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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

SO2 Plumes Observation with LMOL: Theory, Modeling, and Validation

LMOL, the NASA Langley Mobile Ozone Lidar, is located near NASA’s LaRC steam plant when not deployed in campaigns. The plant produces steam through the incineration of local trash, and its exhaust plume occasionally contains SO2 . SO2 is a known, regulated, pollutant that affects O3 observations in the UV, as is the case with LMOL. In this work, we show how we modified LMOL to detect the plant SO2 plumes and compute its density when the O3 background is stable; we observed densities compatible with what is expected from the typical plume exhaust. The selection of laser lines so that an O3 variation would not get confused with a SO2 detection is explained in details, and a model capable of simulating the Lidar signal with (notably) O3 and SO2 absorption for the validation of the retrieval resolution and uncertainty is presented. Finally, the comparison between the modeled and observed performances of the system is shown: the maximum altitude, resolution, and error in the modeled signal and the observed signals are the same within reasonable margins. This work demonstrates that LMOL is fully capable of working with SO2 . The next step being the addition of an additional laser channel, which is simplified by the tunable aspect of the LMOL laser, to address O3 and SO2 simultaneously, allowing the assessment of SO2 when O3 has variations. Note: This presentation is accompanied by an mp4 video of the given talk.

Guillaume Gronoff↗
NASA NTRSDate not supplied

Observations of So2, O3, and Aerosols With the Langley Mobile Ozone Lidar

LMOL, the NASA Langley Mobile Ozone Lidar, is located near NASA's LaRC steam plant when not deployed in campaigns. The steam plant is an incinerator, and when SO2 was in the plume, it would affect the LMOL O3 measurements at the plume altitudes of 100m-200m. In 2022, we modified LMOL to observe four wavelengths simultaneously to distinguish between and measure both O3 and SO2. With an optimized selection of wavelengths, based on an analysis of the cross-sections, it is possible to retrieve both O3 and SO2 densities from three wavelengths. Adding a fourth wavelength enables better constrains the aerosol's backscatter and extinction. In this work, we present the dual observations of SO2 and O3 with the new channels of LMOL, and we present the advances in constraining the aerosol parameters from these multiple wavelengths. We highlight the SO2 and Ozone Water-Land Environmental Transition Study (SOWLETS) campaign in preparation for the validation of the new system.

Guillaume Gronoff↗
NASA NTRSDate not supplied

Benefits of Trash-to-Gas Versus Jettison of Waste Via Trash-Lock for Mars Transit

Human exploration missions to Mars pose difficulties due to the significant waste that will be generated during transit, which will need to be carried along or disposed of in some fashion. Waste removal from the spacecraft decreases the spacecraft’s mass as well as the associated logistic items necessary for storing the waste. A mission propellant analysis was performed to highlight the mass benefits that may be accessed via waste removal. The propellant mass savings were determined for different waste removal rates (2.9 – 11.6 kg/day) with the highest removal rate leading to the greatest propellant savings of 7,785 kg for an 850-day round-trip mission. Due to these benefits, two methods for waste reduction were studied for the 850-day Mars mission: Trash-to-Gas (TtG) and physical jettison via a trash-lock. The trash-to-gas methods considered were combustion, steam reforming, and pyrolysis, which convert waste into ventable gases (e.g., CO2, CO, CH4, etc.). Combustion and steam reforming require a co-reactant (O2 and/or H2O). Therefore, additional processing units or integration with the spacecraft’s environmental control and life support system (ECLSS) are required to facilitate recycle of the pertinent species. In contrast, pyrolysis is a purely thermal degradation process, which can operate as a standalone system; however, a lower percentage of waste is gasified with pyrolysis. The study herein compares standalone TtG (e.g., Advanced Organic Waste Gasifier, Plasma Pyrolysis, etc.), integrated TtG-ECLSS (e.g., Orbital Syngas Commodity Augmentation Reactor, Incineration/Gasification, etc.), and physical jettison. Each system’s mass, volume, power, and cooling requirements were compared via an equivalent system mass (ESM) analysis to ascertain potentially promising technologies that can achieve efficient waste removal while minimizing their own spacecraft load. This study highlights the advantages and disadvantages of the different waste management technologies and provides recommendations on the promising technologies based on the ESM metric and propellant mass savings.

