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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 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Pd nanoparticles on ZnO-passivated porous carbon by atomic layer deposition: an effective electrochemical catalyst for Li-O 2 battery

Uniformly dispersed Pd nanoparticles on ZnO-passivated porous carbon were synthesized via an atomic layer deposition (ALD) technique, which was tested as a cathode material in a rechargeable Li-O-2 battery, showing a highly active catalytic effect toward the electrochemical reactions-in particular, the oxygen evolution reaction. Transmission electron microscopy (TEM) showed discrete crystalline nanoparticles decorating the surface of the ZnO-passivated porous carbon support in which the size could be controlled in the range of 3-6 nm, depending on the number of Pd ALD cycles performed. X-ray absorption spectroscopy (XAS) at the Pd Kedge revealed that the carbon-supported Pd existed in a mixed phase of metallic palladium and palladium oxide. The ZnO-passivated layer effectively blocks the defect sites on the carbon surface, minimizing the electrolyte decomposition. Our results suggest that ALD is a promising technique for tailoring the surface composition and structure of nanoporous supports for Li-O-2 batteries.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Phase-space entropy cascade and irreversibility of stochastic heating in nearly collisionless plasma turbulence

We consider a nearly collisionless plasma consisting of a species of “test particles” in one spatial and one velocity dimension, stirred by an externally imposed stochastic electric field—a kinetic analog of the Kraichnan model of passive advection. The mean effect on the particle distribution function is turbulent diffusion in velocity space—known as stochastic heating. Accompanying this heating is the generation of fine-scale structure in the distribution function, which we characterize with the collisionless (Casimir) invariant C 2 ∝ ∫ ∫ d x d v 〈 f 2 〉 —a quantity that here plays the role of (negative) entropy of the distribution function. We find that C 2 is transferred from large scales to small scales in both position and velocity space via a phase-space cascade enabled by both particle streaming and nonlinear interactions between particles and the stochastic electric field. We compute the steady-state fluxes and spectrum of C 2 in Fourier space, with k and s denoting spatial and velocity wave numbers, respectively. In our model, the nonlinearity in the evolution equation for the spectrum turns into a fractional Laplacian operator in k space, leading to anomalous diffusion. Whereas even the linear phase mixing alone would lead to a constant flux of C 2 to high s (towards the collisional dissipation range) at every k , the nonlinearity accelerates this cascade by intertwining velocity and position space so that the flux of C 2 is to both high k and high s simultaneously. Integrating over velocity (spatial) wave numbers, the k -space ( s -space) flux of C 2 is constant down to a dissipation length (velocity) scale that tends to zero as the collision frequency does, even though the rate of collisional dissipation remains finite. The resulting spectrum in the inertial range is a self-similar function in the ( k , s ) plane, with power-law asymptotics at large k and s . Our model is fully analytically solvable, but the asymptotic scalings of the spectrum can also be found via a simple phenomenological theory whose key assumption is that the cascade is governed by a “critical balance” in phase space between the linear and nonlinear timescales. We argue that stochastic heating is made irreversible by this entropy cascade and that, while collisional dissipation accessed via phase mixing occurs only at small spatial scales rather than at every scale as it would in a linear system, the cascade makes phase mixing even more effective overall in the nonlinear regime than in the linear one. Published by the American Physical Society 2024

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Improving Process Level Understanding of Boundary Layer Winds over the Northeast U.S. Shelf: The Third Wind Forecast Improvement Project (WFIP3)

