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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 739 records · Page 41

Design considerations for future planetary space suits

Manned extravehicular activity (EVA) operations will be major mission elements of planned future U.S. space operations. Whether designed for orbital operations or planetary surface exploration, the EVA system must be safe and reliable, and must provide a high degree of performance capabilities. An extravehicular mobility unit (EMU) consisting of a space suit, EVA gloves, and a portable life support system (PLSS) is central to the EVA system. A rugged, highly reliable, mobile, reusable, and easily maintained EVA suit and compact PLSS must meet the specific requirements of the intended mission. Additional requirements imposed by exposure to surface and gravitational environments are the need for lightweight, high-strength materials for fabricating EMUs to prevent astronaut fatigue and the need for dust protection measures and removal techniques to prevent contamination. Also, operational pressure for habitats should be chosen so as to maintain zero-prebreathe conditions while allowing for lower EMU operating pressure.

Kosmo, Joseph J.↗

Value of Faster Computation for Power Grid Operation

As a result of the grid evolution meeting the information revolution, the power grid is becoming far more complex than it used to be. How to feed data in, perform analysis, and extract information in a real-time manner is a fundamental challenge in today’s power grid operation, not to mention the significantly increased complexity in the smart grid environment. Therefore, high performance computing (HPC) becomes one of the advanced technologies used to meet the requirement of real-time operation. This paper presents benefit case studies to show the value of fast computation for operation. Two fundamental operation functions, state estimation (SE) and contingency analysis (CA), are used as examples. In contrast with today’s tools, fast SE can estimate system status in a few seconds—comparable to measurement cycles. Fast CA can solve more contingencies in a shorter period, reducing the possibility of missing critical contingencies. The benefit case study results clearly show the value of faster computation for increasing the reliability and efficiency of power system operation.

high performance computing↗

Reliability model of a monopropellant auxiliary propulsion system

A mathematical model and associated computer code has been developed which computes the reliability of a monopropellant blowdown hydrazine spacecraft auxiliary propulsion system as a function of time. The propulsion system is used to adjust or modify the spacecraft orbit over an extended period of time. The multiple orbit corrections are the multiple objectives which the auxiliary propulsion system is designed to achieve. Thus the reliability model computes the probability of successfully accomplishing each of the desired orbit corrections. To accomplish this, the reliability model interfaces with a computer code that models the performance of a blowdown (unregulated) monopropellant auxiliary propulsion system. The computer code acts as a performance model and as such gives an accurate time history of the system operating parameters. The basic timing and status information is passed on to and utilized by the reliability model which establishes the probability of successfully accomplishing the orbit corrections.

Greenberg, J. S.↗

Model Predictive Control-based Optimal Coordination of Distributed Energy Resources

Distributed energy resources, such as renewable energy resources (wind, solar), energy storage and demand response, can be used to complement conventional generators. The uncertainty and variability due to high penetration of wind makes reliable system operations and controls challenging, especially in isolated systems. In this paper, an optimal control strategy is proposed to coordinate energy storage and diesel generators to maximize wind penetration while maintaining system economics and normal operation performance. The goals of the optimization problem are to minimize fuel costs and maximize the utilization of wind while considering equipment life of generators and energy storage. Model predictive control (MPC) is used to solve a look-ahead dispatch optimization problem and the performance is compared to an open loop look-ahead dispatch problem. Simulation studies are performed to demonstrate the efficacy of the closed loop MPC in compensating for uncertainties and variability caused in the system.

Mayhorn, Ebony T.↗

Saturn 5 Launch Vehicle Flight Evaluation Report, AS-510, Apollo 15 Mission

A postflight analysis of the Apollo 15 flight is presented. The performance of the launch vehicle, spacecraft, and lunar roving vehicle are discussed. The objective of the evaluation is to acquire, reduce, analyze, and report on flight data to the extent required to assure future mission success and vehicle reliability. Actual flight problems are identified, their causes are determined, and recommendations are made for corrective actions. Summaries of launch operations and spacecraft performance are included. Significant events for all phases of the flight are tabulated.

