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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Geology of the Mohon Mountain volcanic field, Yavapai and Mohave Counties, Arizona: A preliminary report

Field mapping has produced a preliminary picture of Mohon Mountain as a composite volcano, in which pyroclastic ash and larger tephra erupted alternately with flows of rhyodacite and dacite. An analog study which uses imagery of lunar and Martian features will compare the overall shape of the vent complex, including its breached southern flank and satellite vents, to similar landforms found on Mars and the Moon which are believed to have formed similar processes. Ash flow sheets were hypothesized to comprise the outer slopes of Olympus Mons suggesting that explosive eruptions which are more volatile-rich than those which produce basalt flows are not confined to terrestrial settings but may also be found on bodies such as Mars, which have a thicker crust and deeper magma source in the mantle. The analog study will explore further evidence for explosive eruptions on Mars and the Moon.

Simmons, Ardyth M.↗
DOE OSTI2018

Development of Biocomposites from Agro Wastes for Low Dielectric Applications

The present work is attempting to synthesize and characterizations of a novel carbazole core containing cardanol based benzoxazine monomer from carbazole core containing aromatic diamine, cardanol and paraformaldehyde. In addition, carbazole core containing cardanol based benzoxazine polymer and various weight percentages of amine functionalized rice husk ash incorporated carbazole core containing cardanol based polybenzoxazine composites were prepared. The prepared polymer and its composites were characterized by FTIR, XRD, DSC, TGA and dielectric studies. The various studies confirm that the composites show increased Tg, higher char yield and better thermal stability compared to carbazole core containing cardanol based benzoxazine polymer. In addition to that the composites show significant decrease in the dielectric constant values than the neat cardanol based polybenzoxazine. The surface morphology and the distribution of rice husk ash in carbazole core containing cardanol based polybenzoxazine composites are confirmed by SEM and TEM analysis. Hence, the present study has attempted to prepared eco-friendly value added carbazole core containing cardanol based polybenzoxazine products for low dielectric constant applications by making use of biowaste for both matrix and reinforcement preparation to form biowaste based composites. Graphical Abstract: Schematic representation for the preparation of carbazole core containing cardanol based benzoxazine monomer, polybenzoxazine and biobased polybenzoxazine composites .

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Modeling ash deposition and shedding during oxy-combustion of coal/rice husk blends at 70% inlet O2

Abstract Co-firing rice husk (RH) and coal with carbon capture using oxy-combustion presents a net carbon negative energy production opportunity. In addition, the high fusion temperature of the non-sticky, silica rich, RH can mitigate ash deposition as well as promote shedding of deposits. To identify the optimum operating conditions, fuel particle sizes, and blend ratios that minimize ash deposition, a Computational Fluid Dynamic methodology with add-on ash deposition and shedding models were employed to predict outer ash deposition and shedding rates during co-combustion of coal/RH in AIR and O 2 /CO 2 (70/30 vol%, OXY70) oxidizer compositions. After ensuring that the fly-ash particle size distributions and particle Stokes numbers near the deposition surface were accurately represented (to model impaction), appropriate models for coal ash and RH ash viscosities that were accurate in the temperature region (1200–1300 K) of interest in this study were identified. A particle viscosity and kinetic energy (PKE) based capture criterion was enforced to model the ash capture. An erosion/shedding criterion that takes the deposit melt fraction and the energy consumed during particle impact into account was also implemented. Deposition rate predictions as well as the deposition rate enhancement (OXY70/AIR) were in good agreement with measured values. While the OXY70 scenario was associated with a significant reduction (60%–70%) in flue gas velocities, it also resulted in larger fly-ash particles. As a result, the PKE distributions of the erosive RH ash were similar in both scenarios and resulted in similar shedding rates.

Energy & Fuels↗
NASA NTRS1994

Proximate nutritional composition of CELSS crops grown at different CO2 partial pressures

Two Controlled Ecological Life Support System (CELSS) candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS.

