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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Applied Aspects of the Study of Thermodynamic Parameters of Oil Disperse Systems

For intensification of oil refining without using secondary processes, thermodynamic parameters of gas condensate and residual fuel oil blends were calculated from experimental investigations involving inverse gas chromatography. Apparently, from thermodynamic parameters of gas condensate and residual fuel oil blend, it is possible to determine the optimal ratio of the components for increasing the yield of light fractions. It is likely that the new colloidal structure of the blend of the disperse system (residual fuel oil) with the homogeneous system (gas condensates) forms via formation of a semicolloidal system followed by restructurization due to intermolecular interaction and dissolution processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

An Eco-friendly Porous Poly(imide-ether)s for the Efficient Removal of Methylene Blue: Adsorption Kinetics, Isotherm, Thermodynamics and Reuse Performances

Poly(imide-ether)s (PIEs), which is porous in nature, was synthesized using aromatic diamines and dianhydrides via the solution polycondenzation reaction. In the process, PIEs was used as an adsorbent for the removal of basic dye [Methylene blue (MB)] from the aqueous solution. The structure and the thermal stability of PIEs were characterized by FT-IR, {sup 1}H-NMR, XRD and TG analysis, and the adsorption behaviour of the PIEs was confirmed using UV/Visible, FT-IR and SEM with EDX analysis. Batch adsorption experiments were carried out and their parameters (pH 6.95), initial MB concentration (200 mg/L), adsorbent dosage (50 mg), contact time (120 min) and temperature (28 °C) were optimized. The batch adsorption experimental data of the effect of contact time, initial MB concentration and temperature were evaluated using the adsorption kinetics (Pseudo-first order, Pseudo-second order, Elovich and Intra-particle diffusion kinetic), isotherm (Langmuir, Freundlich, Redlich–Peterson and Sips isotherms) and thermodynamic models respectively. In the study, adsorption of MB onto PIEs followed Pseudo-second kinetics and found to be the best fitting model based on the obtained experimental data. The homogeneity and heterogeneity surface nature of PIEs were elucidated with two and three isotherm parameters respectively. The adsorption thermodynamic study indicates that the adsorption of MB onto PIEs was endothermic and spontaneous in nature. The adsorbed PIEs solid waste was utilized to prepare the polymer composite, and its property was characterized. Graphical Abstract: .

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

A DFT Study on Structural, Electronic Mechanical and Thermodynamic Properties of 5f-Electron System BaAmO{sub 3}

The structural, electronic, mechanical and thermodynamic properties of the perovskite oxide BaAmO{sub 3} have been predicted using the full-potential linearized augmented plane wave (FP-LAPW) method. The equilibrium lattice constant, bulk modulus and pressure derivative were computed using different exchange correlations. The optimization of structure was carried out in ferromagnetic, anti-ferromagnetic and non-magnetic states, and the compound was found to be stable in the ferromagnetic state. A systematic study on the band structure and density of states was accomplished using generalized gradient approximation (GGA), Hubbard approximation (GGA + U) and modified Becke–Johnson exchange potential (mBJ),and the compound was found to have a half-metallic nature in all the approximations. The calculated total spin magnetic moment was found to be 5 μ{sub B} in all the approximations used. The second-order elastic constants, Young modulus, shear modulus, Poisson ratio and anisotropic factor have also been calculated. In order to have a complete understanding of BaAmO{sub 3}, the thermodynamic properties were studied in the pressure range of 0 to 40 GPa and the temperature range extending from 0 to 600 K.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Magnetic, Optoelectronic, and Thermodynamic Properties of Sr{sub 2}CrXO{sub 6} (X = La and Y): Half-Metallic and Ferromagnetic Behavior

The effects of spin polarization on the structure, magnetic, and optoelectronic properties of Cr-based series of double perovskites Sr{sub 2}CrXO{sub 6} (X = La and Y) have been studied by using the full-potential linearized augmented plane-wave method (FP-LAPW), based on the density functional theory (DFT) as implemented in the Wien2k code, within the generalized gradient approximation (GGA), GGA + U, and GGA plus Trans-Blaha-modified Becke–Johnson (TB-mBJ) as the exchange correlation. Our results show a similar half-metallic ferromagnetic ground state for both materials. From the electronic properties, it is found that Sr{sub 2}CrYO{sub 6} has a direct band gap at (Γ-Γ) direction and Sr{sub 2}CrLaO{sub 6} has an indirect band gap at (Γ-W) direction. Furthermore, we have computed the optic and thermodynamic properties which are investigated for the first time. Consequently, the magnetic, optoelectronic, and thermodynamic properties show these compounds are promising for high technological applications, namely spintronic materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

