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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Electric-charge-dependent directed flow splitting of produced quarks in Au+Au collisions

We report directed flow (v 1 ) of multistrange baryons ($Ξ$ and Ω) and improved v 1 data for K – ,$\overline{p}$, $\overline{Λ}$, and ϕ in Au+Au collisions at $\sqrt{s_{NN}}$ = 27 and 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). We focus on particles whose constituent quarks are not transported from the incoming nuclei but instead are produced in the collisions. At intermediate impact parameters, we examine quark coalescence behavior for particle combinations with identical quark content, and search for any departure from this behavior (“splitting”) for combinations having non-identical quark content. Under the assumption of quark coalescence for produced quarks, the splitting strength appears to increase with the electric charge difference of the constituent quarks in the combinations, consistent with electromagnetic effect expectations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Modern deep neural networks for Direct Normal Irradiance forecasting: A classification approach

The escalating energy demand and the adverse environmental impacts of fossil-fuel use necessitate a shift towards cleaner and renewable alternatives. Concentrated Solar Power (CSP) technology emerges as a promising solution, offering a carbon-free alternative for power generation. The efficiency and profitability of CSP depend on the Direct Normal Irradiance (DNI) component of solar radiation; hence, accurate DNI forecasting can help optimize CSP plants’ operations and performance. The unpredictable nature of weather phenomena, particularly cloud cover, introduces uncertainty into DNI projections. Existing DNI forecasting models use meteorological factors, which are both challenging to estimate numerically over short prediction windows and expensive to model through data at a sufficiently high spatial and temporal resolution. This research addresses the challenge by presenting a novel approach that formulates DNI prediction as a multi-class classification problem, departing from conventional regression-based methods. The primary objective of this classification framework is to identify optimal periods aligning with specific operational thresholds for CSP plants, contributing to enhanced dispatch optimization strategies. We model the DNI classification problem using four advanced deep neural networks – rectified linear unit (ReLU) networks, 1D residual networks (ResNets), bidirectional long short-term memory (BiLSTM) networks, and transformers – achieving accuracies up to 93.5% without requiring meteorological parameters.

14 SOLAR ENERGY↗
DOE OSTI2020

Turbulence/flame/wall interactions in non-premixed inclined slot-jet flames impinging at a wall using direct numerical simulation

In this paper, three-dimensional turbulent non-premixed oblique slot-jet flames impinging at a wall were investigated using direct numerical simulation (DNS). Two cases are considered with the Damköhler number (Da) of case A being twice that of case B. A 17 species and 73-step mechanism for methane combustion was employed in the simulations. It was found that flame extinction in case B is more prominent compared to case A. Reignition in the lower branch of combustion for case A occurs when the scalar dissipation rate relaxes, while no reignition occurs in the lower branch for case B due to excessive scalar dissipation rate. A method was proposed to identify the flame quenching edges of turbulent non-premixed flames in wall-bounded flows based on the intersections of mixture fraction and OH mass fraction iso-surfaces. The flame/wall interactions were examined in terms of the quenching distance and the wall heat flux along the quenching edges. There is essentially no flame/wall interaction in case B due to the extinction caused by excessive turbulent mixing. In contrast, significant interactions between flames and the wall are observed in case A. The quenching distance is found to be negatively correlated with wall heat flux as previously reported in turbulent premixed flames. The influence of chemical reactions and wall on flow topologies was identified. The FS/U and FC/U topologies are found near flame edges, and the NNN/U topology appears when reignition occurs. The vortex-dominant topologies, FC/U and FS/S, play an increasingly important role as the jet turbulence develops.

