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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 1,351 records · Page 75

All sources NASA NTRS DOE OSTI

NASA NTRS2015

Method for Ground-to-Satellite Laser Calibration System

The present invention comprises an approach for calibrating the sensitivity to polarization, optics degradation, spectral and stray light response functions of instruments on orbit. The concept is based on using an accurate ground-based laser system, Ground-to-Space Laser Calibration (GSLC), transmitting laser light to instrument on orbit during nighttime substantially clear-sky conditions. To minimize atmospheric contribution to the calibration uncertainty the calibration cycles should be performed in short time intervals, and all required measurements are designed to be relative. The calibration cycles involve ground operations with laser beam polarization and wavelength changes.

Lukashin, Constantine↗

NASA NTRS1992

HFAST - A harmonic analysis program for Stirling cycles

HFAST is a general-purpose third-order harmonic analysis and design program for predicting the cyclic-steady state thermodynamic performance of Stirling cycles. It represents the state-of-the-art results of years of research efforts at Mechanical Technology Inc. (MTI) in the development of Stirling cycle machines. The code has been extensively used at MTI to support the development of both free-piston and kinematic Stirling cycle machines. Lately, HFAST has undergone many major improvements, both in the analysis method and in the user's interface. This paper presents a brief description of the current analysis method used in HFAST.

Huang, S. C.↗

DOE OSTI2018

Controllable synthesis of CNT@ZnO composites with enhanced electrochemical properties for lithium-ion battery

Highlights: • The optimized CNT@ZnO composites deliver 709.2 mAh g{sup −1} at 100 mA g{sup −1} after 50 cycles. • The structure of CNT@ZnO composites has the advantages of both ZnO and MWCNTs. • The optimized CNT@ZnO composites are promising anode materials for LIBs. - Abstract: The design and synthesis of anode materials with novel structures are one of crucial issues for developing next-generation lithium-ion battery. In this work, carbon nanotube@zinc oxide (CNT@ZnO) composites are synthesized by a liquid-phase method using CNTs as a conductive support. The design of CNT@ZnO composites combines the advantages of both ZnO nanoparticles and CNTs. The optimized CNT@ZnO composite exhibits the superior cycling and rate performance. It could deliver a discharge capacity of 709.2 mAh g{sup −1} at 100 mA g{sup −1} after 50 cycles. The electrochemical results indicate that the as-synthesized CNT@ZnO composite is superior in enhancing the electrochemical performance of ZnO-based anode materials.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

NASA NTRS2011

An Active Broad Area Cooling Model of a Cryogenic Propellant Tank with a Single Stage Reverse Turbo-Brayton Cycle Cryocooler

As focus shifts towards long-duration space exploration missions, an increased interest in active thermal control of cryogenic propellants to achieve zero boil-off of cryogens has emerged. An active thermal control concept of considerable merit is the integration of a broad area cooling system for a cryogenic propellant tank with a combined cryocooler and circulator system that can be used to reduce or even eliminate liquid cryogen boil-off. One prospective cryocooler and circulator combination is the reverse turbo-Brayton cycle cryocooler. This system is unique in that it has the ability to both cool and circulate the coolant gas efficiently in the same loop as the broad area cooling lines, allowing for a single cooling gas loop, with the primary heat rejection occurring by way of a radiator and/or aftercooler. Currently few modeling tools exist that can size and characterize an integrated reverse turbo-Brayton cycle cryocooler in combination with a broad area cooling design. This paper addresses efforts to create such a tool to assist in gaining a broader understanding of these systems, and investigate their performance in potential space missions. The model uses conventional engineering and thermodynamic relationships to predict the preliminary design parameters, including input power requirements, pressure drops, flow rate, cycle performance, cooling lift, broad area cooler line sizing, and component operating temperatures and pressures given the cooling load operating temperature, heat rejection temperature, compressor inlet pressure, compressor rotational speed, and cryogenic tank geometry. In addition, the model allows for the preliminary design analysis of the broad area cooling tubing, to determine the effect of tube sizing on the reverse turbo-Brayton cycle system performance. At the time this paper was written, the model was verified to match existing theoretical documentation within a reasonable margin. While further experimental data is needed for full validation, this tool has already made significant steps towards giving a clearer understanding of the performance of a reverse turbo-Brayton cycle cryocooler integrated with broad area cooling technology for zero boil-off active thermal control.