Jettison↗
NASA NTRSDate not supplied

High-Temperature Slurry Environmental Barrier Coating With Graded HfO 2 -HfSiO 4 Topcoat

Environmental barrier coatings (EBCs) have enabled the use of silicon carbide (SiC)-based ceramic matrix composites (CMCs) in gas turbine engines by protecting the underlying CMC from corrosive combustion species. Current-generation EBCs consist of a rare earth silicate topcoat and a silicon bond coat. The relatively low melting point of the silicon bond coat (1414°C) limits the upper use temperature of these coatings. To protect SiC-based CMCs at temperatures beyond that achievable by the current state-of-the-art, an oxide-based bond coat capable of withstanding temperatures of up to 1482°C has been developed at NASA Glenn Research Center. Hafnia (HfO2) is a promising EBC topcoat material due to its stability in high-temperature steam; however, its coefficient of thermal expansion (CTE) is highly anisotropic and much larger than that of SiC. In this study, a graded HfO2-HfSiO4 topcoat was deposited via a slurry process on the NASA-developed oxide-based bond coat. The oxidation resistance of this EBC system was evaluated at 1482°C in a steam cycling environment. The durability and stability of this slurry-deposited HfO2-HfSiO4 topcoat was compared to that of HfO2 deposited by plasma spray physical vapor deposition (PS-PVD).

EBC↗
NASA NTRSDate not supplied

SiO2 Activity Measurements in the Gd2O3-SiO2 System Via Knudsen Effusion Mass Spectrometry (KEMS)

Environmental barrier coatings (EBCs) are required for the use of silicon carbide (SiC)-based ceramic matrix composites (CMCs) in gas turbine engines, as they protect the SiO 2 thermally grown oxide (TGO) formed at the CMC/coating interface from volatilization in a combustion environment. Current-generation EBCs consist of a silicon bond coat and a rare earth (RE) silicate topcoat. The RE silicate topcoat is exposed to high-velocity steam during engine operation, and SiO 2 within the coating can preferentially volatilize to form Si(OH) 4 gas species, albeit at a lesser degree than SiO 2 alone. Therefore, it is of interest to investigate the stability of these materials in steam as a function of their RE. In this study, SiO 2 activity, which can be related to the partial pressure of Si(OH) 4 , was measured across the Gd 2 O 3 -SiO 2 phase diagram, which includes Gd 2 SiO 5 , Gd 9.33 (SiO 4 ) 6 O 2 , and Gd 2 Si 2 O 7 as line compounds, via Knudsen Effusion Mass Spectrometry (KEMS). Values obtained for the Gd 2 O 3 -SiO 2 system were compared to those of other RE2O3-SiO2 systems and contextualized in terms of EBC viability.

EBCs↗
NASA NTRSDate not supplied

Understanding the Durability of SiC Based Ceramic Matrix Composites (CMCs) for Gas Turbine Engine Hot Section Components

Silicon carbide fiber reinforced silicon carbide ceramic matrix composites (SiCf/SiC-CMCs) are being used in the fabrication of gas turbine engine hot section components due to their light weight and excellent thermal and chemical stabilities at high-temperature. These superior properties enable significant enhancements in engine efficiency and reduced fuel burn, emissions, and cooling requirements. In support of NASA’s Aeronautics Mission under various programs at Glenn Research Center, different types of composites have been developed and assessed for a high temperature (2700 °F) SiCf/SiC CMC system for turbine engine applications. These composites have creep-resistant SiC fibers, advanced 3D weaves, 2700 °F-capable hybrid SiC matrices, and durable environmental barrier coatings (EBCs). These efforts have resulted in improvements in the overall CMC thermomechanical and environmental durability. In order to study the role of different constituents and processing variables, a single fiber tow CVI (chemical vapor infiltration) SiC/SiC mini-composite can be considered the basic architectural feature of woven and laminate SiC/SiC CMCs. Moreover, the mini-composite mechanical and tensile creep damage behavior represents the creep behavior of 0° fiber tows in the axial loading direction of a macro-composite or component. In addition, a large number of mini-composite samples can be fabricated at relatively low cost within a short time, which makes them attractive for obtaining a robust set of experimental data and studying constituent behavior. In this presentation, the mini-composite approach to study damage mechanisms that limit CMC life in extreme environments including exposure to steam will be presented. The effects of constituent type and volume fraction on the CMC durability, which will help influence CMC design, will be discussed.

