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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1956

Performance of Pentaborane, Pentaborane - JP-4 Fuel Mixtures, and Trimethylborate Azeotrope Fuel in a Full-scale Turbojet Engine

This report summarizes the full-scale engine tests of pentaborane, pentaborane - JP-4 fuel mixtures, and trimethylborate azeotrope fuel. The tests were conducted in a full-scale turbojet engine at a simulated altitude of 50,000 feet and Mach number of 0.08. Engine speeds were 90 to 100 percent of rated speed. Pentaborane reduced the the specific fuel consumption to two-thirds that of JP-4 fuel. However, because boron oxide collected in the engine, the performance deteriorated with continued operation of pentaborane in each of the short-duration tests reported.

Breitwiesser, Roland↗
NASA NTRS1933

Experiments on the Distribution of Fuel in Fuel Sprays

The distribution of fuel in sprays for compression-ignition engines was investigated by taking high-speed spark photographs of fuel sprays reproduced under a wide variety of conditions, and also by injecting them against pieces of plasticine. A photographic study was made of sprays injected into evacuated chambers, into the atmosphere, into compressed air, and into transparent liquids. Pairs of identical sprays were injected counter to each other and their behavior analyzed. Small high velocity air jets were directed normally to the axes of fuel sprays, with the result that the envelope of spray which usually obscures the core was blown aside, leaving the core exposed on one side. The results showed that the distribution of the fuel within the sprays was very uneven.

Lee, Dana W↗
NASA NTRS1995

Dimethoxymethane: A Fuel For Direct-Oxidation Fuel Cells

Dimethoxymethane (DMM) identified as one of several high-energy fuels for direct-oxidation fuel cells. Found to undergo facile electro-oxidation to carbon dioxide and water, with methanol as possible intermediate product. Fuel electro-oxidized at sustained high rates without poisoning electrodes. Performance superior to that of methanol at same temperature. Synthesized from natural gas (methane) and is thus viable alternative to methanol in direct-oxidation fuel cells. Better performance expected at higher temperature and by use of Pt/Sn catalyst. Alternatively, low boiling temperature of DMM also makes it candidate for gas-feed operation.

Olah, George A.↗
NASA NTRS1995

Trioxane: A Fuel For Direct-Oxidation Fuel Cells

Trioxane identified as high-energy, nontoxic, solid substitute for formaldehyde as water-soluble fuel for use in direct-oxidation fuel cells. Found to undergo facile electrochemical oxidation to water and carbon dioxide at platinum and platinum-alloy electrodes in liquid-feed-type fuel cells that contain acid electrolytes or solid proton-exchange membrane electrolytes. Exhibits less crossover than do such conventional fuels as methanol and formaldehyde. Being solid at ambient temperature, trioxane offers significant advantages in handling and transportation. Synthesized from natural gas with relative ease.

Olah, George A.↗
NASA NTRS1999

Effects of Passive Fuel-Air Mixing Control on Burner Emissions Via Lobed Fuel Injectors

The present experimental study examines the effects of differing levels of passive fuel-air premixing on flame structures and their associated NO(x) and CO emissions. Four alternative fuel injector geometries were explored, three of which have lobed shapes. These lobed injectors mix fuel and air and strain species inter-faces to differing extents due to streamwise vorticity generation, thus creating different local or core equivalence ratios within flow regions upstream of flame ignition and stabilization. Prior experimental studies of two of these lobed injector flowfields focused on non-reactive mixing characteristics and emissions measurements for the case where air speeds were matched above and below the fuel injector, effectively generating stronger streamwise vorticity than spanwise vorticity. The present studies examine the effects of airstream mismatch (and hence additional spanwise vorticity generation), effects of confinement of the crossflow to reduce the local equivalence ratio, and the effects of altering the geometry and position of the flameholders. NO(x) and CO emissions as well as planar laser-induced fluorescence imaging (PLIF) of seeded acetone are used to characterize injector performance and reactive flow evolution.

