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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Reliable, High Power Density Inverters for Heavy Equipment Applications

With this final report, the combined team of the University of Arkansas (UA), University of Illinois, Urbana-Champaign (UIUC), Wolfspeed, Caterpillar, and Ampaire have successfully met all of their project objectives. Noteworthy for the heavy equipment portion of the project with Caterpillar is that the team made its project milestones two years into the project by designing a power dense motor drive for a permanent magnet synchronous machine. Upon finding out that Caterpillar had pivoted to switched-reluctance machines (SRMs), the team subsequently redesigned and implemented the SRM drive with a coolant temperature of 105°C! The other major task that the UA, UIUC, and Wolfspeed teams took on was the design of a PMSM drive for a hybrid aircraft that was flown on Feb. 20, 2023 by Ampaire after extensive testing and evaluation. While there were also technical objectives in thermal management, integrated gate drivers, reliability studies, and high temperature capacitors with integrated bussing, each of these have been fully reported on in quarterly reports. In brief, advances in thermal management and high temperature capacitors were utilized in order to achieve a 105°C motor drive. The integrated gate driver work resulted in a higher density drive with no loss of efficiency. Most of the last year, during a no-cost extension, was spent waiting for the Ampaire motor drive to be tested (outside of our project). Many months passed with the device just sitting in California while the company dealt with battery-related issues. This delayed the integration and testing activities until Fall 2022. Once those began, then the process took about 4-5 months to complete culminating in the test flight in Feb. 2023. By providing technical advances and integration into final platforms, the barrier to economic impact has been lowered. This project benefits the public by overcoming key technical barriers to electrified and hybrid electric heavy equipment and aircraft. This, in turn, leads to lower greenhouse gas emissions and a cleaner environment. This final report summarizes the integrated gate driver work and the Ampaire hybrid electric aircraft integration and test flight efforts. All other information has been previously reported in quarterly reports. A summary of the motor drives created during this project is provided along with a listing of publications.

42 ENGINEERING↗
NASA NTRS1990

High power density dc/dc converter: Selection of converter topology

The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

Divan, Deepakraj M.↗
DOE OSTI2025

Exploring the Use of Flexible Circuit Boards to the Increase Power Density of a Rotary Triboelectric Nanogenerator

EExpansion on previous triboelectric nanogenerator (TENG) research that investigated a freestanding rotary TENG. The previous prototype used a single printed circuit board (PCB) stator with exposed copper electrodes and an arcylic rotor with vinyl-cut fluorinated ethylene propylene (FEP) wedges. The second generation prototype again used a PCB stator but used a flexible PCB rotor consisting of alternating polyamide and copper wedges. This prototype was assembled in a stacked configuration, with the intent of increasing current output. Results indicated that the internal resistance of the prototype was decreased, allowing for higher current output. However, degradation of the power output was observed, which led to decay testing of the prototypes. To overcome charge decay, a self-exciting design is suggested as further work.

42 ENGINEERING↗
NASA NTRS2022

An Interim Assessment of High-Power-Density-Core Noise Levels

The aeroacoustic-noise implications associated with the small-core gas-turbine development effort underway in the NASA HyTEC Project are discussed. Due to the expected design choices, there are risks that the airport community noise, associated with landing and takeoff of civilian-transport aircraft, could be increased or, at minimum, that further overall propulsion-noise reduction could become limited. It is argued here that the main culprit in these scenarios is noise originating from sources in the combustor. The classical combustor-noise prediction model is summarized and its possible extension to the planned parameter space is discussed. An acoustic-power scaling law is derived and utilized to give initial estimates for what can be expected by core-design choices. An ideal-cycle parametric turbofan model provides input for these estimates.

aeroacoustics, turbomachinery noise, small-core no↗
DOE OSTI2025

High-emissivity, thermally robust emitters for high power density thermophotovoltaics