Guzik, Monica C.↗

NASA NTRS1978

Orbit Transfer Vehicle (OTV) engine phase A study

Requirements for the orbit transfer vehicle engine were examined. Engine performance/weight sensitivities, the effect of a service life of 300 start/shutdown cycles between overalls on the maximum engine operating pressure, and the sensitivity of the engine design point (i.e., thrust chamber pressure and nozzle area ratio) to the performance requirements specified are among the factors studied. Preliminary engine systems analyses were conducted on the stage combustion, expander, and gas generator engine cycles. Hydrogen and oxygen pump discharge pressure requirements are shown for various engine cycles. Performance of the engine cycles is compared.

Mellish, J. A.↗

DOE OSTI2018

Building simulation: Ten challenges

Buildings consume more than one-third of the world’s primary energy. Reducing energy use and greenhouse-gas emissions in the buildings sector through energy conservation and efficiency improvements constitutes a key strategy for achieving global energy and environmental goals. Building performance simulation has been increasingly used as a tool for designing, operating and retrofitting buildings to save energy and utility costs. However, opportunities remain for researchers, software developers, practitioners and policymakers to maximize the value of building performance simulation in the design and operation of low energy buildings and communities that leverage interdisciplinary approaches to integrate humans, buildings, and the power grid at a large scale. This paper presents ten challenges that highlight some of the most important issues in building performance simulation, covering the full building life cycle and a wide range of modeling scales. In conclusion, the formulation and discussion of each challenge aims to provide insights into the state-of-the-art and future research opportunities for each topic, and to inspire new questions from young researchers in this field.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2017

Self-supported Zn/Si core-shell arrays as advanced electrodes for lithium ion batteries

Graphical abstract: Zn/Si core-shell arrays prepared by combined hydrothermal plus sputtering method show good performance with high specific capacity and excellent cycling stability. - Highlights: • Construct Zn/Si core-shell arrays via sputtering. • The Zn/Si core-shell arrays show high capacity and good cycles. • Core-shell arrays is favorable for fast ion/electron transfer. - Abstract: Silicon is considered as the most promising substitute for the commercial graphite anode of lithium ion batteries (LIBs) due to its high capacity and low working voltage. In this work, we realize the rational combination between Zn nanorods and Si forming self-supported Zn/Si core-shell arrays with the aid of hydrothermal and sputtering methods. Amorphous Si layer is well coated on the backbone of Zn nanorods with diameters of 70–80 nm. As a preliminary test, the Zn/Si core-shell arrays are used as the anode of LIBs and demonstrated with a high initial reversible capacity of 2795 mAh g{sup −1} at 0.1C, good high-rate capability with 1985 mAh g{sup −1} at 1C and stable cycling life. The good performance is due to the highly conductive Zn nanorod network and porous core-shell structure providing good mechanical support and fast transport of ions/electrons.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Stress-Tolerant Nanoporous Germanium Nanofibers for Long Cycle Life Lithium Storage with High Structural Stability

Nanowires (NWs) synthesized via chemical vapor deposition (CVD) process have demonstrated significant improvement in lithium storage performance along with their outstanding accommodation of large volume changes during charge/discharge process. Nevertheless, the NW electrodes have been only confined to research level due to the lack of scalability and severe side reactions by their high surface area. Here, we present nanoporous Ge nanofibers (NPGeNFs) having moderate nanoporosity via a combination of simple electrospinning and low energetic zincothermic reduction reaction. In contrast with the CVD assisted NW growth, our method provides high tunability of macro/microscopic morphologies such as a porosity, length, and diameter of the nanoscale 1D structures. Significantly, the customized NPGeNFs showed highly suppressed volume expansion less than 15% (for electrodes) after full lithation and excellent durability with high lithium storage performance over 500 cycles. Our approach in this work offers effective 1D nanostructuring with highly customized geometries and can be extended to other applications including optoelectronics, catalysis, and energy conversion.

