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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Capillary Movement in Granular Beds in Microgravity

Understanding the dynamics of capillary flow through unsaturated porous media is very important for the development of an effective water and nutrient delivery system for growing plants in microgravity and chemical engineering applications. Experiments were conducted on the Space Shuttle during the STS-63 mission using three experimental cuvettes called "Capillary Testbed-M." These experiments studied the effect of bead diameter on capillary flow by comparing the capillary flow in three different granular beds. It was observed that the speed of water propagation in the granular bed consisting of 1.5 mm diameter particles was less than that in the bed consisting of 1.0 mm. diameter particles. Such results contradict the existing theory of capillary water propagation in granular beds. It was found also that in microgravity water propagates independently in adjacent layers of a layered granular bed .

Yendler, Boris S.↗
DOE OSTI2020

Exploratory investigation on the use of low-cost alternative media for ultrafine grinding of coal

In this study, the energy efficiency of three alternative grinding media including, coarse silica beads, fine silica beads, and granular sand, were evaluated and compared against standard stainless steel. Stirred mill test results show that both silica beads and granular sand were more efficient than stainless steel in producing ultrafine particles following the order of coarse silica beads>granular sand>fine silica beads>stainless steel. The finest product size corresponding to a P 80 value of 2.33 μm was generated by coarse silica beads with a nominal size of 420×1190 μm, which also consumed the least amount of grinding energy. The specific energy input was reduced by almost 50% as opposed to that of stainless steel, while the operating work index was reduced by 87%. Overall, the test data indicate that grinding media density, media particle size and shape all play a role in determining the optimized grinding behavior of the coal material.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2023

Investigation of Best-Practices and Computationally Inexpensive Radiative Exchange Models for Discrete Element Method Modeling of Aluminosilicate Particles in Concentrating Solar Power Environments

Chemically inert, aluminosilicate based particles have been investigated as both a thermal transport and sensible energy storage medium for concentrating solar power facilities. These particles will experience a wide range of operating temperatures (300-1000 K) and handling conditions (dense to dilute falling particle curtains, dense granular flows, or dense structures), requiring specially-designed and optimized infrastructures. The relative influence of collisional and frictional interactions between particles varies based on temperature-dependent particulate properties and greatly impacts the bulk, granular flow behavior. These underlying physics are captured using discrete element method modeling tools. However, this modeling method is computationally expensive as each particle position and interaction is tracked during the simulation. These modeling methods are further complicated by introducing temperature-dependent particle properties, high-temperature radiative exchange, and directional irradiation sources experienced by granular flows in concentrating solar power environments. In this study, coupled experimental and numerical slump testing of aluminosilicate particles was performed and computationally efficient radiative exchange models were evaluated to establish best-practices for discrete element method models for concentrating solar power environments. The three particle types investigated included Carbobead HSP 30 /60, Carbobead CP 30/60, and Granusil 4030. Existing modeling limitations and computationally-efficient multi-modal heat transfer models were evaluated using Aspherix®, a commercial discrete element method software. High-temperature (< 1073 K) slump testing of aluminosilicate particles was performed to investigate the deviation between experimentally-observed and numerically-predicted angles of repose introduced by computation-time reduction practices including the relaxation of the particle elastic modulus and coarse-graining. Coarse-graining is used to use a single modeled particle that is representative of a collection of smaller particles, decreasing the computational cost at the expense of geometric accuracy. Additionally, relaxation of the elastic modulus is used to reduce computational time at the expense of an increased, modeled particle overlap. Prior studies have determined that aluminosilicate particles retain a high elastic modulus at high temperatures (< 1073 K), requiring small simulation timesteps to ensure resolved contact forces resemble appropriate solid mechanics. A parametric study was performed to evaluate the influence of computation time improvements on the deviation between experimental and modeled angle of repose across high temperatures < 1073 K. Additionally, numerical case studies were performed on candidate particle systems at varying porosities and temperatures. These studies were performed to investigate the influence of computationally-efficient radiative-exchange modeling methods coupled to Aspherix® on modeled accuracy and computation time. The recently-developed distance-based approximation was evaluated in estimating radiative exchange between particles and participating surfaces located in close proximity. The distance based approximation was developed to use tabulated estimates of the radiative distribution factor between individual particles and surfaces in close proximity (< 40 particle radii). These methods were expanded to the aluminosilicate particles of interest, including the influence of particle size distributions. To capture radiative exchange between particles and surfaces not in close proximity (> 40 particle radii) and to capture the absorption of directional irradiation from concentrating solar resources, a volumetrically-averaged radiative distribution factor was calculated between the modeled granular flow and surfaces using Monte Carlo ray-tracing for participating media. Volume-averaged absorption and scattering coefficients were predicted using a volumetric discretization of the modeled domain with monodisperse approximations based on geometric optics and experimentally-determined scattering phase functions for aluminosilicate particles.

