Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “high loading”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Co-optimized Mixed-Mode Engine and Fuel Demonstrator for Improved Fuel Economy while Meeting Emissions Requirements

Progressively increasing regulatory demands on fuel economy and future global emission standards have led to a focus on advanced engine development to improve overall engine efficiency and fulfill emission requirements. Low temperature combustion (LTC) and gasoline compression ignition (GCI) are promising technologies to achieve these goals and have the advantage of using existing refinery infrastructure and subsequent economies of scale for a robust energy supply. By applying spark ignition (SI) for cold start, LTC for low load operations, and GCI for medium to high load operations, a multimode GCI engine concept was proposed and the fuel formation was co-optimized to maximize fuel economy improvement potential while maintaining ULEV 70 emissions standards. HATCI has successfully demonstrated the feasibility of this multimode GCI engine concept, and confirmed the fuel economy improvement over the baseline SI engine by simulating the FTP75 vehicle drive cycle. In this report, the technical approaches, multimode engine control, and engine test results of both steady state and transitions, CFD modeling, fuel testing, and FTP75 drive cycle simulation results are summarized, followed with technical challenges observed, and recommendations for possible follow-up studies.

02 PETROLEUM↗
NASA NTRS1947

Investigation of Axial-flow Fan and Compressor Rotors Designed for Three-dimensional Flow

An investigation has been conducted to determine whether three-dimensional flows may be utilized in axial-flow fan and compressor rotors so that the spanwise load distribution may be varied to obtain high pressure rise. Two rotors, one with approximately uniform and one with solid-body downstream tangential-velocity distributions, were designed and tested at the design blade angle. Radial surveys of total pressure, static pressure, and flow angle were made upstream and downstream of the test rotors through a quantity-coefficient range. Tests of the solid-body rotor were also conducted at a large value of tip clearance. The results indicated that the three-dimensional flows may be utilized with high efficiency and that the three-dimensional theory used in conjunction with two-dimensional cascade data is sufficiently accurate for design purposes. The tests also showed that the tip-clearance losses of rotors highly loaded at the tips are not excessive. The existing three-dimensional theory in simplified for and an illustrative rotor design are presented in appendixes.

Kahane, A↗
DOE OSTI2022

Pinned Electrode/Electrolyte Interphase and Its Formation Origin for Sulfurized Polyacrylonitrile Cathode in Stable Lithium Batteries

Sulfurized polyacrylonitrile (SPAN) represents one of the most promising directions for high-energy-density lithium (Li)-sulfur batteries. However, the practical application of Li||SPAN is currently limited by the insufficient chemical/electrochemical stability of electrode/electrolyte interphase (EEI). Here, a pinned EEI layer is designed for stabilizing a SPAN cathode by regulating the EEI formation mechanism in an advanced LiFSI/ether/fluorinated-ether electrolyte. Computational simulations and experimental investigations reveal that, benefiting from the nonsolvating nature, the fluorinated-ether can not only act as a protective shield to prevent the Li polysulfides dissolution but also, more importantly, endow a diffusion-controlled EEI formation process. It promotes the formation of a uniform, protective, and conductive EEI layer pinning into SPAN surface region, enabling the high loading Li||SPAN batteries with superior cycling stability, wide temperature performance, and high-rate capability. Finally, this design strategy opens an avenue for exploring advanced electrolytes for Li||SPAN batteries and guides the interface design for broad types of battery systems.

