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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Rapid Development of Instrument Thermal Models: Perspectives and Guidelines from NASA Goddard’s Instrument Design Laboratory

The Instrument Design Laboratory (IDL), part of NASA Goddard Space Flight Center’s Integrated Design Center (IDC), is a concurrent and collaborative environment which allows for rapid development of science instrumentation concepts within the span of less than two weeks. Science goals set by a Principal Investigator from government, industry or academia are translated into engineering requirements, from which a team of engineers spanning multiple disciplines use an established study process and a suite of analysis tools to work towards an instrument point design. As part of this process, a staff thermal engineer is tasked with designing a thermal control system which meets all incoming thermal requirements, while iterating real-time with other subsystems to ensure compatibility and functionality as a completed system. Thermal engineers on spaceflight projects typically have weeks or months to develop thermal models. However, the severe time limitation in this conceptual study setting makes thermal design particularly difficult, as rapid thermal modeling solely over the span of a few days is required to develop the instrument thermal design and understand the performance over its intended mission, especially if the instrument concept contains multiple thermal challenges such as dynamic environments or high heat dissipating components. In this paper, the authors provide a condensed guide for the most efficient ways to develop thermal models and conduct thermal analysis within the span of one-to-two weeks, as informed by decades of design experience and best practices in the IDL. The authors also focus on quick methods for determining worst-case thermal environments, deciding which modeling details are essential at this early phase, and quantifying the engineering resources necessary for thermal control. This paper concludes with specific thermal design tips for different instrument types across the electromagnetic spectrum.

Kan Yang↗
NASA NTRSDate not supplied

Feasibility of Micro-Multilayer Multifunctional Electrical Insulation (MMEI) System for High Voltage Applications

The newly patented micro-multilayer multifunctional electrical insulation (MMEI) system was developed for future electric aircraft applications which critically require lightweight but high voltage (HV), high temperature, and corona or partial discharge (PD) resistant insulation. During the initial development stages, the concept and practicability of the MMEI system were successfully validated with its exceptionally high dielectric breakdown voltages. The multilayer structures were optimized in terms of material type, individual layer thickness, and overall layer configuration along with potential mechanisms identified for its superior performance. Subsequently, scalability, manufacturability, and commercial applicability of the MMEI system were demonstrated with the 1 meter long, 3-phase HV, high power (HP) bus bar prototypes. Two prototypes, one with the conventional SOA insulation system including Mica sheet and the other with an optimized MMEI, were designed, fabricated, and tested successfully. Both prototypes passed both HiPot and PD tests up to the highest test voltage available, 15 kVAC, although the latter showed a slight increase in PD activities at 12.5 kV. However, the prototype with MMEI was 15% lighter or 12% thinner than the other one. Current efforts to significantly enhance the PD resistance of the MMEI system by employing semiconductive shielding layers, which can be also multifunctional, e.g., electromagnetic interference shielding, moisture blocking, heat dissipation, for various HV applications are also discussed in this paper.

Novel Electrical Insulation↗
NASA NTRSDate not supplied

Development and Application of a Novel Calorimetry Technique for the Study of Lithium-Ion Cell Thermal Runaway

Lithium-ion battery technology is widely used and is attractive due to demonstrated specific energies in the 200-300 W-hr/kg range. The excellent, mass-efficient energy storage capability of lithium-ion batteries has led to their use on many aerospace platforms. However, lithium-ion batteries can exhibit thermal runaway behavior wherein stored electrochemical energy is released rapidly as a result of thermal or mechanical failure, electrochemical abuse, internal or external short circuiting. A single cell undergoing thermal runaway within a battery has the potential to induce thermal runaway in adjacent cells if heat dissipation is not properly managed and can result in a catastrophic failure of the battery. Designing batteries that are resistant to thermal runaway propagation requires an understanding of, not only, total energy yield but also the means by which that energy is liberated from the cell. While Accelerating Rate Calorimetry and other techniques provide total thermal runaway energy yield, they do not provide the fractional breakdown of energy liberated via conduction through the cell casing from that which is vented from the cell as hot gases and effluents. Such data are needed to inform battery thermal design and analysis. To measure the total energy yield, the fraction conducted through the cell casing, and the fraction lost due to gases and effluents, NASA developed Fractional Thermal Runaway Calorimetry (FTRC). Two calorimeters have been developed and demonstrated, the Small-format- and Large-format Fractional Thermal Runaway Calorimeters (S-FTRC and L-FTRC, respectively). The technique has been successfully applied to small- and large-format cells (2.4-3.5 Ah and >100 Ah capacity, respectively) and has given new insights into Li-ion cell thermal runaway. Development of the calorimeters is discussed and results from the initial thermal runaway testing campaigns are presented.

