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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Band Edge Energetics of Heterostructured Nanorods: Photoemission Spectroscopy and Waveguide Spectroelectrochemistry of Au-Tipped CdSe Nanorod Monolayers

Conduction and valence band energies ( E CB , E VB ) for CdSe nanorods (NRs) functionalized with Au nanoparticle (NP) tips are reported here, referenced to the vacuum scale. We use (a) UV photoemission spectroscopy (UPS) to measure E VB for NR films, utilizing advanced approaches to secondary electron background correction, satellite removal to enhance spectral contrast, and correction for shifts in local vacuum levels; and (b) waveguide-based spectroelectrochemistry to measure E CB from onset potentials for electron injection into NR films tethered to ITO. For untipped CdSe NRs, both approaches show E VB = 5.9–6.1 eV and E CB = 4.1–4.3 eV. Addition of Au tips alters the NR band edge energies and introduces midgap states, in ways that are predicted to influence the efficiency of these nanomaterials as photoelectrocatalysts. UPS results show that Au tipping shifts E VB closer to vacuum by up to 0.4 eV, shifts the apparent Fermi energy toward the middle of the band gap, and introduces additional states above E VB . Spectroelectrochemical results determine these trends: Au tipping shifts E CB closer to vacuum, by 0.4–0.6 eV, and introduces midgap states below E CB , which are assigned as metal–semiconductor interface (MSI) states. Characterization of these band edge energies and understanding the origins of MSI states is needed to design energy conversion systems with proper band alignment between the light absorbing NR, the NP catalyst, and solution electron donors and acceptors. Furthermore, the complementary characterization protocols presented here should be applicable to a wide variety of thin films of heterogeneous photoactive nanomaterials, aiding in the identification of the most promising material combinations for photoelectrochemical energy conversion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1977

Space-Based Solar Power Conversion and Delivery Systems Study. Volume 1: Executive Summary

The research concerning space-based solar power conversion and delivery systems is summarized. The potential concepts for a photovoltaic satellite solar power system was studied with emphasis on ground output power levels of 5,000 MW and 10,000 MW. A power relay satellite, and certain aspects of the economics of these systems were also studied. A second study phase examined in greater depth the technical and economic aspects of satellite solar power systems. Throughout this study, the focus was on the economics of satellite solar power. The results indicate technical feasibility of the concept, and provide a preliminary economic justification for the first phase of a substantial development program. A development program containing test satellites is recommended. Also, development of alternative solar cell materials (other than silicon) is recommended.

Source record↗
DOE OSTI2011

NGNP Nuclear-Industrial Facility and Design Certification Boundaries White Paper

The Next Generation Nuclear Plant (NGNP) Project was initiated at Idaho National Laboratory by the U.S. Department of Energy pursuant to the 2005 Energy Policy Act and based on research and development activities supported by the Generation IV Nuclear Energy Systems Initiative. The principal objective of the NGNP Project is to support commercialization of the high temperature gas-cooled reactor (HTGR) technology. The HTGR is helium cooled and graphite moderated and can operate at reactor outlet temperatures much higher than those of conventional light water reactor (LWR) technologies. Accordingly, it can be applied in many industrial applications as a substitute for burning fossil fuels, such as natural gas, in addition to producing electricity, which is the principal application of current LWRs. These varied industrial applications may involve a standard HTGR modular design using different Energy Conversion Systems. Additionally, some of these process heat applications will require process heat delivery systems to lie partially outside the HTGR operator’s facility.

99 GENERAL AND MISCELLANEOUS↗
NASA NTRS1972

University role in astronaut life support systems: Space power supply systems

A brief description is given of the schemes suggested for providing electrical power aboard spacecraft. An attempt was made to list the major advantages and disadvantages of each scheme and to identify the particular areas in which it appears likely further research work may prove fruitful. Special attention was given to those research areas that appear suitable for colleges and university work. Chemical, solar, and nuclear power sources are considered together with the appropriate thermoelectric and turboelectric conversion systems.

