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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Gas Separation through Bilayer Silica, the Thinnest Possible Silica Membrane

Membrane-based gas separation processes can address concerns in energy and environment, but for many applications the permeance and selectivity of bulk membranes is insufficient for economical use. Theory and experiment suggest that permeance and selectivity can be increased by using two-dimensional materials with subnanometer pores as membranes. Motivated by experiments showing selective permeation of H 2 /CO mixtures through amorphous silica bilayers, here we perform a theoretical study of gas separation through silica bilayers. Using density functional theory calculations, we obtain geometries of crystalline free-standing silica bilayers (comprised of six-membered rings), as well as the seven-, eight-, and nine-membered rings that are observed in glassy silica bilayers, which arise due to Stone–Wales defects and vacancies. We then compute the potential energy barriers for gas passage through these various pore types for He, Ne, Ar, Kr, H 2 , N 2 , CO, and CO 2 gases, and use the data to assess their capability for selective gas separation. Our calculations indicate that crystalline bilayer silica, which is less than a nanometer thick, can be a high-selectivity and high-permeance membrane material for 3 He/ 4 He, He/natural gas, and H 2 /CO separations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Prediction of a measurable sign change in the Casimir force using a magnetic fluid

Here, we demonstrate quantum levitation controlled by Casimir forces acting between a polystyrene surface and a Teflon-coated metallic substrate immersed in a mixture of toluene and magnetite particles. This system experiences repulsion-attraction transitions in the Casimir interaction for distances where the effect is measurable. This Casimir trapping can be controlled by clever choices of metallic and ferrofluid materials, which are directly linked to the emergence of the trapping effect. Thermal and quantum contributions are investigated in detail, showing how the optical and magnetic properties of the ferrofluid and other materials affect the magnitude of the trapping and its distance range of observability.

Ma, Long [University of South Florida, Tampa, FL (↗
DOE OSTI2025

Compaction and Morphology of Lost Circulation Materials

Lost circulation material (LCM) selection is critical to effectively and efficiently treating wellbore fluid losses in geothermal drilling where costs of treatment can be as much as 30% of the total drilling cost. We conducted several uniaxial compaction experiments on 10 different materials and several material mixtures to identify critical mechanical parameters of each. Materials degraded at 200°C were also investigated to understand how elevated temperatures in geothermal wells would degrade their compaction behavior. Granular materials tended to have lower compressibility and higher compression resistance, while more elongated and softer materials had less mechanical stiffness. Mixing materials tended to moderate the mechanical behaviors while heating universally increased the compaction of materials. Microscopy showed that particle strength tended to correlate positively with roundness and circularity and negatively with elongation of a material. Convexity of the degraded and undegraded materials showed heating may have increased the convexity or roughness of the individual particles. In conclusion, we concluded that granular materials are likely to provide the best seals in wells but that a mixture of size distribution, mechanical rigidity, and elongation is more likely to form a better seal for geothermal wells.

annular pressure drilling↗
DOE OSTI2023

β- and γ-Counting for Pre-detonation Nuclear Forensics on Eu-155

Post-detonation nuclear forensics was performed at Los Alamos National Laboratory (LANL) on 155Eu, a fission product on the wing of the fission product production curve whose yield is sensitive to fission fuel and neutron energy. With a half-life of 4.753 years, 155Eu provides a longer-lived option for these measurements than other fission products with similar mass numbers. The Chemistry Division Group - Nuclear and Radiochemistry, at LANL routinely measures a suite of fission products from 235U fissions in thermal neutron flux experiments known as thermal calibration exercises, using a mixture of gas proportional β-decay counting and γ-spectrometry on HPGe detectors. The fission products of interest are reported relative to a high-yield reference fission product from the same sample to create a running average ratio specific to neutron energy and fuel type; Equation 1 below shows the ratio-of-ratios R-value measured fission products are reported in: R i x = [A( i X)/A( 99 Mo)] unknown [A( i X)/A( 99 Mo)] 235 U n,th where A denotes activity, i X is the nuclide of interest, and 235 U n,th denotes irradiations of 235 U with thermal neutrons. Measurements of unknown fission spectra are ratioed to a running-average of thermal calibration results, and the resulting R-value can be referred to as against a library of irradiation conditions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1974

