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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

High-performance photonic transformers for DC voltage conversion

Abstract Direct current (DC) converters play an essential role in electronic circuits. Conventional high-efficiency DC voltage converters, especially step-up type, rely on switching operation, where energy is periodically stored within and released from inductors and/or capacitors connected in a variety of circuit topologies. Since these energy storage components, especially inductors, are fundamentally difficult to scale down, miniaturization of switching converters proves challenging. Furthermore, the resulting switching currents produce significant electromagnetic noise. To overcome the limitations of switching converters, photonic transformers, where voltage conversion is achieved through light emission and detection processes, have been demonstrated. However, the demonstrated efficiency is significantly below that of the switching converter. Here we perform a detailed balance analysis and show that with a monolithically integrated design that enables efficient photon transport, the photonic transformer can operate with a near-unity conversion efficiency and high voltage conversion ratio. We validate the theory with a transformer constructed with off-the-shelf discrete components. Our experiment showcases near noiseless operation and a voltage conversion ratio that is significantly higher than obtained in previous photonic transformers. Our findings point to the possibility of a high-performance optical solution to miniaturizing DC power converters and improving the electromagnetic compatibility and quality of electrical power.

42 ENGINEERING↗
DOE OSTI2021

Metastable Dion-Jacobson 2D structure enables efficient and stable perovskite solar cells

The performance of three-dimensional (3D) organic-inorganic halide perovskite solar cells (PSCs) can be enhanced through surface treatment with 2D layered perovskites that have efficient charge transport. We maximized hole transport across the layers of a metastable Dion-Jacobson (DJ) 2D perovskite that tuned the orientational arrangements of asymmetric bulky organic molecules. The reduced energy barrier for hole transport increased out-of-plane transport rates by a factor of 4 to 5, and the power conversion efficiency (PCE) for the 2D PSC was 4.9%. With the metastable DJ 2D surface layer, the PCE of three common 3D PSCs was enhanced by approximately 12 to 16% and could reach approximately 24.7%. For a triple-cation–mixed-halide PSC, 90% of the initial PCE was retained after 1000 hours of 1-sun operation at ~40°C in nitrogen.

14 SOLAR ENERGY↗
DOE OSTI2025

Energy-efficient multimodal mobility networks in transportation digital twins: Strategies and optimization

The study proposes a comprehensive Transportation Mobility (TransitMo) framework covering conceptual design, model formulation, optimization, simulation, and impact analysis of the transportation mobility system. TransitMo is composed of a transportation digital twin developed in Simulation of Urban MObility (SUMO) and an Intelligent Traffic Management and Control Center (ITMCC) that identifies the best ways to improve the movement of people within urban areas using various modes of transportation. This study encompasses advanced modeling techniques, algorithms, and strategic testing to optimize energy efficiency and mobility in a multimodal shared mobility network. TransitMo’s practical applications are exemplified through a city-scaled simulation network in Chattanooga, TN, employing demographic data to analyze historical traffic patterns and forecast future demands. Central to this methodology are three models: the User Preference Model (UP), the Energy Consumption Model (EC), and the System Optimization Model (SO). These models work in concert to iteratively devise the optimal travel incentives and minimize the total system cost in a real-time manner. In conclusion, test results verified that the proposed adaptive incentive program and optimized bus scheduling can improve network performance by increasing public transit ridership.

42 ENGINEERING↗
NASA NTRS1978

Short-haul CTOL aircraft research

The results of the reduced energy for commercial air transportation studies on air transportation energy efficiency improvement alternatives are reviewed along with subsequent design studies of advanced turboprop powered transport aircraft. The application of this research to short-haul transportation is discussed. The results of several recent turboprop aircraft design are included. The potential fuel savings and cost savings for advanced turboprop aircraft appear substantial, particularly at shorter ranges.

Williams, L. J.↗
DOE OSTI2026

Magnon confinement in epitaxial antiferromagnetic oxide heterostructures.

