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At least 1,351 records · Page 75

High-Fidelity Computational Methodology for Stitched Composite Aerospace Structures

Due to the high demands for energy efficient commercial transportation, the aviation industry has taken a leading role in the integration of composite structures. Among the leading concepts to develop lighter, more fuel-efficient commercial transport is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, an enabling technology for hybrid wing bodies. Many proof-of-concept tests have been performed to demonstrate that the use of PRSEUS has improved the residual strength of damaged structures compared to conventional composite structures, but efficient computational tools must be developed before the concept can be commercially certified and implemented. In an attempt to address the need for efficient computational tools, a comprehensive modeling approach is developed and applied to investigate applications of PRSEUS at multiple scales. Therefore, a computational methodology has been progressively developed based on physically realistic concepts. The focus of the work described herein is to define the modeling characteristics required to accurately simulate the damage progression and failure of PRSEUS at the coupon scale. The work herein is focused on the development and analysis of a PRSEUS stringer, the methodology for which may be extended to other PRSEUS coupons and components.

Brandon Horton↗

MODELING AND TESTING OF A NOVEL ULTRA-LOW TEMPERATURE SCO2 OPPOSING PISTON EXPANDER

The Flameless Pressurized Oxy-Combustion (FPO) cycle, a novel flexible fuel technology, is being developed into a large pilot. This effort seeks to complete the preliminary engineering and planning of a 25 MWth Pilot Plant that will demonstrate the technology for scale-up to a commercial unit. The technology, pioneered by ITEA at the 5 MWth scale, must be brought to a higher technology readiness level (TRL) to be viable at the commercial scale. The 25 MWth pilot cycle was optimized for cost and technology development and demonstration. Preliminary drawings, layouts, and plans were defined. Process flow diagrams were used to describe the pilot configuration in greater detail. A heat and mass balance with stream data was created. A master equipment list specified the operating conditions for major pieces of equipment within the pilot using this heat and mass balance. The 25 MWth FPO pilot is assessed for environmental performance. A test campaign is developed to assess the type of test and number of hours required for pilot demonstration. The environmental performance is compared against projected performance at the commercial scale. This project builds upon extensive evaluation of the techno-economic performance of the FPO technology already performed by ITEA. This includes system improvements, such as the addition of a turbo-expander to the flue gas stream. Some of the performance-enhancing components are not as well defined as others. The primary goal of this effort was to bring all of the core cycle components to the same level of design maturity. A techno-economic assessment (TEA) evaluated the FPO technology at the commercial scale in comparison to the NETL baseline cases. The reference plants were used in combination with proprietary equipment estimates to build a plant capital cost and cost of electricity evaluation. FPO performed better than the sub-bituminous post-combustion capture cases. Further preliminary estimates of improvements to the FPO cycle show even further gains when compared to conventional carbon capture methods.

01 COAL, LIGNITE, AND PEAT↗

Additive manufacturing: a challenge to nuclear nonproliferation

Additive manufacturing (AM) is a rapidly developing technology that allows industries to automate and simplify the production of highly complicated items. Recently, there are concerns that AM techniques have the potential to be utilized in the fields of nuclear weapons and nuclear enrichment technology. Presently, there are very few international or domestic export controls that apply to AM's role in the nuclear industry, constituting an unmanaged proliferation pathway. Pre-existing export controls focus on general concepts and processes and do not consider specific nuances of various techniques that are categorized as additive manufacturing. To introduce legislation and controls that will be effective in monitoring proliferation pathways, one must investigate and characterize AM techniques and their nuclear applications. This paper categorizes and ranks 33 AM techniques based on their potential impact on the nuclear fuel cycle and the development of nuclear weapons. Through this method of characterization and categorization, export controls would address specific AM nuclear proliferation risks without disrupting the entire industry and fuel cycle. Additionally, legislation employing this method would identify loopholes in export controls using a holistic approach to managing and monitoring proliferation pathways.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Accelerating Sustainable Aviation Fuel Technology From Laboratory to Deployment: An Overview of NREL's Sustainable Aviation Fuel Pathways

The National Renewable Energy Laboratory (NREL) develops and de-risks a portfolio of technologies for converting renewable carbon resources into sustainable fuels, including sustainable aviation fuel (SAF). NREL works with industry, academia, and other national laboratories to develop, scale, and de-risk technology pathways for producing SAF from renewable resources such as biomass and other forms of waste carbon, including carbon dioxide.

