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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Method for Processing Lunar Regolith Using Microwaves

A paper describes a method of using microwave heating experiments on lunar simulants to determine the mechanism that causes lunar regolith to be such an excellent microwave absorber. The experiments initially compared the effects of sharp particle edges to round particle edges on the heating curves. For most compositions, sharp particle edged samples were more effective in being heated by microwaves than round particle edged materials. However, the experiments also showed an unexpected effect for both types of particles. Upon heating the sample surface above 400 C, the sample experienced some sort of internal structure change that caused it to heat much more efficiently. This enhancement may be associated with the unique microwave volumetric heating that can produce a large temperature gradient within the sample leading to melting of some components at the center of the sample. This new effect that may also be happening in lunar regolith samples is probably the cause of the previously observed enhanced heating of a sample of lunar regolith. Properly designed microwave applicators could heat and solidify the lunar regolith to form roads and building blocks for structures needed on the Moon

Barmatz, Martin B.↗
DOE OSTI2021

Effect of temperature on abrasion erosion in particle based concentrating solar powerplants

The use of solid particles as a heat transfer medium is being explored for concentrated solar power plants (CSP) to increase their efficiency by achieving operating temperature >700 °C. During operation, these hot particles are expected to move along the various components within the collector system, resulting in material degradation from a combination of high-temperature oxidation and erosion. In the present study, the performance of candidate materials was evaluated through a series of abrasion erosion experiments at room temperature as well as at 800 °C. Wear in metallic and refractory type materials was investigated using CarboBead® HSP 40/70 particles inside a resistance heated kiln. Furthermore, cross-sectional scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analysis on the specimens tested at 800 °C determined that the specific wear rate in Inconel 740H and stainless steel 316 metallic specimens was influenced by the thermally grown oxide morphology. High chromium Inconel 740H specimens exhibited greater resistance to wear with a steady state specific wear rate of 1.92E-4 mm 3 N -1 m –1 compared to 5.7E-3 mm 3 N -1 m –1 for Stainless Steel 316.

14 SOLAR ENERGY↗
NASA NTRS1991

Heat flow between species in one-dimensional particle plasma simulations

The theory of Eldridge and Feix (1962) is presently applied to characterize the rate of heat flow between two one-dimensional particle species. Formulas derived assuming initial Maxwellian distributions, while complex, are judged applicable to simulators. Tests of the theory by simulations using Langdon and Birdsall's (1985) standard code yield results which indicate that heat flow between species may become rapid when the actual (not necessarily the intended) temperatures differ: thereby presenting a substantial hazard.

Lawson, William S.↗
DOE OSTI2025

Reirradiation and Post-reirradiation Heating Tests of Loose AGR-2 TRISO Particles and AGR-3/4 Fuel Compacts

To address the lack of data on the behavior of short-lived fission products I-131 (t1/2 = 8.02 d) and Xe-133 (t1/2 = 5.24 d) in the TRISO fuel system, loose AGR-2 particles and kernels were reirradiated in NRAD and subjected to post-reirradiation heating in the FACS furnace. This provided data on the release of fission products from exposed kernels, and the results were used to establish FACS condensation plate collection efficiencies for temperatures of 1000, 1200, and 1400°C where previously, the only collection efficiencies were for 1600°C tests. These new collection efficiencies were then applied to the NRAD-FACS tests of entire AGR-3/4 fuel compacts. Understanding the relative behavior of short-lived I-131, for example, is important because it is a significant contributor to offsite dose during postulated accidents, and Xe-133 has previously been used as a conservative indicator of I-131 behavior. These data will be used to support refinement of fission product transport models and HTGR source-term analyses.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1993

Thermal conductivity measurements of particulate materials under Martian conditions