Magnons, the quanta of spin waves, have been extensively studied in a range of materials for spintronics, particularly for non-volatile logic-in-memory devices. Controlling magnons in conventional antiferromagnets and harnessing them in practical applications, however, remains a challenge. Here, we demonstrate highly efficient magnon transport in a LaFeO3/ BiFeO3/ LaFeO3 all-antiferromagnetic system, which can be controlled electrically, making it highly desirable for energy-efficient computation. Leveraging spin-orbit-driven spin-charge transduction, we demonstrate that this material architecture permits magnon confinement in ultrathin antiferromagnets, enhancing the output voltage generated by magnon transport by several orders of magnitude, which provides a pathway to enable magnetoelectric memory and logic functionalities. Additionally, the non-volatility of output voltage enables ultralowpower logic-in-memory processing, where magnonic devices can be efficiently reconfigured via electrically controlled magnon spin currents within magnetoelectric channels.

Husain, Sajid↗
DOE OSTI2022

Terpolymer Donor with Inside Alkyl Substituents on Thiophene π ‐Bridges toward Thiazolothiazole A 2 ‐Unit Enables 18.21% Efficiency of Polymer Solar Cells

Abstract PM6 is a widely used D–A copolymer donor in the polymer solar cells (PSCs). Incorporating second electron‐withdrawing (A 2 ) units into PM6 backbone by ternary D–A 1 –D–A 2 random copolymerization strategy is an effective approach to further improve its photovoltaic performance. Here, the authors synthesize the PM6‐based terpolymers by introducing thiazolothiazole as the A 2 units connecting with thiophene π‐bridges attaching alkyl substituent towards the A 2 unit (PMT‐CT) or towards D‐unit (PMT‐FT), and study the effect of the alkyl substituent position on the photovoltaic performance of them. Two terpolymers PMT‐FT‐10 and PMT‐CT‐10 are obtained by incorporating 10% A 2 units in the terpolymers. The film of PMT‐CT‐10 shows slightly up‐shifted highest occupied molecular orbital (HOMO) energy levels while better co‐planar structure than that of PMT‐FT‐10. Meanwhile, the PMT‐CT‐10:Y6 blend film exhibits better molecular packing properties, more proper phase separation and more balanced hole and electron mobilities, which are beneficial to more efficient exciton dissociation, efficient charge transport and weaker bimolecular recombination. Consequently, the PMT‐CT‐10 based PSCs obtain the highest power conversion efficiency of 18.21%. The results indicate that side chain position on the thiophene π‐bridges influence the device performance of the terpolymer donors, and PMT‐CT‐10 is a high efficiency polymer donor for the PSCs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2000

