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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Thermal radiation analysis of a pressurized oxy-coal combustor with discrete ordinate model

Concerns over climate change have led to numerous efforts in developing low-carbon energy technologies. Pressurized oxy-combustion (POC) is a promising candidate to reduce carbon emissions in power generation. Pressure strongly impacts thermal radiation, leading to a substantial difference in heat transfer between POC and conventional atmospheric pressure combustion. A good understanding of thermal radiation in POC is needed to aid new combustor development. The present work is a step in this direction, initiating a systematic analysis of thermal radiation and heat transfer in a pilot-scale POC combustor, which has been developed at Washington University in St. Louis (WUSTL). In a POC process, pulverized coal is burned under elevated pressure and O2-CO2 environment. Few researchers have investigated the thermal radiation of pressurized oxy-combustion. This work adopted the discrete ordinate model to simulate the radiation of a 1-D cylinder with predetermined conditions (temperature, pressure, gas compositions) to predict the influence of radiative properties of flue gas on the radiation in the combustor.

Li, Lei↗
NASA NTRS1974

Advanced Rankine and Brayton cycle power systems: Materials needs and opportunities

Conceptual advanced potassium Rankine and closed Brayton power conversion cycles offer the potential for improved efficiency over steam systems through higher operating temperatures. However, for utility service of at least 100,000 hours, materials technology advances will be needed for such high temperature systems. Improved alloys and surface protection must be developed and demonstrated to resist coal combustion gases as well as potassium corrosion or helium surface degradation at high temperatures. Extensions in fabrication technology are necessary to produce large components of high temperature alloys. Long time property data must be obtained under environments of interest to assure high component reliability.

Grisaffe, S. J.↗
NASA NTRS2000

Soot Reaction Properties (Ground-Based Study)

Three major soot reaction processes are needed to predict soot properties in flame environments: soot growth, or the formation of soot on soot nuclei and soot particles; soot oxidation, or the reaction of soot with oxidizing species to yield the combustion products of soot oxidation; and soot nucleation, or the formation of soot nuclei from soot precursors having large molecular weights (generally thought to be large and particularly stable PAH molecules in flame environments, called stabilomers). These processes are addressed in the following, considering soot growth, oxidation and nucleation, in turn, by exploiting the soot and flame structure results for premixed and diffusion flames already discussed in Section 2.

Dai, Z.↗
NASA NTRS1984

Insulation Material

Manufactured by Hitco Materials Division of Armco, Inc. a ceramic fiber insulation material known as Refrasil has been used extensively as a heat-absorbing ablative reinforcement for such space systems as rocket motor nozzles, combustion chambers, and re-entry shields. Refrasil fibers are highly porous and do not melt or vaporize until fibers exceed 3,100 degrees Fahrenheit. Due to these and other properties, Refrasil has found utility in a number of industrial high temperature applications where glass, asbestos and other materials fail. Hitco used this insulation to assist Richardson Co., Inc. in the manufacturing of hard rubber and plastic molded battery cases.

Source record↗
NASA NTRS2010

A Simplified Model for Detonation Based Pressure-Gain Combustors

A time-dependent model is presented which simulates the essential physics of a detonative or otherwise constant volume, pressure-gain combustor for gas turbine applications. The model utilizes simple, global thermodynamic relations to determine an assumed instantaneous and uniform post-combustion state in one of many envisioned tubes comprising the device. A simple, second order, non-upwinding computational fluid dynamic algorithm is then used to compute the (continuous) flowfield properties during the blowdown and refill stages of the periodic cycle which each tube undergoes. The exhausted flow is averaged to provide mixed total pressure and enthalpy which may be used as a cycle performance metric for benefits analysis. The simplicity of the model allows for nearly instantaneous results when implemented on a personal computer. The results compare favorably with higher resolution numerical codes which are more difficult to configure, and more time consuming to operate.