The third Wind Forecast Improvement Project (WFIP3), a U.S. Department of Energy and National Oceanic and Atmospheric Administration sponsored investigation, sought to improve understanding of the physical phenomena in the atmosphere and ocean that dictate the structure and variability of wind and thermodynamic fields within the marine atmospheric boundary layer. WFIP3 focused on mesoscale and submesoscale flows -- including sea breezes, low-level jets, low-level clouds, and coastal storms -- and the ability of advanced numerical model parameterizations to represent them within fully coupled oceanic and atmospheric modeling systems and foundational weather forecast models. WFIP3 conducted a comprehensive 18-month observational study over the Northeast U.S. outer continental shelf, a high-use coastal zone, using a 3D multiscale sensor array to highly resolve the temporal, vertical, and horizontal structure of the coupled atmospheric and oceanic boundary layers. Multiple land-based study sites adjacent to the coastal ocean observed surface meteorology and vertical profiles of atmospheric properties via passive infrared and microwave radiometers, active lidars and radars, and radiosondes. At sea, an array of surface flux buoys and two vertical profiling lidar buoys observed both atmospheric and oceanic properties, augmented by land-based oceanographic radar systems and routine ship-based surveys. Intensive observations of the marine atmospheric boundary layer over the ocean was done from an air-sea interaction flux tower and extended deployments of a large autonomous barge platform. Numerous critical forecasting phenomena were observed that are being evaluated within regional coupled and uncoupled modeling systems, including the National Oceanic and Atmospheric Administration's foundational High-Resolution Rapid Refresh forecast model.

Kirincich, Anthony↗
DOE OSTI2019

Experimental and Computational Analysis of NEAMS Pebble Bed Reactors

The Advanced High-Temperature Pebble Bed Reactor concept leverages a particle-based fuel format consisting of discrete spherical graphite pebbles arrayed in a packed bed architecture. Thermal regulation achieved via flow of gas (e.g., helium) or liquid (e.g., molten salt) coolants through the void spaces between pebbles in the bed (characteristic pebble diameters: ~ 6 cm, gas cooled; ~ 3 cm, liquid cooled). This design is of interest owing to inherent advantages including passive safety features and highly efficient heat transfer characteristics that enable high power densities to be achieved. Fully leveraging these advantages requires a fundamental understanding of the complex coolant flow structure within the pebble-shaped fuel bed. Unfortunately, complexities associated with non-invasively probing the micro-scale flow phenomena within the complex network of void spaces between pebbles have hindered efforts to characterize the underlying transport phenomena. Without this fundamental foundation, it becomes challenging to rationally construct macroscopic transport models based upon volume averages of micro-scale parameters that accurately capture the observed flow behavior. Consequently, this lack of fundamental knowledge has limited previous work to coarse comparisons between theory and extremely limited experimental data. Moreover, these comparisons have been made only in terms of integral or macroscopic results. Therefore, multipoint measurements with a high level of spatial and temporal resolution are critically needed to fully map the complex flow patterns and to provide data at high spatial density to permit accurate volume averaging in the pebble bed. For this project, we performed a coordinated experimental and computational effort to quantitatively map the full-field velocity and temperature fields in the interstitial spaces within the pebble bed. The major accomplishments of this project included the important knowledge acquired for the flow mixing and heat transfer in the interstitial pore scales, the effects of flow mixing in the near-wall and far-wall regions, and the by-pass flows of pebble bed systems. The produced high-resolution experimental data (not broadly available in existing literature) were then used for the numerical studies enabling the refinement and validation of standard simulation tools (Nek5000).

42 ENGINEERING↗
DOE OSTI2026

Improving High Resolution Offshore Wind Resource Assessments and Forecasts using Observations in the MA/RI Lease Areas

The third Wind Forecast Improvement Project (WFIP3) sought to improve understanding of the physical phenomena in the atmosphere and ocean that dictate the structure and variability of wind and thermodynamic fields within the Marine Atmospheric Boundary Layer (MABL). WFIP3 conducted a comprehensive 18-month observational study over the Northeast U.S. outer continental shelf, a high use coastal zone, using a 3-D multiscale sensor array to highly resolve the temporal, vertical, and horizontal structure of the coupled atmospheric and oceanic boundary layers. Multiple land-based study sites adjacent to the coastal ocean observed surface meteorology and vertical profiles of atmospheric properties via passive infrared and microwave radiometers, active lidars and radars, and radiosondes. At sea, an array of surface flux buoys and two vertical profiling lidar buoys observed both atmospheric and oceanic properties, augmented by land-based oceanographic radar systems and routine ship-based surveys. Intensive observations of the MABL over the ocean was done from an air-sea interaction flux tower and extended deployments of a large barge platform. WFIP3 focused on mesoscale and sub-mesoscale flows -- including sea breezes, low-level jets, low-level clouds, and coastal storms -- and the ability of advanced numerical model parameterizations to represent them within fully coupled oceanic and atmospheric modeling systems and foundational weather forecast models. Numerous critical forecasting phenomena were observed, however the project was terminated prior to the completion of the field observational period and the analysis period.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1975