Magnetic Flux Compression Concept for Nuclear Pulse Propulsion and Power

The desire for fast, efficient interplanetary transport requires propulsion systems having short acceleration times and very high specific impulse attributes. Unfortunately, most highly efficient propulsion systems which are within the capabilities of present day technologies are either very heavy or yield very low impulse such that the acceleration time to final velocity is too long to be of lasting interest, One exception, the nuclear thermal thruster, could achieve the desired acceleration but it would require inordinately large mass ratios to reach the range of desired final velocities. An alternative approach, among several competing concepts that are beyond our modern technical capabilities, is a pulsed thermonuclear device utilizing microfusion detonations. In this paper, we examine the feasibility of an innovative magnetic flux compression concept for utilizing microfusion detonations, assuming that such low yield nuclear bursts can be realized in practice. In this concept, a magnetic field is compressed between an expanding detonation driven diamagnetic plasma and a stationary structure formed from a high temperature superconductor (HTSC). In general, we are interested in accomplishing two important functions: (1) collimation of a hot diamagnetic plasma for direct thrust production; and (2) pulse power generation for dense plasma ignition. For the purposes of this research, it is assumed that rnicrofusion detonation technology may become available within a few decades, and that this approach could capitalize on recent advances in inertial confinement fusion ICF) technologies including magnetized target concepts and antimatter initiated nuclear detonations. The charged particle expansion velocity in these detonations can be on the order of 10 (exp 6)- 10 (exp 7) meters per second, and, if effectively collimated by a magnetic nozzle, can yield the Isp and the acceleration levels needed for practical interplanetary spaceflight. The ability to ignite pure fusion micro-bursts with reasonable levels of input energy is an equally challenging scientific problem. It remains to be seen, however, whether an effective ignition driver can be developed which meets the requirements for practical spaceflight application (namely high power density, compactness, low weight, and low cost). In this paper, system level performance and design issues are examined including generator performance, magnetic flux compression processes, magnetic diffusion processes, high temperature superconductor (HTSC) material properties, plasmadynamic processes, detonation plasma expansion processes, magnetohydrodynamic instabilities, magnetic nozzle performance, and thrust production performance. Representative generator performance calculations based on a simplified skin layer formulation are presented as well as the results of exploratory small-scale laboratory experiments on magnetic flux diffusion in HTSC materials. In addition, planned follow-on scientific feasibility experiments are described which utilize high explosive detonations and high energy gas discharges to simulate the plasma conditions associated with thermonuclear micro-detonations.

Litchford, Ronald J.↗
NASA NTRS1977

User access to the National Space Transportation System

Economical and efficient use of the Space Transportation System (STS) will depend to a large extent on the ability to utilize standard procedures and operations; and for early users transitioning from expendable launch vehicles, the ability to use previous procedures and documentation. Users of the STS will need to know how and where to obtain the information needed to know the STS capabilities, how to obtain a flight assignment, costs involved, and processing of their payloads in preparation for launch.

Mccoy, H. E.↗
NASA NTRS1991

The civil tiltrotor aircraft's potential in developing economies

The civilian tiltrotor (CTR) is analyzed as a new transportation technology with the potential for changing one of the key economic factors linked to Third World economic development. It is contended that efficient, low-cost transport services are a necessary condition for the economic development of Third World countries and that the CTR's capabilities and operating costs can provide more efficient transport services than have heretofore been available to such countries. A case study of potential CTR use among the nations of the Carribean Basin region appears to offer both analytical and empirical support to these contentions. The analysis indicates that normal market mechanisms are adequate for development of air cargo services using the CTR's capabilities. It is suggested that implementation of this service may require new institutional arrangements, but overall it is concluded that tiltrotor technology could make an important contribution to the economic development of Third World countries.

Alton, Larry R.↗
NASA NTRS1978

Fuel conservative aircraft engine technology

NASA's Aircraft Energy Efficiency Program, initiated in an effort to minimize the adverse impact of the worldwide fuel crisis, will develop technology for more fuel-efficient subsonic transport aircraft. The program includes three major propulsion projects: (1) Engine Component Improvement, directed at current engines, (2) Energy Efficient Engine, directed at new turbofan engines, and (3) Advanced Turboprops, directed at technology for advanced turboprop-powered aircraft. The present paper reviews the current status of each of these projects and describes some of the technologies and recent accomplishments.

Nored, D. L.↗
NASA NTRS1978

Fuel conservative aircraft engine technology

Technology developments for more fuel-efficiency subsonic transport aircraft are reported. Three major propulsion projects were considered: (1) engine component improvement - directed at current engines; (2) energy efficient engine - directed at new turbofan engines; and (3) advanced turboprops - directed at technology for advanced turboprop-powered aircraft. Each project is reviewed and some of the technologies and recent accomplishments are described.

