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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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An analytical method was proposed for characterizing array power output, in the region of maximum power, as a function of environmental variables. The correlation provided a way of evaluating the output of an array under environmental conditions that differ from those encountered during testing. Power data obtained at one location was used to predict array performance at other locations.
High-power electric propulsion is a critical component of NASA s proposed missions to the outer planets. Mission studies have shown that high-power, high-specific-impulse propulsion systems can deliver 2000 kg of scientific payload to Pluto with trip times on the order of 10 years. Of greater significance is the ability of these propulsion systems to place this science payload in orbit around the planet, rather than making the fast fly-bys associated with traditional chemical propulsion systems. Significant ground test programs are required to develop the new technologies needed for thrusters operating at power levels exceeding 20 kW, an order of magnitude above the state of the art.
Electrode calendering is a necessary process used in industry to improve the volumetric capacity of lithium-ion batteries. However, calendering high-nickel cathodes leads to electrode particle pulverization, raising concerns of a reduced cycle life due to parasitic side reactions. We present here an investigation of the impact of calendering on the morphology and electrochemical performance of the cobalt-free layered oxide cathode LiNi 0.9 Mn 0.05 Al 0.05 O 2 (NMA-90). We find that secondary particle pulverization and fusion simultaneously occur at sufficiently high pressures. The initial surface area of the cathode is shown to increase with the degree of calendering, despite the higher likelihood of secondary particle fusion. Long-term cycling of full coin cells assembled with the NMA-90 cathode and the graphite anode indicates that cells with higher degrees of cathode calendering exhibit lower capacity fade compared to uncalendered cathodes. Hybrid pulse-power tests demonstrate that the usable capacity range of cells with calendered cathodes far exceeds those with uncalendered cells after long-term cycling. The improved capacity retention and pulse-power performance are attributed to the enhanced mechanical properties of the electrode after calendering that prevents loss of the primary particle contact during long-term cycling. As a result, we find that calendering high-nickel NMA-90 to industrially relevant densities does not have a detrimental effect on capacity fade, marking an important step toward commercial adoption.
The excess thermal energy produced by nuclear power plants (NPPs) during low electricity demands can be utilized in industrial processes, such as hydrogen production, through a thermal power dispatch (TPD) system. Initial testing of the first iteration of a single-train TPD design with a manual control mode at the Idaho National Lab (INL) revealed a high operator workload and degraded control capability. The current study evaluated the impact of an enhanced dual-train TPD design on operators’ subjective mental workload and evolution task-time while completing two operating scenarios in manual and automatic control modes. The results showed no statistically significant difference between participants’ mental workload using both control modes. Evolution time in automatic control mode took a shorter time than in manual control, with participants completing all evolutions in less than the 10-min set as the design specification limit. The shorter evolution time is discussed within the context of plant safety and operational efficiency.
The Rosemount X-STREAM Series X2GP is a paramagnetic oxygen analyzer with a 0-25% oxygen measurement range. It claims a drift less than 2% of span (0.10% volume oxygen) per week, and a response time of less than 5 seconds (for the analyzer to report 90% of a step change). Our test equipment was set-up such that the same gas was running through each oxygen analyzer at the same time. This allowed Calibration Error, Calibration Drift, and Loss of Power Testing to be run on all monitors at the same time, eliminating any variability between the analyzers from tolerances in the gas cylinder, ambient temperature, ambient pressure, test duration, etc. An APTech pressure regulator was placed on the gas cylinder manifold and a 23 psia Paroscientific pressure transducer measured the regulator’s outlet pressure. This did not give the inlet pressure on any one analyzer but outlet pressure from the manifold before the stream was split. The APTech pressure regulator was used to keep operating conditions consistent. A DWYER rotameter was installed on each oxygen monitor’s outlet piping. With the exception of Variation of Flow Rate Testing, the rotameter was left fully open for all testing. The flow rate through each oxygen monitor was controlled by a Swagelok needle valve that was installed on each analyzer’s inlet piping. Additionally, a filter was installed in the each monitor’s inlet piping to keep particles from the measurement cells and a Swagelok ball valve was installed on each monitor’s outlet piping to isolate each monitor between tests. No pumps were installed. Each of the cylinders used was at a pressure greater than ambient room barometric pressure. This pressure differential was used to move gas through the testing equipment. The flow rate through each analyzer was controlled by the Swagelok needle valve installed on each analyzer’s inlet piping. Finally, for all tests, a Paroscientific Digiquartz Barometer was used to measure ambient room barometric pressure and a Fluke Thermo-hygrometer was used to measure ambient room temperature.
As a part of the Open Energy Data Initiative, this effort aims to develop and demonstrate novel distribution state estimation, control optimization, and transient analysis as well as provide access to data, data integration, and mapping information. More specifically, the focus of the effort will be on physics-based distribution system state estimation, hybrid (physics-based and machine learning) distribution optimal power flow, and event detection/analysis for solar integration and analytics. This work will enable reproducible, robust, replicable, and generalizable R&D in simulation and emulation of solar system integration. These test models and datasets will provide an integrated library for developing and testing power system operation technologies. To make the library user-friendly, this project will provide data curation tools such as data translators, mapping scripts and APIs, database schemas and metadata, interfaces and user dashboard, source code for the reference algorithms, description of the use-cases/scenarios, and comprehensive information on all the assumptions.
