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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Monte Carlo Simulations of the Response of the MARIE Instrument

The MARIE instrument aboard Mars Odyssey functions as a telescope for the detection of charged, energetic, nuclei. The directionality that leads to the telescope description is achieved by requiring coincident signals in two designated detectors in MARIE s silicon detector stack for the instrument to trigger. Because of this, MARIE is actually a bi directional telescope. Triggering particles can enter the detector stack by passing through the lightly shielded front of the instrument, but can also enter the back of the instrument by passing through the bulk of Odyssey. Because of this, understanding how to relate the signals recorded by MARIE to astrophysically important quantities such as particle fluxes or spectra exterior to the spacecraft clearly requires detailed modeling of the physical interactions that occur as the particles pass through the spacecraft and the instrument itself. In order to facilitate in the calibration of the MARIE data, we have begun a program to simulate the response of MARIE using the FLUKA [1] [2] Monte Carlo radiation transport code.

Andersen, V.↗
NASA NTRS2010

Hollow Fiber Spacesuit Water Membrane Evaporator Development and Testing for Advanced Spacesuits

The spacesuit water membrane evaporator (SWME) is being developed to perform the thermal control function for advanced spacesuits to take advantage of recent advances in micropore membrane technology in providing a robust heat-rejection device that is potentially less sensitive to contamination than is the sublimator. Principles of a sheet membrane SWME design were demonstrated using a prototypic test article that was tested in a vacuum chamber at JSC in July 1999. The Membrana Celgard X50-215 microporous hollow fiber (HoFi) membrane was selected after recent contamination tests as the most suitable candidate among commercial alternatives for HoFi SWME prototype development. A design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype consisting 14,300 tube bundled into 30 stacks, each of which are formed into a chevron shape and separated by spacers and organized into three sectors of ten nested stacks. Vacuum chamber testing has been performed characterize heat rejection as a function of inlet water temperature and water vapor backpressure and to show contamination resistance to the constituents expected to be found in potable water produced by the distillation processes. Other tests showed the tolerance to freezing and suitability to reject heat in a Mars pressure environment.

Bue, Grant C.↗
NASA NTRS2013

Hollow-Fiber Spacesuit Water Membrane Evaporator

The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

Bue, Grant↗
DOE OSTI2020

3-dimensional x-ray imager

The invention utilizes one exposure without moving parts to provide multiple x-ray views of an object. It relies on a 3D detector, which can be a stack of film plates, and a specified focusing x-ray optic. The x-ray optic, discussed below, allows collection of x-rays from a localized volume, just like an ordinary optical lens, and the stacked film plate, or other 3D detector design, allows collection of the multiple focal plane information from one line of sight.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Characterization of Tunnel Oxides in TOPCon Solar Cells

The 1.12 nm thickness for the tunnel oxide layer is near the optimal range described by Choi et al. This thickness should be effective at enabling quantum tunneling; however, it is slightly lower than the reported optimal range which could negatively impact the passivation of the poly-Si interface. An appropriate balance between the two functions must be met to optimize efficiency. Follow up work could focus on testing the optimal range for tunnel oxide thickness in TOPCon solar cells, as well as improving the manufacturing process to produce better control of film thickness. This work could be extended into more advanced TOPCon solar cells including double or triple stack structures, as well as experimental pinhole designs.

SOLAR ENERGY↗
NASA NTRS1994

Performance model of a recirculating stack nickel hydrogen cell

A theoretical model of the nickel hydrogen battery cell has been utilized to describe the chemical and physical changes during charge and overcharge in a recirculating stack nickel hydrogen cell. In particular, the movement of gas and electrolyte have been examined as a function of the amount of electrolyte put into the cell stack during cell activation, and as a function of flooding in regions of the gas screen in this cell design. Additionally, a two-dimensional variation on this model has been utilized to describe the effects of non-uniform loading in the nickel-electrode on the movement of gas and electrolyte within the recirculating stack nickel hydrogen cell. The type of nonuniform loading that has been examined here is that associated with higher than average loading near the surface of the sintered nickel electrode, a condition present to some degree in many nickel electrodes made by electrochemical impregnation methods. The effects of high surface loading were examined primarily under conditions of overcharge, since the movement of gas and electrolyte in the overcharging condition was typically where the greatest effects of non-uniform loading were found. The results indicate that significant changes in the capillary forces between cell components occur as the percentage of free volume in the stack filled by electrolyte becomes very high. These changes create large gradients in gas-filled space and oxygen concentrations near the boundary between the separator and the hydrogen electrode when the electrolyte fill is much greater than about 95 percent of the stack free volume. At lower electrolyte fill levels, these gaseous and electrolyte gradients become less extreme, and shift through the separator towards the nickel electrode. Similarly, flooding of areas in the gas screen cause higher concentrations of oxygen gas to approach the platinum/hydrogen electrode that is opposite the back side of the nickel electrode. These results illustrate the need for appropriate pore size distributions, and the maintenance of both convective electrolyte and gas flow paths through the stack, if the recirculating stack nickel hydrogen cell design is to work properly.

