Predictions of titanium alloy properties using thermodynamic modeling tools
Zhang, F.; Xie, F.-Y.; Chen, S.-L.; Chang, Y. A.; Furrer, D.; Venkatesh, V.
2005-12-01
Thermodynamic modeling tools have become essential in understanding the effect of alloy chemistry on the final microstructure of a material. Implementation of such tools to improve titanium processing via parameter optimization has resulted in significant cost savings through the elimination of shop/laboratory trials and tests. In this study, a thermodynamic modeling tool developed at CompuTherm, LLC, is being used to predict β transus, phase proportions, phase chemistries, partitioning coefficients, and phase boundaries of multicomponent titanium alloys. This modeling tool includes Pandat, software for multicomponent phase equilibrium calculations, and PanTitanium, a thermodynamic database for titanium alloys. Model predictions are compared with experimental results for one α-β alloy (Ti-64) and two near-β alloys (Ti-17 and Ti-10-2-3). The alloying elements, especially the interstitial elements O, N, H, and C, have been shown to have a significant effect on the β transus temperature, and are discussed in more detail herein.
Energy Technology Data Exchange (ETDEWEB)
Hagemann, Sven; Schoenwiese, Dagmar; Scharge, Tina
2015-07-15
The report on tools and data for the geochemical modeling covers the following issues: experimental methods and theoretical models, design of a thermodynamic model for reduced sulfur species, thermodynamic models for background salts, tools for the uncertainty and sensitivity analyses of geochemical equilibrium modeling.
Directory of Open Access Journals (Sweden)
Pablo Araujo Granda
2016-01-01
Full Text Available Modelling cellular metabolism is a strategic factor in investigating microbial behaviour and interactions, especially for bio-technological processes. A key factor for modelling microbial activity is the calculation of nutrient amounts and products generated as a result of the microbial metabolism. Representing metabolic pathways through balanced reactions is a complex and time-consuming task for biologists, ecologists, modellers and engineers. A new computational tool to represent microbial pathways through microbial metabolic reactions (MMRs using the approach of the Thermodynamic Electron Equivalents Model has been designed and implemented in the open-access framework NetLogo. This computational tool, called MbT-Tool (Metabolism based on Thermodynamics can write MMRs for different microbial functional groups, such as aerobic heterotrophs, nitrifiers, denitrifiers, methanogens, sulphate reducers, sulphide oxidizers and fermenters. The MbT-Tool's code contains eighteen organic and twenty inorganic reduction-half-reactions, four N-sources (NH4+, NO3−, NO2−, N2 to biomass synthesis and twenty-four microbial empirical formulas, one of which can be determined by the user (CnHaObNc. MbT-Tool is an open-source program capable of writing MMRs based on thermodynamic concepts, which are applicable in a wide range of academic research interested in designing, optimizing and modelling microbial activity without any extensive chemical, microbiological and programing experience.
Energy Technology Data Exchange (ETDEWEB)
PIERSON KL; MEINERT FL
2012-01-26
Two notable modeling efforts within the Hanford Tank Waste Operations Simulator (HTWOS) are currently underway to (1) increase the robustness of the underlying chemistry approximations through the development and implementation of an aqueous thermodynamic model, and (2) add enhanced planning capabilities to the HTWOS model through development and incorporation of the lifecycle cost model (LCM). Since even seemingly small changes in apparent waste composition or treatment parameters can result in large changes in quantities of high-level waste (HLW) and low-activity waste (LAW) glass, mission duration or lifecycle cost, a solubility model that more accurately depicts the phases and concentrations of constituents in tank waste is required. The LCM enables evaluation of the interactions of proposed changes on lifecycle mission costs, which is critical for decision makers.
Domańska, Urszula; Zawadzki, Maciej; Paduszyński, Kamil; Królikowski, Marek
2012-07-19
This contribution reports a recapitulation of our experimental and modeling study on thermodynamic behavior of binary systems containing N-alkylisoquinolinium ionic liquids (ILs) based on bis(trifluoromethylsulfonyl)imide anion, [CniQuin][NTf2] (n = 4,6,8). In particular, we report isothermal vapor-liquid equilibrium (VLE) phase diagrams and molar excess enthalpies of mixing (H(E)) for binary mixtures of [C8iQuin][NTf2] IL with various organic solutes including benzene, toluene, thiophene, pyridine, and butan-1-ol. The measured VLE data represented simple homozeotropic behavior with either negative or positive deviations from ideality, depending on polarity of the solute, temperature, and mole fraction of IL. In turn, the obtained data on H(E) were negative and positive for the mixtures containing aromatic hydrocarbons or thiophene and butan-1-ol, respectively, in the whole range of IL's concentration. All of the measured and some previously published data regarding phase behavior of [C8iQuin][NTf2] IL were analyzed and successfully described in terms of perturbed-chain statistical associating fluid theory (PC-SAFT). The methodology used in this work was described by us previously. In general, the proposed modeling results in VLE diagrams, which are in excellent agreement with experimental data. In the case of H(E), the results obtained are good as well but not so satisfactory such as those for VLE. Nevertheless, they seem to be very promising if one take into account the simplicity of the utilized molecular model against significant complexity of IL-based systems. Thus, we concluded that PC-SAFT equation of state can be viewed as a powerful and robust tool for modeling of systems involving ILs.
Ch. 33 Modeling: Computational Thermodynamics
International Nuclear Information System (INIS)
Besmann, Theodore M.
2012-01-01
This chapter considers methods and techniques for computational modeling for nuclear materials with a focus on fuels. The basic concepts for chemical thermodynamics are described and various current models for complex crystalline and liquid phases are illustrated. Also included are descriptions of available databases for use in chemical thermodynamic studies and commercial codes for performing complex equilibrium calculations.
Ghiorso, M. S.
2013-12-01
Internally consistent thermodynamic databases are critical resources that facilitate the calculation of heterogeneous phase equilibria and thereby support geochemical, petrological, and geodynamical modeling. These 'databases' are actually derived data/model systems that depend on a diverse suite of physical property measurements, calorimetric data, and experimental phase equilibrium brackets. In addition, such databases are calibrated with the adoption of various models for extrapolation of heat capacities and volumetric equations of state to elevated temperature and pressure conditions. Finally, these databases require specification of thermochemical models for the mixing properties of solid, liquid, and fluid solutions, which are often rooted in physical theory and, in turn, depend on additional experimental observations. The process of 'calibrating' a thermochemical database involves considerable effort and an extensive computational infrastructure. Because of these complexities, the community tends to rely on a small number of thermochemical databases, generated by a few researchers; these databases often have limited longevity and are universally difficult to maintain. ThermoFit is a software framework and user interface whose aim is to provide a modeling environment that facilitates creation, maintenance and distribution of thermodynamic data/model collections. Underlying ThermoFit are data archives of fundamental physical property, calorimetric, crystallographic, and phase equilibrium constraints that provide the essential experimental information from which thermodynamic databases are traditionally calibrated. ThermoFit standardizes schema for accessing these data archives and provides web services for data mining these collections. Beyond simple data management and interoperability, ThermoFit provides a collection of visualization and software modeling tools that streamline the model/database generation process. Most notably, ThermoFit facilitates the
Integrating Computational Science Tools into a Thermodynamics Course
Vieira, Camilo; Magana, Alejandra J.; García, R. Edwin; Jana, Aniruddha; Krafcik, Matthew
2018-01-01
Computational tools and methods have permeated multiple science and engineering disciplines, because they enable scientists and engineers to process large amounts of data, represent abstract phenomena, and to model and simulate complex concepts. In order to prepare future engineers with the ability to use computational tools in the context of their disciplines, some universities have started to integrate these tools within core courses. This paper evaluates the effect of introducing three computational modules within a thermodynamics course on student disciplinary learning and self-beliefs about computation. The results suggest that using worked examples paired to computer simulations to implement these modules have a positive effect on (1) student disciplinary learning, (2) student perceived ability to do scientific computing, and (3) student perceived ability to do computer programming. These effects were identified regardless of the students' prior experiences with computer programming.
Modeling the thermodynamics of QCD
Energy Technology Data Exchange (ETDEWEB)
Hell, Thomas
2010-07-26
Strongly interacting (QCD) matter is expected to exhibit a multifaceted phase structure: a hadron gas at low temperatures, a quark-gluon plasma at very high temperatures, nuclear matter in the low-temperature and high-density region, color superconductors at asymptotically high densities. Most of the conjectured phases cannot yet be scrutinized by experiments. Much of the present picture - particularly concerning the intermediate temperature and density area of the phase diagram of QCD matter - is based on model calculations. Further insights come from Lattice-QCD computations. The present thesis elaborates a nonlocal covariant extension of the Nambu and Jona-Lasinio (NJL) model with built-in constraints from the running coupling of QCD at high-momentum and instanton physics at low-momentum scales. We present this model for two and three quark flavors (in the latter case paying particular attention to the axial anomaly). At finite temperatures and densities, gluon dynamics is incorporated through a gluonic background field, expressed in terms of the Polyakov loop (P). The thermodynamics of this nonlocal PNJL model accounts for both chiral and deconfinement transitions. We obtain results in mean-field approximation and beyond, including additional pionic and kaonic contributions to the chiral condensate, the pressure and other thermodynamic quantities. Finally, the nonlocal PNJL model is applied to the finite-density region of the QCD phase diagram; for three quark flavors we investigate, in particular, the dependence of the critical point appearing in the models on the axial anomaly. The thesis closes with a derivation of the nonlocal PNJL model from first principles of QCD. (orig.)
Thermodynamically Feasible Kinetic Models of Reaction Networks
Ederer, Michael; Gilles, Ernst Dieter
2007-01-01
The dynamics of biological reaction networks are strongly constrained by thermodynamics. An holistic understanding of their behavior and regulation requires mathematical models that observe these constraints. However, kinetic models may easily violate the constraints imposed by the principle of detailed balance, if no special care is taken. Detailed balance demands that in thermodynamic equilibrium all fluxes vanish. We introduce a thermodynamic-kinetic modeling (TKM) formalism that adapts th...
Thermodynamic modeling of the Hf-N system
Directory of Open Access Journals (Sweden)
Pang M.
2018-01-01
Full Text Available Hf-N based alloys have been widely used and studied in the fields of electronic devices and cutting tools industry. A thermodynamic description of this system is essential for further materials development. By means of CALPHAD method, a thermodynamic modeling of the Hf-N system was carried out based on the available phase diagram data as well as thermodynamic property data. The Fcc phase is modeled as (Hf, Va1(N, Va1 to cover the composition range since the solubility of nitrogen in Fcc phase is reported up to about 52 at.%. A set of self-consistent thermodynamic parameters for the Hf-N system has been obtained. The computed phase diagrams and thermodynamic quantities using the present parameters agree well with the experimental data.
Thermodynamic modeling of complex systems
DEFF Research Database (Denmark)
Liang, Xiaodong
. Contrary to earlier theories, the oil is not only present on the surface, but also in great volumes both in the water column and on the seafloor, which indicates that we do not know enough about how oil behaves in water and interacts with it. Sonar detection is one of the most important and necessary...... after an oil spill. Engineering thermodynamics could be applied in the state-of-the-art sonar products through advanced artificial technology, if the speed of sound, solubility and density of oil-seawater systems could be satisfactorily modelled. The addition of methanol or glycols into unprocessed well...... streams during subsea pipelines is necessary to inhibit gas hydrate formation, and the offshore reservoirs often mean complicated temperature and pressure conditions. Accurate description of the phase behavior and thermalphysical properties of complex systems containing petroleum fluids and polar...
Yilmaz, L Safak; Parnerkar, Shreyas; Noguera, Daniel R
2011-02-01
Mathematical models of RNA-targeted fluorescence in situ hybridization (FISH) for perfectly matched and mismatched probe/target pairs are organized and automated in web-based mathFISH (http://mathfish.cee.wisc.edu). Offering the users up-to-date knowledge of hybridization thermodynamics within a theoretical framework, mathFISH is expected to maximize the probability of success during oligonucleotide probe design.
ms2: A molecular simulation tool for thermodynamic properties
Deublein, Stephan; Eckl, Bernhard; Stoll, Jürgen; Lishchuk, Sergey V.; Guevara-Carrion, Gabriela; Glass, Colin W.; Merker, Thorsten; Bernreuther, Martin; Hasse, Hans; Vrabec, Jadran
2011-11-01
This work presents the molecular simulation program ms2 that is designed for the calculation of thermodynamic properties of bulk fluids in equilibrium consisting of small electro-neutral molecules. ms2 features the two main molecular simulation techniques, molecular dynamics (MD) and Monte-Carlo. It supports the calculation of vapor-liquid equilibria of pure fluids and multi-component mixtures described by rigid molecular models on the basis of the grand equilibrium method. Furthermore, it is capable of sampling various classical ensembles and yields numerous thermodynamic properties. To evaluate the chemical potential, Widom's test molecule method and gradual insertion are implemented. Transport properties are determined by equilibrium MD simulations following the Green-Kubo formalism. ms2 is designed to meet the requirements of academia and industry, particularly achieving short response times and straightforward handling. It is written in Fortran90 and optimized for a fast execution on a broad range of computer architectures, spanning from single processor PCs over PC-clusters and vector computers to high-end parallel machines. The standard Message Passing Interface (MPI) is used for parallelization and ms2 is therefore easily portable to different computing platforms. Feature tools facilitate the interaction with the code and the interpretation of input and output files. The accuracy and reliability of ms2 has been shown for a large variety of fluids in preceding work. Program summaryProgram title:ms2 Catalogue identifier: AEJF_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Special Licence supplied by the authors No. of lines in distributed program, including test data, etc.: 82 794 No. of bytes in distributed program, including test data, etc.: 793 705 Distribution format: tar.gz Programming language: Fortran90 Computer: The
Thermodynamic state ensemble models of cis-regulation.
Directory of Open Access Journals (Sweden)
Marc S Sherman
Full Text Available A major goal in computational biology is to develop models that accurately predict a gene's expression from its surrounding regulatory DNA. Here we present one class of such models, thermodynamic state ensemble models. We describe the biochemical derivation of the thermodynamic framework in simple terms, and lay out the mathematical components that comprise each model. These components include (1 the possible states of a promoter, where a state is defined as a particular arrangement of transcription factors bound to a DNA promoter, (2 the binding constants that describe the affinity of the protein-protein and protein-DNA interactions that occur in each state, and (3 whether each state is capable of transcribing. Using these components, we demonstrate how to compute a cis-regulatory function that encodes the probability of a promoter being active. Our intention is to provide enough detail so that readers with little background in thermodynamics can compose their own cis-regulatory functions. To facilitate this goal, we also describe a matrix form of the model that can be easily coded in any programming language. This formalism has great flexibility, which we show by illustrating how phenomena such as competition between transcription factors and cooperativity are readily incorporated into these models. Using this framework, we also demonstrate that Michaelis-like functions, another class of cis-regulatory models, are a subset of the thermodynamic framework with specific assumptions. By recasting Michaelis-like functions as thermodynamic functions, we emphasize the relationship between these models and delineate the specific circumstances representable by each approach. Application of thermodynamic state ensemble models is likely to be an important tool in unraveling the physical basis of combinatorial cis-regulation and in generating formalisms that accurately predict gene expression from DNA sequence.
Thermodynamic modeling of CO2 mixtures
DEFF Research Database (Denmark)
Bjørner, Martin Gamel
Knowledge of the thermodynamic properties and phase equilibria of mixtures containing carbon dioxide (CO2) is important in several industrial processes such as enhanced oil recovery, carbon capture and storage, and supercritical extractions, where CO2 is used as a solvent. Despite this importance......, accurate predictions of the thermodynamic properties and phase equilibria of mixtures containing CO2 are challenging with classical models such as the Soave-Redlich-Kwong (SRK) equation of state (EoS). This is believed to be due to the fact, that CO2 has a large quadrupole moment which the classical models...... and with or without introducing an additional pure compound parameter. In the absence of quadrupolar compounds qCPA reduces to CPA, which itself reduces toSRK in the absence of association. As the number of adjustable parameters in thermodynamic models increase, the parameter estimation problem becomes increasingly...
Thermodynamic modeling of direct injection methanol fueled engines
International Nuclear Information System (INIS)
Shen Yuan; Bedford, Joshua; Wichman, Indrek S.
2009-01-01
In-cylinder pressure is an important parameter that is used to investigate the combustion process in internal combustion (IC) engines. In this paper, a thermodynamic model of IC engine combustion is presented and examined. A heat release function and an empirical conversion efficiency factor are introduced to solve the model. The pressure traces obtained by solving the thermodynamic model are compared with measured pressure data for a fully instrumented laboratory IC spark ignition (SI) engine. Derived scaling parameters for time to peak pressure, peak pressure, and maximum rate of pressure rise (among others) are developed and compared with the numerical simulations. The models examined here may serve as pedagogic tools and, when suitably refined, as preliminary design tools.
Thermodynamic properties of gaseous propane from model ...
African Journals Online (AJOL)
A fourth-order virial equation of state was combined with isotropic model potentials to predict accurate volumetric and caloric thermodynamic properties of propane in the gas phase. The parameters in the model were determined in a fit to speed-of-sound data alone; no other data were used. The approximation employed for ...
Thermodynamic and kinetic modelling: creep resistant materials
DEFF Research Database (Denmark)
Hald, John; Korcakova, L.; Danielsen, Hilmar Kjartansson
2008-01-01
The use of thermodynamic and kinetic modelling of microstructure evolution in materials exposed to high temperatures in power plants is demonstrated with two examples. Precipitate stability in martensitic 9–12%Cr steels is modelled including equilibrium phase stability, growth of Laves phase...
Preservation of thermodynamic structure in model reduction.
Öttinger, Hans Christian
2015-03-01
Based on the availability of an invariant manifold, we develop a model-reduction procedure that preserves thermodynamic structure. More concretely, we construct the Poisson and irreversible brackets of the general equation for the nonequilibrium reversible-irreversible coupling of nonequilibrium thermodynamics by means of the ideas originally introduced for handling constraints. The general ideas are then applied to the Kramers problem, that is, the description of transitions between two potential wells separated by a high barrier. This example reveals how a fortuitous cancellation mechanism that allows a logarithmic entropy to generate a linear diffusion equation is inherited by a master equation resulting from model reduction.
Thermodynamic vs. extrathermodynamic modeling of chromatographic retention.
Kaliszan, Roman; Wiczling, Paweł; Markuszewski, Michał J; Al-Haj, Mehdi A
2011-08-05
To predict a given physicochemical or biological property, and hence, to design rationally requested chemical entity, the relationships must be identified between the chemical structure and the desired property. Unfortunately, classical thermodynamics never predicts any property by itself, even so simple one like chromatographic retention. Therefore progress in understanding and describing molecular equilibrium between phases requires a combination of experimental measurements and correlations by means of empirical equations and approximate theories. In this work the retention prediction performance was tested of the well thermodynamically founded solvophobic theory of Horváth and co-workers of reversed-phase HPLC. The retention parameters of four series of analytes were modeled with regard to their chemical structure by: (1) observing the rules of classical thermodynamics; (2) applying an extrathermodynamically derived correction to the model based on the thermodynamic hermeneutics; (3) using extrathermodynamic, chemical intuition-based Quantitative Structure-Retention Relationships (QSRR). The combined thermodynamic/extrathermodynamic model with empirical correction accounting for the number of polar atoms provided an improvement of the agreement between the observed and the predicted retention parameters. However, a purely extrathermodynamic QSRR model, employing analyte descriptors from calculation chemistry, produced similar retention predictions. Both thermodynamic and QSRR models accounted well for abilities of analyte to participate in nonspecific, dispersive intermolecular interactions. Less reliable appeared descriptors of analyte polarity. The approach presented here can be further developed to search for proper polarity parameters, necessary to correctly predict complex physicochemical and biological properties of chemical compounds. Copyright © 2011 Elsevier B.V. All rights reserved.
Model-free thermodynamics of fluid vesicles.
Diamant, Haim
2011-12-01
Motivated by a long-standing debate concerning the nature and interrelations of surface-tension variables in fluid membranes, we reformulate the thermodynamics of a membrane vesicle as a generic two-dimensional finite system enclosing a three-dimensional volume. The formulation is shown to require two tension variables, conjugate to the intensive constraints of area per molecule and volume-to-area ratio. We obtain the relation between these two variables in various scenarios, as well as their correspondence to other definitions of tension variables for membranes. Several controversies related to membrane tension are thereby resolved on a model-free thermodynamic level. The thermodynamic formulation may be useful also for treating large-scale properties of vesicles that are insensitive to the membrane's detailed statistical mechanics and interactions.
A thermodynamically consistent model for magnetic hysteresis
International Nuclear Information System (INIS)
Ho, Kwangsoo
2014-01-01
A phenomenological constitutive model is presented to describe the magnetization curve within the context of thermodynamics. Due to the phenomenological analogy between the magnetic hysteresis and the stress hysteresis, the basic structure of the proposed model comes from rate-dependent plasticity in continuum mechanics, namely viscoplasticity. The total magnetic flux density is assumed to be the sum of reversible and irreversible parts. The model introduces the evolution laws of two internal state variables to incorporate the effect of the ever-changing internal microstructure on the current state. The conception originated from viscoplasticity enables the frequency dependence of the hysteresis curve to be modeled. - Highlights: • A constitutive model is proposed within the framework of thermodynamic principles. • The basic structure of formulation is originated from the rate-dependent plasticity. • Decomposition of the magnetic flux into reversible and irreversible parts is assumed. • Constitutive model reproduces the frequency dependency of magnetic hysteresis
A thermodynamically and microscopically motivated constitutive model for piezoceramics
International Nuclear Information System (INIS)
Kamlah, M.; Wang, Z.