Well-trained classifiers and their complete weight distributions provide us with a well-motivated and practicable method to test generative networks in particle physics. We illustrate their benefits for distribution-shifted jets, calorimeter showers, and reconstruction-level events. In all cases, the classifier weights make for a powerful test of the generative network, identify potential problems in the density estimation, relate them to the underlying physics, and tie in with a comprehensive precision and uncertainty treatment for generative networks.
This paper describes an experimental study to investigate the effectiveness of using thermoelectric converters (TECs) to control the loop heat pipe (LHP) operating temperature. Tests were conducted on an LHP having two evaporators and two condensers. Each evaporator has its own integral compensation chamber (CC). One side of the TEC is attached to the CC, and the other side is connected to the evaporator through a copper thermal strap. A bi-polar power supply is used to provide the power for the operation of each TEC. The bipolar supply will automatic change the direction of the current to the TEC depending on whether the CC requires heating or cooling in order to maintain its temperature at the desired set point. When cooling the CC, the heat pumped by the TEC plus the power needed to operate the TEC is dissipated to the evaporator, and is ultimately transmitted to the condenser. When heating the CC, the TEC can draw heat from the evaporator to supplement the required control heater power. Test results showed that the TEC could control the LHP operating temperature within h1K of the set point temperature. The control heater power required for TEC operation was also much less than that of using electrical heaters.
Abstract not provided.
In the Phase I program, Calabazas Creek Research, Inc. (CCR), in collaboration with North Carolina State University (NCSU), fabricated copper accelerator cavities and used Atomic Layer Deposition (ALD) to apply thin metal coatings of tungsten and platinum. It was hypothesized that a tungsten coating would provide a robust surface more resistant to arcing and arc damage. The platinum coating was predicted to reduce processing time by inhibiting oxides that form on copper surfaces soon after machining. Two sets of cavity parts were fabricated. One was coated with 35 nm of tungsten, and the other with approximately 10 nm of platinum. Only the platinum cavity parts could be high power tested during the Phase I program due to schedule and funding constraints. The platinum coated cavity exhibit poor performance when compared with pure copper cavities. Not only did arcing occur at lower power levels, but the processing time was actually longer. There were several issues that contributed to the poor performance. First, machining of the base copper cavity parts failed to achieve the quality and cleanliness standards specified to SLAC National Accelerator Center. Secondly, the ALD facilities were not configured to provide the high levels of cleanliness required. Finally, the nanometer coating applied was likely far too thin to provide the performance required. The coating was ablated or peeled from the surface in regions of high fields. It was concluded that the current ALD process could not provide improved performance over cavities produced at national laboratories using dedicated facilities.
Six wing models were tested in the Langley Unitary Plan Wind Tunnel to identify and study leading-edge thrust at supersonic speeds. The tests were conducted at Mach numbers of 1.6, 1.8, 2.0, and 2.16, at a stagnation temperature of 125.0 F, and at Reynolds numbers per foot of 2.0 x 10 to the 6th power and 5.0 x 10 the 6th power. Test results showed that significant benefits from leading-edge thrust and nonlinear thickness effects can be obtained with very little airfoil bluntness, that these benefits were lost when the airfoil was severely blunted, and that such benefits seem to be found on wings with supersonic as well as subsonic leading edges.
The Cryomodule Test Stand (CMTS1) at Fermilab has been engaged with testing 8-cavity 1.3 GHz cryomodules designed and assembled for the LCLS-II project at SLAC National Accelerator Laboratory since 2016. Over these three years twenty cryomodules have been cooled to 2K and power tested in continuous wave mode on a roughly once per month cycle. Test stand layout and testing procedures are presented together with results from the cryomodules tested to date. Lessons learned and future plans will also be shared.