BIOMASS FUELS↗

Marine Hydrogen Demonstration

This report summarizes Phase 1 of a project involving the design of a Floating Hydrogen Production and Dispensing Barge destined for the Port of San Francisco (SF). The H 2 Barge is designed to produce renewable H 2 at the rate of ~ 530 kg/day, storing 512 kg of hydrogen at 517-bar, allowing fast refueling of hydrogen fuel cell vessels and land-side hydrogen delivery trailers for distribution into the nascent SF hydrogen ecosystem. The broader considerations that impacted the H2 Barge design are also described. An account is given of a new review process formulated by the United States Coast Guard (USCG) to review this first-of-its-kind maritime implementation of hydrogen technology. The immediate goals of the H 2 Barge Project are to 1) demonstrate the feasibility, viability and methods of hydrogen production, storage and fueling in a maritime context, 2) help shape (where needed) and navigate the required local, state and federal regulatory gauntlet and 3) catalyze a “green hydrogen ecosystem” (both marine and landside) with locally produced renewable hydrogen at the San Francisco waterfront. A summary is also given of the modeling and experimental activity of Phase 1 directed to the development of science-based refueling protocols for large marine Type IV 250-bar hydrogen tanks. Combined modeling and experimental studies are reported of the filling of large (28 kg) 250-bar Type IV hydrogen tanks of the type being deployed on early hydrogen ferries, such as the MV Sea Change. The primary question was to determine how such tanks can be successfully filled (state of charge greater than 97%) within 45 minutes without exceeding the 82 °C temperature limit historically set for such tanks. The studies show that a gas injector is needed avoid thermal stratification during filling which can result in potential hot spots. Pre-cooling of the hydrogen was found to be essential in most cases, as ambient conditions greatly affect the need for a pre-cooling to achieve the 45-minute fill time. Pre-cooling cannot be supplied by nearby water, such as that found in nature (bays, lakes, rivers, etc.) because pre-cooling cooling below 0 °C was found to be necessary to avoid excessive compression heating. The experimental results afforded a calibration of the engineering model (SOFIL) for these large 250-bar tanks, which now enables using SOFIL to predict volume-averaged hydrogen filling temperatures to an accuracy of +/- 2.7°C for these tanks. The model can therefore be used to evaluate potential scenarios for development of a standardized fueling methodology for ferries utilizing large Type-IV tanks of the type examined here.

08 HYDROGEN↗

The Development and Implementation of the Kennedy Space Center Umbilical Clearance Tool

In preparation for NASAs upcoming Space Launch System program, the Kennedy Space Center is currently developing subsystems to provide fuel, purges and communications to the flight vehicle, known as umbilicals. It is vital to the crew and mission that these umbilicals release at T-0 without re-contacting the vehicle as it is accelerating from the launch pad. To help ensure this requirement is met by the program, a methodology of evaluating the moving bodies was developed and implemented into a tool using MATLAB. The tool, known as the KSC Umbilical Clearance Tool, takes a given elevation of interest and an umbilical retract profile within the plane to evaluate the clearance between the umbilical arm and thousands of independent flight vehicle drift profiles from a Monte Carlo analysis. The presentation will delve into the challenges associated with developing and implementing the tool framed in the context of evaluating the clearance for one of the SLS umbilicals.

Clearance↗

The Enhanced Injection and Mixing Project at NASA Langley

An overview of a research project aimed at enhancing fuel injection and mixing for scramjet engines at flight Mach numbers greater than 8 is presented. The specific objectives of this project are to increase knowledge and understanding of the fundamental physics governing scramjet fuel-air mixing, to develop strategies for improving injector performance and to develop functional relationships between mixing efficiency, losses due to mixing (such as total pressure loss, drag) and combustor/mixing length. The research approach consists of a closely coupled experimental and computational effort with experiments intended for exploring injection concepts and for anchoring computational fluid dynamics (CFD) simulations. The experiments are being conducted in the NASA Langley Arc-Heated Scramjet Test Facility and consist of helium injection into a Mach 6 air stream. Measurements include in-stream helium mole fraction, Pitot pressure, and total temperature as well as wall pressures and temperatures. Additionally, nitric oxide planar laser-induced fluorescence (NO PLIF) imaging will be used for flow visualization of the fuel plume. The numerical simulations, performed with the VULCAN CFD code, provide flowfield details unobtainable from the experiment. The current paper describes the experimental apparatus and diagnostic systems which have been developed and/or tested in preparation for the mixing tests and discusses numerical simulations performed to reduce the risk associated with the experimental design.

