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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 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Engineering Accessible Adsorption Sites in MOFs for CO 2 Capture

The overall goal of this project was to synthesize metal-organic frameworks (MOFs) with improved CO 2 adsorption and selectivity properties for potential application in removing this greenhouse gas from flue gas streams during fossil fuel processing. MOFs are an important class of 2-dimensional (2D) and 3D supramolecular coordination polymer networks that are comprised of organic linkers (ligands) and metal ion-units or clusters. They generally possess very high surface area, porosity, variable thermal stability and tunable chemistry, which make them potential candidates for CO 2 adsorption. The three specific objectives of this project were as follows: 1) To synthesize MOFs with metal ion adsorption sites in more accessible locations within the structures (towards the center of the organic linkers) in order to enhance their CO 2 adsorption characteristics; 2) To investigate the CO 2 adsorption properties of new MOFs containing pyrazine- and other nitrogen containing ligands as possible improved alternatives to known amine-functionalized MOFs; and 3) To investigate the nature of the adsorption sites and mechanism(s) by conducting computational studies on CO 2 adsorption within the MOF structures and compare the results with experimental observations. The main outcomes of this research are as follows: Nitrogen-containing ligands that possess a diaza-12-crown-4-ether moiety at the center of two phenylcarboxylic acid groups were utilized to synthesize 3D MOFs in which the added transition metal ions (i.e. Co 2+ and Mn 2+ ) were coordinated within the crown moieties. Therefore, the structures had the metal ions in more accessible locations. The new 3D structures, being non-porous however, showed negligible adsorption capacity for CO 2 . The ligand 2,3,5,6,-pyrazinetetracarboxylic acid (PZTC) was successfully used to synthesize four new MOFs, each with one of the following metal ions; Ca 2+ (1D), Zn 2+ (2D), Mn 2+ (3D) and Gd 3+ (3D), and with the dimensionality (D) indicated. The Ca-, Zn- and Mn- PZTC-based MOFs had no obvious accessible pores and showed no adsorption capacity for CO 2 . Gd-PZTC structure however, showed promising capacities of 1.0 mmol/g and 0.6 mmol/g at 273K and 298 K respectively. Another nitrogen-containing ligand explored was 2,2’-dinitro- trans-4,4’- stilbenedicarboxylic acid (DNSDC) and in combination with a co-ligand, 2,2’-bipyridine (2,2’-BPY). The combination of DNSDC with Co 2+ and Mn 2+ yielded four new thermally stable MOFs that showed significant CO 2 absorption capacities. The experimental CO 2 adsorption capacities varied among the structures, ranging between 1.8 mmol/g at 256 K and 0.8 mmol/g at 298K. The DNSDC-based structures maintained significant stability and capacities over many adsorption cycles at 298K. With 2,2’-diamino- trans-4,4’-stillbene dicarboxylic acid (DASDC) as ligand instead of DNSDC, new 3D MOF structures were also synthesized. The structures, however, were less stable, and decomposed on activation (exposure to vacuum and or solvents) and therefore showed negligible CO 2 adsorption capacities. The dinitro-stilbene based MOFs showed promising CO 2 adsorption capacities, thermal stabilities and recyclability, and therefore showed potential for application in CO 2 removal from flue gas. The research accomplishments presented herein support the Department of Energy’s (DOE) Office of Fossil Energy and the National Energy Technology Laboratory (NETL) mission in the area of research that advances the science of coal technologies, specifically carbon capture and storage. The research outcomes can guide rational design/synthesis strategies towards producing advanced materials for CO 2 capture. However, further research is needed in order to develop the materials to meet or exceed capacities and stabilities that are reported for their counterparts.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2022

Research on high power, doped titanium-niobium oxide anodes

The main objective of this project is to synthesize titanium niobium oxide (TNO) that has a nanoporous structure with porous channels for rapid lithium diffusion, enabling extreme fast charging (XFC). The focus of this project is to improve the electronic conductivity and ion diffusion coefficient in TNO to achieve high capacities under extreme fast charge conditions. In addition, electrolytes with additives will be formulated to promote stable interphase formation on the NMC cathode surface to improve long cycling stability.