Thermal radiative energy transport is essential for high-temperature energy harvesting technologies, including thermophotovoltaics (TPVs) and grid-scale thermal energy storage. However, the inherently low emissivity of conventional high-temperature materials constrains radiative energy transfer, thereby limiting system performance and technoeconomic viability. Here, in this study, we demonstrate ultrafast femtosecond laser-material interactions to transform diverse materials into near-blackbody surfaces with broadband spectral emissivity above 0.96. This enhancement arises from hierarchically engineered light-trapping microstructures enriched with nanoscale features, effectively decoupling surface optical properties from bulk thermomechanical properties. These laser-blackened surfaces (LaBS) exhibit exceptional thermal stability, retaining high emissivity for over 100 h at temperatures exceeding 1,000°C, even in oxidizing environments. When applied as TPV thermal emitters, Ta LaBS double electrical power output from 2.19 to 4.10 W cm −2 at 2,200°C while sustaining TPV conversion efficiencies above 30%. This versatile, largely material-independent technique offers a scalable and economically viable pathway to enhance emissivity for advanced thermal energy applications.

laser-blackened surfaces↗
NASA NTRSDate not supplied

Thermally Conductive Insulation for High Power Density Electric Machines

In the mid 2000’s NASA challenged the aeronautics industry to identify the routes for achieving ambitious improvements in fuel burn, emission, and noise reductions. These so-called “N+3” studies were exploring broad changes three commercial aircraft generations, or nominally 30 years, in the future. Many intriguing propulsion-airframe integrated solutions were proposed and pursued, which incorporated technologies such as high-aspect-ratio wings, boundary-layer ingestion, and hybrid electric powertrains. This talk summarizes the approaches and achievements from the Hybrid Gas-Electric Propulsion Concept Technical Challenge that concluded in 2019. The balanced portfolio of concepts studies anchored with practical technology development demonstrated that electrified aircraft propulsion is an aircraft revolution whose time has come. Advanced materials will play a key role with enabling the increase in operating efficiencies and lifetime of these high power-dense electric machines. Progress made in materials development as part of NASA’s Advanced Air Transport Technology project will also be discussed.

electrical insulation↗
DOE OSTI2025

From the Discovery of the Giant Magnetocaloric Effect to the Development of High‐Power‐Density Systems

Caloric cooling and heating promise an efficient and reliable alternative to ubiquitous vapor-compression technology. In 1976, the very first near-room-temperature caloric system is developed, but it took another 20 years for this technology to fully bloom and gain global attention. The discovery of the giant magnetocaloric effect in Gd 5 Si 2 Ge 2 and the advance of the first long-operating magnetic refrigerator, both in 1997, due to the Ames National Laboratory and Astronautics Corporation of America cooperation, are two milestones that sparked ongoing interest in caloric research, which continues to thrive to this day. This review presents a brief history of caloric heat pumping, from the discovery of the magnetocaloric effect to the most recent developments in materials and systems. The contributions of Ames National Laboratory of the U.S. Department of Energy are highlighted, celebrating its 30-year anniversary in caloric research and paying tribute to two outstanding scientists, Vitalij K. Pecharsky and Karl A. Gschneidner, Jr., who inspired the caloric community for decades. The paper concludes with insights into remaining research and development challenges that must be addressed to enable the market transition of caloric technology and its widespread adoption.

caloric materials↗
DOE OSTI2023

Grooved electrodes for high-power-density fuel cells

Proton exchange membrane fuel cells (PEMFCs) are leading candidates to decarbonize the transport sector, but widespread deployment will require improvements in lifetime, fuel economy and cost. Here we present the grooved electrode, an alternative electrode structure that enhances PEMFC performance and durability by coupling high ionomer (ion-conducting binder) content for improved H + transport with grooves for rapid O 2 transport. Grooved electrodes provide up to 50% higher performance than state-of-the-art conventional electrodes under standard operating conditions. Fuel cell diagnostics combined with multiphysics modelling demonstrate that grooved electrodes provide facile O 2 transport despite their high ionomer content, enabling improved reaction rate uniformity. Grooved electrodes also provide improved durability, with less performance loss after carbon corrosion compared with baseline electrodes. Machine learning analysis demonstrates the potential to further optimize grooved structures for next-generation PEMFCs with enhanced performance and durability, enabling smaller and cheaper fuel cell stacks with higher fuel efficiency.