Chin, L. Y.↗
DOE OSTI2025

Mechanical-Bond-Enabled Highly Efficient Charge Separation in a Light-Harvesting Hetero[2]Catenane

Photodriven charge separation is a key process for converting solar energy into chemical energy. However, it remains a challenge to develop artificial light-harvesting materials that can simultaneously achieve ultrafast charge separation and a long-lived charge-separated state with low energy loss. In contrast to conventional strategies based on covalent or noncovalent interactions, we employed a mechanical bond to forcibly assemble two strongly electron-deficient cationic chromophores (TTzBo x4+ and PDI-C 2+ ), which have very similar reduction potentials and exhibit limited noncovalent interactions, into a hetero[2]catenane (TTzPCat 6+ ). This design provides efficient π electronic couplings, enabling ultrafast charge separation (<2.3 ps) even with a low driving force (|ΔG CS | ≈ 160 meV). Furthermore, the adaptive molecular conformation of TTzPCat 6+ , in combination with the Marcus inverted region effect, successfully prolongs the charge-separated state lifetime (k CS /k CR > 1000), surpassing the conventional trade-off between driving force and charge separation efficiency in heterogeneous donor–acceptor systems. The photocatalytic system based on TTzPCat 6+ exhibits an over 2-fold enhancement in selective oxidation of aryl sulfides under mild conditions, demonstrating the potential of mechanical bonding for preparing photocatalytic materials. This investigation not only highlights a strategy for achieving highly efficient charge separation with low energy loss but also offers fresh insights into developing efficient solar energy conversion systems.

Charge transfer↗
NASA NTRS1979

A Conceptual Design Study on the Application of Liquid Metal Heat Transfer Technology to the Solar Thermal Power Plant

Alkali metal heat transfer technology was used in the development of conceptual designs for the transport and storage of sensible and latent heat thermal energy in distributed concentrator, solar Stirling power conversion systems at a power level of 15 kWe per unit. Both liquid metal pumped loop and heat pipe thermal transport were considered; system configurations included: (1) an integrated, focal mounted sodium heat pipe solar receiver (HPSR) with latent heat thermal energy storage; (2) a liquid sodium pumped loop with the latent heat storage, Stirling engine-generator, pump and valves located on the back side of the concentrator; and (3) similar pumped loops serving several concentrators with more centralized power conversion and storage. The focus mounted HPSR was most efficient, lightest and lowest in estimated cost. Design confirmation testing indicated satisfactory performance at all angles of inclination of the primary heat pipes to be used in the solar receiver.

Zimmerman, W. F.↗
NASA NTRS1988

Refractory metal alloys and composites for space power systems

Space power requirements for future NASA and other U.S. missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary source to meet these high levels of electrical demand. One way to achieve maximum efficiency is to operate the power supply, energy conversion system, and related components at relatively high temperatures. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide baseline information for space power systems in the 1900's and the 21st century. Basic research on the tensile and creep properties of fibers, matrices, and composites is discussed.

Stephens, Joseph R.↗
DOE OSTI2022

The role of lignin in the conversion of wheat straw to cellobionic acid by Neurospora crassa HL10

