Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “THERMODYNAMICS”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Thermodynamics of Yukawa fluids near the one-component-plasma limit

Thermodynamics of weakly screened (near the one-component-plasma limit) Yukawa fluids in two and three dimensions is analyzed in detail. It is shown that the thermal component of the excess internal energy of these fluids, when expressed in terms of the properly normalized coupling strength, exhibits the scaling pertinent to the corresponding one-component-plasma limit (the scalings differ considerably between the two- and three-dimensional situations). This provides us with a simple and accurate practical tool to estimate thermodynamic properties of weakly screened Yukawa fluids. Particular attention is paid to the two-dimensional fluids, for which several important thermodynamic quantities are calculated to illustrate the application of the approach.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Thermodynamics of amyloid formation and the role of intersheet interactions

The self-assembly of proteins into β-sheet-rich amyloid fibrils has been observed to occur with sigmoidal kinetics, indicating that the system initially is trapped in a metastable state. Here, we use a minimal lattice-based model to explore the thermodynamic forces driving amyloid formation in a finite canonical (NVT) system. By means of generalized-ensemble Monte Carlo techniques and a semi-analytical method, the thermodynamic properties of this model are investigated for different sets of intersheet interaction parameters. When the interactions support lateral growth into multi-layered fibrillar structures, an evaporation/condensation transition is observed, between a supersaturated solution state and a thermodynamically distinct state where small and large fibril-like species exist in equilibrium. Intermediate-size aggregates are statistically suppressed. These properties do not hold if aggregate growth is one-dimensional.

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

Quantitative Predictive Theories through Integrating Quantum, Statistical, Equilibrium, and Nonequilibrium Thermodynamics

Today's thermodynamics is largely based on the combined law for equilibrium systems and statistical mechanics derived by Gibbs in 1873 and 1901, respectively, while irreversible thermodynamics for nonequilibrium systems resides essentially on the Onsager Theorem as a separate branch of thermodynamics developed in 1930s. Between them, quantum mechanics was invented and was quantitatively solved in terms of density functional theory (DFT) in 1960s. Furthermore, these three scientific domains operate based on different principles and are very much separated from each other. In analogy to the parable of the blind men and the elephant articulated by Perdew, they individually represent different portions of a complex system and thus are incomplete by themselves alone, resulting in the lack of quantitative agreement between their predictions and experimental observations. Over the last two decades, the author's group has developed a multiscale entropy approach (recently termed as zentropy theory) that integrates DFT-based quantum mechanics and Gibbs statistical mechanics and is capable of accurately predicting entropy and free energy of complex systems. Furthermore, in combination with the combined law for nonequilibrium systems developed by Hillert, the author developed the theory of cross phenomena beyond the phenomenological Onsager Theorem. The zentropy theory and theory of cross phenomena jointly provide quantitative predictive theories for systems from electronic to any observable scales as reviewed in the present work.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Transport phenomena in electrolyte solutions: Nonequilibrium thermodynamics and statistical mechanics

The theory of transport phenomena in multicomponent electrolyte solutions is presented here through the integration of continuum mechanics, electromagnetism, and nonequilibrium thermodynamics. The governing equations of irreversible thermodynamics, including balance laws, Maxwell's equations, internal entropy production, and linear laws relating the thermodynamic forces and fluxes, are derived. Green–Kubo relations for the transport coefficients connecting electrochemical potential gradients and diffusive fluxes are obtained in terms of the flux–flux time correlations. Furthermore, the relationship between the derived transport coefficients and those of the Stefan–Maxwell and infinitely dilute frameworks are presented, and the connection between the transport matrix and experimentally measurable quantities is described. To exemplify the application of the derived Green–Kubo relations in molecular simulations, the matrix of transport coefficients for lithium and chloride ions in dimethyl sulfoxide is computed using classical molecular dynamics and compared with experimental measurements.

