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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3

Theoretical face pressure and drag characteristics of forward-facing steps in supersonic turbulent boundary layers

A theoretical investigation of the pressure distributions and drag characteristics was made for forward facing steps in turbulent flow at supersonic speeds. An approximate solution technique proposed by Uebelhack has been modified and extended to obtain a more consistent numerical procedure. A comparison of theoretical calculations with experimental data generally indicated good agreement over the experimentally available range of ratios of step height to boundary layer thickness from 7 to 0.05.

Patel, D. K.↗

On the challenges facing the handling of solid biomass feedstocks: On the Challenges Facing the Handling of Solid Biomass Feedstocks

With a major global emphasis on the management of waste, alternative resources and a shift to environmentally sustainable technologies, demand for large volumes of heterogeneous solid biomass feedstocks for energy or chemical use is expected to rise significantly. In transforming a sporadic supply of a low-value, highly variable product, to continuous and controlled high throughput systems, a thorough understanding of the feedstock properties will increase in importance. Appropriate characterisation tests are necessary to define technical specification and selection criteria for handling equipment and to appraise the requirement and location for additional processes or pre-treatment to be integrated into the handling chain. Such tests may also influence the material characteristics to be used in the conversion process. In this paper, we discuss the main feedstock attributes associated with a number of handling chain phases and the approach to obtain them. Lastly, the framework for a holistic approach to the characterisation and design of biomass feedstock handling systems for further development and practical implementation is also proposed.

09 BIOMASS FUELS↗

A Critical Review of Challenges Faced by Converting Food Waste to Bioenergy Through Anaerobic Digestion and Hydrothermal Liquefaction

Here, the conventional approaches for handling food waste has been incineration, composting, landfilling, and anaerobic digestion for producing biogas. In light of organic waste bans and newly discovered presence of per- and polyfluorinated substances (PFAS) in food, food packaging materials, and compost, this review provides a critical summary of what has been investigated and reported and what needs to be considered when choosing suitable pathways for food waste. In addition to the fundamental principles inherent to anaerobic digestion and hydrothermal liquefaction, challenges for each process are identified followed by discussion of potential solutions to resolve the bottlenecks.

09 BIOMASS FUELS↗

System design of a 1 MW north-facing, solid particle receiver

Falling solid particle receivers (SPR) utilize small particles as a heat collecting medium within a cavity receiver structure. The components required to operate an SPR include the receiver (to heat the particles), bottom hopper (to catch the falling particles), particle lift elevator (to lift particles back to the top of the receiver), top hopper (to store particles before being dropped through the receiver), and ducting. In addition to the required components, there are additional features needed for an experimental system. These features include: a support structure to house all components, calibration panel to measure incident radiation, cooling loops, and sensors (flux gages, thermocouples, pressure gages). Each of these components had to be designed to withstand temperatures ranging from ambient to 700 °C. Thermal stresses from thermal expansion become a key factor in these types of high temperature systems. The SPR will be housing ~3000 kg of solid particles. The final system will be tested at the National Solar Thermal Test Facility in Albuquerque, NM.

14 SOLAR ENERGY↗

High temperature x ray diffraction determination of the body-centered-cubic-face-centered-cubic transformation temperature in (Fe{sub 70}Ni{sub 30}){sub 88}Zr{sub 7}B{sub 4}Cu{sub 1} nanocomposites

In situ high-temperature x ray diffraction and magnetization measurements were performed on a melt-spun (Fe{sub 70}Ni{sub 30}){sub 88}Zr{sub 7}B{sub 4}Cu{sub 1} amorphous alloy to follow its structural evolution. At 728 K, a bcc-FeNi phase was observed as the primary crystallization product followed by transformation to an fcc phase {approx}773 K. During cooling to room temperature, the fcc-to-bcc transformation was not observed, and the metastable fcc-NiFe phase was retained at room temperature.

36 MATERIALS SCIENCE↗