Lithium-Ion Cell↗
NASA NTRSDate not supplied

Feasibility of Micro-Multilayer Multifunctional Electrical Insulation (MMEI) System for High Voltage Applications

The newly patented micro-multilayer multifunctional electrical insulation (MMEI) system was developed for future electric aircraft applications which critically require lightweight but high voltage (HV), high temperature, and corona or partial discharge (PD) resistant insulation. During the initial development stages, the concept and practicability of the MMEI system were successfully validated with its exceptionally high dielectric breakdown voltages. The multilayer structures were optimized in terms of material type, individual layer thickness, and overall layer configuration along with potential mechanisms identified for its superior performance. Subsequently, scalability, manufacturability, and commercial applicability of the MMEI system were demonstrated with the 1 meter long, 3-phase HV, high power (HP) bus bar prototypes. Two prototypes, one with the conventional SOA insulation system including Mica sheet and the other with an optimized MMEI, were designed, fabricated, and tested successfully. Both prototypes passed both HiPot and PD tests up to the highest test voltage available, 15 kVAC, although the latter showed a slight increase in PD activities at 12.5 kV. However, the prototype with MMEI was 15% lighter or 12% thinner than the other one. Current efforts to significantly enhance the PD resistance of the MMEI system by employing semiconductive shielding layers, which can be also multifunctional, e.g., electromagnetic interference shielding, moisture blocking, heat dissipation, for various HV applications are also discussed in this paper.

Novel Electrical Insulation↗
NASA NTRS2024

Flexural Fatigue Testing and Qualification of Hybrid PAN-pitch Composite Materials with High Through-Thickness Thermal Conductivity

Carbon-fiber-reinforced polymers (CFRPs) considered for motor components within future electric vertical takeoff and landing (eVTOL) vehicles require not only a high strength-to-weight ratio but also a high through-thickness thermal conductivity (TC) to dissipate heat. Previously, CFRPs incorporating pitch CF interleaves demonstrated an increased through-thickness TC relative to the baseline composite, but the effect on flexural fatigue life was not evaluated. For this work, T700S/TC275–1 braided carbon fiber/epoxy prepreg baseline (no interleave), YSH–60A pitch interleave, and YS–80A pitch interleave configurations were tested for fatigue life. A combination of ASTM International Standards D7264 and D3479 were used to develop a reliable testing method. An Instron® (Illinois Tool Works Inc.) 8501 servohydraulic system with a fatigue test fixture was set up with a 16:1 span:thickness ratio, load ratio R set to 0.1, and frequency of 4 Hz. High-cycle fatigue testing was completed, and it was found that YSH–60A interleave performed slightly better than YS–80A below 100,000 cycles but showed no differences above 100,000 cycles. In all cases, the baseline CFRP had superior fatigue life performance both in terms of stress handled and total cycles to failure. These fatigue testing data will inform future use of hybrid CFRP materials by highlighting the tradeoff between increased through-thickness TC and fatigue life. Testing guidelines, equipment, and parameters for static and fatigue tests were successfully outlined for CFRPs.

composites↗
NASA NTRS2025

The Shape Effect: Influence of 1D and 2D Boron Nitride Nanostructures on the Radiation Shielding, Thermal, and Damping Properties of High-Temperature Epoxy Composites

In space exploration, lightweight multifunctional materials capable of shielding neutron radiation, dissipating heat, and providing damping are essential. Polymer composites reinforced with boron nitride (BN) nanomaterials—specifically one-dimensional boron nitride nanotubes (BNNTs) and two-dimensional boron nitride nanoplatelets (BNNPs)—offer promising solutions. This study investigates how BN nanomaterial morphology influences the performance of high-temperature (HT) epoxy composites. We developed ultralightweight, three-dimensional BN foams comprising 1D BNNTs, 2D BNNPs, and hybrid 1D BNNT/2D BNNP structures via freeze-drying, then infiltrated them with HT epoxy to form dense composites. The BNNT foam exhibited the highest neutron radiation shielding, with a mass absorption coefficient of 26.64 cm2 g −1 , outperforming the hybrid foam (18.18 cm 2 g −1 ) and the BNNP foam (11.12 cm 2 g −1 ). A similar trend was observed in the HT epoxy composites; incorporating these foams at least doubled the mass absorption coefficient compared to the neat polymer. In terms of thermal conductivity, the BNNT/BNNP foam-epoxy composite achieved the highest value of 0.34 W m −1 K −1 , a 2.13-fold increase over neat HT epoxy. The BNNT/BNNP foam-epoxy composites also improved by 1.88 and 1.75 times, respectively. Mechanical testing revealed that BNNP foams withstood the highest loads during nanoindentation (3.53 kN), followed by BNNT/BNNP foams (1.93 kN) and BNNT foams (1.56 kN). All BN foam-epoxy composites exhibited enhanced damping properties, with tan δ increasing by at least 30 % compared to neat HT epoxy. These findings elucidate the impact of BN nanomaterial morphology on the multifunctional performance of HT epoxy composites, offering insights for developing high-performance, tailorable materials for demanding environments.

