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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Nuclear Thermal Rocket/Vehicle Characteristics And Sensitivity Trades For NASA's Mars Design Reference Architecture (DRA) 5.0 Study

This paper summarizes Phase I and II analysis results from NASA's recent Mars DRA 5.0 study which re-examined mission, payload and transportation system requirements for a human Mars landing mission in the post-2030 timeframe. Nuclear thermal rocket (NTR) propulsion was again identified as the preferred in-space transportation system over chemical/aerobrake because of its higher specific impulse (I(sub sp)) capability, increased tolerance to payload mass growth and architecture changes, and lower total initial mass in low Earth orbit (IMLEO) which is important for reducing the number of Ares-V heavy lift launches and overall mission cost. DRA 5.0 features a long surface stay (approximately 500 days) split mission using separate cargo and crewed Mars transfer vehicles (MTVs). All vehicles utilize a common core propulsion stage with three 25 klbf composite fuel NERVA-derived NTR engines (T(sub ex) approximately 2650 - 2700 K, p(sub ch) approximately 1000 psia, epsilon approximately 300:1, I(sub sp) approximately 900 - 910 s, engine thrust-toweight ratio approximately 3.43) to perform all primary mission maneuvers. Two cargo flights, utilizing 1-way minimum energy trajectories, pre-deploy a cargo lander to the surface and a habitat lander into a 24-hour elliptical Mars parking orbit where it remains until the arrival of the crewed MTV during the next mission opportunity (approximately 26 months later). The cargo payload elements aerocapture (AC) into Mars orbit and are enclosed within a large triconicshaped aeroshell which functions as payload shroud during launch, then as an aerobrake and thermal protection system during Mars orbit capture and subsequent entry, descent and landing (EDL) on Mars. The all propulsive crewed MTV is a 0-gE vehicle design that utilizes a fast conjunction trajectory that allows approximately 6-7 month 1-way transit times to and from Mars. Four 12.5 kW(sub e) per 125 square meter rectangular photovoltaic arrays provide the crewed MTV with approximately 50 kW(sub e) of electrical power in Mars orbit for crew life support and spacecraft subsystem needs. Vehicle assembly involves autonomous Earth orbit rendezvous and docking between the propulsion stages, in-line propellant tanks and payload elements. Nine Ares-V launches -- five for the two cargo MTVs and four for the crewed MTV -- deliver the key components for the three MTVs. Details on mission, payload, engine and vehicle characteristics and requirements are presented and the results of key trade studies are discussed.

Borowski, Stanley K.↗
NASA NTRS2021

Assessment of VIIRS Day-Night Band High Gain Calibration Using Stars

The VIIRS has a unique spectral band that can sense reflected light from space during both day and nighttime, thus referred to as the day-night band (DNB). This band operates in three different gain stages: low, mid, and high gain (LG, MG, and HG) that cover a remarkable dynamic range with its HG stage being extremely sensitive to low-light scenes. Similar to its reflective solar bands, the VIIRS uses an on-board solar diffuser for its DNB LG stage calibration, whereas the DNB MG and HG calibrations are performed using relative or ratioing approaches. In this paper, we provide an assessment of VIIRS DNB HG calibrations using stars that appear in the field-of-view of its space view (SV), focusing on the computation of the gain trending and associated tool development. We also describe various strategies and procedures developed for DNB HG calibration stability monitoring and inter-comparisons among different VIIRS instruments and discuss some of the complications and limits to this approach, including under-sampling of the stellar image, saturation, and crowding. For S-NPP VIIRS, it includes the use of the modulated relative spectral response (RSR) resulting from wavelength-dependent degradation of the sensor optics. Results show that the star-based response trending for the DNB HG is consistent with that derived from on-board solar diffuser and that the calibration difference between S-NPP and N-20 VIIRS DNB requires additional effort to address, especially for research studies and applications using data from both sensors.

VIIRS↗
DOE OSTI2016

Uncertainty quantification of measured quantities for a HCCI engine: mass-average quantities and perofrmances

UQHCCI_2 propagates the uncertainties of mass-average quantities (temperature, heat capacity ratio) and the output performances (IMEP, heat release, CA50 and RI) of a HCCI engine test bench using the pressure trace, and intake and exhaust molar fraction and IVC temperature distributions, as inputs (those inputs may be computed using another code UQHCCI_2, or entered independently).