The mean particle diameter of surficial units on Mars has been approximated by applying thermal inertia determinations from the Mariner 9 Infrared Radiometer and the Viking Infrared Thermal Mapper data together with thermal conductivity measurement. Several studies have used this approximation to characterize surficial units and infer their nature and possible origin. Such interpretations are possible because previous measurements of the thermal conductivity of particulate materials have shown that particle size significantly affects thermal conductivity under martian atmospheric pressures. The transfer of thermal energy due to collisions of gas molecules is the predominant mechanism of thermal conductivity in porous systems for gas pressures above about 0.01 torr. At martian atmospheric pressures the mean free path of the gas molecules becomes greater than the effective distance over which conduction takes place between the particles. Gas particles are then more likely to collide with the solid particles than they are with each other. The average heat transfer distance between particles, which is related to particle size, shape and packing, thus determines how fast heat will flow through a particulate material.The derived one-to-one correspondence of thermal inertia to mean particle diameter implies a certain homogeneity in the materials analyzed. Yet the samples used were often characterized by fairly wide ranges of particle sizes with little information about the possible distribution of sizes within those ranges. Interpretation of thermal inertia data is further limited by the lack of data on other effects on the interparticle spacing relative to particle size, such as particle shape, bimodal or polymodal mixtures of grain sizes and formation of salt cements between grains. To address these limitations and to provide a more comprehensive set of thermal conductivities vs. particle size a linear heat source apparatus, similar to that of Cremers, was assembled to provide a means of measuring the thermal conductivity of particulate samples. In order to concentrate on the dependence of the thermal conductivity on particle size, initial runs will use spherical glass beads that are precision sieved into relatively small size ranges and thoroughly washed.

Presley, M. A.↗
DOE OSTI2021

A Comparative Study on the Effect of Zr, Sn, and Ti on the Crystallization Behavior of Nepheline Glass

In alkali aluminosilicate glasses, additions of 4+ cations like Zr and Ti are often added to promote crystallization. In this study, Zr, Ti, or Sn are progressively substituted for Si in nepheline (NaAlSiO4) glass to determine their impact on the crystallization behavior. For glasses homogeneous on quenching, up to NaAlZr0.075Si0.925O4, NaAlSn0.100Si0.900O4, and NaAlTi0.300Si0.700O4, respectively, crystallization temperatures were investigated by thermal analysis. A subset of compositions was subjected to additional thermal analysis, varying heating rate and particle size, to investigate the subtleties of crystallization behavior. Subsequent heat treatment of glass powders was performed to maximize crystallization, and glass-ceramic microstructure was assessed by optical microscopy and electron microprobe, while crystalline phases were determined by X-ray diffraction. In all cases the major crystalline phase was orthorhombic carnegieite, which accommodated Ti in its structure but not Zr or Sn, and excess 4+ cations formed MO2, i.e., brookite, baddeleyite, and cassiterite, respectively.

Nienhuis-Marcial, Emily T.↗
DOE OSTI2022

Enhanced performance in fusion plasmas through turbulence suppression by megaelectronvolt ions

Alpha particles with energies on the order of megaelectronvolts will be the main source of plasma heating in future magnetic confinement fusion reactors. Instead of heating fuel ions, most of the energy of alpha particles is transferred to electrons in the plasma. Furthermore, alpha particles can also excite Alfvénic instabilities, which were previously considered to be detrimental to the performance of the fusion device. In this work, we report improved thermal ion confinement in the presence of megaelectronvolts ions and strong fast ion-driven Alfvénic instabilities in recent experiments on the Joint European Torus. Herein, detailed transport analysis of these experiments reveals turbulence suppression through a complex multi-scale mechanism that generates large-scale zonal flows. This holds promise for more economical operation of fusion reactors with dominant alpha particle heating and ultimately cheaper fusion electricity.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Radiant boiler for pressurized oxy-combustion and method of radiant trapping to control heat flux in high temperature particle-laden flows at elevated pressure

A boiler has a shell surrounding a vertical centerline. The shell defines an inner surface having an inner diameter and an inner length extending between an upper upstream end and a lower downstream end. The inner surface defines a hollow interior, the boiler having a pre-combustion zone, a combustion zone downstream from the pre-combustion zone, and a post-combustion zone downstream from the combustion zone. The shell is tapered outward along its length in at least a portion of the combustion zone. An oxidizer inlet is in fluid communication with the pre-combustion zone, and a fuel nozzle introduces fuel into the combustion zone. A tube assembly is mounted in the hollow interior of the shell for transferring heat to fluid flowing through the tube assembly. A flue duct is in fluid communication with the post-combustion zone for transporting flue gases from the hollow interior.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2020

Titanium-group nano-whiskers and method of production

Disclosed herein are structures comprising a titanium, zirconium, or hafnium powder particle with titanium carbide, zirconium carbide, or hafnium carbide (respectively) nano-whiskers grown directly from and anchored to the powder particle. Also disclosed are methods for fabrication of such structures, involving heating the powder particles and exposing the particles to an organic gas.