2003-07-01
This progress report presents a thermodynamically and microscopically motivated constitutive model for piezoceramics within the framework of a research project supported by the Deutsche Forschungsgemeinschaft. This project is aimed at developing a finite element tool for the analysis of piezoceramic components taking into account the full range of large signal electromechanical hysteresis effects exhibited by these materials. Such a tool is necessary for the stress analysis being the basis for a reliability assessment of piezoceramic devices subject to domain switching processes. In a first step, the hysteresis phenomena of piezoceramics and their microscopic origin were discussed, and the phenomena to be described were selected. Concerning the balance laws, the simplest form consisting of balance of momentum and Gauss' Law was derived by physically motivated assumptions step by step from nonlinear thermomechanics and Maxwell's Equations. Revision of the current literature revealed that a commonly accepted thermodynamic framework for phenomenological modeling has been established in the international scientific discussion. (orig.)
High-Throughput Thermodynamic Modeling and Uncertainty Quantification for ICME
Otis, Richard A.; Liu, Zi-Kui
2017-05-01
One foundational component of the integrated computational materials engineering (ICME) and Materials Genome Initiative is the computational thermodynamics based on the calculation of phase diagrams (CALPHAD) method. The CALPHAD method pioneered by Kaufman has enabled the development of thermodynamic, atomic mobility, and molar volume databases of individual phases in the full space of temperature, composition, and sometimes pressure for technologically important multicomponent engineering materials, along with sophisticated computational tools for using the databases. In this article, our recent efforts will be presented in terms of developing new computational tools for high-throughput modeling and uncertainty quantification based on high-throughput, first-principles calculations and the CALPHAD method along with their potential propagations to downstream ICME modeling and simulations.
Technical note: A noniterative approach to modelling moist thermodynamics
Moisseeva, Nadya; Stull, Roland
2017-12-01
Formulation of noniterative mathematical expressions for moist thermodynamics presents a challenge for both numerical and theoretical modellers. This technical note offers a simple and efficient tool for approximating two common thermodynamic relationships: temperature, T, at a given pressure, P, along a saturated adiabat, T(P, θw), as well as its corresponding inverse form θw(P, T), where θw is wet-bulb potential temperature. Our method allows direct calculation of T(P, θw) and θw(P, T) on a thermodynamic domain bounded by -70 ≤ θw 1 kPa and -100 ≤ T 1 kPa, respectively. The proposed parameterizations offer high accuracy (mean absolute errors of 0.016 and 0.002 °C for T(P, θw) and θw(P, T), respectively) on a notably larger thermodynamic region than previously studied. The paper includes a method summary and a ready-to-use tool to aid atmospheric physicists in their practical applications.
Modeling thermodynamics of Fe-N phases
DEFF Research Database (Denmark)
Pekelharing, Marjon I.; Böttger, Amarante; Somers, Marcel A. J.
1999-01-01
In the present work homogeneous epsilon-nitride powders prepared at 723 K, having nitrogen contents ranging from 26.1 at. % N (z=0.29) to 31.1 at.% N (z=0.10), were investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two possible configur......In the present work homogeneous epsilon-nitride powders prepared at 723 K, having nitrogen contents ranging from 26.1 at. % N (z=0.29) to 31.1 at.% N (z=0.10), were investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two possible...
Thermodynamic modelling of Ag-Zn alloys
International Nuclear Information System (INIS)
Gomez-Acebo, T.; Sundman, B.
1998-01-01
A thermodynamic assessment of the Ag-Zn system has been done using a computerized CALPHAD (calculation of phase diagrams) technique. The liquid, α,β,ε and η phases are described by a regular solution model, the ζ phase by a two-sublattices model, and the γ phase by a four-sublattices model both based on considerations of their crystal structure and compatibility with the same phase in other systems. Some calculated phase and property diagrams are presented. (Author) 27 refs
Modeling the thermodynamic properties of plutonium
International Nuclear Information System (INIS)
Stan, Marius
2000-01-01
The golden dream of any modeling enterprise is to predict the properties of the studied system in a new and often 'hostile' environment. The basis of this kind of work is the careful, accurate assessment of the system properties in normal conditions. What 'normal conditions' means for plutonium is an interesting question itself. This work is dedicated to modeling only a fraction of the remarkable characteristics of this 'mysterious' material, that is the thermodynamic properties of its six allotropic phases (seven under pressure), the liquid phase, and the vapor phase. The goal is to provide valuable information for the calculation of alloyed plutonium phase diagrams
Modeling the thermodynamic properties of plutonium
Stan, Marius
2000-07-01
The golden dream of any modeling enterprise is to predict the properties of the studied system in a new and often "hostile" environment. The basis of this kind of work is the careful, accurate assessment of the system properties in normal conditions. What "normal conditions" means for plutonium is an interesting question itself. This work is dedicated to modeling only a fraction of the remarkable characteristics of this "mysterious" material, that is the thermodynamic properties of its six allotropic phases (seven under pressure), the liquid phase, and the vapor phase. The goal is to provide valuable information for the calculation of alloyed plutonium phase diagrams.
Thermodynamic Modeling of Savannah River Evaporators
Energy Technology Data Exchange (ETDEWEB)
Weber, C.F.
2001-08-02
A thermodynamic model based on the code SOLGASMIX is developed to calculate phase equilibrium in evaporators and related tank wastes at the Savannah River Site (SRS). This model uses the Pitzer method to calculate activity coefficients, and many of the required Pitzer parameters have been determined in the course of this work. Principal chemical species in standard SRS simulant solutions are included, and the temperature range for most parameters has been extended above 100 C. The SOLGASMIX model and calculations using the code Geochemists Workbench are compared to actual solubility data including silicate, aluminate, and aluminosilicate solutions. In addition, SOLGASMIX model calculations are also compared to transient solubility data involving SRS simulant solutions. These comparisons indicate that the SOLGASMIX predictions closely match reliable data over the range of temperature and solution composition expected in the SRS evaporator and related tanks. Predictions using the Geochemists Workbench may be unreliable, due primarily to the use of an inaccurate activity coefficient model.
Czech Academy of Sciences Publication Activity Database
Kroupa, Aleš
2013-01-01
Roč. 66, JAN (2013), s. 3-13 ISSN 0927-0256 R&D Projects: GA MŠk(CZ) OC08053 Institutional support: RVO:68081723 Keywords : Calphad method * phase diagram modelling * thermodynamic database development Subject RIV: BJ - Thermodynamics Impact factor: 1.879, year: 2013
Fermi, Enrico
1956-01-01
Indisputably, this is a modern classic of science. Based on a course of lectures delivered by the author at Columbia University, the text is elementary in treatment and remarkable for its clarity and organization. Although it is assumed that the reader is familiar with the fundamental facts of thermometry and calorimetry, no advanced mathematics beyond calculus is assumed.Partial contents: thermodynamic systems, the first law of thermodynamics (application, adiabatic transformations), the second law of thermodynamics (Carnot cycle, absolute thermodynamic temperature, thermal engines), the entr
Thermodynamic model of nonequilibrium phase transitions.
Martyushev, L M; Konovalov, M S
2011-07-01
Within the scope of a thermodynamic description using the maximum entropy production principle, transitions from one nonequilibrium (kinetic) regime to another are considered. It is shown that in the case when power-law dependencies of thermodynamic flux on force are similar for two regimes, only a transition accompanied by a positive jump of thermodynamic flux is possible between them. It is found that the difference in powers of the dependencies of thermodynamic fluxes on forces results in a number of interesting nonequilibrium transitions between kinetic regimes, including the reentrant one with a negative jump of thermodynamic flux.
Thermodynamic modeling of the Co-Fe-O system
DEFF Research Database (Denmark)
Zhang, Weiwei; Chen, Ming
2013-01-01
As a part of the research project aimed at developing a thermodynamic database of the La-Sr-Co-Fe-O system for applications in Solid Oxide Fuel Cells (SOFCs), the Co-Fe-O subsystem was thermodynamically re-modeled in the present work using the CALPHAD methodology. The solid phases were described...... using the Compound Energy Formalism (CEF) and the ionized liquid was modeled with the ionic two-sublattice model based on CEF. A set of self-consistent thermodynamic parameters was obtained eventually. Calculated phase diagrams and thermodynamic properties are presented and compared with experimental...
A constitutive model for magnetostriction based on thermodynamic framework
International Nuclear Information System (INIS)
Ho, Kwangsoo
2016-01-01
This work presents a general framework for the continuum-based formulation of dissipative materials with magneto–mechanical coupling in the viewpoint of irreversible thermodynamics. The thermodynamically consistent model developed for the magnetic hysteresis is extended to include the magnetostrictive effect. The dissipative and hysteretic response of magnetostrictive materials is captured through the introduction of internal state variables. The evolution rate of magnetostrictive strain as well as magnetization is derived from thermodynamic and dissipative potentials in accordance with the general principles of thermodynamics. It is then demonstrated that the constitutive model is competent to describe the magneto-mechanical behavior by comparing simulation results with the experimental data reported in the literature. - Highlights: • A thermodynamically consistent model is proposed to describe the magneto-mechanical coupling effect. • Internal state variables are introduced to capture the dissipative material response. • The evolution rate of the magnetostrictive strain is derived through thermodynamic and dissipation potentials.
Energy Technology Data Exchange (ETDEWEB)
Abergel, Rebecca J.; D' Aleo, Anthony; Ng Pak Leung, Clara; Shuh, David; Raymond, Kenneth
2009-11-20
While widely used in bioassays, the spectrofluorimetric method described here uses the antenna effect as a tool to probe the thermodynamic parameters of ligands that sensitize lanthanide luminescence. The Eu3+ coordination chemistry, solution thermodynamic stability and photophysical properties of the spermine-based hydroxypyridonate octadentate chelator 3,4,3-LI(1,2-HOPO) are reported. The complex [EuIII(3,4,3-LI(1,2-HOPO))]- luminesces with a long lifetime (805 mu s) and a quantum yield of 7.0percent in aqueous solution, at pH 7.4. These remarkable optical properties were exploited to determine the high (and proton-independent) stability of the complex (log beta 110 = 20.2(2)) and to define the influence of the ligand scaffold on the stability and photophysical properties.
Evaluation of the Thermodynamic Models for the Thermal Diffusion Factor
DEFF Research Database (Denmark)
Gonzalez-Bagnoli, Mariana G.; Shapiro, Alexander; Stenby, Erling Halfdan
2003-01-01
Over the years, several thermodynamic models for the thermal diffusion factors for binary mixtures have been proposed. The goal of this paper is to test some of these models in combination with different equations of state. We tested the following models: those proposed by Rutherford and Drickamer...... we applied different thermodynamic models, such as the Soave-Redlich-Kwong and the Peng-Robinson equations of state. The necessity to try different thermo-dynamic models is caused by the high sensitivity of the thermal diffusion factors to the values of the partial molar properties. Two different...
Thermodynamic Modeling of Sr/TRU Removal
International Nuclear Information System (INIS)
Felmy, A.R.
2000-01-01
This report summarizes the development and application of a thermodynamic modeling capability designed to treat the Envelope C wastes containing organic complexants. A complete description of the model development is presented. In addition, the model was utilized to help gain insight into the chemical processes responsible for the observed levels of Sr, TRU, Fe, and Cr removal from the diluted feed from tank 241-AN-107 which had been treated with Sr and permanganate. Modeling results are presented for Sr, Nd(III)/Eu(III), Fe, Cr, Mn, and the major electrolyte components of the waste (i.e. NO 3 , NO 2 , F,...). On an overall basis the added Sr is predicted to precipitate as SrCO 3 (c) and the MnO 4 - reduced by the NO 2 - and precipitated as a Mn oxide. These effects result in only minor changes to the bulk electrolyte chemistry, specifically, decreases in NO 2 - and CO 3 2- , and increases in NO 3 - and OH - . All of these predictions are in agreement with the experimental observations. The modeling also indicates that the majority of the Sr, TRU's (or Nd(III)/Eu(III)) analogs, and Fe are tied up with the organic complexants. The Sr and permanganate additions are not predicted to effect these chelate complexes significantly owing to the precipitation of insoluble Mn oxides or SrCO 3 . These insoluble phases maintain low dissolved concentrations of Mn and Sr which do not affect any of the other components tied up with the complexants. It appears that the removal of the Fe and TRU'S during the treatment process is most likely as a result of adsorption or occlusion on/into the Mn oxides or SrCO 3 , not as direct displacement from the complexants into precipitates. Recommendations are made for further studies that are needed to help resolve these issues
Comparison of thermodynamic databases used in geochemical modelling
International Nuclear Information System (INIS)
Chandratillake, M.R.; Newton, G.W.A.; Robinson, V.J.
1988-05-01
Four thermodynamic databases used by European groups for geochemical modelling have been compared. Thermodynamic data for both aqueous species and solid species have been listed. When the values are directly comparable any differences between them have been highlighted at two levels of significance. (author)
Green Infrastructure Modeling Tools
Modeling tools support planning and design decisions on a range of scales from setting a green infrastructure target for an entire watershed to designing a green infrastructure practice for a particular site.
SOLGAS refined: A computerized thermodynamic equilibrium calculation tool
Energy Technology Data Exchange (ETDEWEB)
Trowbridge, L.D.; Leitnaker, J.M.
1993-11-01
SOLGAS, an early computer program for calculating equilibrium in a chemical system, has been made more user-friendly, and several{open_quote} bells and whistles{close_quotes} have been added. The necessity to include elemental species has been eliminated. The input of large numbers of starting conditions has been automated. A revised format for entering data simplifies and reduces chances for error. Calculated errors by SOLGAS are flagged, and several programming errors are corrected. Auxiliary programs are available to assemble and partially automate plotting of large amounts of data. Thermodynamic input data can be changed {open_quotes}on line.{close_quote} The program can be operated with or without a co-processor. Copies of the program, suitable for the IBM-PC or compatible with at least 384 bytes of low RAM, are available from the authors.
SOLGAS refined: A computerized thermodynamic equilibrium calculation tool
International Nuclear Information System (INIS)
Trowbridge, L.D.; Leitnaker, J.M.
1993-11-01
SOLGAS, an early computer program for calculating equilibrium in a chemical system, has been made more user-friendly, and several open-quote bells and whistlesclose quotes have been added. The necessity to include elemental species has been eliminated. The input of large numbers of starting conditions has been automated. A revised format for entering data simplifies and reduces chances for error. Calculated errors by SOLGAS are flagged, and several programming errors are corrected. Auxiliary programs are available to assemble and partially automate plotting of large amounts of data. Thermodynamic input data can be changed open-quotes on line.close-quote The program can be operated with or without a co-processor. Copies of the program, suitable for the IBM-PC or compatible with at least 384 bytes of low RAM, are available from the authors
Population Density Modeling Tool
2012-06-26
194 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke 26 June 2012 Distribution...MARYLAND NAWCADPAX/TR-2012/194 26 June 2012 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke...information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE 26
International Nuclear Information System (INIS)
Zanchini, E.
1988-01-01
The definition of energy, in thermodynamics, is dependent by starting operative definitions of the basic concepts of physics on which it rests, such as those of isolated systems, ambient of a system, separable system and set of separable states. Then the definition of energy is rigorously extended to open systems. The extension gives a clear physical meaning to the concept of energy difference between two states with arbitrary different compositions
On the modelling of microsegregation in steels involving thermodynamic databases
International Nuclear Information System (INIS)
You, D; Bernhard, C; Michelic, S; Wieser, G; Presoly, P
2016-01-01
A microsegregation model involving thermodynamic database based on Ohnaka's model is proposed. In the model, the thermodynamic database is applied for equilibrium calculation. Multicomponent alloy effects on partition coefficients and equilibrium temperatures are accounted for. Microsegregation and partition coefficients calculated using different databases exhibit significant differences. The segregated concentrations predicted using the optimized database are in good agreement with the measured inter-dendritic concentrations. (paper)
Modeling interfacial dynamics using nonequilibrium thermodynamics frameworks
Sagis, L.M.C.
2013-01-01
In recent years several nonequilibrium thermodynamic frameworks have been developed capable of describing the dynamics of multiphase systems with complex microstructured interfaces. In this paper we present an overview of these frameworks. We will discuss interfacial dynamics in the context of the
Thermodynamic modeling to analyse composition of carbonaceous ...
Indian Academy of Sciences (India)
the present work. Keywords. MOCVD; manganese oxide; carbon matrix; thermodynamic analysis; phase stability diagram. 1. Introduction ... als, including oxides, nitrides, and compound semiconduc- tors (Vossen and Kern 1991). ... 12. Sukanya Dhar et al nanostructured MnO in a matrix of graphitic carbon, both of which are ...
Thermodynamic modeling to analyse composition of carbonaceous ...
Indian Academy of Sciences (India)
Equilibrium thermodynamic analysis has been applied to the low-pressure MOCVD process using manganese acetylacetonate as the precursor. ``CVD phase stability diagrams” have been constructed separately for the processes carried out in argon and oxygen ambient, depicting the compositions of the resulting films as ...
An Overview of a Continuum Mechanic Approach to a Thermodynamic Model of Failure
National Research Council Canada - National Science Library
Palazotto, A
1998-01-01
.... An overview of the thermodynamic definitions, concepts, and principles will be presented. This overview of the thermodynamics is necessary to provided the background needed to understand the damage model, which is based on thermodynamic principles...
A Thermodynamic Point of View on Dark Energy Models
Directory of Open Access Journals (Sweden)
Vincenzo F. Cardone
2017-07-01
Full Text Available We present a conjugate analysis of two different dark energy models, namely the Barboza–Alcaniz parameterization and the phenomenologically-motivated Hobbit model, investigating both their agreement with observational data and their thermodynamical properties. We successfully fit a wide dataset including the Hubble diagram of Type Ia Supernovae, the Hubble rate expansion parameter as measured from cosmic chronometers, the baryon acoustic oscillations (BAO standard ruler data and the Planck distance priors. This analysis allows us to constrain the model parameters, thus pointing at the region of the wide parameters space, which is worth focusing on. As a novel step, we exploit the strong connection between gravity and thermodynamics to further check models’ viability by investigating their thermodynamical quantities. In particular, we study whether the cosmological scenario fulfills the generalized second law of thermodynamics, and moreover, we contrast the two models, asking whether the evolution of the total entropy is in agreement with the expectation for a closed system. As a general result, we discuss whether thermodynamic constraints can be a valid complementary way to both constrain dark energy models and differentiate among rival scenarios.
Zhou, S.; Solana, J. R.
2018-03-01
Monte Carlo NVT simulations have been performed to obtain the thermodynamic and structural properties and perturbation coefficients up to third order in the inverse temperature expansion of the Helmholtz free energy of fluids with potential models proposed in the literature for diamond and wurtzite lattices. These data are used to analyze performance of a coupling parameter series expansion (CPSE). The main findings are summarized as follows, (1) The CPSE provides accurate predictions of the first three coefficient in the inverse temperature expansion of Helmholtz free energy for the potential models considered and the thermodynamic properties of these fluids are predicted more accurately when the CPSE is truncated at second or third order. (2) The Barker-Henderson (BH) recipe is appropriate for determining the effective hard sphere diameter for strongly repulsive potential cores, but its performance worsens with increasing the softness of the potential core. (3) For some thermodynamic properties the first-order CPSE works better for the diamond potential, whose tail is dominated by repulsive interactions, than for the potential, whose tail is dominated by attractive interactions. However, the first-order CPSE provides unsatisfactory results for the excess internal energy and constant-volume excess heat capacity for the two potential models.
Thermodynamic modelling of alkali-activated slag cements
International Nuclear Information System (INIS)
Myers, Rupert J.; Lothenbach, Barbara; Bernal, Susan A.; Provis, John L.
2015-01-01
Highlights: • A thermodynamic modelling analysis of alkali-activated slag cements is presented. • Thermodynamic database describes zeolites, alkali carbonates, C–(N–)A–S–H gel. • Updated thermodynamic model for Mg–Al layered double hydroxides. • Description of phase assemblages in Na 2 SiO 3 - and Na 2 CO 3 -activated slag cements. • Phase diagrams for NaOH-activated and Na 2 SiO 3 -activated slag cements are simulated. - Abstract: This paper presents a thermodynamic modelling analysis of alkali-activated slag-based cements, which are high performance and potentially low-CO 2 binders relative to Portland cement. The thermodynamic database used here contains a calcium (alkali) aluminosilicate hydrate ideal solid solution model (CNASH-ss), alkali carbonate and zeolite phases, and an ideal solid solution model for a hydrotalcite-like Mg–Al layered double hydroxide phase. Simulated phase diagrams for NaOH- and Na 2 SiO 3 -activated slag-based cements demonstrate the high stability of zeolites and other solid phases in these materials. Thermodynamic modelling provides a good description of the chemical compositions and types of phases formed in Na 2 SiO 3 -activated slag cements over the most relevant bulk chemical composition range for these cements, and the simulated volumetric properties of the cement paste are consistent with previously measured and estimated values. Experimentally determined and simulated solid phase assemblages for Na 2 CO 3 -activated slag cements were also found to be in good agreement. These results can be used to design the chemistry of alkali-activated slag-based cements, to further promote the uptake of this technology and valorisation of metallurgical slags
A Systematic Identification Method for Thermodynamic Property Modelling
DEFF Research Database (Denmark)
Ana Perederic, Olivia; Cunico, Larissa; Sarup, Bent
2017-01-01
In this work, a systematic identification method for thermodynamic property modelling is proposed. The aim of the method is to improve the quality of phase equilibria prediction by group contribution based property prediction models. The method is applied to lipid systems where the Original UNIFAC...
A Thermodynamic Mixed-Solid Asphaltene Precipitation Model
DEFF Research Database (Denmark)
Lindeloff, Niels; Heidemann, R.A.; Andersen, Simon Ivar
1998-01-01
A simple model for the prediction of asphaltene precipitation is proposed. The model is based on an equation of state and uses standard thermodynamics, thus assuming that the precipitation phenomenon is a reversible process. The solid phase is treated as an ideal multicomponent mixture. An activity...