Paxson, Daniel E.↗
DOE OSTI2020

Incineration system and process

An incineration system includes an inlet channel supplying an inlet stream comprising a waste gas containing at least one volatile organic compound, a waste gas sensor measuring at least one property of the waste gas, an oxidizing gas supply controllably providing oxidizing gas to the inlet channel, an incinerator receiving the inlet stream from the inlet channel, an ignitor initiating combustion of the inlet stream in the reaction zone of the incinerator, and a controller receiving data from the waste gas sensor and controlling flow of oxidizing gas from the oxidizing gas supply into the inlet channel. The spiral heat exchanger defines a reaction zone, an incoming path from the inlet channels to the reaction zone, and an outgoing path from the reaction zone to an exhaust channel. The incoming path and the outgoing path extend in alternating concentric spirals with the incoming path being countercurrent to the outgoing path.

42 ENGINEERING↗
DOE OSTI2022

Solution combustion synthesis of iron-based alumina nanocomposites for clean production of hydrogen from fossil fuels

Iron-based alumina nanocomposites are promising materials for microwave-assisted thermocatalytic dehydrogenation of fossil fuels, which has been proposed for the production of hydrogen with no CO2 emissions. Solution combustion synthesis (SCS) is an attractive technique for the fabrication of these materials because it has been used for synthesis of many nanoscale oxides. However, SCS can be carried out using different organic fuels and different heating equipment, and it is important to determine which fuel and heating mode generate materials with the best properties for dehydrogenation, such as maximized specific surface area. In the present work, the iron-based alumina nanocomposites were obtained by SCS using two different fuels (citric acid and glycine) and two different heating modes (a hotplate and a muffle furnace). The precursors/oxidizers were iron nitrate and aluminum nitrate. They were mixed with the fuel according to stoichiometry and dissolved in water. Heating the solution resulted in combustion synthesis. The products were characterized by X-ray diffraction analysis, Brunauer-Emmett-Teller surface area analysis, laser diffraction particle size analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The experiments have shown that the specific surface area of the iron-based alumina nanocomposites obtained by SCS can be dramatically increased by using citric acid instead of glycine, and additionally by using a muffle furnace instead of a hotplate.

Solution combustion synthesis, Nanoscale metal oxi↗
DOE OSTI2016

Oxygen Storage Properties of La 1– x Sr x FeO 3-δ for Chemical-Looping Reactions—An In Situ Neutron and Synchrotron X-ray Study

Oxygen storage materials (OSMs) provide lattice oxygen for a number of chemical-looping reactions including natural gas combustion and methane reforming. La 1–x Sr x FeO 3-δ has shown promise for use as an OSM in methane reforming reactions due to its high product selectivity, fast oxide diffusion, and cycle stability. Here, we investigate the structural evolution of the series La 1–x Sr x FeO 3-δ for x = 0, 1/3, 1/2, 2/3, and 1, using in situ synchrotron X-ray and neutron diffraction, as it is cycled under the conditions of a chemical-looping reactor (methane and oxygen atmospheres). In the compositions x = 1/3, 1/2, 2/3, and 1, we discover an envelope , or temperature range, of oxygen storage capacity (OSC), where oxygen can easily and reversibly be inserted and removed from the OSM. Our in situ X-ray and neutron diffraction results reveal that while samples with higher Sr contents had a higher OSC, those same samples suffered from slower reaction kinetics and some, such as the x = 1/2 and x = 2/3 compositions, had local variations in Sr content, which led to inhomogeneous regions with varying reaction rates. Therefore, we highlight the importance of in situ diffraction studies, and we propose that these measurements are required for the thorough evaluation of future candidate OSMs. Furthermore, we recommend La 2/3 Sr 1/3 FeO 3-δ as the optimal OSM in the series because its structure remains homogeneous throughout the reaction, and its OSC envelope is similar to that of the higher doped materials.

Taylor, Daniel D.↗
NASA NTRS1977

Effect of fuel properties on performance of single aircraft turbojet combustor at simulated idle, cruise, and takeoff conditions

The performance of a single-can JT8D combustor was investigated with a number of fuels exhibiting wide variations in chemical composition and volatility. Performance parameters investigated were combustion efficiency, emissions of CO, unburned hydrocarbons and nitrogen oxides, as well as liner temperatures and smoke. The most pronounced effects of changes in fuel composition were observed at simulated cruise and takeoff conditions where smoke and liner temperatures increased significantly as the hydrogen content of the fuel decreased. At the simulated idle condition, emissions of CO and unburned hydrocarbons increased slightly and, accordingly, combustion efficiencies decreased slightly as the hydrogen content of the fuels decreased.