Temperature dependence of the reactions of OH and HO2 with O3

Recent steady-state experiments involving the photolysis of O2-H2O mixtures at 1849 A conducted by DeMore (1973) have provided direct evidence for the catalytic cycle involving a reaction of ozone with OH in the first step and a reaction of ozone with HO2, which is produced in the first reaction, in the second step. The measurements of the rate constants for these reactions which had first been conducted at room temperature are now extended to the temperature range from 0 to 69 C.

Demore, W. B.↗
NASA NTRS1978

Gas Control System for HEAO-B

The HEAO-B Gas Control System consists of a high pressure gas storage supply together with distribution and regulation assemblies and their associated electronics for management of gas required for HEAO-B X-ray counter experiments. The Gas Control System replenishes a gas mixture (82 percent argon, 12.3 percent carbon dioxide, 5.7 percent xenon) in the counter volumes which is lost by: diffusion through controlled leakage plugs, diffusion through counter windows, and consumption resulting from periodic purges. The gas density in each counter volume is maintained constant to within 0.25 percent by comparison with a sealed reference volume. The system is fully redundant, capable of operating at atmospheric pressure as well as in a vacuum, contains interlocks which shut down gas flow in the event of either leakage or excessive pressure, and is able to shut down counter high voltage if counter pressure is abnormally low. The system is electronically controlled by ground command and self-sustaining in orbit for a period of at least one year.

Taylor, B.↗
NASA NTRS1982

Dynamic effects of combustion

The dynamic effects of combustion are due to the evolution of exothermic energy and its deposition in the compressible medium where the process takes place. The paper examines the dynamics of combustion phenomena, including ignition, turbulent flame propagation (inflammation), explosion, and detonation, with emphasis on their exothermic characteristics. Ignition and explosion are treated as problems of nonlinear mechanics, and their dynamic behavior is described in terms of phase space models and cinematographic laser shear interferograms. The results of a numerical random vortex model of turbulent flame propagation are confirmed in a combustion tunnel experiment, where it was observed that a fresh mixture of burnt and unburnt gases can sustain combustion with a relatively small expenditure of overall mass flow, due to the increasing specific volume of burnt gases inside the flame front. An isentropic pressure wave is found to precede the accelerating flame in the process of detonation, and components of this presssure wave are shown to propagate at local sonic velocities.

Oppenheim, A. K.↗
NASA NTRS1985

Purification and Cultivation of Human Pituitary Growth Hormones Secreting Cells

The rat and human pituitary gland contains a mixture of hormone producing cell types. The separation of cells which make growth hormone (GH) is attempted for the purpose of understanding how the hormone molecule is made within the pituitary cell; what form(s) it takes within the cell; and what form(s) GH assumes as it leaves the cell. Since GH has a number of biological targets (e.g., muscle, liver, bone), the assessment of the activities of the intracellular/extracellular GH by new and sensitive bioassays. GH cells contained in the mixture was separated by free flow electrophoresis. These experiments show that GH cells have different electrophoretic mobilities. This is relevant to NASA since a lack of GH could be a prime causative factor in muscle atrophy. Further, GH has recently been implicated in the etiology of motion sickness in space. Continous flow electrophoresis experiment on STS-8 showed that GH cells could be partially separated in microgravity. However, definitive cell culture studies could not be done due to insufficient cell recoveries.

Hymer, W. C.↗
NASA NTRS1987

Precision ozone calibration system based on vapor pressures of ozone

A precision ozone calibration system for stratospheric research has been developed and evaluated. Vapor pressures above solid ozone are mixed with a carrier gas (N2) to produce stratospheric ozone mixing ratios at total pressures of 1 to cover 20 torr. The uncertainty in the ozone mixing ratios is approximately + or - 1.5 percent, the stability of ozone is + or - 0.3 percent. Experiments to be calibrated may sample the gas mixture over a wide range of flow rates; the maximum throughput of gas with corrections of less than 1 percent to ozone is about 200 torr 1/min. A mass spectrometer system continuously monitors the purity and stability of the N2-O3 gas mixture.