Microtron-based Compact, Portable Gamma-Ray Source. The objective of Phase I of this project was to produce a conceptual design of a prototype compact microtron electron accelerator, which could be designed, built, and demonstrated in Phase II of the project. The conceptual design study included an analysis of the parameters of the microtron and its components, and the expected performance of the prototype microtron as a source of x-rays and/or RF neutrons in the MeV energy range. The major components of the microtron are the magnet, the accelerating system, the power system, the vacuum system, the control system, the beam extraction system and the targets to produce x-rays (and/or neutrons). Our objectives for the design of the prototype were for it to be compact, cost-effective, capable of producing high intensity x-ray (an/or neutron) fluxes. In addition, the prototype was to be easily assembled and disassembled so that components could be easily replaced. The main parameters for the prototype are the following: the range of electron kinetic energies, the output power, the RF frequency band (X-band, C-band, or S-Band), the type of injection (Type I or Type II), the magnet type, i.e. permanent magnet, electromagnet, or a hybrid combination of permanent and electromagnet. The results of the Phase I study and analysis for a prototype microtron are the following: The electron energy range can be varied from below 6 MeV to 9 MeV, the optimal frequency range is S-Band (2-4 GHz) RF frequency, Type II injection (described below), and the magnet type is the hybrid version. The prototype version will be capable of producing gamma ray doses of ~1800 R/min-m and neutron fluxes of up to ~6 x 10 10 n/s with appropriate targets. The results of the Phase I study and analysis are provided below. The proposed Phase II plan was to demonstrate the prototype at low beam power. In the subsequent Phase III, high power tests would be performed, and the design of commercial versions of microtrons with various energies, sizes and types would be produced and marketed, including a more compact and more portable 6 MeV battery-powered model that more closely meets the requirements in the original FOA topic description. In the course of the Phase I study, we also identified another microtron version, one that was larger (not compact) and more powerful than that of the Phase II prototype, which could serve as an intense source of photo- neutrons, up to 4 x 10 12 n/s for use in nuclear medicine, short-lived isotope production, or other applications. In addition, it could produce gamma dose rates up to 130 kR/min-m with a heavy metal bremsstrahlung target. The results and specifications of this were submitted to IPAC16 (Reference [12]) the paper is included in Addendum B. Because this version was beyond the scope of the Phase I project, there is no additional description in the Final Report.
The results of reactor tests of a carbonitride fuel in a single-crystal cladding from a molybdenum-based alloy can be used in substantiating the operational reliability of fuels in developing a project of a megawatt space nuclear power plant. The results of experimental studies of uranium and cesium penetration into the single-crystal cladding of fuel elements with a carbonitride fuel are interpreted. Those fuel elements passed nuclear power tests in the Ya-82 pilot plant for 8300 h at a temperature of about 1500°C. It is shown that the diffusion coefficients for uranium diffusion into the cladding are virtually coincident with the diffusion coefficients measured earlier for uranium diffusion into polycrystalline molybdenum. It is found that the penetration of uranium into the cladding is likely to occur only in the case of a direct contact between the cladding and fuel. The experimentally observed nonmonotonic uranium-concentration profiles are explained in terms of predominant uranium diffusion along grain boundaries. It is shown that a substantially nonmonotonic behavior observed in our experiment for the uranium-concentration profile may be explained by the presence of a polycrystalline structure of the cladding in the surface region from its inner side. The diffusion coefficient is estimated for the grain-boundary diffusion of uranium. The diffusion coefficients for cesium are estimated on the basis of experimental data obtained in the present study.
Results are presented of free-jet tests of a 1.1-inch-diameter hydrogen-burning ram-jet engine over a Mach number range from 1.42 to 2.28 and a Reynolds number range from 6.01 times 10 to the 6th power to 15.78 times 10 to the 6th power. Tests demonstrated the reliability and wide operating range of the engine and showed its suitability for installation on wind-tunnel models of airplane and missile configurations. A comparison of engine operation with combustion-chamber lengths of 3.33 and 1.51 engine diameters was made at a Mach number of 2.06. A maximum test thrust coefficient of 0.905 was obtained at fuel-air ratio of 0.034 and a Mach number of 2.06 for the engine with the 3.33-diameter combustion chamber.
Results are presented from two separate tests on the same blended wing-body hydrogen fueled transport model at a Mach number of about 8 and a range of Reynolds numbers (based on theoretical body length) of 0.597 x 10 to the 6th power to about 156.22 x 10 to the 6th power. Tests were made in conventional hypersonic blowdown tunnel and a hypersonic shock tunnel at angles of attack of -2 deg to about 8 deg, with an extensive study made at a constant angle of attack of 3 deg. The model boundary-layer flow varied from laminar at the lower Reynolds numbers to predominantly turbulent at the higher Reynolds numbers. Model wall temperatures and stream static temperatures varied widely between the two tests, particularly at the lower Reynolds numbers. These temperature differences resulted in marked variations of the axial-force coefficients between the two tests, due in part to the effects of induced pressure and viscous interaction variations. The normal-force coefficient was essentially independent of Reynolds number. Analysis of results utilized current theoretical computer programs and basic boundary-layer theory.
The National Transonic Facility is a transonic pressurized cryogenic facility. The development of the high Reynolds number semi-span capability has advanced over the years to include transonic active flow control and powered testing using the sidewall model support system. While this system can be used in total temperatures down to -250Â F for conventional unpowered configurations, it is limited to temperatures above -60Â F when used with powered models that require the use of the high-pressure air delivery system. Thermal instabilities and non-repeatable mechanical arrangements revealed several data quality shortfalls by the force and moment measurement system. Recent modifications to the balance cavity recirculation system have improved the temperature stability of the balance and metric model-to-balance hardware. Changes to the mechanical assembly of the high-pressure air delivery system, particularly hardware that interfaces directly with the model and balance, have improved the repeatability of the force and moment measurement system. Drag comparisons with the high-pressure air system removed will also be presented in this paper.
Desigg and performance of SNAP-8 nuclear reactor simulator for nonnuclear testing of space power systems