42 ENGINEERING↗
DOE OSTI2021

Exposure, health effects, sensing, and remediation of the emerging PFAS contaminants – Scientific challenges and potential research directions

Per- and polyfluoroalkyl substances (PFAS) make up a large group of persistent anthropogenic chemicals which are difficult to degrade and/or destroy. PFAS are an emerging class of contaminants, but little is known about the long-term health effects related to exposure. In addition, technologies to identify levels of contamination in the environment and to remediate contaminated sites are currently inadequate. In this opinion-type discussion paper, a team of researchers from the University of Connecticut and the University at Albany discuss the scientific challenges in their specific but intertwined PFAS research areas, including rapid and low-cost detection, energy-saving remediation, the role of T helper cells in immunotoxicity, and the biochemical and molecular effects of PFAS among community residents with measurable PFAS concentrations. Potential research directions that may be employed to address those challenges and improve the understanding of sensing, remediation, exposure to, and health effects of PFAS are then presented. Here, we hope our account of emerging problems related to PFAS contamination will encourage a broad range of scientific experts to bring these research initiatives addressing PFAS into play on a national scale.

Challenges and research directions↗
DOE OSTI2020

Three-dimensional hierarchical nanoporous copper via direct ink writing and dealloying

Three-dimensional (3D) hierarchical nanoporous Cu (3DHNP-Cu) is synthesized using a combination of direct ink writing (DIW) based 3D printing, thermal sintering, and chemical dealloying of Mn–Cu alloys. Through tuning processing conditions such as ink composition and cooling rate (after sintering), with consideration of Mn loss during sintering, 3DHNP-Cu with fully bicontinuous nanostructures and negligible residual Mn can be produced after dealloying. The 3DHNP-Cu is comprised of structural features that span seven orders of magnitude, where DIW digitally controls macroscale porous features, thermal sintering and degradation of the binding polymer determines microscale porous features, and dealloying gives rise to nanoscale pores.

36 MATERIALS SCIENCE↗
DOE OSTI2023

High-resolution 3D strain and orientation mapping within a grain of a directed energy deposition laser additively manufactured superalloy

The industrialization of Laser Additive Manufacturing (LAM) is challenged by the undesirable microstructures and high residual stresses originating from the fast and complex solidification process. Non-destructive assessment of the mechanical performance controlling deformation patterning is therefore critical. Here, we use Dark Field X-ray Microscopy (DFXM) to map the 3D subsurface intragranular orientation and strain variations throughout a surface-breaking grain within a directed energy deposition nickel superalloy. DFXM results reveal a highly heterogenous 3D microstructure in terms of the local orientation and lattice strain. The grain comprises ≈ 5 μm-sized cells with alternating strain states, as high as 5 x10 -3 , and orientation differences <0.5°. The DFXM results are compared to Electron Backscatter Diffraction measurements of the same grain from its cut-off surface. Here, we discuss the microstructure developments during LAM, rationalising the development of the deformation patterning from the extreme thermal gradients during processing and the susceptibility for solute segregation.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Direct recycling and remanufacturing of anode scraps

With the rapid expansion of Li-ion battery production, significant amounts of electrode scraps that need to be recycled are being produced during cell manufacturing. Anode scrap that comprises critical materials such as graphite and valuable Cu should be recycled and reintegrated into the battery supply chain. This study reports a simple yet efficient water-based recovery process for delaminating anode films from Cu foils through the intercalation of water between the hydrophilic Cu foil and hydrophobic anode coating. Because of the absence of harsh chemicals, the recovered anode films and Cu foils are battery grade and free of damage in terms of physical and chemical properties. This study also demonstrates the reprocessing of those anode films into a new anode that exhibits electrochemical performance similar to that of the pristine anode. We report this environmentally friendly and cost-effective separation technique allows battery manufacturers to directly recycle and reuse their electrode scraps safely and effectively on-site.