Mauersberger, K.↗
NASA NTRS2000

The Effects of pH on the Growth and Aspect Ratio of Chicken Egg White Lysozyme Crystals Prepared in Different Buffers

We have measured the nucleation and aspect ratio of CEWL crystals grown by vapor diffusion in acetate, butyrate, carbonate, succinate, and phosphate buffers in a range of pH spanning the pK(sub a) of these buffers. The nucleation numbers drop off significantly in the vicinity of pK(sub a) for each of the buffers except the phosphate system, in which we used only the pH range around the second titration point(pK2). There is a concomitant increase in the sizes of the crystals. Some typical nucleation number results are shown. These data support and extend other observations. In addition, we have examined changes in aspect ratio which accompany the suppression of nucleation within each buffer system. The length of the face in the [001] direction was measured, and compared to the width of the (110) face in the [110] type directions. We find that while the aspect ratio of the crystals is affected by pH, it is dominated by a correlation with the size of the crystals. Small crystals are longer in the [0011 direction than crystals that are larger (higher pH within a buffer system). This relationship is found to hold independent of the choice of buffer. These results are consistent with those of Judge et al, who used a batch process which resulted in uniform sizing of crystals at each pH. In these experiments, we specifically avoid agitating the protein/salt buffer mixture when combining the two. This permits the formation of a range of sizes at a given pH. The results for a .05 M acetate 5% NaCl buffer are also shown. We will discuss these results in light of a growth model.

Gibson, U. J.↗
DOE OSTI2016

HDTHe calorimetry v.1.0

The software generates predicted results of differential scanning calorimetry experiments for samples of palladium in a perforated capsule in an atmosphere containing a mixture of hydrogen isotopologues and helium. It can also be used to predict the results of absorption-desorption experiments at constant temperature and solid-phase isotopic ratio.

Robinson, DavidB.↗
DOE OSTI2016

Quantum state-resolved, bulk gas energetics: Comparison of theory and experiment

Until very recently, the computational model of state-to-state energy transfer in large gas mixtures, introduced by the author and co-workers, has had little experimental data with which to assess the accuracy of its predictions. In a novel experiment, Alghazi et al. [Chem. Phys. 448, 76 (2015)] followed the equilibration of highly vibrationally excited CsH(D) in baths of H{sub 2}(D{sub 2}) with simultaneous time- and quantum state-resolution. Modal temperatures of vibration, rotation, and translation for CsH(D) were obtained and presented as a function of pump-probe delay time. Here the data from this study are used as a test of the accuracy of the computational method, and in addition, the consequent changes in bath gas modal temperatures, not obtainable in the experiment, are predicted. Despite large discrepancies between initial CsH(D) vibrational states in the experiment and those available using the computational model, the quality of agreement is sufficient to conclude that the model’s predictions constitute at least a very good representation of the overall equilibration that, for some measurements, is very accurate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Antiwear Properties of Binary Ashless Blend of Phosphonium Ionic Liquids and Borate Esters in Partially Formulated Oil (No Zn)

Here, interaction of ionic liquid (IL) and borate esters (SBs) as antiwear (AW) additives with steel surfaces in tribological contacts was examined using blends which contained no prior AW additives but all the other ingredients present in a fully formulated engine oil. In detail, low phosphorus oil blends were prepared by adding trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate (P_DEHP) at 700ppm phosphorus and 2-methoxy-4,4,6-trimethyl-1,3,2-dioxaborinane or trimethoxyboroxine at 200ppm boron treat rate to a partially formulated oil. The tribological properties of these novel ionic liquid (IL) additive and IL+SB additive mixtures were compared with those of zinc dialkyldithiophosphate (ZDDP) at equal phosphorus levels in the oil blends. Tribological experiments with a reciprocating cylinder on flat contact revealed that both P_DEHP and binary mixtures of P_DEHP+SB offer superior wear protection than ZDDP and the partially formulated oil without AW additives, expressed by a wear reduction of minimum 50%. X-ray absorption near edge structure spectroscopy (XANES) analysis revealed that tribologically formed films are primarily composed of calcium phosphate for oils with AW additives. The interaction of P_DEHP with SB results in additional boron oxide/boric acid and to some extent boron phosphate domains incorporated into the tribofilms.

