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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

HERO WEC V1: Design and Experimental Data Collection Efforts

The Hydraulic and Electric Reverse Osmosis Wave Energy Converter (HERO WEC) is a research platform aimed at developing a modular, small-scale wave-powered desalination system for remote and disaster-response applications. Funded by the Department of Energy (DOE)'s Water Power Technologies Office (WPTO), the project aims to advance wave-powered desalination by developing and testing a small-scale, modular wave energy converter (WEC). The insights gained from this project will help guide the design and development of larger-scale wave energy devices as well as the integration of marine energy and reverse osmosis (RO) desalination. The HERO WEC was initially developed to derisk the Waves to Water prize, enabling the staff to practice WEC deployment and recovery, while optimizing installation protocols ologies, aiming to advance the broader fields of marine energy and water treatment.

13 HYDRO ENERGY↗
DOE OSTI2010

Passive Measurement of Hydrogen Ground State Rotational and Vibrational Temperatures in Kinetic Plasmas

A dipole-quadrupole electron-impact excitation model, consistent with molecular symmetry rules, is presented to fit ro-vibronic spectra of the hydrogen Fulcher-α Q-branch line emissions for passively measuring the rotational temperature of hydrogen neutral molecules in kinetic plasmas with the coronal equilibrium approximation. A quasi-rotational temperature and quadrupole contribution factor are adjustable parameters in the model. Quadrupole excitation is possible due to a violation of the 1st Born approximation for low to medium energy electrons (up to several hundred eV). The Born-Oppenheimer and Franck-Condon approximations are implicitly shown to hold. A quadrupole contribution of 10% is shown to fit experimental data at several temperatures from different experiments with electron energies from several to 100 eV. A convenient chart is produced to graphically determine the vibrational temperature of the hydrogen molecules from diagonal band intensities, if the ground state distribution is Boltzmann. Hydrogen vibrational modes are long-lived, surviving up to thousands of wall collisions, consistent with multiple other molecular dynamics computational results. The importance of inter-molecular collisions during a plasma pulse are also discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

SERDP PFAS 2.0 - An infrared spectral database for gas-phase quantitation of volatile per- and polyfluoroalkyl substances (PFAS)

We report the construction of a database of vetted infrared spectra specifically targeting volatile fluorocarbon gases that may be emitted during thermal treatment of per- and polyfluoroalkyl substances (PFAS) to assist understanding of treatment processes and improve quantification. To populate this database, protocols derived from the Pacific Northwest National Laboratory (PNNL) infrared spectral database are used, curtailing the species selection for this data set. Each spectrum in the database is a weighted average derived from 10 or more individual measurements at different partial pressures (static method) or flow rates (dissemination method) to yield good fidelity of both strong and weak infrared signatures, with each composite spectrum ranging from = 6500 cm-1 to = 600 cm-1 with an apodized resolution of 0.112 cm-1. This resolution was chosen to fully resolve all spectral features, recognizing that atmospheric pressure broadening results in nearly all ro-vibrational lines having linewidths = 0.1 cm-1. As an example case, application of the database is demonstrated via identification and quantification of dominant 1H-perfluoroheptane and perfluorohept-1-ene fluorocarbon products resulting from thermal decomposition of perfluorooctanoate (PFOA) below 450 °C.

Infrared, Gas-phase spectra, FTIR, Spectral databa↗
DOE OSTI2021

Pressure Exchanger for Energy Recovery in a Trans-Critical CO2 Refrigeration System

Trans-critical CO2 vapor compression (VC) refrigeration cycles require a high compression ratio, which is associated with high expansion losses. To recover these expansion losses, a pressure exchange process between the low- and high-pressure sides of the VC cycle is proposed and examined in this study. The proposed pressure exchange system is an open type constant volume process where the high- and low-pressure flows mix inside the system. This prototype is inspired by the pressure exchangers used in reverse-osmosis (RO) desalination systems. In this system, a 2D model was generated and modeled using the computational fluid dynamics (CFD) technique. The numerical model ignored any losses due to leakage or hydraulic friction and the process is considered adiabatic. For the modeling, it was assumed that the inlet conditions for the two pressure exchanger flows are similar to the flow conditions at the evaporator and gas cooler outlets in a VC cycle. Two parameters are examined to test the validity of the system and understand their effect on the performance, including the inlet flow rate represented by the inlet velocity and the process time represented by the speed of rotation. A total of nine cases were simulated and analyzed in this study.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

State-of-the-Art Organic- and Inorganic-Based Hollow Fiber Membranes in Liquid and Gas Applications: Looking Back and Beyond