Kazue Orikasa↗
NASA NTRS1992

Two dimensional PIC simulations of plasma heating by the dissipation of Alfven waves

Two dimensional plasma particle simulations of the evolution of large amplitude circularly polarized Alfven waves propagating parallel to the magnetic field show that the waves decay via both one- and two- dimensional parametric decay instabilities. For parameters studied, one-dimensional processes dominate the simulations, but two-dimensional decay processes, including the recently predicted filamentation instability are also observed. The daughter waves generated by the parametric decay are primarily damped by the ions, leading to ion heating. The parametric decay processes efficiently convert the ordered fluid ion motion in the Alfven wave into ion thermal energy. These processes may be important for the dissipation of Alfven waves in the solar wind, the corona and other space plasma environments. The computations were performed on the Intel Touchstone parallel supercomputer.

Liewer, P. C.↗
NASA NTRS1976

Oceanic lithosphere and asthenosphere: The thermal and mechanical structure

A coupled thermal and mechanical solid state model of the oceanic lithosphere and asthenosphere is presented. The model includes vertical conduction of heat with a temperature dependent thermal conductivity, horizontal and vertical advection of heat, viscous dissipation or shear heating, and linear or nonlinear deformation mechanisms with temperature and pressure dependent constitutive relations between shear stress and strain rate. A constant horizontal velocity u sub 0 and temperature t sub 0 at the surface and zero horizontal velocity and constant temperature t sub infinity at great depth are required. In addition to numerical values of the thermal and mechanical properties of the medium, only the values of u sub 0, t sub 0 and t sub infinity are specified. The model determines the depth and age dependent temperature horizontal and vertical velocity, and viscosity structures of the lithosphere and asthenosphere. In particular, ocean floor topography, oceanic heat flow, and lithosphere thickness are deduced as functions of the age of the ocean floor.

Schubert, G.↗
NASA NTRS1981

Dissipation and turbulent heating of plasma in Jupiter's magnetosphere

Voyager 1 observations of plasma waves in the dayside Jovian magnetosphere which show a correlation with measurements of localized concentrations of cool thermal plasma are presented. This moderately intense broadband electrostatic noise is shown to be of sufficient intensity to accelerate superthermal ions to energies approximately 1 keV and higher. This process can account for the extensive heating of plasma in the magnetosphere and can energize a fraction of heavy ions to injection threshold for a high-energy second stage acceleration mechanism. A brief discussion of the relation of this noise to Jovian magnetospheric dynamics is included.

Barbosa, D. D.↗
NASA NTRS2018

Rechargeable Battery Auto-Cycler Requiring Lower Power and Dissipating Reduced Waste Heat

A battery charger system includes a power supply and a switch connected to the power supply wherein the switch has a first switch half and a second switch half. First and second batteries are selectively connected to the power supply via the switch. The first and second switch halves are moved between a plurality of operational positions to fully charge the first battery, discharge the first battery into the second battery, discharge the second battery into the first battery, and fully charge the second battery.

Hanson, Thomas David↗
NASA NTRS1981

Chromospheric and coronal heating mechanisms

Dissipation mechanisms in the chromosphere were examined. The problem of a heat flux from a cool region of the star to a hot region of the star, which violates our second law of thermodynamics is discussed. It is suggested that this is caused by a nonthermal energy flux. While convection transports the thermal flux, a very small percentage is converted into a nonthermal flux. The major part of the outgoing convective energy is turned back into the radiation field which gets decoupled from the star when the star becomes transparent and the radiant energy escapes to space. The small nonthermal flux is transmitted upwards and becomes the dominant energy flux still coupled to the star. The importance of recycling of energy via advection and conduction is emphasized.