First Principle Mechanical and Thermodynamic Properties of Some TbX (X = S, Se) Compounds

The mechanical and thermodynamic results of some terbium chalcogenides, TbX (X = S, Se) compounds have been examined using full-potential linear augmented plane wave (FP-LAPW) method based on density functional theory. The local spin density approximation with Hubbard potential (LSDA+U) has been used for proper treatment of 4f-electrons of Tb. The magnetic moment of TbS and TbSe was calculated to be 5.44μ{sub B} and 5.57μ{sub B}, respectively. The ground state properties such as lattice parameter, bulk modulus, and pressure derivative of bulk modulus were obtained and found in good agreement with already available theory and experiment results. The mechanical properties such as Young modulus (E), shear modulus (G), Poisson ratio (υ), Cauchy pressure and B/G ratio were also predicted. Further, in thermodynamic properties, Debye temperatures (θ{sub D}), specific heats at constant volume(C{sub V}), thermal expansion co-efficient (α), and entropies (S) and their behavior with high temperature(0–1200 K) and pressure (0–50 GPa) were also predicted.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Bifurcation and Stability Analysis of the Equilibrium States in Thermodynamic Systems in a Small Vicinity of the Equilibrium Values of Parameters

The dynamic behavior of thermodynamic system, described by one order parameter and one control parameter, in a small neighborhood of ordinary and bifurcation equilibrium values of the system parameters is studied. Using the general methods of investigating the branching (bifurcations) of solutions for nonlinear equations, we performed an exhaustive analysis of the order parameter dependences on the control parameter in a small vicinity of the equilibrium values of parameters, including the stability analysis of the equilibrium states, and the asymptotic behavior of the order parameter dependences on the control parameter (bifurcation diagrams). The peculiarities of the transition to an unstable state of the system are discussed, and the estimates of the transition time to the unstable state in the neighborhood of ordinary and bifurcation equilibrium values of parameters are given. The influence of an external field on the dynamic behavior of thermodynamic system is analyzed, and the peculiarities of the system dynamic behavior are discussed near the ordinary and bifurcation equilibrium values of parameters in the presence of external field. The dynamic process of magnetization of a ferromagnet is discussed by using the general methods of bifurcation and stability analysis presented in the paper.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Thermodynamic Investigation of the Effect of Target Compositions and Conditions of Their Magnetron Sputtering on Phase Compositions of the Resulting Films

A thermodynamic investigation of plasmochemical processes taking place in a magnetron during sputtering of the targets consisting of indium and dysprosium ions is performed, which allowed identifying the feasibility of forming under the given conditions certain amounts of the chemical compounds In{sub 2}O{sub 3}, Dy{sub 2}O{sub 3}, DyInO{sub 3}. In the thermodynamic analysis of the equilibrium compositions during magnetron sputtering of the films, a universal TERRA software program is used.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Roles of Solvent in the Catalytic Hydrogen Release from Liquid Organic Hydrogen Carriers: Chemical, Thermodynamical and Technological Aspects

A Liquid Organic Hydrogen Carrier (LOHC) enables the storage and transport of hydrogen at ambient pressures and temperatures in a safe and convenient form using current infrastructure. However, it is challenging to directly compare reactivity and selectivity for hydrogen release, especially when comparing the catalytic efficiencies of neat LOHCs to highly diluted LOHCs in different solvents, reaction conditions, and catalysts. This work evaluates the role of solvents in catalysis and quantifies the energy efficiency of the overall process. The presence of solvent dilutes the volumetric density of available hydrogen, but may be necessary to achieve optimal catalysts stability, reactivity, and product selectivity. With respect to the reaction conditions as determined by thermodynamics, solvents with higher vapor pressures than that of the carrier can cause the erroneous impression of a more favorable reaction equilibrium. Concerning energy efficiency, solvents can result in increased energy demand for hydrogen release as the inert solvent must be heated to reaction temperatures required for release of H 2 from the LOHC. Further, this work recommends that investigations of catalyst reactivity should be carried out at different ratios of solvent to LOHC to understand how the reactivity changes and what the implications are for maximizing energy density and catalyst stability and reactivity. Investigations should also consider how these implications will affect the technical needs of applications intended for the LOHC system. Based on the results of this study, it is advised to focus research activities on LOHC systems with a gravimetric solvent content below about 50% as the thermodynamic disadvantages become very pronounced beyond this threshold.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Thermodynamics of Boron Removal from Silicon Using CaO-MgO-Al{sub 2}O{sub 3}-SiO{sub 2} Slags