14 SOLAR ENERGY↗
DOE OSTI2025

Pseudo-viscous modeling of transport in dense granular flows for thermal energy storage applications

Dense, granular flows were examined to effectively capture and model bulk viscous properties in thin packed beds. A modified Couette cell with particle image velocimetry was used to experimentally determine pseudo-viscosity properties of four particulate media with varying morphologies: (1) iron oxide-coated SiO 2 particles, (2) CARBOBEAD CP30-60 particles, (3) CARBOBEAD CP40-100 particles, and (4) Al 2 O 3 beads. The pseudo-viscosity functions were fitted using a power law to correlate the measured shear stress as a function of measured shear rate. The pseudo-viscous functions were used as inputs to computation fluid dynamics models for a single-phase viscous fluid to predict granular flow profiles. Steady-state free surface velocity profiles at angular velocities <7 rad/s predicted by the model were in good agreement with the experimental particle image velocimetry measurements, resulting in Pearson correlation coefficients of 0.97 for iron-oxide coated SiO 2 particles and 0.95 for CP30-60 particles. As a result, this alternative approach to measuring pseudo-viscous properties under shearing and modeling bulk transport behavior of granular flow using computation fluid dynamics model offered significant reduction in computational load compared to discrete element methods.

14 SOLAR ENERGY↗
DOE OSTI2020

Strength of porous α-SiO 2 in a shock loaded environment: Calibration via Richtmyer–Meshkov instability and validation via Mach lens

The strength of brittle porous media is of concern in numerous applications, for example, earth penetration, crater formation, and blast loading. Thus, it is of importance to possess techniques that allow for constitutive model calibration within the laboratory setting. The goal of the current work is to demonstrate an experimental technique allowing for strength assessment of porous media subjected to shock loading, which can be implemented into pressure-dependent yield surfaces within numerical simulation schemes. As a case study, the deviatoric response of distended α-SiO 2 has been captured in a tamped Richtmyer–Meshkov instability (RMI) environment at a pressure regime of 4–10 GPa. Hydrocode simulations were used to interpret RMI experimental data, and a resulting pressure-dependent yield surface akin to the often employed modified Drucker–Prager model was calibrated. Simulations indicate that the resulting jet length generated by the RMI is sensitive to the porous media strength, thereby providing a feasible experimental platform capable of capturing the pressurized granular deviatoric response. Furthermore, in efforts to validate the RMI-calibrated strength model, a set of Mach-lens experiments was performed and simulated with the calibrated pressure-dependent yield surface. Excellent agreement between the resulting Mach-lens length in experiment and simulation provides additional confidence to the RMI yield-surface calibration scheme.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Economic, Greenhouse Gas, and Resource Assessment for Fuel and Protein Production from Microalgae: 2022 Algae Harmonization Update