An engineered Neurospora crassa strain (HL10) naturally produces cellulases, cellobiose dehydrogenase (CDH), and heterologously expresses laccase. It can convert Avicel (cellulose) to cellobionic acid (cellobionate) without any enzyme addition at high yields. However, the addition of a catalytic amount of artificial redox mediators was required to achieve a high yield conversion. When a lignocellulosic substrate like wheat straw was used as the carbon source, it was found that adding exogenous artificial redox mediators did not improve cellobionate yield. We hypothesized that lignin and lignin degradation products were able to serve as redox mediators for the CDH-laccase conversion system. Experiments were designed to prove the hypothesis. When N. crassa HL10 was grown on Avicel, the addition of enzyme hydrolyzed lignin (EHL) can achieve a similar level of cellobionate production as with ABTS addition. The addition of EHL can increase the cellobionate production rate in the CDH-laccase bi-enzyme system using cellobiose as the substrate. The formation of lignin radicals, and the quenching of lignin radicals by reduced CDH, were verified by an electron paramagnetic resonance (EPR) experiment, providing further evidence that lignin radicals can serve as the electron acceptor of reduced CDH. Hence, lignocellulosic biomass is a self-sufficient substrate for the production of cellobionate. The conversion of the lignocellulosic substrate to cellobionate using N. crassa HL10 can be achieved without any exogenous enzyme addition or redox mediator addition.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Consensus International Solar Resource Standards and Best Practices Development

Standardization and best practices of data sets and models enable the industry to develop widely accepted protocols adapted to various stages of solar project development and operations. In collaboration with the International Energy Agency Photovoltaic Power Systems Programme Task 16, the National Renewable Energy Laboratory (NREL) developed and regularly updates the Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications. In collaboration with ASTM's radiometry subcommittee, NREL leads the development of various radiometric standards. These contribute to increased accuracy in the measurement of the solar resource available to conversion systems and boost the development and improvement of radiative models. These models can then provide the long-term geographic or climatic distribution of solar radiation for areas where measured solar data are not available. Further, these standards play a preeminent role in all aspects of solar energy projects, including standard conditions, methods and instrumentation, accelerated testing, and service lifetime of materials.

ASTM↗
DOE OSTI2014

Operations of a Radioisotope-based Propulsion System Enabling CubeSat Exploration of the Outer Planets

Exploration to the outer planets is an ongoing endeavor but in the current economical environment, cost reduction is the forefront of all concern. The success of small satellites such as CubeSats launched to Near-Earth Orbit has lead to examine their potential use to achieve cheaper science for deep space applications. However, to achieve lower cost missions; hardware, launch and operations costs must be minimized. Additionally, as we push towards smaller exploration beds with relative limited power sources, allowing for adequate communication back to Earth is imperative. Researchers at the Center for Space Nuclear Research are developing the potential of utilizing an advanced, radioisotope-based system. This system will be capable of providing both the propulsion power needed to reach the destination and the additional requirements needed to maintain communication while at location. Presented here are a basic trajectory analysis, communication link budget and concept of operations of a dual-mode (thermal and electric) radioisotope-based propulsion system, for a proposed mission to Enceladus (Saturnian icy moon) using a 6U CubeSat payload. The radioisotope system being proposed will be the integration of three sub-systems working together to achieve the overall mission. At the core of the system, stored thermal energy from radioisotope decay is transferred to a passing propellant to achieve high thrust – useful for quick orbital maneuvering. An auxiliary closed-loop Brayton cycle can be operated in parallel to the thrusting mode to provide short bursts of high power for high data-rate communications back to Earth. Additionally, a thermal photovoltaic (TPV) energy conversion system will use radiation heat losses from the core. This in turn can provide the electrical energy needed to utilize the efficiency of ion propulsion to achieve quick interplanetary transit times. The intelligent operation to handle all functions of this system under optimized conditions adds to the complexity of the mission architecture.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS1982

Overview of high-temperature materials for high-energy space power systems

The current state of technology and some of the more pressing research needs and challenges associated with the possible use of high temperature materials in future high energy space power systems are discussed. Particularly, emphasis is on the need to improve and quantify the fundamental understanding of the effects of the following: (1) fast neutron radiation on the properties and behavior of nuclear reactor fuels and claddings; and (2) long term, high temperature, space (vacuum) exposure on the properties of refractory metals considered for use as structural materials in various power conversion systems.

