by contributing to human understanding at the smallest scale.” Shaskey’s research involves scattering-type near-field scanning optical microscopy (s-NSOM), which is a novel scanning probe microscopy that breaches the diffraction limit by collecting light scattered from an oscillating atomic force microscope (AFM) probe tip. The spatial resolution of s-NSOM depends only on the tip sharpness (typically on the order of 10nm) enabling nanoscale optical imaging. His hypothesis is that tip-scattering is conceptually analogous to far-field reflectance and thus sensitive to temperature. His Ph.D. research will seek to use this correlation to realize a non-invasive, optical characterization technique with spatial resolution on the order of 10 nm by integrating s-NSOM with the pump-probe thermoreflectance scheme to enable probing of the spectral thermal conductivity accumulation function at the nanoscale in order to advance the understanding of phonon mean free path spectrum and its effects on thermal transport. Cedric’s academic career is eclectic. He first got involved in research as a freshman when he joined the Organic Light Emitting Diode (OLED) Lab in the Physics and Astronomy Department. Through his time there, he fabricated OLED devices from scratch and tested their response to magnetic fields and temperature. The following year, he ran a house painting business. Within six months, the business grossed more than $25,000; while attending classes, he simultaneously organized six employees to complete sixteen projects with a 100% customer satisfaction rating. In his third year at the University, Shaskey joined the Honors College Think Tank on the Uneasy Intersection of Law and Medicine. They developed the notion of post-prescription management – the idea that a physician’s commitment does not end with a signature on the prescription pad; that what happens after the prescription has been written is of pivotal importance to the patient, to the prescriber and to the community at large. It was during his fourth year that Shaskey joined the Senator Bennett Seminar. Being the only science and engineering student to join the discussion revealed the importance of an active scientific community in the political process. In the future, Cedric hopes to form a student group with the goal of increasing political activity among academics. In addition to academics, Shaskey is an accomplished outdoorsman. He has led over 30 three to five day excursions into mountain ranges across the western United States, including summiting the highest peaks in Utah, Wyoming, Idaho and Nevada. Cedric also organizes, coaches and plays on a recreational soccer team – he is a huge fan of the Utah Jazz, Real Salt Lake and Bayern Munich. The purpose of the NSF Graduate Research Fellowship Program (GRFP) is to help ensure the vitality and diversity of the scientific and engineering workforce of the United States. The program recognizes and supports outstanding graduate students who are pursuing research-based master’s and doctoral degrees in science, technology, engineering, and mathematics (STEM) or in STEM education. Cedric Shaskey’s NSF GRFP is based on his demonstrated potential to contribute to strengthening the vitality of the U.S. science and engineering enterprise.

P.-E. Gaillardon and K. Park awarded University of Utah RIF

Mon, 05 Dec 2016 18:52:03 +0000

Congratulations to Professors Pierre-Emmanuel Gaillardon and Kay Park who recently received a University of Utah Research Instrumentation Fund for “Shared High-Resolution Nanolithography System”. This fund will help bring the SwissLitho AG NanoFrazor to the University of Utah Nanofab cleanroom facility. The SwissLitho NanoFrazor will provide:

High‐resolution direct write nanolithography: Resist is directly vaporized during the NanoFrazor patterning process and hence no development and no proximity correction is necessary. This enables patterning of complex shapes that are not possible to achieve with e‐beam The written shape reflects the tip geometry. Resolution below 50 nm half‐pitch is achieved on a regular basis, below 10 nm has been demonstrated.
3D nanolithography: 3D topographical structures can be written in just one step and with unmatched accuracy. Patterning of resists like PPA allows better than 2nm vertical
In‐situ topography imaging: The NanoFrazor Scholar uses the same tip for patterning as well as for imaging the topography of the substrate with sub-‐nm vertical resolution and single nanometer lateral resolution.
Closed-‐loop lithography: The final shape of the written pattern is continuously measured. Deviations from the target are used as input for immediate automated adjustments of the patterning parameters, like e.g. the applied contact force of the tip to the
Stitching and overlay: The in‐situ topographic imaging capability also enables possibilities for stitching and overlay. The natural surface roughness of the resist provides perfect properties for field stitching using correlation techniques without any marker structures. Furthermore, the remaining topography of nanostructures (e.g. nanowires) buried under the spin‐coated resist is also detectable, allowing extremely accurate overlay alignment to these structures (e.g. nanowires) is achieved.
No damage from charged particle beam: Beam‐based nanolithography technologies, such as electron or ion beam, can charge substrate materials and often permanently damage the The resist in e‐beam lithography absorbs only a small fraction of the beam energy and the majority of the beam energy is actually absorbed by the substrate. This is in contrast to the NanoFrazor, where the energy in form of heat is largely absorbed in the top layer of the resist stack. Heating of the underlying substrate is negligible and delicate materials stay unharmed.