K F Cabell↗

Energy Impact of Connected and Automated Vehicle Technologies. Final report

The overarching goal of this project is to understand the potential impact of connected and automated vehicles. The goal was achieved through data collection, model development, algorithm designs, simulations, and limited field tests. The main outcomes from this project include: (1) we collected energy consumption and GPS data from 500 vehicles over one year, with a total mileage of 8 million miles; (2) Based on the collected data and other datasets collected at the University of Michigan, we developed a calibrated Ann Arbor model in Polaris (model developed by ANL), and the fuel economy accuracy was found to be around 3.9% by comparison with field collected data; (3) An open-source SUMO model of Ann Arbor was developed; (4) Eco-Routing algorithms in Ann Arbor using the SUMO model shows 6% fuel saving potential; (5) Experiments conducted at the Mcity test facility shows that human drivers roughly follow the Eco-driving suggestions roughly 70% of the time; (6) Based in the Ann Arbor travel patterns, we found that each shared automated vehicle can replace around 4 individually owned vehicles; and (7) Adaptive Traffic Signal Control Algorithm developed through this project has been validated both in simulations and preliminary test results. For connected and automated vehicles, on average the performance is 13% delay reduction, and 10% fuel reduction. While connected and automated vehicles are in their early stage of deployment, the results from this project confirm that there is significant potential for energy saving if the technologies are developed and used properly. The three main technologies studied in this project include eco-routing, shared autonomous rides, and adaptive traffic signal controls. The data collected and model developed through the project can be used to study many other connected and automated vehicle technologies.

02 PETROLEUM↗

Electrochemical conversion of coal-derived CO 2 into fuels and chemicals using a modified PEM electrolyzer. Final report

Opus 12 is developing an electrochemical process to convert CO 2 into chemicals and fuels. Using only CO 2 , water, and electricity as inputs, the electrochemical reduction of CO 2 could form the basis of an artificial carbon cycle that replaces a wide range of products that are currently derived from fossil fuel resources. We have developed a prototype that demonstrates high selectivity and current density for CO 2 conversion to CO, which can be used to make high-value products including methanol, acetic acid, polymers, and pharmaceuticals.

01 COAL, LIGNITE, AND PEAT↗

Skylab attitude control and angular momentum desaturation with one double-gimbaled control moment gyro

In case two control moment gyros fail, attitude control of Skylab can be maintained with the thruster attitude control system. This results, however, in a severely increased fuel consumption, depleting the fuel in a few days. Therefore, an alternate concept was developed which does not have large fuel consumption under any circumstances. In this concept the attitude reference is commanded to oscillate in the orbital plane with twice the orbital frequency and the remaining control moment gyro controls about orbital north and about the minimum moment-of-inertia axis, while the thruster attitude control system controls rate only about the remaining axis. This rate control in conjunction with the restoring torque due to the gravity gradient will keep bounded the excursion of the minimum moment-of-inertia axis out of the orbital plane. This alternate concept has the additional advantage that it needs no information on the principal moment-of-inertia axes misalignment and is completely insensitive to star tracker failure. Proper phasing of the attitude reference oscillation even allows angular momentum desaturation, which is responsible for the insensitivity of the thruster fuel consumption to unknown disturbances, like vent torques and magnetic torques.

Kennel, H. F.↗

The Direct Methanol Liquid-Feed Fuel Cell

Until the early 1990's the idea of a practical direct methanol fuel cell from transportation and other applications was just that, an idea. Several types of fuel cells that operate under near ambient conditions were under development.

Methanol Fuel Cell↗

Electrifying Aircraft Propulsion: Thermal Issues of Megawatt Scale Power Dense Electric Machines and Material Solutions

Aircraft are the last major mode of transportation to undergo electrification for many reasons, where the underlying reason is the sensitivity of aircraft performance to mass. This sensitivity demands that efficient, megawatt (MW)-scale high specific power density powertrains be developed to impact regional, single aisle and larger aircraft that account for the majority of fuel burn in commercial aviation. Developing MW-scale high specific power electric powertrains (machines, cables/busbars and power electronics) remains a significant challenge. While advanced power semiconductors have enabled higher voltages, densities, and operational frequencies this also leads to passing high current through smaller volumes when considering electric machines and power electronics. This poses significant thermal challenges. This is particularly true for electric machines that strive to surpass 13 kW/kg, which studies have shown to be desirable for electric aircraft propulsion. The necessity of handling high current densities to achieve MW power levels dictates that greater than 10kW of waste heat will be generated. Moreover, most of the heat is generated in the stator winding which is a mixture of electrical conductor (copper or aluminum), potting material, magnet wire (electrical) insulation and high voltage electrical insulation. Although the electrical conductor is a fantastic thermal conductor, it is also the source of the heat (carrying the electrical current) and is thermally isolated by the other materials. Simply letting the machine run at increased temperatures is an attractive idea, however the reality is that most of the suitable electric insulations and potting material candidates are not likely to satisfactorily operate at higher temperatures with reasonable life expectancies. The likelihood of developing new polymers that can satisfy the necessary functions (mechanical and electrical), operate at higher temperatures with acceptable lifetime in the near term is small. This has led the researchers at the NASA Glenn Research Center to examine electrically insulative materials in high power destiny electric machines, their thermal environment, and what solutions are realistic from a materials point of view. This presentation will touch on both the thermal challenges of electric machines and NASA Glenn’s research into material solutions.