25 ENERGY STORAGE↗
DOE OSTI2023

Insights into the Chemistry of the Cathodic Electrolyte Interphase for PTFE-Based Dry-Processed Cathodes

Dry processing is a promising method for high-performance and low-cost lithium-ion battery manufacturing which uses polytetrafluoroethylene (PTFE) as a binder. However, the electrochemical stability of the PTFE binder in the cathodes and the generated chemistry of the cathode electrolyte interphase (CEI) layers are rarely reported. In this work, the CEI properties and PTFE electrochemical stability are studied via cycling the high-loading dry-processed electrodes in electrolytes with LiPF 6 or LiClO 4 salt. Using LiClO 4 salt can eliminate other possible F sources, allowing the decomposition of PTFE to be studied. The detection of LiF in cells with the LiClO 4 salt confirms that PTFE undergoes side reaction(s) in the cathodes. When compared with LiClO 4 , the CEI layer is much thicker when LiPF 6 is used as the electrolyte salt. These results provide insights into the CEI layer and may potentially enlighten the development of binders and electrolytes for the high efficiency and long durability of DP-based LIBs.

25 ENERGY STORAGE↗
DOE OSTI2025

Dynamic Strength and Equation of State of Epon 828 and Diethanolamine (DEA) Polymer Epoxy Under Shock Loading

Polymers are increasingly utilized in engineering applications that can experience high loading rates, necessitating increased understanding of their response under such conditions. The tamped Richtmyer-Meshkov Instability (RMI) method was used to characterize the equation of state and dynamic strength of the polymer Epon 828 cured with Diethanolamine (DEA). Plate impact experiments that drove a uniaxial shock compression wave across a sinusoidally corrugated metal-polymer interface were performed to generate shock stresses from 4-12 GPa and strain rates of approximately 1/s in the polymer. X-ray phase contrast imaging recorded the shock motion in the polymer and subsequent interface evolution. Analysis of this data yielded the polymer equation of state and, in conjunction with numerical modeling, the dynamic strength. The equation of state was validated against one-dimensional plate impact experiments from existing literature. The dynamic strength was compared to prior data for Epon 828 and related polymers at lower strain rates and found to exhibit significant strain rate and pressure-hardening effects. The strength of the Epon 828 polymer at 10 6 1/s was found to be approximately 1.5 GPa, suggesting that it is comparable to the strength of high strength metals at these dynamic conditions.

Equation of state↗
DOE OSTI2023

High-throughput and high-performance lithium-ion batteries via dry processing

A scalable powder-to-electrode dry processing strategy mainly based on powder dry mixing and rolling/calendering is rationally designed. The dry processed electrodes show lower tortuosity compared to that of conventional slurry-based electrodes. The dry-processed high-loading graphite anodes (6.6 mAh cm -2 ) and LiNi 0.6 Mn 0.2 Co 0.2 O 2 cathodes (6.0 mAh cm -2 ) exhibit promising electrochemical performance in half-cells and full-cells. The full-cells with both electrodes from dry processing demonstrates superb rate performance to their counterpart with conventional slurry-based electrodes and delivers of capacity retentions of 74.1 % and 63.6 % over 400 and 800 cycles, respectively. Notably, the initial Coulombic efficiency of the dry processed graphite anodes is low ascribed to polytetrafluoroethylene binder. Finally, the results suggest that dry processing is promising for future lithium-ion battery manufacturing and also pinpoint the needs of modification for the polytetrafluoroethylene binder in the graphite anodes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Composite binder, processing, and particle size effects on mechanical properties of non-hazardous high explosive surrogates

Plastic-bonded explosives (PBX) are polymer matrix composites that are highly loaded with micron-scale explosive crystals. The thermal and mechanical properties of these materials must be well-understood so that appropriate engineering models can be developed, but testing such properties under many scenarios can be hazardous and expensive. A non-hazardous PBX surrogate (“mock”) may be used in place of a PBX in many experiments if the thermomechanical properties are well-matched. Our previous research has shown that 5-iodo-2'-deoxyuridine (IDOX) is a promising crystalline filler material for the explosive cyclotetramethylene-tetranitramine (HMX). In this study, we investigate how the binder composition, variations in the IDOX particle size distribution, and pressing temperature affect the compressive strength and elastic modulus. We observe that while the binder system used in the composite dominates the mechanical response, the particle size distribution and pressing conditions do have a measurable effect on the material compliance and strength.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2021