25 ENERGY STORAGE↗
DOE OSTI2023

Techno-economic and environmental life cycle assessment of next-generation fiber-encapsulated nanoscale hybrid materials for direct air carbon capture

A techno-economic and environmental life cycle assessment was conducted for manufacturing two novel types of solid sorbents used for direct air CO 2 capture (DAC). One type of solid sorbent comprised Polyacrylonitrile (PAN)/Organopolysilizane (OPSZ)/nanoscale organic hybrid materials (NOHM)(, and the other comprised polymers of intrinsic microporosity (PIM)/NOHM. These solid sorbents were assumed to be manufactured via an unconventional route: electrospinning as fibers. Economic analyses revealed that manufacturing costs for a 0.73 MT/year capacity plant was $\$$831 and $\$$1398/kg of electrospun fiber in the case ofPAN/OPSZ/NOHM and PIM/NOHM, respectively. The costs were higher for PIM/NOHM owing to high raw material prices (Spirobisindane and tetrafluoroterephthalonitrile), that are used only in manufacturing PIM. Scaling up the plant capacity from 0.73 to 30 MT/year plant decreased the manufacturing cost by nearly half from $\$$831 to $\$$379 in the case of PAN/OPSZ/NOHM, depicting the economies of scale of effect. An LCA of both types of solid sorbent was performed using OpenLCA software, the Ecoinvent v 3.5 database, and the TRACI LCI assessment method. The Global Warming Potential (GWP) ofPAN/OPSZ/NOHM and PIM/NOHM was observed to be 151 × 10 -3 and 166 × 10 -3 kg CO 2 per kg CO 2 captured in the DAC plant, respectively. In conclusion, these GWP values were nearly five times as high as those observed for other solid sorbents existing in the literature such as PEI on silica gel, carbonate on silica, and carbonate on activated carbon owing to large amounts of electricity used in electrospinning unit operation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Investigation of high-pressure turbulent jets using direct numerical simulation

Direct numerical simulations of free round jets at a Reynolds number (Re D ) of 5000, based on jet diameter (D) and jet-exit bulk velocity (U e ), are performed to study jet turbulence characteristics at supercritical pressures. The jet consists of nitrogen (N 2 ) that is injected into N 2 at the same temperature. To understand turbulent mixing, a passive scalar is transported with the flow at unity Schmidt number. Two sets of inflow conditions that model jets issuing from either a smooth contraction nozzle (laminar inflow) or a long pipe nozzle (turbulent inflow) are considered. By changing one parameter at a time, the simulations examine the jet-flow sensitivity to the thermodynamic condition (characterized in terms of the compressibility factor ($Z$) and the normalized isothermal compressibility), inflow condition and ambient pressure (p ∞ ) spanning perfect- to real-gas conditions. The inflow affects flow statistics in the near field (containing the potential core closure and the transition region) as well as further downstream (containing fully developed flow with self-similar statistics) at both atmospheric and supercritical p ∞ . The sensitivity to inflow is larger in the transition region, where the laminar-inflow jets exhibit dominant coherent structures that produce higher mean strain rates and higher turbulent kinetic energy than in turbulent-inflow jets. Decreasing $Z$ at a fixed supercritical p ∞ enhances pressure and density fluctuations (non-dimensionalized by local mean pressure and density, respectively), but the effect on velocity fluctuations depends also on the local flow dynamics. When $Z$ is reduced, large mean strain rates in the transition region of laminar-inflow jets significantly enhance velocity fluctuations (non-dimensionalized by local mean velocity) and scalar mixing, whereas the effects are minimal in jets from turbulent inflow.

42 ENGINEERING↗
DOE OSTI2023

Radiocarbon analysis of soil microbial biomass via direct chloroform extraction

Microbial processing of soil organic matter is a significant driver of C cycling, yet we lack an understanding of what shapes the turnover of this large terrestrial pool. In part, this is due to limited options for accurately identifying the source of C assimilated by microbial communities. Laboratory incubations are the most common method for this; however, they can introduce artifacts due to sample disruption and processing and can take months to produce sufficient CO 2 for analysis. We present a biomass extraction method which allows for the direct 14 C analysis of microbial biomolecules and compare the results to laboratory incubations. In the upper 50 cm soil depths, the Δ 14 C from incubations was indistinguishable from that of extracted microbial biomass. Below 50 cm, the Δ 14 C of the biomass was more depleted than that of the incubations, either due to the stimulation of labile C decomposition in the incubations, the inclusion of biomolecules from non-living cells in the biomass extractions, or differences in C used for assimilation versus respiration. Our results suggest that measurement of Δ 14 C of microbial biomass extracts can be a useful alternative to soil incubations.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Carbonation of MgO Single Crystals: Implications for Direct Air Capture of CO 2

