Month: November 2018

A new paper has come out.

November 24, 2018
Our research in collaboration with Prof. Jungchul Lee’s group at KAIST (Korea) has been published in Micro and Nano Systems Letters. The paper title is “Hydrogel tip attached quartz tuning fork for shear force microscopy”. Abstract:
This paper reports the first demonstration of hydrogel conical tip attachment onto quartz tuning fork (QTF) by using an elastomeric tip mold that is soft-lithographically replicated from an electrochemically etched tungsten wire. The tungsten tip of 10–100 nm radius obtained by time-controlled electrochemical etching is replicated with h-polydi- methylsiloxane (h-PDMS) to make negative conical tip molds large enough to be used for QTFs. By approaching a QTF to the negative h-PDMS tip mold filled with polyethylene glycol-diacrylate (PEGDA), a PEGDA tip is attached to the QTF without using an adhesive. Then, the PEGDA tip attached QTF is employed for shear force microscopy for calibration grating and atomic layers of hexagonal silicon carbide and also compared with a silicon tip attached QTF. Exclusively for the PEGDA tip attached QTF, we demonstrate that the imaging tip could be regenerated multiple times to address issues associated with tip wear. In a stark contrast with conventional QTF probes in attachment of electro- chemically etched metallic wires or microfabricated AFM cantilevers, photocuring of liquid phase prepolymer within a tip mold demonstrated herein allows adhesive-free and exclusive attachment of the imaging tip onto a QTF. The relatively large PEGDA tip enables facile operation during approach and engagement. Moreover, the organic and inor- ganic combination of imaging tip and resonating body offers regeneration of the imaging tip upon its degradation.

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

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.