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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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62 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Synthesis of U 3 O 8 and UO 2 microspheres using microfluidics

Uranium-bearing microspheres below 50µm with a narrow size distribution allows for a wider variety of fuel forms. To accommodate the smaller size, gel microspheres with a composition of UO 3 ∙nH 2 O∙mNH 3 were synthesized using microfluidics and subsequently converted to U 3 O 8 and UO 2 . To accommodate the slower flow rates required by microfluidics, a more stable broth was established. Additionally, the gelation studies resulted in a broth that was stable for more than two days at 0°C and for close to 3 h at room temperature while still gelling within 25 s. Synthesis of gel microspheres with a narrow size distribution lasted for 5 h and produced ~0.5 g of air-dried material. The gelled microspheres were converted to U 3 O 8 and UO 2 and with sizes of 50 and 40 µm in diameter, respectively.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Next Gen High Efficiency Boosted Engine Development

This work represents an advanced engineering research project partially funded by the U.S. Department of Energy (DOE). Ford Motor Company, FEV North America, and Oak Ridge National Laboratory collaborated to develop a next generation boosted spark ignited engine concept. The project goals, specified by the DOE, were 23% improved fuel economy and 15% reduced weight relative to a 2015 or newer light-duty vehicle. The fuel economy goal was achieved by designing an engine incorporating high geometric compression ratio, high dilution tolerance, low pumping work, and low friction. The increased tendency for knock with high compression ratio was addressed using early intake valve closing (EIVC), cooled exhaust gas recirculation (EGR), an active pre-chamber ignition system, and careful management of the fresh charge temperature. Engine weight reduction measures were implemented throughout the engine system making use of composite materials, advanced manufacturing techniques, and architectural choices. This report outlines the analytical, design, fabrication, and test work conducted for the duration of the project. The combustion system stability, EGR tolerance, and knock resistance were validated on a single cylinder engine. An inline six-cylinder engine was then designed targeting application in the Ford F150. Multi-cylinder engines were produced and tested achieving the target vehicle fuel economy improvement of 23% assessed using measured engine fuel consumption combined with a vehicle drive cycle simulation. Actions were identified and designs were demonstrated to achieve the 15% weight reduction target. This project included items covering a range of technology readiness levels. Some of the technologies explored are production ready, while others were investigated to understand the limitations for what can be achieved in a stoichiometric, gasoline-fueled, spark-ignited internal combustion engine.

42 ENGINEERING↗
DOE OSTI2021

Numerical Modelling of a Two-Body Point Absorber Featuring Variable Geometry

This work presents a novel wave energy converter (WEC) device concept that incorporates variable geometry modules into a two-body point absorber type WEC. The variable geometry modules consist of air inflatable bags in the surface float and a water inflatable ring in the reaction body. The variable geometry floats are able to provide greater control over the device hydrodynamics; they can be inflated or deflated to emphasize either power absorption or load shedding. The device geometry is controlled in a quasi-static fashion, while the power take-off (PTO) unit is controlled on a wave-to-wave timescale. The surface float is tethered directly to the submerged reaction body through PTO tether lines. A linear time-domain analysis, conducted using open-source Wave Energy Converter (WEC-Sim) software, was used to estimate the absorbed power of the WEC in sea states defined by the Wave Energy Prize. WEC power performance was weighted against the expected capital cost of building the load bearing structure of the device, providing an estimated ACE value. The inclusion of the variable geometry modules was shown to be effective in altering the device geometry to improve power capture with a near proportional increase in expected costs, providing a nearly constant power-to-cost ratio.

cost of energy↗
DOE OSTI2021

The toughest animals of the Earth versus global warming: Effects of long‐term experimental warming on tardigrade community structure of a temperate deciduous forest