Seals, Roland D.↗
DOE OSTI2023

Titanium-group nano-whiskers and method of production

Disclosed herein are structures comprising a titanium, zirconium, or hafnium powder particle with titanium carbide, zirconium carbide, or hafnium carbide (respectively) nano-whiskers grown directly from and anchored to the powder particle. Also disclosed are methods for fabrication of such structures, involving heating the powder particles and exposing the particles to an organic gas.

Menchhofer, Paul A.↗
NASA NTRS2018

Method of Manufacturing a Humidity Sensing Material

A method is provided for manufacturing a humidity sensing material. Particles of a trivalent rare earth hydroxide or oxide (such as lanthanum hydroxide) are mixed with particles of barium oxide and titanium dioxide in specified proportions. The particle mixture is heated to generate a sintered mixture that is milled. The resulting milled particles are mixed with glass particles, an organic surfactant, a solvent, an organic vehicle, and an alkali hydroxide. The resulting liquid mixture is deposited as a layer thereof onto a substrate. The substrate and layer thereon are processed to remove liquid portions of the liquid mixture. Such liquid removal processing includes at least one cycle of heating the layer followed by a corresponding cycle of cooling the layer in a nitrogen atmosphere containing less than 25 parts per million of oxygen.

Rolin, Terry D.↗
NASA NTRS1972

Investigation of gaseous nuclear rocket technology

The experimental and theoretical investigations conducted during the period from September 1969 through September 1972 are reported which were directed toward obtaining information necessary to determine the feasibility of the full-scale nuclear light bulb engine, and of small-scale nuclear tests involving fissioning uranium plasmas in a unit cell installed in a driver reactor, such as the Nuclear Furnace. Emphasis was placed on development of RF simulations of conditions expected in nuclear tests in the Nuclear Furnace. The work included investigations of the following: (1) the fluid mechanics and containment characteristics of one-component and two-component vortex flows, both unheated and RF-induction heated; (2) heating of particle-seeded streams by thermal radiation from a dc arc to simulate propellant heating; (3) condensation and separation phenomena for metal-vapor/heated-gas mixtures to provide information for conceptual designs of components of fuel exhaust and recycle systems; (4) the characteristics of the radiant energy spectrum emitted from the fuel region, with emphasis on definition of fuel and buffer-gas region seed systems to reduce the ultraviolet radiation emitted from the nuclear fuel; and (5) the effects of nuclear radiation on the optical transmission characteristics of transparent materials.

Kendall, J. S.↗
NASA NTRS2016

Photon Doppler Velocimeter to Measure Entrained Additive Manufactured Bulk Metal Powders in Hot Subsonic and Supersonic Oxygen Gas

Parts produced by additive manufacturing, particularly selective laser melting (SLM), have been shown to silt metal particulate even after undergoing stringent precision aerospace cleaning processes (Lowrey 2016). As printed parts are used in oxygen systems with increased pressures, temperatures, and gas velocity, the risk of ignition by particle impact, the most common direct ignition source of metals in oxygen, substantially increases. The White Sands Test Facility (WSTF), in collaboration with Marshall Space Flight Center (MSFC), desires to test the ignitability of SLM metals by particle impact in heated oxygen. The existing test systems rely on gas velocity calculations to infer particle velocity in both subsonic and supersonic particle impact systems. Until now, it was not possible to directly measure particle velocity. To increase the fidelity of planned SLM ignition studies, it is necessary to validate that the Photon Doppler Velocimetry(PDV) test system can accurately measure particle velocity.