Slag refining is one of few metallurgical methods for removal of boron from silicon. It is important to know the thermodynamic properties of boron in slags to understand the refining process. The relation of the distribution coefficient of boron to the activity of silica, partial pressure of oxygen, and capacity of slags for boron oxide was investigated. The link between these parameters explains why the distribution coefficient of boron does not change much with changing slag composition. In addition, the thermodynamic properties of dilute boron oxide in CaO-MgO-Al{sub 2}O{sub 3}-SiO{sub 2} slags was determined. The ratio of the activity coefficient of boron oxide and silica was found to be the most important parameter for understanding changes in the distribution coefficient of boron for different slags. Finally, the relation between the activity coefficient of boron oxide and slag structure was investigated. It was found that the structure can explain how the distribution coefficient of boron changes depending on slag composition.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Thermodynamic and Structural Study of the Copper-Aluminum System by the Electrochemical Method Using a Copper-Selective Beta″ Alumina Membrane

The liquid phase thermodynamics of mixing of the copper-aluminum binary system are investigated as a function of temperature and composition using the electrochemical potential difference method. A copper-selective beta″ alumina is used as a solid electrolyte, synthesized through ion exchange, sintering from base oxide powders, and the floating zone method of crystal growth. Measured thermodynamics of mixing data were used to inform short-range ordering in copper-aluminum melts through Darken’s factor for excess stability and Bhatia–Thornton structure factors, revealing a strong departure from ideality and pronounced ordering. Mixing properties were used to predict viscosity and self-diffusion coefficients. Features observed in calculated electronic entropy of mixing for copper-aluminum were compared with trends in viscosity, demonstrating the utility of electronic properties of mixing in the description of structure–properties in this liquid binary system.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Transient Behavior and Thermodynamics of Inclusions in Al-Ti-Deoxidized and Ca-Treated Steel

Ti-alloyed steels have severe nozzle clogging problems, which are detrimental to the steel production process. However, little research on the Al-Ti-Ca-O complex inclusion in molten steel has been carried out. Based on that, experiments with different calcium additions were carried out in an Al{sub 2}O{sub 3} crucible at 1873 K to investigate the variation of inclusions in Ti-bearing Al-killed steel in the current article. It was found that calcium treatment significantly influenced the morphology, composition distribution, and size of oxides in Ti-bearing Al-killed steel. Inclusions with a higher CaO or TiO{sub x} content were liquid at 1873 K (1600 °C), indicating that the inclusions in Ti-contained steel can be modified to liquid ones through the proper calcium treatment process. The appropriate amount of calcium should be added to the steel depending upon the aluminum and titanium contents. Thermodynamics of the inclusions in the Al-Ti-Ca-O molten steel system at high temperature and during the solidification process were comprehensively calculated, including all types of inclusions such as calcium oxide, aluminum oxide, titanium oxide, calcium aluminate, calcium titanate, and liquid inclusion. The thermodynamic calculations agree well with the experimental results and can precisely predict the formation of the inclusions in Al-Ti-Ca deoxidized steel.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Determination of Thermodynamic Properties of Si-B Alloys

This study establishes the thermodynamic properties of the Si-B binary alloy system. The electromotive force (emf) as a function of temperature (823 K to 923 K) was measured using solid-state electrochemical cells, represented as(−) Pt,Ar/{Si∥CaF_2∥} {Si−B(alloy)}/Ar,Pt(+) Using the experimental emf data obtained from the solid-state heterogeneous phase equilibrium, the activities of Si and B in Si-B alloys were calculated. The integral Gibbs energy of mixing (ΔG{sup M}) of alloys were calculated from the activity of Si and B. A large negative deviation from ideality was found for the integral Gibbs energy of mixing (ΔG{sup M}) of the binary Si-B system. From the activities of Si and B, the Gibbs energies of formation (ΔG{sub f}{sup 0}) of phases present were calculated. The ΔG{sub f}{sup 0} of SiB{sub 3}, the most thermodynamically stable phase, was calculated as − 13.13 ± 0.19 kJ/mole-atoms at 923 K. The heterogeneous phases and microstructure after the equilibrium study of the electrode were characterized using XRD, SEM, and EDS analyses.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Efficiency at Maximum Power of Dissipative Thermoelectric Generators: A Finite-time Thermodynamic Analysis

