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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Comments on the present state and future directions of PDF methods

The one point probability density function (PDF) method is examined in light of its use in actual engineering problems. The PDF method, although relatively complicated, appears to be the only format available to handle the nonlinear stochastic difficulties caused by typical reaction kinetics. Turbulence modeling, if it is to play a central role in combustion modeling, has to be integrated with the chemistry in a way which produces accurate numerical solutions to combustion problems. It is questionable whether the development of turbulent models in isolation from the peculiar statistics of reactant concentrations is a fruitful line of development as far as propulsion is concerned. There are three issues for which additional viewgraphs are prepared: the one point pdf method; the amplitude mapping closure; and a hybrid strategy for replacing a full two point pdf treatment of reacting flows by a single point pdf and correlation functions. An appeal is made for the establishment of an adequate data base for compressible flow with reactions for Mach numbers of unity or higher.

Obrien, E. E.↗
NASA NTRS1991

The cyclization of arabinosyladenine-5-prime-phosphorimidazolide

When arabinosyladenine-5-prime-phosphorimidazolide is allowed to decompose in aqueous solution at room temperature and pH 7.2, depending on the buffer, 5-24 percent is converted to the 2-prime,5-prime-cyclic phosphate (V). Although the extent of cyclization is much greater than for adenosine-5-prime-phosphorimidazolide, cyclization is less efficient than hydrolysis and so would not substantially decrease the efficiency of condensation reactions in aqueous solution. The significance of this result for prebiotic chemistry is discussed.

Harada, Kazuo↗
NASA NTRS1993

A convective and radiative heat transfer analysis for the FIRE II forebody

A Navier-Stokes flowfield solution method (LAURA code) using finite-rate chemistry and two-temperature thermal nonequilibrium was used in combination with two nonequilibrium radiative heat transfer codes to calculate heating for the FIRE II vehicle. An axisymmetric model of the actual body shape was used. One radiative heating code (NEQAIR) was used in uncoupled fashion with the flowfield solver's energy equations, while the other code (LORAN) was used in both coupled and uncoupled variations. Several trajectory points ranging from highly nonequilibrium flow to near-equilibrium flow were used for a study of both convective and radiative heating over the vehicle. Considerable variation in radiative heating was seen at the extremes, while agreement was good in the intermediate trajectory points. Total heat transfer calculations gave good comparison until the peak heating trajectory points were encountered, and returned to good agreement for the last two equilibrium points.

Greendyke, Robert B.↗
NASA NTRS2003

Workshop on Cometary Dust in Astrophysics

The paper include contribution of each Lunar and Planetary Institute. Contents include the following: Mass flux in the ancient Earth-Moon system and benign implications for the origin of life on Earth. In-situ analysis of complex organic matter in cometary dust by ion microprobe. Pristine presolar silicon carbide. Infrared spectra of melilite solid solution. Comet observations with SIRTF. Ice and carbon chemistry in comets. The nature in interstellar dust. Modeling the infrared emission from protoplanetary dust disks.

Source record↗
NASA NTRS2003

Carbon Nanotube Synthesis in a Flame with Independently Prepared Laser-Ablated Catalyst Particles

Laser ablation has been used ex situ to create metal nanoparticles for introduction into a reactive pyrolysis flame. By prior synthesis of the metal nanoparticles, the effects of the reactive gases can be clearly separated from the pyrolysis chemistry of a solvent carrier, as when nebulized solutions are used. Moreover, varying reactivity issues associated with particle growth and size are bypassed. Our results show that Fe selectively reacts with CO to produce nanotubes, whereas Ni selectively reacts with C2H2 to produce nanofibers. These observations are interpreted through the donation and withdrawal of electron density between the adsorbate's molecular orbitals and surface atoms of the metal nanoparticle. The rate of reaction of Ni with only C2H2 is found to be greater than the rate with C2H2 and CO. This suggests that CO inhibits the Ni-catalyzed reaction.

Nanotubes, Carbon/chemistry/ultrastructure↗
NASA NTRS2005

ISS Internal Active Thermal Control System (IATCS) Coolant Remediation Project

The IATCS coolant has experienced a number of anomalies in the time since the US Lab was first activated on Flight 5A in February 2001. These have included: 1) a decrease in coolant pH, 2) increases in inorganic carbon, 3) a reduction in phosphate buffer concentration, 4) an increase in dissolved nickel and precipitation of nickel salts, and 5) increases in microbial concentration. These anomalies represent some risk to the system, have been implicated in some hardware failures and are suspect in others. The ISS program has conducted extensive investigations of the causes and effects of these anomalies and has developed a comprehensive program to remediate the coolant chemistry of the on-orbit system as well as provide a robust and compatible coolant solution for the hardware yet to be delivered. The remediation steps include changes in the coolant chemistry specification, development of a suite of new antimicrobial additives, and development of devices for the removal of nickel and phosphate ions from the coolant. This paper presents an overview of the anomalies, their known and suspected system effects, their causes, and the actions being taken to remediate the coolant.