DEFF Research Database (Denmark)
Puig Arnavat, Maria; Bruno, Juan Carlos; Coronas, Alberto
2012-01-01
This paper presents a mathematical model for biomass gasification processes developed in the equation solver program Engineering Equation Solver (EES) with an implemented user-friendly interface. It is based on thermodynamic equilibrium calculations and includes some modifications to be adapted......, and oxygen enrichment] on producer gas. The model predicts the behavior of different kinds of biomass and becomes a useful tool to simulate the biomass gasification process by allowing its integration in complete energy supply systems, such as co-generation plants....
A THERMODYNAMIC CAVITATION MODEL APPLICABLE TO HIGH TEMPERATURE FLOW
Directory of Open Access Journals (Sweden)
De-Min Liu
2011-01-01
Full Text Available Cavitation is not only related with pressure, but also affected by temperature. Under high temperature, temperature depression of liquids is caused by latent heat of vaporization. The cavitation characteristics under such condition are different from those under room temperature. The paper focuses on thermodynamic cavitation based on the Rayleigh-Plesset equation and modifies the mass transfer equation with fully consideration of the thermodynamic effects and physical properties. To validate the modified model, the external and internal flow fields, such as hydrofoil NACA0015 and nozzle, are calculated, respectively. The hydrofoil NACA0015's cavitation characteristic is calculated by the modified model at different temperatures. The pressure coefficient is found in accordance with the experimental data. The nozzle cavitation under the thermodynamic condition is calculated and compared with the experiment.
Thermodynamic modeling of the Sr-Co-Fe-O system
DEFF Research Database (Denmark)
Zhang, Wei Wei; Povoden-Karadeniz, Erwin; Chen, Ming
2016-01-01
This paper reviews and assesses phase equilibria and thermodynamic properties of phases in the Sr-Co-Fe-O system, with a focus on oxides, especially the SrCo1 - xFexO3 - δ perovskite. In our work, the SrCo1 - xFexO3 - δ perovskite was modeled with a three-sublattice model, where the three...... sublattices correspond to the A, B and oxygen sites in an ABO3 perovskite, respectively. A number of other important ternary oxide phases in Sr-Co-O and Sr-Co-Fe-O were also considered. Available thermodynamic and phase diagram data were carefully assessed. A thermodynamic description of Sr-Co-O was derived...... using the CALPHAD approach and was further extrapolated to that of Sr-Co-Fe-O. The thermodynamic database of Sr-Co-Fe-O established in this work allows for calculating phase diagrams, thermodynamic properties, cation distribution and defect chemistry properties, and therefore enables material...
Thermodynamics-based models of transcriptional regulation with gene sequence.
Wang, Shuqiang; Shen, Yanyan; Hu, Jinxing
2015-12-01
Quantitative models of gene regulatory activity have the potential to improve our mechanistic understanding of transcriptional regulation. However, the few models available today have been based on simplistic assumptions about the sequences being modeled or heuristic approximations of the underlying regulatory mechanisms. In this work, we have developed a thermodynamics-based model to predict gene expression driven by any DNA sequence. The proposed model relies on a continuous time, differential equation description of transcriptional dynamics. The sequence features of the promoter are exploited to derive the binding affinity which is derived based on statistical molecular thermodynamics. Experimental results show that the proposed model can effectively identify the activity levels of transcription factors and the regulatory parameters. Comparing with the previous models, the proposed model can reveal more biological sense.
THERMODYNAMIC MODELING AND FIRST-PRINCIPLES CALCULATIONS
Energy Technology Data Exchange (ETDEWEB)
Turchi, P; Abrikosov, I; Burton, B; Fries, S; Grimvall, G; Kaufman, L; Korzhavyi, P; Manga, R; Ohno, M; Pisch, A; Scott, A; Zhang, W
2005-12-15
The increased application of quantum mechanical-based methodologies to the study of alloy stability has required a re-assessment of the field. The focus is mainly on inorganic materials in the solid state. In a first part, after a brief overview of the so-called ab initio methods with their approximations, constraints, and limitations, recommendations are made for a good usage of first-principles codes with a set of qualifiers. Examples are given to illustrate the power and the limitations of ab initio codes. However, despite the ''success'' of these methodologies, thermodynamics of complex multi-component alloys, as used in engineering applications, requires a more versatile approach presently afforded within CALPHAD. Hence, in a second part, the links that presently exist between ab initio methodologies, experiments, and CALPHAD approach are examined with illustrations. Finally, the issues of dynamical instability and of the role of lattice vibrations that still constitute the subject of ample discussions within the CALPHAD community are revisited in the light of the current knowledge with a set of recommendations.
Carvalho, Eduardo O.; Araki, Marcelo K.; Freitas, Sergio F.; de Godoy, Carlos M. G.; Faljoni-Alario, Adelaide; Frare-Junior, Pedro L.; Nantes, Iseli L.
2009-01-01
This study describes the application and evaluation of a novel didactic tool (thermodynamic device) developed for students in the area of biology who have conceptual deficiencies that render the learning of thermodynamic principles difficult. Systems of communicant vessels with equal and different compartments were constructed to correlate the…
Thermodynamic modelling of detonation H-N-O high explosives
Bogdanova, Yu A.; Gubin, S. A.; Anikeev, A. A.; Victorov, S. B.
2016-09-01
The multiphase model of a detonation products based on the equations of state (EOS) of chemically reacting H-N-O systems which is used in the thermodynamic TDS code is presented. This model is applicable over a wide range of temperatures and density. This model consists of theoretically reasonable EOS for a multicomponent gas (fluid) phase. The calculations of detonation based on the presented model to be in good agreement with experimental data.
Thermodynamic modeling and kinetics simulation of precipitate phases in AISI 316 stainless steels
International Nuclear Information System (INIS)
Yang, Y.; Busby, J.T.
2014-01-01
This work aims at utilizing modern computational microstructural modeling tools to accelerate the understanding of phase stability in austenitic steels under extended thermal aging. Using the CALPHAD approach, a thermodynamic database OCTANT (ORNL Computational Thermodynamics for Applied Nuclear Technology), including elements of Fe, C, Cr, Ni, Mn, Mo, Si, and Ti, has been developed with a focus on reliable thermodynamic modeling of precipitate phases in AISI 316 austenitic stainless steels. The thermodynamic database was validated by comparing the calculated results with experimental data from commercial 316 austenitic steels. The developed computational thermodynamics was then coupled with precipitation kinetics simulation to understand the temporal evolution of precipitates in austenitic steels under long-term thermal aging (up to 600,000 h) at a temperature regime from 300 to 900 °C. This study discusses the effect of dislocation density and difusion coefficients on the precipitation kinetics at low temperatures, which shed a light on investigating the phase stability and transformation in austenitic steels used in light water reactors
Thermodynamic model of natural, medieval and nuclear waste glass durability
International Nuclear Information System (INIS)
Jantzen, C.M.; Plodinec, M.J.
1983-01-01
A thermodynamic model of glass durability based on hydration of structural units has been applied to natural glass, medieval window glasses, and glasses containing nuclear waste. The relative durability predicted from the calculated thermodynamics correlates directly with the experimentally observed release of structural silicon in the leaching solution in short-term laboratory tests. By choosing natural glasses and ancient glasses whose long-term performance is known, and which bracket the durability of waste glasses, the long-term stability of nuclear waste glasses can be interpolated among these materials. The current Savannah River defense waste glass formulation is as durable as natural basalt from the Hanford Reservation (10 6 years old). The thermodynamic hydration energy is shown to be related to the bond energetics of the glass. 69 references, 2 figures, 1 table
Kinetic modelling and thermodynamic studies on purification of ...
African Journals Online (AJOL)
Adsorbent capacities have been determined by mathematical fitting of equilibrium data using the most common isotherms: Freundlich isotherm and Langmuir isotherm. Several kinetic models have been applied to the process. Thermodynamic parameters: △So, △Ho, △Go and Ea (kJ/mol) have been determined.
WATEQ3 geochemical model: thermodynamic data for several additional solids
International Nuclear Information System (INIS)
Krupka, K.M.; Jenne, E.A.
1982-09-01
Geochemical models such as WATEQ3 can be used to model the concentrations of water-soluble pollutants that may result from the disposal of nuclear waste and retorted oil shale. However, for a model to competently deal with these water-soluble pollutants, an adequate thermodynamic data base must be provided that includes elements identified as important in modeling these pollutants. To this end, several minerals and related solid phases were identified that were absent from the thermodynamic data base of WATEQ3. In this study, the thermodynamic data for the identified solids were compiled and selected from several published tabulations of thermodynamic data. For these solids, an accepted Gibbs free energy of formation, ΔG 0 /sub f,298/, was selected for each solid phase based on the recentness of the tabulated data and on considerations of internal consistency with respect to both the published tabulations and the existing data in WATEQ3. For those solids not included in these published tabulations, Gibbs free energies of formation were calculated from published solubility data (e.g., lepidocrocite), or were estimated (e.g., nontronite) using a free-energy summation method described by Mattigod and Sposito (1978). The accepted or estimated free energies were then combined with internally consistent, ancillary thermodynamic data to calculate equilibrium constants for the hydrolysis reactions of these minerals and related solid phases. Including these values in the WATEQ3 data base increased the competency of this geochemical model in applications associated with the disposal of nuclear waste and retorted oil shale. Additional minerals and related solid phases that need to be added to the solubility submodel will be identified as modeling applications continue in these two programs
International Nuclear Information System (INIS)
Ohno, M.; Kozlov, A.; Arroyave, R.; Liu, Z.K.; Schmid-Fetzer, R.
2006-01-01
The thermodynamic model of the Ca-Sn system was obtained, utilizing the first-principles total energies and heat capacities calculated from 0 K to the melting points of the major phases. Since the first-principles result for the formation energy of the dominating Ca 2 Sn intermetallic phase is drastically different from the reported experimental data, we performed two types of thermodynamic modeling: one based on the first-principles output and the other based on the experimental data. In the former modeling, the Gibbs energies of the intermetallic compounds were fully quantified from the first-principles finite temperature properties and the superiority of the former thermodynamic description is demonstrated. It is shown that it is the combination of finite temperature first-principle calculations and the Calphad modeling tool that provides a sound basis for identifying and deciding on conflicting key thermodynamic data in the Ca-Sn system
Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling
Directory of Open Access Journals (Sweden)
A. S. Almeida
2008-06-01
Full Text Available A mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. Special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. The thermodynamic model is based on a cubic equation of state and a mixing rule applied to the low-pressure vapor-liquid equilibrium of polymeric solutions, suitable for modeling the auto-refrigerated polymerization reactors, which use the vaporization rate to remove the reaction heat from the exothermic reactions. The simulation results show the high predictive capability of the proposed model when compared with plant data for conversion, average molecular weights, polydispersity, melt flow index, and thermal properties for different polymer grades.
Thermodynamic modeling of the Fe-Mg-Si system
Directory of Open Access Journals (Sweden)
Du Y.
2007-01-01
Full Text Available A thermo dynamic modeling for the Fe-Mg-Si system is conducted. All of the experimental phase diagram and thermodynamic data available from the literature are critically reviewed and assessed using thermo dynamic models for the Gibbs energies of individual phases. The thermodynamic parameters for ternary liquid as well as binary phases αFeSi, (high-temperature form of FeSi2 and FeSi showing noticeable solubilities for Mg are evaluated in the optimization. Comparisons between the calculated and measured phase diagrams show that the measured isothermal six-lions at 1600°, 1454°, 727° and 710°C, the observed regions of primary phases are satisfactorily accounted for by the thermodynamic description. The limited thermodynamic data concerning the activity of Mg in liquid at 1350°C are found to be inconsistent with the well established phase relations. The liquidus projection and reaction scheme for the entire Fe-Mg-Si system are also presented. .
Thermodynamics of Paint Related Systems with Engineering Models
DEFF Research Database (Denmark)
Lindvig, Thomas; Michelsen, Michael Locht; Kontogeorgis, Georgios
2001-01-01
to solid surfaces and drying. Many engineering models have been applied over the last decades for solutions with commoditity polymers. In this work the performance of some of these models is investigated for paint-related systems, focusing on those drying by the so-called " lacquer mechanism " (evaporation......Paints are complex materials composed of polymers (binders) dissolved in one or more solvents, pigments, and other additives. The thermodynamics of such systems is essential, for example, for selecting improved solvents and understanding a number of phenomena related especially! to adhesion...... that, despite the uncertainties involved, several models yield reasonably accurate activity coefficients, even at infinite dilution. Thus, engineering models may be useful for solvent selection via semiempirical rules of thumb, which are based on thermodynamic considerations....
Chemical Thermodynamics of Aqueous Atmospheric Aerosols: Modeling and Microfluidic Measurements
Nandy, L.; Dutcher, C. S.
2017-12-01
Accurate predictions of gas-liquid-solid equilibrium phase partitioning of atmospheric aerosols by thermodynamic modeling and measurements is critical for determining particle composition and internal structure at conditions relevant to the atmosphere. Organic acids that originate from biomass burning, and direct biogenic emission make up a significant fraction of the organic mass in atmospheric aerosol particles. In addition, inorganic compounds like ammonium sulfate and sea salt also exist in atmospheric aerosols, that results in a mixture of single, double or triple charged ions, and non-dissociated and partially dissociated organic acids. Statistical mechanics based on a multilayer adsorption isotherm model can be applied to these complex aqueous environments for predictions of thermodynamic properties. In this work, thermodynamic analytic predictive models are developed for multicomponent aqueous solutions (consisting of partially dissociating organic and inorganic acids, fully dissociating symmetric and asymmetric electrolytes, and neutral organic compounds) over the entire relative humidity range, that represent a significant advancement towards a fully predictive model. The model is also developed at varied temperatures for electrolytes and organic compounds the data for which are available at different temperatures. In addition to the modeling approach, water loss of multicomponent aerosol particles is measured by microfluidic experiments to parameterize and validate the model. In the experimental microfluidic measurements, atmospheric aerosol droplet chemical mimics (organic acids and secondary organic aerosol (SOA) samples) are generated in microfluidic channels and stored and imaged in passive traps until dehydration to study the influence of relative humidity and water loss on phase behavior.
Integrated thermodynamic model for ignition target performance
Directory of Open Access Journals (Sweden)
Springer P.T.
2013-11-01
Full Text Available We have derived a 3-dimensional synthetic model for NIF implosion conditions, by predicting and optimizing fits to a broad set of x-ray and nuclear diagnostics obtained on each shot. By matching x-ray images, burn width, neutron time-of-flight ion temperature, yield, and fuel ρr, we obtain nearly unique constraints on conditions in the hotspot and fuel in a model that is entirely consistent with the observables. This model allows us to determine hotspot density, pressure, areal density (ρr, total energy, and other ignition-relevant parameters not available from any single diagnostic. This article describes the model and its application to National Ignition Facility (NIF tritium–hydrogen–deuterium (THD and DT implosion data, and provides an explanation for the large yield and ρr degradation compared to numerical code predictions.
Thermodynamical aspects of running vacuum models
Energy Technology Data Exchange (ETDEWEB)
Lima, J.A.S. [Universidade de Sao Paulo, Departamento de Astronomia, Sao Paulo (Brazil); Basilakos, Spyros [Academy of Athens, Research Center for Astronomy and Applied Mathematics, Athens (Greece); Sola, Joan [Univ. de Barcelona, High Energy Physics Group, Dept. d' Estructura i Constituents de la Materia, Institut de Ciencies del Cosmos (ICC), Barcelona, Catalonia (Spain)
2016-04-15
The thermal history of a large class of running vacuum models in which the effective cosmological term is described by a truncated power series of the Hubble rate, whose dominant term is Λ(H) ∝ H{sup n+2}, is discussed in detail. Specifically, by assuming that the ultrarelativistic particles produced by the vacuum decay emerge into space-time in such a way that its energy density ρ{sub r} ∝ T{sup 4}, the temperature evolution law and the increasing entropy function are analytically calculated. For the whole class of vacuum models explored here we find that the primeval value of the comoving radiation entropy density (associated to effectively massless particles) starts from zero and evolves extremely fast until reaching a maximum near the end of the vacuum decay phase, where it saturates. The late-time conservation of the radiation entropy during the adiabatic FRW phase also guarantees that the whole class of running vacuum models predicts the same correct value of the present day entropy, S{sub 0} ∝ 10{sup 87}-10{sup 88} (in natural units), independently of the initial conditions. In addition, by assuming Gibbons¨CHawking temperature as an initial condition, we find that the ratio between the late-time and primordial vacuum energy densities is in agreement with naive estimates from quantum field theory, namely, ρ{sub Λ0}/ρ{sub ΛI} 10{sup -123}. Such results are independent on the power n and suggests that the observed Universe may evolve smoothly between two extreme, unstable, non-singular de Sitter phases. (orig.)
Thermodynamics of a model solid with magnetoelastic coupling
Szałowski, K.; Balcerzak, T.; Jaščur, M.
2018-01-01
In the paper a study of a model magnetoelastic solid system is presented. The system of interest is a mean-field magnet with nearest-neighbour ferromagnetic interactions and the underlying s.c. crystalline lattice with the long-range Morse interatomic potential and the anharmonic Debye model for the lattice vibrations. The influence of the external magnetic field on the thermodynamics is investigated, with special emphasis put on the consequences of the magnetoelastic coupling, introduced by the power-law distance dependence of the magnetic exchange integral. Within the fully self-consistent, Gibbs energy-based formalism such thermodynamic quantities as the entropy, the specific heat as well as the lattice and magnetic response functions are calculated and discussed. To complete the picture, the magnetocaloric effect is characterized by analysis of the isothermal entropy change and the adiabatic temperature change in the presence of the external pressure.
Advances on statistical/thermodynamical models for unpolarized structure functions
Energy Technology Data Exchange (ETDEWEB)
Trevisan, Luis A. [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR (Brazil); Mirez, Carlos [Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus do Mucuri, 39803-371, Teofilo Otoni, Minas Gerais (Brazil); Tomio, Lauro [Instituto de Fisica Teorica, Universidade Estadual Paulista, R. Dr. Bento Teobaldo Ferraz 271, Bl II Barra Funda, 01140070, Sao Paulo, SP (Brazil)
2013-03-25
During the eights and nineties many statistical/thermodynamical models were proposed to describe the nucleons' structure functions and distribution of the quarks in the hadrons. Most of these models describe the compound quarks and gluons inside the nucleon as a Fermi / Bose gas respectively, confined in a MIT bag with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries {sup -}d/{sup -}u and {sup -}d-{sup -}u.
International Nuclear Information System (INIS)
Lim, Gyeong Hui
2008-03-01
This book consists of 15 chapters, which are basic conception and meaning of statistical thermodynamics, Maxwell-Boltzmann's statistics, ensemble, thermodynamics function and fluctuation, statistical dynamics with independent particle system, ideal molecular system, chemical equilibrium and chemical reaction rate in ideal gas mixture, classical statistical thermodynamics, ideal lattice model, lattice statistics and nonideal lattice model, imperfect gas theory on liquid, theory on solution, statistical thermodynamics of interface, statistical thermodynamics of a high molecule system and quantum statistics
Averesch, Nils J H; Martínez, Verónica S; Nielsen, Lars K; Krömer, Jens O
2018-02-16
Adipic acid, a nylon-6,6 precursor, has recently gained popularity in synthetic biology. Here, 16 different production routes to adipic acid were evaluated using a novel tool for network-embedded thermodynamic analysis of elementary flux modes. The tool distinguishes between thermodynamically feasible and infeasible modes under determined metabolite concentrations, allowing the thermodynamic feasibility of theoretical yields to be assessed. Further, patterns that always caused infeasible flux distributions were identified, which will aid the development of tailored strain design. A review of cellular efflux mechanisms revealed that significant accumulation of extracellular product is only possible if coupled with ATP hydrolysis. A stoichiometric analysis demonstrated that the maximum theoretical product carbon yield heavily depends on the metabolic route, ranging from 32 to 99% on glucose and/or palmitate in Escherichia coli and Saccharomyces cerevisiae metabolic models. Equally important, metabolite concentrations appeared to be thermodynamically restricted in several pathways. Consequently, the number of thermodynamically feasible flux distributions was reduced, in some cases even rendering whole pathways infeasible, highlighting the importance of pathway choice. Only routes based on the shikimate pathway were thermodynamically favorable over a large concentration and pH range. The low pH capability of S. cerevisiae shifted the thermodynamic equilibrium of some pathways toward product formation. One identified infeasible-pattern revealed that the reversibility of the mitochondrial malate dehydrogenase contradicted the current state of knowledge, which imposes a major restriction on the metabolism of S. cerevisiae. Finally, the evaluation of industrially relevant constraints revealed that two shikimate pathway-based routes in E. coli were the most robust.
A Thermodynamic Mixed-Solid Asphaltene Precipitation Model
DEFF Research Database (Denmark)
Lindeloff, Niels; Heidemann, R.A.; Andersen, Simon Ivar
1998-01-01
A simple model for the prediction of asphaltene precipitation is proposed. The model is based on an equation of state and uses standard thermodynamics, thus assuming that the precipitation phenomenon is a reversible process. The solid phase is treated as an ideal multicomponent mixture. An activity......, that out of the total PNA composition of a crude, the asphaltenes and resins are mainly aromatic-naphtenic in their nature. The predictions shows the correct qualitative behavior with respect to temperature and pressure, but due to lack of data the model was not evaluated quantitatively with respect...