Mitchell, M. G.↗
NASA NTRS2018

Flame Tube Testing of a GEA TAPS Injector: Effects of Fuel Staging on Combustor Fuel Spray Patterns, Flow Structure, and Speciation

This paper presents results in which we compare fuel staging and its effect on fuel spray pattern, velocity and speciation during combustion for several inlet conditions using a GE TAPS injector configuration. Planar laser-induced fluorescence (PLIF), particle image velocimetry (PIV) and phase Doppler interferometry (PDI) were used to investigate spray patterns and velocity. The 2D PIV provides slices in the flow of axial-vertical or axial horizontal velocity components. With 3D PDI, we obtained 3 components of velocity, and fuel drop sizes. Chemiluminescence imaging and spontaneous Raman scattering (SRS) were used to investigate flame structure, species location and relative species concentration. Phase Doppler and PIV data were acquired using scatter from fuel droplets; therefore, those data were obtained only at the pilot-only test points. Raman measurements were acquired only at 10/90 split points to avoid droplets.

GE TAPS↗
NASA NTRS2020

Simulation of Hydrogen Flow in a Nuclear-Thermal Propulsion Reactor Subsystem: Conjugate Heat Transfer in Surrogate Fuel Elements and Flow Through the Dome Inlet to the Fuel Elements

NASA is performing research related to a Nuclear-Thermal Propulsion (NTP) engine as a step toward future manned missions to Mars. BWX Technologies (BWXT), in conjunction with NASA, is developing the reactor subsystem for that NTP engine design. As a subset of the reactor subsystem, the fuel elements have continued to evolve in design, as well. A set of experiments within the Nuclear Thermal Reactor Element Environmental Simulator at NASA Marshall has been developed to compliment that design process, including a series of surrogate fuel elements. Before the experiments of each surrogate can be completed, they must be deemed safe using structural analysis, which itself requires thermal and conjugate heat transfer analyses of the articles. Therefore, conjugate heat transfer simulations of the hydrogen flow through the test article fuel element surrogates were developed to provide estimates of heating, as well as to provide assessments of the fluid flow through the elements. The set of simulations involved not only the separate test conditions, but also a sensitivity study to estimate the effect of physical parameter uncertainty on the selected quantities of interest. Additionally, the fluid flow through the fore section inner plenum dome to the entrances of the fuel elements, another section of the reactor subsystem still under active development, was simulated and analyzed. The simulations show the extent of non-uniformity in the mass flow distribution across the dome outlets. Furthermore, additional analyses estimate the effects of required flow blockages on the potential development of flow dynamics. These analyses were used in the design cycle to make improvements to the reactor subsystem design.

Kalen E. Braman↗
DOE OSTI2019

Fuel injector for high flame speed fuel combustion

A multiple fuel capable, pre-mixed, low emission injector is provided which is particularly suited for burning high flame speed fuels. The fuel injector includes an injector body having a preliminary pre-mixing chamber, an intermediate pre-mixing chamber and a final pre-mixing chamber. A fuel distributor separates the preliminary pre-mixing chamber from the intermediate pre-mixing chamber. A guide vane separates the intermediate pre-mixing chamber from the final pre-mixing chamber.

Chen, Junhua↗
DOE OSTI2014

Pyrolysis fuels and methods for processing pyrolysis fuels

Pyrolysis fuels and methods for processing pyrolysis fuel are provided. In one embodiment, a method of processing pyrolysis fuel converts biomass to pyrolysis fuel including pyrolysis oil and char particles. Also, the method includes resizing a portion of the char particles so that substantially all resized char particles have a largest dimension no greater than about 5 microns.

Baird, Lance Awender↗
DOE OSTI2019

Effect of Fuel Reactivity and End- Gas Temperature on Autoignition and Flame Propagation Rate in Primary Reference Fuel Mixtures at Elevated Temperature and Pressure

Knock in spark-ignited (SI) engines is initiated by autoignition in the unburned gases upstream of spark-ignited, propagating, turbulent premixed flames. In this study, knock propensity of SI fuels was quantified via observations of end-gas autoignition (EGAI) in unburned gases upstream of laser-ignited, premixed flames at elevated pressures and temperatures in a rapid compression machine. Stoichiometric primary reference fuel (n-heptane/isooctane) blends of varying reactivity were ignited using an Nd:YAG laser over a range of compressed temperatures and pressures, all in excess of 691 K and 18.8 bar. High-speed pressure measurements and schlieren images indicated the presence of EGAI in the unburned gases upstream of spherical, outwardly propagating flames. The fraction of the total heat release attributed to EGAI was found to vary with fuel reactivity and the time-integrated temperature of the end-gas prior to ignition. Flame propagation rates, measured using schlieren imaging, did not vary strongly with fuel reactivity but were affected by turbulence caused by variation in piston timing. Under conditions of low turbulence, measured flame propagation rates agreed with one-dimensional premixed laminar flame speed computations performed at the same conditions.

