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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Effects of aqueous uranyl speciation on the kinetics of microbial uranium reduction

The ability to predict the success of the microbial reduction of soluble U(VI) to highly insoluble U(IV) as an in situ bioremediation strategy is complicated by the wide range of geochemical conditions at contaminated sites and the strong influence of aqueous uranyl speciation on the bioavailability and toxicity of U(VI) to metal-reducing bacteria. In order to determine the effects of aqueous uranyl speciation on uranium bioreduction kinetics, incubations and viability assays with Shewanella putrefaciens strain 200 were conducted over a range of pH and dissolved inorganic carbon (DIC), Ca 2+ , and Mg 2+ concentrations. A speciation-dependent kinetic model was developed to reproduce the observed time series of total dissolved uranium concentration over the range of geochemical conditions tested. The kinetic model yielded the highest rate constant for the reduction of uranyl non-carbonate species (i.e., the ‘free’ hydrated uranyl ion, uranyl hydroxides, and other minor uranyl complexes), indicating that they represent the most readily reducible fraction of U(VI) despite being the least abundant uranyl species in solution. In the presence of DIC, Ca 2+ , and Mg 2+ is suppressed during the formation of more bioavailable uranyl non-carbonate species and resulted in slower bioreduction rates. At high concentrations of bioavailable U(VI), however, uranium toxicity to S. putrefaciens inhibited bioreduction, and viability assays confirmed that the concentration of non-carbonate uranyl species best predicts the degree of toxicity. The effect of uranium toxicity was accounted for by incorporating the free ion activity model of metal toxicity into the bioreduction rate law. These results demonstrate that, in the absence of competing terminal electron acceptors, uranium bioreduction kinetics can be predicted over a wide range of geochemical conditions based on the bioavailability and toxicity imparted on U(VI) by solution composition. Finally, these findings also imply that the concentration of uranyl non-carbonate species, despite being extremely low, is a determining factor controlling uranium bioreduction at contaminated sites.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Full-dimensional quantum studies of vibrational energy transfer dynamics between H 2 O and Ar: theory assessing experiment

In this work we report the first full-dimensional quantum mechanical calculations of the ro-vibrational inelastic scattering dynamics between water molecules and argon atoms on an accurate potential energy surface, using a recently developed time-independent quantum method based on the close-coupling approach. The state-to-state integral cross-sections and rate coefficients show strong observance of gap laws. The calculated thermal rate coefficients for the relaxation of the stretching fundamental states of H 2 O are in good agreement with experimental values, while those for the bending overtone state are approximately five times smaller than the values extracted through a previous kinetic modeling of fluorescence decay data. Our state-specific quantum scattering results suggest the need to reassess the kinetic modeling of the experimental data. This work advanced our understanding of the quantum dynamics of vibrationally inelastic energy transfer processes involving polyatomic molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution using rice husk-based activated carbon

An attempt was made to investigate the potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Rice husk-based activated carbon was prepared via treatment of rice husk with NaOH followed by the carbonization process at 400°C for 2 hours. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). These samples were also analyzed for their carbon, hydrogen, nitrogen, oxygen and silica contents using CHN elemental analyzer and FESEM/EDX. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were 255 m{sup 2}/g and 0.17 cm{sup 2}/g, respectively. The adsorption studies for the removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution were carried out at a fixed initial concentration of metal ion (150 ppm) with variation amount of adsorbent (rice husk-based activated carbon) as a function of varied contact time at room temperature. The concentration of each metal ion was analyzed using atomic absorption spectrophotometer (AAS). The results obtained from adsorption studies indicate the potential of rice husk as an economically promising precursor for the preparation of activated carbon for removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Isotherm and kinetic model analyses suggested that the experimental data of adsorption studies fitted well with Langmuir, Freundlich and second-order kinetic models.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Effects of Exhaust Gas Recirculation (EGR) on Turbulent Combustion and Emissions in Advanced Gas Turbine Combustors with High-Hydrogen-Content (HHC) Fuels (Final Report)