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

DME-Propane Ignition Delay Time Measurements at Mixing Controlled Compression Ignition Engine-Relevant Conditions

The blend of dimethyl ether (DME, CH 3 OCH 3 ) and propane (C 3 H 8 ) is a potentially renewable fuel mixture that has the potential to replace diesel in compression ignition engines. The combination can potentially reduce particulate and greenhouse gas emissions compared to a conventional diesel engine operating under similar conditions. However, detailed conceptual and simulation studies must be conducted before adopting a new fuel on a compression ignition engine. For these simulations, accurate chemical kinetic models are necessary. However, the validity of chemical kinetic mechanisms in the literature is unknown for mixing controlled compression ignition (MCCI) engine operating conditions. Hence, in this work, we studied the ignition of dimethyl ether (DME) and propane blends in a shock tube at MCCI engine conditions. Ignition delay time (IDT) data was collected behind the reflected shock for DME-propane mixtures for heavy-duty compression ignition (CI) engine parameters. Undiluted experiments spanning temperatures of 700 to 1100 K and pressures of 55 to 84 bar for various blends (100% CH 3 OCH 3 / 0% C 3 H 8, 100% C 3 H 8 / 0% CH 3 OCH 3 , 60% CH 3 OCH 3 / 40% C 3 H 8 ) of DME and propane were combusted in synthetic air (21% O 2 / 79% N 2 ). Some experiments were conducted at higher pressures (90-120 bar) to understand model performance at these conditions. Comparisons of IDT were made with the predictions of recent chemical kinetic mechanisms for DME-propane mixture, including the Aramco3.0, NUIG, and Dames et al. mechanisms. All mechanisms overpredicted IDT compared to experimental values. Sensitivity analysis was conducted with Dames et al. model, and critical reactions sensitive to IDT of DME-propane mixture near 100 bar are outlined.

Mohammed, Zuhayr Pasha↗
DOE OSTI2014

Guest Molecule Exchange Kinetics for the 2012 Ignik Sikumi Gas Hydrate Field Trial

A commercially viable technology for producing methane from natural gas hydrate reservoirs remains elusive. Short-term depressurization field tests have demonstrated the potential for producing natural gas via dissociation of the clathrate structure, but the long-term performance of the depressurization technology ultimately requires a heat source to sustain the dissociation. A decade of laboratory experiments and theoretical studies have demonstrated the exchange of pure CO2 and N2-CO2 mixtures with CH4 in sI gas hydrates, yielding critical information about molecular mechanisms, recoveries, and exchange kinetics. Findings indicated the potential for producing natural gas with little to no production of water and rapid exchange kinetics, generating sufficient interest in the guest-molecule exchange technology for a field test. In 2012 the U.S. DOE/NETL, ConocoPhillips Company, and Japan Oil, Gas and Metals National Corporation jointly sponsored the first field trial of injecting a mixture of N2-CO2 into a CH4-hydrate bearing formation beneath the permafrost on the Alaska North Slope. Known as the Ignik Sikumi #1 Gas Hydrate Field Trial, this experiment involved three stages: 1) the injection of a N2-CO2 mixture into a targeted hydrate-bearing layer, 2) a 4-day pressurized soaking period, and 3) a sustained depressurization and fluid production period. Data collected during the three stages of the field trial were made available after an extensive quality check. These data included continuous temperature and pressure logs, injected and recovered fluid compositions and volumes. The Ignik Sikumi #1 data set is extensive, but contains no direct evidence of the guest-molecule exchange process. This investigation is directed at using numerical simulation to provide an interpretation of the collected data. A numerical simulator, STOMP-HYDT-KE, was recently completed that solves conservation equations for energy, water, mobile fluid guest molecules, and hydrate guest molecules, for up to three gas hydrate guest molecules: CH4, CO2, and N2. The independent tracking of mobile fluid and hydrate guest molecules allows for the kinetic exchange of guest molecules between the mobile fluids and hydrate. The particular interest of this numerical investigation is to determine whether kinetic exchange parameters, determined from laboratory-scale experiments, are directly applicable to interpreting the Ignik Sikumi #1 data.