1D nanostructures↗

NASA NTRS1973

High temperature, low cycle fatigue of copper-base alloys in argon. Part 3: Zirconium-copper; thermal-mechanical strain cycling, hold-time and notch fatigue results

The low-cycle fatigue characteristics of smooth bar and notched bar specimens (hourglass shape) of zirconium-copper, 1/2 Hard, material (R-2 Series) were evaluated at room temperature in axial strain control. Over the fatigue life range from about 300 to 3000 cycles the ratio of fatigue life for smooth bar to fatigue life for notched bar remained constant at a value of about 6.0. Some additional hold-time data for the R-2 alloy tested in argon at 538 C are reported. An analysis of the relaxation data obtained in these hold-time tests is also reported and it is shown that these data yield a fairly consistent correlation in terms of instantaneous stress rate divided by instantaneous stress. Two thermal-mechanical strain cycling tests were also performed using a cyclic frequency of 4.5 cycles per hour and a temperature cycling interval from 260 to 538 C. The fatigue life values in these tests were noticeably lower than that observed in isothermal tests at 538 C.

Conway, J. B.↗

NASA NTRS1988

C3 generic workstation: Performance metrics and applications

The large number of integrated dependent measures available on a command, control, and communications (C3) generic workstation under development are described. In this system, embedded communications tasks will manipulate workload to assess the effects of performance-enhancing drugs (sleep aids and decongestants), work/rest cycles, biocybernetics, and decision support systems on performance. Task performance accuracy and latency will be event coded for correlation with other measures of voice stress and physiological functioning. Sessions will be videotaped to score non-verbal communications. Physiological recordings include spectral analysis of EEG, ECG, vagal tone, and EOG. Subjective measurements include SWAT, fatigue, POMS and specialized self-report scales. The system will be used primarily to evaluate the effects on performance of drugs, work/rest cycles, and biocybernetic concepts. Performance assessment algorithms will also be developed, including those used with small teams. This system provides a tool for integrating and synchronizing behavioral and psychophysiological measures in a complex decision-making environment.

Eddy, Douglas R.↗

NASA NTRS2013

Improved Low Temperature Performance of Supercapacitors

Low temperature double-layer capacitor operation enabled by: - Base acetonitrile / TEATFB salt formulation - Addition of low melting point formates, esters and cyclic ethers center dot Key electrolyte design factors: - Volume of co-solvent - Concentration of salt center dot Capacity increased through higher capacity electrodes: - Zeolite templated carbons - Asymmetric cell designs center dot Continuing efforts - Improve asymmetric cell performance at low temperature - Cycle life testing Motivation center dot Benchmark performance of commercial cells center dot Approaches for designing low temperature systems - Symmetric cells (activated carbon electrodes) - Symmetric cells (zeolite templated carbon electrodes) - Asymmetric cells (lithium titanate/activated carbon electrodes) center dot Experimental results center dot Summary

benchmark↗

NASA NTRSDate not supplied

Exploration Extravehicular Mobility Unit (xEMU) 11 Foot Vacuum Chamber Upgrades Test Results

The Exploration Extravehicular Mobility Unit (xEMU) uncrewed 11 foot vacuum chamber testing evaluated the capabilities of the 11 foot vacuum chamber facility to support advanced spacesuit testing. The government reference design xEMU spacesuit provided a high-fidelity test article to demonstrate 11 foot vacuum chamber capabilities which included: gas loading of the chamber at varying simulated metabolic rates and open loop suit abort operations, Intravehicular Activity (IVA) vacuum access, consumables recharge, IVA vehicle-provided thermal loop cooling, and IVA vehicle-provided power. To demonstrate the xEMU airlock operations transitioning from IVA to EVA conditions without a test subject in the suit, test support equipment was developed to remotely actuate both the Exploration, Servicing, and Cooling Umbilical (ESCU) and the vacuum access umbilical. This test also evaluated the performance of the Exploration Portable Life Support System (xPLSS) at vacuum conditions. Data was collected and analyzed for carbon dioxide (CO2) scrubbing performance of the Rapid Cycle Amine (RCA) swingbed, for thermal regulation performance of the Suit Water Membrane Evaporator (SWME), and for sensor performance across the xPLSS. This paper will detail the findings of the testing performed with these upgrades which discussed previously laid out in ICES-2025-342.