This Final Report documents the entire four years of the Cooperative Agreement DE-FE0011822, from October 1, 2013 through September 30, 2017, that was competitively awarded under Funding Opportunity Announcement DE-FOA-0000795 in support of the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) University Turbine Systems Research (UTSR) Program. Under the UTSR Program, DOE typically issues Funding Opportunity Announcement (FOA) solicitations every 1-2 years so that U.S. colleges/universities may propose research & development (R&D) projects in specific technical topic areas (e.g., combustion, aerodynamics/heat transfer, advanced materials) that have been identified as both scientifically and industrially relevant to the gas turbine industry. The primary objectives of this Purdue University project (in collaboration with Princeton University through a sub-award) was to develop experimental methods, kinetic models, and numerical tools to help quantify and predict the impact of exhaust gas recirculation (EGR) on NOx and CO emissions, combustion kinetics, radiation heat transfer, turbulent combustion, and combustion instabilities for natural gas and high hydrogen content (HHC) fuels by using laminar and turbulent flow reactors and gas turbine combustors operating at high temperatures and pressures. This project has obtained detailed data for improving chemical kinetic models to study EGR effects and provide insight into the effects of EGR on flame speeds and turbulent flame structure, as well as assessing the impact of EGR on emissions in a high-pressure combustion test rig. The project was divided into six primary tasks: 1) Project Management and Program Planning; 2) Flow Reactor Investigation of EGR Chemical Kinetics; 3) Combustion Bomb Investigation of EGR Effects on Flame Speed; 4) Investigation of EGR Effects on Turbulent Flame Structure in Reactor-Assisted Turbulent Slot (RATS) Burner; 5) Investigation of EGR Effects in Purdue Staged Combustion Test Rig; and 6) Development and Validation of a Large Eddy Simulation (LES) Tool for Gas Turbine Combustion and Emission Modeling using HHC Fuels. Details on the execution and results of each of these tasks are provided in the main report. To assist the reader, each task is described in a chapter-like format with its own separate listing of tables, figures, and references so that the results of each task/subtask (i.e., technical sections covering various experiments and modeling work focused on a specific area) can be quickly obtained while also getting an overall feel of the project execution. This chapter-like format also allows for acknowledgement of support from other programs relative to specific tasks. In this manner, the reader can more conveniently digest the R&D results in the various task/subtask sections that may be of most interest to the reader. In addition to this Final Report, the Purdue/Princeton team was able to publish 7 journal articles and provide 7 presentations at national scientific meetings/conferences to disseminate results. A listing of these journal articles and presentations is provided at the end of this report

03 NATURAL GAS↗
DOE OSTI2022

Verification of a fully kinetic ion model for electromagnetic simulations of high-frequency waves in toroidal geometry

For the research of high-frequency electromagnetic waves in tokamaks, an electromagnetic simulation model, in which the ion dynamics is described by a six-dimensional Vlasov equation and the electron dynamics is described by a drift kinetic equation, is formulated and implemented in the global gyrokinetic toroidal code (GTC). Analytic dispersion relations are derived in reduced systems and compared with various theories to verify the model. Linear simulations of a generalized ion Bernstein wave and ion cyclotron emission are verified by comparing the GTC simulation results with analytic dispersion relation theory and magnetoacoustic cyclotron instability theory, respectively, in cylindrical geometry.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

From Rate Measurements to Mechanistic Data for Condensed Matter Reactions: A Case Study Using the Crystallization of [Zn(OH 2 ) 6 ][ZnCl 4 ]

The kinetics of crystallization of the R = 3 hydrate of zinc chloride, [Zn(OH 2 ) 6 ][ZnCl 4 ], is measured by time-resolved synchrotron x-ray diffraction, time-resolved neutron diffraction, and by differential scanning calorimetry. It is shown that analysis of the rate data using the classic Kolmogorov, Johnson, Mehl, Avrami (KJMA) kinetic model affords radically different rate constants for equivalent reaction conditions. Reintroducing the amount of sample measured by each method into the kinetic model, using our recently developed modified-KJMA model (M-KJMA), it is shown that each of these diverse rate measurement techniques can give the intrinsic, material specific rate constant, the velocity of the phase boundary, v pb . These data are then compared to the velocity of the crystallization front directly measured optically. The time-resolved diffraction methods uniquely monitor the loss of the liquid reactant and formation of the crystalline product demonstrating that the crystallization of this hydrate phase proceeds through no intermediate phases. The temperature dependent v pb data are then well fit to transition zone theory to extract activation parameters. These demonstrate that the rate-limiting component to this crystallization reaction is the ordering of the waters (or protons) of hydration into restricted positions of the crystalline lattice resulting in large negative entropy of activation.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Optimizing ensemble NV − spin properties of fluorescent diamond microparticles by systematic low pressure high temperature annealing