Wheeler, R. M.↗
DOE OSTI2018

Influence of fiber inclination angle on bond-slip behavior of different alkali-activated composites under dynamic and quasi-static loadings

This study investigates the influence of inclination angle (0° and 45°) on the interfacial bond-slip behavior of macro steel fibers (straight, hooked end-deformed and length-deformed) and length-deformed polypropylene fibers reinforced in fly-ash and metakaolin based alkali-activated composites (AACs) under quasi-static and dynamic loadings. AACs demonstrate superior peak bond strength and toughness compared to cement composites regardless of fiber type and loading rate. Results also show that straight steel fiber exhibits a complete pullout in AACs. The amount of deformation of the fibers (deformation ratio) determined the failure type at different inclination angle and loading rate, thus governing the peak load and energy absorption. Depending on the fiber orientation, premature fiber rupture or matrix cracking is observed under dynamic loading in AACs due to matrix brittleness. The fiber failure modes in dynamic pullout are no different from those observed in the quasi-static pullout in AACs.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Leaching characteristics of toxic constituents from coal fly ash mixed soils under the influence of pH

Highlights: • The impact of pH on the leaching of elements and metals from fly ash mixed soils. • Generally Ca, Cd, Mg, and Sr follows a cationic leaching pattern. • The leaching of As and Se shows an oxyanionic leaching pattern. • The leaching behavior of elements does not change based on material type. • Different fly ash types show different abilities in immobilizing trace elements. - Abstract: Leaching behaviors of Arsenic (As), Barium (Ba), Calcium (Ca), Cadmium (Cd), Magnesium (Mg), Selenium (Se), and Strontium (Sr) from soil alone, coal fly ash alone, and soil-coal fly ash mixtures, were studied at a pH range of 2–14 via pH-dependent leaching tests. Seven different types of soils and coal fly ashes were tested. Results of this study indicated that Ca, Cd, Mg, and Sr showed cationic leaching pattern while As and Se generally follows an oxyanionic leaching pattern. On the other hand, leaching of Ba presented amphoteric-like leaching pattern but less pH-dependent. In spite of different types and composition of soil and coal fly ash investigated, the study reveals the similarity in leaching behavior as a function of pH for a given element from soil, coal fly ash, and soil-coal fly ash mixtures. The similarity is most likely due to similar controlling mechanisms (e.g., solubility, sorption, and solid-solution formation) and similar controlling factors (e.g., leachate pH and redox conditions). This offers the opportunity to transfer knowledge of coal fly ash that has been extensively characterized and studied to soil stabilized with coal fly ash. It is speculated that unburned carbon in off-specification coal fly ashes may provide sorption sites for Cd resulting in a reduction in concentration of these elements in leachate from soil-coal fly ash mixture. Class C fly ash provides sufficient CaO to initiate the pozzolanic reaction yielding hydrated cement products that oxyanions, including As and Se, can be incorporated into.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Composition and Structure of Block-Type Ferrospheres Isolated from Calcium-Rich Power Plant Ash

Polished sections of individual ferrospheres 30 to 40 μm in size, with single-block and blocky structures and a variable glass phase content, have been studied using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer system. The results demonstrate that the single-block globules consist of sintered magnetite crystallites containing Al{sub 2}O{sub 3}, MgO, and CaO as impurities and are formed from the pyrite of the initial coal. Characteristically, the ferrospheres with a variable glass phase content differ in the composition of local areas on polished sections of the globules, which attests to inhomogeneity of the melt droplets they formed from. We have identified groups of globules whose overall composition, as well as the composition of their local areas, meet general equations for the interrelation between the concentrations of their components: SiO{sub 2} = f(FeO) and SiO{sub 2} = f(Al{sub 2}O{sub 3}). Comparison of the coefficients of the SiO{sub 2} = f(Al{sub 2}O{sub 3}) dependence for the globules with the silicate modulus (SiO{sub 2}/Al{sub 2}O{sub 3}) of the aluminosilicate mineral components of the coal indicates that the formation of this type of globules involves pyrite–anorthite or pyrite–albite associates containing quartz impurities. The composition of the spinel ferrite in the globules produced with the participation of anorthite comprises FeO, Al{sub 2}O{sub 3}, MgO, and CaO in concentrations of 85–96, 1.7–10, 0.1–1.8, and 0.3–2.8 wt %, respectively. In the albite-based globules, the respective concentrations are 81–92, 0.7–5.9, 1.0–5.7, and 2.2–5.6 wt %. The crystallite size and shape are determined by the size of the local melt areas where the total concentration of spinel-forming oxides exceeds 85 wt %.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Integration of Feedstock Assembly System and Cellulosic Ethanol Conversion Models to Analyze Bioenergy System Performance