Direct air capture (DAC) may be feasible to remove carbon dioxide (CO 2 ) from the atmosphere at the gigaton scale, holding promise to become a major contributor to climate change mitigation. Mineral looping using magnesium oxide (MgO) is potentially an economical, efficient, and sustainable pathway to gigaton-scale DAC. The hydroxylation and carbonation of MgO determine the efficiency of the looping process, but their rates and mechanisms remain uncertain. Here, in this work, MgO single crystals were reacted in air or CO 2 at varying humidities and characterized by X-ray scattering, microscopy, and vibrational spectroscopy. Results show that the hydroxylation formed a brucite (Mg(OH) 2 )-like layer immediately after crystal cleaving. Concurrently, the carbonation formed hydrated magnesium carbonate phases, including barringtonite (MgCO 3 ·2H 2 O) and nesquehonite (MgCO 3 ·2H 2 O), in the layer. Rapid initial growth of the layer is also manifested in short-range bending/warping of nanocrystallites, resulting in multiple orientations of the same phases on the surface. The layer growth slowed down over time, indicating surface passivation. The formation of barringtonite and nesquehonite with 1:1 CO 3 /Mg ratio indicates an efficient carbonation when compared to other magnesium carbonate phases of lower ratio. Our results are essential for understanding surface passivation mechanisms and tackling the passivation issue of mineral looping DAC technology.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

CO 2 Sorption in Moisture Swing Anion Exchange Resins for Direct Air Capture: Experimental Isotherm Determination and Modeling

Moisture swing (MS) sorption is a promising direct air capture (DAC) technology to achieve negative CO 2 emissions and counter global warming. Here, in this study, MS CO 2 sorption in a model MS sorbent, IRA900, was investigated. IRA900 is a macroporous commercial strong-base anion exchange resin (AER) with quaternary ammonium functional groups. A rigorous CO 2 desorption process was developed to desorb all CO 2 from the sample and obtain CO 2 sorption isotherms as a function of relative humidity, CO 2 partial pressure, and temperature. CO 2 sorption increased with decreasing relative humidity, decreasing temperature, and increasing CO 2 partial pressure. Remarkably, the total CO 2 uptake from the sorption isotherms matched the ion exchange capacity (IEC) of the material, suggesting a stoichiometry of one CO 2 molecule reacting per active site. An isotherm model for CO 2 sorption starting with empty sorption sites (i.e., with the AER in the OH – form) described the experimental data well, supporting the hypothesis that the bicarbonate-loaded AER fully unloaded to the OH – state following rigorous CO 2 desorption. CO 2 sorption kinetics were studied, and carbon diffusion coefficients were estimated as a function of %RH and CO 2 partial pressure. Overall, this study provides a roadmap for the systematic evaluation of MS CO 2 DAC materials.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2026

Energy Emissions Accounting Methods Can Determine Whether Direct Air Capture with Storage Achieves Net Removal