Petitpas, Guillaume↗
DOE OSTI2019

Optimization of Dual Axis Asymmetric Cavity for Energy Recovery Linac

Optimization of the dual axis asymmetric cavity was performed to minimize the ratio of the peak magnetic and electric fields values to the accelerating voltage, to increase the distance between operating and neighbouring modes as well as to reduce the manufacturing cost of the cavity. To reach the goals several solutions have been suggested bringing the ratios to the acceptable values and leading to simplification of the manufacturing of the structure.

Shashkov, Ya. V.↗
DOE OSTI2022

Thermal cross section measurements at the RPI LINAC [Abstract]

Recently, a cold moderator was designed and developed for use at the RPI LINAC. This cold moderator proved to easily and safely couple to an existing neutron producing target, while enhancing neutron flux below 0.02 eV by cooling polyethylene down to 29 K. This cold moderator capability allowed for significantly improved counting statistics below 0.02 eV not previously possible due to a poor signal to background ratio. Additionally, testing was performed to characterize the energy resolution of the new cold moderator system and found the system easily capable of resolving resonances in Ta-181 at 4 and 10 eV, while also clearly resolving the Bragg edges found in Be metal below 0.01 eV. Following the design and development of a cold polyethylene moderator, a series of thermal total cross section measurements were performed for polyethylene, polystyrene, Plexiglas and yttrium hydride in the thermal region. These measurements serve to help validate thermal scattering law (TSL) evaluations in the 0.0006 – 20 eV energy range. For polyethylene and polystyrene, two sets of experiments were performed – one with the Enhanced Thermal Target (ETT) and another with the ETT plus the new cold moderator capability (ETTC). The yttrium hydride and Plexiglas measurements were only performed with the ETTC. The measurements for polyethylene help to validate the data processing methodology when using the ETTC, while extending the measured range of polyethylene down to 0.0007 eV. Two different Plexiglas, Plexiglas G and Plexiglas G-UVT, and two different concentrations of yttrium hydride, H/Y = 1.85 and 1.68, were measured. Overall, all materials had generally good agreement with their ENDF/B-VIII.0 TSL evaluations, though some discrepancies were noticed. In the case of the yttrium hydride, the high energy oscillations in the hydrogen cross section and the low energy Bragg edges in the yttrium cross section were clearly seen. These measurements represent the first total cross section measurements that encompass the entire thermal region from 0.0006 – 3 eV for polystyrene and yttrium hydride.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

TRACG benchmark study: 2015 Fermi thermal-hydraulic instability event

On March 19, 2015, the Boiling Water Reactor (BWR) Fermi 2 (referred to hereafter as Fermi), located in Michigan, U.S., experienced a scram initiated by the Oscillation Power Range Monitor (OPRM) system. The plant had been operating in Single Loop Operation (SLO) for approximately 10 minutes before the scram occurred. During this time, the plant operating conditions reached a region within the power/flow (P/F) map susceptible to coupled neutronic/thermal-hydraulic (T-H) instabilities. Limited code benchmarking is available in literature for T-H Instability (THI) transients occurring in plants operating at SLO conditions due to scarce plant data for this type of operational condition. This study aims to model and benchmark the THI event at SLO conditions using TRACG, the GE Hitachi (GEH) proprietary best-estimate transient system code. The TRACG model was benchmarked by comparing the results with measured plant data, such as the total reactor power and core flow, from the event. Additionally, to evaluate the inherent stability of the plant at different P/F points, Decay Ratio (DR) calculations were performed. The capability of TRACG for calculating DRs is well documented, and it has also been approved by the U.S. Nuclear Regulatory Commission (NRC) as part of ESBWR TRACG stability licensing topical reports. The results of TRACG DRs were compared to the GEH best-estimate frequency domain code ODYSY, which is the current Fermi licensing basis code for reload analysis DR calculations.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1988

Multi-body aircraft with an all-movable center fuselage actively controlling fuselage pressure drag

A multi-body aircraft with an all-movable center fuselage which translates relative to two side fuselages is described. At subsonic and transonic flight the center fuselage is in a forward position. At supersonic speeds the center fuselage moves aft so as to ensure optimum aerodynamic interference at particular Mach numbers. This provides an increased shock strength and greater surface areas so the significant reductions in zero-lift wave drag can be achieved. This concept allows for a significant increase in the wing aspect ratio which would improve high-lift performance at all speeds without incurring a significant supersonic zero-lift wave drag penalty. In addition to an improved low-fineness ratio, high-speed performance is achieved at all speeds and for all flight conditions.