Lightweight fuel cell powerplant for Tug

The design and characteristics of a lightweight powerplant based on advanced cell technology to meet the requirements of the Space Tug are described. The powerplant can be operated off low-pressure hydrogen and oxygen rocket propellant tanks and avoid the need for a dedicated reactant supply. Product water can be condensed or not, depending on vehicle or payload requirements. The heart of the unit, the fuel cell power section, consist of lightweight, series-connected, alkaline cells, while the power section contains accessory components for reactant conditioning, distribution, and venting, coolant circulation, passive product water removal and electric control. The proposed design offers at least a 50 per cent saving in powerplant weight, so that the total estimated powerplant dry weight including structure, tubing, wiring, interface connectors, and interface heat exchanger is 48 lb.

Handley, L. M.↗
NASA NTRS1988

Multitemperature Cryogenic Radiative Cooler

Multiple radiator stages separated by V-groove shields protect main cooler from parasitic heat radiation and offer usable cooling themselves. Proposed cryogenic radiative cooler achieves lower temperatures previously possible with passive radiators in space. Provides useful cooling power at several temperatures instead of one. Cold-radiator stage protected by multiple shield assemblies intercepting radiation heat leaks from warmer supporting structure and redirects it out to space. Each shield assembly has effective cooling capacity enabling it to cool optical filter.

Bard, Steven↗
NASA NTRS2002

Thermal Examination of an Orbiting Cryogenic Fuel Depot

For many years NASA has been interested in the storage and transfer of cryogenic fuels in space. Lunar, L2 and other chemical propulsive space vehicle missions now have staged refueling needs that a fuel depot would satisfy. The depot considered is located in lower earth orbit. Many considerations must go into designing and building such a station. Multi-layer insulation systems, thermal shielding and low conductive structural supports are the principal means of protecting the system from excessive heat loss due to boiloff. This study focuses on the thermal losses associated with storing LH2 in a passively cooled fuel depot in a lower earth equatorial orbit. The corresponding examination looks at several configurations of the fuel depot. An analytical model has been developed to determine the thermal advantages and disadvantages of three different fuel depot configurations. Each of the systems consists of three Boeing rocket bodies arranged in various configurations. The first two configurations are gravity gradient stabilized while the third one is a spin-stabilized concept. Each concept was chosen for self-righting capabilities as well as the fuel settling capabilities, however the purpose of this paper is to prove which of the three concepts is the most efficient passively cooled system. The specific areas to be discussed are the heating time from the fusion temperature to the vaporization temperature and the amount of boiloff for a specific number of orbits. Each of the previous points is compared using various sun exposed surface areas of the tanks.