Research barriers continue to exist in all phases of the emerging cellulosic ethanol biorefining industry. These barriers include the identification and development of a sustainable and abundant biomass feedstock, the assembly of viable assembly systems formatting the feedstock and moving it from the field (e.g., the forest) to the biorefinery, and improving conversion technologies. Each of these phases of cellulosic ethanol production are fundamentally connected, but computational tools used to support and inform analysis within each phase remain largely disparate. This paper discusses the integration of a feedstock assembly system modeling toolkit and an Aspen Plus® conversion process model. Many important biomass feedstock characteristics, such as composition, moisture, particle size and distribution, ash content, etc. are impacted and most effectively managed within the assembly system, but generally come at an economic cost. This integration of the assembly system and the conversion process modeling tools will facilitate a seamless investigation of the assembly system conversion process interface. Through the integrated framework, the user can design the assembly system for a particular biorefinery by specifying location, feedstock, equipment, and unit operation specifications. The assembly system modeling toolkit then provides economic valuation, and detailed biomass feedstock composition and formatting information. This data is seamlessly and dynamically used to run the Aspen Plus® conversion process model. The model can then be used to investigate the design of systems for cellulosic ethanol production from field to final product.

09 BIOMASS FUELS↗
DOE OSTI2011

Utilization of municipal solid waste incineration fly ash for sulfoaluminate cement clinker production

Highlights: > The replacement can be taken up to 30% of MSWI fly ash in the raw mix. > The novelty compositional parameters were defined, their optimum values were determined. > Expansive property of SAC is strongly depended on gypsum content. > Three leaching test methods are used to assess the environmental impact. - Abstract: The feasibility of partially substituting raw materials with municipal solid waste incineration (MSWI) fly ash in sulfoaluminate cement (SAC) clinker production was investigated by X-ray diffraction (XRD), compressive strength and free expansion ratio testing. Three different leaching tests were used to assess the environmental impact of the produced material. Experimental results show that the replacement of MSWI fly ash could be taken up to 30% in the raw mixes. The good quality SAC clinkers are obtained by controlling the compositional parameters at alkalinity modulus (C{sub m}) around 1.05, alumina-sulfur ratio (P) around 2.5, alumina-silica ratio (N) around 2.0{approx}3.0 and firing the raw mixes at 1250 deg. C for 2 h. The compressive strengths of SAC are high in early age while that develop slowly in later age. Results also show that the expansive properties of SAC are strongly depended on the gypsum content. Leaching studies of toxic elements in the hydrated SAC-based system reveal that all the investigated elements are well bounded in the clinker minerals or immobilized by the hydration products. Although some limited positive results indicate that the SAC prepared from MSWI fly ash would present no immediate thread to the environment, the long-term toxicity leaching behavior needs to be further studied.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Carbonaceous Material Properties and Their Interactions with Slag During Electric Arc Furnace Steelmaking

The state of the interface between slag and carbon determines the slag foaming behavior and thus the effectiveness of carbon in electric arc furnace (EAF) steelmaking. This paper explores the interaction between synthetic slag and carbonaceous materials derived from various sources, including bio-char produced by two different technologies, graphite, coke, and char from tire pyrolysis. Different interfacial phenomena were found between slag and the carbonaceous materials examined. The interactions between bio-char and slag are found to be poor in comparison with other carbonaceous materials. Carbonaceous materials were characterized in terms of their chemical composition and the results obtained suggested that interfacial phenomena were not dominated by ash in the carbonaceous material. The effects of carbon crystalline structure on interaction with slag were evaluated by Raman spectroscopy and X-ray diffraction. Surface properties of the samples were evaluated using scanning electron microscopy, and surface morphology was identified as the principal factor affecting the interaction of slag on carbonaceous particles. The smooth surface of bio-char results in reduced slag foaming. This finding forms the basis for future research on the production of bio-char to be used as a slag foaming agent in EAF steelmaking.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