The voluntary carbon market within the United States has expanded rapidly in recent years and enabled private companies and other organizations to provide revenue streams to carbon dioxide removal (CDR) technologies. For a CDR technology to participate in the voluntary carbon market (VCM), the emissions associated with constructing and operating the technology must be less than the CO 2 captured from the atmosphere. Assessing the extent to which this is true for direct air capture with storage (DACS), a relatively energy-intensive CDR technology, strongly depends on the accounting method used to assess the emissions intensity of purchased energy. We simulate the hourly weather-dependent operation of sorbent- and solvent-based DACS in California, Louisiana, Texas, and Wyoming, representing a wide range of local weather and electric and natural gas grid compositions. In all cases, the single most important emissions accounting decision is the method used to estimate the emissions intensity of purchased grid electricity, which varies the calculated net removal by −1049% to +108%. All other factors influencing net removal introduce a variation of at most ±14%. No electricity emissions accounting method is universally conservative across all scenarios, and none is objectively more accurate. High-spatiotemporal-resolution, high-quality, publicly available data sets and models for electricity emissions accounting do not currently exist and are urgently needed to enable standardization of emissions accounting methods to more accurately determine the true emissions impacts of DACS and other energy-intensive facilities.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Adsorption, Orientation, and Speciation of Amino Acids at Air–Aqueous Interfaces for the Direct Air Capture of CO 2

Amino acids make up a promising family of molecules capable of direct air capture (DAC) of CO 2 from the atmosphere. Under alkaline conditions, CO 2 reacts with the anionic form of an amino acid to produce carbamates and deactivated zwitterionic amino acids. The presence of the various species of amino acids and reactive intermediates can have a significant effect on DAC chemistry, the role of which is poorly understood. In this study, all-atom molecular dynamics (MD) based computational simulations and vibrational sum frequency generation (vSFG) spectroscopy studies were conducted to understand the role of competitive interactions at the air–aqueous interface in the context of DAC. We find that the presence of potassium bicarbonate ions, in combination with the anionic and zwitterionic forms of amino acids, induces concentration and charge gradients at the interface, generating a layered molecular arrangement that changes under pre- and post-DAC conditions. In parallel, an enhancement in the surface activity of both anionic and zwitterionic forms of amino acids is observed, which is attributed to enhanced interfacial stability and favorable intermolecular interactions between the adsorbed amino acids in their anionic and zwitterionic forms. The collective influence of these competitive interactions, along with the resulting interfacial heterogeneity, may in turn affect subsequent capture reactions and associated rates. Finally, these effects underscore the need to consider dynamic changes in interfacial chemical makeup to enhance DAC efficiency and to develop successful negative emission and storage technologies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Quaternary Ammonium-Functionalized Poly(Arylene Ether Sulfone) Random Copolymers for Direct Air Capture

Direct air capture (DAC) is a promising tool for reducing CO 2 concentrations in the atmosphere and fighting climate change. We synthesized a series of quaternary ammonium (QA) functionalized poly(arylene ether sulfone) copolymers with varying mole fractions of charge content and demonstrated their potential as sorbents for DAC. Molecular weight analysis determined high monomer conversion was achieved in <6 h and relatively high molecular weights for all copolymer compositions. Thermal analysis revealed all polymers had degradation temperatures >240 °C and a single glass transition temperature (T g ); the T g decreased with an increase in ion exchange capacity (IEC). Fractional free volume and water uptake percentage increased and water contact angle decreased with the number of QA sites when compared to a neutral, commercially available polysulfone (Udel® P-1700 PSU). Next, the novel series of ammonium-functionalized copolymers exhibited a moisture-mediated capture and release of atmospheric CO 2 . When exposed to air containing 30% relative humidity the polymers captured CO 2 and the capacity increased with the IEC. When the relative humidity was increased to 95% the samples released the CO 2 . This study demonstrates a promising CO 2 DAC sorbent and highlights the possibility for continuous DAC with purpose-built free-standing membranes.