Low pressure high temperature annealing is a means for driving nitrogen and defect diffusion in diamond to reduce internal lattice damage without the need for technically complicated high-pressure cells. Herein, we perform a systematic time (5, 15, and 30 min) and temperature (1200 °C–1800 °C) study of effects of low-pressure high temperature annealing on photoluminescence, spin concentrations, and spin relaxation properties of NV centers in ca. 3 μm synthetic type 1b diamond particles. Annealing in the temperature range of ca. 1400 °C–1700 °C for even 5 min leads to a higher optically detected magnetic resonance contrast as compared to standard annealing at 900 °C for 2 h. Particles annealed at 1700 °C for 5 min exhibit a contrast close to about 13% as compared to about 9% for those annealed at 900 °C for 2 h. A reduction in the zero-field splitting strain parameter from E ≈ 4.5 MHz to ≈ 2.5 MHz and spectral linewidth from Δν ≈ 7 MHz to ≈ 4 MHz are observed even after 5 min annealing at 1700 °C. Improvements in these spectral parameters resulted in a roughly 2-fold reduction in the noise level of temperature monitoring experiment utilizing an ensemble of NV centers in the particles. Annealing in the temperature range of 1600 °C for 15 or 30 min or 1700 °C for 5 min resulted in NV T 1 relaxation times approaching ca. 5 ms typically observed for bulk diamond. Quantitative electron paramagnetic resonance (EPR) allowed for estimations of thermal activation energies of paramagnetic center annihilation. Monitoring the primary defect concentration (P1 and other defects with half integer spins) and utilizing second order kinetic modeling, an activation energy of 3.63 ± 0.28 eV was estimated. Alternatively, using the NV half field EPR signal and first order kinetic modeling, a similar activation energy 3.89 ± 0.29 eV was estimated.

NV centers↗
DOE OSTI2021

Embedded Error Bayesian Calibration of Thermal Decomposition of Organic Materials

Organic materials are an attractive choice for structural components due to their light weight and versatility. However, because they decompose at low temperatures relative to tradiational materials they pose a safety risk due to fire and loss of structural integrity. To quantify this risk, analysts use chemical kinetics models to describe the material pyrolysis and oxidation using thermogravimetric analysis. This process requires the calibration of many model parameters to closely match experimental data. Previous efforts in this field have largely been limited to finding a single best-fit set of parameters even though the experimental data may be very noisy. Furthermore the chemical kinetics models are often simplified representations of the true de- composition process. The simplification induces model-form errors that the fitting process cannot capture. In this work we propose a methodology for calibrating decomposition models to thermogravimetric analysis data that accounts for uncertainty in the model-form and experimental data simultaneously. The methodology is applied to the decomposition of a carbon fiber epoxy composite with a three-stage reaction network and Arrhenius kinetics. The results show a good overlap between the model predictions and thermogravimetric analysis data. Uncertainty bounds capture devia- tions of the model from the data. The calibrated parameter distributions are also presented. In conclusion, the distributions may be used in forward propagation of uncertainty in models that leverage this material.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Modeling and Manipulating Phenylpropanoid Pathway Flux for Bioenergy

We have made important strides toward our project goals over the past five years. First, we developed and published a novel isotopic feeding system to investigate metabolic fluxes of the lignin biosynthesis. Next, we have developed and published a kinetic model of the phenylpropanoid pathway. As an extension of that work, we developed a multilayer kinetic model of lignin biosynthesis. Next we conducted a systematic transcriptome and metabolome analysis for phenylpropanoid metabolism. Finally, we have identified three strategies that enhance the accumulation of 2-phenylethanol in plants.