Butze, H. F.↗
DOE OSTI2022

Analysis of combustion chamber deposit growth on temperature swing thermal barrier coatings in a spark ignition engine

Temperature swing thermal barrier coatings (TBCs) have the potential to improve efficiency and performance through thermal management of the combustion chamber. However, the effects of combustion chamber deposits (CCDs) on the surface of the TBCs are unclear. Therefore, this paper analyzes the impact of CCD formation on a temperature swing TBC. A piston and a heat flux probe coated with a novel material are installed in a single-cylinder research engine at a low-load condition for 62.5 h to promote CCD growth. Every 12.5 h, the performance at a knock limited condition is assessed and thermophysical property measurements on the heat flux probe are performed. Net thermal efficiency increased by 0.4% absolute after 12.5 h relative to the baseline condition, but further CCD growth caused a dithering of efficiency between the 12.5 h and baseline points. The KLSA retarded consistently throughout this period. As a result, external property measurements with the coated heat flux probe showed an improvement in the thermophysical properties of the TBC/CCD layer.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

The influence of synthesis methods on the morpho - structural and luminescent characteristics of rare earth silicate phosphors

Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by two different wet-chemical synthesis routes namely: simultaneous addition of reagents (SimAd) and solution combustion (SC) using yttriumcerium nitrate and urea as starting materials. TEOS or SiO{sub 2} fume were used as Si sources. A comparative study regarding the morpho-structural and luminescent properties of Y{sub 2}SiO{sub 5}:Ce phosphors is presented. The influence of the silicon source, same as the firing temperature on the samples characteristics were discussed. TG-SDTA, FT-IR, SEM, XRD and photoluminescence investigations were used to characterize the precursors and the corresponding phosphors.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Synthesis and characterization of ferrite-semiconductor nano composite for photocatalytic degradation of aqueous nitrobenzene solution

Nanoparticles of semiconductor TiO{sub 2}, zinc ferrite (ZnFe{sub 2}O{sub 4}) and ZnFe{sub 2}O{sub 4}-TiO{sub 2} composite, were synthesized by auto combustion route. Subsequent characterization of synthesized photocatalysts was carried out by X-ray powder diffractometry, transmission electron microscopy, UV-Vis-Diffuse Reflectance Spectroscopy to study the structural and textural properties. The specific surface area, pore diameter and pore volume of synthesized materials were investigated by N{sub 2} adsorption analysis while the presence of TiO{sub 2} in the composite material was verified by infrared spectral analysis. The photocatalytic activity of synthesized photocatalysts was evaluated by degradation of nitrobenzene (NB) in aqueous medium under irradiation of ultraviolet light. The result revealed that 77, 73 and 70% of NB was degraded using TiO{sub 2}, ZnFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4}-TiO{sub 2} photocatalysts after 4h in the presence of UV irradiation. The composite photocatalyst was found easy to separate from the treated solution.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Battery charging goes quantum

Rechargeable lithium-ion batteries power consumer electronics and electric vehicles, making them an essential component of the modern economy. Although lithium-ion battery technology has improved continuously over the past decades, widespread adoption of electrified transportation requires charging in less than 15 min to be competitive with internal combustion engines. As a battery charges and discharges, lithium ions travel across the electrode-electrolyte interface. The rate at which lithium ions transfer is dictated by the structure and physical properties of electrolytes and lithium-storing electrodes. Yet, the exact chemical reaction mechanism underlying the insertion of lithium ions at the electrode-electrolyte interface remains elusive. On page 46 of this issue, Zhang et al. (1) report experimental evidence that shows that lithium-ion battery charge and discharge occur through a coupled ion-electron transfer mechanism. Furthermore, this could establish an experimental and theoretical platform to extract key parameters for optimizing charge transfer rates in lithium-ion batteries.