Thermodynamically consistent mesoscopic model of the ferro/paramagnetic transition
Czech Academy of Sciences Publication Activity Database
Benešová, Barbora; Kružík, Martin; Roubíček, Tomáš
2013-01-01
Roč. 64, Č. 1 (2013), s. 1-28 ISSN 0044-2275 R&D Projects: GA AV ČR IAA100750802; GA ČR GA106/09/1573; GA ČR GAP201/10/0357 Grant - others:GA ČR(CZ) GA106/08/1397; GA MŠk(CZ) LC06052 Program:GA; LC Institutional support: RVO:67985556 Keywords : ferro-para-magnetism * evolution * thermodynamics Subject RIV: BA - General Mathematics; BA - General Mathematics (UT-L) Impact factor: 1.214, year: 2013 http://library.utia.cas.cz/separaty/2012/MTR/kruzik-thermodynamically consistent mesoscopic model of the ferro-paramagnetic transition.pdf
Thermodynamic modelling of fast dopant diffusion in Si
Saltas, V.; Chroneos, A.; Vallianatos, F.
2018-04-01
In the present study, nickel and copper fast diffusion in silicon is investigated in the framework of the cBΩ thermodynamic model, which connects point defect parameters with the bulk elastic and expansion properties. All the calculated point defect thermodynamic properties (activation Gibbs free energy, activation enthalpy, activation entropy, and activation volume) exhibit temperature dependence due to the non-linear anharmonic behavior of the isothermal bulk modulus of Si. Calculated activation enthalpies (0.15-0.16 eV for Ni and 0.17-0.19 eV for Cu) are in agreement with the reported experimental results. Small values of calculated activation volumes for both dopants (˜4% of the mean atomic volume) are consistent with the interstitial diffusion of Ni and Cu in Si.
A Zeroth Law Compatible Model to Kerr Black Hole Thermodynamics
Directory of Open Access Journals (Sweden)
Viktor G. Czinner
2017-02-01
Full Text Available We consider the thermodynamic and stability problem of Kerr black holes arising from the nonextensive/nonadditive nature of the Bekenstein–Hawking entropy formula. Nonadditive thermodynamics is often criticized by asserting that the zeroth law cannot be compatible with nonadditive composition rules, so in this work we follow the so-called formal logarithm method to derive an additive entropy function for Kerr black holes also satisfying the zeroth law’s requirement. Starting from the most general, equilibrium compatible, nonadditive entropy composition rule of Abe, we consider the simplest non-parametric approach that is generated by the explicit nonadditive form of the Bekenstein–Hawking formula. This analysis extends our previous results on the Schwarzschild case, and shows that the zeroth law-compatible temperature function in the model is independent of the mass–energy parameter of the black hole. By applying the Poincaré turning point method, we also study the thermodynamic stability problem in the system.
Thermodynamic modeling of algal cell–solid substrate interactions
International Nuclear Information System (INIS)
Cui, Yan; Yuan, Wenqiao
2013-01-01
Highlights: • A thermodynamic model was developed to simulate algal cell-substrate attachment. • The number of attached cells was positively correlated to work of attachment. • Algal cell attachment was determined by surface energies of cells and substrata. - Abstract: The process of microalgal cell attachment to solid-carrier surfaces was simulated through a thermodynamic model. The modeling results showed that, for most microbes, when the polar surface energy of the cell is smaller than that of water, cellular attachment would be more favorable on materials with higher dispersive surface energy but lower polar surface energy. If the polar surface energy of the cell is greater than that of water, more cell attachment would be expected on materials that are higher in both dispersive and polar surface energies. Modeling results qualitatively matched experimental data in the attachment of a freshwater alga, Scenedesmus dimorphus, and a marine alga, Nannochloropsis oculata, on five materials (nylon, stainless steel, polycarbonate, polypropylene, and glass). The model was also validated by published literature data on a wider variety of microbes and materials, indicating that the model developed can be applicable in designing, selecting, and matching algal strains and solid carrier materials to enhance cell attachment
Thermodynamical aspects of modeling the mechanical response of granular materials
International Nuclear Information System (INIS)
Elata, D.
1995-01-01
In many applications in rock physics, the material is treated as a continuum. By supplementing the related conservation laws with constitutive equations such as stress-strain relations, a well-posed problem can be formulated and solved. The stress-strain relations may be based on a combination of experimental data and a phenomenological or micromechanical model. If the model is physically sound and its parameters have a physical meaning, it can serve to predict the stress response of the material to unmeasured deformations, predict the stress response of other materials, and perhaps predict other categories of the mechanical response such as failure, permeability, and conductivity. However, it is essential that the model be consistent with all conservation laws and consistent with the second law of thermodynamics. Specifically, some models of the mechanical response of granular materials proposed in literature, are based on intergranular contact force-displacement laws that violate the second law of thermodynamics by permitting energy generation at no cost. This diminishes the usefulness of these models as it invalidates their predictive capabilities. [This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.
Enhanced thermodynamic modelling of a gamma-type Stirling engine
International Nuclear Information System (INIS)
Alfarawi, S.; AL-Dadah, R.; Mahmoud, S.
2016-01-01
Highlights: • Enhanced thermodynamic model for gamma-type Stirling engine was developed. • Validation against experiments was performed. • Influence of different parameters on engine performance was investigated. • Deeper insight into engine improvements was highlighted. • Effect of low temperature cooling on engine performance was addressed. - Abstract: Modelling can substantially contribute to the development of Stirling engines technology and help understanding the fundamental processes of the real cycle for further performance improvement. In the present work, an enhanced thermodynamic model for Gamma-type Stirling engine simulation was developed based on the reconfiguration of non-ideal adiabatic analysis. The developed model was validated against experimental measurements on Stirling engine prototype (ST05 CNC), available at University of Birmingham. Good agreement was found between the model and experiment in predicting the indicated power, shaft power and thermal efficiency at different operating conditions. A parametric study was carried out to investigate the effect of phase angle, gas type, regenerator matrix type and dead volume on engine performance. The feasibility of utilizing the stored cold energy of LN2 to maximize the shaft power was also presented. Results showed that shaft power can be significantly enhanced by 49% for helium and 35% for nitrogen when cooling temperature is lowered to −50 °C while heating temperature remains constant at 650 °C.
Nonequilibrium thermodynamic models and applications to hydrogen plasma
International Nuclear Information System (INIS)
Cho, K.Y.
1988-01-01
A generalized multithermal equilibrium (GMTE) thermodynamic model is developed and presented with applications to hydrogen. A new chemical equilibrium equation for GMTE is obtained without the ensemble temperature concept, used by a previous MTE model. The effects of the GMTE model on the derivation and calculation of the thermodynamic, transport, and radiative properties are presented and significant differences from local thermal equilibrium (LTE) and two temperature model are discussed. When the electron translational temperature (T e ) is higher than the translational temperature of the heavy particles, the effects of hydrogen molecular species to the properties are significant at high T e compared with LTE results. The density variations of minor species are orders of magnitude with kinetic nonequilibrium at a constant electron temperature. A collisional-radiative model is also developed with the GMTE chemical equilibrium equation to study the effects of radiative transfer and the ambipolar diffusion on the population distribution of the excited atoms. The nonlocal radiative transfer effect is parameterized by an absorption factor, which is defined as a ratio of the absorbed intensity to the spontaneous emission coefficient
ms 2: A molecular simulation tool for thermodynamic properties, release 3.0
Rutkai, Gábor; Köster, Andreas; Guevara-Carrion, Gabriela; Janzen, Tatjana; Schappals, Michael; Glass, Colin W.; Bernreuther, Martin; Wafai, Amer; Stephan, Simon; Kohns, Maximilian; Reiser, Steffen; Deublein, Stephan; Horsch, Martin; Hasse, Hans; Vrabec, Jadran
2017-12-01
A new version release (3.0) of the molecular simulation tool ms 2 (Deublein et al., 2011; Glass et al. 2014) is presented. Version 3.0 of ms 2 features two additional ensembles, i.e. microcanonical (NVE) and isobaric-isoenthalpic (NpH), various Helmholtz energy derivatives in the NVE ensemble, thermodynamic integration as a method for calculating the chemical potential, the osmotic pressure for calculating the activity of solvents, the six Maxwell-Stefan diffusion coefficients of quaternary mixtures, statistics for sampling hydrogen bonds, smooth-particle mesh Ewald summation as well as the ability to carry out molecular dynamics runs for an arbitrary number of state points in a single program execution.
A thermodynamic model for growth mechanisms of multiwall carbon nanotubes.
Energy Technology Data Exchange (ETDEWEB)
Kaatz, Forrest H.; Overmyer, Donald L.; Siegal, Michael P.
2006-02-01
Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830 C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60 eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.
Thermodynamic model for growth mechanisms of multiwall carbon nanotubes
Kaatz, F. H.; Siegal, M. P.; Overmyer, D. L.; Provencio, P. P.; Tallant, D. R.
2006-12-01
Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830°C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.
DEFF Research Database (Denmark)
Olesen, H. R.
1998-01-01
Proceedings of the Twenty-Second NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application, held June 6-10, 1997, in Clermont-Ferrand, France.......Proceedings of the Twenty-Second NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application, held June 6-10, 1997, in Clermont-Ferrand, France....
Thermodynamic model and parametric analysis of a tubular SOFC module
Campanari, Stefano
Solid oxide fuel cells (SOFCs) have been considered in the last years as one of the most promising technologies for very high-efficiency electric energy generation from natural gas, both with simple fuel cell plants and with integrated gas turbine-fuel cell systems. Among the SOFC technologies, tubular SOFC stacks with internal reforming have emerged as one of the most mature technology, with a serious potential for a future commercialization. In this paper, a thermodynamic model of a tubular SOFC stack, with natural gas feeding, internal reforming of hydrocarbons and internal air preheating is proposed. In the first section of the paper, the model is discussed in detail, analyzing its calculating equations and tracing its logical steps; the model is then calibrated on the available data for a recently demonstrated tubular SOFC prototype plant. In the second section of the paper, it is carried out a detailed parametric analysis of the stack working conditions, as a function of the main operating parameters. The discussion of the results of the thermodynamic and parametric analysis yields interesting considerations about partial load SOFC operation and load regulation, and about system design and integration with gas turbine cycles.
2005-01-01
Abstract An extremal principle is formulated for thermodynamic systems near equilibrium subjected to various external conditions. It is shown that the principle describes unambiguously the kinetics of the thermodynamic system and replaces classical phenomenological equations. The global formulation of the principle makes it possible I) to introduce discrete characteristic parameters for the proper description of the state and evolution of the system, II) to take into account constr...
Thermodynamic Modeling of Natural Gas Systems Containing Water
DEFF Research Database (Denmark)
Karakatsani, Eirini K.; Kontogeorgis, Georgios M.
2013-01-01
As the need for dew point specifications remains very urgent in the natural gas industry, the development of accurate thermodynamic models, which will match experimental data and will allow reliable extrapolations, is needed. Accurate predictions of the gas phase water content in equilibrium...... with a heavy phase were previously obtained using cubic plus association (CPA) coupled with a solid phase model in the case of hydrates, for the binary systems of water–methane and water–nitrogen and a few natural gas mixtures. In this work, CPA is being validated against new experimental data, both water...... content and phase equilibrium data, and solid model parameters are being estimated for four natural gas main components (methane, ethane, propane, and carbon dioxide). Different tests for the solid model parameters are reported, including vapor-hydrate-equilibria (VHE) and liquid-hydrate-equilibria (LHE...
A thermodynamic counterpart of the Axelrod model of social influence: The one-dimensional case
Gandica, Y.; Medina, E.; Bonalde, I.
2013-12-01
We propose a thermodynamic version of the Axelrod model of social influence. In one-dimensional (1D) lattices, the thermodynamic model becomes a coupled Potts model with a bonding interaction that increases with the site matching traits. We analytically calculate thermodynamic and critical properties for a 1D system and show that an order-disorder phase transition only occurs at T=0 independent of the number of cultural traits q and features F. The 1D thermodynamic Axelrod model belongs to the same universality class of the Ising and Potts models, notwithstanding the increase of the internal dimension of the local degree of freedom and the state-dependent bonding interaction. We suggest a unifying proposal to compare exponents across different discrete 1D models. The comparison with our Hamiltonian description reveals that in the thermodynamic limit the original out-of-equilibrium 1D Axelrod model with noise behaves like an ordinary thermodynamic 1D interacting particle system.
Thermodynamic study on some alkanediol solutions: Measurement and modeling
International Nuclear Information System (INIS)
Moosavi, Mehrdad; Motahari, Ahmad; Omrani, Abdollah; Rostami, Abbas Ali
2013-01-01
Highlights: • Measuring densities and viscosities for binary mixtures of some alkanediols. • Finding excess molar volume, partial molar volume and thermal expansion coefficient. • Fitting excess molar volume values with PFP and Redlich–Kister polynomial equations. • Deducing excess Gibbs free energy of activation and other thermodynamic parameters. • Predicting viscosity values with different single parameter semi empirical equations. - Abstract: The densities ρ and viscosities η of 1,2-ethanediol with 1,2-propanediol or 1,3-propanediol, and 1,2-propanediol with 1,3-propanediol binary liquid mixtures over the entire concentration range at temperatures (298.15 to 308.15) K with 5 K interval were measured. The experimental data were used to calculate the excess molar volume V m E , partial molar volume V ¯ m,i , partial molar volume at infinite dilution V ¯ i ∞ , apparent molar volume V φi , coefficient of thermal expansion α p , excess coefficient of thermal expansion α p E , excess viscosity η E , excess Gibbs energy of activation ΔG *E , and other thermodynamic parameters. A Redlich–Kister equation and Prigogine–Flory–Patterson (PFP) model was applied to correlate the excess molar volume results. Moreover, the viscosity data were correlated with the Grunberg–Nissan, Tamura–Kurata, Hind–Ubbelohde and Katti–Chaudhary equations. Good agreement was found between experimental data and modeling results
DEFF Research Database (Denmark)
Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj
2015-01-01
Aqueous MDEA is the most commonly used solvent for H2S removal from natural gas. A reliable thermodynamic model is required for the proper design of natural gas sweetening processes. In this study, a rigorous thermodynamic model is developed to represent properties of the H2S-MDEA-H2O ternary...... system. The Extended UNIQUAC model is used to represent the system behavior. The model is created based on models for the constituent binary subsystems. The developed model provides accurate representation of VLE and heat of absorption for the studied system and subsystem in the temperature range of 0...
Experimental measurements and thermodynamic modeling of refrigerant hydrates dissociation conditions
International Nuclear Information System (INIS)
Hashemi, Hamed; Babaee, Saeedeh; Mohammadi, Amir H.; Naidoo, Paramespri; Ramjugernath, Deresh
2015-01-01
Highlights: • Dissociation conditions of refrigerant hydrates are studied experimentally and theoretically. • Refrigerants R23, R134a, R125a, R22, R410A, R407C and R507C are studied experimentally. • A thermodynamic model able to predict refrigerant hydrates dissociation conditions is proposed. • The results show good agreement between the experimental and predicted values. - Abstract: This study aims to investigate dissociation conditions of refrigerant hydrates both experimentally and theoretically. For this purpose, dissociation conditions of refrigerants R23, R134a, R125a, R22, R410A, R407C and R507C have been measured experimentally. A thermodynamic model that is able to predict refrigerant hydrates dissociation conditions in the various phase equilibrium regions has been proposed as well. Refrigerants modeled in this study include pure refrigerants: R11, R12, R13, R22, R23, R32, R134a, R141b, R143a, R125a, R152a, and mixed refrigerants: R11 + R12, R11 + R114, R12 + R114, R32 + R125a + R134a (R407C), R32 + R125a (R410A). For the modeling of the fluid and hydrate phases, the Peng-Robinson equation of state modified by Stryjek and Vera and the MHV2 G E -EoS mixing rule along with the UNIFAC (original) activity coefficient and van der Waals–Platteeuw (vdW–P) models were employed. The results show good agreement between the experimental and predicted values
Thermodynamic Development of Corrosion Rate Modeling in Iron Phosphate Glasses
Energy Technology Data Exchange (ETDEWEB)
Schlesinger, Mark [Missouri Univ. of Science and Technology, Rolla, MO (United States); Brow, Richard [Missouri Univ. of Science and Technology, Rolla, MO (United States)
2011-10-31
A two-year research program investigated links between the thermodynamic properties of phosphate glasses and their corrosion rates in different solutions. Glasses in the Na_{2}O-CaO-P_{2}O_{5} and Na_{2}O-Fe_{2}O_{3}-PO_{5} systems were prepared and characterized. These glasses were then exposed in bulk and powder form to acid (0.1M HCl), basic (0.1M KOH) and neutral (deionized water) solutions at varying exposure times and temperatures. Analysis of the solution and the glass after exposure determined the rate and type of corrosion that occurred. Simultaneously, efforts were made to determine the thermodynamic properties of solid iron phosphate compounds. This included measurement of low temperature (5-300 K) heat capacities, measured at Brigham Young University; the attempted use of a Parr calorimeter to measure ambient temperature enthalpies of formation; and attempted measurement of temperature heat capacities. Only the first of the three tasks was successfully accomplished. In lieu of experimental measurement of enthalpies of formation, first-principles calculation of enthalpies of formation was performed at Missouri S&T; these results will be used in subsequent modeling efforts.
Pernin, Jérôme; Vrac, Mathieu; Crevoisier, Cyril; Chédin, Alain
2017-04-01
Air mass classification has become an important area in synoptic climatology, simplifying the complexity of the atmosphere by dividing the atmosphere into discrete similar thermodynamic patterns. However, the constant growth of atmospheric databases in both size and complexity implies the need to develop new adaptive classifications. Here, we propose a robust unsupervised and supervised classification methodology of a large thermodynamic dataset, on a global scale and over several years, into discrete air mass groups homogeneous in both temperature and humidity that also provides underlying probability laws. Temperature and humidity at different pressure levels are aggregated into a set of cumulative distribution function (CDF) values instead of classical ones. The method is based on a Gaussian mixture model and uses the expectation-maximization (EM) algorithm to estimate the parameters of the mixture. Spatially gridded thermodynamic profiles come from ECMWF reanalyses spanning the period 2000-2009. Different aspects are investigated, such as the sensitivity of the classification process to both temporal and spatial samplings of the training dataset. Comparisons of the classifications made either by the EM algorithm or by the widely used k-means algorithm show that the former can be viewed as a generalization of the latter. Moreover, the EM algorithm delivers, for each observation, the probabilities of belonging to each class, as well as the associated uncertainty. Finally, a decision tree is proposed as a tool for interpreting the different classes, highlighting the relative importance of temperature and humidity in the classification process.
de la Fuente, Alberto; Meruane, Carolina
2017-09-01
Altiplanic wetlands are unique ecosystems located in the elevated plateaus of Chile, Argentina, Peru, and Bolivia. These ecosystems are under threat due to changes in land use, groundwater extractions, and climate change that will modify the water balance through changes in precipitation and evaporation rates. Long-term prediction of the fate of aquatic ecosystems imposes computational constraints that make finding a solution impossible in some cases. In this article, we present a spectral model for long-term simulations of the thermodynamics of shallow wetlands in the limit case when the water depth tends to zero. This spectral model solves for water and sediment temperature, as well as heat, momentum, and mass exchanged with the atmosphere. The parameters of the model (water depth, thermal properties of the sediments, and surface albedo) and the atmospheric downscaling were calibrated using the MODIS product of the land surface temperature. Moreover, the performance of the daily evaporation rates predicted by the model was evaluated against daily pan evaporation data measured between 1964 and 2012. The spectral model was able to correctly represent both seasonal fluctuation and climatic trends observed in daily evaporation rates. It is concluded that the spectral model presented in this article is a suitable tool for assessing the global climate change effects on shallow wetlands whose thermodynamics is forced by heat exchanges with the atmosphere and modulated by the heat-reservoir role of the sediments.
International Nuclear Information System (INIS)
Garcia-Moliner, F.
1975-01-01
Basic thermodynamics of a system consisting of two bulk phases with an interface. Solid surfaces: general. Discussion of experimental data on surface tension and related concepts. Adsorption thermodynamics in the Gibbsian scheme. Adsorption on inert solid adsorbents. Systems with electrical charges: chemistry and thermodynamics of imperfect crystals. Thermodynamics of charged surfaces. Simple models of charge transfer chemisorption. Adsorption heat and related concepts. Surface phase transitions
DEFF Research Database (Denmark)
Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj
2015-01-01
A Thermodynamic model that can predict the behavior of the gas sweetening process over the applicable conditions is of vital importance in industry. In this work, Extended UNIQUAC model parameters optimized for the CO2-MDEA-H2O system are presented. Different types of experimental data consisting...... model accurately represents thermodynamic and thermal properties of the studied systems. The model parameters are valid in the temperature range from -15 to 200 °C, MDEA mass% of 5-75 and CO2 partial pressure of 0-6161.5 kPa....
Thermodynamic modelling and in-situ neutron diffraction investigation of the (Nd + Mg + Zn) system
International Nuclear Information System (INIS)
Zhu, Zhijun; Gharghouri, Michael A.; Pelton, Arthur D.
2016-01-01
Highlights: • All phase diagram and thermodynamic data critically assessed for the (Nd + Mg + Zn) system. • All phases described by optimised thermodynamic models. • In-situ neutron diffraction performed to identify phases and transition temperatures. • Assessments of other (RE + Mg + Zn) systems have been carried out simultaneously. • The final product is a thermodynamic database for multicomponent (Mg + RE + Zn) systems. - Abstract: All available phase diagram data for the (Nd + Mg + Zn) system were critically assessed. In-situ neutron diffraction (ND) experiments were performed on selected samples to identify phases and transition temperatures. A critical thermodynamic evaluation and optimization of the (Nd + Mg + Zn) system was carried out and model parameters for the thermodynamic properties of all phases were obtained. The phase transformation behaviour of selected samples was well resolved from the ND experiments and experimental values were used to refine the thermodynamic model parameters.
Thermodynamic modelling and in-situ neutron diffraction investigation of the (Ce + Mg + Zn) system
International Nuclear Information System (INIS)
Zhu, Zhijun; Gharghouri, Michael A.; Medraj, Mamoun; Lee, Soo Yeol; Pelton, Arthur D.