Zdanowicz, Andrew↗
DOE OSTI2019

Effect of Fuel Reactivity and End-Gas Temperature on Autoignition and Flame Propagation Rate in Primary Reference Fuel Mixtures at Elevated Temperature and Pressure

Knock in spark-ignited (SI) engines is initiated by autoignition in the unburned gases upstream of spark-ignited, propagating, turbulent premixed flames. In this study, knock propensity of SI fuels was quantified via observations of end-gas autoignition (EGAI) in unburned gases upstream of laser-ignited, premixed flames at elevated pressures and temperatures in a rapid compression machine. Stoichiometric primary reference fuel (n-heptane/isooctane) blends of varying reactivity were ignited using an Nd:YAG laser over a range of compressed temperatures and pressures, all in excess of 691 K and 18.8 bar. High-speed pressure measurements and schlieren images indicated the presence of EGAI in the unburned gases upstream of spherical, outwardly propagating flames. The fraction of the total heat release attributed to EGAI was found to vary with fuel reactivity and the time-integrated temperature of the end-gas prior to ignition. Flame propagation rates, measured using schlieren imaging, did not vary strongly with fuel reactivity but were affected by turbulence caused by variation in piston timing. Under conditions of low turbulence, measured flame propagation rates agreed with one-dimensional premixed laminar flame speed computations performed at the same conditions.

End-Gas Autoignition, Engine Knock, Rapid Compress↗
DOE OSTI2023

Nuclear fuel elements including protective structures, and related method of forming a nuclear fuel element

A nuclear fuel element includes a core comprising a fissile element and an additional element. A protective structure surrounds the core and comprises at least a first material surrounding the nuclear fuel. The first material comprises the fissile element and the additional element and comprises a greater than stoichiometric amount of the additional element. An outer portion of the nuclear fuel element comprises a metal. Related nuclear fuel elements, and related methods are also disclosed.

Griffith, George W.↗
DOE OSTI2024

Gaseous fuel engine system and operating strategy for limiting crankcase fuel accumulation

Operating a gaseous fuel engine system includes controlling at least one of a delivery location, a delivery timing, or in situ mixing of a gaseous fuel with air, based on at least one engine system parameter upon the basis of which a blowby amount of a gaseous fuel to a crankcase varies. Crankcase accumulation of the gaseous fuel is maintained below a flammability limit. Related apparatus and control logic is also disclosed.

Singh, Jaswinder↗
DOE OSTI2021

Recent Advances in Electrocatalysts for Proton Exchange Membrane Fuel Cells and Alkaline Membrane Fuel Cells

The rapid progress of proton exchange membrane fuel cells (PEMFCs) and alkaline exchange membrane fuel cells (AMFCs) has boosted the hydrogen economy concept via diverse energy applications in the past decades. For a holistic understanding of the development status of PEMFCs and AMFCs, recent advancements in electrocatalyst design and catalyst layer optimization, along with cell performance in terms of activity and durability in PEMFCs and AMFCs, are summarized in this report. The activity, stability, and fuel cell performance of different types of electrocatalysts for both oxygen reduction reaction and hydrogen oxidation reaction are discussed and compared. Research directions on the further development of active, stable, and low-cost electrocatalysts to meet the ultimate commercialization of PEMFCs and AMFCs are also discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2014

First elevated-temperature performance testing of coated particle fuel compacts from the AGR-1 irradiation experiment