42 ENGINEERING↗
DOE OSTI2021

Evaluation and Applications of Multi-Instrument Boundary-Layer Thermodynamic Retrievals

Recent reports have highlighted the need for improved observations of the atmosphere boundary layer. In this study, we explore the combination of ground-based active and passive remote sensors deployed for thermodynamic profiling to analyze various boundary-layer observation strategies. Optimal-estimation retrievals of thermodynamic profiles from Atmospheric Emitted Radiance Interferometer (AERI) observed spectral radiance are compared with and without the addition of active sensor observations from a May–June 2017 observation period at the Atmospheric Radiation Measurement Southern Great Plains site. In all, three separate thermodynamic retrievals are considered here: retrievals including AERI data only, retrievals including AERI data and Vaisala water vapour differential-absorption lidar data, and retrievals including AERI data and Raman lidar data. First, the three retrievals are compared to each other and to reference radiosonde data over the full observation period to obtain a bulk understanding of their differences and characterize the impact of clouds on these retrieved profiles. These analyses show that the most significant differences are in the water vapour field, where the active sensors are better able to represent the moisture gradient in the entrainment zone near the boundary-layer top. Furthermore, we also explore how differences in retrievals may affect results of applied analyses including land–atmosphere coupling, convection indices, and severe storm environmental characterization. Overall, adding active sensors to the optimal-estimation retrieval shows some added information, particularly in the moisture field. Given the costs of such platforms, the value of that added information must be weighed for the application at hand.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Ab Initio Investigation on Electronic, Magnetic, Mechanical, and Thermodynamic Properties of AMO{sub 3} (A = Eu, M = Ga, In) Perovskites

The structural, electronic, magnetic, elastic, and thermodynamic properties of cubic AMO{sub 3} perovskites (A = Eu, M = Ga, In) have been successfully studied within density functional theory using full-potential linearized augmented plane wave (FP-LAPW). The structural study reveals that both the compounds are stable in ferromagnetic states. The GGA + U calculated spin-polarized electronic band and density of states present the half-metallic nature of both the compounds. The magnetic moments calculated with different approximations were found to be approximately 6 μ{sub B} for EuGaO{sub 3} and approximately 7 μ{sub B} for EuInO{sub 3}. From elastic calculation, the three independent elastic constants (C{sub 11}, C{sub 12}, C{sub 44}) have been acquired to yield the mechanical properties like Young modulus (Y ), shear modulus (G), Poisson ratio (ν), and anisotropic factor (A). The calculated values of B/G show that both the compounds are ductile in nature. The thermodynamic study was also accomplished by exploring the thermodynamic parameters like specific heat, heat capacity, thermal expansion, Grüneisen parameter, Debye temperature, etc. within the temperature range 0 to 900 K and pressure range 0 to 50 GPa.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2013

Thermodynamic Model for the Solubility of NdF 3 (cr) in the Na + -NH 4 + – Nd 3+ –F - –H 2 O System at 25 °C

The objectives of this study were to develop a reliable thermodynamic model for the Nd-F system based on critical review and experimental studies. The SIT model was used to convert concentration constants reported in the literature to constants at zero ionic strengths for cross comparison and selection of reliable values. The critically evaluated thermodynamic constants for the formation of NdF 2+ and NdF 2+ were then used to interpret the extensive NdF3(cr) solubility data in NaF and NH 4 F solutions, ranging in concentrations from extremely low values to as high as 1.0 mol.kg-1, equilibrated for different periods ranging up to as long as 72 days. These efforts have resulted in log β n 0 for the reaction [Nd 3+ + nF - = NdF n</ 3-n ] of (3.81 ± 0.10), (5.89 ± 0.77), and <12.48 for n of 1 through 3, respectively. The log10 K sp 0 for the solubility of NdF 3 (cr) (NdF3(cr) = Nd 3+ + 3F - ) was determined to be -(20.49 ± 0.37). Because 1) Nd is an excellent analog for trivalent actinides -- An(III) (e.i., Pu(III), Am(III), and Cm(III)) -- and 2) the available data for the An(III)-F system, especially the solubility products of AnF 3 (cr), are of extremely poor quality, the critical literature review in combination with the experimental Nd-F system data have been used to assign thermodynamic constants for the An(III)-F reactions until good quality specific data for them becomes available.