Morrison, Russell H.↗
NASA NTRSDate not supplied

Boundary Layer Analysis of Shock Tube Flows

Shock tubes offer a controlled environment to reproduce kinetic and radiative phenomena characteristic of atmospheric entry flows under ground-test conditions. The boundary layer developing behind the incident shock wave determines the available test time, influences particle residence times important for similarity scaling, and can affect radiative energy transport. In this study, we couple a quasi-1D space marcher with the compressible boundary-layer equations to numerically compute the post-shock flow in a shock frame of reference for various test gas mixtures representative of different planetary atmospheres. The solvers are individually verified against CFD simulations and analytical correlations available in the literature. Coupled solutions are computed for a finite-rate chemistry in the boundary layer and a non-catalytic isothermal wall. Results yield refined estimates of the maximum separation distance, as well as insights into concentration profiles of relevant species within the boundary layer.

Andrea Fagnani↗
DOE OSTI2024

Nanopore Confinement of C-H-O Mixed-Volatile Fluids Relevant to Subsurface Energy Systems

The overarching goal of OU’s contribution to the project was to use novel computational approaches to quantify the effect of variable nanopore features (pore size, volume, topology, and chemistry) and the presence of water or salt solutions on the sorption and transport of carbon-bearing fluids. To achieve this goal OU collaborators tested test two related hypotheses: • The transport of water and aqueous electrolytes in nanopores is controlled by pore size, pore wall composition, and the type of salt – structure-maker (e.g., CaCl 2 ) versus structure-breaker (e.g., NaCl) that affect the hydrogen-bonding network. • The structure, solubility, and transport of carbon-bearing molecules in water or aqueous electrolyte-filled nanopores are controlled by the substrate type including degree of hydration, and pore features, and regulated by the hydration structure of the guest molecules.

58 GEOSCIENCES↗
NASA NTRS1994

An application of a two-equation model of turbulence to three-dimensional chemically reacting flows

A numerical study of three dimensional chemically reacting and non-reacting flowfields is conducted using a two-equation model of turbulence. A generalized flow solver using an implicit Lower-Upper (LU) diagonal decomposition numerical technique and finite-rate chemistry has been coupled with a low-Reynolds number two-equation model of turbulence. This flow solver is then used to study chemically reacting turbulent supersonic flows inside combustors with synergetic fuel injectors. The reacting and non-reacting turbulent combustor solutions obtained are compared with zero-equation turbulence model solutions and with available experimental data. The hydrogen-air chemistry is modeled using a nine-species/eighteen reaction model. A low-Reynolds number k-epsilon model was used to model the effect of turbulence because, in general, the low-Reynolds number k-epsilon models are easier to implement numerically and are far more general than algebraic models. However, low-Reynolds number k-epsilon models require a much finer near-wall grid resolution than high-Reynolds number models to resolve accurately the near-wall physics. This is especially true in complex flowfields, where the stiff nature of the near-wall turbulence must be resolved. Therefore, the limitations imposed by the near-wall characteristics and compressible model corrections need to be evaluated further. The gradient-diffusion hypothesis is used to model the effects of turbulence on the mass diffusion process. The influence of this low-Reynolds number turbulence model on the reacting flowfield predictions was studied parametrically.

Lee, J.↗
DOE OSTI2023

A comparative study of solute trapping in Fe-(33–45 at%) Cu alloys manufactured by laser directed energy deposition