In the AGR-1 irradiation experiment, 72 coated-particle fuel compacts were taken to a peak burnup of 19.5% fissions per initial metal atom with no in-pile failures. This paper discusses the first post-irradiation test of these mixed uranium oxide/uranium carbide fuel compacts at elevated temperature to examine the fuel performance under a simulated depressurized conduction cooldown event. A compact was heated for 400 h at 1600 degrees C. Release of 85Kr was monitored throughout the furnace test as an indicator of coating failure, while other fission product releases from the compact were periodically measured by capturing them on exchangeable, water-cooled deposition cups. No coating failure was detected during the furnace test, and this result was verified by subsequent electrolytic deconsolidation and acid leaching of the compact, which showed that all SiC layers were still intact. However, the deposition cups recovered significant quantities of silver, europium, and strontium. Based on comparison of calculated compact inventories at the end of irradiation versus analysis of these fission products released to the deposition cups and furnace internals, the minimum estimated fractional losses from the compact during the furnace test were 1.9 x 10-2 for silver, 1.4 x 10-3 for europium, and 1.1 x 10-5 for strontium. Other post-irradiation examination of AGR-1 compacts indicates that similar fractions of europium and silver may have already been released by the intact coated particles during irradiation, and it is therefore likely that the detected fission products released from the compact in this 1600 degrees C furnace test were from residual fission products in the matrix. Gamma analysis of coated particles deconsolidated from the compact after the heating test revealed that silver content within each particle varied considerably; a result that is probably not related to the furnace test, because it has also been observed in other as-irradiated AGR-1 compacts. X-ray imaging of selected particles was performed to examine the internal microstructure. This examination revealed variable irradiation performance of the coating layers, but sufficient statistical sampling is not yet available to identify any possible correlation to variation in individual particle fission product retention.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2022

Techno-economic Analysis and Life-Cycle Analysis of Renewable Diesel Fuels Produced with Waste Feedstocks

Wet waste feedstocks represent an important category of resources that could be utilized to produce biofuels. Diversion of the wet waste resources from going through conventional waste management practices to utilization as feedstocks for energy production also benefits from avoided cost and pollutant emissions of waste management and disposal. This study investigates the economic and environmental implications of producing bio-blendstocks for mixing controlled compression ignition (MCCI) engines from two waste-to-fuel pathways: hydroprocessed esters and fatty acids (HEFA) from yellow grease, and swine manure hydrothermal liquefaction (HTL) followed by biocrude upgrading. Detailed process models were developed for both pathways, which informed the techno-economic analysis (TEA) and life-cycle analysis (LCA). Conventional swine manure management practice was also modeled in detail as the business-as-usual (BAU) scenario for the swine manure HTL pathway. The estimated minimum fuel selling prices (MFSP) were $4.47/gasoline gallon equivalent (GGE) and $3.57/GGE for the yellow grease to HEFA and swine manure HTL pathways, respectively. The life-cycle greenhouse gas (GHG) emissions of the two pathways were 11.2 and -33.3 g CO2e/MJ, respectively, for the yellow grease to HEFA and swine manure HTL pathways. The credits of avoided emissions from conventional swine manure management were the main reason for the negative GHG emissions of the swine manure HTL pathway. The marginal GHG emissions abatement costs were estimated to be $100 – $253/tonne CO2e and $5 – $103/tonne CO2e for the yellow grease HEFA and swine manure HTL pathways, respectively, for a diesel price ranging between $2.0/GGE and $3.5/GGE. Since the yellow grease HEFA pathway is already commercialized, it can benefit from the $200/tonne carbon credit in the California Low Carbon Fuel Standard (LCFS) market, which could help the yellow grease HEFA pathway to achieve near-zero marginal GHG emissions abatement cost.

renewable diesel, techno economic analysis, life c↗
DOE OSTI2021

Correlating Nanoscale Secondary Ion Mass Spectrometry and Atom Probe Tomography Analysis of Uranium Enrichment in Metallic Nuclear Fuel

Distribution and enrichment of 235U within nuclear fuels are essential to material performance and reactor safety. With the development of metallic U fuels, understanding 235U homogeneity has become increasingly important, however, it is difficult to map with high spatial, and mass resolution to analyze both matrix and secondary phase precipitates. Here, we analyze 235U enrichment in matrix and carbide phases in LEU-Mo via two chemical imaging modalities: nanoscale secondary ion mass spectrometry (nanoSIMS) and atom probe tomography (APT). NanoSIMS and APT provided consistent results, with no statistically significant difference between measured and nominal enrichment (19.75 % 235U).

U-10Mo, atom probe tomography, nanoscale secondary↗