Source record↗

The implementation and use of Ada on distributed systems with high reliability requirements

The use and implementation of Ada were investigated in distributed environments in which reliability is the primary concern. In particular, the focus was on the possibility that a distributed system may be programmed entirely in Ada so that the individual tasks of the system are unconcerned with which processors are being executed, and that failures may occur in the software and underlying hardware. A secondary interest is in the performance of Ada systems and how that performance can be gauged reliably. Primary activities included: analysis of the original approach to recovery in distributed Ada programs using the Advanced Transport Operating System (ATOPS) example; review and assessment of the original approach which was found to be capable of improvement; development of a refined approach to recovery that was applied to the ATOPS example; and design and development of a performance assessment scheme for Ada programs based on a flexible user-driven benchmarking system.

Knight, J. C.↗

NFE-24-10417: Durability and Life-time Energy Performance Enhancement of Vapor Compression Systems

This project investigated the use of a Centrifugal Particle Separation (CPS) system to improve the durability and operational reliability of outdoor heat exchangers in vapor-compression based heating, ventilation, air conditioning, and refrigeration (HVACR) systems. The developed method introduced a novel dust and fouling mitigation approach by integrating an ambient air pre-cleaner that employs centrifugal forces to remove particulate matter from incoming air before it reaches the heat exchanger. By reducing the accumulation of dust and debris on coil surfaces, the CPS system aims to lower maintenance requirements and extend equipment lifespan. The project specifically involves coupling a centrifugal air pre-cleaner with a single-zone ductless mini-split system and evaluating its effectiveness in maintaining cleaner coil surfaces. Additionally, the study examined the impact of CPS integration on system energy performance. Through controlled experimental testing and performance monitoring, this work seeks to validate CPS-based air pre-cleaning as a practical, efficient solution for mitigating outdoor coil dust accumulation and fouling in both residential and commercial HVACR applications.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Health Monitoring Technology for Thermal Protection Systems on Reusable Hypersonic Vehicles

Integrated subsystem health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles (RLVs) in order to reduce life cycle costs, to increase safety margins, and to improve mission reliability. This talk summarizes a joint effort between NASA Ames and industry partners to develop rapid non-contact diagnostic tools for health and performance monitoring of thermal protection systems (TPS) on future RLVs. The specific goals for TPS health monitoring are to increase the speed and reliability of TPS inspections for improved operability at lower cost. The technology being developed includes a 3-D laser scanner for examining the exterior surface of the TPS, and a subsurface microsensor suite for monitoring the health and performance of the TPS. The sensor suite consists of passive overlimit sensors and sensors for continuous parameter monitoring in flight. The sensors are integrated with radio-frequency identification (RFID) microchips to enable wireless communication of-the sensor data to an external reader that may be a hand-held scanner or a large portal. Prototypes of the laser system and both types of subsurface sensors have been developed. The laser scanner was tested on Shuttle Orbiter Columbia and was able to dimension surface chips and holes on a variety of TPS materials. The temperature-overlimit microsensor has a diameter under 0.05 inch (suitable for placement in gaps between ceramic TPS tiles) and can withstand 700 F for 15 minutes.

Milos, Frank S.↗

Thermo-mechanical assessment of full SiC/SiC composite cladding for LWR applications with sensitivity analysis