25 ENERGY STORAGE↗
DOE OSTI2025

Toward Thermally Stimuli-Responsive Polymeric Vesicles Fabricated by Block Copolymer Blends for Nanocarriers

Polymeric vesicles, characterized by enhanced colloidal stability, excellent mechanical properties, controllable surface functionality, and adjustable membrane thickness, are extremely useful in nano- and bio-technology for potential applications as nanosized carriers for drugs and enzymes. However, a few preparative steps are necessary to achieve a unilamellar vesicle with a narrow size distribution. Herein, we report the spontaneous formation of unilamellar polymeric vesicles with nanometer sizes (<50 nm), fabricated by simply mixing diblock copolymers (P(EO-AGE)(2K-2K) and P(EO-AGE)(0.75K-2K)) with differing hydrophilic mass fractions in aqueous solutions. Depending on the mixing ratio of block copolymers and the temperature, the block copolymer mixtures self-assemble into various nanostructures, such as spherical and cylindrical micelles, or vesicles. The self-assembled structures of the block copolymer mixtures were characterized by small-angle neutron scattering, resulting in a phase diagram drawn as a function of temperature and the mixing condition. Notably, the critical temperature for the micelle-to-vesicle phase transition can be easily controlled by altering the mixing conditions; it decreases with an increase in the concentration of one of the block copolymers.

block copolymers↗
DOE OSTI2025

Fault Tolerant Decoding of QLDPC-GKP Codes with Circuit Level Soft Information

Concatenated bosonic-stabilizer codes have recently gained prominence as promising candidates for achieving low-overhead fault-tolerant quantum computing in the long term. In such systems, analog information obtained from the syndrome measurements of an inner bosonic code is used to inform decoding for an outer code layer consisting of a discrete-variable stabilizer code such as a surface code. The use of Quantum Low-Density Parity Check (QLDPC) codes as an outer code is of particular interest due to the significantly higher encoding rates offered by these code families, leading to a further reduction in overhead for large-scale quantum computing. Recent works have investigated the performance of QLDPC-GKP codes in detail, and the use of analog information from the inner code significantly boosts decoder performance. However, the noise models assumed in these works are typically limited to depolarizing or phenomenological noise. In this paper, we investigate the performance of QLDPC-GKP concatenated codes under circuit-level noise, based on a model introduced by Noh et al. in the context of the surface-GKP code. To demonstrate the performance boost from analog information, we investigate three scenarios: (a) decoding without soft information, (b) decoding with precomputed error probabilities but without real-time soft information, and (c) decoding with real-time soft information obtained from round-to-round decoding of the inner GKP code. Results show minimal improvement between (a) and (b), but a significant boost in (c), indicating that real-time soft information is critical for concatenated decoding under circuit-level noise. We also study the effect of measurement schedules with varying depths and show that using a schedule with minimum depth is essential for obtaining reliable soft information from the inner code.

Borah, Shantom K. [Arizona U. (main)]↗
NASA NTRS1974

Results of investigations on an 0.015-scale configuration 140A/B space shuttle vehicle orbiter model (49-0) in the NASA/Langley Research Center 8-foot transonic pressure tunnel (OA25)

Aerodynamic force and moment tests were conducted on an 0.015-scale space shuttle vehicle configuration 140A/B model (49-0) in a transonic pressure tunnel. The test was carried out at Mach numbers 0.35, 0.60, 0.80, 0.90, 0.98, and 1.20, and at Reynolds numbers ranging from 1.90 million per foot to 3.97 million per foot, depending on tunnel total pressure capability and model structural limits. The model attitude was varied in angle-of-attack from minus 2 deg to +22 deg at 0 deg and 5 deg angles of yaw, and in angle-of-sidelip from minus 5 to +10 deg at 0 deg, 7.5 deg, and 15 deg angles of pitch. The purpose of this test was to establish and verify longitudinal and lateral-directional characteristics of the 140A/B Configuration Orbiter and to determine the effects of surface deflections on vehicle performance, stability, and control.

Nichols, M. E.↗
NASA NTRS1974

Studies of liquid floating zones on SL-IV, the third Skylab mission

The behavior of liquid floating zones in a zero-gravity environment was studied by Dr. E. Gibson on SL-4. These experiments were designed from the results of previous work on floating zones in a simulated zero-gravity model. Molten floating zones are used on earth for the crystal growth and zone refining of reactive materials. The Skylab studies give some insight into the problems associated with the development of the technique for the future space processing of materials. Preliminary results are presented on the stability of the liquid zone surface under static, rotational and vibrational conditions without gravitational constraints.