Optimization of Magnesium‐Doped Lithium Metal Anode for High Performance Lithium Metal Batteries through Modeling and Experiment

Abstract Lithium (Li)‐magnesium (Mg) alloy with limited Mg amount, which can also be called Mg‐doped Li (Li‐Mg), has been considered as a potential alternative anode for high energy density rechargeable Li metal batteries. However, the optimum doping‐content of Mg in Li‐Mg anode and the mechanism of the improved performance are not well understood. Herein, density functional theory (DFT) calculations are used to investigate the effect of Mg amount in Li‐Mg anode. The Li‐Mg with about 5 wt. % Mg (abbreviated as Li‐Mg5) has the lowest absorption energy of Li, thus all the surface area can be “controlled” by Mg atoms, leading to the smooth and continuous deposition of Li on the surface around the Mg center. A localized high concentration electrolyte enables Li‐Mg5 to exhibit the best cycling stability in Li metal batteries with high‐loading cathode and lean electrolyte under 4.4 V high‐voltage, which is approaching the demand of practical application. This electrolyte also helps generate an inorganic‐rich solid electrolyte interphase, which leads to smooth, compact and less corrosion layer on the Li‐Mg5 surface. Both theoretical simulations and experimental results prove that Li‐Mg5 has optimum Mg content and gives best battery cycling performance.

Gao, Peiyuan↗
DOE OSTI2025

Mechanically Robust Bismuth-Embedded Carbon Microspheres for Ultrafast Charging and Ultrastable Sodium-Ion Batteries

Advancements in the development of fast-charging and long-lasting microstructured alloying anodes with high volumetric capacities are essential for enhancing the operational efficiency of sodium-ion batteries (SIBs). These anodes, however, face challenges such as declined cyclability and rate capability, primarily due to mechanical degradation reduced by significant volumetric changes (over 252%) and slow kinetics of sodium-ion storage. Herein, we introduce a novel anode design featuring densely packed bismuth (Bi) embedded within highly conductive carbon microspheres to overcome the aforementioned challenges. Remarkably, the high loading Bi anode within carbon microspheres with a high tap density of 2.59 g cm -3 possesses significant mechanical strength exceeding 590 MPa and limits volume swelling of only 10.9% post-sodiation. This anode demonstrates a high volumetric capacity (908.3 mAh cm -3 ), ultrafast chargeability (200 A g -1 , full charge/discharge in just 5.5 s), and outstanding cyclability over 12,000 cycles and maintains exceptional cycling stability even at -30 °C. The full cell paired with a Na 3 V 2 (PO 4 ) 3 cathode retains over 80% capacity after 600 cycles at 36 C, demonstrating a remarkable rate capability of 126 C (full charge/discharge in 28.6 s). Our comprehensive experimental evaluations and chemo-mechanical simulations shed light on the mechanisms underpinning the anode's superior performance. In conclusion, this development marks a significant advancement in the design of durable and fast-charging anodes for high-performance SIBs.

25 ENERGY STORAGE↗
DOE OSTI2023

Low Impedance Cathode/Electrolyte Interfaces for High Energy Density Solid-State Batteries

All-solid-state batteries (ASSBs) using a ceramic fast Li-ion conductor as a solid-state electrolyte (SSE) have been proposed as a promising strategy to significantly increase the energy density of lithium batteries. Due to their high ion conductivity and excellent stability, Li-stuffed garnets exhibit the most promising physical and chemical properties for SSEs. However, the typical microstructure, thick (>100 μm) bulk electrolyte and simple planar electrode/electrolyte interfaces, combined with poor electrode wetting of the garnet result in excessively high area specific resistances (ASRs) that severely limit achievable current density and cell energy density. In this project, the team is building on their demonstrated expertise with garnet electrolytes and ASSBs to accomplish the following: (1) engineer interfaces to overcome high NMC/LLZ interfacial impedance and interfacial degradation; (2) develop processing and fabrication techniques to achieve high loading NMC/LLZ composite cathodes with low resistance and high cyclability; and (3) integrate the NMC/LLZ cathodes into all-solid-state Li-metal/LLZ cells to achieve high-energy-density batteries.