The aggravation of environmental problems such as water scarcity and air pollution has called upon the need for a sustainable solution globally. Membrane technology, owing to its simplicity, sustainability, and cost-effectiveness, has emerged as one of the favorable technologies for water and air purification. Among all of the membrane configurations, hollow fiber membranes hold promise due to their outstanding packing density and ease of module assembly. Herein, this review systematically outlines the fundamentals of hollow fiber membranes, which comprise the structural analyses and phase inversion mechanism. Furthermore, illustrations of the latest advances in the fabrication of organic, inorganic, and composite hollow fiber membranes are presented. Key findings on the utilization of hollow fiber membranes in microfiltration (MF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO), pervaporation, gas and vapor separation, membrane distillation, and membrane contactor are also reported. Moreover, the applications in nuclear waste treatment and biomedical fields such as hemodialysis and drug delivery are emphasized. Subsequently, the emerging R&D areas, precisely on green fabrication and modification techniques as well as sustainable materials for hollow fiber membranes, are highlighted. Last but not least, this review offers invigorating perspectives on the future directions for the design of next-generation hollow fiber membranes for various applications. As such, the comprehensive and critical insights gained in this review are anticipated to provide a new research doorway to stimulate the future development and optimization of hollow fiber membranes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

EFFECTIVE HYPERFINE-STRUCTURE FUNCTIONS OF AMMONIA

The hyperfine structure of the rotation-inversion ( v {sub 2} = 0{sup +}, 0{sup −}, 1{sup +}, 1{sup −}) states of the {sup 14}NH{sub 3} and {sup 15}NH{sub 3} ammonia isotopomers is rationalized in terms of effective (ro-inversional) hyperfine-structure (hfs) functions. These are determined by fitting to available experimental data using the Hougen’s effective hyperfine-structure Hamiltonian within the framework of the non-rigid inverter theory. Involving only a moderate number of mass independent fitting parameters, the fitted hfs functions provide a fairly close reproduction of a large majority of available experimental data, thus evidencing adequacy of these functions for reliable prediction. In future experiments, this may help us derive spectroscopic constants of observed inversion and rotation-inversion transitions deperturbed from hyperfine effects. The deperturbed band centers of ammonia come to the forefront of fundamental physics especially as the probes of a variable proton-to-electron mass ratio.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2016

CONSTRAINTS ON THE PRESENCE OF SiO GAS IN THE DEBRIS DISK OF HD 172555

We have carried out two sets of observations to quantify the properties of SiO gas in the unusual HD 172555 debris disk: (1) a search for the J = 8–7 rotational transition from the vibrational ground state, carried out with the Atacama Pathfinder EXperiment (APEX) submillimeter telescope and heterodyne receiver at 863 μ m and (2) a search at 8.3 μ m for the P(17) ro-vibrational transition of gas phase SiO, carried out with the Very Large Telescope (VLT)/VISIR with a resolution, λ /Δ λ , of 30,000. The APEX measurement resulted in a 3.3 σ detection of an interstellar feature, but only an upper limit to emission at the radial velocity and line width expected from HD 172555. The VLT/VISIR result was also an upper limit. These were used to provide limits for the abundance of gas phase SiO for a range of temperatures. The upper limit from our APEX detection, assuming an 8000 K primary star photospheric excitation, falls more than an order of magnitude below the self-shielding stability threshold derived by Johnson et al. (2012). Our results thus favor a solid-state origin for the 8.3 μ m feature seen in the Spitzer IRS spectrum of the circumstellar excess emission and the production of circumstellar O i and Si i by SiO UV photolysis. The implications of these estimates are explored in the framework of models of the HD 172555 circumstellar disk.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

DETAILED ANALYSIS OF NEAR-IR WATER (H{sub 2}O) EMISSION IN COMET C/2014 Q2 (LOVEJOY) WITH THE GIANO/TNG SPECTROGRAPH

We observed the Oort cloud comet C/2014 Q2 (Lovejoy) on 2015 January 31 and February 1 and 2 at a heliocentric distance of 1.3 au and geocentric distance of 0.8 au during its approach to the Sun. Comet Lovejoy was observed with GIANO, the near-infrared high-resolution spectrograph mounted at the Nasmyth-A focus of the TNG (Telescopio Nazionale Galileo) telescope in La Palma, Canary Islands, Spain. We detected strong emissions of radical CN and water, along with many emission features of unidentified origin, across the 1–2.5 μ m region. Spectral lines from eight ro-vibrational bands of H{sub 2}O were detected, six of them for the first time. We quantified the water production rate [ Q (H{sub 2}O), (3.11 ± 0.14) × 10{sup 29} s{sup −1}] by comparing the calibrated line fluxes with the Goddard full non-resonance cascade fluorescence model for H{sub 2}O. The production rates of ortho-water [ Q (H{sub 2}O){sup ORTHO}, (2.33 ± 0.11) × 10{sup 29} s{sup −1}] and para-water [ Q (H{sub 2}O){sup PARA}, (0.87 ± 0.21) × 1029 s{sup −1}] provide a measure of the ortho-to-para ratio (2.70 ± 0.76)). The confidence limits are not small enough to provide a critical test of the nuclear spin temperature.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