Nored, D. L.↗
NASA NTRS1989

Display-based communications for advanced transport aircraft

The next generation of civil transport aircraft will depend increasingly upon ground-air-ground and satellite data link for information critical to safe and efficient air transportation. Previous studies which examined the concept of display-based communications in addition to, or in lieu of, conventional voice transmissions are reviewed. A full-mission flight simulation comparing voice and display-based communication modes in an advanced transport aircraft is also described. The results indicate that a display-based mode of information transfer does not result in significantly increased aircrew workload, but does result in substantially increased message acknowledgment times when compared to conventional voice transmissions. User acceptance of the display-based communication system was generally high, replicating the findings of previous studies. However, most pilots tested expressed concern over the potential loss of information available from frequency monitoring which might result from the introduction of discrete address communications. Concern was expressed by some pilots for the reduced time available to search for conflicting traffic when using the communications display system. The implications of the findings for the design of display-based communications are discussed.

Lee, Alfred T.↗
NASA NTRS2019

The NASA Urban Air Mobility Testbed Flight Research Aircraft

The National Aeronautics and Space Administration (NASA) is leading government, industry and academic research effort known as Urban Air Mobility (UAM). The UAM activity goal is to develop the technology needed to make possible an urban air transportation system that makes use of human-crewed and crewless vehicles using automation, artificial intelligence and other technologies to safely and efficiently air transport people and goods within an urban environment. The NASA Langley Research Center (LaRC) created a UAM Flight Research Testbed Aircraft from a Cessna LC40 general aviation aircraft. The testbed has updated digital avionics and research systems needed to conduct flight research. The aircraft has two separate autopilots; a standard Federal Aviation Ad-ministration (FAA) certified system, and a modified research autopilot. The research autopilot has modifications that allow increased authority and enhancements to allow more automation and artificial intelligence controls. A network of three research computers hosts software to research several activities including automated air traffic sense and avoid, ground collision avoidance and obstacle avoidance. These UAM research activities involve automation and artificial intelligence technologies developed at three NASA centers. The NASA Langley, NASA Armstrong, and NASA Ames Research Centers are working together to develop and test these UAM technologies. This paper provides details of the systems, capabilities and research projects of the UAM Testbed Research Aircraft.

Howell, Charles T.↗
DOE OSTI2024

De Novo Design of Spiro-Type Hole-Transporting Material: Anisotropic Regulation Toward Efficient and Stable Perovskite Solar Cells

2,2',7,7'-Tetrakis(N,N-di-p-methoxyphenyl)-amine-9,9'-spirobifluorene (Spiro-OMeTAD) represents the state-of-the-art hole-transporting material (HTM) in n-i-p perovskite solar cells (PSCs). However, its susceptibility to stability issues has been a long-standing concern. In this study, we embark on a comprehensive exploration of the untapped potential within the family of spiro-type HTMs using an innovative anisotropic regulation strategy. Diverging from conventional approaches that can only modify spirobifluorene with single functional group, this approach allows us to independently tailor the two orthogonal components of the spiro-skeleton at the molecular level. The newly designed HTM, SF-MPA-MCz, features enhanced thermal stability, precise energy level alignment, superior film morphology, and optimized interfacial properties when compared to Spiro-OMeTAD, which contribute to a remarkable power conversion efficiency (PCE) of 24.53% for PSCs employing SF-MPA-MCz with substantially improved thermal stability and operational stability. Note that the optimal concentration for SF-MPA-MCz solution is only 30 mg/ml, significantly lower than Spiro-OMeTAD (>70 mg/ml), which could remarkably reduce the cost especially for large-area processing in future commercialization. This work presents a promising avenue for the versatile design of multifunctional HTMs, offering a blueprint for achieving efficient and stable PSCs.

14 SOLAR ENERGY↗
DOE OSTI2024

Vehicle and Mobility Technologies 2024 Annual Impact Report

Research and development at the National Renewable Energy Laboratory supports the U.S. Department of Energy's Vehicle Technologies Office in advancing efficient and sustainable transportation technologies that will improve energy efficiency, fuel economy, and mobility energy productivity, and will enable America to achieve a resilient, secure, clean, and affordable transportation future.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