Wood, Richard M.↗
DOE OSTI2020

The effect of lighting environment on task performance in buildings – A review

The effects of indoor environmental conditions on human health, satisfaction, and performance have been the focal point of research for decades. This paper reviews and summarizes the impact of lighting environment on task performance, specifically for the built environment audience. Existing studies included a variety of performance tests on cognitive performance and perception, visual acuity and reaction, memory, reasoning, and labor productivity. Illuminance, luminance ratio and correlated color temperature were found to affect performance in different ways, reflecting the impact of experimental techniques, conditions, performance evaluation methods used and data analysis methods. These were reviewed and categorized, with discussion on limitations related to sample size, modeling approach, carryover effects and other factors affecting individual differences in performance, with recommendations for future improvement. Although no universal conclusions can be made, in general, task performance seems to improve with higher illuminances, contrast ratios in the range of 7–11:1 (while always making sure that glare will not occur in the space) and higher correlated color temperature, while spectral tuning in the red or blue wavelengths has also shown positive effects. To obtain more generic evidence, future studies should be more consistent in terms of experimental procedures and overall light conditions, and also consider the effects of vertical illuminance, daylight provision/control, and outside views on task performance. Finally, studying performance with multi-factorial designs in a human-centered optimized manner (such as deploying variable lighting scenarios optimized for various tasks) can lead to deeper understanding of lighting effects on task performance, and ultimately to improved lighting design and operation in buildings overall.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

TU-F-CAMPUS-I-05: Investigation of An EMCCD Detector with Variable Gain in a Micro-CT System

Purpose: To investigate the performance of a newly built Electron Multiplying Charged Coupled Device (EMCCD) based Micro-CT system, with variable detector gain, using a phantom containing contrast agent of different concentrations. Methods: We built a micro- CT system with an EMCCD having 8 microns pixels and on-chip variable gain. We tested the system using a phantom containing five tubes filled with different iodine contrast solutions (30% to 70%). First, we scanned the phantom using various x-ray exposures values at 40 kVp and constant detector gain. Next, for the same tube currents, the detector gain was increased to maintain the air value of the projection image constant. A standard FDK algorithm was used to reconstruct the data. Performance was analyzed by comparing the signal-to-noise ratio (SNR) measurements for increased gain with those for the low constant gain at each exposure. Results: The high detector gain reconstructed data SNR was always greater than the low gain data SNR for all x-ray settings and for all iodine features. The largest increases were observed for low contrast features, 30% iodine concentration, where the SNR improvement approached 2. Conclusion: One of the first implementations of an EMCCD based micro- CT system was presented and used to image a phantom with various iodine solution concentrations. The analysis of the reconstructed volumes showed a significant improvement of the SNR especially for low contrast features. The unique on-chip gain feature is a substantial benefit allowing the use of the system at very low x-ray exposures per frame.Partial support: NIH grant R01EB002873 and Toshiba Medical Systems Corp. Partial support: NIH grant R01EB002873 and Toshiba Medical Systems Corp.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1984

The dynamics and control of large flexible space structures, part 7

A preliminary Eulerian formulation of the in-plane dynamics of the proposed spacecraft control laboratory experiment configuration is undertaken when the mast is treated as a cantilever type beam and the reflector as a lumped mass at the end of the beam. Frequency and mode shapes are obtained for the open loop model of the beam system and the stability of closed loop control systems is analyzed by both frequency and time domain techniques. Environmental disturbances due to solar radiation pressure are incorporated into models of controlled large flexible orbiting platforms. Thermally induced deformations of simple beam and platform type structures are modelled and expressions developed for the disturbance torques resulting from the interaction of solar radiation pressure. Noise effects in the deterministic model of the hoop/column antenna system are found to cause a degradation in system performance. Appropriate changes in the ratio of plant noise to the measurement noise and/or changes in the control weighting matrix elements can improve transient and steady state performance.