Ceramic thermal barrier coatings (TBCs) used in gas-turbine engines afford higher operating temperatures, resulting in enhanced efficiencies and performance. However, in the case of syngas-fired engines, fly ash particulate impurities that may be present in syngas can melt on the hotter TBC surfaces and form glassy deposits. These deposits can penetrate the TBCs leading to their failure. In experiments using lignite fly ash to simulate these conditions we show that conventional TBCs of composition 93wt% ZrO 2 + 7wt% Y 2 O 3 (7YSZ) fabricated using the air plasma spray (APS) process are completely destroyed by the molten fly ash. The molten fly ash is found to penetrate the full thickness of the TBC. The mechanisms by which this occurs appear to be similar to those observed in degradation of 7YSZ TBCs by molten calcium-magnesium-aluminosilicate (CMAS) sand and by molten volcanic ash in aircraft engines. In contrast, APS TBCs of Gd 2 Zr 2 O 7 composition are highly resistant to attack by molten lignite fly ash under identical conditions, where the molten ash penetrates ~25% of TBC thickness. This damage mitigation appears to be due to the formation of an impervious, stable crystalline layer at the fly ash/Gd 2 Zr 2 O 7 TBC interface arresting the penetrating molten-fly-ash front. Additionally, these TBCs were tested using a rig with thermal gradient and simultaneous accumulation of ash. Modeling using an established mechanics model has been performed to illustrate the modes of delamination, as well as further opportunities to optimize coating microstructure. Transfer of the technology was developed in this program to all interested parties.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2024

Coal Ash Beneficial Use at Savannah River Site

The Savannah River Site (SRS) has over 1.4 million cubic meters of coal ash and coal fines left over from coal-burning power plants that operated on site. Currently, the coal ash must be disposed of in an approved landfill or the coal ash-containing basins must be closed in place (i.e. consolidation, appropriate cover and liner system). Potential beneficial uses of the coal ash include geotechnical fill, such as backfill needed in the closure cap of the Z-area Saltstone Disposal Units (SDU), and use in cementitious material applications like thermal beneficiation or cement kiln feed, thereby reducing the environmental footprint of SRS. In this study, samples of coal ash from SRS were obtained and characterized for chemical and physical properties. Coal ash samples did not leach sulfates or heavy metals, so the coal ash is a candidate for geotechnical fill use. The samples also did not increase the acidity of the leachate during leaching tests, so it would not be detrimental to use as geotechnical fill near cementitious materials. The composition and energy potential of the coal ash makes it favorable for use as feed for external/off-site cement kilns or thermal beneficiation plants

01 COAL, LIGNITE, AND PEAT↗
NASA NTRS1993

JSC-1: A new lunar regolith simulant

Simulants of lunar rocks and soils with appropriate properties, although difficult to produce in some cases, will be essential to meeting the system requirements for lunar exploration. In order to address this need a new lunar regolith simulant, JSC-1, has been developed. JSC-1 is a glass-rich basaltic ash which approximates the bulk chemical composition and mineralogy of some lunar soils. It has been ground to produce a gain size distribution approximating that of lunar regolith samples. The simulant is available in large quantities (greater than 2000 lb; 907 kg). JSC-1 was produced specifically for large- and medium-scale engineering studies in support of future human activities on the Moon. Such studies include material handling, construction, excavation, and transportation. The simulant is also appropriate for research on dust control and spacesuit durability. JSC-1 can be used as a chemical or mineralogical analog to some lunar soils for resource studies such as oxygen or metal production, sintering, and radiation shielding.