09 BIOMASS FUELS↗
DOE OSTI2017

The kinetics of polyurethane structural foam formation: Foaming and polymerization

We are developing kinetic models to understand the manufacturing of polymeric foams, which evolve from low viscosity Newtonian liquids, to bubbly liquids, finally producing solid foam. Closed-form kinetics are formulated and parameterized for PMDI-10, a fast curing polyurethane, including polymerization and foaming. PMDI- 10 is chemically blown, where water and isocyanate react to form carbon dioxide. The isocyanate reacts with polyol in a competing reaction, producing polymer. Our approach is unique, though it builds on our previous work and the polymerization literature. This kinetic model follows a simplified mathematical formalism that decouples foaming and curing, including an evolving glass transition temperature to represent vitrification. This approach is based on IR, DSC, and volume evolution data, where we observed that the isocyanate is always in excess and does not affect the kinetics. Finally, the kinetics are suitable for implementation into a computational fluid dynamics framework, which will be explored in subsequent papers.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Catalyst and reactor design considerations for selective production of acids by oxidative cleavage of alkenes and unsaturated fatty acids with H 2 O 2

Oxidative cleavage of alkenes and unsaturated fatty acids with hydrogen peroxide gives an efficient and sustainable process to obtain mono- and di-acids for polymers and lubricants with fewer safety risks and less environmental impact than processes that utilize ozone or other inorganic oxidizers (e.g., permanganate, dichromate, etc.). Guided by insight into the mechanisms for competing reaction pathways (i.e., epoxidation of alkene on W–(η 2 -O 2 ) complexes vs. H 2 O 2 decomposition) and the apparent kinetics derived from kinetic experiments, here, we postulate that W-based heterogeneous catalysts can provide high performance and stable operations at low H 2 O 2 concentrations. Semi-batch reactors with continuous introduction of H 2 O 2 solutions offer the means to maintain low H 2 O 2 concentrations while providing sufficient quantities of H 2 O 2 to satisfy the reaction stoichiometry. We derived simple kinetic model equations for the epoxidation, ring-opening, oxidative cleavage, and oxidation steps and fit theses equations to batch experimental data to obtain kinetic parameters. Furthermore, this kinetic model describes the concentration profiles of reactant, oxidant, and products well as shown by agreement with experimental data. Further predictions of the optimal H 2 O 2 feed rate for semi-batch operation utilized by the proposed rate expressions and the reactor design equations suggest that low H 2 O 2 feed rate increases selectivity towards oxidative cleavage products and selective use of H 2 O 2 for oxidative cleavage pathway. Comparisons of oxidative cleavage of 4-octene in batch and semi-batch reactors show that semibatch reactors with optimized molar feed rates of H 2 O 2 increased oxidative cleavage product selectivities (76% to 99%; with an increase in butyric acid selectivity from 1% to 55%) and H 2 O 2 selectivity (3% to 30%). In addition, semibatch reaction conditions used avoid H 2 O 2 -mediated dissolution of W-atoms from the catalyst. Analysis of these findings suggest that solid oxide catalysts will be effective for continuous oxidative cleavage reactions if deployed within fixed-bed reactors that allow for distributed introduction of reactants and therefore low in situ concentrations of H 2 O 2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Data for Catalyst and Reactor Design Considerations for Selective Production of Acids by Oxidative Cleavage of Alkenes with H2O2

Oxidative cleavage of alkenes and unsaturated fatty acids with hydrogen peroxide gives an efficient and sustainable process to obtain mono- and di-acids for polymers and lubricants with fewer safety risks and less environmental impact than processes that utilize ozone or other inorganic oxidizers (e.g., permanganate, dichromate, etc.). Guided by insight into the mechanisms for competing reaction pathways (i.e., epoxidation of alkene on W–(η2-O2) complexes vs. H2O2 decomposition) and the apparent kinetics derived from kinetic experiments, here, we postulate that W-based heterogeneous catalysts can provide high performance and stable operations at low H2O2 concentrations. Semi-batch reactors with continuous introduction of H2O2 solutions offer the means to maintain low H2O2 concentrations while providing sufficient quantities of H2O2 to satisfy the reaction stoichiometry. We derived simple kinetic model equations for the epoxidation, ring-opening, oxidative cleavage, and oxidation steps and fit theses equations to batch experimental data to obtain kinetic parameters. This kinetic model describes the concentration profiles of reactant, oxidant, and products well as shown by agreement with experimental data. Further predictions of the optimal H2O2 feed rate for semi-batch operation utilized by the proposed rate expressions and the reactor design equations suggest that low H2O2 feed rate increases selectivity towards oxidative cleavage products and selective use of H2O2 for oxidative cleavage pathway. Comparisons of oxidative cleavage of 4-octene in batch and semi-batch reactors show that semi-batch reactors with optimized molar feed rates of H2O2 increased oxidative cleavage product selectivities (76% to 99%; with an increase in butyric acid selectivity from 1% to 55%) and H2O2 selectivity (3% to 30%). In addition, semi-batch reaction conditions used avoid H2O2-mediated dissolution of W-atoms from the catalyst. Analysis of these findings suggest that solid oxide catalysts will be effective for continuous oxidative cleavage reactions if deployed within fixed-bed reactors that allow for distributed introduction of reactants and therefore low in situ concentrations of H2O2.