Zimmerman, Albert H.↗
NASA NTRS1989

Design of nonpolarizing achromatic beamsplitters with dielectric multilayer coatings

A novel design approach is presented for nominally nonpolarizing beamsplitters with very low polarization over an extended wavelength range, with low angular sensitivity. A high degree of intensity matching for s and p polarization in a given wavelength interval, from 500 to 600 nm, has been obtained for multilayer stacks derived from an initial graded-index film design by matching of the characteristic matrices. This graded-index film design maintains a very low polarization ratio for almost the complete visible region, covering a wavelength range about twice that covered by the derived homogeneous multilayer stack.

Zukic, Muamer↗
NASA NTRS2003

Systems Analysis Initiated for All-Electric Aircraft Propulsion

A multidisciplinary effort is underway at the NASA Glenn Research Center to develop concepts for revolutionary, nontraditional fuel cell power and propulsion systems for aircraft applications. There is a growing interest in the use of fuel cells as a power source for electric propulsion as well as an auxiliary power unit to substantially reduce or eliminate environmentally harmful emissions. A systems analysis effort was initiated to assess potential concepts in an effort to identify those configurations with the highest payoff potential. Among the technologies under consideration are advanced proton exchange membrane (PEM) and solid oxide fuel cells, alternative fuels and fuel processing, and fuel storage. Prior to this effort, the majority of fuel cell analysis done at Glenn was done for space applications. Because of this, a new suite of models was developed. These models include the hydrogen-air PEM fuel cell; internal reforming solid oxide fuel cell; balance-of-plant components (compressor, humidifier, separator, and heat exchangers); compressed gas, cryogenic, and liquid fuel storage tanks; and gas turbine/generator models for hybrid system applications. Initial mass, volume, and performance estimates of a variety of PEM systems operating on hydrogen and reformate have been completed for a baseline general aviation aircraft. Solid oxide/turbine hybrid systems are being analyzed. In conjunction with the analysis efforts, a joint effort has been initiated with Glenn s Computer Services Division to integrate fuel cell stack and component models with the visualization environment that supports the GRUVE lab, Glenn s virtual reality facility. The objective of this work is to provide an environment to assist engineers in the integration of fuel cell propulsion systems into aircraft and provide a better understanding of the interaction between system components and the resulting effect on the overall design and performance of the aircraft. Initially, three-dimensional computer-aided design (CAD) models of representative PEM fuel cell stack and components were developed and integrated into the virtual reality environment along with an Excel-based model used to calculate fuel cell electrical performance on the basis of cell dimensions (see the figure). CAD models of a representative general aviation aircraft were also developed and added to the environment. With the use of special headgear, users will be able to virtually manipulate the fuel cell s physical characteristics and its placement within the aircraft while receiving information on the resultant fuel cell output power and performance. As the systems analysis effort progresses, we will add more component models to the GRUVE environment to help us more fully understand the effect of various system configurations on the aircraft.

Kohout, Lisa L.↗
NASA NTRS2010

Design of Reflective, Photonic Shields for Atmospheric Reentry

We present the design of one-dimensional photonic crystal structures, which can be used as omnidirectional reflecting shields against radiative heating of space vehicles entering the Earth's atmosphere. This radiation is approximated by two broad bands centered at visible and near-infrared energies. We applied two approaches to find structures with the best omnidirectional reflecting performance. The first approach is based on a band gap analysis and leads to structures composed of stacked Bragg mirrors. In the second approach, we optimize the structure using an evolutionary strategy. The suggested structures are compared with a simple design of two stacked Bragg mirrors. Choice of the constituent materials for the layers as well as the influence of interlayer diffusion at high temperatures are discussed.