Tylka, Jonathan↗
DOE OSTI2023

Differential emissivity based evaporable particle measurement

A differential emissivity imaging device for measuring evaporable particle properties can include a heated plate, a thermal camera, a memory device, and an output interface. The heated plate can have an upper surface oriented to receive falling evaporable particles. The evaporable particles have a particle emissivity and the upper surface has a plate surface emissivity. The thermal camera can be oriented to produce a thermal image of the upper surface. A memory device can include instructions that cause the imaging device to calculate a mass of the individual evaporable particle via heat conduction using a calculated surface area and an evaporation time.

Garrett, Tim↗
NASA NTRS1990

Particle acceleration by electromagnetic ion cyclotron turbulence

The LF EM-turbulence which furnishes energy for the acceleration of ions in various regions of the earth's magnetosphere efficiently accomplishes its transfer of energy from waves to particles through ion cyclotron resonance (ICR) with the left-hand polarized component of the turbulence; the result of this interaction is a heating of the particle distribution. A general theoretical treatment of ICR heating in a weakly inhomogeneous magnetic geometry is presented, en route to a more detailed examination of auroral ion conics' formation. A substantial simplification of the analysis of the altitude-asymptotic form of the conic distribution is obtained via the similarity transformation introduced into the properties of the electric field spectral density and the earth's dipolar magnetic field.

Crew, G. B.↗
DOE OSTI2021

Measurements of scattering and absorption properties of submillimeter bauxite and silica particles

Submillimeter solid particles have been considered as thermal storage media for concentrated solar power applications. Knowledge of the scattering and absorption properties of individual particles is crucial for modeling the radiative heat transfer of the particle bed. In this work, a laser scatterometer is used to measure the single-particle scattering properties at a wavelength of 635 nm by using two configurations: (1) a falling particle curtain and (2) a taped particle layer. Because a one-particle nominal thickness is formed with area fractions of 5-55% depending on the configuration, multiple scattering is minimized and hence the single scattering phase function, averaged over all illuminated particles, is directly measured. Bauxite-based ceramic particles that are strongly absorbing in the solar spectrum and silica particles that are nonabsorbing in the visible and near-infrared are investigated. The directional-hemispherical reflectance and transmittance of the taped particles are also measured to deduce the forward and backward scattering efficiency factors and the absorption efficiency factors. Only weak wavelength dependence is observed in the measured region from 380 nm to 1020 nm. Furthermore, the scattering phase functions of all bauxite-based particles with varying sizes and compositions are very similar and can be fitted to a Henyey-Greenstein phase function with an asymmetry factor g = -0.20. For the silica particles, forward scattering dominates and g = 0.45 yields the best fit. A Monte Carlo method is developed to model the particle scattering characteristics, and reasonable agreements between the modeling and experimental results are observed by introducing a specularity parameter.

42 ENGINEERING↗
DOE OSTI2022

Convective Heat Transfer Potential of Particles/Airflow Through Single Cell Thick Additively Manufactured Octet-Shaped Lattice Frame Material

Abstract Particle-to-Supercritical Carbon Dioxide (sCO2) heat exchangers are one of the most critical components of the next-generation Concentrating Solar Power (CSP) plants. There have been several efforts to enhance the overall heat exchanger performance which essentially comprises of thermal resistances offered by sCO2 channel, wall (separating sCO2 with particles) thickness, particle-wall contact resistance and particle-side effective heat transfer coefficient. This study is focused towards reducing the particle side thermal resistance by incorporating single unit cell thick reticulated Octet lattice frame structures on the falling particle side to enhance the effective thermal conductivity of the particle channel and to enhance convective heat transfer between the falling particles and the solid phase of the falling particle channel (endwalls and fibers). Steady-state experiments were conducted to measure the effective thermal conductivity of lattice frame material for two cases: a) when void space was occupied by air, b) when void space was occupied with particles. Further, convective heat transfer experiments have been conducted with both air (steady-state) and particles (quasi steady-state) as “working fluid” for panels sandwiching the Octet array. Three different lattice porosities ranging from 0.75 to 0.9 have been tested for a wide range of air flow rates and a fixed particle flow rate (highest potential).

Aider, Youssef↗