42 ENGINEERING↗
DOE OSTI2023

One-Component, Vinyl-Functional Fluorosilicone Pastes for Direct Ink Write Additive Manufacturing

In this study, one-component (“all-in-one”) fluorosilicone pastes specifically designed for application in direct ink write (DIW) additive manufacturing (AM) have been developed. They consist of vinyl-functional, methyltrifluoropropyl-containing (MeTfpS) terpolysiloxane base polymer(s), hydrosilyl-functional cross-linker(s), UV-sensitive hydrosilylation catalyst, thixotropic additive, and trimethylsilylated fumed silica filler, with other additives that are optional. Their base polymers were completely amorphous and linear, with molecular weights (M n ) ranging from approximately 7000 to 50,000 and specifically targeted for the viscosity range ideal for DIW. These polymers were prepared by anionic ring-opening polymerizations (A-ROP) of appropriate mixtures of cyclic siloxanes initiated by oligomeric, difunctional tetramethylammonium silanolate in the presence of a difunctional tetramethyldivinyldisiloxane end-blocker and molecular weight regulator. Two series of these terpolymers were prepared: one containing 5 mol % MeTfpS repeat units but varying degrees of polymerization (DP) from 80 to 600 and the other containing 5, 10, and 15 mol % MeTfpS at a constant DP of 600. All polymers contained mostly random distributions of MeTfpS repeat units. The pastes were prepared by speed-mixing, ready for use in DIW, they exhibited ideal thixotropy, long-term (over a year) rheological stability, and can be quickly (within seconds) and permanently cured by room-temperature, UV-activated hydrosilylation in air. The resulting elastomers showed base polymer molecular weight- and composition-dependent stress-induced crystallization (SIC) at higher molecular weights and lower trifluoropropyl contents and tunable Shore A hardness (30A–40A) typical for soft polysiloxane rubbers. Preliminary DIW tests indicated excellent printability with high precision of printed shapes and clearly present these one-component pastes as prime candidates for simple and practical printing of silicone elastomer objects.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Direct Optical Lithography of CsPbX 3 Nanocrystals via Photoinduced Ligand Cleavage with Postpatterning Chemical Modification and Electronic Coupling

Microscale patterning of solution-processed nanomaterials is important for integration in functional devices. Colloidal lead halide perovskite (LHP) nanocrystals (NCs) can be particularly challenging to pattern due to their incompatibility with polar solvents and lability of surface ligands. Here, we introduce a direct photopatterning approach for LHP NCs through the binding and subsequent cleavage of a photosensitive oxime sulfonate ester (-C=N-OSOO-). The photosensitizer binds to the NCs through its sulfonate group and is cleaved at the N-O bond during photoirradiation with 405 nm light. This bond cleavage decreases the solubility of the NCs, which allows patterns to emerge upon development with toluene. Postpatterning ligand exchange results in photoluminescence quantum yields of up to 79%, while anion exchange provides tunability in the emission wavelength. Finally, the patterned NC films show photoconductive behavior, demonstrating that good electrical contact between the NCs can be established.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

Influence of Water Transport Across Microscale Bipolar Interfaces on the Performance of Direct Borohydride Fuel Cells

Direct borohydride fuel cells (DBFCs) can operate at double the voltage of proton exchange membrane fuel cells (PEMFCs) by employing an alkaline NaBH 4 fuel feed and an acidic H 2 O 2 oxidant feed. The pH-gradient-enabled microscale bipolar interface (PMBI) facilitates the creation and maintenance of an alkaline environment at the anode and an acidic environment at the cathode for the borohydride oxidation and peroxide reduction reactions. However, given the need to dissociate water at the interface to ensure ionic conduction, PMBI can be efficient only when anion exchange ionomer (AEI) moieties enable fast water transport for autoprotolysis. Herein, a series of polynorbornene-based AEIs with a range of water uptake values are examined to unravel the optimum water uptake required to enable high performance DBFCs. The DBFC with PMBI configuration containing the optimal AEI composition delivers a current density of 302 mA cm –2 at 1.5 V and a peak power density of 580 mW cm –2 at 1 V. This AEI composition exhibits high hydroxide ionic conductivity of 90.7 mS cm –1 at 80 °C with an IEC of 2.01 mequiv g –1 and demonstrates impressive chemical stability by retaining 98.75% of its initial ionic conductivity after immersion into anolyte (3 M KOH and 1.5 M NaBH 4 ) at 70 °C for 536 h.

25 ENERGY STORAGE↗