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

A Thermodynamic Model for ZrO 2 (am) Solubility at 25 °C in the Ca 2+ –Na + –H + –Cl - –OH - –H 2 O System: A Critical Review

Zirconium is an important element in the nuclear fuel cycle. Thermodynamic data and models to reliably predict Zr-OH system behavior in various conditions including high ionic strengths are required and currently are unavailable. Most available experimental data are rather old, obtained using inadequate methodologies, and provide equilibrium constant values that differ by many orders of magnitude. Previous reviews have recommended values based on available data. These reviews used all of the available data, including poor quality data, in a global fit to determine these values. This has resulted in recommended thermodynamic models with a large number of polynuclear species and a number of mononuclear species with values of thermodynamic constants for the solubility product of ZrO 2 (am) and Zr-OH hydrolysis constants that are many orders of magnitude different than those for the reliable analogous Hf reactions. In this critical review, we have evaluated the quality of the available data, selected only those data that are of high quality, and reinterpreted all of the high quality data using SIT and Pitzer models for applications to high ionic strength solutions. Herein for 25°C we 1) present formation constant values for ZrOH 3+ , Zr(OH) 2+ 2 , Zr(OH) 4 (aq), Zr(OH) 5 - , and Zr(OH) 6 2- , and the solubility product for ZrO 2 (am) which are consistent with the Hf system, 2) report a revised value for the formation of Ca 3 Zr(OH) 6 4+ , 3) show that several hypothetical polynuclear species (Zr 3 (OH) 9 3+ , Zr 4 (OH) 15 + , and Zr 4 (OH) 16 (aq)) proposed in previous reviews are not needed, and 4) show that polynuclear species (Zr 3 (OH) 4 8+ and Zr 4 (OH) 8 8+ ) are not important in a very extensive H + concentration range (0.1 to 10 -15.4 mol·kg -1 ). Our review has also resulted in SIT and Pitzer ion-interaction parameters applicable to as high ionic strength solutions as 5.6 mol·kg -1 in NaCl, 2.11 mol·kg -1 in CaCl 2 , and 23.5 mol·kg -1 in NaOH.

solubility, ZrO2(am), solubility product, thermody↗
DOE OSTI2018

The Integration of Plant Sample Analysis, Laboratory Studies, and Thermodynamic Modeling to Predict Slag-Matte Equilibria in Nickel Sulfide Converting

The Kalgoorlie Nickel Smelter (KNS) produces low Fe, low Cu nickel matte in its Peirce–Smith converter operations. To inform process development in the plant, new fundamental data are required on the effect of CaO in slag on the distribution of arsenic between slag and matte. A combination of plant sample analysis, high-temperature laboratory experiments, and thermodynamic modeling was carried out to identify process conditions in the converter and to investigate the effect of slag composition on the chemical behavior of the system. The high-temperature experiments involved re-equilibration of industrial matte-slag-lime samples at 1498 K (1225 °C) and P(SO{sub 2}) = 0.12 atm on a magnetite/quartz substrate, rapid quenching in water, and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA) and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). A private thermodynamic database for the Ca-Cu-Fe-Mg-Ni-O-S-Si-(As) system was used together with the FactSage software package to assist in the analysis. Thermodynamic predictions combined with plant sample characterization and the present experimental data provide a quantitative basis for the analysis of the effect of CaO fluxing on the slag-matte thermochemistry during nickel sulfide converting, in particular on the spinel liquidus and the distribution of elements between slag and matte as a function of CaO addition.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Critical Evaluation and Thermodynamic Optimization of the Li{sub 2}O-Al{sub 2}O{sub 3} and Li{sub 2}O-MgO-Al{sub 2}O{sub 3} Systems

The thermodynamic and phase diagram data of the Li{sub 2}O-Al{sub 2}O{sub 3} and Li{sub 2}O-MgO-Al{sub 2}O{sub 3} systems were critically evaluated and optimized to obtain a set of consistent Gibbs energy functions for all phases in the systems. The LiAl{sub 5}O{sub 8}-MgAl{sub 2}O{sub 4} spinel solid solution was modeled with the two-sublattice compound energy formalism by considering the cation distribution between the tetrahedral and octahedral sites and excess vacancy in octahedral sites. The liquid phase and monoxide solid solution were also described using the modified quasichemical model with pair approximation and the Bragg–Williams random mixing model, respectively. The thermodynamic models with optimized model parameters enable the reproduction of all reliable thermodynamic and phase diagram as well as spinel structural data in the system.