This report presents an updated "harmonization study" documenting the collaborative analysis of microalgae cultivation and conversion to fuels and products. Four national laboratory modeling teams reconvened to investigate the resource, economic, and environmental sustainability implications of integrated systems encompassing large-scale algae farms and conversion biorefineries. Relative to prior harmonization analyses conducted by these partners, the present effort focuses on more near-term deployment potential based on the use of nutrient-replete, high-protein algal biomass compositions (more readily achievable today without sacrificing cultivation productivity), though this also incurs challenges in lower fuel yields and accordingly higher costs and carbon intensities for the overall integrated systems. Additionally, the present assessment adds further granularity around carbon dioxide (CO 2 ) sourcing and transport via carbon capture of nearby point sources, as well as handling of high-saline cultivation media and resultant blowdown/disposal processing. Finally, this assessment focuses on conversion opportunities to produce both fuel (prioritizing sustainable aviation fuel, in this case via hydrothermal liquefaction) and protein products for the food and feed markets, recognizing growing needs for such products.

09 BIOMASS FUELS↗
DOE OSTI2024

Economic, Greenhouse Gas, and Resource Assessment for Fuel and Protein Production from Microalgae: 2022 Algae Harmonization Update

This report presents an updated “harmonization study” documenting the collaborative analysis of saline microalgae cultivation and conversion to fuels and products. Four national laboratory modeling teams reconvened to investigate the resource, economic, and environmental sustainability implications of integrated systems encompassing large-scale algae farms and conversion biorefineries. Relative to prior harmonization analyses conducted by these partners, the present effort focuses on more near-term technology potential based on the use of nutrient-replete, high-protein algal biomass compositions (more readily achievable today without sacrificing cultivation productivity) coupled with individual algae farms varying in size but generally smaller at 3,900 acres on average (more realistic in practice than a fixed 5,000-acre farm scale previously considered). Additionally, the present assessment adds further granularity around carbon dioxide (CO 2 ) sourcing and transport via carbon capture of nearby point sources, as well as handling of high-saline cultivation media and resultant blowdown/disposal processing. Finally, this assessment focuses on conversion opportunities to produce both fuel (prioritizing sustainable aviation fuel [SAF], in this case via hydrothermal liquefaction) and protein products for the food and feed markets, recognizing growing needs for such products.

09 BIOMASS FUELS↗
NASA NTRSDate not supplied

PFAS Treatment Pilot Study using Granular Activated Carbon at Kennedy Space Center, Florida

Per- and polyfluoroalkyl substances (PFAS) have been found in investigative derived waste (IDW) generated from groundwater sampling and remediation activities conducted at Kennedy Space Center (KSC), Florida. PFAS are exceptionally strong compounds because of carbon-fluorine bonds resulting in resistance to degradation, low chemical reactivity, compound stability, and persistence in the environment. The regulatory status of PFAS is very dynamic. PFAS is not considered a hazardous waste and has no federal or state (Florida) cleanup requirements at this time. Due to the current and unknown future of the regulatory and treatment landscape, non-hazardous IDW, based upon site volatile organic compounds (VOCs) regulated under Title 40 of Federal Regulations part 261, containing PFAS is not being processed for off-site waste disposal under KSC’s Resource Conservation and Recovery Act permit as a proactive precaution. Long-term storage of aqueous IDW in the meantime was determined to be inadequate due to the potential for spills and/or leaks. A very limited number treatment methods are available at this time. To date, granular activated carbon (GAC) and ion exchange technologies have been found to be some of the most consistent treatment options for removing PFAS from aqueous media. Therefore, a pilot study using GAC was developed at KSC to determine the feasibility of treating non-hazardous IDW containing PFAS to reduce the total volume of PFAS waste and minimize the risk of leaks or spills while storing the waste until complete PFAS-destructive treatment options are more readily available. NASA wanted the pilot test to be able to demonstrate the ability to completely remove 18 PFAS compounds and the site VOCs to below the state of Florida groundwater cleanup target levels (GCTLs).