SiC/SiC composites are considered among leading candidates for accident tolerant fuel cladding in light water reactors. However, when SiC-based materials are exposed to neutron irradiation, they experience significant changes in dimensions and physical properties. Under a large heat flux application (i.e. fuel cladding), the non-uniform changes in the dimensions and physical properties will lead to build-up of stresses in the structure over the course of time. To ensure reliable and safe operation of such a structure it is important to assess its thermo-mechanical performance under in-reactor conditions of irradiation and elevated temperature. In this work, the foundation for 3D thermo-mechanical analysis of SiC/SiC cladding is put in place and a set of analyses with simplified boundary conditions has been performed. The analyses were carried out with two different codes that were benchmarked against one another and prior results in the literature. A constitutive model is constructed and solved numerically to predict the stress distribution and variation in the cladding under normal operating conditions. The dependence of dimensions and physical properties variation with irradiation and temperature has been incorporated. These robust models may now be modified to take into account the axial and circumferential variation in neutron and heat flux to fully account for 3D effects. Here, the results from the simple analyses show the development of high tensile stresses especially in the circumferential and axial directions at the inner region of the cladding. Based on the results obtained, design guidelines are recommended. For lack of certainty in or tailor-ability for the physical and mechanical properties of SiC/SiC composite material a sensitivity analysis is conducted. The analysis results establish a precedence order of the properties based on the extent to which these properties influence the temperature and the stresses.

Accident tolerant fuel↗

Climate and water resource change impacts and adaptation potential for US power supply

Power plants that require cooling currently (2015) provide 85% of electricity generation in the United States. These facilities need large volumes of water and sufficiently cool temperatures for optimal operations, and projected climate conditions may lower their potential power output and affect reliability. We evaluate the performance of 1,080 thermoelectric plants across the contiguous US under future climates (2035-2064) and their collective performance at 19 North American Electric Reliability Corporation (NERC) sub-regions. Joint consideration of engineering interactions with climate, hydrology and environmental regulations reveals the region-specific performance of energy systems and the need for regional energy security and climate-water adaptation strategies. Despite climate-water constraints on individual plants, the current power supply infrastructure shows potential for adaptation to future climates by capitalizing on the size of regional power systems, grid configuration and improvements in thermal efficiencies. Without placing climate-water impacts on individual plants in a broader power systems context, vulnerability assessments that aim to support adaptation and resilience strategies misgauge the extent to which regional energy systems are vulnerable. As a result, climate-water impacts can lower thermoelectric reserve margins, a measure of systems-level reliability, highlighting the need to integrate climate-water constraints on thermoelectric power supply into energy planning, risk assessments, and system reliability management.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Versatile compact heater design for in situ nano-tomography by transmission X-ray microscopy

A versatile, compact heater designed at National Synchrotron Light Source-II for in situ X-ray nano-imaging in a full-field transmission X-ray microscope is presented. Heater design for nano-imaging is challenging, combining tight spatial constraints with stringent design requirements for the temperature range and stability. Finite-element modeling and analytical calculations were used to determine the heater design parameters. Performance tests demonstrated reliable and stable performance, including maintaining the exterior casing close to room temperature while the heater is operating at above 1100°C, a homogenous heating zone and small temperature fluctuations. Two scientific experiments are presented to demonstrate the heater capabilities: (i) in situ 3D nano-tomography including a study of metal dealloying in a liquid molten salt extreme environment, and (ii) a study of pore formation in icosahedral quasicrystals. The progression of structural changes in both studies were clearly resolved in 3D, showing that the new heater enables powerful capabilities to directly visualize and quantify 3D morphological evolution of materials under real conditions by X-ray nano-imaging at elevated temperature during synthesis, fabrication and operation processes. This heater design concept can be applied to other applications where a precise, compact heater design is required.