The high cooling rates in laser directed energy deposition (DED-LB) of alloys lead to substantial amounts of solute trapping as solute atoms cannot diffuse away from the solid/liquid interface before it advances. In some concentrated alloys, this results in supersaturated solid phases that form nanoscale hierarchical microstructures when the solute atoms precipitate out during reheating from subsequent laser passes. We choose the Iron-Copper (Fe-Cu) binary alloy as model system as it is chemically homogeneous in the liquid phase and has negligible solid solubility at room temperature. Two alloys with nominal compositions in atomic (at.) %, Fe67Cu33 and Fe55Cu45, were manufactured using DED-LB. Scanning transmission electron microscopy (STEM), energy dispersive spectroscopy (EDS) and wavelength dispersive spectroscopy (WDS) were used to characterize the nanostructures and heterogeneous chemical compositions. A non-equilibrium solute partitioning model was used to compute the supersaturated chemistries of the constituent phases and validated with experimentally measured compositions. The measured phase compositions of the two alloys were very similar, at roughly 12 at.% Cu and 4 at.% Fe in the α(bcc)-Fe and ε(fcc)-Cu phases respectively, despite having different processing parameters and mechanical behavior. This indicates that the total thermal history, that depends on both the processing parameters and laser scan pattern, plays a stronger role on the final microstructure evolution than just the initial quantity of trapped solute. In addition, we find that current non-equilibrium solute partitioning models applied on the continuum scale fall short of predicting accurate quantitative phase compositions in concentrated alloys, although the qualitative trends are captured correctly.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

DirectINJECT: Dosing Systems for Concentrated Liquid Biocides

Reliable and mass-efficient techniques for biocide dosing are necessary to enable residual microbial control in spacecraft potable water systems. DirectINJECT is an approach to provide residual microbial control by injection of concentrated aqueous biocide solution (e.g., highly soluble silver salt), and associated dosing systems technology developments. This would allow for well-controlled liquid biocide injection that requires low consumable mass and is insensitive to the chemistry of the target water. With a 40 g Ag+/l solution, required dosing rates would be ~1 μl/minute during water processing (for a system similar to the ISS WPA), requiring only approximately 20 ml/crew-year of concentrate. We identified and characterized the performance of three dosing systems: pressure-driven flow through a robust micro-capillary tube, a miniature peristaltic pump, and a multi-piston pump with integrated valving. We began to address several potential system reliability concerns including prevention or segregation of gas bubbles in the concentrate reservoirs as well as long-term materials compatibility and mechanical life.

Lance Dean Delzeit↗
DOE OSTI2025

Data-Driven Kinetic Reaction Networks for Separation Chemistry

Understanding complex, multistep chemical reactions at the molecular level is a major challenge whose solution would greatly benefit the design and optimization of numerous chemical processes. The separation of rare-earth (4f) and actinide (5f) elements is an example where improving our chemical understanding is important for designing and optimizing new chemistries, even with a limited number of observations. Here, in this work, we leverage data-driven artificial intelligence and machine-learning approaches to develop kinetic reaction networks that describe the liquid–liquid extraction mechanism of uranium using N,N-di-2-ethylhexyl-isobutyramide (DEHiBA). Specifically, we compare and contrast the properties of two classes of models: (1) purely data-driven models that are regularized using chemistry-agnostic, L1 regression and (2) chemistry-informed models that are regularized using relative reaction energies provided by quantum mechanical calculations. We observe that purely data-driven models are unbiased, simple, and accurate in their predictions of experimental measurements when provided with sufficient data but are difficult to fully constrain and interpret. In contrast, chemistry-informed models exhibit significantly improved chemical interpretability and consistency, providing a detailed description of the separation process while achieving high accuracy through ensemble averaging. Overall, the dominant species predicted to be extracted into the organic phase is UO 2 (NO 3 ) 2 (DEHiBA) 2 , agreeing with experimental slope analysis, thermodynamic modeling, EXAFS, and crystal structures. This work demonstrates that leveraging the fundamental structure of the problem can lead to efficient learning schemes that provide both accurate predictions and chemical insights at a low computational cost.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2023

Assessment of the Fluid Dynamics Boundary Condition in Ablating or Blowing Flows

Improved models of ablative thermal protection systems have enabled the treatment of materials and fluid behavior in a coupled manner. This paper reports a new approach to modeling the interface between fluid and material, with attention to the conservation of species mass flux and energy on the fluid side of the interface. The general equation is presented and is shown to recover the traditional uncoupled fluid/materials response interface. Including the chemical reaction terms on the CFD side of the interface makes the heat flux exchange independent of the thermodynamic reference state and, therefore, a measurable quantity. Doing so allows the material response solver to take as input the surface heat flux rather than a film coefficient. Removing the film coefficient approximation enables more direct solution of vehicle thermal response but requires consistency in the wall state. The mixing of the shock layer and pyrolysis gas is then computed with finite rate chemistry within the fluid solver. The boundary conditions described have been implemented in the DPLR v4.05.1 code. Char removal is captured using finite rate chemistry in DPLR’s gas surface interaction module. Aspects of coupling these solutions to material response are discussed.