Michael J Deliz↗
NASA NTRS1999

Evidence for Methane Segregation at the Surface of Pluto

In May 1995, a set of spectrophotometric curves of the system Pluto-Charon was recorded with the UKIRT telescope equipped with the spectrometer CGS4. As for the previous observations, the spectra cover a part of the near infrared range, between 1.4 and 2.55 micrometers, but with a higher resolution of approximately 700. In both the 1992 and 1995 data, the existence of solid methane is confirmed by numerous absorption bands, and the carbon monoxide and the nitrogen ices are identified by their respective signatures at 2.35 and 2.15 um. The solid nitrogen seems to be the principal icy component and forms a matrix in which the CH4 and CO molecules are diluted. However a spectroscopic analysis of the 1995 observations indicates that pure methane may coexist with its diluted phase in N2. In order to derive the horizontal and vertical distribution of these different species and to obtain some quantitative information about their characteristics, we have modeled the spectrum of May 15 that corresponds to the maximum of Pluto's visible light curve. This was achieved by means of a radiative transfer algorithm dealing with compact and stratified media. Among the various representations we have tested to describe the surface of Pluto, only a geographical mixture of three distinct units explains all the significant structures of the analyzed spectrum. The first unit is a thin granular layer of pure CH4 covering a compact polycrystalline substratum of N2-CH4-CO, which are in a molecular mixture (concentrations of and CO of the order of 0.45%, 0.1-0.2% respectively). It covers about 70% of the observed area and corresponds to volatile deposits that are sublimating under solar illumination. The second unit is either (a) a single thick layer of pure granular methane or (b) a unit similar to the first unit but with the two components inverted (i.e. with CH4 forming a substratum and the N2-CH4-CO mixture a superficial layer of fine grains). Covering 20% of the surface, it represents some old surfaces that have been sublimated for a long time, and eventually recovered later by very small amounts of fresh deposits of the molecular mixture N2-CH4-CO. Finally, the third unit may result from the condensation of very fine grains of nearly pure N2. It covers the remainder of the surface (about 10%). All these results allow a better understanding of the processes of deposition, metamorphism, sublimation and transport affecting the different ices detected on Pluto during its climatic cycles.

Doute, S.↗
DOE OSTI2022

Advanced Characterization of Particulate Flows for Concentrating Solar Power Applications

The overarching goal of this project was to gain a greater fundamental understanding of heat and mass transfer in particulate-media in concentrated solar power (CSP) applications for thermal energy storage (TES) and to disseminate results to support parallel Gen3 research initiatives. Project objectives were achieved through three planned project phases to systematically characterize the heat transfer and flow properties for particulate (granular) flows at elevated temperatures up to 800 °C. These objectives were accomplished using a combination of fundamental experimental measurements, modeling, and simplified flow experiments over a range of temperatures. This work addressed a serious gap within the field related to the understanding and modeling of granular flow behavior and the related heat transfer at different temperatures, which directly correspond to the operating points of CSP applications which use particles for heat storage.

14 SOLAR ENERGY↗
DOE OSTI2021

Electrical conductivity of porous binary powder mixtures

Simultaneous data of the quasi-static compaction and electrical conductivity of porous, binary powder mixtures have been collected as a function of bulk density. The powder mixtures consist of a metal conductor, either titanium or iron, an insulator, and pores filled with ambient air. The data show a dependency of the conductivity in terms of relative bulk density and metal volume fraction on conductor type and conductor particle characteristics of size and shape. Finally, finite element models using particle domains generated by discrete element method are used to simulate the bulk conductivity near its threshold while the general effective media equation is used to model the conductivity across the compression regime.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

A Forward Feedback Control Scheme for a Solar Thermochemical Moving Bed Counter-Current Flow Reactor