25 ENERGY STORAGE↗
DOE OSTI2024

Exploring mounting solutions for cryogenically cooled thin crystal optics in high power density x-ray free electron lasers

This study investigates three mounting methods—clamping, soldering, and a hybrid clamping–soldering approach—for cryogenically cooled thin diamond crystals crucial to stable operation of X-ray Free Electron Laser (XFEL) systems. While clamping methods exhibit temperature resilience and flexibility, meticulous design is required to prevent stress-induced warping and reduce thermal contact area. Soldering methods offer reliable mechanical and thermal bonding but encounter challenges due to the coefficient of thermal expansion mismatch at cryogenic temperatures. The hybrid method, integrating clamping and soldering with strain relief cuts, effectively mitigates overall distortion caused by mounting and XFEL thermal loads. These findings offer a novel mounting solution for high-performance x-ray optics in XFEL research and applications, ensuring stability and optimal functionality in cryogenic conditions.

Instruments & Instrumentation↗
DOE OSTI2022

The Role of Functionalized Conducting Polymer Binders in Improving Power Density and Cycle Life of Lithium-Sulfur Batteries

Lithium-Sulfur batteries are promising as the next-generation of low-cost, high-energy rechargeable batteries. However, the commercialization of this battery has been limited by poor rate capability and cycle life. To improve the performance of Li-S cells, we have investigated the role of two n-dopable conducting polymers, N2200 and N2200-OE, as binders for the sulfur cathode. The electron and ion transport properties of these polymer binders, along with their strong affinity for polysulfides, results in significantly enhanced performance compared to cells with the traditional insulating PVDF binder. The role of these conducting polymer binders in enhancing the performance of the cells is analyzed using impedance spectroscopy, shuttle current measurements, conductivity measurements, UV–vis spectroscopy, GIWAXS studies and post-cycling analysis of the anodes. The conducting polymer binders reduce the cell impedance by a factor of four leading to a marked improvement in rate capability. The shuttling of the polysulfides and the formation of insoluble sulfides at the anode is curtailed by the interaction of the polysulfides with the backbone of the polymer binders, leading to an impressive capacity retention of 82% after 500 cycles. These studies demonstrate the benefit of tailored polymer binders at the sulfur electrode in addressing the limitations of lithium-sulfur batteries.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Innovative Design and Manufacturing of 2.5D Battery with High Energy and Power Density (Final Report)

The goal of this project is to develop cathode inks, to be used in additive manufacturing (AM), that lead to a low-cost, fast manufacturing processes for a new type of non-planar, 2.5D lithium-ion battery (LIB). 2.5D batteries, comprised of a high-aspect-ratio 3D electrode combined with a 2D planar electrode, can simplify the fabrication process because there is no need for the alignment steps seen in traditional 3D batteries. For the success of the two AM processes identified in this project, development of cathode inks is key component because it allows for both platforms to be evaluated in achieving high performance batteries and ease of manufacturing. The two AM processes explored in this project are direct ink writing (DIW) and templating. Both of these processes have been shown to be successful in depositing materials for traditional LIBs and will be used now for the 3D array electrode configuration as part of the 2.5D battery.

25 ENERGY STORAGE↗
DOE OSTI2024

Rugged WBG Devices and Advanced Electric Machines for High Power Density Automotive Electric Vehicles

This work explored two very important approaches for supporting transportation electrification and reducing dependence on imports of critical materials. In the first task, several novel electric machine architectures with low rare earth metal content were compared analytically, then experimentally to verify their performance. Rare earth metals are imported largely from China and are widely used in many clean energy systems such as wind turbines and EV motors. Reducing our dependence on this critical material is an important objective for ensuring our independence and continued economic prosperity. In the second task, a GaN based inverter for EV inverters was developed to demonstrate the suitability of that wide bandgap semiconductor device in this important application.

42 ENGINEERING↗
NASA NTRS1981

High power densities from high-temperature materials interactions

Thermionic energy converters and metallic-fluid heat pipes are well suited to serve together synergistically. The two operating cycles appear as simple and isolated as their material problems seem forebodingly deceptive and complicated. Simplified equations verify material properties and interactions as primary influences on the operational effectiveness of both. Each experiences flow limitations in thermal emission and vaporization because of temperature restrictions redounding from thermophysicochemical stability considerations. Topics discussed include: (1) successful limitation of alkali-metal corrosion; (2) protection against external hot corrosive gases; (3) coping with external and internal vaporization; (4) controlling interfacial reactions and diffusion; and (5) meeting other thermophysical challenges; expansion matches and creep.

Morris, J. F.↗