Saunders, N. T.↗
NASA NTRS2003

Overview of Non-nuclear Testing of the Safe, Affordable 30-kW Fission Engine, Including End-to-End Demonstrator Testing

Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. At the power levels under consideration (3-300 kW electric power), almost all technical issues are thermal or stress related and will not be strongly affected by the radiation environment. These issues can be resolved more thoroughly, less expensively, and in a more timely fashing with nonnuclear testing, provided it is prototypic of the system in question. This approach was used for the safe, affordable fission engine test article development program and accomplished viz cooperative efforts with Department of Energy labs, industry, universiites, and other NASA centers. This Technical Memorandum covers the analysis, testing, and data reduction of a 30-kW simulated reactor as well as an end-to-end demonstrator, including a power conversion system and an electric propulsion engine, the first of its kind in the United States.

VanDyke, M. K.↗
DOE OSTI2011

Coupling between gap plasmon polariton and magnetic polariton in a metallic-dielectric multilayer structure

The excitation of plasmons in a metallic nanostructure represents a feasible and practical approach for manipulating the propagation and absorption of light at the subwavelength scale. Of particular interest is the coupling between plasmons, which can be used to facilitate the spectral tunability and tailor the optical response of the structure. In this paper, we study the coupling between two highly localized plasmonic modes: gap plasmon polariton mode and magnetic polariton mode, supported by a metallic-dielectric multilayer structure. The strong coupling gives rise to the formation of hybrid plasmon modes and large mode splitting. These hybrid modes result in unique spectral-directional absorption characteristics in the structure. The findings hold promise in applications such as photonic and energy conversion systems as well as the design of plasmonic nanodevices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

A novel Doppler backscattering (DBS) system to simultaneously measure radio frequency plasma fluctuations and low frequency turbulence

A novel quadrature Doppler Backscattering (DBS) system has been developed and optimized for the E-band (60–90 GHz) frequency range using either O-mode or X-mode polarization in DIII-D plasmas. In general, DBS measures the amplitude of density fluctuations and their velocity in the lab frame. The system can simultaneously monitor both low-frequency turbulence (f < 10 MHz) and radiofrequency plasma density fluctuations over a selectable frequency range (20–500 MHz). Detection of high-frequency fluctuations has been demonstrated for low harmonics of the ion cyclotron frequency (e.g., 2f ci ~ 23 MHz) and externally driven high-frequency helicon waves (f = 476 MHz) using an adjustable frequency down conversion system. Importantly, this extends the application of DBS to a high-frequency spectral domain while maintaining important turbulence and flow measurement capabilities. This unique system has low phase noise, good temporal resolution (sub-millisecond), and excellent wavenumber coverage (k θ ~ 1–20 cm –1 and kr ≲ 30 cm –1 ). As a demonstration, localized internal DIII-D plasma measurements are presented from turbulence (f ≤ 5 MHz), Alfvenic waves (f ~ 6.5 MHz), ion cyclotron waves (f ≥ 20 MHz), as well as fluctuations around 476 MHz driven by an external high-power 476 MHz helicon wave antenna. In the future, helicon measurements will be used to validate GENRAY and AORSA modeling tools for prediction of helicon wave propagation, absorption, and current drive location for the newly installed helicon current drive system on DIII-D.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2011

Transient Response to Rapid Cooling of a Stainless Steel Sodium Heat Pipe

Compact fission power systems are under consideration for use in long duration space exploration missions. Power demands on the order of 500 W, to 5 kW, will be required for up to 15 years of continuous service. One such small reactor design consists of a fast spectrum reactor cooled with an array of in-core alkali metal heat pipes coupled to thermoelectric or Stirling power conversion systems. Heat pipes advantageous attributes include a simplistic design, lack of moving parts, and well understood behavior. Concerns over reactor transients induced by heat pipe instability as a function of extreme thermal transients require experimental investigations. One particular concern is rapid cooling of the heat pipe condenser that would propagate to cool the evaporator. Rapid cooling of the reactor core beyond acceptable design limits could possibly induce unintended reactor control issues. This paper discusses a series of experimental demonstrations where a heat pipe operating at near prototypic conditions experienced rapid cooling of the condenser. The condenser section of a stainless steel sodium heat pipe was enclosed within a heat exchanger. The heat pipe - heat exchanger assembly was housed within a vacuum chamber held at a pressure of 50 Torr of helium. The heat pipe was brought to steady state operating conditions using graphite resistance heaters then cooled by a high flow of gaseous nitrogen through the heat exchanger. Subsequent thermal transient behavior was characterized by performing an energy balance using temperature, pressure and flow rate data obtained throughout the tests. Results indicate the degree of temperature change that results from a rapid cooling scenario will not significantly influence thermal stability of an operating heat pipe, even under extreme condenser cooling conditions.