Abstract Pelletized thermochemical energy storage media has a potential for long-duration energy storage. Production of solid-state energy storage media can be done within a cavity chemical reactor that captures concentrated solar radiation from a solar thermal field. The temperature stability of a solar reactor is directly influenced by the solar flux intercepted. This paper presents a low-order physical model to simulate the dynamic response of temperature inside a tubular plug-flow reactor prototype. Solid granular particles are fed to the reactor from the top whereas a counter-current flowing gas enters the reactor from the bottom. An in-house code was developed to model transient heat transfer of the reactor wall, gas, and moving particles. The model was preliminarily validated with packed beds for different temperature ranges and two gas flowrates. Dynamic response of the reactor temperature is simulated for different input power and gas/particle flowrates. The results show that the system response can be controlled efficiently by utilizing input power (solar flux) as a control parameter. A conventional proportional integral (PI) controller is designed to control the temperature inside the reactor and to maintain it during the solar flux intermittency. The controller parameters are tuned using the Ziegler–Nichols method to ensure optimal system response. The results show that the feedback control model is successful in tracking different reference reactor temperatures within a reasonable settling time of 30 min and eliminated overshoot. This study can be extended to include a hybrid reactor with a multi-input, multi-output variable system.

Energy & Fuels↗
NASA NTRS2010

DEM Solutions Develops Answers to Modeling Lunar Dust and Regolith

With the proposed return to the Moon, scientists like NASA-KSC's Dr. Calle are concerned for a number of reasons. We will be staying longer on the planet's surface, future missions may include dust-raising activities, such as excavation and handling of lunar soil and rock, and we will be sending robotic instruments to do much of the work for us. Understanding more about the chemical and physical properties of lunar dust, how dust particles interact with each other and with equipment surfaces and the role of static electricity build-up on dust particles in the low-humidity lunar environment is imperative to the development of technologies for removing and preventing dust accumulation, and successfully handling lunar regolith. Dr. Calle is currently working on the problems of the electrostatic phenomena of granular and bulk materials as they apply to planetary surfaces, particularly to those of Mars and the Moon, and is heavily involved in developing instrumentation for future planetary missions. With this end in view, the NASA Kennedy Space Center's Innovative Partnerships Program Office partnered with OEM Solutions, Inc. OEM Solutions is a global leader in particle dynamics simulation software, providing custom solutions for use in tackling tough design and process problems related to bulk solids handling. Customers in industries such as pharmaceutical, chemical, mineral, and materials processing as well as oil and gas production, agricultural and construction, and geo-technical engineering use OEM Solutions' EDEM(TradeMark) software to improve the design and operation of their equipment while reducing development costs, time-to-market and operational risk. EDEM is the world's first general-purpose computer-aided engineering (CAE) tool to use state-of-the-art discrete element modeling technology for the simulation and analysis of particle handling and manufacturing operations. With EDEM you'can quickly and easily create a parameterized model of your granular solids system. Computer-aided design (CAD) models of real particles can be imported to obtain an accurate representation of their shape. EDEM(TradeMark) uses particle-scale behavior models to simulate bulk solids behavior. In addition to particle size and shape, the models can account for physical properties of particles along with interaction between particles and with equipment surfaces and surrounding media, as needed to define the physics of a particular process.

Dunn, Carol Anne↗
NASA NTRS2007

Ejecta- and Size-Scaling Considerations from Impacts of Glass Projectiles into Sand

One of the most promising means of learning how initial impact conditions are related to the processes leading to the formation of a planetary-scale crater is through scaling relationships.1,2,3 The first phase of deriving such relationships has led to great insight into the cratering process and has yielded predictive capabilities that are mathematically rigorous and internally consistent. Such derivations typically have treated targets as continuous media; in many, cases, however, planetary materials represent irregular and discontinuous targets, the effects of which on the scaling relationships are still poorly understood.4,5 We continue to examine the effects of varying impact conditions on the excavation and final dimensions of craters formed in sand. Along with the more commonly treated variables such as impact speed, projectile size and material, and impact angle,6 such experiments also permit the study of changing granularity and friction angle of the target materials. This contribution presents some of the data collected during and after the impact of glass spheres into a medium-grained sand.