2016-01-01
Highlights: • All phase diagram and thermodynamic data critically assessed for the (Ce + Mg + Zn) system. • All phases described by optimized thermodynamic models. • In-situ neutron diffraction performed to identify phases and transition temperatures. • Assessments of other (RE + Mg + Zn) systems have been carried out simultaneously. • The final product is a thermodynamic database for multicomponent (Mg + RE + Zn) systems. - Abstract: All available phase diagram data for the (Ce + Mg + Zn) system were critically assessed. In-situ neutron diffraction (ND) experiments were performed on selected samples to identify phases and transition temperatures. A critical thermodynamic evaluation and optimization of the (Ce + Mg + Zn) system were carried out and model parameters for the thermodynamic properties of all phases were obtained. The phase transformation behaviour of selected samples was well resolved from the ND experiments and experimental data were used to refine the thermodynamic model parameters.
Thermodynamics of bread baking: A two-state model
Zürcher, Ulrich
2014-03-01
Bread baking can be viewed as a complex physico-chemical process. It is governed by transport of heat and is accompanied by changes such as gelation of starch, the expansion of air cells within dough, and others. We focus on the thermodynamics of baking and investigate the heat flow through dough and find that the evaporation of excess water in dough is the rate-limiting step. We consider a simplified one-dimensional model of bread, treating the excess water content as a two-state variable that is zero for baked bread and a fixed constant for unbaked dough. We arrive at a system of coupled, nonlinear ordinary differential equations, which are solved using a standard Runge-Kutta integration method. The calculated baking times are consistent with common baking experience.
A parametric model for the global thermodynamic behavior of fluids in the critical region
International Nuclear Information System (INIS)
Luettmer-Strathmann, J.; Tang, S.; Sengers, J.V.
1992-01-01
The asymptotic thermodynamic behavior of fluids near the critical point is described by scaling laws with universal scaling functions that can be represented by parametric equations. In this paper, we derive a more general parametric model that incorporates the crossover from singular thermodynamic behavior near the critical point to regular classical thermodynamic behavior far away from the critical point. Using ethane as an example, we show that such a parametric crossover model yields an accurate representation of the thermodynamic properties of fluids in a large region around the critical point
THERMODYNAMIC MODEL OF THE CYCLE OF SPARK IGNITION ENGINE WITH EXHAUST GAS RECIRCULATION
Öğüçlü, Özer
2015-01-01
A thermodynamic model has been developed and applied to predict the emission levels and performance of a spark ignition engine with using Exhaust Gas Recirculation (EGR) gas. The model simulates the full thermodynamic cycle of the engine and includes heat transfer, combustion, gas exchange process, thermal dissociation of water and carbon dioxide, and chemical equilibrium.
A thermodynamic model of microtubule assembly and disassembly.
Directory of Open Access Journals (Sweden)
Bernard M A G Piette
Full Text Available Microtubules are self-assembling polymers whose dynamics are essential for the normal function of cellular processes including chromosome separation and cytokinesis. Therefore understanding what factors effect microtubule growth is fundamental to our understanding of the control of microtubule based processes. An important factor that determines the status of a microtubule, whether it is growing or shrinking, is the length of the GTP tubulin microtubule cap. Here, we derive a Monte Carlo model of the assembly and disassembly of microtubules. We use thermodynamic laws to reduce the number of parameters of our model and, in particular, we take into account the contribution of water to the entropy of the system. We fit all parameters of the model from published experimental data using the GTP tubulin dimer attachment rate and the lateral and longitudinal binding energies of GTP and GDP tubulin dimers at both ends. Also we calculate and incorporate the GTP hydrolysis rate. We have applied our model and can mimic published experimental data, which formerly suggested a single layer GTP tubulin dimer microtubule cap, to show that these data demonstrate that the GTP cap can fluctuate and can be several microns long.
Thermodynamic modeling of the Pt-Zr system
International Nuclear Information System (INIS)
Gao Yongliang; Guo Cuiping; Li Changrong; Du Zhenmin
2010-01-01
By means of the CALPHAD (CALculation of PHAse Diagram) technique, the Pt-Zr system was critically assessed. The solution phases (liquid, bcc, fcc and hcp) are described with the substitutional model. The intermetallic compounds Pt 4 Zr, Pt 4 Zr 3 , αPtZr and Pt 3 Zr 5 are treated as the formula (Pt,Zr) m (Pt,Zr) n by a two-sublattice model with the elements Pt and Zr on the first and the second sublattices, respectively. A two-sublattice model (Pt,Zr) 0.5 (Pt,Zr) 0.5 is applied to describe the compound βPtZr with CsCl-type structure (B2) in order to cope with the order-disorder transition between bcc solution (A2) and βPtZr (B2). Another two-sublattice model (Pt,Zr) 0.75 (Pt,Zr) 0.25 with Ni 3 Ti-type structure (D0 24 ) is applied to describe the compound Pt 3 Zr in order to cope with the order-disorder transition between hexagonal close-packed (A3) and Pt 3 Zr (D0 24 ). The compound Pt 10 Zr 7 is treated as a stoichiometric compound. A set of self-consistent thermodynamic parameters of the Pt-Zr system was obtained. (orig.)
Thermodynamic modeling of iodine and selenium retention in solutions with high salinity
International Nuclear Information System (INIS)
Hagemann, Sven; Moog, Helge C.; Herbert, Horst-Juergen; Erich, Agathe
2012-04-01
The report on iodine and selenium retention in saline solutions includes the following chapters: (1) Introduction and scope of the work. (2) Actual status of knowledge. (3) Experimental and numerical models. (4) Thermodynamic properties of selenite and hydrogen selenite in solutions of oceanic salts. (5) Thermodynamic properties of selenate in solutions of oceanic salts. (6) Thermodynamic properties of iodide in solutions of oceanic salts. (7) Experimental studies on the retention of iodine and selenium in selected sorbents. (8) Summary and conclusions.
Critical, statistical, and thermodynamical properties of lattice models
Energy Technology Data Exchange (ETDEWEB)
Varma, Vipin Kerala
2013-10-15
In this thesis we investigate zero temperature and low temperature properties - critical, statistical and thermodynamical - of lattice models in the contexts of bosonic cold atom systems, magnetic materials, and non-interacting particles on various lattice geometries. We study quantum phase transitions in the Bose-Hubbard model with higher body interactions, as relevant for optical lattice experiments of strongly interacting bosons, in one and two dimensions; the universality of the Mott insulator to superfluid transition is found to remain unchanged for even large three body interaction strengths. A systematic renormalization procedure is formulated to fully re-sum these higher (three and four) body interactions into the two body terms. In the strongly repulsive limit, we analyse the zero and low temperature physics of interacting hard-core bosons on the kagome lattice at various fillings. Evidence for a disordered phase in the Ising limit of the model is presented; in the strong coupling limit, the transition between the valence bond solid and the superfluid is argued to be first order at the tip of the solid lobe.
Critical, statistical, and thermodynamical properties of lattice models
International Nuclear Information System (INIS)
Varma, Vipin Kerala
2013-10-01
In this thesis we investigate zero temperature and low temperature properties - critical, statistical and thermodynamical - of lattice models in the contexts of bosonic cold atom systems, magnetic materials, and non-interacting particles on various lattice geometries. We study quantum phase transitions in the Bose-Hubbard model with higher body interactions, as relevant for optical lattice experiments of strongly interacting bosons, in one and two dimensions; the universality of the Mott insulator to superfluid transition is found to remain unchanged for even large three body interaction strengths. A systematic renormalization procedure is formulated to fully re-sum these higher (three and four) body interactions into the two body terms. In the strongly repulsive limit, we analyse the zero and low temperature physics of interacting hard-core bosons on the kagome lattice at various fillings. Evidence for a disordered phase in the Ising limit of the model is presented; in the strong coupling limit, the transition between the valence bond solid and the superfluid is argued to be first order at the tip of the solid lobe.
Bayesian Regression of Thermodynamic Models of Redox Active Materials
Energy Technology Data Exchange (ETDEWEB)
Johnston, Katherine [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-09-01
Finding a suitable functional redox material is a critical challenge to achieving scalable, economically viable technologies for storing concentrated solar energy in the form of a defected oxide. Demonstrating e ectiveness for thermal storage or solar fuel is largely accomplished by using a thermodynamic model derived from experimental data. The purpose of this project is to test the accuracy of our regression model on representative data sets. Determining the accuracy of the model includes parameter tting the model to the data, comparing the model using di erent numbers of param- eters, and analyzing the entropy and enthalpy calculated from the model. Three data sets were considered in this project: two demonstrating materials for solar fuels by wa- ter splitting and the other of a material for thermal storage. Using Bayesian Inference and Markov Chain Monte Carlo (MCMC), parameter estimation was preformed on the three data sets. Good results were achieved, except some there was some deviations on the edges of the data input ranges. The evidence values were then calculated in a variety of ways and used to compare models with di erent number of parameters. It was believed that at least one of the parameters was unnecessary and comparing evidence values demonstrated that the parameter was need on one data set and not signi cantly helpful on another. The entropy was calculated by taking the derivative in one variable and integrating over another. and its uncertainty was also calculated by evaluating the entropy over multiple MCMC samples. Afterwards, all the parts were written up as a tutorial for the Uncertainty Quanti cation Toolkit (UQTk).
Makahinda, T.
2018-02-01
The purpose of this research is to find out the effect of learning model based on technology and assessment technique toward thermodynamic achievement by controlling students intelligence. This research is an experimental research. The sample is taken through cluster random sampling with the total respondent of 80 students. The result of the research shows that the result of learning of thermodynamics of students who taught the learning model of environmental utilization is higher than the learning result of student thermodynamics taught by simulation animation, after controlling student intelligence. There is influence of student interaction, and the subject between models of technology-based learning with assessment technique to student learning result of Thermodynamics, after controlling student intelligence. Based on the finding in the lecture then should be used a thermodynamic model of the learning environment with the use of project assessment technique.
Afkhamipour, Morteza; Mofarahi, Masoud; Borhani, Tohid Nejad Ghaffar; Zanganeh, Masoud
2018-03-01
In this study, artificial neural network (ANN) and thermodynamic models were developed for prediction of the heat capacity ( C P ) of amine-based solvents. For ANN model, independent variables such as concentration, temperature, molecular weight and CO2 loading of amine were selected as the inputs of the model. The significance of the input variables of the ANN model on the C P values was investigated statistically by analyzing of correlation matrix. A thermodynamic model based on the Redlich-Kister equation was used to correlate the excess molar heat capacity ({C}_P^E) data as function of temperature. In addition, the effects of temperature and CO2 loading at different concentrations of conventional amines on the C P values were investigated. Both models were validated against experimental data and very good results were obtained between two mentioned models and experimental data of C P collected from various literatures. The AARD between ANN model results and experimental data of C P for 47 systems of amine-based solvents studied was 4.3%. For conventional amines, the AARD for ANN model and thermodynamic model in comparison with experimental data were 0.59% and 0.57%, respectively. The results showed that both ANN and Redlich-Kister models can be used as a practical tool for simulation and designing of CO2 removal processes by using amine solutions.
Thermodynamic Property Model of Wide-Fluid Phase Propane
Directory of Open Access Journals (Sweden)
I Made Astina
2007-05-01
Full Text Available A new thermodynamic property model for propane is expressed in form of the Helmholtz free energy function. It consists of eight terms of the ideal-gas part and eighteen terms of the residual part. Accurate experimental data of fluid properties and theoretical approach from the intermolecular potential were simultaneously considered in the development to insure accuracy and to improve reliability of the equation of state over wide range of pressures and temperatures. Based on the state range of experimental data used in the model development, the validity range is judged from the triple-point of 85.48 K to temperature of 450 K and pressure up to 60 MPa. The uncertainties with respect to different properties are estimated to be 0.03% in ideal-gas isobaric specific heat, 0.2% in liquid phase density, 0.3% in gaseous phase density 1% in specific heats, 0.1% in vapor-pressure except at very low temperatures, 0.05% in saturated-liquid density, 0.02% in speed of sound of the gaseous phase and 1% in speed of sound of the liquid phase.
Le, Vu H.; Buscaglia, Robert; Chaires, Jonathan B.; Lewis, Edwin A.
2013-01-01
Isothermal Titration Calorimetry, ITC, is a powerful technique that can be used to estimate a complete set of thermodynamic parameters (e.g. Keq (or ΔG), ΔH, ΔS, and n) for a ligand binding interaction described by a thermodynamic model. Thermodynamic models are constructed by combination of equilibrium constant, mass balance, and charge balance equations for the system under study. Commercial ITC instruments are supplied with software that includes a number of simple interaction models, for example one binding site, two binding sites, sequential sites, and n-independent binding sites. More complex models for example, three or more binding sites, one site with multiple binding mechanisms, linked equilibria, or equilibria involving macromolecular conformational selection through ligand binding need to be developed on a case by case basis by the ITC user. In this paper we provide an algorithm (and a link to our MATLAB program) for the non-linear regression analysis of a multiple binding site model with up to four overlapping binding equilibria. Error analysis demonstrates that fitting ITC data for multiple parameters (e.g. up to nine parameters in the three binding site model) yields thermodynamic parameters with acceptable accuracy. PMID:23262283
Directory of Open Access Journals (Sweden)
Janssen Stefan
2011-11-01
Full Text Available Abstract Background Many bioinformatics tools for RNA secondary structure analysis are based on a thermodynamic model of RNA folding. They predict a single, "optimal" structure by free energy minimization, they enumerate near-optimal structures, they compute base pair probabilities and dot plots, representative structures of different abstract shapes, or Boltzmann probabilities of structures and shapes. Although all programs refer to the same physical model, they implement it with considerable variation for different tasks, and little is known about the effects of heuristic assumptions and model simplifications used by the programs on the outcome of the analysis. Results We extract four different models of the thermodynamic folding space which underlie the programs RNAFOLD, RNASHAPES, and RNASUBOPT. Their differences lie within the details of the energy model and the granularity of the folding space. We implement probabilistic shape analysis for all models, and introduce the shape probability shift as a robust measure of model similarity. Using four data sets derived from experimentally solved structures, we provide a quantitative evaluation of the model differences. Conclusions We find that search space granularity affects the computed shape probabilities less than the over- or underapproximation of free energy by a simplified energy model. Still, the approximations perform similar enough to implementations of the full model to justify their continued use in settings where computational constraints call for simpler algorithms. On the side, we observe that the rarely used level 2 shapes, which predict the complete arrangement of helices, multiloops, internal loops and bulges, include the "true" shape in a rather small number of predicted high probability shapes. This calls for an investigation of new strategies to extract high probability members from the (very large level 2 shape space of an RNA sequence. We provide implementations of all four
Thermodynamic Modelling of an Ejector with Compressible Flow by a One-Dimensional Approach
Directory of Open Access Journals (Sweden)
Claude Chacoux
2012-03-01
Full Text Available The purpose of this study is the dimensioning of the cylindrical mixing chamber of a compressible fluid ejector used in particular in sugar refineries for degraded vapor re‑compression at the calandria exit, during the evaporation phase. The method used, known as the “integral” or “thermodynamic model”, is based on the model of the one‑dimensional isentropic flow of perfect gases with the addition of a model of losses. Characteristic curves and envelope curves are plotted. The latter are an interesting tool from which the characteristic dimensions of the ejector can be rapidly obtained for preliminary dimensioning (for an initial contact with a customer for example. These ejectors, which were specifically designed for the process rather than selected from a catalog of standard devices, will promote energy saving.
A new self-consistent model for thermodynamics of binary solutions
Czech Academy of Sciences Publication Activity Database
Svoboda, Jiří; Shan, Y. V.; Fischer, F. D.
2015-01-01
Roč. 108, NOV (2015), s. 27-30 ISSN 1359-6462 R&D Projects: GA ČR(CZ) GA14-24252S Institutional support: RVO:68081723 Keywords : Thermodynamics * Analytical methods * CALPHAD * Phase diagram * Self-consistent model Subject RIV: BJ - Thermodynamics Impact factor: 3.305, year: 2015
Experimental study and thermodynamic modelling of the B-Fe-Mn ternary system
Czech Academy of Sciences Publication Activity Database
Repovský, P.; Homolová, V.; Čiripová, L.; Kroupa, Aleš; Zemanová, Adéla
2016-01-01
Roč. 55, DEC (2016), s. 252-259 ISSN 0364-5916 R&D Projects: GA ČR GA14-15576S Institutional support: RVO:68081723 Keywords : thermodynamic modelling * phase diagram * borides Subject RIV: BJ - Thermodynamic s Impact factor: 1.600, year: 2016
A Thermodynamically-consistent FBA-based Approach to Biogeochemical Reaction Modeling
Shapiro, B.; Jin, Q.
2015-12-01
Microbial rates are critical to understanding biogeochemical processes in natural environments. Recently, flux balance analysis (FBA) has been applied to predict microbial rates in aquifers and other settings. FBA is a genome-scale constraint-based modeling approach that computes metabolic rates and other phenotypes of microorganisms. This approach requires a prior knowledge of substrate uptake rates, which is not available for most natural microbes. Here we propose to constrain substrate uptake rates on the basis of microbial kinetics. Specifically, we calculate rates of respiration (and fermentation) using a revised Monod equation; this equation accounts for both the kinetics and thermodynamics of microbial catabolism. Substrate uptake rates are then computed from the rates of respiration, and applied to FBA to predict rates of microbial growth. We implemented this method by linking two software tools, PHREEQC and COBRA Toolbox. We applied this method to acetotrophic methanogenesis by Methanosarcina barkeri, and compared the simulation results to previous laboratory observations. The new method constrains acetate uptake by accounting for the kinetics and thermodynamics of methanogenesis, and predicted well the observations of previous experiments. In comparison, traditional methods of dynamic-FBA constrain acetate uptake on the basis of enzyme kinetics, and failed to reproduce the experimental results. These results show that microbial rate laws may provide a better constraint than enzyme kinetics for applying FBA to biogeochemical reaction modeling.
Nathoo, Jeeten; Randall, Dyllon Garth
2016-01-01
Membrane distillation (MD) could be applicable in zero liquid discharge applications. This is due to the fact that MD is applicable at high salinity ranges which are generally outside the scope of reverse osmosis (RO) applications, although this requires proper management of precipitating salts to avoid membrane fouling. One way of managing these salts is with MD crystallisation (MDC). This paper focuses on the applicability of MDC for the treatment of mining wastewater by thermodynamically modelling the aqueous chemistry of the process at different temperatures. The paper is based on the typical brine generated from an RO process in the South African coal mining industry and investigates the effect water recovery and operating temperature have on the salts that are predicted to crystallise out, the sequence in which they will crystallise out and purities as a function of the water recovery. The study confirmed the efficacy of using thermodynamic modelling as a tool for investigating and predicting the crystallisation aspects of the MDC process. The key finding from this work was that, for an MDC process, a purer product can be obtained at higher operating temperatures and recoveries because of the inverse solubility of calcium sulphate.
Integrating a Decision Management Tool with UML Modeling Tools
DEFF Research Database (Denmark)
Könemann, Patrick
the development process. In this report, we propose an integration of a decision management and a UML-based modeling tool, based on use cases we distill from a case study: the modeling tool shall show all decisions related to a model and allow its users to extend or update them; the decision management tool shall......Numerous design decisions are made while developing software systems, which influence the architecture of these systems as well as following decisions. A number of decision management tools already exist for capturing, documenting, and maintaining design decisions, but also for guiding developers...... trigger the modeling tool to realize design decisions in the models. We define tool-independent concepts and architecture building blocks supporting these use cases and present how they can be implemented in the IBM Rational Software Modeler and Architectural Decision Knowledge Wiki. This seamless...
Thermodynamic Modelling of Supersonic Gas Ejector with Droplets
Directory of Open Access Journals (Sweden)
Sergio Croquer
2017-10-01
Full Text Available This study presents a thermodynamic model for determining the entrainment ratio and double choke limiting pressure of supersonic ejectors within the context of heat driven refrigeration cycles, with and without droplet injection, at the constant area section of the device. Input data include the inlet operating conditions and key geometry parameters (primary throat, mixing section and diffuser outlet diameter, whereas output information includes the ejector entrainment ratio, maximum double choke compression ratio, ejector efficiency, exergy efficiency and exergy destruction index. In single-phase operation, the ejector entrainment ratio and double choke limiting pressure are determined with a mean accuracy of 18 % and 2.5 % , respectively. In two-phase operation, the choked mass flow rate across convergent-divergent nozzles is estimated with a deviation of 10 % . An analysis on the effect of droplet injection confirms the hypothesis that droplet injection reduces by 8 % the pressure and Mach number jumps associated with shock waves occuring at the end of the constant area section. Nonetheless, other factors such as the mixing of the droplets with the main flow are introduced, resulting in an overall reduction by 11 % of the ejector efficiency and by 15 % of the exergy efficiency.
On Thermodynamics Problems in the Single-Phase-Lagging Heat Conduction Model
Directory of Open Access Journals (Sweden)
Shu-Nan Li
2016-11-01
Full Text Available Thermodynamics problems for the single-phase-lagging (SPL model have not been much studied. In this paper, the violation of the second law of thermodynamics by the SPL model is studied from two perspectives, which are the negative entropy production rate and breaking equilibrium spontaneously. The methods for the SPL model to avoid the negative entropy production rate are proposed, which are extended irreversible thermodynamics and the thermal relaxation time. Modifying the entropy production rate positive or zero is not enough to avoid the violation of the second law of thermodynamics for the SPL model, because the SPL model could cause breaking equilibrium spontaneously in some special circumstances. As comparison, it is shown that Fourier’s law and the CV model cannot break equilibrium spontaneously by analyzing mathematical energy integral.