Leibacher, J.↗
NASA NTRS1993

Thermal control of ice-stream margins

The thermal balance at the base of an ice sheet near an ice-stream margin was investigated theoretically. Specifically, conditions such that the base of the ice sheet would be frozen in the absence of heat generated by the ice motion were investigated. The base of the ice stream is maintained at melting as a result of high dissipation of heat at the base associated with its fast motion over the bed. Heat dissipation in the inter-ice-stream ridge ice is presumed to be too small to maintain melting conditions on the bed there. Two opposing effects can be identified near the shear margin separating the fast and slow motions. Because the velocity of an ice stream falls off toward its margin, there is a near margin heat deficit zone where the heat generated at the bed is not, by itself, sufficient to maintain melting conditions. Without some counteracting process, the base could freeze inward toward the ice stream and cause it to narrow. The marginal shearing generates heat within the ice above the bed. This heat produces a thermal shielding effect that tends to warm the bed on both sides of the boundary between the fast and slow motion. This shielding effect, if strong enough, could produce a thawed zone beyond the fast/slow boundary. If melting at the bed by itself allows fast motion, then the ice stream would be free to widen. A coupled mass and heat flow model is being developed to examine these competing processes. Preliminary calculations using available information for boundary conditions appropriate for Ice Stream B predict that the shielding effect is most important. This tentative result suggests that thermal conditions are such that the ice stream could widen unstably. Other constraints would be required to stabilize the width. Possible factors could be bed morphology beneath ridges that does not allow fast motion even in thawed conditions, or inward advection of cold ice from the ridges across the margin and into the ice stream, which suppresses the shielding effect. The unknown geothermal heat flow beneath ice streams and inter ice-stream ridges is a major uncertainty in doing these calculations.

Raymond, Charles F.↗
NASA NTRS2007

Dynamics of Nanoscale Grain-Boundary Decohesion in Aluminum by Molecular-Dynamics Simulation

The dynamics and energetics of intergranular crack growth along a flat grain boundary in aluminum is studied by a molecular-dynamics simulation model for crack propagation under steady-state conditions. Using the ability of the molecular-dynamics simulation to identify atoms involved in different atomistic mechanisms, it was possible to identify the energy contribution of different processes taking place during crack growth. The energy contributions were divided as: elastic energy, defined as the potential energy of the atoms in fcc crystallographic state; and plastically stored energy, the energy of stacking faults and twin boundaries; grain-boundary and surface energy. In addition, monitoring the amount of heat exchange with the molecular-dynamics thermostat gives the energy dissipated as heat in the system. The energetic analysis indicates that the majority of energy in a fast growing crack is dissipated as heat. This dissipation increases linearly at low speed, and faster than linear at speeds approaching 1/3 the Rayleigh wave speed when the crack tip becomes dynamically unstable producing periodic dislocation bursts until the crack is blunted.

Yamakov, V.↗
NASA NTRS2004

Texturing Carbon-carbon Composite Radiator Surfaces Utilizing Atomic Oxygen

Future space nuclear power systems will require radiator technology to dissipate excess heat created by a nuclear reactor. Large radiator fins with circulating coolant are in development for this purpose and an investigation of how to make them most efficient is underway. Maximizing the surface area while minimizing the mass of such radiator fins is critical for obtaining the highest efficiency in dissipating heat. Processes to develop surface roughness are under investigation to maximize the effective surface area of a radiator fin. Surface roughness is created through several methods including oxidation and texturing. The effects of atomic oxygen impingement on carbon-carbon surfaces are currently being investigated for texturing a radiator surface. Early studies of atomic oxygen impingement in low Earth orbit indicate significant texturing due to ram atomic oxygen. The surface morphology of the affected surfaces shows many microscopic cones and valleys which have been experimentally shown to increase radiation emittance. Further study of this morphology proceeded in the Long Duration Exposure Facility (LDEF). Atomic oxygen experiments on the LDEF successfully duplicated the results obtained from materials in spaceflight by subjecting samples to 4.5 eV atomic oxygen from a fixed ram angle. These experiments replicated the conical valley morphology that was seen on samples subjected to low Earth orbit.

Raack, Taylor↗
NASA NTRS1997

On the Potential Impact of Daytime Surface Sensible Heat Flux on the Dissipation of Martian Cold Air Outbreaks

The Martian daytime soil surface temperature is governed primarily by the net irradiance balance and surface soil heat flux. Thus the outbreak of a cold air mass generates increased sensible heat flux that is conducive to daytime dissipation of the cold air mass thermal characteristics. Conceptual and scaling evaluations of this dissipation are provided while comparison is made with similar situations on Earth. It is estimated that sensible heat flux contribution to the dissipation of the original thermal structure of the cold air could be three times larger than the corresponding situation on Earth. Illustrative numerical model simulations provide scaling of the potential impact on the dissipation of cold air masses for various combinations of background wind speed and latitudes.

Segal, M.↗
NASA NTRS1991

Electronic Dipstick

Lake-Tronic's Negative Thermistor Coefficients (NTC) prevent engine nozzles in the Space Shuttle Orbiter from swinging from side to side changing the thrust line. This technology has been adapted to an Electronik Dipstick, used to automatically monitor automotive fluid levels. NTC's are placed at predetermined levels in the dipstick and heated. Contact with fluids dissipates the heat creating a resistance change, which is analyzed by a microprocessor. Installation is simple, and additional applications are under consideration. This product is no longer manufactured.

Source record↗