Anderson J. L. B.↗
NASA NTRS1991

Three-dimensional cultured glioma cell lines

Three-dimensional glioma spheroids were produced in vitro with size and histological differentiation previously unattained. The spheroids were grown in liquid media suspension in a Johnson Space Center (JSC) Rotating Wall Bioreactor without using support matrices such as microcarrier beads. Spheroid volumes of greater than 3.5 cu mm and diameters of 2.5 mm were achieved with a viable external layer or rim of proliferating cells, a transitional layer beneath the external layer with histological differentiation, and a degenerative central region with a hypoxic necrotic core. Cell debris was evident in the degenerative central region. The necrotics centers of some of the spheroids had hyaline droplets. Granular bodies were detected predominantly in the necrotic center.

Gonda, Steve R.↗
DOE OSTI2021

A Geometry-Driven Longitudal Topic Model

A simple and scalable framework for longitudinal analysis of Twitter data is developed that combines latent topic models with computational geometric methods. Dimensionality reduction tools from computational geometry are applied to learn the intrinsic manifold on which the latent, temporal topics reside. Then shortest path distances on the manifold are used to link together these topics. The proposed framework permits visualization of the low-dimensional embedding which provides clear interpretation of the complex, high-dimensional trajectories that may exist among latent topics. Practical application of the proposed framework is demonstrated through its ability to capture and effectively visualize natural progression of latent COVID-19 related topics learned from Twitter data. Interpretability of the trajectories is achieved by comparing to real-world events. In addition, the framework permits study of spatial variation in Twitter behavior for learned topics. The analysis demonstrates that the proposed framework is able to capture granular-level impact of COVID-19 on public discussions. We end by arguing that Twitter data, when analyzed within the proposed framework, can serve as a valuable supplementary data stream for COVID-related studies.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1994

Modeling thermal infrared (2-14 micrometer) reflectance spectra of frost and snow

Existing theories of radiative transfer in close-packed media assume that each particle scatters independently of its neighbors. For opaque particles, such as are common in the thermal infrared, this assumption is not valid, and these radiative transfer theories will not be accurate. A new method is proposed, called 'diffraction subtraction', which modifies the scattering cross section of close-packed large, opaque spheres to account for the effect of close packing on the diffraction cross section of a scattering particle. This method predicts the thermal infrared reflectance of coarse (greater than 50 micrometers radius), disaggregated granular snow. However, such coarse snow is typically old and metamorphosed, with adjacent grains welded together. The reflectance of such a welded block can be described as partly Fresnel in nature and cannot be predicted using Mie inputs to radiative transfer theory. Owing to the high absorption coefficient of ice in the thermal infrared, a rough surface reflectance model can be used to calculate reflectance from such a block. For very small (less than 50 micrometers), disaggregated particles, it is incorrect in principle to treat diffraction independently of reflection and refraction, and the theory fails. However, for particles larger than 50 micrometers, independent scattering is a valid assumption, and standard radiative transfer theory works.

Wald, Andrew E.↗
DOE OSTI2020

Removal of radionuclides from acidic solution by activated carbon impregnated with methyl- and carboxy-benzotriazoles

The removal efficiencies of metals commonly used to model the fate and transport of aqueous uranium and radioactive its daughter products, were observed on activated carbons impregnated with different benzotriazole derivatives. Acidic solutions containing U(VI), Sr(II), Eu(III), and Ce(III) were used to determine the immobilization potential of carboxybenzotriazole (CBT) and methylbenzotriazole (MeBT), where these derivatives were sorbed to different types of granular activated carbon (GAC). This sorption behavior can be predicted by Redlich–Peterson model. Flow-through column tests showed that the immobilization of uranium and some of its daughter products, significantly improves in response to oxidized GACs saturated with carboxybenzotrzole (CBT), which reached a maximum elimination for U(VI) at 260 BV, Eu(III) at 114 BV, Ce(III) at 126 BV, and Sr(II) at 100. MeBT significantly desorbed from GAC under acidic conditions. Trace amounts of CBT were observed in some column effluents, but this did not appear to alter the effectiveness of metal removal, regardless of the model radionuclide studied. These results suggest that enhanced immobilization of selected metals on GAC, can be achieved by impregnating oxidized activated carbon with carboxylated benzotriazoles, and that metal removal efficiency on this media, is related to their valence and ionic radius in acidic environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