Mckay, David S.↗
DOE OSTI2013

Design Study of an Incinerator Ash Conveyor Counting System - 13323

A design study has been performed for a system that should measure the Cs-137 activity in ash from an incinerator. Radioactive ash, expected to consist of both Cs-134 and Cs-137, will be transported on a conveyor belt at 0.1 m/s. The objective of the counting system is to determine the Cs-137 activity and direct the ash to the correct stream after a diverter. The decision levels are ranging from 8000 to 400000 Bq/kg and the decision error should be as low as possible. The decision error depends on the total measurement uncertainty which depends on the counting statistics and the uncertainty in the efficiency of the geometry. For the low activity decision it is necessary to know the efficiency to be able to determine if the signal from the Cs-137 is above the minimum detectable activity and that it generates enough counts to reach the desired precision. For the higher activity decision the uncertainty of the efficiency needs to be understood to minimize decision errors. The total efficiency of the detector is needed to be able to determine if the detector will be able operate at the count rate at the highest expected activity. The design study that is presented in this paper describes how the objectives of the monitoring systems were obtained, the choice of detector was made and how ISOCS (In Situ Object Counting System) mathematical modeling was used to calculate the efficiency. The ISOCS uncertainty estimator (IUE) was used to determine which parameters of the ash was important to know accurately in order to minimize the uncertainty of the efficiency. The examined parameters include the height of the ash on the conveyor belt, the matrix composition and density and relative efficiency of the detector. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers

Highlights: • The particle size of bottom ash influenced the acoustic behavior of the barrier. • The best sound absorption coefficients were measured for larger particle sizes. • The maximum noise absorption is displaced to lower frequencies for higher thickness. • A noise barrier was designed with better properties than commercial products. • Recycling products from bottom ash no present leaching and radioactivity problems. - Abstract: The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Nano-modification to improve the ductility of cementitious composites

Effect of nano-sized mineral additions on ductility of engineered cementitious composites (ECC) containing high volumes of fly ash was investigated at different hydration degrees. Various properties of ECC mixtures with different mineral additions were compared in terms of microstructural properties of matrix, fiber-matrix interface, and fiber surface to assess improvements in ductility. Microstructural characterization was made by measuring pore size distributions through mercury intrusion porosimetry (MIP). Hydration characteristics were assessed using thermogravimetric analysis/differential thermal analysis (TGA/DTA), and fiber-matrix interface and fiber surface characteristics were assessed using scanning electron microscopy (SEM) through a period of 90 days. Moreover, compressive and flexural strength developments were monitored for the same period. Test results confirmed that mineral additions could significantly improve both flexural strength and ductility of ECC, especially at early ages. Cheaper Nano-CaCO{sub 3} was more effective compared to nano-silica. However, the crystal structure of CaCO{sub 3} played a very important role in the range of expected improvements.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Thermal Shock-resistant Cement

We studied the effectiveness of sodium silicate-activated Class F fly ash in improving the thermal shock resistance and in extending the onset of hydration of Secar #80 refractory cement. When the dry mix cement, consisting of Secar #80, Class F fly ash, and sodium silicate, came in contact with water, NaOH derived from the dissolution of sodium silicate preferentially reacted with Class F fly ash, rather than the #80, to dissociate silicate anions from Class F fly ash. Then, these dissociated silicate ions delayed significantly the hydration of #80 possessing a rapid setting behavior. We undertook a multiple heating -water cooling quenching-cycle test to evaluate the cement’s resistance to thermal shock. In one cycle, we heated the 200°C-autoclaved cement at 500°C for 24 hours, and then the heated cement was rapidly immersed in water at 25°C. This cycle was repeated five times. The phase composition of the autoclaved #80/Class F fly ash blend cements comprised four crystalline hydration products, boehmite, katoite, hydrogrossular, and hydroxysodalite, responsible for strengthening cement. After a test of 5- cycle heat-water quenching, we observed three crystalline phase-transformations in this autoclaved cement: boehmite → γ-Al 2 O 3 , katoite → calcite, and hydroxysodalite → carbonated sodalite. Among those, the hydroxysodalite → carbonated sodalite transformation not only played a pivotal role in densifying the cementitious structure and in sustaining the original compressive strength developed after autoclaving, but also offered an improved resistance of the #80 cement to thermal shock. In contrast, autoclaved Class G well cement with and without Class F fly ash and quartz flour failed this cycle test, generating multiple cracks in the cement. The major reason for such impairment was the hydration of lime derived from the dehydroxylation of portlandite formed in the autoclaved cement, causing its volume to expand.

15 GEOTHERMAL ENERGY↗