Robert F Marsch↗

NASA NTRSDate not supplied

Exploration Extravehicular Mobility Unit 11 Foot Vacuum Chamber Upgrades Test Results

Robert Marsch↗

DOE OSTI2017

Economic Module Development for the Fuel Cycle Simulation Tool CLASS

An economical module to calculate the financial aspect of nuclear industry was developed based on CLASS, a library used for performing dynamic fuel cycle simulations. The tool will be introduced and a simple case of a PWR reactor will be presented to validate the module looking forward to evaluate a symbiotic scenario in the full paper involving UOX reactors, MOX reactors for recycling the plutonium and PHWR reactors for recycling the uranium.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

A novel small-molecule compound of lithium iodine and 3-hydroxypropionitride as a solid-state electrolyte for lithium–air batteries

A novel small-molecule compound of lithium iodine and 3-hydroxypropionitrile (HPN) has been successfully synthesized. Our combined experimental and theoretical studies indicated that LiIHPN is a Li-ion conductor, which is utterly different from the I–-anion conductor of LiI(HPN) 2 reported previously. Solid-state lithium–air batteries based on LiIHPN as the electrolyte exhibit a reversible discharge capacity of more than 2100 mAh g –1 with a cyclic performance over 10 cycles. Lastly, our findings provide a new way to design solid-state electrolytes toward high-performance lithium–air batteries.

25 ENERGY STORAGE↗

DOE OSTI2014

An ultra-high vacuum electrochemical flow cell for in situ/operando soft X-ray spectroscopy study

An in situ flow electrochemical cell has been designed and fabricated to allow better seal under UHV chamber thus to achieve a good signal to noise ratio in fluorescence yield detection of X-ray absorption spectra for spectroelectrochemical study. The cell also stabilizes the thin silicon nitride membrane window in an effective manner so that the liquid cell remains intact during X-ray absorption experiments. With the improved design of the liquid cell, electrochemical experiments such as cyclic voltammetry have been performed for 10 cycles with a good stability of sample window. Also an operando electrochemical experiment during photoelectrochemistry has been performed on n-type hematite electrode deposited on silicon nitride window. The experiment allows us to observe the formation of two extra electronic transitions before pre edge of O K-edge spectra.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2013

System Modeling and Building Energy Simulations of Gas Engine Driven Heat Pump

To improve the system performance of a gas engine driven heat pump (GHP) system, an analytical modeling and experimental study has been made by using desiccant system in cooling operation (particularly in high humidity operations) and suction line waste heat recovery to augment heating capacity and efficiency. The performance of overall GHP system has been simulated with a detailed vapor compression heat pump system design model. The modeling includes: (1) GHP cycle without any performance improvements (suction liquid heat exchange and heat recovery) as a baseline (both in cooling and heating mode), (2) the GHP cycle in cooling mode with desiccant system regenerated by waste heat from engine incorporated, (3) GHP cycle in heating mode with heat recovery (recovered heat from engine). According to the system modeling results, by using the desiccant system the sensible heat ratio (SHR- sensible heat ratio) can be lowered to 40%. The waste heat of the gas engine can boost the space heating efficiency by 25% at rated operating conditions. In addtion,using EnergyPlus, building energy simulations have been conducted to assess annual energy consumptions of GHP in sixteen US cities, and the performances are compared to a baseline unit, which has a electrically-driven air conditioner with the seasonal COP of 4.1 for space cooling and a gas funace with 90% fuel efficiency for space heating.

building energy simulation↗

DOE OSTI2021

Organic Solvent Free Process to Fabricate High Performance Silicon/Graphite Composite Anode

Cycling stability is a key challenge for application of silicon (Si)-based composite anodes as the severe volume fluctuation of Si readily leads to fast capacity fading. The binder is a crucial component of the composite electrodes. Although only occupying a small amount of the total composite mass, the binder has major impact on the long-term electrochemical performance of Si-based anodes. In recent years, water-based binders including styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) have attracted wide research interest as eco-friendly and low-cost alternatives for the conventional poly(vinylidene difluoride) (PVDF) binder in Si anodes. In this study, Si-based composite anodes are fabricated by simple solid mixing of the active materials with subsequent addition of SBR and CMC binders. This approach bypasses the use of toxic and expansive organic solvents. The factors of binder, silicon, and graphite materials have been systematically investigated. It is found that the retained capacities of the anodes are more than 440 mAh/g after 400 cycles. These results indicate that organic solvent free process is a facile strategy for producing high performance silicon/graphite composite anodes.

Fang, Chen (ORCID:0000000321011991)↗