Komarevskiy, Nikolay↗
NASA NTRS2008

Optical Navigation for the Orion Vehicle

The Orion vehicle is being designed to provide nominal crew transport to the lunar transportation stack in low Earth orbit, crew abort prior during transit to the moon, and crew return to Earth once lunar orbit is achieved. One of the design requirements levied on the Orion vehicle is the ability to return to the vehicle and crew to Earth in the case of loss of communications and command with the Mission Control Center. Central to fulfilling this requirement, is the ability of Orion to navigate autonomously. In low-Earth orbit, this may be solved with the use of GPS, but in cis-lunar and lunar orbit this requires optical navigation. This paper documents the preliminary analyses performed by members of the Orion Orbit GN&C System team.

Crain, Timothy↗
DOE OSTI2020

Busbar Design and Optimization for Voltage Overshoot Mitigation of a Silicon Carbide High-Power Three-Phase T-Type Inverter

The silicon carbide (SiC) devices have faster switching speed than that of the conventional silicon (Si) devices, which however may cause excessive device voltage overshoot. Larger gate resistance can help to restrain the overshoot, it however slows down the switching speed and increases switching losses. There are other methods that can mitigate the voltage overshoot, e.g., using low-inductance busbars, adding snubber circuits, etc. In this article, the busbar design for a 250-kW SiC three-level T-type inverter is investigated. The current commutation loops (CCLs) are first analyzed using a single-phase equivalent circuit. Then the detailed busbar design methods, especially a 3-D busbar design concept, are proposed to select the optimal stacking order for the multilayer laminated busbar and to address constraints posed by the physical terminal arrangements of SiC modules and dc-link capacitors. The stray inductance in each CCL is extracted via a finite element analysis and validated on the actual inverter busbar prototypes using an impedance analyzer. To further minimize the busbar stray inductance, a hybrid busbar structure with printed circuit board based buffer circuit using high-frequency decoupling capacitors is designed and evaluated in this article. Lastly, the effectiveness of the designed busbars as well as the buffer circuit are validated using experimental studies.

42 ENGINEERING↗
NASA NTRS2005

Tow-Steered Panels With Holes Subjected to Compression or Shear Loads

Tailoring composite laminates to vary the fiber orientations within a fiber layer of a laminate to address non-uniform stress states and provide structural advantages such as the alteration of principal load paths has potential application to future low-cost, light-weight structures for commercial transport aircraft. Evaluation of this approach requires the determination of the effectiveness of stiffness tailoring through the use of curvilinear fiber paths in flat panels including the reduction of stress concentrations around the holes and the increase in load carrying capability. Panels were designed through the use of an optimization code using a genetic algorithm and fabricated using a tow-steering approach. Manufacturing limitations, such as the radius of curvature of tows the machine could support, avoidance of wrinkling of fibers and minimization of gaps between fibers were considered in the design process. Variable stiffness tow-steered panels constructed with curvilinear fiber paths were fabricated so that the design methodology could be verified through experimentation. Finite element analysis where each element s stacking sequence was accurately defined is used to verify the behavior predicted based on the design code. Experiments on variable stiffness flat panels with central circular holes were conducted with the panels loaded in axial compression or shear. Tape and tow-steered panels are used to demonstrate the buckling, post-buckling and failure behavior of elastically tailored panels. The experimental results presented establish the buckling performance improvements attainable by elastic tailoring of composite laminates.

Jegley, Dawn C.↗
DOE OSTI2025

Cost analysis of alternative large-scale high-temperature solid oxide electrolysis hydrogen production facilities

We extend our past cost analysis of gigawatt-scale solid oxide electrolysis (SOE) facilities that produce high purity hydrogen gas from water by estimating construction and operating costs for three new alternative design cases: (1) offsite feed steam generation; (2) near-atmospheric pressure (NAP) stack; and (3) onsite electric boiler feed steam generation. Pressure effects on hydrogen electrode-(cathode-)supported SOE cell (SOEC) stack performance are estimated for the same assumed cell and stack construction and used to determine facility-wide stack capital costs for achieving a fixed H2 production at different pressures. Modular balance of plant (BOP) process equipment capital costs are estimated for each new alternative design case using our past equipment sizing, design, and cost data and scaling relationships. Furthermore, we update BOP equipment sizing and design for the NAP case using Aspen®. Vendor quotes for electric boilers are used to estimate costs for the electric boiler design case. Factory and onsite assembly and installation costs for SOEC stacks and BOP equipment are calculated using our past simplified first-principles approach. First-of-a-kind (FOAK) and N th -of-a-kind (NOAK) production maturity cost estimates are included for all results. The case with NAP stacks offers the lowest facility total capital cost (TCC, ~23% lower than base) while use of small electric boilers requires the highest TCC (~3% higher than base). H 2 production prices decrease from the base of ~$\$2.17$ /kgH 2 to ~$\$1.92$/kgH 2 for 1 GW e DC SIP facilities utilizing NAP stacks supplied by offsites steam situated in large modules and blocks for $\$0.030$/kWh e and $0.009/kWh t prices for electricity and thermal energy, respectively. We report all costs in 2021 US dollars.