Ablation↗
NASA NTRS2023

Assessment of the Fluid Dynamics Boundary Condition in Ablating or Blowing Flows

Improved models of ablative thermal protection systems have enabled the treatment of materials and fluid behavior in a coupled manner. This paper reports a new approach to modeling the interface between fluid and material, with attention to the conservation of species mass flux and energy on the fluid side of the interface. The general equation is presented and is shown to recover the traditional uncoupled fluid/materials response interface. Including the chemical reaction terms on the CFD side of the interface makes the heat flux exchange independent of the thermodynamic reference state and, therefore, a measurable quantity. Doing so allows the material response solver to take as input the surface heat flux rather than a film coefficient. Removing the film coefficient approximation enables more direct solution of vehicle thermal response but requires consistency in the wall state. The mixing of the shock layer and pyrolysis gas is then computed with finite rate chemistry within the fluid solver. The boundary conditions described have been implemented in the DPLR v4.05.1 code. Char removal is captured using finite rate chemistry in DPLR’s gas surface interaction module. Aspects of coupling these solutions to material response are discussed.

Ablation↗
DOE OSTI2025

Creating free standing covalent organic framework membranes by nanocrystal suturing in sol gel solutions

The sol-gel synthesis represents a versatile platform to fabricate ceramic inorganic membranes. However, it is still a grand challenge to push the boundary of sol-gel chemistry towards high-quality organic membrane construction. Herein, a facile and controlled nanocrystal suturing strategy in sol-gel solutions is developed to afford highly crystalline and free-standing covalent organic framework membranes. The key chemistry design lies in deploying tiny threads (1 mol% dual-NH 2 -tail linear polymer) to efficiently suture the highly charged covalent organic framework nanocrystals stabilized and confined in sol-gel solutions, creating a continuous and intact membrane surface. A subsequent treatment heals the sutured covalent organic framework nanocrystals, yielding a free-standing membrane with high crystallinity and ordered pores. The structure evolution and role of the thread linker are elucidated via operando spectroscopy and microscopy. The as-afforded covalent organic framework membranes demonstrate attractive proton transport performance in high temperature and anhydrous fuel cell applications.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Toward Sustainable Lithium Recovery: A Universal Hydrothermal Approach for Lithium Extraction

The rapid growth of lithium-ion battery (LIB) deployment presents critical challenges in sustainable end-of-life management and raw material recovery. Conventional pyrometallurgical and hydrometallurgical methods suffer from high energy demand, lithium loss, and complex wastewater treatment. This study established a universal, highly efficient, and sustainable hydrothermal route for lithium extraction and material recovery from various spent lithium-ion battery cathodes using 1,2,4,5-benzenetetracarboxylic acid (BTCA). The optimized process achieved over 99% lithium leaching efficiency for lithium iron phosphate (LFP) and LiNi x Mn y Co 1–x–y O 2 (NMC), with transition metal coleaching below 1%. It was also broadly applicable to lithium manganese oxide, lithium cobalt oxide, and black mass, achieving 98.5%, 98.95%, and 94.06% leaching efficiencies, respectively. The extracted lithium was directly converted into battery-grade lithium sources, while transition metals were recovered as oxides. Unreacted BTCA was efficiently regenerated and reused without degradation. Electrochemical evaluation confirmed that cathode materials synthesized with recovered lithium exhibit comparable performance to commercial products. Compared to conventional hydrometallurgy, the BTCA-based process increased revenue by over 40% and reduced greenhouse gas emissions by up to 39%. This closed-loop, chemistry-agnostic strategy offered a scalable and economically viable solution for industrial LIB recycling, enabling resource circularity and reducing dependency on primary critical materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Refinement of Pitting Factor Basis to Evaluate Minimum Nitrite Requirement in Dilute Waste Chemistries

Considering that chloride concentrations are an order of magnitude lower at SRS than the maximum chloride previously tested to evaluate pitting susceptibility of carbon steel, it has been proposed that the Pitting Factor methodology be refined to determine if a reduction in the minimum nitrite requirement is warranted in more dilute solutions and those with chloride concentrations more indicative of waste tank chemistries at SRS. Through the use of cyclic potentiodynamic polarization, the susceptibility of A537 carbon steel to pitting corrosion was evaluated. The Pitting Factor was shown to accurately predict pitting susceptibility throughout the chemistry envelope evaluated. In addition, it was shown that nitrite is not required for inhibition of pitting corrosion in tank conditions with chloride concentrations observed at SRS and up to 4 M nitrate. Based upon these findings, new control limits were proposed that removed the minimum nitrite requirement within the chemistry envelope evaluated up to 50 °C.

36 MATERIALS SCIENCE↗