36 MATERIALS SCIENCE↗

Shipper/receiver difference verification of spent fuel by use of PDET

Spent fuel storage pools in most countries are rapidly approaching their design limits with the discharge of over 10,000 metric tons of heavy metal from global reactors. Countries like UK, France or Japan have adopted a closed fuel cycle by reprocessing spent fuel and recycling MOX fuel while many other countries opted for above ground interim dry storage for their spent fuel management strategy. Some countries like Finland and Sweden are already well on the way to setting up a conditioning plant and a deep geological repository for spent fuel. For all these situations, shipments of spent fuel are needed and the number of these shipments is expected to increase significantly. Although shipper/receiver difference (SRD) verification measurements are needed by IAEA when the recipient facility receives spent fuel, these are not being practiced to the level that IAEA has desired due to lack of a credible measurement methodology and instrument that can reliably perform these measurements to verify non-diversion of spent fuel during shipment and confirm facility operator declarations on the spent fuel. In this paper, we describe a new safeguards method and an associated instrument, Partial Defect Tester (PDET), which can detect pin diversion from Pressurized Water Reactor (PWR) Spent Fuel Assemblies in an in-situ condition. The PDET uses multiple tiny neutron and gamma detectors in the form of a cluster and a simple, yet highly precise, gravity-driven system to obtain underwater radiation measurements inside a Pressurized Water Reactor (PWR) spent fuel assembly. The method takes advantage of the PWR fuel design which contains multiple guide tubes which can be accessed from the top. The data obtained in such a manner can provide spatial distribution of neutron and gamma flux within a spent fuel assembly. Our simulation study as well as validation measurements indicated that the ratio of the gamma signal to the thermal neutron signal at each detector location normalized to the peak ratio of all the detector locations gives a unique signature that is sensitive to missing pins. The signature is principally dependent on the geometry of the detector locations, and little sensitive to enrichment or burn-up variations. A small variation in the fuel bundle, such as a few missing pins, changes the shape of the signature to enable detection. After verification of the non-diversion of spent fuel pins, the neutron signal and gamma signal are subsequently used to verify the consistency of the operator declaration on the fuel burn-up and cooling time. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Hardware Design of Medium Voltage SiC-Based Modular Multilevel Converters for Grid-Tied Applications

This paper presents a design of a 10 kV silicon carbide (SiC) MOSFET based modular multilevel converter (MMC). The MMC functions as the interconnection between a 24 kV dc bus and a 13. SkV distribution grid. This paper focuses on the hardware design of the MMC and its submodules. The gate driver, auxiliary power supply and bus bur in submodules are major components that need to meet high dv/dt immunity and high insulation voltage requirements. The gate driver achieves over 200 kV/us common mode transient immunity (CMTI). Its associated auxiliary power supply is based on an on-board transformer with over 30 kV insulation capability and 1.4 pF barrier capacitance. The busbar achieves less than 11 kV/cm electric field in the air to avoid partial discharges. Validation tests of the MMC submodule were performed by double pulse tests at 5 kV and buck converter tests at3 kV, 52A (peak). Reliable operations were achieved in validation tests.

auxiliary power supply↗

Distributed Sensor Coordination for Advanced Energy Systems

Motivation: The ability to collect key system level information is critical to the safe, efficient and reliable operation of advanced power systems. Recent advances in sensor technology have enabled some level of decision making directly at the sensor level. However, coordinating large numbers of sensors, particularly heterogeneous sensors, to achieve system level objectives such as predicting plant efficiency, reducing downtime or predicting outages requires sophisticated coordination algorithms. Indeed, a critical issue in such systems is how to ensure the interaction of a large number of heterogenous system components do not interfere with one another and lead to undesirable behavior. Objectives and Contributions: The long-term objective of this work is to provide sensor deployment, coordination and networking algorithms for large numbers of sensors to ensure the safe, reliable, and robust operation of advanced energy systems. Our two specific objectives are to: 1. Derive sensor performance metrics for heterogeneous sensor networks. 2. Demonstrate effectiveness, scalability and reconfigurability of heterogeneous sensor network in advanced power systems. The key technical contribution of this work is to push the coordination step to the design of the objective functions of the sensors, allowing networks of heterogeneous sensors to be controlled. By ensuring that the control and coordination is not specific to particular sensor hardware, this approach enables the design and operation of large heterogeneous sensor networks. In addition to the coordination coordination mechanism, this approach allows the system to be reconfigured in response to changing needs (e.g., sudden external events requiring new responses) or changing sensor network characteristics (e.g., sudden changes to plant condition). Impact: The impact of this work extends to a large class of problems relevant to the National Energy Technology Laboratory including sensor placement, heterogeneous sensor coordination, and sensor network control in advanced power systems. Each application has specific needs, but they all share the one crucial underlying problem: how to ensure that the interactions of a large number of heterogenous agents lead to coordinated system behavior. This proposal describes a new paradigm that addresses that very issue in a systematic way. Key Results and Findings: All milestones have been completed. Our results demonstrate that by properly shaping agent objective functions, we can develop large (up to 10,000 devices) heterogeneous sensor networks with key desirable properties. The first milestone shows that properly choosing agent-specific objective functions increases system performance by up to 99.9% compared to global evaluations. The second milestone shows evolutionary algorithms learn excellent sensor network coordination policies prior to network deployment, and these policies can be refined online once the network is deployed. The third milestone shows the resulting sensor networks networks are extremely robust to sensor noise, where networks with up to 25% sensor noise are capable of providing measurements with errors on the order of 10 -3 . The fourth milestone shows the resulting sensor networks are extremely robust to sensor failure, with 25% of the sensors in the system failing resulting in no significant performance losses after system reconfiguration.