Hull, Patrick V.↗
NASA NTRS2005

The Interstellar Conspiracy

If we were designing a human-carrying starship that could be launched in the not-too-distant future, it would almost certainly not use a warp drive to instantaneously bounce around the universe, as is done in Isaac Asimov's classic Foundation series or in episodes of Star Trek or Star Wars. Sadly, those starships that seem to be within technological reach could not even travel at high relativistic speeds, as does the interstellar ramjet in Poul Anderson's Tau Zero. Warp-speeds seem to be well outside the realm of currently understood physical law; proton-fusing ramjets may never be technologically feasible. Perhaps fortunately in our terrorist-plagued world, the economics of antimatter may never be attractive for large-scale starship propulsion. But interstellar travel will be possible within a few centuries, although it will certainly not be as fast as we might prefer. If humans learn how to hibernate, perhaps we will sleep our way to the stars, as do the crew in A. E. van Vogt's Far Centaurus. However, as discussed in a landmark paper in The Journal of the British Interplanetary Society, the most feasible approach to transporting a small human population to the planets (if any) of Alpha Centauri is the worldship. Such craft have often been featured in science fiction. See for example Arthur C. Clarke's Rendezvous with Rama, and Robert A. Heinlein's Orphans of the Sky. Worldships are essentially mobile versions of the O Neill free-space habitats. Constructed mostly from lunar and/or asteroidal materials, these solar-powered, multi-kilometer-dimension structures could house 10,000 to 100,000 humans in Earth-approximating environments. Artificial gravity would be provided by habitat rotation, and cosmic ray shielding would be provided by passive methods, such as habitat atmosphere and mass shielding, or magnetic fields. A late 21st century space-habitat venture might support itself economically by constructing large solar-powered satellites to beam energy back to Earth.

Johnson, Les↗
NASA NTRS2005

Rendezvous and Proximity Operations of the Space Shuttle

Space Shuttle rendezous missions presented unique challenges that were not fully recognized when the Shuttle was designed. Rendezvous targets could be passive (i.e., no lights or transponders), and not designed to facilitate Shuttle rendezvous, proximity operations and retrieval. Shuttle reaction control system jet plume impingement on target spacecraft presented induced dynamics, structural loading and contamination concerns. These issues, along with limited forward reaction control system propellant, drove a change from the Gemimi/Apollo coelliptic profile heritage to a stable orbit profile, and the development of new proximity operations techniques. Multiple scientific and on-orbit servicing missions and crew exchange, assembly and replinishment flights to Mir and to the International Space Station drove further profile and piloting technique changes, including new relative navigation sensors and new computer generated piloting cues.

Goodman, John L.↗
NASA NTRS2005

Rendezvous and Proximity Operations of the Space Shuttle

Space Shuttle rendezvous missions present unique challenges that were not fully recognized when the Shuttle was designed. Rendezvous targets could be passive (i.e., no lights or transponders), and not designed to facilitate Shuttle rendezvous, proximity operations, and retrieval. Shuttle reaction control system jet plume impingement on target spacecraft presented induced dynamics, structural loading, and contamination concerns. These issues, along with limited reaction control system propellant in the Shuttle nose, drove a change from the legacy Gemini/Apollo coelliptic profile to a stable orbit profile, and the development of new proximity operations techniques. Multiple scientific and on-orbit servicing missions, and crew exchange, assembly and replenishment flights to Mir and to the International Space Station drove further profile and piloting technique changes. These changes included new proximity operations, relative navigation sensors, and new computer generated piloting cues. However, the Shuttle's baseline rendezvous navigation system has not required modification to place the Shuttle at the proximity operations initiation point for all rendezvous missions flown.

Goodman, John L.↗
NASA NTRS2007

Programmable Thermostats for MPLM Shell Heater Control ULF1: Thermal Performances - 1

The Multi-Purpose Logistics Module (MPLM) is the primary carrier for "pressurized" logistics to and from the International Space Station (ISS). The MPLM is transported in the payload bay of the Space Shuttle and is docked to the ISS for unloading, and reloading, of contents within the ISS shirt sleeve environment. Foil heaters, controlled originally with bi-metallic thermostats, are distributed across the outside of the MPLM structure and are utilized to provide energy to the structure to avoid exposure to cold temperatures and prevent condensation. The existing bi-metallic, fixed temperature set point thermostats have been replaced with Programmable Thermostats Modules (PTMs) in the Passive Thermal Control Subsystem (PTCS) 28Vdc shell heater circuits. The goal of using the PTM thermostat is to improve operational efficiency of the MPLM on-orbit shell heaters by providing better shell temperature control via feedback control capability. Each heater circuit contains a programmable thermostat connected to an external temperature sensor, a Resistive Temperature Device (RTD), which is used to provide continuous temperature monitoring capability. Each thermostat has programmable temperature set points and control spans. The data acquisition system uses a standard RS-485 serial interface communications cable to provide digital control capability. The PTM system was designed by MSFC, relying upon ALTEC support for their integration within the MPLM system design, while KSC performed the installation and ground checkout testing of the thermostat and RS-485 communication cable on the MPLM FM1 flight module. The PTMs were used for the first time during the STS-121/ULF1.1 mission. This paper will describe the design, development and verification of the PTM system, as well as the PTM flight performance and comparisons with SINDA thermal model predictions.