Warburton, Robert E. [Case Western Reserve Univers↗
DOE OSTI2021

Determination of Water Content in Bio-Oils by Volumetric Karl Fischer Titration: Laboratory Analytical Procedure (LAP)

The water content of bio-oils is a key metric for several reasons. Water is typically the most concentrated single component of fast pyrolysis oils, though this will be much lower in catalytic fast pyrolysis and upgraded products. Reduced water content is preferable in bio-oil as water can contribute to phase separation, corrosivity, and instability. Additionally, lower water is beneficial for physical properties such as energy density. The percentage of water can also be used to correct the calculation for organic oxygen when determining total oxygen content of bio-oils via combustion-based ultimate analysis. The procedure described here is specifically written for the analysis of bio-oils, and is based on ASTM E203, Standard Test Method for Water Using Volumetric Karl Fischer Titration. This standard test method is specified for measuring the mass % water in pyrolysis liquid biofuels in ASTM D7544, Standard Specification for Pyrolysis Liquid Biofuel. Although the standard method is prescribed for the analysis of pyrolysis liquids for use in industrial and commercial burners, the method is not specifically written for this product. The method described with this Laboratory Analytical Procedure (LAP) provides specific guidance for the analysis of bio-oils. Both organic and aqueous phases can be measured with this technique.

09 BIOMASS FUELS↗
NASA NTRS1974

Advanced Rankine and Brayton cycle power systems - Materials needs and opportunities

Conceptual advanced potassium Rankine and closed Brayton power conversion cycles offer the potential for improved efficiency over steam systems through higher operating temperatures. However, for utility service of at least 100,000 hours, materials technology advances will be needed for such high temperature systems. Improved alloys and surface protection must be developed and demonstrated to resist coal combustion gases as well as potassium corrosion or helium surface degradation at high temperatures. Extensions in fabrication technology are necessary to produce large components of high temperature alloys. Long-time property data must be obtained under environments of interest to assure high component reliability.

Grisaffe, S. J.↗
NASA NTRS1979

Theory of deposition of condensible impurities on surfaces immersed in combustion gases

The components resulting from the deposition of inorganic salts (e.g., Na2S04) and oxides present in the combustion products from gas turbine engines were investigated. Emphasis was placed on the effects of multicomponent vapor transport, thermophoretic transport of vapor and small particles to actively cooled surfaces, variable fluid properties within mass transfer boundary layers, and free stream turbulence.

Rosner, D. E.↗
NASA NTRS1984

Study of high performance alloy electroforming

Using the two nickel-manganese alloy electroforming baths of near identical compositions, panels were electroformed under the same deposition parameters of current density, bath temperature, pH, and pulse plating conditions of duty cycle and frequency. By changing the electrolyte agitation conditions, significant effects on mechanical properties were noted. Since electrolyte agitation conditions on the typical flat panels studied to date will not be identical to those existing on a complex curved shape such as the SSME combustion chamber simulation, it is most important that these effects be evaluated prior to Phase B studies. The subscale chamber has been fabricated and shield support tooling is being made. Electroforming of optimized alloy test bars is being deferred until the electrolyte agitation effects are more fully appraised.

Malone, G. A.↗
NASA NTRS1994

Computer program for calculation of complex chemical equilibrium compositions and applications. Part 1: Analysis

This report presents the latest in a number of versions of chemical equilibrium and applications programs developed at the NASA Lewis Research Center over more than 40 years. These programs have changed over the years to include additional features and improved calculation techniques and to take advantage of constantly improving computer capabilities. The minimization-of-free-energy approach to chemical equilibrium calculations has been used in all versions of the program since 1967. The two principal purposes of this report are presented in two parts. The first purpose, which is accomplished here in part 1, is to present in detail a number of topics of general interest in complex equilibrium calculations. These topics include mathematical analyses and techniques for obtaining chemical equilibrium; formulas for obtaining thermodynamic and transport mixture properties and thermodynamic derivatives; criteria for inclusion of condensed phases; calculations at a triple point; inclusion of ionized species; and various applications, such as constant-pressure or constant-volume combustion, rocket performance based on either a finite- or infinite-chamber-area model, shock wave calculations, and Chapman-Jouguet detonations. The second purpose of this report, to facilitate the use of the computer code, is accomplished in part 2, entitled 'Users Manual and Program Description'. Various aspects of the computer code are discussed, and a number of examples are given to illustrate its versatility.

Gordon, Sanford↗