Bainum, P. M.↗
DOE OSTI2018

Influence of propylene glycol/nitrates ratio on microwave-assisted combustion synthesis of CuO-ZnO-Al2O3 nanocatalyst: Structural and catalytic properties toward hydrogen production from methanol

Highlights: • Applicability of propylene glycol in synthesis of CuO/ZnO/Al{sub 2}O{sub 3} via combustion method. • Addressing the influence of fuel to nitrates ratio on catalytic properties and performance. • Synthesis of stable and active CuO/ZnO/Al{sub 2}O{sub 3} nanocatalyst in methanol to hydrogen. • Achievement of complete conversion at 260 °C by choosing appropriate amount of fuel. • Decrease of CO production by applying suitable fuel/nitrates ratio. - Abstract: A series of CuO-ZnO-Al{sub 2}O{sub 3} nanocatalysts were fabricated by microwave-assisted combustion method to investigate the role of propylene glycol/nitrates ratio. XRD, FESEM, FTIR, EDX, BET and TG techniques were applied to study the physicochemical properties of prepared nanocatalysts. It was found that increasing of fuel/nitrates ratio decreased the specific surface area due to incomplete combustion reaction. TG and FTIR results proved that some combustion residuals such as nitrate species and propylene glycol remained in fabricated samples and their amount increased by increasing of fuel/nitrates ratio. Also, higher dispersion of CuO crystallites as the major active sites of steam methanol reforming achieved by CZA(PG/N = 1). So, it reached the complete conversion of methanol at lower temperature compared to the other samples. The synthesized sample with propylene glycol to nitrates ratio of 1 showed high stability during 1200 min. Moreover, the deactivation study was performed on best and worst synthesized nanocatalysts.

36 MATERIALS SCIENCE↗
NASA NTRS1985

The C-12/C-13 isotope ratio toward Zeta Ophiuchi

Observations of interstellar CH(+) toward Zeta Oph were performed to determine the C-12/C-13 isotope ratio in this diffuse cloud. The very high signal-to-noise ratio spectra yield 6 sigma detections of the (C-13)H(+) features at 4232 A and 3957 A; a weighted mean C-12/C-13 ratio of 43 + or - 6 (1 sigma) is obtained. The uncertainty includes the contribution of continuum placement errors, statistical channel-to-channel signal fluctuations, and the error introduced in deconvolving the blended isotopic lines at 4232 A. This result indicates a decrease in the local galactic C-12/C-13 ratio by a factor of 2 during the 4.6 billion yr since the formation of the sun.

Hawkins, I.↗
DOE OSTI2025

Organic Electrochemical Transistor Channel Materials: Copolymerization Versus Physical Mixing of Glycolated and Alkoxylated Polymers

Organic electrochemical transistors (OECTs) feature a polymer channel capable of conducting both ions and electronic charges. The choice of the channel material is critical for OECT performance. Many efforts have focused on improving performance via the chemical tunability of conjugated polymers – through backbone, side chain, and molar mass engineering – leading to useful design principles for accumulation-mode OECT materials. However, tuning the chemical structure of conjugated polymers often requires time-consuming optimization of the synthesis route. Meanwhile, variations in molar mass, dispersity, structural defects, and metal content present challenges when attempting to analyze the detailed effects of structural modifications, as multiple performance-determining factors are often (unintentionally) changed at the same time. Therefore, this study explores blended channel materials obtained by physically mixing glycolated and alkoxylated polymers in different ratios, and compares their OECT performance with the corresponding statistical copolymers. It is shown that mixing two well-performing materials creates blends that enable rational tuning of the transistor properties without compromising on performance. Thus, channels based on blends of alkoxylated and glycolated polymers hold promise for OECT technology with tailored response, as only two materials are needed to achieve any desired side chain ratio, simplifying the optimization of OECT characteristics.

copolymerization↗
DOE OSTI2018

In-Operando Evaluation of Solid Oxide Fuel Cell (SOFC) Cathodes for Enhanced Oxygen Reduction Reaction (ORR) Activity and Durability

Through this project we developed a new in-operando 18 O-isotope exchange technique, and determined the oxygen reduction reaction (ORR) kinetics and mechanisms in various solid oxide fuel cell (SOFC) cathodes under real operating conditions of applied voltage. We were able to measure and determine oxygen surface exchange coefficients of labeled oxygen with La 0.8 Sr 0.2 MnO 3 (LSM), La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) and other cathode material samples with varying compositions. We related the cell polarization conditions to the surface exchange process and surface exchange coefficient, and suggested a model to describe this relation. Our findings imply that LSCF keeps its higher exchange rate performance over LSM under real operating conditions. Changing the A-site cation ratio in LSM can enhance its performance, especially under cathodic polarizations larger than -400mV. Cathode powder composites of LSM and LSCF with YSZ and GDC show lower exchange coefficient values under applied polarization compared to the single constituent powder samples, probably due to limited contact between the powder particles. Using our model and basic electrochemical properties of the cathode materials we are able to successfully predict the exchange kinetic properties of SOFC cathode material under real operating conditions of applied voltage / current from surface exchange coefficients obtained in the absence of an applied bias.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Numerical and experimental analysis of precooled desiccant system