Carruthers, J. R.↗
NASA NTRS1976

A study of a plume induced separation shock wave, including effects of periodic plume unsteadiness

A wind tunnel investigation was conducted to study the flow field in which separation is caused by an expanding plume, with emphasis on effects associated with periodic unsteadiness in the plume. The separation shock was photographed with high speed motion pictures, from which mean shock position and excursion data were reported. Pressure fluctuations were measured beneath the separation shock. A response of the separation shock to plume periodic unsteadiness was identified, and the magnitude of a corresponding transfer function was defined. Small harmonic effects in plume response to periodic unsteadiness were noted. The stabilizing effect of a lateral surface protuberance near the separation shock wave was investigated. The protuberance configuration was a lateral circular cylinder, and various diameters, all less than the boundary layer thickness, were employed.

Doughty, J. O.↗
NASA NTRS1983

An experimental study of pressures on 60 deg Delta wings with leading edge vortex flaps

An experimental study was conducted in the Virginia Tech Stability Wind Tunnel to determine surface pressures over a 60 deg sweep delta wing with three vortex flap designs. Extensive pressure data was collected to provide a base data set for comparison with computational design codes and to allow a better understanding of the flow over vortex flaps. The results indicated that vortex flaps can be designed which will contain the leading edge vortex with no spillage onto the wing upper surface. However, the tests also showed that flaps designed without accounting for flap thickness will not be optimum and the result can be oversized flaps, early flap vortex reattachment and a second separation and vortex at the wing/flap hinge line.

Marchman, J. F., III↗
NASA NTRS1984

Helicopter Anti-Torque System Using Strakes

A helicopter is disclosed with a system for controlling main-rotor torque which reduces the power and size requirements of conventional anti-torque means. The torque countering forces are generated by disrupting the main rotor downwash flowing around the fuselage. The downwash flow is separated from the fuselage surface by a strake positioned at a specified location on the fuselage. This location is determined by the particular helicopter wash pattern and fuselage configuration, generally being located between 20 deg before top dead center (TDC) and 80 deg from TDC on the fuselage side to which the main rotor blade approaches during rotation. The strake extends along the fuselage from the cabin section to the aft end and can be continuous or separated for aerodynamic surfaces such as a horizontal stabilizer.

Kelley, H. L.↗
NASA NTRS1983

Incorporating geometric and radiative effects into infrared scanning computer analysis

A NASA program, the SILTS experiment (Shuttle Infrared Leeside Temperature Sensing) will utilize an infrared scanning system mounted at the tip of the vertical stabilizer to remotely measure the surface temperature of the leeside of the Space Shuttle during entry from orbit. Scans of the fuselage and one wing will be made alternately. The experiment will correlate real full scale data to ground-based information. In order to quantitatively assess the temperature profile of the surface, an algorithm is required which incorporates the Space Shuttle shape, location of specific materials on the surface, and the measurement geometry between the camera and the surface. This paper will discuss the algorithm.

Myrick, D. L.↗
NASA NTRS1987

Compatability of dispersion-strengthened platinum with resistojet propellants

Resistojets for the Space Station require long life and multipropellant capability. The choice of available materials to meet these requirements is limited. Dispersion-strengthened platinum was selected. Past results indicated that it should be suffieiently inert in candidate propellant environments and should be capable of operating at moderate temperatures for extended periods. A series of propellant compatibility tests was done with platinum strengthened with either yttria or zirconia. Data presented included the results of 1000-hr tests in CO2, H2, ammonia (NH3), N2, steam, hydrazine (N2H4), and methane (CH4); and 2000-hr tests in H2 and NH3. The platinum samples were tested at 1400 C in CO2, H2, NH3, N2, steam, and N2H4; at 500 C in CH4; and at 800 C in N2H4. The mass-loss results indicated material life, exptrapolated from experimental mass-loss data, in excess of 100 000 hr in all environments except steam and N2H4, where it was greater than or =45000 hr. Generally, on the basis of mass loss, there were no compatibility concerns in any of the environments considered. Optical and scanning electron microscopy were used to determine the effect of propellants on the material surface and to evaluate material stability.