Catalysis↗
DOE OSTI2019

Performance efficiency and kinetic studies of water purification using ZnO and MgO nanoparticles for potassium permanganate

Zinc oxide (ZnO) and Magnesium oxide (MgO) nanoparticles (NPs) have been synthesized by solid–solid reaction technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) were used to investigate the structural properties of ZnO and MgO NPs. XRD indicates that structural of ZnO NPs has a hexagonal structure with space group P63mc. On the other hand, MgO NPs is cubic structure with space group Fm 3-bar m. The photocatalytic efficiency of both ZnO and MgO NPs as a catalyst was illustrated by studying the extreme quantity of potassium permanganate (KMnO{sub 4}) degradation rate in wastewater. KMnO{sub 4} achieved 17% and 25% degradation rate in 180 min for ZnO and MgO NPs, respectively. The experimental data were examined by the kinetic models of pseudo-first and second order as well as intra-particle diffusion. The obtained data is expressed well by the second-order kinetic model for both NPs. Moreover, according to the experimental results, MgO NPs has high-performance water purification as a comparison of ZnO NPs effect.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Microstructural Characterization of Alloy 709 Plate Materials with Additional Heat Treatment Protocol

This report provides the results on microstructural characterization of the first commercial heat of Alloy 709 plate material which has undergone additional heat treatment protocol. The report is a Level 4 deliverable in FY19 (M4AT-19AN020502012), under the Work Package AT19AN0205201, “A709 Development – ANL.” The study involves thermodynamic-kinetic modeling, heat treating of materials, microhardness testing, x-ray diffraction (XRD) study, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) study. Through thermodynamic-kinetic modeling, it is determined that after an 1100°C solutionizing treatment, heat treating of Alloy 709 at 775°C for 10 hours or at 900°C for 10 hours are candidate recipes for promoting desired microstructural features. Both heat treatments were executed on small samples of the AOD-1100°C condition of the commercial heat of Alloy 709. Micro-hardness tests showed that both treatments increases the hardness of the material. XRD showed that both treatments brings out M23C6 and MX phases, though the 775°C/10h-treatment has more profound effect. The TEM study revealed that similar for both conditions, M23C6 precipitated on grain boundaries and within grain interior. In contrast, after the 775°C/10h treatment, the dislocations are decorated with MX nano particles, while after the 900°C/10h treatment, most of the dislocations are free of MX particles. It is thus determined that the 775°C/10h treatment has a better potential to provide enhanced creep properties by pinning the dislocations with nano particles. Following this study, the 775°C/10h treatment was carried out on a large ESR-1100°C plate at Idaho National Laboratory. Hardness testing and microstructural characterization were performed and compared between the two materials being heated treated under the same protocol. The implication on mechanical properties was briefly discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Drift kinetic effects on the plasma response in high beta spherical tokamak experiments

High $\beta$ plasma response to the rotating n=1 external magnetic perturbations is numerically studied and compared with National Spherical Torus eXperiment (NSTX). The hybrid magnetohydrodynamic(MHD)-kinetic modeling shows the drift kinetic effects are important to resolve the disagreement of plasma response between the ideal MHD prediction and the NSTX experimental observation when plasma pressure reaches and exceeds the no-wall limit [F. Troyon et al., Plasma Phys. Control. Fusion \textbf{26}, 209 (1984)]. Since the external rotating fields and high plasma rotation are presented in NSTX experiments, the importance of resistive wall effect and plasma rotation on determining the plasma response is also identified, where the resistive wall suppresses the plasma response through the wall eddy current. The inertial energy, due to plasma rotation, destabilizes the plasma. The complexity of plasma response, in this study, indicates that MHD modeling, including comprehensive physics e.g. the drift kinetic effects, resistive wall and plasma rotation, is essential to reliably predict the plasma behavior in high beta spherical tokamak device.

Tokamak↗