Thermal nanoscale experiments: The temperature of the tip’s microheater can be controlled accurately between room temperature and up to around 1000°C. This allows precise triggering of chemical reactions or phase transitions at the nanoscale besides the usual topographical nanopatterning by evaporating resists. In addition, a wide range of contact forces and reaction times can be applied to study such reactions or to find the optimum chemical patterning conditions for any new materials being tested.

The NanoFrazor technology is currently available in the following institutions: ETHZ (Switzerland), EPFL (Switzerland), IBM Research (Switzerland), Beihang University (China), Melbourne University (Australia), McGill (Canada) and Air Force Research Laboratory (USA). As a result, we will be the first university in the US to acquire this technology providing us a competitive advantage to obtain research results exploiting the capabilities of the tool and helping us secure new grants.

Park receives University of Utah Seed Grant

Sun, 04 Dec 2016 17:10:35 +0000

Congratulations to Prof. Kay Park! He recently received a University of Utah Seed Grant for the “Development of Scanning Near-Field Thermoreflectance Microscopy for Nanoscale Temperature and Phonon Mean Free Path Spectra Mapping”. Understanding of thermal transport at the nanoscale has increasing importance as device sizes shrink and applications for nanotechnology become more prevalent. At these length scales, the device size is often comparable to the mean free paths (MFPs) of energy carrying particles, particularly phonons for semiconducting and dielectric materials, causing the selective scattering of phonons and ballistic heat conduction across the boundaries. The reduction of the thermal conductivity due to such non-Fourier heat conduction has a huge impact on heat dissipation of nanoelectronic and photonic devices, often leading to the operation failure due to overheating. However, the spectral distribution of phonons and its impact to the thermal conductivity is not yet fully understood, mainly due to lack of adequate instrumentation of spectral phonon transport properties. The ultimate goal of the proposed research direction is to directly measure a nanoscale and broadband probing of phonon spectra for fundamental research of nanoscale heat conduction. To this end, we propose to implement the broadband frequency-domain thermoreflectance (BB-FDTR) scheme to scanning near-field optical microscopy (SNOM). The so-called scanning near-field thermoreflectance microscopy (SNTRM) is based on the hypothesis that tip-scattered near-field optical signal essentially has the same information about a sample’s optical properties as the conventional optical reflectance signal except the subwavelength spot size, and thus should be sensitive to the temperature change. Therefore, a nanoscale thermoreflectance scheme will be possible by measuring temperature-dependent tip-scattered near-field light, which can provide the thermal conductivity accumulation function at the nanoscale as a function of the phonon MFP.

Park receives $300K NSF Grant

Thu, 04 Aug 2016 22:45:26 +0000

Congratulations to Prof. Kay Park! He recently received a National Science Foundation grant for $299,998 on “Fundamental Studies of Near-field Enhancement in Thermionic Energy Conversion”. In 2014, Unites States consumed more than 97 quadrillion Btu of energy. This is equivalent to the amount of energy in 3.5 billion tons of coal or 776 billion gallons (US) of gasoline. However, almost 59% of such energy consumption is being lost as waste heat. It is thus imperative to find an innovative way of recycling energy from a waste heat source as an emission-free and less-costly energy resource. The objective of this project is to explore the near-field enhancement of thermionic emission for renewable energy recycling. Conventional thermionic energy conversion (TEC) generally requires a high cathode temperature over 1500K to thermally excite enough electrons from the cathode overcoming its binding potential, or work function, for power generation. Low efficiency is another challenging issue of TEC power generation. Park’s group will address this challenge by implementing a low bandgap semiconducting material as a cathode and placing it a subwavelength distance away from a thermal emitter. They hypothesize that the near-field enhancement of thermal radiation will boost the photoexcitation of electrons in the low-bandgap semiconductor cathode, significantly increasing the thermionic current density. In addition, the energy conversion efficiency will be substantially improved because the most radiation absorbed in the cathode will benefit thermionic emission, i.e., photoexcitation from the photon energy slightly above the cathode bandgap and thermalization from the excess photon energy and sub-bandgap photon energy. The success of this project will make a transformative impact to thermionic power generation as a possible way of renewable energy recycling. The project will also promote training and learning by involving students in micro/nanofabrication, thermal and infrared characterization of nanodevices, nanoscale heat transfer measurements, and nanoscale instrumentations.