42 ENGINEERING↗

Titanate Capacitors for Power Electronics

Titanium alloys were synthesized and coated with oxide dielectric films using anodizing in electrolytic baths. They possess high specific energies based on high charge-densities and high breakdown-electric-fields. These were made into alloy ribbons by rapid solidification by vacuum-spin casting, then anodized to form homogeneous dielectric films that serve as the medium in which electric charges are stored with high specific energy density in electrolytic capacitors. The new energy-dense dielectrics were formed by anodizing homogeneous Ti-Zr-X anode alloys, where X is a combination of Hf, Nb, Mo, Be, and/or Si. Thus homogeneous, dense and essentially-defect-free oxide-glass films were formed, e.g., (Ti-Zr-Hf-Be)O 2 films with high specific energy with stability over a wide voltage range, up to over 300 Volt, at temperatures from cryogenic to over 100 degrees C. When packaged with oxidizing electrolyte the dielectric is self-repairing in the event that accidental defects spring up. This provides reliable high-energy and high power performance with little de-rating, i.e., high reliability and lifetime in pulsed or high-frequency operating conditions.

25 ENERGY STORAGE↗

Electrical Energy Storage Data Submission Guidelines, Version 3

The knowledge of long-term health and reliability of energy storage systems is still unknown, yet these systems are proliferating and are expected increasingly to assist in the maintenance of grid reliability. Understanding long-term reliability and performance characteristics to the degree of knowledge similar to that of traditional utility assets requires operational data. This guideline is intended to inform numerous stakeholders on what data are needed for given functions, how to prescribe access to those data and the considerations impacting data architecture design, as well as provide these stakeholders insight into the data and data systems necessary to ensure storage can meet growing expectations in a safe and cost-efficient manner. Understanding data needs, the systems required, relevant standards, and user needs early in a project conception aids greatly in ensuring that a project ultimately performs to expectations.

25 ENERGY STORAGE↗

Probe measurements of a cesium plasma in a simulated thermionic energy converter

Cesium-filled thermionic energy converters are considered as electrical energy sources in future spacecraft requiring tens to hundreds of kilowatts of electric power. The high operating temperatures necessary for a large specific power and high efficiency impose stringent constraints on the converter fabrication. The converter physics for reducing operating temperatures and cesium plasma losses are being studied to achieve high reliability without sacrificing the power performance of the converters. Various cesium parameters which affect the converter performance are: (1) electron temperatures, (2) plasma ion densities, and (3) electric potential profiles. These were investigated using a Langmuir probe in a simulated converter. The parameters were measured in different cesium discharge modes.

Shimada, K.↗

Microprocessor control of a wind turbine generator

A microprocessor based system was used to control the unattended operation of a wind turbine generator. The turbine and its microcomputer system are fully described with special emphasis on the wide variety of tasks performed by the microprocessor for the safe and efficient operation of the turbine. The flexibility, cost and reliability of the microprocessor were major factors in its selection.

Gnecco, A. J.↗