This paper presents a numerical and experimental study of four novel, desiccant air-conditioning systems based on pre-cooling of the ambient air. The purpose of the study is to: 1) establish which configuration is most profitable for the future studies through numerical and experimental methods; 2) verify the concept of precooled system and confirm that it is working in experimental conditions (for this purpose two prototypes of evaporative cooling units were developed and compared for different operation arrangements with desiccant wheel); 3) Analyze practical aspects of the systems, which includes water consumption analysis, economic analysis and establishing operational modes during a cooling season in temperate climate conditions (the proposed solution has a significant advantage during operation in a temperate climate, since it can utilize its first evaporative cooler the only source of cooling energy when the humidity of outdoor air allows to to meet the latent cooling load). Four arrangements of the system with different dew point evaporative air cooler prototypes were selected and developed for comparative analysis. The system was simulated as a whole, also, each component was individually tested on measurement station. develop the optimal arrangement of the system through numerical and experimental analysis. Four different performance indicators were considered: thermal COP (Coefficient Of Performance), the ERR (Energy Efficiency Ratio), coefficient a describing the potential in compensating indoor cooling loads, water consumption ratio. Also costs of the systems were compared through economic analysis. It was established that arrangement which is characterized by best-averaged performance in terms of all considered factors is a unit combined with two different types of evaporative coolers (marked as System B)- this is caused by the favorable arrangement of two units, where one is better suited to the pre-cooler role, while the other is better suited as the post-cooler.

42 ENGINEERING↗
DOE OSTI2022

Polymer-Stabilized Liquid Metal Nanoparticles as a Scalable Current Collector Engineering Approach Enabling Lithium Metal Anodes

Dendrites and dead lithium formation over prolonged cycling have long been challenges that hinder the safe implementation of metallic Li anodes. In this study, we employ polymer-stabilized liquid metal nanoparticles (LM-P NPs) of eutectic gallium indium (EGaIn) to create uniform Li nucleation sites enabling homogeneous lithium electrodeposition. Block copolymers of poly(ethylene oxide) and poly(acrylic acid) (PEO-b-PAA) were grafted onto the EGaIn surface, forming stabilized, well-dispersed NPs. Using a scalable spray coating approach, LM-P NPs were fabricated on copper current collectors, providing lithiophilic PEO sites and interactive carboxyl groups to guide Li deposition. The Li-EGaIn alloying process greatly reduced the Li + diffusion barrier, enabling fast Li transport through the coating layer, resulting in decreased nucleation overpotential. Therefore, about five times lower Li nucleation overpotential was obtained on the LM-P modified Cu with an optimal composition of the polymers than the bare Cu substrates. DFT computations was used to reveal the binding properties between the LM-P layer and Li. Due to the regulated Li plating/stripping process, as-obtained 30 μm Li anodes paired with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM8 11 ) with a negative/positive electrode capacity (N/P) ratio ~ 10 exhibited stable cycling performance at 0.5C for over 250 cycles, with an average Coulombic efficiency of 99.55%. Ultrathin Li (1 μm) anodes with an N/P ratio ~ 0.6 were also demonstrated in Li|LiFePO 4 cells, which examined the stabilization of Li by LM-P NPs and monitored practical loadings of Li anodes that are close to anode-free systems.

25 ENERGY STORAGE↗
NASA NTRS1974

Aerodynamic performance of 0.5 meter-diameter, 337 meter-per-second tip speed, 1.5 pressure-ratio, single-stage fan designed for low noise aircraft engines

Overall and blade-element aerodynamic performance of a 0.271-scale model of QF-1 are presented, examined, and then compared and evaluated with that from similar low noise fan stage designs. The tests cover a wide range of speeds and weight flows along with variations in stator setting angle and stator axial spacing from the rotor. At design speed with stator at design setting angle and a fixed distance between stage measuring stations, there were no significant effects of increasing the axial spacing between rotor stator from 1.0 to 3.5 rotor chords on stage overall pressure ratio, efficiency or stall margin.

Gelder, T. F.↗