Glasgow, Shaun↗
NASA NTRS2018

The Global Precipitation Measurement (GPM) Mission's Scientific Achievements and Societal Contributions: Reviewing Four Years of Advanced Rain and Snow Observations

Precipitation represents a life-critical energy and hydrologic exchange between the Earth’s atmosphere and its surface. As such, knowledge of where, when, and how much rain and snow falls is essential for scientific research and societal applications. Building on the 17-year success of the Tropical Rainfall Measurement Mission (TRMM), the Global Precipitation Measurement (GPM) Core Observatory (GPM-CO) is the first U.S. National Aeronautical and Space Administration (NASA) satellite mission specifically designed with sensors to observe the structure and intensities of both rain and falling snow. The GPM-CO has proved to be a worthy successor to TRMM, extending and improving high-quality active and passive microwave observations across all times of day. The GPM-CO launched in early 2014, is a joint mission between NASA and the Japanese Aerospace Exploration Agency (JAXA), with sensors that include the NASA-provided GPM Microwave Imager and the JAXA-provided Dual-frequency Precipitation Radar. These sensors were devised with high accuracy standards enabling them to be used as a reference for inter-calibrating a constellation of partner satellite data. These intercalibrated partner satellite retrievals are used with infrared data to produce merged precipitation estimates at temporal scales of 30 minutes and spatial scales of 0.1° x 0.1°. Precipitation estimates from the GPM-CO and partner constellation satellites, provided in near real time and later reprocessed with all ancillary data, are an indispensable source of precipitation data for operational and scientific users. Advances have been made using GPM data, primarily in improving sensor calibration, retrieval algorithms, and ground validation measurements, and used to further our understanding of the characteristics of liquid and frozen precipitation and the science of water and hydrological cycles for climate/weather forecasting. These advances have extended to societal benefits related to water resources, operational numerical weather prediction, hurricane monitoring, prediction, and disaster response, extremes, and disease.

Applications↗
DOE OSTI2023

High absorption photovoltaic material and methods of making the same

A high absorption photovoltaic material and method of making the material for use in a solar cell are disclosed. The photovoltaic material includes a surface modified with a layer of repeating photonic crystal structures. The photonic crystal structures are approximately inverse conically shaped and have a curved sidewall that has an approximately Gaussian shape. The photonic crystal structures generally have a high vertical depth and sidewall angle. The structures also have a gradient refractive index profile and exhibit the parallel-to-interface refraction light trapping effect. An anti-reflective coating is disposed over the photonic crystal structure layer. The photovoltaic material exhibits near unity light absorption over a broad range of visible and near infrared wavelengths and incidence angles, even at reduced thicknesses. The photovoltaic structures are formed via a combined photolithography and reactive-ion etching method at low power with a gas mixture having a high ratio of an etchant component to a passivation component.