Alaska North Slope↗
DOE OSTI2015

Experimental and Kinetic Modeling Study of 2-Methyl-2-Butene: Allylic Hydrocarbon Kinetics

Two experimental studies have been carried out on the oxidation of 2-methyl-2-butene, one measuring ignition delay times behind reflected shock waves in a stainless steel shock tube, and the other measuring fuel, intermediate, and product species mole fractions in a jet-stirred reactor (JSR). The shock tube ignition experiments were carried out at three different pressures, approximately 1.7, 11.2, and 31 atm, and at each pressure, fuel-lean (Φ = 0.5), stoichiometric (Φ = 1.0), and fuel-rich (Φ = 2.0) mixtures were examined, with each fuel/oxygen mixture diluted in 99% Ar, for initial postshock temperatures between 1330 and 1730 K. The JSR experiments were performed at nearly atmospheric pressure (800 Torr), with stoichiometric fuel/oxygen mixtures with 0.01 mole fraction of 2M2B fuel, a residence time in the reactor of 1.5 s, and mole fractions of 36 different chemical species were measured over a temperature range from 600 to 1150 K. These JSR experiments represent the first such study reporting detailed species measurements for an unsaturated, branched hydrocarbon fuel larger than iso-butene. A detailed chemical kinetic reaction mechanism was developed to study the important reaction pathways in these experiments, with particular attention on the role played by allylic C–H bonds and allylic pentenyl radicals. The results show that, at high temperatures, this olefinic fuel reacts rapidly, similar to related alkane fuels, but the pronounced thermal stability of the allylic pentenyl species inhibits low temperature reactivity, so 2M2B does not produce “cool flames” or negative temperature coefficient behavior. Furthermore, the connections between olefin hydrocarbon fuels, resulting allylic fuel radicals, the resulting lack of low-temperature reactivity, and the gasoline engine concept of octane sensitivity are discussed.

2-methyl-2-butane↗
DOE OSTI2018

Thermal Model of the AGR-5/6/7 Experiment

Several fuel and material irradiation experiments have been planned for the U.S. Department of Energy Advanced Gas Reactor Fuel Development and Qualification Program, which supports the development and qualification of tristructural isotropic (TRISO) coated particle fuel for use in high-temperature gas-cooled reactors. The goals of these experiments are to provide irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, support development of fuel performance models and codes, and provide irradiated fuel and materials for post-irradiation examination and safety testing. Originally planned and named as separate fuel experiments, but subsequently combined into a single test train, AGR-5/6/7 will test low-enriched uranium oxycarbide (UCO – a heterogeneous mixture of uranium oxide and uranium carbide) TRISO fuel. The AGR-5/6 portion of the experiment will provide data to support qualification of the selected reference fuel design, while the AGR-7 portion will serve as a margin test, irradiating the fuel beyond normal operating conditions. A thermal finite element model has been created for the five capsules comprising the AGR-5/6/7 experiment. Heat rates from a physics analysis are imported into the model along with fast neutron fluence. Graphite shrinkage due to the fast neutron fluence is incorporated into the model. Gas gaps change as a function of fast neutron fluence. Radiation heat transfer is a major contributor in this model. This is a large model with more than 1 million finite element brick elements. More than 150 different parts are modeled in the finite element model and communicate with each other from a heat transfer sense. More than 50 thermocouples are used in the experiment and are compared to actual measurements. The experiment is composed of five separate stainless steel capsules all welded together. Each capsule has its own Helium/.Neon gas mixture to help control the temperature of the capsule.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