The abundance of C{sub 2}H{sub 4} in the circumstellar envelope of IRC+10216

High spectral resolution mid-IR observations of ethylene (C{sub 2}H{sub 4}) toward the AGB star IRC+10216 were obtained using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF). 80 ro-vibrational lines from the 10.5 μm vibrational mode ν{sub 7} with J ≲ 30 were detected in absorption. The observed lines are divided into two groups with rotational temperatures of 105 and 400 K (warm and hot lines). The warm lines peak at ≃ −14 km s{sup −1} with respect to the systemic velocity, suggesting that they are mostly formed outwards from ≃20R{sub ⋆}. The hot lines are centered at −10 km s{sup −1} indicating that they come from a shell between 10 and 20R{sub ⋆}. 35% of the observed lines are unblended and can be fitted with a code developed to model the emission of a spherically symmetric circumstellar envelope. The analysis of several scenarios reveals that the C{sub 2}H{sub 4} abundance relative to H{sub 2} in the range 5−20R{sub ⋆} is 6.9×10{sup −8} on average and it could be as high as 1.1 × 10{sup −7}. Beyond 20R{sub ⋆}, it is 8.2 × 10{sup −8}. The total column density is (6.5 ± 3.0) × 10{sup 15} cm{sup −2}. C{sub 2}H{sub 4} is found to be rotationally under local thermodynamical equilibrium (LTE) and vibrationally out of LTE. One of the scenarios that best reproduce the observations suggests that up to 25% of the C{sub 2}H{sub 4} molecules at 20R{sub ⋆} could condense onto dust grains. This possible depletion would not significantly influence the gas acceleration although it could play a role in the surface chemistry on the dust grains.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

STELLAR EVIDENCE THAT THE SOLAR DYNAMO MAY BE IN TRANSITION

Precise photometry from the Kepler space telescope allows not only the measurement of rotation in solar-type field stars, but also the determination of reliable masses and ages from asteroseismology. These critical data have recently provided the first opportunity to calibrate rotation–age relations for stars older than the Sun. The evolutionary picture that emerges is surprising: beyond middle-age the efficiency of magnetic braking is dramatically reduced, implying a fundamental change in angular momentum loss beyond a critical Rossby number (Ro ∼ 2). We compile published chromospheric activity measurements for the sample of Kepler asteroseismic targets that were used to establish the new rotation–age relations. We use these data along with a sample of well-characterized solar analogs from the Mount Wilson HK survey to develop a qualitative scenario connecting the evolution of chromospheric activity to a fundamental shift in the character of differential rotation. We conclude that the Sun may be in a transitional evolutionary phase, and that its magnetic cycle might represent a special case of stellar dynamo theory.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Seawater pH reconstruction using boron isotopes in multiple planktonic foraminifera species with different depth habitats and their potential to constrain pH and <i>p</i>CO<sub>2</sub> gradients

Boron isotope systematics of planktonic foraminifera from core-top sediments and culture experiments have been studied to investigate the sensitivity ofδ11B of calcite tests to seawater pH. However, our knowledge of the relationship between δ11B and pH remains incomplete for many taxa. Thus, to expand the potential scope of application of this proxy, we report δ11B data for seven different species of planktonic foraminifera from sediment core tops. We utilize a method for the measurement of small samples of foraminifera and calculate the δ11B-calcite sensitivity to pH for Globigerinoides ruber, Trilobus sacculifer (sacc or without sacc), Orbulina universa, Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, Globorotalia menardii, and Globorotalia tumida, including for unstudied core tops and species. These taxa have diverse ecological preferences and are from sites that span a range of oceanographic regimes, including some that are in regions of air–sea equilibrium and others that are out of equilibrium with the atmosphere. The sensitivity of δ11Bcarbonate to δ11Bborate (e.g., Δδ11Bcarbonate/Δδ11Bborate) in core tops is consistent with previous studies for T. sacculifer and G. ruber and close to unity for N. dutertrei, O. universa, and combined deep-dwelling species. Deep-dwelling species closely follow the core-top calibration fo rO. universa, which is attributed to respiration-driven microenvironments likely caused by light limitation and/or symbiont–host interactions. Our data support the premise that utilizing boron isotope measurements of multiple species within a sediment core can be utilized to constrain vertical profiles of pH andpCO2 at sites spanning different oceanic regimes, thereby constraining changes in vertical pH gradients and yielding insights into the past behavior of the oceanic carbon pumps.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Thermochemical Data for Furan-based Monomer Candidates for Frontal Ring-Opening Metathesis Polymerization (FROMP)