Park and Francoeur receive $350K NSF Grant

Thu, 04 Aug 2016 16:20:41 +0000

Professors Mathieu Francoeur and Kay Park received a three-year NSF grant of $350,000 for their research on “Extreme Near-Field Thermal Radiation at Sub-10-nm Vacuum Gap Distances.” The objective of the research is to experimentally and theoretically investigate extreme near-field thermal radiation by: (1) measuring extreme near-field radiative heat transport between a heated tip and a surface in an ultrahigh vacuum atomic force microscope; (2) measuring the near-field thermal spectrum via tip-enhanced photocurrent generation and tip-scattered thermal radiation; and (3) modeling tip-surface near-field thermal interactions via numerically exact and approximate methods. The outcome of this research will provide knowledge on the spectral distribution of thermal radiative energy and its transport in the extreme near-field regime, and will spark the development of detection, imaging, and spectroscopy of mid-infrared light at the nanoscale as well as near-field thermophotovoltaic power generators.

Amun Jarzembski receives 2016 NSF Graduate Research Fellowship

Tue, 29 Mar 2016 19:07:33 +0000

Congratulations Amun Jarzembski for receiving the National Science Foundation Graduate Research Fellowship! The NSF GRF will support Amun’s Ph.D. work for three years. Amun’s research involves the exploration of near-field thermal radiation from a nanoscale heated tip to planar substrate for sub-10nm gaps. Since the discovery that near-field thermal radiation can exceed Planck’s blackbody limit by several orders of magnitude, experimental and theoretical studies of its spectrum and gap dependence have become crucial to the understanding of waste heat energy conversion devices, nanoscale thermal management systems, and sub-continuum heat transfer. The use of a heated tip allows for simultaneous measurement of absorbed and scattered thermal radiation which enables spectroscopic measurements. His research aims to fundamentally understand the infrared (IR) light-matter interactions that govern the spectral and absorbed near-field thermal radiation for varying gaps and materials. Objectives of this project: • Determine the gap dependence of absorbed near-field thermal radiation to sub-10nm gap regime. • Measure the spectrum of tip-scattered near-field thermal radiation for various materials. • Directly measure the spectrum of near-field thermal radiation and compare with the corresponding tip-scattered spectrum. To conduct this research, the Micro/nanoscale Energy Transport and Conversion Lab (METCL) has an ultra-high vacuum atomic force microscope (AFM) with scattering-type scanning near-field optical microscopy capabilities. This optical AFM allows for atomic resolution topographic and nanoscale optical microscopy. Additionally, METCL is equipped with a tunable mid-IR laser source that provides the ability to perform nanoscale mid-IR microscopy and spectroscopy. This combination of instruments puts the METCL lab in the unique position to conduct tip-based near-field thermal radiation experiments to comprehensively understand nanoscale radiative phenomenon. Additional milestones of this research include near-field opto-thermal measurements for the determination of nanoscale temperature distributions, nanoscale IR spectroscopy for material characterization, and near-field photocurrent measurement on thin film solar cells. Amun graduated from the University of Alabama in Huntsville (UAH) with a bachelor’s degree in mechanical engineering and received their Most Outstanding Undergraduate Mechanical Engineering Student Award. While at UAH, he participated in several student driven projects and worked on radar systems for Raytheon Huntsville. His fascination with the thermal sciences began when he designed an algorithm to compute building heat transfer for a residential house based on local weather and solar data. However, being the son of two NASA physicists who specialized in optics and lasers, inherently he found the most fascination with energy carried by radiation. When Dr. Park provided the opportunity for him to build up a nanoscale optics lab with focus on thermal radiation and energy conversion, he knew the fit was too perfect! Through the NSF Graduate Research Fellowship, Amun will have the financial support of the National Science Foundation including an annual stipend of $34,000 and a $12,000 cost of education allowance for tuition and fees. He also will have access to special opportunities for international research and professional development, and the freedom to conduct their own research at any accredited U.S. institution of graduate education they choose (nsfgrfp.org/general_resources/about).