Kuang, Ping↗
DOE OSTI2023

Purification of Lithium-Ion Battery Black Mass through Tailored Alkaline Corrosion

Obtaining high-purity material outputs is crucial to the viability of novel process aimed at direct recycling of lithium-ion batteries. Metallic impurities in recycled cathodes have been shown to inhibit performance, thereby threatening mainstream acceptance of recycled battery products. Thus, shredded black mass (BM) must be purified to remove metallic contaminants, and specifically Al and Cu originating from the electrode current collectors. We herein explore a process to ionize solid copper and aluminum to ionic form based on tailored alkaline chemistry, without incurring damage to the target cathode material (Li(NixMnyCo1-x-y)O2; NMC). Al and Cu corrosion may be enhanced through the addition of chloride salt, elevated temperatures, and the use of ultrasonication - all of which disrupt the formation of passivating films on the metallic surface, and thereby increase corrosion rate. We demonstrate optimized parameters for Al and Cu corrosion both from a kinetic and overall process cost perspective. Further, we analyze the impact of these conditions on the structural (XRD, SEM), chemical (EDS, ICP), and electrochemical (impedance, cycling, dQ/dV) properties of NMC, and suggest that the present purification method does not significantly disrupt NMC performance. Finally, we present preliminary results from a promising bench-scale demonstration of this purification process applied to a simulated black mass.

ADVANCED PROPULSION SYSTEMS,ENERGY STORAGE↗
DOE OSTI2011

Low interfacial trap density and sub-nm equivalent oxide thickness in In{sub 0.53}Ga{sub 0.47}As (001) metal-oxide-semiconductor devices using molecular beam deposited HfO{sub 2}/Al{sub 2}O{sub 3} as gate dielectrics

We investigated the passivation of In{sub 0.53}Ga{sub 0.47}As (001) surface by molecular beam epitaxy techniques. After growth of strained In{sub 0.53}Ga{sub 0.47}As on InP (001) substrate, HfO{sub 2}/Al{sub 2}O{sub 3} high-{kappa} oxide stacks have been deposited in-situ after surface reconstruction engineering. Excellent capacitance-voltage characteristics have been demonstrated along with low gate leakage currents. The interfacial density of states (D{sub it}) of the Al{sub 2}O{sub 3}/In{sub 0.53}Ga{sub 0.47}As interface have been revealed by conductance measurement, indicating a downward D{sub it} profile from the energy close to the valence band (medium 10{sup 12} cm{sup -2}eV{sup -1}) towards that close to the conduction band (10{sup 11} cm{sup -2}eV{sup -1}). The low D{sub it}'s are in good agreement with the high Fermi-level movement efficiency of greater than 80%. Moreover, excellent scalability of the HfO{sub 2} has been demonstrated as evidenced by the good dependence of capacitance oxide thickness on the HfO{sub 2} thickness (dielectric constant of HfO{sub 2}{approx}20) and the remained low D{sub it}'s due to the thin Al{sub 2}O{sub 3} passivation layer. The sample with HfO{sub 2} (3.4 nm)/Al{sub 2}O{sub 3} (1.2 nm) as the gate dielectrics has exhibited an equivalent oxide thickness of {approx}0.93 nm.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Structured large-pore foams improve thermal performance of LiMIT-style liquid lithium PFC

As magnetically confined fusion devices improve, the conditions at the walls become increasingly intense. Plasma facing components (PFCs) must withstand these extreme heat and particle loads without damage or degradation. Liquid lithium PFCs are known to be quite resilient, and the presence of lithium also serves to improve plasma properties. The liquid metal infused trench (LiMIT) concept is an open surface liquid lithium PFC design that has been tested extensively at the University of Illinois and in fusion devices around the world. LiMIT utilizes thermoelectric magnetohydrodynamics (TEMHD) to passively drive liquid lithium flow. This work demonstrates an extension of the LiMIT trench geometry to three dimensions. Additively manufactured large pore metallic foams maintain TEMHD drive while drastically improving heat flux handling and resistance to lithium dryout, a phenomenon where locally high TEMHD forces depresses the lithium level and exposes underlying solid structure. COMSOL multiphysics modeling of the system yields insight into the forces at play in dryout development, and shows the 3D structures can eliminate dryout. Here, low heat proof-of-concept experimental testing of the system matches computational results, and high heat flux electron beam tests more than double the proven operational range of a LiMIT-style PFC, to 6.8 MW m –2 , with no indications of dryout or impending damage.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