This dataset includes 471 furan-based monomer candidates for frontal ring-opening metathesis polymerization (FROMP) and relevant thermochemistry as calculated with density functional theory (DFT). The monomer candidates were combinatorically enumerated using Diels-Alder reactions of furan derivatives as dienes and four types of dienophiles (alkenes, alkynes, allenes, and benzynes). Common substituents were enumerated for the dienophile classes, and methyl substitution on the diene was explored. We used the SMILES arbitrary target specification (SMARTS) language to produce monomers and ring-opened structures from diene and dienophile precursor SMILES, and we studied the ring-opening reaction using a homodesmotic equation with ethene. RDKit conformers were initially generated from SMILES, then optimized with GFN2-xTB. The two conformers lowest in energy were then optimized with DFT using the wb97x-D3 functional, def2-TZVP basis set, and def2/J auxiliary basis set. Gibbs free energy corrections were obtained through frequency calculations. Structures with imaginary frequencies below -50 cm^{-1} were excluded from this work, and smaller imaginary modes were flipped to be positive for free energy calculations. Modes below 50 cm^{-1} were treated with the modified rigid rotor approximation, and all thermochemical values were calculated at T=200C. The CSV file contains the monomer SMILES, the free energy of reaction for Diels-Alder addition (G_DA_200), and the enthalpy of the ring-opening reaction (H_RO_200). All energies are given in kcal/mol. An interactive HTML is also included to visualize the monomers in this dataset.

Chua, Lauren↗
NASA NTRS1973

Contact problem for an elastic reinforcement bonded to an elastic plate

The stiffening layer is treated as an elastic membrane and the base plate is assumed to be an elastic continuum. The bonding between the two materials is assumed to be either one of direct adhesion ro through a thin adhesive layer which is treated as a shear spring. The solution for the simple case in which both the stiffener and the base plate are treated as membranes is also given. The contact stress is obtained for a series of numerical examples. In the direct adhesion case the contact stress becomes infinite at the stiffener ends with a typical square root singularity for the continuum model, and behaving as a delta function for the membrane model. In the case of bonding through an adhesive layer the contact stress becomes finite and continuous along the entire contact area.

Erdogan, F.↗
NASA NTRS1974

Wash water solids removal system study

During wash water purification, surfactants tend to precipitate and foul the RO membranes, causing water flux decline and loss of salt rejection. The use of 165 to 190 ppm ferric chloride and optionally 0.25 to 1.0 ppm polymeric flocculate precipitates 92 to 96 percent of the surfactant from an Olive Leaf Soap based wash water. Crossflow filtration and pressure filtration yield good soap rejection at high water flux rates. Post-treatment of the chemically pretreated and filtered wash water with activated charcoal removes the residual soap down to an undetectable level.

Source record↗
NASA NTRS1974

Infrared pumping processes for SiO masers

The J = 2 to 1 transition of the first excited vibrational state (v = 1) Si(28)O(16) has recently been shown to produce maser amplification near 86,245 MHz in Orion A and in several stars. Two possible pumping mechanisms are proposed for such masers. One involves the near coincidence between the frequencies of the 1-0 (RO) and 3-2 (R18) transitions in Si(28)O(16). The other requires emission by SiO and reabsorption without the necessity for an accidental frequency coincidence. Each of these types of mechanisms may occur for other transitions of molecules in a medium illuminated by intense infrared radiation, or with strong temperature gradients.

Geballe, T. R.↗
NASA NTRS1980

Two-photon excitation of nitric oxide fluorescence as a temperature indicator in unsteady gas-dynamic processes

A laser induced fluorescence technique, suitable for measuring fluctuating temperatures in cold turbulent flows containing very low concentrations of nitric oxide is described. Temperatures below 300 K may be resolved with signal to noise ratios greater than 50 to 1 using high peak power, tunable dye lasers. The method relies on the two photon excitation of selected ro-vibronic transitions. The analysis includes the effects of fluorescence quenching and shows the technique to be effective at all densities below ambient. Signal to noise ratio estimates are based on a preliminary measurement of the two photon absorptivity for a selected rotational transition in the NO gamma (0,0) band.

Mckenzie, R. L.↗
NASA NTRS1981

Heterodyne frequency measurements of 13CO2 laser hot band transitions

Careful measurements by means of stabilized CO2 lasers are presented for the frequencies of 28 lines in the P-branch of the 01 0 0-(11 1 0, 03 1 0)I band of (C-13)(0-16)2, observed in laser emission, and three lines in the R-branch, observed in absorption with a diode laser. A significant improvement in the ro-vibrational constants has been obtained from a least squares fit to these data, demonstrating that the laser lines stabilized by natural absorption techniques provide convenient, accurate frequency references near 11.7 microns with an uncertainty of less than 0.1 MHz.

Petersen, F. R.↗