Energy Technology Data Exchange (ETDEWEB)
Li, Yulan; Hu, Shenyang Y.; Sun, Xin; Khaleel, Mohammad A.
2011-06-15
Microstructure evolution kinetics in irradiated materials has strongly spatial correlation. For example, void and second phases prefer to nucleate and grow at pre-existing defects such as dislocations, grain boundaries, and cracks. Inhomogeneous microstructure evolution results in inhomogeneity of microstructure and thermo-mechanical properties. Therefore, the simulation capability for predicting three dimensional (3-D) microstructure evolution kinetics and its subsequent impact on material properties and performance is crucial for scientific design of advanced nuclear materials and optimal operation conditions in order to reduce uncertainty in operational and safety margins. Very recently the meso-scale phase-field (PF) method has been used to predict gas bubble evolution, void swelling, void lattice formation and void migration in irradiated materials,. Although most results of phase-field simulations are qualitative due to the lake of accurate thermodynamic and kinetic properties of defects, possible missing of important kinetic properties and processes, and the capability of current codes and computers for large time and length scale modeling, the simulations demonstrate that PF method is a promising simulation tool for predicting 3-D heterogeneous microstructure and property evolution, and providing microstructure evolution kinetics for higher scale level simulations of microstructure and property evolution such as mean field methods. This report consists of two parts. In part I, we will present a new phase-field model for predicting interstitial loop growth kinetics in irradiated materials. The effect of defect (vacancy/interstitial) generation, diffusion and recombination, sink strength, long-range elastic interaction, inhomogeneous and anisotropic mobility on microstructure evolution kinetics is taken into account in the model. The model is used to study the effect of elastic interaction on interstitial loop growth kinetics, the interstitial flux, and sink
Thermodynamic modeling of the Ti-Al-Cr ternary system
International Nuclear Information System (INIS)
Chen Leyi; Qiu Aitao; Liu Lanjie; Jiang Ming; Lu Xionggang; Li Chonghe
2011-01-01
Research highlights: → The full experimental results of the Ti-Al-Cr ternary system and its sub-binary systems are reviewed and analysed in detail. → Based on the latest thermodynamic assessments of the Ti-Al, Ti-Cr and Al-Cr systems and the ternary experimental data in literature, the thermodynamic parameters of the Ti-Al-Cr ternary system are fully assessed by the Calphad method. → The transformation of disorder to order (bcc a 2 to B2) and the new ternary compound L 12T i 25 Cr 8 Al 67 are considered in this work. - Abstract: The Ti-Al-Cr ternary system is one of the most important systems to studying the titanium alloys. Some experimental data of this ternary system are available and a few partial thermodynamic assessments are reported. However, no full thermodynamic descriptions were published. In this study, the previous work on the Ti-Al-Cr system and its related binary systems are reviewed. Based on the thermodynamic descriptions of the Ti-Al, Ti-Cr and Al-Cr systems and the ternary experimental data in literature, the Ti-Al-Cr ternary system is assessed by means of the Calphad method. Several isothermal sections from 1073 K to 1573 K and some invariant reactions are calculated, which are in good agreement with the most of the experimental results.
Thermodynamic modeling of the power plant based on the SOFC with internal steam reforming of methane
International Nuclear Information System (INIS)
Ivanov, Peter
2007-01-01
Mathematical model based on the thermodynamic modeling of gaseous mixtures is developed for SOFC with internal steam reforming of methane. Macroscopic porous-electrode theory, including non-linear kinetics and gas-phase diffusion, is used to calculate the reforming reaction and the concentration polarization. Provided the data concerning properties and costs of materials the model is fit for wide range of parametric analysis of thermodynamic cycles including SOFC
Behaviour of defective CANDU fuel: fuel oxidation kinetic and thermodynamic modelling
International Nuclear Information System (INIS)
Higgs, J.
2005-01-01
The thermal performance of operating CANDU fuel under defect conditions is affected by the ingress of heavy water into the fuel element. A mechanistic model has been developed to predict the extent of fuel oxidation in defective fuel and its affect on fuel thermal performance. A thermodynamic treatment of such oxidized fuel has been performed as a basis for the boundary conditions in the kinetic model. Both the kinetic and thermodynamic models have been benchmarked against recent experimental work. (author)
Donnet, Marcel; Bowen, Paul; Lemaître, Jacques
2009-12-15
Thermodynamic solubility calculations are normally only related to thermodynamic equilibria in solution. In this paper, we extend the use of such solubility calculations to help elucidate possible precipitation reaction pathways during the entire reaction. We also estimate the interfacial energy of particles using only solubility data by a modification of Mersmann's approach. We have carried this out by considering precipitation reactions as a succession of small quasi-equilibrium states. Thus possible equilibrium precipitation pathways can be evaluated by calculating the evolution of surface charge, particle size and/or interfacial energy during the ongoing reaction. The approach includes the use of the Kelvin's law to express the influence of particle size on the solubility constant of precipitates, the use of Nernst's law to calculate surface potentials from solubility calculations and relate this to experimentally measured zeta potentials. Calcium carbonate precipitation and zeta potential measurements of well characterised high purity calcite have been used as a model system to validate the calculated values. The clarification of the change in zeta potential on titration illustrates the power of this approach as a tool for reaction pathway prediction and hence knowledge based tailoring of precipitation reactions.
Quality Systems. A Thermodynamics-Related Interpretive Model
Directory of Open Access Journals (Sweden)
Stefano A. Lollai
2017-08-01
Full Text Available In the present paper, a Quality Systems Theory is presented. Certifiable Quality Systems are treated and interpreted in accordance with a Thermodynamics-based approach. Analysis is also conducted on the relationship between Quality Management Systems (QMSs and systems theories. A measure of entropy is proposed for QMSs, including a virtual document entropy and an entropy linked to processes and organisation. QMSs are also interpreted in light of Cybernetics, and interrelations between Information Theory and quality are also highlighted. A measure for the information content of quality documents is proposed. Such parameters can be used as adequacy indices for QMSs. From the discussed approach, suggestions for organising QMSs are also derived. Further interpretive thermodynamic-based criteria for QMSs are also proposed. The work represents the first attempt to treat quality organisational systems according to a thermodynamics-related approach. At this stage, no data are available to compare statements in the paper.
Modeling thermodynamic distance, curvature and fluctuations a geometric approach
Badescu, Viorel
2016-01-01
This textbook aims to briefly outline the main directions in which the geometrization of thermodynamics has been developed in the last decades. The textbook is accessible to people trained in thermal sciences but not necessarily with solid formation in mathematics. For this, in the first chapters a summary of the main mathematical concepts is made. In some sense, this makes the textbook self-consistent. The rest of the textbook consists of a collection of results previously obtained in this young branch of thermodynamics. The manner of presentation used throughout the textbook is adapted for ease of access of readers with education in natural and technical sciences.
Abnormal grain growth: a non-equilibrium thermodynamic model for multi-grain binary systems
Czech Academy of Sciences Publication Activity Database
Svoboda, Jiří; Fischer, F. D.
2014-01-01
Roč. 22, č. 1 (2014), Art. No. 015013 ISSN 0965-0393 Institutional support: RVO:68081723 Keywords : grain boundary segregation * abnormal grain growth * theory * modelling * solute drag Subject RIV: BJ - Thermodynamics Impact factor: 2.167, year: 2014
The system Ta–V–Si: Thermodynamic modeling
Czech Academy of Sciences Publication Activity Database
Brož, P.; Khan, A.U.; Niu, H.; Chen, X.-Q.; Li, D.; Vřešťál, J.; Buršík, Jiří; Rogl, P.
2013-01-01
Roč. 199, MAR (2013), s. 171-180 ISSN 0022-4596 R&D Projects: GA ČR(CZ) GAP108/10/1908 Institutional support: RVO:68081723 Keywords : ternary alloy system * phase diagram * DFT calculations Subject RIV: BJ - Thermodynamics Impact factor: 2.200, year: 2013
Arrhenius And Absolute Reaction Rate Models for Thermodynamic ...
African Journals Online (AJOL)
Thermodynamic characterization of linamarase influenced by linamarin substrate purification, pH and temperature were investigated. In the study, recombinant Saccharomyces cerevisiae cells at the stationary phase of growth were recovered, homogenized and centrifuged to obtain crude extracts designated as GELIN0.
Maevskii, K. K.; Kinelovskii, S. A.
2017-12-01
The results of numerical modeling of thermodynamic parameters of oxides are presented by the example of periclase MgO and its mixtures under shock wave loading. The mixture of components experiencing the phase transition is investigated: quartz, SiO2, silicon nitride Si3N4, aluminum nitride AlN. The calculation results obtained by thermodynamic equilibrium component (TEC) models are compared with both the experimental data and the simulation results obtained by other authors.
Hidayat, Taufiq; Shishin, Denis; Decterov, Sergei A.; Hayes, Peter C.; Jak, Evgueni
2017-01-01
Uncertainty in the metal price and competition between producers mean that the daily operation of a smelter needs to target high recovery of valuable elements at low operating cost. Options for the improvement of the plant operation can be examined and decision making can be informed based on accurate information from laboratory experimentation coupled with predictions using advanced thermodynamic models. Integrated high-temperature experimental and thermodynamic modelling research on phase equilibria and thermodynamics of copper-containing systems have been undertaken at the Pyrometallurgy Innovation Centre (PYROSEARCH). The experimental phase equilibria studies involve high-temperature equilibration, rapid quenching and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA). The thermodynamic modelling deals with the development of accurate thermodynamic database built through critical evaluation of experimental data, selection of solution models, and optimization of models parameters. The database covers the Al-Ca-Cu-Fe-Mg-O-S-Si chemical system. The gas, slag, matte, liquid and solid metal phases, spinel solid solution as well as numerous solid oxide and sulphide phases are included. The database works within the FactSage software environment. Examples of phase equilibria data and thermodynamic models of selected systems, as well as possible implementation of the research outcomes to selected copper making processes are presented.
Thermodynamic properties of a quasi-harmonic model for ferroelectric transitions
International Nuclear Information System (INIS)
Mkam Tchouobiap, S E; Mashiyama, H
2011-01-01
Within a framework of a quasi-harmonic model for quantum particles in a local potential of the double Morse type and within the mean-field approximation for interactions between particles, we investigate the thermodynamic properties of ferroelectric materials. A quantum thermodynamic treatment gives analytic expressions for the internal energy, the entropy, the specific heat, and the static susceptibility. The calculated thermodynamic characteristics are studied as a function of temperature and energy barrier, where it is shown that at the proper choice of the theory parameters, particularly the energy barrier, the model system exhibits characteristic features of either second-order tricritical or first-order phase transitions. Our results indicate that the barrier energy seems to be an important criterion for the character of the structural phase transition. The influence of quantum fluctuations manifested on zero-point energy on the phase transition and thermodynamic properties is analyzed and discussed. This leads to several quantum effects, including the existence of a saturation regime at low temperatures, where the order parameter saturates giving thermodynamic saturation of the calculated thermodynamic quantities. It is found that both quantum effects and energy barrier magnitude have an important influence on the thermodynamic properties of the ferroelectric materials and on driving the phase transition at low temperatures. Also, the analytical parameters' effect on the transition temperature is discussed, which seems to give a general insight into the structural phase transition and its nature.
Thermodynamic model of a solid with RKKY interaction and magnetoelastic coupling
Balcerzak, T.; Szałowski, K.; Jaščur, M.
2018-04-01
Thermodynamic description of a model system with magnetoelastic coupling is presented. The elastic, vibrational, electronic and magnetic energy contributions are taken into account. The long-range RKKY interaction is considered together with the nearest-neighbour direct exchange. The generalized Gibbs potential and the set of equations of state are derived, from which all thermodynamic functions are self-consistently obtained. Thermodynamic properties are calculated numerically for FCC structure for arbitrary external pressure, magnetic field and temperature, and widely discussed. In particular, for some parameters of interaction potential and electron concentration corresponding to antiferromagnetic phase, the existence of negative thermal expansion coefficient is predicted.
Kartsev, V. N.; Polikhronidi, N. G.; Batov, D. V.; Shtykov, S. N.; Stepanov, G. V.
2010-02-01
An approach to the thermodynamics of microemulsions based on the use of the two-phase model was suggested. In this model, one phase is the dispersion medium, and the other, the sum of disperse phase nanodrops. Experimental estimation of the adequacy of this approach showed that the model can be used to quantitatively satisfactorily solve microemulsion thermodynamics problems. The degree of two-phase model inadequacy did not exceed 10%.
Cantera Integration with the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)
Lavelle, Thomas M.; Chapman, Jeffryes W.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei
2014-01-01
NASA Glenn Research Center (GRC) has recently developed a software package for modeling generic thermodynamic systems called the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a library of building blocks that can be assembled to represent any thermodynamic system in the Simulink (The MathWorks, Inc.) environment. These elements, along with a Newton Raphson solver (also provided as part of the T-MATS package), enable users to create models of a wide variety of systems. The current version of T-MATS (v1.0.1) uses tabular data for providing information about a specific mixture of air, water (humidity), and hydrocarbon fuel in calculations of thermodynamic properties. The capabilities of T-MATS can be expanded by integrating it with the Cantera thermodynamic package. Cantera is an object-oriented analysis package that calculates thermodynamic solutions for any mixture defined by the user. Integration of Cantera with T-MATS extends the range of systems that may be modeled using the toolbox. In addition, the library of elements released with Cantera were developed using MATLAB native M-files, allowing for quicker prototyping of elements. This paper discusses how the new Cantera-based elements are created and provides examples for using T-MATS integrated with Cantera.
Yang, Sam
The dissertation presents the mathematical formulation, experimental validation, and application of a volume element model (VEM) devised for modeling, simulation, and optimization of energy systems in their early design stages. The proposed model combines existing modeling techniques and experimental adjustment to formulate a reduced-order model, while retaining sufficient accuracy to serve as a practical system-level design analysis and optimization tool. In the VEM, the physical domain under consideration is discretized in space using lumped hexahedral elements (i.e., volume elements), and the governing equations for the variable of interest are applied to each element to quantify diverse types of flows that cross it. Subsequently, a system of algebraic and ordinary differential equations is solved with respect to time and scalar (e.g., temperature, relative humidity, etc.) fields are obtained in both spatial and temporal domains. The VEM is capable of capturing and predicting dynamic physical behaviors in the entire system domain (i.e., at system level), including mutual interactions among system constituents, as well as with their respective surroundings and cooling systems, if any. The VEM is also generalizable; that is, the model can be easily adapted to simulate and optimize diverse systems of different scales and complexity and attain numerical convergence with sufficient accuracy. Both the capability and generalizability of the VEM are demonstrated in the dissertation via thermal modeling and simulation of an Off-Grid Zero Emissions Building, an all-electric ship, and a vapor compression refrigeration (VCR) system. Furthermore, the potential of the VEM as an optimization tool is presented through the integrative thermodynamic optimization of a VCR system, whose results are used to evaluate the trade-offs between various objective functions, namely, coefficient of performance, second law efficiency, pull-down time, and refrigerated space temperature, in
Thermodynamics of protein folding using a modified Wako-Saitô-Muñoz-Eaton model.
Tsai, Min-Yeh; Yuan, Jian-Min; Teranishi, Yoshiaki; Lin, Sheng Hsien
2012-09-01
Herein, we propose a modified version of the Wako-Saitô-Muñoz-Eaton (WSME) model. The proposed model introduces an empirical temperature parameter for the hypothetical structural units (i.e., foldons) in proteins to include site-dependent thermodynamic behavior. The thermodynamics for both our proposed model and the original WSME model were investigated. For a system with beta-hairpin topology, a mathematical treatment (contact-pair treatment) to facilitate the calculation of its partition function was developed. The results show that the proposed model provides better insight into the site-dependent thermodynamic behavior of the system, compared with the original WSME model. From this site-dependent point of view, the relationship between probe-dependent experimental results and model's thermodynamic predictions can be explained. The model allows for suggesting a general principle to identify foldon behavior. We also find that the backbone hydrogen bonds may play a role of structural constraints in modulating the cooperative system. Thus, our study may contribute to the understanding of the fundamental principles for the thermodynamics of protein folding.
Thermodynamic modelling of acid gas removal from natural gas using the Extended UNIQUAC model
DEFF Research Database (Denmark)
Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj
2017-01-01
Thermodynamics of natural gas sweetening process needs to be known for proper design of natural gas treating plants. Absorption with aqueous N-Methyldiethanolamine is currently the most commonly used process for removal of acid gas (CO2 and H2S) impurities from natural gas. Model parameters...... for the Extended UNIQUAC model have already been determined by the same authors to calculate single acid gas solubility in aqueous MDEA. In this study, the model is further extended to estimate solubility of CO2 and H2S and their mixture in aqueous MDEA at high pressures with methane as a makeup gas....
Energy Technology Data Exchange (ETDEWEB)
Xiao Yamping; Holappa, L. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Metallurgy
1996-12-31
This article summaries the research work on thermodynamics of chromium slags and kinetic modelling of chromite reduction. The thermodynamic properties of FeCr slag systems were calculated with the regular solution model. The effects of CaO/MgO ratio, Al{sub 2}0{sub 3} amount as well as the slag basicity on the activities of chromium oxides and the oxidation state of chromium were examined. The calculated results were compared to the experimental data in the literature. In the kinetic modelling of the chromite reduction, the reduction possibilities and tendencies of the chromite constitutes with CO were analysed based on the thermodynamic calculation. Two reaction models, a structural grain model and a multi-layers reaction model, were constructed and applied to simulate the chromite pellet reduction and chromite lumpy ore reduction, respectively. The calculated reduction rates were compared with the experimental measurements and the reaction mechanisms were discussed. (orig.) SULA 2 Research Programme; 4 refs.
Development of a thermodynamic data base for selected heavy metals
International Nuclear Information System (INIS)
Hageman, Sven; Scharge, Tina; Willms, Thomas
2015-07-01
The report on the development of a thermodynamic data base for selected heavy metals covers the description of experimental methods, the thermodynamic model for chromate, the thermodynamic model for dichromate, the thermodynamic model for manganese (II), the thermodynamic model for cobalt, the thermodynamic model for nickel, the thermodynamic model for copper (I), the thermodynamic model for copper(II), the thermodynamic model for mercury (0) and mercury (I), the thermodynamic model for mercury (III), the thermodynamic model for arsenate.
Solution chemistry of Mo(III) and Mo(IV): Thermodynamic foundation for modeling localized corrosion
International Nuclear Information System (INIS)
Wang Peiming; Wilson, Leslie L.; Wesolowski, David J.; Rosenqvist, Joergen; Anderko, Andrzej
2010-01-01
To investigate the behavior of molybdenum dissolution products in systems that approximate localized corrosion environments, solubility of Mo(III) in equilibrium with solid MoO 2 has been determined at 80 deg. C as a function of solution acidity, chloride concentration and partial pressure of hydrogen. The measurements indicate a strong increase in solubility with acidity and chloride concentration and a weak effect of hydrogen partial pressure. The obtained results have been combined with literature data for systems containing Mo(III), Mo(IV), and Mo(VI) in solutions to develop a comprehensive thermodynamic model of aqueous molybdenum chemistry. The model is based on a previously developed framework for simulating the properties of electrolyte systems ranging from infinite dilution to solid saturation or fused salt limit. To reproduce the measurements, the model assumes the presence of a chloride complex of Mo(III) (i.e., MoCl 2+ ) and hydrolyzed species (MoOH 2+ , Mo(OH) 2 + , and Mo(OH) 3 0 ) in addition to the Mo 3+ ion. The model generally reproduces the experimental data within experimental scattering and provides a tool for predicting the phase behavior and speciation in complex, concentrated aqueous solutions. Thus, it provides a foundation for simulating the behavior of molybdenum species in localized corrosion environments.
Alien wavelength modeling tool and field trial
DEFF Research Database (Denmark)
Sambo, N.; Sgambelluri, A.; Secondini, M.
2015-01-01
A modeling tool is presented for pre-FEC BER estimation of PM-QPSK alien wavelength signals. A field trial is demonstrated and used as validation of the tool's correctness. A very close correspondence between the performance of the field trial and the one predicted by the modeling tool has been...
Analysis of the Glass-Forming Ability of Fe-Er Alloys, Based on Thermodynamic Modeling
Arutyunyan, N. A.; Zaitsev, A. I.; Dunaev, S. F.; Kalmykov, K. B.; El'nyakov, D. D.; Shaposhnikov, N. G.
2018-05-01
The Fe-Er phase diagram and thermodynamic properties of all its phases are assessed by means of self-consistent analysis. To refine the data on phase equilibria in the Fe-Er system, an investigation is performed in the 10-40 at % range of Er concentrations. The temperature-concentration dependences of the thermodynamic properties of a melt are presented using the model of ideal associated solutions. Thermodynamic parameters of each phase are obtained, and the calculated results are in agreement with available experimental data. The correlation between the thermodynamic properties of liquid Fe-Er alloys and their tendency toward amorphization are studied. It is shown that compositions of amorphous alloys prepared by melt quenching coincide with the ranges of concentration with the predominance of Fe3Er and FeEr2 associative groups that have large negative entropies of formation.
Thermodynamic and Process Modelling of Gas Hydrate Systems in CO2 Capture Processes
DEFF Research Database (Denmark)
Herslund, Peter Jørgensen
in this work compares well with other data available in the literature for similar systems. It is shown experimentally that the addition of tetrahydrofuran to the ternary system of water-cyclopentane-carbon dioxide provides an enhanced thermodynamic promotion of the gas hydrate phase. Hydrate equilibrium...... and tetrahydrofuran as the two most efficient pressure reducing additives in classical hydrate forming systems. The thermodynamic promoting effects reported in the literature for the two classical sII hydrate formers, tetrahydrofuran and cyclopentane are experimentally confirmed in the present work. Data presented...... pressures are reduced by approximately 20 percent compared to the cyclopentane promoted system. The mixed promoter system thereby represents a new state-ofthe-art within thermodynamic promotion of gas hydrates in the framework of the classical hydrate structures. A thermodynamic model based on the Cubic...