Electric Aircraft Propulsion↗

Short Communication: Observation of Initial Burst Release of Fission Gas from High-Burnup UO 2 Nuclear Fuel During Thermal Transient

A system was developed and tested to provide a deeper understanding of the fission gas release kinetics from nuclear fuel during thermal transients. Pressure, temperature, spectral data, and optical images were simultaneously collected during resistive sample heating, and all released gases were collected in liquid nitrogen-cooled charcoal traps. Standup testing was performed with a high-burnup nuclear fuel segment from rod section with an average local burnup of 77 GWd/tU. During heating, the segment released approximately 6 ± 2% of generated fission gas inventory after ramp heating to 460°C. Here, heating ceased when the sample ejected from the holder, as observed by constant imaging.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Compare Mechanistic Predictions for Doped UO 2 Mechanical Response and Other Properties with Empirical Models and Experimental Measurements

The U.S. Department of Energy’s Nuclear Energy Advanced Modeling and Simulation program develops predictive capabilities using computational methods for the analysis and design of advanced reactor and fuel cycle systems. This program has been supporting the development of BISON, a high-fidelity, high resolution fuel performance tool at the engineering scale. As part of its development, additional modeling capabilities and improvements have been developed for relevant fuel forms. In this work, a fuel creep deformation model for Cr-doped fuel has been implemented into BISON, along with improvements to the empirical UO 2 fuel creep model based on experimental data and improvements to the radial power factor calculation for doped fuels. This work allows for more accurate simulation analyses for both UO 2 and doped-UO 2 fuels.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Alternative aircraft fuels

In connection with the anticipated impossibility to provide on a long-term basis liquid fuels derived from petroleum, an investigation has been conducted with the objective to assess the suitability of jet fuels made from oil shale and coal and to develop a data base which will allow optimization of future fuel characteristics, taking energy efficiency of manufacture and the tradeoffs in aircraft and engine design into account. The properties of future aviation fuels are examined and proposed solutions to problems of alternative fuels are discussed. Attention is given to the refining of jet fuel to current specifications, the control of fuel thermal stability, and combustor technology for use of broad specification fuels. The first solution is to continue to develop the necessary technology at the refinery to produce specification jet fuels regardless of the crude source.

Longwell, J. P.↗

Advanced Alkaline Membrane H 2 /Air Fuel Cell System with Novel Technique for Air CO 2 Removal

Over the course of this project, significant progress was achieved in developing the hydroxide exchange membrane fuel cell (HEMFC) and the electrochemically-driven CO₂ separator (EDCS), with a focus on improving performance, durability, and scalability. Key milestones were met, and the technology demonstrated potential for a wide range of applications, including fuel cell vehicles, direct air capture (DAC), and life support systems.

08 HYDROGEN↗

Measuring Critical Fuel Properties for Simulations to Accelerate Fuel Qualification

NREL's sustainable aviation fuel (SAF) research in the area of fuel properties and end use is focused on accelerating SAF development and deployment. This will be achieved by close collaboration with BETO program researchers on fuel property measurement and development of structure-property relationships. Additionally, fuel properties measured at often extreme engine operating conditions will be measured, and will be used as inputs to exascale ready simulations of aviation combustion turbines to reveal impacts of properties on turbine operation. This research will potentially lead to a widening of the allowable fuel property range for SAF, expanding SAF production process options and production volumes.

ADVANCED PROPULSION SYSTEMS↗

Wear Mechanism Analysis of a New Rotary Shear Biomass Comminution System

A new biomass comminution system, Crumbler rotary shear, was developed to process fuel-grade biomass. The rotary shear is more efficient than the traditional hammer mill in comminuting high-moisture biomass and producing more uniform particles with minimal fines. However, the milling unit experiences significant wear in processing dirty woodchips. This study investigated the wear mechanisms of the rotary shear system based on analysis of the minerals carried by woodchips and characterization of actual worn components. Abrasive wear was found to be the dominant effect, and localized adhesive wear (material transfer), microfracture (chipping), and plastic deformation were additional effects. Connections have been made between the wear progression of key cutting components and the particle size change of biomass extrinsic minerals. On the basis of the wear mechanism understanding, mitigations based on advanced tool materials and optimized tool geometric designs are being developed for improving the tool life and cutting efficiency.

09 BIOMASS FUELS↗