Mireles, Omar R.↗
DOE OSTI2020

Consensus International Solar Resource Standards and Best Practices Development: Preprint

Standardization and best practices of data sets and models enable the industry to develop widely accepted protocols for various stages of solar project development and operations. In collaboration with the International Energy Agency Photovoltaic Power Systems Programme Task 16, the National Renewable Energy Laboratory (NREL) developed and regularly updates the Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications. In collaboration with ASTM members on the radiometry subcommittee, NREL assists in and leads the development of radiometric standards that contribute to increased accuracy in the measurement of solar resources available to conversion systems and to the development and improvement of models. These models can then provide long-term geographic distribution of solar resources for areas where measured solar data are not available. Further, these standards play a preeminent role in all aspects of solar energy projects, including standard conditions, methods and instrumentation, accelerated testing, and service lifetime of materials.

41 EE - Solar Energy Technologies Office (EE-4S)↗
DOE OSTI2022

Value proposition of coatings or new alloys on hammer wear

The goal of this Case Study was to elucidate the value of improving of the life of parts that wear within a system in terms of the additional material cost that it takes to reach the level of improvement. We recognize that the failure limits and system performance are representative of a single system that may or may not exist in the real world, however, our goal of this project was not to provide an answer for a specific system or to provide a full understanding the economics of all potential systems. The analysis was performed using relative changes from the base alloy cost and considered relative improvements in part life in order to generalize the comparison without referencing specific alloys or coatings that might be employed. Ultimately, this work provides a first check of the potential for improving wear characteristics of grinder hammers to provide a meaningful and impactful benefit to biomass preprocessing and conversion systems. Key takeaways include: • Increasing the life of hammers by 3× provides a delivered feedstock cost benefit of approximately $\$2.25$/dry ton assuming that the relative cost of the hammer material of construction is not increased. • The feasible area of relative hammer cost increase ranges from 110% to 122% of the relative life increase, i.e., a 3× life increase can cost 3.66× the cost of the original hammers • Beyond a 3× increase in relative hammer life, little economic benefit is realized • Even when moisture impacts are included, the relationship between relative hammer cost and relative hammer life was reduced only slightly to a range of 108% to 116% • From the simulation we would expect delivered feedstock costs to be within ±$1.10/dry ton, based on the uncertainty analysis

09 BIOMASS FUELS↗
NASA NTRS1976

Mini-cavity plasma core reactors for dual-mode space nuclear power/propulsion systems

A mini-cavity plasma core reactor is investigated for potential use in a dual-mode space power and propulsion system. In the propulsive mode, hydrogen propellant is injected radially inward through the reactor solid regions and into the cavity. The propellant is heated by both solid driver fuel elements surrounding the cavity and uranium plasma before it is exhausted out the nozzle. The propellant only removes a fraction of the driver power, the remainder is transferred by a coolant fluid to a power conversion system, which incorporates a radiator for heat rejection. Neutronic feasibility of dual mode operation and smaller reactor sizes than those previously investigated are shown to be possible. A heat transfer analysis of one such reactor shows that the dual-mode concept is applicable when power generation mode thermal power levels are within the same order of magnitude as direct thrust mode thermal power levels.

Chow, S.↗