Thermodynamic Model and Experimental Study of Oil-free Scroll Compressor
Peng, Bin; Zhao, Shengxian; Li, Yaohong
2017-10-01
In order to study the performance characteristics of oil-free scroll compressor, this paper is based on the basic equation of circle involute profile, and uses the differential geometry theory to calculate the variation law of pressure with volume. Based on the basic law of thermodynamics, the thermodynamic model of the oil-free scroll compressor is established by considering the heat transfer model and the gas leakage model, considering the mass, energy conservation equation and gas state equation. The change of the mass flow rate of the gas in each chamber is obtained by solving the established model by using the improved Euler method. The experiment results show that with the increase of frequency, the temperature, the displacement and the power show a clear upward trend. The thermodynamic model has some guidance and reference for the development and performance analysis of oil-free scroll compressors.
Czech Academy of Sciences Publication Activity Database
Svoboda, Jiří; Turek, Ilja; Fischer, F. D.
2005-01-01
Roč. 85, č. 31 (2005), s. 3699-3707 ISSN 1460-6992 R&D Projects: GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : Modelling Subject RIV: BM - Solid Matter Physics ; Magnetism
International Nuclear Information System (INIS)
Moog, Helge C.; Regenspurg, Simona; Voigt, Wolfgang
2015-02-01
The concept for geothermal energy application for electricity generation can be differentiated into three compartments: In the geologic compartment cooled fluid is pressed into a porous or fractured rock formation, in the borehole compartment a hot fluid is pumped to the surface and back into the geothermal reservoir, in the aboveground facility the energy is extracted from the geothermal fluid by heat exchangers. Pressure and temperature changes influence the thermodynamic equilibrium of a system. The modeling of a geothermal system has therefore to consider besides the mass transport the heat transport and consequently changing solution compositions and the pressure/temperature effected chemical equilibrium. The GEODAT project is aimed to simulate the reactive mass transport in a geothermal reservoir in the North German basin (Gross Schoenebeck). The project was performed by the cooperation of three partners: Geoforschungsinstitut Potsdam, Bergakademie Freiberg and GRS.
Energy Technology Data Exchange (ETDEWEB)
Lo, Ch. K.; Lim, Y. S.; Tan, S. G.; Rahman, F. A. [Faculty of Engineering and Science, University Tunku Abdul Rahman, Jalan Genting Klang, 53300, Kuala Lumpur (Malaysia)
2010-12-15
A Luminescent Solar Concentrator (LSC) is a transparent plate containing luminescent material with photovoltaic (PV) cells attached to its edges. Sunlight entering the plate is absorbed by the luminescent material, which in turn emits light. The emitted light propagates through the plate and arrives at the PV cells through total internal reflection. The ratio of the area of the relatively cheap polymer plate to that of the expensive PV cells is increased, and the cost per unit of solar electricity can be reduced by 75%. To improve the emission performance of LSCs, simulation modeling of LSCs becomes essential. Ray-tracing modeling is a popular approach for simulating LSCs due to its great ability of modeling various LSC structures under direct and diffuse sunlight. However, this approach requires substantial amount of measurement input data. Also, the simulation time is enormous because it is a forward-ray tracing method that traces all the rays propagating from the light source to the concentrator. On the other hand, the thermodynamic approach requires substantially less input parameters and simulation time, but it can only be used to model simple LSC designs with direct sunlight. Therefore, a new hybrid model was developed to perform various simulation studies effectively without facing the issues arisen from the existing ray-tracing and thermodynamic models. The simulation results show that at least 60% of the total output irradiance of a LSC is contributed by the light trapped and channeled by the LSC. The novelty of this hybrid model is the concept of integrating the thermodynamic model with a well-developed Radiance ray-tracing model, hence making this model as a fast, powerful and cost-effective tool for the design of LSCs. (authors)
Directory of Open Access Journals (Sweden)
Chin Kim Lo
2010-11-01
Full Text Available A Luminescent Solar Concentrator (LSC is a transparent plate containing luminescent material with photovoltaic (PV cells attached to its edges. Sunlight entering the plate is absorbed by the luminescent material, which in turn emits light. The emitted light propagates through the plate and arrives at the PV cells through total internal reflection. The ratio of the area of the relatively cheap polymer plate to that of the expensive PV cells is increased, and the cost per unit of solar electricity can be reduced by 75%. To improve the emission performance of LSCs, simulation modeling of LSCs becomes essential. Ray-tracing modeling is a popular approach for simulating LSCs due to its great ability of modeling various LSC structures under direct and diffuse sunlight. However, this approach requires substantial amount of measurement input data. Also, the simulation time is enormous because it is a forward-ray tracing method that traces all the rays propagating from the light source to the concentrator. On the other hand, the thermodynamic approach requires substantially less input parameters and simulation time, but it can only be used to model simple LSC designs with direct sunlight. Therefore, a new hybrid model was developed to perform various simulation studies effectively without facing the issues arisen from the existing ray-tracing and thermodynamic models. The simulation results show that at least 60% of the total output irradiance of a LSC is contributed by the light trapped and channeled by the LSC. The novelty of this hybrid model is the concept of integrating the thermodynamic model with a well-developed Radiance ray-tracing model, hence making this model as a fast, powerful and cost-effective tool for the design of LSCs.
Theoretical models for fluid thermodynamics based on the quasi-Gaussian entropy theory
Amadei, Andrea
1998-01-01
Summary The theoretical modeling of fluid thermodynamics is one of the most challenging fields in physical chemistry. In fact the fluid behavior, except at very low density conditions, is still extremely difficult to be modeled from a statistical mechanical point of view, as for any realistic model
A thermodynamic model of the Z-phase Cr(V, Nb)N
DEFF Research Database (Denmark)
Danielsen, Hilmar Kjartansson; Hald, John
2007-01-01
. A thermodynamic model of the Z-phase has been developed based on the regular solution model. The model predicts Z-phase to be stable and to fully replace the MX particles in most of the new 9%–12% Cr steels, which is in good agreement with experimental observations. The rate of precipitation of Z...
A spreadsheet-coupled SOLGAS: A computerized thermodynamic equilibrium calculation tool. Revision 1
Energy Technology Data Exchange (ETDEWEB)
Trowbridge, L.D.; Leitnaker, J.M. [Oak Ridge K-25 Site, TN (United States). Technical Analysis and Operations Div.
1995-07-01
SOLGAS, an early computer program for calculating equilibrium in a chemical system, has been made more user-friendly, and several ``bells and whistles`` have been added. The necessity to include elemental species has been eliminated. The input of large numbers of starting conditions has been automated. A revised spreadsheet-based format for entering data, including non-ideal binary and ternary mixtures, simplifies and reduces chances for error. Calculational errors by SOLGAS are flagged, and several programming errors are corrected. Auxiliary programs are available to assemble and partially automate plotting of large amounts of data. Thermodynamic input data can be changed on line. The program can be operated with or without a co-processor. Copies of the program, suitable for the IBM-PC or compatibles with at least 384 bytes of low RAM, are available from the authors. This user manual contains appendices with examples of the use of SOLGAS. These range from elementary examples, such as, the relationships among water, ice, and water vapor, to more complex systems: phase diagram calculation of UF{sub 4} and UF{sub 6} system; burning UF{sub 4} in fluorine; thermodynamic calculation of the Cl-F-O-H system; equilibria calculations in the CCl{sub 4}--CH{sub 3}OH system; and limitations applicable to aqueous solutions. An appendix also contains the source code.
A numerical model on thermodynamic analysis of free piston Stirling engines
Mou, Jian; Hong, Guotong
2017-02-01
In this paper, a new numerical thermodynamic model which bases on the energy conservation law has been used to analyze the free piston Stirling engine. In the model all data was taken from a real free piston Stirling engine which has been built in our laboratory. The energy conservation equations have been applied to expansion space and compression space of the engine. The equation includes internal energy, input power, output power, enthalpy and the heat losses. The heat losses include regenerative heat conduction loss, shuttle heat loss, seal leakage loss and the cavity wall heat conduction loss. The numerical results show that the temperature of expansion space and the temperature of compression space vary with the time. The higher regeneration effectiveness, the higher efficiency and bigger output work. It is also found that under different initial pressures, the heat source temperature, phase angle and engine work frequency pose different effects on the engine’s efficiency and power. As a result, the model is expected to be a useful tool for simulation, design and optimization of Stirling engines.
Technical Work Plan for: Thermodynamic Databases for Chemical Modeling
International Nuclear Information System (INIS)
C.F. Jovecolon
2006-01-01
The objective of the work scope covered by this Technical Work Plan (TWP) is to correct and improve the Yucca Mountain Project (YMP) thermodynamic databases, to update their documentation, and to ensure reasonable consistency among them. In addition, the work scope will continue to generate database revisions, which are organized and named so as to be transparent to internal and external users and reviewers. Regarding consistency among databases, it is noted that aqueous speciation and mineral solubility data for a given system may differ according to how solubility was determined, and the method used for subsequent retrieval of thermodynamic parameter values from measured data. Of particular concern are the details of the determination of ''infinite dilution'' constants, which involve the use of specific methods for activity coefficient corrections. That is, equilibrium constants developed for a given system for one set of conditions may not be consistent with constants developed for other conditions, depending on the species considered in the chemical reactions and the methods used in the reported studies. Hence, there will be some differences (for example in log K values) between the Pitzer and ''B-dot'' database parameters for the same reactions or species
Technical Work Plan for: Thermodynamic Database for Chemical Modeling
Energy Technology Data Exchange (ETDEWEB)
C.F. Jovecolon
2006-09-07
The objective of the work scope covered by this Technical Work Plan (TWP) is to correct and improve the Yucca Mountain Project (YMP) thermodynamic databases, to update their documentation, and to ensure reasonable consistency among them. In addition, the work scope will continue to generate database revisions, which are organized and named so as to be transparent to internal and external users and reviewers. Regarding consistency among databases, it is noted that aqueous speciation and mineral solubility data for a given system may differ according to how solubility was determined, and the method used for subsequent retrieval of thermodynamic parameter values from measured data. Of particular concern are the details of the determination of ''infinite dilution'' constants, which involve the use of specific methods for activity coefficient corrections. That is, equilibrium constants developed for a given system for one set of conditions may not be consistent with constants developed for other conditions, depending on the species considered in the chemical reactions and the methods used in the reported studies. Hence, there will be some differences (for example in log K values) between the Pitzer and ''B-dot'' database parameters for the same reactions or species.
Steepest entropy ascent quantum thermodynamic model of electron and phonon transport
Li, Guanchen; von Spakovsky, Michael R.; Hin, Celine
2018-01-01
An advanced nonequilibrium thermodynamic model for electron and phonon transport is formulated based on the steepest-entropy-ascent quantum thermodynamics framework. This framework, based on the principle of steepest entropy ascent (or the equivalent maximum entropy production principle), inherently satisfies the laws of thermodynamics and mechanics and is applicable at all temporal and spatial scales even in the far-from-equilibrium realm. Specifically, the model is proven to recover the Boltzmann transport equations in the near-equilibrium limit and the two-temperature model of electron-phonon coupling when no dispersion is assumed. The heat and mass transport at a temperature discontinuity across a homogeneous interface where the dispersion and coupling of electron and phonon transport are both considered are then modeled. Local nonequilibrium system evolution and nonquasiequilibrium interactions are predicted and the results discussed.
Hamilton, Joshua J.; Dwivedi, Vivek; Reed, Jennifer L.
2013-01-01
Constraint-based methods provide powerful computational techniques to allow understanding and prediction of cellular behavior. These methods rely on physiochemical constraints to eliminate infeasible behaviors from the space of available behaviors. One such constraint is thermodynamic feasibility, the requirement that intracellular flux distributions obey the laws of thermodynamics. The past decade has seen several constraint-based methods that interpret this constraint in different ways, including those that are limited to small networks, rely on predefined reaction directions, and/or neglect the relationship between reaction free energies and metabolite concentrations. In this work, we utilize one such approach, thermodynamics-based metabolic flux analysis (TMFA), to make genome-scale, quantitative predictions about metabolite concentrations and reaction free energies in the absence of prior knowledge of reaction directions, while accounting for uncertainties in thermodynamic estimates. We applied TMFA to a genome-scale network reconstruction of Escherichia coli and examined the effect of thermodynamic constraints on the flux space. We also assessed the predictive performance of TMFA against gene essentiality and quantitative metabolomics data, under both aerobic and anaerobic, and optimal and suboptimal growth conditions. Based on these results, we propose that TMFA is a useful tool for validating phenotypes and generating hypotheses, and that additional types of data and constraints can improve predictions of metabolite concentrations. PMID:23870272
Modeling of Energy Management Systems for Commercial Parks with Thermodynamic Equipment
Shanshan, Shi; Yu, Zhang; Liuyang, Fan; Tian, Luo
2017-05-01
Commercial park energy management systems (CPEMS) can reasonably plan appliances’ schedule of commercial tenants (CT) and lower their electricity purchasing cost. However, in the existing models, thermodynamic equipment like air conditioners and water heaters are not precise enough, failing to reflect the actual operating characteristics of the equipment. This paper presents an energy management system model including thermodynamic equipment. By coordinating the electricity consumption schedule of multiple CTs, CPEMS can reduce CTs’ electricity purchase costs. In the demonstration example, electricity purchase costs of CTs are reduced and operators of CPEMS gain profit, proving the feasibility of the model.
Thermodynamic Modeling of Organic-Inorganic Aerosols with the Group-Contribution Model AIOMFAC
Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.
2009-04-01
Liquid aerosol particles are - from a physicochemical viewpoint - mixtures of inorganic salts, acids, water and a large variety of organic compounds (Rogge et al., 1993; Zhang et al., 2007). Molecular interactions between these aerosol components lead to deviations from ideal thermodynamic behavior. Strong non-ideality between organics and dissolved ions may influence the aerosol phases at equilibrium by means of liquid-liquid phase separations into a mainly polar (aqueous) and a less polar (organic) phase. A number of activity models exists to successfully describe the thermodynamic equilibrium of aqueous electrolyte solutions. However, the large number of different, often multi-functional, organic compounds in mixed organic-inorganic particles is a challenging problem for the development of thermodynamic models. The group-contribution concept as introduced in the UNIFAC model by Fredenslund et al. (1975), is a practical method to handle this difficulty and to add a certain predictability for unknown organic substances. We present the group-contribution model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients), which explicitly accounts for molecular interactions between solution constituents, both organic and inorganic, to calculate activities, chemical potentials and the total Gibbs energy of mixed systems (Zuend et al., 2008). This model enables the computation of vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria within one framework. Focusing on atmospheric applications we considered eight different cations, five anions and a wide range of alcohols/polyols as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are very well represented up to high ionic strength. We show that the semi-empirical middle-range parametrization of direct organic-inorganic interactions in alcohol-water-salt solutions enables accurate computations of vapor-liquid and liquid
Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys
Directory of Open Access Journals (Sweden)
S. Abdessameud
2014-01-01
Full Text Available Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.
Directory of Open Access Journals (Sweden)
Chellaboina Vijaysekhar
2005-01-01
Full Text Available We develop thermodynamic models for discrete-time large-scale dynamical systems. Specifically, using compartmental dynamical system theory, we develop energy flow models possessing energy conservation, energy equipartition, temperature equipartition, and entropy nonconservation principles for discrete-time, large-scale dynamical systems. Furthermore, we introduce a new and dual notion to entropy; namely, ectropy, as a measure of the tendency of a dynamical system to do useful work and grow more organized, and show that conservation of energy in an isolated thermodynamic system necessarily leads to nonconservation of ectropy and entropy. In addition, using the system ectropy as a Lyapunov function candidate, we show that our discrete-time, large-scale thermodynamic energy flow model has convergent trajectories to Lyapunov stable equilibria determined by the system initial subsystem energies.
Energy Technology Data Exchange (ETDEWEB)
Meyer, B.; Starke, A. [TU Bergakademie Freiberg (Germany)
1998-12-31
As a promising tool for the further development of thermochemical fuel utilisation processes thermodynamic modelling has become a focal area of research and development at the Institute for Energy Process Engineering and Chemical Engineering. Its application to coal power plant technology is the furthest advanced. The present paper gives concrete examples of its use in this area: high-temperature chlorine corrosion, heavy metal volatility, and alkali bonding in slags. For the first time it has been possible to develop and successfully apply a closed real-phase model of hard coal slags. The presented methodology opens up new possibilities for theoretically well-founded process development, optimisation, and control. (orig.) [Deutsch] Die thermodynamische Modellierung ist ein aussichtsreiches Werkzeug fuer die Weiterentwicklung thermisch-chemischer Prozesse der Brennstoffverwertung sowie ein Forschungs- und Entwicklungsschwerpunkt des Institutes fuer Energieverfahrenstechnik und Chemieingenieurwesen. Die Anwendung fuer Kohlekraftwerkstechnik ist am weitesten fortgeschritten. Dies wird anhand von konkreten Beispielen - die Hochtemperatur-Chlor-Korrosion, die Schwermetall-Fluechtigkeit und die Alkalieinbindung in Schlacken - gezeigt. Erstmals wurde ein geschlossenes Realphasenmodell von Steinkohlenschlacken erstellt und erfolgreich angewendet. Die vorgestellte Methodik eroeffnet neue Moeglichkeiten fuer eine theoretisch fundierte Prozessentwicklung, -optimierung und -steuerung. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Wolery, Thomas J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tayne, Andrew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jove-Colon, Carlos F. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)
2011-07-29
Thermodynamic data are essential for understanding and evaluating geochemical processes, as by speciation-solubility calculations, reaction -path modeling, or reactive transport simulation. These data are required to evaluate both equilibrium states and the kinetic approach to such states (via the affinity term in rate laws). The development of thermodynamic databases for these purposes has a long history in geochemistry (e.g., Garrels and Christ, 1965; Helgeson et al., 1969; Helgeson et al., 1978, Johnson et al., 1992; Robie and Hemingway, 1995), paralleled by related and applicable work in the larger scientific community (e.g., Wagman et al., 1982, 1989; Cox et al., 1989; Barin and Platzki, 1995; Binneweis and Milke, 1999). The Yucca Mountain Project developed two qualified thermodynamic databases for to model geochemical processes, including ones involving repository components such as spent fuel. The first of the two (BSC, 2007a) was for systems containing dilute aqueous solutions only, the other (BSC, 2007b) for systems involving concentrated aqueous solutions and incorporating a model for such based on Pitzer’s (1991) equations . A 25°C-only database with similarities to the latter was also developed for WIPP (cf. Xiong, 2005). The YMP dilute systems database is widely used in the geochemistry community for a variety of applications involving rock/water interactions. The purpose of the present task is to improve these databases for work on the Used Fuel Disposition Project and maintain some semblance of order that will support qualification in support of the development of future underground high level nuclear waste disposal.
International Nuclear Information System (INIS)
Sutton, S.B.; Stein, W.; Reitter, T.A.; Hindmarsh, A.C.
1983-01-01
A numerical model for calculating the thermodynamic behavior of the MFTF-B cryogenic cooling system is described. Nine component types are discussed with governing equations given. The algorithm for solving the coupled set of algebraic and ordinary differential equations is described. The model and its application to the MFTF-B cryogenic cooling system has not been possible due to lack of funding
The Matrix model, a driven state variables approach to non-equilibrium thermodynamics
Jongschaap, R.J.J.
2001-01-01
One of the new approaches in non-equilibrium thermodynamics is the so-called matrix model of Jongschaap. In this paper some features of this model are discussed. We indicate the differences with the more common approach based upon internal variables and the more sophisticated Hamiltonian and GENERIC
Thermodynamic modelling of phase equilibria in Al–Ga–P–As system
Indian Academy of Sciences (India)
A generalized thermodynamic expression of the liquid Al–Ga–P–As alloys is used in conjunction with the solid solution model in determining the solid–liquid equilibria at 1173 K and 1273 K. The liquid solution model contains thirtyseven parameters. Twentyfour of them pertain to those of the six constituent binaries, twelve ...
Directory of Open Access Journals (Sweden)
Mohamad Javad Kamali
2015-01-01
Full Text Available Thermodynamic modeling of surface tension of different electrolyte systems in presence of gas phase is studied. Using the solid-liquid equilibrium, Langmuir gas-solid adsorption, and ENRTL activity coefficient model, the surface tension of electrolyte solutions is calculated. The new model has two adjustable parameters which could be determined by fitting the experimental surface tension of binary aqueous electrolyte solution in single temperature. Then the values of surface tension for other temperatures in binary and ternary system of aqueous electrolyte solution are predicted. The average absolute deviations for calculation of surface tension of binary and mixed electrolyte systems by new model are 1.98 and 1.70%, respectively.
Reversible thermodynamic cycle analysis for capacitive deionization with modified Donnan model.
Wang, Li; Biesheuvel, P M; Lin, Shihong
2018-02-15
It is a widely accepted principle that a thermodynamically reversible desalination process should consume the Gibbs free energy of separation. This principle has been shown in reverse osmosis and has important practical implications in reducing its energy consumption. Capacitive deionization (CDI) with carbon electrodes, a desalination process based on electrical double layer (EDL) formation, should also follow such a principle when it operates in a thermodynamically reversible way. Inspired by a previous thermodynamic analysis on a three-stage reversible CDI process using the Gouy-Chapman-Stern model, we conducted a thermodynamic analysis of a four-stage reversible CDI cycle using the modified Donnan model. This analysis better reflects the cyclic nature of practical CDI operations and account for the significant EDL overlap in nanosized micropores of realistic CDI electrodes. Our analysis of CDI cycles with different separations and final discharge voltages shows that the electrical work to complete a four-stage cycles is numerically exactly identical to the Gibbs free energy of separation, as long as the cycle is operated in a thermodynamically reversible manner. Copyright © 2017 Elsevier Inc. All rights reserved.
