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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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188 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Exploring the Effect of EBC Composition on CMAS Wetting Behavior

Rare-earth disilicate (REDS) materials are existing materials used in environmental barrier coating (EBC) for the protection of structural materials in the hot-section of turbine engines. REDS interactions with molten calcium-magnesium-aluminosilicate (CMAS) debris are of interest to understand molten CMAS attack and improve CMAS mitigation strategies. This work assesses the effect of REDS composition on CMAS wetting by investigating wetting angle, spreading, and reactivity. Freestanding atmospheric plasma spray (APS) REDS coatings (for RE = Y, La, Nd, Gd, Yb, Lu) were exposed to 10 mg of CMAS (Ca33-Mg9-Al13-Si45 in single cation mol%) in stagnant lab air at 1250C. APS YbDS was compared to a dense spark plasma sintered (SPS) phase-pure Yb2Si2O7 and a nominal 20 vol% phase-mixture of Yb 2 SiO 5 in Yb 2 Si 2 O 7 (20YbMS/YbDS). CMAS mass was held constant but specimen surface areas varied, yielding a range of loading between ~6 and 10 mg/cm2. CMAS was loaded as a cylindrical rod atop the specimen surface, polished to 4000 grit, and heated to temperature in a Linseis L74/HS/1700 heating microscope. The heating microscope measured the evolution of molten CMAS diameter, height, and contact angle. Molten CMAS diameter at 1150C and contact angle measurements after two hours of exposure at 1250C yielded a positive trend with rare-earth cation size. There was no statistically significant difference in CMAS wetting behavior between SPS YbDS and 20YbMS/YbDS. Post-exposure specimens were examined in plan view and cross-section with XRD, SEM, and EDS. CMAS spreading was cross-examined using plan view SEM, while reactivity utilized plan view XRD and cross-sectional SEM/EDS.

Clark Luckhardt↗
NASA NTRSDate not supplied

Maintenance Modernization in the Era of Artemis An RCM Journey

The NASA Artemis Program mission to return humans to the moon requires it ground test facilities to meet today’s performance and throughput demands. The NASA Ames Arc Jet Complex (AJC) at Ames Research Center is the Agency’s sole ground test facility supporting reentry thermal protection system testing and was developed to support Apollo era spacecraft. The research and development required to meet current and future mission demands continually grows, but the maintenance upkeep to ensure safe and reliable operations holds stagnant. This paper presents the journey and subsequent industry relatable story that includes the challenges, lessons learned, and testimonials to the AJC’s approach to the modernization of maintenance using RCM at NASA.

Reliability Centered Maintenance↗
DOE OSTI2021

Updated weather model captures subtleties of cold-air pool events

Imagine cold air building up inside a valley or other topographic basin, like a cold swimming pool in the atmosphere. Known in meteorology as cold-air pools, or simply cold pools, these events affect wind plant power production in two key ways. Because they are associated with stagnant air and low winds near the ground, cold pools can severely limit wind energy output over periods of hours to days. Then, when cold pools dissolve, known as cold pool “erosion,” increased wind speeds allow wind power production to recover.

Energy↗
DOE OSTI2022

Thermal-hydraulic and Fuel Performance Scoping Studies of a Flowing Water Capsule in TREAT

The restart of the Transient Reactor Test (TREAT) facility has provided a much needed capability for integral transient testing of nuclear fuel. This testing is necessary to qualify new fuel concepts such as those developed under the Accident Tolerant Fuel (ATF) program, increasing the burnup limit of light water reactor (LWR) fuels, or a variety of other programs under the Advanced Fuels Campaign (AFC). The ATF campaign has been the main driver behind the development and implementation of a variety of capsules for TREAT experiments. The Separate-Effect Test Holder (SETH) was a dry capsule that enabled testing of ATF concepts under reactivity-initiated accident (RIA) heating conditions. Following SETH, the Static Environment Rodlet Transient Test Apparatus (SERTTA) was developed to enable RIA testing in a static water environment. In efforts to support the need for future Loss-of-Coolant Accident (LOCA) tests, the Transient Water Irradiation System for TREAT (TWIST) capsule has been developed that allows for water to drain from around the fuel rod and lower the pressure to simulate LOCA conditions. All these capsules that have been developed for LWR fuel testing all lack the capability for forced convective cooling which in some applications may limit their ability to test under prototypic conditions. A design and modeling effort has been started to modify the TWIST capsule by adding a flow tube and impeller that can create flowing coolant conditions for the fuel rod. RELAP5-3D and BISON models are being used to study the differences between RIA, LOCA, Anticipated Operational Occurrences (AOO), LWR power cycling, and other transient scenarios under flowing conditions capable in the flowing capsule and the current stagnant water capsules (SERTTA and TWIST). The scoping study will provide guidance on the needed capabilities for the flowing capsule and the limitations of the currently developed capsule for LWR testing in TREAT.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Combustion studies of n-butyl acetate synthesized by a new biological process and comparisons with neat n-butyl acetate

Blending petroleum fuels with biofuels is a common approach for stemming the depletion of crude oil while also mitigating the impact of their combustion on the environment. It has recently been considered that n-butyl acetate (BA, C6H12O2, boiling point of 399K) could be a viable biofuel additive to diesel fuel. This paper reports the combustion dynamics of BA droplets in the absence of external convection. Two grades of BA were examined: one synthesized by a new process that uses a solventogenic Clostridium strain through an extractive fermentation process using n-hexadecane as the extractant (SBA); the other commercially available as a high-purity (99.9%) 'neat' BA grade produced by Fischer esterification (NBA). The mass concentration of by-products from the synthesis process amounted to approximately 6% of the total composition and included n-butanol, n-hexadecane, iso-propyl alcohol and ethyl acetate. The platform used to study the combustion of commercial and synthesized BA was an isolated droplet burning with spherical symmetry. Initial droplet diameters were fixed at 0.6 mm. Experiments were carried out in a drop tower to promote one-dimensional transport dynamics, in the standard atmosphere, and with ignition accomplished by spark discharge. Differences in droplet burning rates and flame structures were undetectable between NBA and SBA, despite the differences in burning among the SBA components individually. The results presented show that the new synthesis process for butyl acetate yields a sustainable alternative to conventional methodologies with burning characteristics that are identical to NBA in stagnant gas transport fields.