36 MATERIALS SCIENCE↗
DOE OSTI2015

The second law of thermodynamics under unitary evolution and external operations

The von Neumann entropy cannot represent the thermodynamic entropy of equilibrium pure states in isolated quantum systems. The diagonal entropy, which is the Shannon entropy in the energy eigenbasis at each instant of time, is a natural generalization of the von Neumann entropy and applicable to equilibrium pure states. We show that the diagonal entropy is consistent with the second law of thermodynamics upon arbitrary external unitary operations. In terms of the diagonal entropy, thermodynamic irreversibility follows from the facts that quantum trajectories under unitary evolution are restricted by the Hamiltonian dynamics and that the external operation is performed without reference to the microscopic state of the system.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Bounded energy exchange as an alternative to the third law of thermodynamics

This paper introduces a postulate explicitly forbidding the extraction of an infinite amount of energy from a thermodynamic system. It also introduces the assumption that no measuring equipment is capable of detecting arbitrarily small energy exchanges. The Kelvin formulation of the second law is reinterpreted accordingly. Then statements related to both the unattainability version and the entropic version of the third law are derived. The value of any common thermodynamic potential of a one-component system at absolute zero of temperature is ascertained if some assumptions with regard to the state space can be made. The point of view is the phenomenological, macroscopic and non-statistical one of classical thermodynamics.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

A thermodynamic cycle for the solar cell

A solar cell is a heat engine, but textbook treatments are not wholly satisfactory from a thermodynamic standpoint, since they present solar cells as directly converting the energy of light into electricity, and the current in the circuit as maintained by an electrostatic potential. Here we propose a thermodynamic cycle in which the gas of electrons in the ρ phase serves as the working substance. The interface between the ρ and n phases acts as a self-oscillating piston that modulates the absorption of heat from the photons so that it may perform a net positive work during a complete cycle of its motion, in accordance with the laws of thermodynamics. We draw a simple hydrodynamical analogy between this model and the “putt-putt” engine of toy boats, in which the interface between the water’s liquid and gas phases serves as the piston. We point out some testable consequences of this model.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Thermodynamic and kinetic characterization of hydroxyethylamine β-secretase-1 inhibitors

Highlights: •Kinetic and thermodynamic characterization of 10 hydroxyethylamine BACE-1 inhibitors. •Equilibrium binding of inhibitors was enthalpy driven for BACE-1. •Negative entropy of binding was observed towards BACE-1, but not Cathepsin-D. •Structural analysis demonstrates ligand binding induces a major conformational change. •Structural analysis and SPR analysis corroborate induced fit and negative entropy of binding. -- Abstract: Alzheimer’s disease (AD) is a devastating neurodegenerative disease affecting millions of people. β-Secretase-1 (BACE-1), an enzyme involved in the processing of the amyloid precursor protein (APP) to form Aβ, is a well validated target for AD. Herein, the authors characterize 10 randomly selected hydroxyethylamine (HEA) BACE-1 inhibitors in terms of their association and dissociation rate constants and thermodynamics of binding using surface plasmon resonance (SPR). Rate constants of association (k{sub a}) measured at 25 °C ranged from a low of 2.42 × 10{sup 4} M{sup −1} s{sup −1} to the highest value of 8.3 × 10{sup 5} M{sup −1} s{sup −1}. Rate constants of dissociation (k{sub d}) ranged from 1.09 × 10{sup −4} s{sup −1} (corresponding to a residence time of close to three hours), to the fastest of 0.028 s{sup −1}. Three compounds were selected for further thermodynamic analysis where it was shown that equilibrium binding was enthalpy driven while unfavorable entropy of binding was observed. Structural analysis revealed that upon ligand binding, the BACE-1flap folds down over the bound ligand causing an induced fit. The maximal difference between alpha carbon positions in the open and closed conformations of the flap was over 5 Å. Thus the negative entropy of binding determined using SPR analysis was consistent with an induced fit observed by structural analysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Crystal structure and thermodynamic dissection of chitin oligosaccharide binding to the LysM module of chitinase-A from Pteris ryukyuensis