Ceramic Matrix Composites (CMCs)↗
NASA NTRS2023

Analysis of the Solid Products from the OSCAR and the AOWG Trash Processing Systems

Two trash conversion systems that process space logistical trash for conversion into gases and liquids have minor solid product formation consisting of primarily high carbon ash, inorganic salts, and aluminum metal flakes. These solid products necessarily comprise part of the system output because the thermal degradation processes intentionally operate at temperatures below aluminum vaporization and do not convert all solid inorganics or carbon-based compounds into gaseous compounds (i.e., CO 2 or CH 4 ). The two systems included the Orbital Syngas/Commodity Augmentation Reactor (OSCAR) combustion system funded by the NASA Space Technology Mission Directorate (STMD) located at NASA’s Kennedy Space Center, and the Advanced Organic Waste Gasifier (AOWG) steam reforming system developed by Pioneer Astronautics in Lakewood, Colorado, and funded by the NASA Small Business Innovation Research (SBIR) Exploration Systems Development Mission Directorate (ESDMD). OSCAR residual solids were collected from suborbital flight and ground-based laboratory testing, while all AOWG samples were collected from ground testing. This report discusses the solid product characterization, including elemental analyses performed with scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and a surface chemistry performed with x-ray photoelectron spectroscopy (XPS). A particle size analysis was performed with sieves, followed by SEM analyses. These analyses were performed to elucidate what high value products can be extracted or utilized from the solid products for follow on infusion into chemical feedstocks, manufacturing additives, or in-situ construction-based material needs.

OSCAR↗
NASA NTRS1965

Universal bellows joint restraint permits angular and offset movement

Universal joint-type restraint that employs ball joints permits maximum angular and lateral offset movement in a bellows joint without danger of rupture or pressure drop in the line. It is used in high pressure and high temperature applications in refineries, steam plants, or stationary power plants.

Kuhn, R. F., Jr.↗
NASA NTRS1967

Potassium plasma cell facilitates thermionic energy conversion process

Thermionic energy converter converts nuclear generated heat directly into high frequency and direct current output. It consists of a potassium plasma cell, a tantalum emitter, and a silver plated copper collector. This conversion process eliminates the steam interface usually required between the atomic heat source and the electrical conversion system.

Richards, H. K.↗
NASA NTRS1968

Conditioning flat conductors for flat conductor cable production

Apparatus can straighten, anneal, clean, and a tension to stretch a cable one percent to assure uniform cross-sectional area. A conductor passes through temperature controlled distilled water and through a toroid coil. As The conductor enters the water, steam performs the cleaning action. Quenching and annealing also take place.

Source record↗
NASA NTRS1969

Studies of cycles for liquid-metal magnetohydrodynamic generation of power

Studies of liquid-metal magnetohydrodynamic power cycles indicate that the overall efficiency of a binary cycle, employing a liquid-metal topping cycle and a bottoming steam cycle, may reach 60 percent. Details of analyses and data on cycles are presented, and the commercial potential of the binary cycle is discussed.

Lee, K.↗
NASA NTRS1969

Measurement of gas flow at extremely low pressures

Method accurately measures the flow of gases produced by evaporation or sublimation at pressures approaching total vacuum. Measurement of heat rejection in terms of flow of steam is taken with water as the liquid undergoing change in phase.

Bitterly, J. G.↗