Wang, Yujie↗
DOE OSTI2022

Thin Triples Expand the Affordable High-Performance Window Options For Retrofit

Sales of high-performance triple-pane windows make up only a small fraction (~3%) of total window sales in the United States with relatively stagnant market growth over the past 20 years. High costs have been the most commonly cited barrier to adoption. The emergence of thin triples that can fit into the glazing pocket of existing double pane windows has the potential to revolutionize the high-performance window market in particular the retrofit market by enabling glass only upgrades for situations where the frames are still in good condition. The retrofit market has other unique challenges not found in new construction that can be solved or reduced by thin triple pane windows. Insert replacements are often pursued instead of full frame replacement, in retrofits, this method reduces the net free area of a window and can turn an egress window into one that no longer meets the net free area requirements for egress. Thin frames minimize such occurrences. However, these thin frames can often not accommodate the weight of a traditional triple pane, thin triples can bring high performance to this situation. Thicker frames can also increase retrofit labor costs because the interior drywall and/or trim molding needs to be cut back to accommodate a thicker frame while thin triples can fit into frames that match the thickness of the existing window. This paper presents information about field test experiences the highlight these retrofit advantages from experiencing the challenges associated with retrofitting a thick frame as well as the supply chain, purchasability, material and labor costs, and real-world energy and non-energy performance associated with the IGU only replacement method.

window retrofits, thin triple-pane windows, high p↗
DOE OSTI2020

Vertical Transport of Water/Contaminant Due to Intermittent Water Influx on the Ground Surface of Vadose Zone - 20088

For movement of moisture and transport of contaminants in the vertical direction, two equations, the Richards equation and the advection-dispersion equation, are solved in a vadose zone for prescribed water and contaminant influx conditions at the ground surface. Two different boundary conditions are considered, one with a single peak of sinusoidal variation and four peaks of finite duration, each of which is sinusoidal in shape. The moisture migration is solved and then the contaminant transport, which is coupled to moisture movement, is solved. In the case of a single influx on the ground surface, at first the hydraulic head and moisture content show a peak. Then above the peak and below the ground surface, the peaks tend to die out, showing a tendency to return to the initial state. The vertical profile of concentration also shows a single peak, which soon becomes stagnant because downward water migration is faster than concentration profile movement. In the case of four intermittent array of peaks, the hydraulic head and moisture content profiles tend to merge and combine together. The concentration profiles show appearance of four peaks clearly. However, although the peak value of concentration remains quite constant, the values may vary with the sorption coefficient because of repeated influx of water and contaminant through the top boundary, the ground surface. The penetration depth decreases with an increasing sorption coefficient. (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Fuel Performance Evaluation of THOR-C Experiments

The Temperature Heatsink Overpower Response Commissioning (THOR-C) and THOR-Metal (THOR-M) experiments will be performed as part of an ongoing project for testing sodium fast reactor fuels with the Japan Atomic Energy Agency (JAEA). The THOR-C experiments consist of fresh metallic fuel pins and have been analyzed using the ABAQUS, Ansys codes and the BISON fuel performance code. THOR-M-Loss of Flow-1 (THOR-M-LOF-1) is designed to test an EBR-II irradiated fuel pin under LOF conditions. Simulation of the THOR-MLOF-1 experiment required first simulating the base irradiation of the fuel pin in EBR-II. MFUEL module of SAS4A/SASSYS-1 [1] is a physics-based metallic fuel performance model applicable to the normal operation, transient scenarios and fuel failure modeling including scenarios with bulk fuel melting. The model has been validated using EBR-II normal operation, separate effect transient tests as well as TREAT M-Series transient tests [2]. In this study, MFUEL models has been utilized together with a new capsule heat transfer model developed in this project. The new heat transfer model was necessary due to (1) significant amount of heat losses that required 2D heat transfer, (2) the presence of a titanium heat sink, rejecting a significant amount of heat, and (3) stagnant coolant conditions, which are inconsistent with SAS4A/SASSYS-1 (SAS) heat transfer model. Updates to SAS4A/SASSYS-1 and MFUEL has been described below, followed by a preliminary validation effort using the results from THOR-C-2 fresh fuel capsule experiment. A previous study for THOR-C-2 analysis using BISON code is also utilized in this study to model this test [3]. [1] D. O’Grady, A. J. Brunett, L. Ibarra, A. Karahan, T. Kim, T. S. Sumner, R. Thomas, T. H. Fanning, “The SAS4A/SASSYS-2 Version 5.7 Safety Analysis Code System,” Argonne National Laboratory,ANL/NSE-SAS/5.7, (2023). [2] A. Karahan, T. Kim, T. Fanning, D. O’Grady, “Validation of MFUEL Metal Fuel Performance Models of SAS4A/SASSYS-1,” Argonne National Laboratory, ANL/NSE-23/11, (2023). [3] M. Mihelish, A. Zabriskie, K. Paaren, P. Medvedev, C. Jensen, “Fuel Performance Predictions for the TREAT THOR-C Experiments,” Idaho National Laboratory, INL/RPT-23-73397, Revision 0, (2023)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