Abstract Understanding how different taxa respond to global warming is essential for predicting future changes and elaborating strategies to buffer them. Tardigrades are well known for their ability to survive environmental stressors, such as drying and freezing, by undergoing cryptobiosis and rapidly recovering their metabolic function after stressors cease. Determining the extent to which animals that undergo cryptobiosis are affected by environmental warming will help to understand the real magnitude climate change will have on these organisms. Here, we report on the responses of tardigrades within a five‐year‐long, field‐based artificial warming experiment, which consisted of 12 open‐top chambers heated to simulate the projected effects of global warming (ranging from 0 to 5.5°C above ambient temperature) in a temperate deciduous forest of North Carolina (USA). To elucidate the effects of warming on the tardigrade community inhabiting the soil litter, three community diversity indices (abundance, species richness, and Shannon diversity) and the abundance of the three most abundant species ( Diphascon pingue , Adropion scoticum , and Mesobiotus sp.) were determined. Their relationships with air temperature, soil moisture, and the interaction between air temperature and soil moisture were tested using Bayesian generalized linear mixed models. Despite observed negative effects of warming on other ground invertebrates in previous studies at this site, long‐term warming did not affect the abundance, richness, or diversity of tardigrades in this experiment. These results are in line with previous experimental studies, indicating that tardigrades may not be directly affected by ongoing global warming, possibly due to their thermotolerance and cryptobiotic abilities to avoid negative effects of stressful temperatures, and the buffering effect on temperature of the soil litter substrate.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Mitigation of Molten Salt Corrosion

The desire to increase the peak operational temperature of Concentrated Solar Power (CSP) plants to lower the levelized cost of CSP-derived electricity, has led to consideration of an earth-abundant, low-cost, thermally-stable, molten MgCl 2 -KCl-NaCl (40-40-20 mole%) salt for high-temperature thermal energy storage and heat transfer. The reliable, long-term containment of such a molten salt is challenging, however, due to the corrosion of cost-effective, high-temperature structural metal alloys in this salt (particularly if this salt is contaminated with oxygen-bearing species). This project has been focused on: i) development of equipment for evaluating corrosion kinetics in molten chlorides under well-controlled thermal, fluid dynamic, and atmospheric conditions at CSP-relevant temperatures, ii) use of such equipment to evaluate the influence of forced convection on corrosion kinetics (to determine the role of liquid phase diffusion on such corrosion), and iii) identifying a corrosion-mitigation strategy that can be industrially applied to achieve a projected annual corrosion ≤30 μm at CSP-relevant temperatures. The overall goals of this project have been: i) to understand the rate-limiting step(s) and associated kinetic laws governing corrosion in molten chlorides at 750°C, ii) to determine key operational parameters affecting the corrosion kinetics in molten salts, and iii) to demonstrate the tailoring of such parameters to appreciably reduce such corrosion.

14 SOLAR ENERGY↗
DOE OSTI2025

Alkaline Earth-Based Ternary Chalcogenide Nanocrystals: Cadmium- and Lead-Free Optical Materials

As some of the most abundant elements on the Earth’s crust, alkaline earths bear great potential in Cd- and Pb-free catalytic, energy conversion, and light-emitting devices. Further, because large electropositive alkaline earths (Ae) can adopt high coordination numbers, they offer structural complexity beyond the tetrahedral (c-Si, II–VI, III–V) or octahedral (IV–VI) atomic sites that─with the notable exception of halide perovskites─are ubiquitous among nanocrystalline semiconductors. Here, in this work, we present a general route to photoluminescent 6–125 nm nanocrystals of ternary AeIn 2 Ch 4 semiconductors (Ae = Sr, Ba; Ch = S, Se) featuring eight- (Ae) as well as four-coordinate (In and Ch) atomic sites. Powder X-ray diffraction, electron microscopy, optical absorption, photoluminescence, and solid-state (ss)NMR spectroscopies attest to the ternary composition and phase purity of the nanocrystals. Continuous shape measures pinpoint the degree of distortion of individual crystallographic sites from ideal coordination polyhedra, allowing us to identify two very distinct types of Se coordination environments. Based on their higher order, pseudo-3-fold rotational symmetry, we assign 77 Se ssNMR peaks with negligible chemical shift anisotropy (CSA) to pyramidalized Se sites with vacant-trigonal bipyramid-like geometries and those with larger CSA to lower symmetry Se sites with seesaw-distorted geometries. Calculations help to better understand the electronic band structure of these materials. The nanocrystals are stable at room temperature in open air for several weeks, and some compositions up to 1000 °C under Ar, making them strong candidates for practical applications.