25 ENERGY STORAGE↗
NASA NTRS2003

Effects on Diagnostic Parameters After Removing Additional Synchronous Gear Meshes

Gear cracks are typically difficult to diagnose with sufficient time before catastrophic damage occurs. Significant damage must be present before algorithms appear to be able to detect the damage. Frequently there are multiple gear meshes on a single shaft. Since they are all synchronous with the shaft frequency, the commonly used synchronous averaging technique is ineffective in removing other gear mesh effects. Carefully applying a filter to these extraneous gear mesh frequencies can reduce the overall vibration signal and increase the accuracy of commonly used vibration metrics. The vibration signals from three seeded fault tests were analyzed using this filtering procedure. Both the filtered and unfiltered vibration signals were then analyzed using commonly used fault detection metrics and compared. The tests were conducted on aerospace quality spur gears in a test rig. The tests were conducted at speeds ranging from 2500 to 5000 revolutions per minute and torques from 184 to 228 percent of design load. The inability to detect these cracks with high confidence results from the high loading which is causing fast fracture as opposed to stable crack growth. The results indicate that these techniques do not currently produce an indication of damage that significantly exceeds experimental scatter.

Decker, Harry J.↗
NASA NTRS2010

The Effect of a Non-Gaussian Random Loading on High-Cycle Fatigue of a Thermally Post-Buckled Structure

High-cycle fatigue of an elastic-plastic beam structure under the combined action of thermal and high-intensity non-Gaussian acoustic loadings is considered. Such loadings can be highly damaging when snap-through motion occurs between thermally post-buckled equilibria. The simulated non-Gaussian loadings investigated have a range of skewness and kurtosis typical of turbulent boundary layer pressure fluctuations in the vicinity of forward facing steps. Further, the duration and steadiness of high excursion peaks is comparable to that found in such turbulent boundary layer data. Response and fatigue life estimates are found to be insensitive to the loading distribution, with the minor exception of cases involving plastic deformation. In contrast, the fatigue life estimate was found to be highly affected by a different type of non-Gaussian loading having bursts of high excursion peaks.

Rizzi, Stephen A.↗
DOE OSTI2026

Data-Driven Modeling of High-Resolution Residential Load Profiles Using Low-Resolution Smart Meter Measurements

Accurate and high-resolution residential load profiles are essential for power system modeling, demand response planning, and effective grid operation. As the energy sector moves towards a more actively managed distribution system, the ability to understand residential energy consumption at a minute-by-minute scale becomes increasingly critical. High-resolution load profiles provide key insights into demand patterns and user behavior, enabling grid operators to design more effective energy solutions; however, residential load measurements in the field are typically recorded at low resolutions, such as 15-60 minutes, which makes it hard to study the characteristics of different residential customers. This paper addresses these challenges by introducing a data-driven approach to generate realistic, high-resolution residential load profiles based on lowre-solution measurements and weather information. The proposed method retains the key features of the actual residential load measurements while offering appliance-level energy consumption details for each residential building. The results demonstrate the effectiveness of the proposed load profile generator, proving its capability to support utilities in optimizing residential energy management and ensuring a more reliable and resilient grid.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1991

Thermoviscoplastic response of Ti-15-3 under various loading conditions

Metal matrix composites (MMC's) are candidate materials for use in high temperature, high loading applications. In particular, an MMC consisting of a titanium alloy reinforced with silicon-carbide fibers is being considered for use on the National Aerospace Plane (NASP). Compared to other metals and metallic alloys, titanium alloys retain relatively high stiffness, strength, and corrosion resistance at elevated temperatures. However, above roughly 316 C titanium exhibits a significant thermoviscoplastic (creep) response. Since the temperatures encountered in many regions of the NASP are expected to exceed 316 C, the potential thermoviscoplastic behavior of titanium-based MMC's at elevated temperatures must be thoroughly investigated.