Whalen, Margaret V.↗
NASA NTRS1988

Dendritic growth in the presence of convection

The motion of the freezing front between a dendritic crystal and a supercooled liquid is studied using an interface evolution equation derived from a boundary integral transformation of the transient convective-diffusion equation. A new steady-state theory is introduced that incorporates the effects of convection in dendritic growth. It is shown that in the absence of capillary effects the shape of the crystal-melt interface is a paraboloid of revolution, similar to that found in situations where diffusion is the sole heat transfer mechanism. A relation between the supercooling, the product of the tip velocity and tip radius, and the strength of the flow is derived which reduces to the well-known Ivantsov theory in the absence of convection. A non-linear interface-tracking algorithm is developed and used to study the temporal and spatial evolution of the dendritic interface. The important role of capillarity and convection on the interface dynamics is established and the response of the interface to finite amplitude disturbances is examined for the first time. Tip splitting is identified as the dominant destabilization mechanism in the limit of zero surface tension. Finite surface tension leads to interface stabilization, irrespective of the magnitude and structure of the external perturbations. Finally, convection significantly decreases the magnitude of the freezing velocity.

Beaghton, Pantelis John↗
NASA NTRS1988

Effect of surface catalysis on heating to ceramic coated thermal protection systems for transatmospheric vehicles

This paper describes the effect of surface catalysis on the heat transfer rate to the heat shield of a typical Transatmospheric Vehicle (TAV) during ascent and atmospheric entry. Surface kinetics and optical properties obtained from arc-jet tests on candidate thermal protection systems (coated metals) were used in a reacting boundary layer code to estimate the heating distribution along the surface of a TAV. Thermochemical stability of the coatings is described in terms of reduction in emittance and loss of opacifiers from the coatings during the arc-jet tests.

Stewart, David A.↗
NASA NTRS1988

Eigenstructure assignment for the control of highly augmented aircraft

Eigenstructure assignment is utilized to design flight control laws for aircraft with many control effectors. It is shown that a previous eigenstructure design for the flight propulsion control coupling (FPCC) aircraft lateral dynamics with three control surfaces exhibits a lack of stability robustness because the control distribution matrix is nearly rank-deficient. A method is mapped back, reducing the control space to two dimensions by using the singular value decomposition. After the design is complete, the controller is mapped back to the original three-dimensional control space. This design approach yields a controller with both smaller gains and improved multivariable stability margins at the aircraft inputs. An interesting characteristics of the control mapping, as applied to the given example, is that the most effective inputs have the larger gains while the less effective inputs have smaller gains.

Sobel, Kenneth M.↗
NASA NTRS1991

CFD validation of a supersonic laminar flow control concept

A three-dimensional Navier-Stokes code is used in conjunction with a linear compressible stability analysis code to develop a numerical procedure for prediction of laminar flow transition. The procedure is applied to a modified F-16XL fighter with a laminar flow control glove at supersonic speed. Details of boundary layer stability analysis indicate that, computationally, laminar flow could be realized on the highly swept wing in the absence of the leading edge attachment-line contamination. Effects of the three-dimensionality of the flow were shown to be important in the boundary layer stability analysis. The numerically predicted surface pressures compare favorably with the flight test data.

Woan, Chung-Jin↗
NASA NTRS1992

Determination of the oxidative stability of perfluoropolyalkyl ethers and correlation with chemical structure

The oxidative stabilities of several perfluoropolyalkyl ethers (PFPAE) with related chemical structures were determined by thermal gravimetric analysis and correlated with their chemical structures. These results show that oxidative stability increases as the number of difluoroformal groups decreases and as trifluoromethyl substituents are added. They are also consistent with a recently proposed intramolecular disproportionation reaction mechanism involving coordination of successive ether oxygens to a Lewis acid. Since polytetrafluoroethylene contains no oxygen, it provides an indication of the upper limit to oxidative stability of PFPAE fluids. These results also show that oxidative decomposition of PFPAE fluids requires the presence of an active metal as well as air. Consequently, it may be possible to minimize decomposition and thus improve oxidative stability by passivating reactive metal surfaces.

Helmick, Larry S.↗
NASA NTRS1992

Telescopes for a lunar outpost

This paper presents an overview of lunar-based telescopes. It begins with a review of the impressive attributes of the moon for astronomy which include a hard vacuum, seismic stability, low gravitational field, large surface area, dark and radio-quiet skies on the far-side, cold craters at the poles, and an abundance of raw materials. These attributes, coupled with the availability of technicians at a lunar outpost, make the moon the most attractive site for the next generation of space-based observatories. It is argued that modest, light-weight instruments such a generic 1-m optical/UV/IR telescope and a low radio frequency phased array are well suited for early deployment on the moon. More advanced concepts such as a 16-m filled aperture telescope and an optical interferometer will make unprecedented strides in sensitivity and resolution. Although complex, such telescopes are well-suited to an evolutionary construction and deployment scheme.

Burns, Jack O.↗