alkaline earth↗
DOE OSTI2020

Retrieval of Transuranic Drums with Deflagration to Detonation Potential from a Vault at the Oak Ridge National Laboratory - 20207

During the final phase of a long-term project, a total of 80 TRU waste drums at ORNL have been retrieved from a below-grade storage vault in which they have remained untouched for about 25 years. The drums, which house material generated from past ORNL operations, are now stored and ready for eventual transfer to the Transuranic Waste Processing Center, located on Highway 95 in Oak Ridge. The Transuranic Waste Processing Center will process and ship the drums to WIPP in Carlsbad, New Mexico, for disposal. Workers lifted the drums one-by-one from the underground storage vault with a 110-ton crane over a one-week period in October 2017. Although the physical work was performed in one week, years of detailed planning preceded the fieldwork. A key obstacle needed to be overcome before the project could safely proceed. This obstacle involved the need to ensure controls were developed for the Deflagration to Detonation Transition (DDT) potential. DDT refers to a phenomenon in ignitable mixtures of a flammable gas and air (or oxygen) when a sudden transition takes place from a deflagration type of combustion to a detonation type of explosion. Basically, these drums, under certain circumstances, have a potential to detonate and overpressurize. Extensive analysis of the drums verified that detonation, while unlikely, was possible. Of the total 103 drums that were retrieved or moved in preparation for retrieval, 18 had DDT potential. Extensive security requirements were also necessary, due to the nature of the material, and this added another layer of complexity to the fieldwork. Prior to retrieving the drums from the underground storage vault, space needed to be made for them within the various above-grade facilities. Inventory and security requirements dictated what could be stored where, and the first step of the field work involved a number of drum movements in preparation for storage of the newly retrieved drums. This effort involved moving 21 drums already in the storage area to facilitate the addition of the newly retrieved ones. The retrieval project required a total of 107 critical lifts using the 110-ton crane, under 3 critical lift plans. The TRU waste storage facility is a Category 2 Nuclear Facility and is managed under an extensive Documented Safety Analysis. The TRU retrieval project was conducted in accordance with DOE Order 425.1D and included three Implementation Verification Reviews, two Management Assessments, one Readiness Assessment, and seven mock-ups in preparation for the field work. Despite being stored for 25 years, the drums were in good shape due to the integrity of the facilities where the drums were stored. Of the 80 drums that were retrieved, 12 were placed in special containers called 'overpacks' based on their content. The drums were removed safely and without incident, thanks to a lot of preparation and the efforts of a highly skilled team. Lessons learned through the DDT control development and the drum retrieval and overpacking process could be beneficial to others having to manage similar drums of TRU waste. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Amapari Marker Band Metal‐Enrichments: Potential Mechanisms and Implications for Surface and Subsurface Water and Weathering in Gale Crater

NASA's Curiosity rover is exploring a 5 km tall sedimentary mound that is hypothesized to record the transition from a warm and wet (phyllosilicate-rich) to a cold and drier (sulfate-rich) Mars. Evidence of magnesium sulfate-bearing rock has shown that Curiosity has crossed through this phyllosilicate-sulfate transition. Recently, Curiosity arrived at the Amapari Marker Band, a darker, indurated unit that can be traced laterally for tens of kilometers in orbiter images. Here, Curiosity found evidence for a very broad lake, and bedforms interpreted as wave-ripple laminated sedimentary rock that likely was deposited in shallow water in the explored location, before becoming a deeper lake. These rocks are enriched in Fe, Mn, and Zn which has major implications for groundwater paleohydrology in Gale crater. Three formation hypotheses are considered: concretion formation during early diagenetic alteration of shallow lake sediments, laterization or leaching of the sediments, and addition of Fe, Mn, and Zn by a mildly acidic and reducing groundwater interacting with a redox and/or pH front in a stratified lake. The preferred interpretation of the metal enrichments within the Amapari Marker band sedimentary rocks is that they formed in a shallow water environment at a redox and/or pH front within the ripple unit, which drove precipitation and concentration of metals. If the enrichments are due to groundwater alteration, these processes could link subsurface and surface environments. Water and the presence of high amounts of redox sensitive elements and other metals are favorable indicators for habitability.

58 GEOSCIENCES↗