Highlights: • Crystal structure of a LysM module from Pteris ryukyuensis chitinase-A (PrLysM2) was determined at a resolution of 1.8 Å. • LysM module recognizes chitin oligosaccharides in a shallow groove on the molecule. • Thermodynamic dissection of the binding energetics of (GlcNAc){sub 6} to PrLysM2 was carried out. • The binding site comprises of five sugar-binding subsites. We determined the crystal structure of a LysM module from Pteris ryukyuensis chitinase-A (PrLysM2) at a resolution of 1.8 Å. Structural and binding analysis of PrLysM2 indicated that this module recognizes chitin oligosaccharides in a shallow groove comprised of five sugar-binding subsites on one side of the molecule. The free energy changes (ΔG{sub r}°) for binding of (GlcNAc){sub 6}, (GlcNAc){sub 5}, and (GlcNAc){sub 4} to PrLysM2 were determined to be −5.4, −5,4 and −4.6 kcal mol{sup −1}, respectively, by ITC. Thermodynamic dissection of the binding energetics of (GlcNAc){sub 6} revealed that the driving force is the enthalpy change (ΔH{sub r}° = −11.7 ± 0.2 kcal/mol) and the solvation entropy change (−TΔS{sub solv}° = −5.9 ± 0.6 kcal/mol). This is the first description of thermodynamic signatures of a chitin oligosaccharide binding to a LysM module.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Thermodynamically consistent algorithms for models of incompressible multiphase polymer solutions with a variable mobility

Here we present a general strategy for developing structure and property preserving numerical algorithms for thermodynamically consistent models of incompressible multiphase polymer solutions with a variable mobility. We first present a formalism to derive thermodynamically consistent, incompressible, multiphase polymer models. Then, we develop the general strategy, known as the supplementary variable method, to devise thermodynamically consistent numerical approximations to the models. We illustrate the numerical strategy using newly developed models of incompressible diblock copolymer solutions coupled with an electric and a magnetic field, respectively. Mesh refinement is conducted to verify convergence rates of the developed schemes. Some numerical examples are given to exhibit underlying dynamics absent from and driven by the external fields, respectively, highlighting differences between models with the variable and constant mobilities.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Some comments on thermodynamic consistency for equilibrium mixture equations of state

We investigate sufficient conditions for thermodynamic consistency for equilibrium mixtures. Such models assume that the mass fraction average of the material component equations of state, when closed by a suitable equilibrium condition, provide a composite equation of state for the mixture. Here, we show that the two common equilibrium models of component pressure/temperature equilibrium and volume/temperature equilibrium (Dalton, 1808) define thermodynamically consistent mixture equations of state and that other equilibrium conditions can be thermodynamically consistent provided appropriate values are used for the mixture specific entropy and pressure.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Thermodynamics and kinetics of solution combustion synthesis: Ni(NO 3 ) 2 + fuels systems

Solution combustion synthesis (SCS) utilizes exothermic self-propagating reactions to prepare nanoscale materials that can be used widely in energy, electronics, and biomedical technologies and other applications. SCS is a specific variety of a more general combustion synthesis (CS) method. Investigations of the thermodynamics, kinetics, and the mechanisms of SCS reactions, are not as well studied as the other CS processes. This work reports on a systematic study of the thermodynamics and kinetics of SCS reactions involving Ni(NO 3 ) 2 , an oxidizer, and either glycine (C 2 H 5 NO 2 ) or hexamethylenetetramine (HMT, C 6 H 12 N 4 ) as fuels. A thermodynamic modeling approach, based on the Gibbs free energy minimization principle, is applied to the simultaneous calculations of the adiabatic temperatures and compositions of the equilibrium products. Our calculations reveal the influence of fuel-to-oxidizer ratio, amount of water, and the oxygen in air on the combustion temperature under adiabatic conditions and the composition of the resulting products. We have, in turn, measured the combustion temperature and phase composition of products and compared them with the calculations. Variations of drying times for the solutions yield precursor gels with varying water contents. This approach enables the manipulation of combustion parameters and confirms the use of calculated activation energies for reactions using the Merzhanov-Khaikin method. Here, the results show that SCS reactions in fuel-lean solutions producing NiO have higher activation energy in contrast to reactions with fuel-rich solutions that form Ni. Reduction of activation energies due to the increase in the fuel-to-oxidizer ratio could be related to the observed change of the rate-limiting stages of the endothermic decomposition of the individual reactants to the exothermic decomposition of coordinate compounds formed between the reactants.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