Tuttle, M. E.↗
DOE OSTI2021

Optimization of Magnesium-Doped Lithium Metal Anode for High Performance Lithium Metal Batteries through Modeling and Experiment

Lithium (Li)-magnesium (Mg) alloy with limited Mg amount, which can also be called Mg-doped Li (Li-Mg), has been considered as a potential alternative anode for high energy density rechargeable Li metal batteries. However, the optimum doping-content of Mg in Li-Mg anode and the mechanism of the improved performance are not well understood. In this study, density functional theory (DFT) calculations are used to investigate the effect of Mg amount in Li-Mg anode. The Li-Mg with about 5 wt. % Mg (abbreviated as Li-Mg5) has the lowest absorption energy of Li, thus all the surface area can be “controlled” by Mg atoms, leading to the smooth and continuous deposition of Li on the surface around the Mg center. A localized high concentration electrolyte enables Li-Mg5 to exhibit the best cycling stability in Li metal batteries with high-loading cathode and lean electrolyte under 4.4 V high-voltage, which is approaching the demand of practical application. This electrolyte also helps generate an inorganic-rich solid electrolyte interphase, which leads to smooth, compact and less corrosion layer on the Li-Mg5 surface. Both theoretical simulations and experimental results prove that Li-Mg5 has optimum Mg content and gives best battery cycling performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Efficient diffusion of superdense lithium via atomic channels for dendrite-free lithium–metal batteries

The non-uniform aggregation of fast-diffused Li on an anode surface would aggravate its tip-effect-induced nucleation/growth, leading to the notorious dendrite growth in Li metal batteries (LMBs). Tuning the Li diffusion on the anode surface has been regarded previously as a mainstream method to induce its uniform deposition, while the diffusion of Li in the anode bulk is usually ignored. In this study, conceptually different from the classic surface modification, we propose a molecular tunnelling strategy to construct atomic channels in graphite bulk, which enables the fast diffusion of superdense Li. Density functional theory calculations and ab initio molecular dynamics simulations prove that the bulk diffusion through atomic channels could become a new and dominating path. Its reversible and efficient diffusion has been further visualized by in situ transmission electron microscopy. As a result, when coupled with high-loading LiFePO 4 cathodes (20 mg cm –2 ), a high areal capacity and 100% capacity retention are achieved over 370 cycles. Through this work a new strategy is developed based on the bulk-diffusion of superdense Li for dendrite-free LMBs, which can be pervasive in other high-performance energy storage systems.

25 ENERGY STORAGE↗
NASA NTRS1984

Electrochemically Deposited Cadmium Electrode for Sealed Ni-cd Cells

An investigation into the work on electrochemical cadmium deposition processes is describred. A beaker impregnation system is constructed to investigate the practical limits of loading and the effect of various process parameters. Reasonably high loadings of cadmium are obtained and the process appears amenable to tight control and the production of uniform consistent electrodes. A pilot impregnation facility is built to further investigate electrodeposition processes. Both the inert anode and consummable anode processes are investigated. Results of this evaluation and an analysis of associated problems are presented.

Houston, W. H.↗
NASA NTRS1983

Energy efficient engine high-pressure turbine component rig performance test report

A rig test of the cooled high-pressure turbine component for the Energy Efficient Engine was successfully completed. The principal objective of this test was to substantiate the turbine design point performance as well as determine off-design performance with the interaction of the secondary flow system. The measured efficiency of the cooled turbine component was 88.5 percent, which surpassed the rig design goal of 86.5 percent. The secondary flow system in the turbine performed according to the design intent. Characterization studies showed that secondary flow system performance is insensitive to flow and pressure variations. Overall, this test has demonstrated that a highly-loaded, transonic, single-stage turbine can achieve a high level of operating efficiency.

Leach, K. P.↗