Balance of plant (BOP) process equipment↗
DOE OSTI2026

NREL's 1MW Water Electrolysis Stack Performance Validation to Pilot-Scale Renewable Natural Gas Production [Slides]

NREL has designed, built, and operates a 1MW water electrolyzer balance-of-plant to support industrial partners and the U.S. Department of Energy in developing next-generation PEM stacks to reduce the cost of hydrogen production. With that hydrogen, we are developing, innovating and de-risking a biomethanation process capable of megawatt-scale deployment that upgrades biogas waste streams to produce pipeline quality renewable natural gas (RNG). Biomethanation is a two-step process using a methanogenic microorganism to convert renewable hydrogen (H 2 ) and waste carbon dioxide (CO 2 ) to renewable methane (CH 4 ) - the primary component in natural gas. Using biogenic CO 2 from biogas sources like dairies, wastewater treatment plants, and landfills allows production of this drop-in direct replacement fuel. Research projects and future R&D topics are also discussed during the presentation.

08 HYDROGEN↗
DOE OSTI2025

Understanding Reliability Trade-Offs in 1T-nC and 2T-nC FeRAM Designs

Ferroelectric random access memory (FeRAM) is a promising candidate for energy-efficient nonvolatile memory, particularly for logic-in-memory and compute-in-memory (CIM) applications. Among the available cell architectures, One-Transistor–n-Capacitor (1T-nC) and two-transistor–n-capacitor (2T-nC) FeRAMs each offer distinct trade-offs in density, scalability, and reliability. In this work, we present a comparative study of these two architectures under both dimensional scaling ( XY/Z shrinkage) and vertical integration (increasing stacked capacitors per cell). Using technology computer-aided design (TCAD) and circuit-level simulations, we analyze how scaling impacts ferroelectric capacitance, parasitic coupling, and floating-node (FN) dynamics, which together dictate sense margin (SM) and read stability. A key mitigation strategy—floating unselected capacitors—is applied to both architectures, effectively decoupling the SM from the number of stacked capacitors and enabling tractable analysis across scaling regimes. Results show that 1T-nC suffers more from charge sharing with the bitline (BL), while 2T-nC benefits from transistor isolation and stronger low-voltage sensing at the cost of increased area. By systematically evaluating these behaviors across scaling directions, this work establishes the reliability trade-offs of 1T-nC and 2T-nC cells and provides design guidelines for high-density, vertically integrated FeRAM systems.

1T-nC↗
NASA NTRS1985

A damage tolerant design parameter for graphite/epoxy laminated composites

The results of an extensive experimental investigation of the fracture behavior of notched graphite/epoxy laminates are presented. Twenty-seven laminates with different stacking sequences and laminate thicknesses have been studied. The data presented herein suggest that a damage tolerant design parameter exists that is relatively independent of ply stacking sequence and laminate thickness.

Harris, C. E.↗
DOE OSTI2023

19.32% Efficiency Polymer Solar Cells Enabled by Fine-Tuning Stacking Modes of Y-Type Molecule Acceptors: Synergistic Bromine and Fluorine Substitution of the End Groups

Here, the success of Y6-type nonfullerene small molecule acceptors (NF-SMAs) in polymer solar cells (PSCs) can be attributed to their unique honeycomb stacking style, which leads to favorable thin-film morphologies. The intermolecular interactions related to the crystallization tendency of these NF-SMAs is closely governed by their electron accepting end groups. For example, the high performance Y6 derivative L8-BO (BTP-4F) presents three types of stacking modes in contrast to two stacking modes of Y6. Hence, it is ultimately interesting to obtain more insight on the packing properties and the preferences influenced by chemical modifications such as end group engineering. This work designs and synthesizes asymmetric and symmetric L8-BO derivatives with brominated end groups and explores the stacking preferences in various modes. The asymmetric BTP-3FBr displays an optimized crystallization tendency and thin film morphology, leading to a decent power conversion efficiency (PCE) of 18.34% in binary devices and a top PCE of 19.32% in ternary devices containing 15 wt% IDIC as the second acceptor.

36 MATERIALS SCIENCE↗