In this paper we analyze the thermodynamic efficiency expected for a fully dissipative thermoelectric generator (TEG) operating under stationary conditions at a finite rate. Although a finite-time thermodynamic analysis of TEGs has been aimed at since long time, no complete theory is available yet. The state of the art of theory is reviewed, and a simple expression for the maximum achievable efficiency of TEGs operating under fully irreversible conditions is obtained. This also sets a reference efficiency for forthcoming studies of nonstationary operation of TEGs.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Ab Initio Modeling on The Thermodynamic and Temperature-Dependent Elastic Properties of Subsystems of The FCC FeNiCoCr Medium Entropy Alloys (MEAs)

The stability, phonon spectra, thermodynamic, and temperature-dependent elasticity of subsystems of the FCC FeNiCoCr MEAs are systematically studied by the ab initio approach. Especially, the quasi-harmonic approximation (QHA) and the innovative Zentropy theory were utilized to predict the thermodynamic properties and elastic properties of FeNi, NiCo, FeNiCo, and FeNiCoCr MEAs with the consideration of magnetic transition. With the ensemble of the partition function based on the multiplicity of each magnetic configuration, the current work successfully reproduced the Curie temperature and the Schottky anomaly of heat capacity of these four MEAs purely based on the ab initio input. Meanwhile, the elastic properties of these alloys at finite temperatures are also successfully predicted with the consideration of magnetic transition. The overall results agree well with the available experimental data and CALPHAD prediction.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Thermodynamic assessment of the quaternary WTaCrV refractory high entropy alloy as a means to guide experimental approaches

The deployment of fusion energy poses challenges for materials in plasma facing components to withstand high temperatures and thermal gradients, particle implantation and neutron damage. The current material of choice is tungsten, although property degradation limits its consideration in future fusion reactors. Hence, materials with better resistance to harsh environments need to be developed for fusion energy to become a reality. High entropy alloys are being explored as potential candidates with some compositions showing good radiation resistance to defect cluster formation. One of these materials is the WTaCrV system, although only one composition has been tested under ion irradiation. In this work, we study the thermodynamic properties of the entire quaternary alloy composition range. Coupling first principles calculations, cluster expansion approaches, and Monte Carlo methods, we access the free energy functionals, short-range ordering as a function of temperature, and atomic configurations that can be compared to experimental observations. We use this data to inform experiments into compositions with higher propensity to form solid solutions, instead of phase separating. With this formalism we have developed thermodynamic database (TDB) files that can be used to plot quaternary phase diagrams.

Cluster Expansion↗
DOE OSTI2014

Molecular extended thermodynamics of rarefied polyatomic gases and wave velocities for increasing number of moments

Molecular extended thermodynamics of rarefied polyatomic gases is characterized by two hierarchies of equations for moments of a suitable distribution function in which the internal degrees of freedom of a molecule is taken into account. On the basis of physical relevance the truncation orders of the two hierarchies are proven to be not independent on each other, and the closure procedures based on the maximum entropy principle (MEP) and on the entropy principle (EP) are proven to be equivalent. The characteristic velocities of the emerging hyperbolic system of differential equations are compared to those obtained for monatomic gases and the lower bound estimate for the maximum equilibrium characteristic velocity established for monatomic gases (characterized by only one hierarchy for moments with truncation order of moments N) by Boillat and Ruggeri (1997) (λ{sub (N)}{sup E,max})/(c{sub 0}) ⩾√(6/5 (N−1/2 )),(c{sub 0}=√(5/3 k/m T)) is proven to hold also for rarefied polyatomic gases independently from the degrees of freedom of a molecule. -- Highlights: •Molecular extended thermodynamics of rarefied polyatomic gases is studied. •The relation between two hierarchies of equations for moments is derived. •The equivalence of maximum entropy principle and entropy principle is proven. •The characteristic velocities are compared to those of monatomic gases. •The lower bound of the maximum characteristic velocity is estimated.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Higher order corrected thermodynamics and statistics of Kerr–Newman–Gödel black hole

In this paper, we consider the rotating charged Gödel black hole and study the effect of the higher order corrections of the entropy on the thermodynamics and statistics quantities of the Kerr–Newman–Gödel black hole. The leading order correction is logarithmic while higher-order terms are proportional to the inverse of the area of the black hole. We obtain modified thermodynamics and statistics and find that correction terms are important in the stability of the black hole.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