Thermodynamics for scientists and engineers
International Nuclear Information System (INIS)
Lim, Gyeong Hui
2011-02-01
This book deals with thermodynamics for scientists and engineers. It consists of 11 chapters, which are concept and background of thermodynamics, the first law of thermodynamics, the second law of thermodynamics and entropy, mathematics related thermodynamics, properties of thermodynamics on pure material, equilibrium, stability of thermodynamics, the basic of compound, phase equilibrium of compound, excess gibbs energy model of compound and activity coefficient model and chemical equilibrium. It has four appendixes on properties of pure materials and thermal mass.
Directory of Open Access Journals (Sweden)
Liliana Giraldo
2008-10-01
Full Text Available The interaction of guest molecules ranging from pentan-1-ol to octan-1-ol with ÃŽÂ±-cyclodextrin (ÃŽÂ±-CD in water of has been studied calorimetrically at 283.15, 288.15, 293.15, 298.15 and 308.15 K with an isoperibolic titration calorimeter designed in our laboratory. The calorimetric method employed allows the determination of the thermodynamic parameters characterizing the binding process, ÃŽÂ”GÃ‚Â°m, ÃŽÂ”HÃ‚Â°m, ÃŽÂ”SÃ‚Â°mand ÃŽÂ”CpÃ‚Â°, namely free energy, enthalpy, and calorific capacity. These results show that in the temperature range investigated, the entropy change increased with chain length. This is in line with what is expected for a hydrophobic dehydration process. However, that effect is not expected to lead to the more pronounced negative CH2-increment observed for nc > 5 or 6. As for many other ligand binding processes, we can observe a significant enthalpy - entropy compensation for this system, both with respect to temperature and structure.
Energy Technology Data Exchange (ETDEWEB)
Moreno-Pirajan, J. C. [Universidad de los Andes, Bogota, Grupo de investigacion en solidos porosos y calorimetria, Departamento de Quimica, Facultad de Ciencias / Carrera 1 No.18 A10, Bogota (Colombia); Giraldo, L. [Universidad Nacional de Colombia, Facultad de Ciencias, Departamento de Quimica / Ciudad Universitaria, Bogota (Colombia)
2008-07-01
The interaction of guest molecules ranging from pentan-1-ol to octan-1-ol with {alpha}-cyclodextrin ({alpha}-CD) in water of has been studied calorimetrically at 283.15, 288.15, 293.15, 298.15 and 308.15 K with an isoperibolic titration calorimeter designed in our laboratory. The calorimetric method employed allows the determination of the thermodynamic parameters characterizing the binding process, {delta}G {sup o}{sub m}, {delta}H {sup o}{sub m}, {delta}S {sup o}{sub m} and {delta}Cp {sup o}, namely free energy, enthalpy, and calorific capacity. These results show that in the temperature range investigated, the entropy change increased with chain length. This is in line with what is expected for a hydrophobic dehydration process. However, that effect is not expected to lead to the more pronounced negative CH{sub 2}-increment observed for n{sub c} > 5 or 6. As for many other ligand binding processes, we can observe a significant enthalpy - entropy compensation for this system, both with respect to temperature and structure. (author)
Requirements for clinical information modelling tools.
Moreno-Conde, Alberto; Jódar-Sánchez, Francisco; Kalra, Dipak
2015-07-01
This study proposes consensus requirements for clinical information modelling tools that can support modelling tasks in medium/large scale institutions. Rather than identify which functionalities are currently available in existing tools, the study has focused on functionalities that should be covered in order to provide guidance about how to evolve the existing tools. After identifying a set of 56 requirements for clinical information modelling tools based on a literature review and interviews with experts, a classical Delphi study methodology was applied to conduct a two round survey in order to classify them as essential or recommended. Essential requirements are those that must be met by any tool that claims to be suitable for clinical information modelling, and if we one day have a certified tools list, any tool that does not meet essential criteria would be excluded. Recommended requirements are those more advanced requirements that may be met by tools offering a superior product or only needed in certain modelling situations. According to the answers provided by 57 experts from 14 different countries, we found a high level of agreement to enable the study to identify 20 essential and 21 recommended requirements for these tools. It is expected that this list of identified requirements will guide developers on the inclusion of new basic and advanced functionalities that have strong support by end users. This list could also guide regulators in order to identify requirements that could be demanded of tools adopted within their institutions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Comparison of two different modelling tools
DEFF Research Database (Denmark)
Brix, Wiebke; Elmegaard, Brian
2009-01-01
In this paper a test case is solved using two different modelling tools, Engineering Equation Solver (EES) and WinDali, in order to compare the tools. The system of equations solved, is a static model of an evaporator used for refrigeration. The evaporator consists of two parallel channels, and i...
DEFF Research Database (Denmark)
Faramarzi, Leila; Kontogeorgis, Georgios; Thomsen, Kaj
2009-01-01
The extended UNIQUAC model [K. Thomsen, R Rasmussen, Chem. Eng. Sci. 54 (1999) 1787-1802] was applied to the thermodynamic representation of carbon dioxide absorption in aqueous monoethanolamine (MEA), methyldiethanolamine (MDEA) and varied strength mixtures of the two alkanolamines (MEA-MDEA). F......The extended UNIQUAC model [K. Thomsen, R Rasmussen, Chem. Eng. Sci. 54 (1999) 1787-1802] was applied to the thermodynamic representation of carbon dioxide absorption in aqueous monoethanolamine (MEA), methyldiethanolamine (MDEA) and varied strength mixtures of the two alkanolamines (MEA...... alkanolamine systems (MEA-water and MDEA-water). The two just mentioned types of data cover the full concentration range of alkanolamines from extremely dilute to almost pure. The experimental freezing point depression data down to the temperature of -20 degrees C are used. Experimental excess enthalpy (H......-E) data of the binary MEA-water and MDEA-water systems at 25, 40, 65 and 69 degrees C are used as well. In order to enhance the calculation of the infinite dilution activity coefficients of MEA and MDEA, the pure alkanolamines vapor pressure data in a relevant temperature range (up to almost 230 degrees C...
International Nuclear Information System (INIS)
Barjaneh, Afshin; Sayyaadi, Hoseyn
2015-01-01
Highlights: • A new closed-form thermal model was developed for SI engines. • Various irreversibilities of real engines were integrated into the model. • The accuracy of the model was examined on two real SI engines. • The superiority of the model to previous closed-form models was shown. • Accuracy and losses were studied over the operating range of engines. - Abstract: A closed form model based on finite speed thermodynamics, FST, modified to consider various losses was developed on Otto cycle. In this regard, the governing equations of the finite speed thermodynamics were developed for expansion/compression processes while heat absorption/rejection of the Otto cycle was determined based on finite time thermodynamics, FTT. In addition, other irreversibility including power loss caused by heat transfer through the cylinder walls and irreversibility due to throttling process was integrated into the model. The developed model was verified by implementing on two different spark ignition internal combustion engines and the results of modeling were compared with experimental results as well as FTT model. It was found that the developed model was not only very simple in use like a closed form thermodynamic model, but also it models a real spark ignition engine with reasonable accuracy. The error in predicting the output power at rated operating range of the engine was 39%, while in the case of the FTT model, this figure was 167.5%. This comparison for predicting thermal efficiency was +7% error (as difference) for the developed model compared to +39.4% error of FTT model.
Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Jonathan S.
2014-01-01
The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3% of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.
Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Johathan S.
2014-01-01
The Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3 of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.
Energy Technology Data Exchange (ETDEWEB)
Jack Istok; Melora Park; James McKinley; Chongxuan Liu; Lee Krumholz; Anne Spain; Aaron Peacock; Brett Baldwin
2007-04-19
The overall goal of this project is to develop and test a thermodynamic network model for predicting the effects of substrate additions and environmental perturbations on microbial growth, community composition and system geochemistry. The hypothesis is that a thermodynamic analysis of the energy-yielding growth reactions performed by defined groups of microorganisms can be used to make quantitative and testable predictions of the change in microbial community composition that will occur when a substrate is added to the subsurface or when environmental conditions change.
Huang, M.; Rivera-Diaz-del-Castillo, P.E.J.; Bouaziz, O.; Van der Zwaag, S.
2009-01-01
Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that
Network Thermodynamic Curation of Human and Yeast Genome-Scale Metabolic Models
Martínez, Verónica S.; Quek, Lake-Ee; Nielsen, Lars K.
2014-01-01
Genome-scale models are used for an ever-widening range of applications. Although there has been much focus on specifying the stoichiometric matrix, the predictive power of genome-scale models equally depends on reaction directions. Two-thirds of reactions in the two eukaryotic reconstructions Homo sapiens Recon 1 and Yeast 5 are specified as irreversible. However, these specifications are mainly based on biochemical textbooks or on their similarity to other organisms and are rarely underpinned by detailed thermodynamic analysis. In this study, a to our knowledge new workflow combining network-embedded thermodynamic and flux variability analysis was used to evaluate existing irreversibility constraints in Recon 1 and Yeast 5 and to identify new ones. A total of 27 and 16 new irreversible reactions were identified in Recon 1 and Yeast 5, respectively, whereas only four reactions were found with directions incorrectly specified against thermodynamics (three in Yeast 5 and one in Recon 1). The workflow further identified for both models several isolated internal loops that require further curation. The framework also highlighted the need for substrate channeling (in human) and ATP hydrolysis (in yeast) for the essential reaction catalyzed by phosphoribosylaminoimidazole carboxylase in purine metabolism. Finally, the framework highlighted differences in proline metabolism between yeast (cytosolic anabolism and mitochondrial catabolism) and humans (exclusively mitochondrial metabolism). We conclude that network-embedded thermodynamics facilitates the specification and validation of irreversibility constraints in compartmentalized metabolic models, at the same time providing further insight into network properties. PMID:25028891
Thermodynamic Model for the Ammonia-Water System
DEFF Research Database (Denmark)
Thomsen, Kaj; Rasmussen, Peter
2000-01-01
The ammonia-water system is described by the Extended UNIQUAC model, which is an electrolyte model, formed by combining the original UNIQUAC model, the Debye-Hückel law and the Soave-Redlich-Kwong equation of state. The model is limited to temperatures below the critical temperature of ammonia. V...
Software Engineering Tools for Scientific Models
Abrams, Marc; Saboo, Pallabi; Sonsini, Mike
2013-01-01
Software tools were constructed to address issues the NASA Fortran development community faces, and they were tested on real models currently in use at NASA. These proof-of-concept tools address the High-End Computing Program and the Modeling, Analysis, and Prediction Program. Two examples are the NASA Goddard Earth Observing System Model, Version 5 (GEOS-5) atmospheric model in Cell Fortran on the Cell Broadband Engine, and the Goddard Institute for Space Studies (GISS) coupled atmosphere- ocean model called ModelE, written in fixed format Fortran.
Bratberg, Johan
2005-01-01
The recent development of tool steels and high-speed steels has led to a significant increase in alloy additions, such as Co, Cr, Mo, N, V, and W. Knowledge about the phase relations in these multicomponent alloys, that is, the relative stability between different carbides or the solubility of different elements in the carbides and in the matrix phase, is essential for understanding the behaviour of these alloys in heat treatments. This information is also the basis for improving the properti...
Ben-Naim, Arieh
2017-01-01
This textbook introduces thermodynamics with a modern approach, starting from four fundamental physical facts (the atomic nature of matter, the indistinguishability of atoms and molecules of the same species, the uncertainty principle, and the existence of equilibrium states) and analyzing the behavior of complex systems with the tools of information theory, in particular with Shannon's measure of information (or SMI), which can be defined on any probability distribution. SMI is defined and its properties and time evolution are illustrated, and it is shown that the entropy is a particular type of SMI, i.e. the SMI related to the phase-space distribution for a macroscopic system at equilibrium. The connection to SMI allows the reader to understand what entropy is and why isolated systems follow the Second Law of Thermodynamics. The Second Llaw is also formulated for other systems, not thermally isolated and even open with respect to the transfer of particles. All the fundamental aspects of thermodynamics are d...
Fontenete, Sílvia; Guimarães, Nuno; Wengel, Jesper; Azevedo, Nuno Filipe
2016-01-01
The thermodynamics and kinetics of DNA hybridization, i.e. the process of self-assembly of one, two or more complementary nucleic acid strands, has been studied for many years. The appearance of the nearest-neighbor model led to several theoretical and experimental papers on DNA thermodynamics that provide reasonably accurate thermodynamic information on nucleic acid duplexes and allow estimation of the melting temperature. Because there are no thermodynamic models specifically developed to predict the hybridization temperature of a probe used in a fluorescence in situ hybridization (FISH) procedure, the melting temperature is used as a reference, together with corrections for certain compounds that are used during FISH. However, the quantitative relation between melting and experimental FISH temperatures is poorly described. In this review, various models used to predict the melting temperature for rRNA targets, for DNA oligonucleotides and for nucleic acid mimics (chemically modified oligonucleotides), will be addressed in detail, together with a critical assessment of how this information should be used in FISH.
Thermodynamic Model for Updraft Gasifier with External Recirculation of Pyrolysis Gas
Directory of Open Access Journals (Sweden)
Fajri Vidian
2016-01-01
Full Text Available Most of the thermodynamic modeling of gasification for updraft gasifier uses one process of decomposition (decomposition of fuel. In the present study, a thermodynamic model which uses two processes of decomposition (decomposition of fuel and char is used. The model is implemented in modification of updraft gasifier with external recirculation of pyrolysis gas to the combustion zone and the gas flowing out from the side stream (reduction zone in the updraft gasifier. The goal of the model obtains the influences of amount of recirculation pyrolysis gas fraction to combustion zone on combustible gas and tar. The significant results of modification updraft are that the increases amount of recirculation of pyrolysis gas will increase the composition of H2 and reduce the composition of tar; then the composition of CO and CH4 is dependent on equivalence ratio. The results of the model for combustible gas composition are compared with previous study.
Cao, Yuansheng; Gong, Zongping; Quan, H. T.
2015-06-01
Motivated by the recent proposed models of the information engine [Proc. Natl. Acad. Sci. USA 109, 11641 (2012), 10.1073/pnas.1204263109] and the information refrigerator [Phys. Rev. Lett. 111, 030602 (2013), 10.1103/PhysRevLett.111.030602], we propose a minimal model of the information pump and the information eraser based on enzyme kinetics. This device can either pump molecules against the chemical potential gradient by consuming the information to be encoded in the bit stream or (partially) erase the information initially encoded in the bit stream by consuming the Gibbs free energy. The dynamics of this model is solved exactly, and the "phase diagram" of the operation regimes is determined. The efficiency and the power of the information machine is analyzed. The validity of the second law of thermodynamics within our model is clarified. Our model offers a simple paradigm for the investigating of the thermodynamics of information processing involving the chemical potential in small systems.
Ali, Ashraf; Lovell, Michael
1995-01-01
This presentation summarizes the capabilities in the ANSYS program that relate to the computational modeling of tires. The power and the difficulties associated with modeling nearly incompressible rubber-like materials using hyperelastic constitutive relationships are highlighted from a developer's point of view. The topics covered include a hyperelastic material constitutive model for rubber-like materials, a general overview of contact-friction capabilities, and the acoustic fluid-structure interaction problem for noise prediction. Brief theoretical development and example problems are presented for each topic.
Ab Initio Thermodynamic Modeling of Electrified Metal-Oxide Interfaces
DEFF Research Database (Denmark)
Zeng, Zhenhua; Hansen, Martin Hangaard; Greeley, Jeff
2015-01-01
Solid oxide fuel cells are attractive devices in a sustainable energy context because of their fuel flexibility and potentially highly efficient conversion of chemical to electrical energy. The performance of the device is to a large extent determined by the atomic structure of the electrode...... the structural information can be used as a starting point for accurate calculations of the kinetics of fuel oxidation reactions, in particular the hydrogen oxidation reaction. More generally, we anticipate that the scheme will be a valuable theoretical tool to describe solid-solid interfaces. [Figure]...
Fisicaro, E; Compari, C; Braibanti, A
2010-10-01
The "hydrophobic hydration processes" can be satisfactorily interpreted on the basis of a common molecular model for water, consisting of two types of clusters, namely W(I) and W(II) accompanied by free molecules W(III). The principle of thermal equivalent dilution (TED) is the potent tool (Ergodic Hypothesis) employed to monitor the water equilibrium and to determine the number xi(w) of water molecules W(III) involved in each process. The hydrophobic hydration processes can be subdivided into two Classes: Class A includes those processes for which the transformation A(-xi(w)W(I)-->xi(w)W(II)+xi(w)W(III)+cavity) takes place with the formation of a cavity, by expulsion of xi(w) water molecules W(III) whereas Class B includes those processes for which the opposite transformation B(-xi(w)W(II)-xi(w)W(III)-->xi(w)W(I)-cavity) takes place with reduction of the cavity, by condensation of xi(w) water molecules W(III). The number xi(w) depends on the size of the reactants and measures the extent of the change in volume of the cavity. Disaggregating the thermodynamic functions DeltaH(app) and DeltaS(app) as the functions of T (or lnT) and xi(w) has enabled the separation of the thermodynamic functions into work and thermal components. The work functions DeltaG(Work), DeltaH(Work) and DeltaS(Work) only refer specifically to the hydrophobic effects of cavity formation or cavity reduction, respectively. The constant self-consistent unitary (xi(w)=1) work functions obtained from both large and small molecules indicate that the same unitary reaction is taking place, independent from the reactant size. The thermal functions DeltaH(Th) and DeltaS(Th) refer exclusively to the passage of state of water W(III). Essential mathematical algorithms are presented in the appendices. 2010 Elsevier B.V. All rights reserved.
Thermodynamic Models from Fluctuation Solution Theory Analysis of Molecular Simulations
DEFF Research Database (Denmark)
Christensen, Steen; Peters, Günther H.j.; Hansen, Flemming Yssing
2007-01-01
Fluctuation solution theory (FST) is employed to analyze results of molecular dynamics (MD) simulations of liquid mixtures. The objective is to generate parameters for macroscopic GE-models, here the modified Margules model. We present a strategy for choosing the number of parameters included...
Thermodynamics and structure of liquid surfaces investigated directly with surface analytical tools
Energy Technology Data Exchange (ETDEWEB)
Andersson, Gunther [Flinders Univ., Adelaide, SA (Australia). Centre for NanoScale Science and Technology; Morgner, Harald [Leipzig Univ. (Germany). Wilhelm Ostwald Inst. for Physical and Theoretical Chemistry
2017-06-15
Measuring directly the composition, the distribution of constituents as function of the depth and the orientation of molecules at liquid surfaces is essential for determining physicochemical properties of liquid surfaces. While the experimental tools that have been developed for analyzing solid surfaces can in principal be applied to liquid surfaces, it turned out that they had to be adjusted to the particular challenges imposed by liquid samples, e.g. by the unavoidable vapor pressure and by the mobility of the constituting atoms/molecules. In the present work it is shown, how electron spectroscopy and ion scattering spectroscopy have been used for analyzing liquid surfaces. The emphasis of this review is on using the structural information gained for determining the physicochemical properties of liquid surfaces. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Thermodynamic modeling of liquid–liquid phase change solvents for CO_{2} capture
DEFF Research Database (Denmark)
Waseem Arshad, Muhammad; von Solms, Nicolas; Thomsen, Kaj
2016-01-01
A thermodynamic model based on Extended UNIQUAC framework has been developed in this work for the de-mixing liquid–liquid phase change solvents, DEEA (2-(diethylamino)ethanol) and MAPA (3-(methylamino)propylamine). Parameter estimation was performed for two ternary systems, H2O-DEEA-CO2 and H2O......-MAPA-CO2, and a quaternary system, H2O-DEEA-MAPA-CO2 (phase change system), by using different types of experimental data (equilibrium and thermal) consisting of pure amine vapor pressure, vapor-liquid equilibrium, solid-liquid equilibrium, liquid–liquid equilibrium, excess enthalpy, and heat of absorption...... of CO2 in aqueous amine solutions. 94 model parameters and 6 thermodynamic properties were fitted to approximately 1500 experimental data. The developed model accurately represents the equilibrium and thermal data for the studied systems with a single unique set of parameters. The model parameters...
Modeling the thermodynamic response of metallic first walls
International Nuclear Information System (INIS)
Merrill, B.J.; Jones, J.L.
1982-01-01
The first wall material of a fusion device must have a high resistance to the erosion resulting from plasma disruptions. This erosion is a consequence of melting and surface vaporization produced by the energy deposition of the disrupting plasma. Predicting the extent of erosion has been the subject of various investigations, and as a result, the thermal modeling has evolved to include material melting, kinetics of surface evaporation, vaporized material transport, and plasma-vaporized material interactions. The significance of plasma-vapor interaction has yet to be fully resolved. The model presented by Hassanein suggests that the vapor attenuates the plasma ions, thereby shielding the wall surface and reducing the extent of vaporization. The erosion model developed by EG and G Idaho, Inc., has been extended to include a detailed model for plasma-vaporized material interaction. This paper presents the model, as well as predictions for plasma, vaporized material and first wall conditions during a disruption
Caravaca, Manuel; Sanchez-Andrada, Pilar; Soto, Antonio; Alajarin, Mateo
2014-12-14
The kinetic-thermodynamic switching point of a multistep process, whose reaction mechanism has been elucidated by DFT calculations, can be calculated by means of an efficient model based on the Network Simulation Method (NSM). This method can solve, fast and effectively, a difficult system of differential equations derived from a complex kinetic scheme by establishing a formal equivalence between the chemical system and an electrical network. The NSM employs very short simulation times to determine the dependence of the switching time on the temperature, a fundamental topic to take control over the product composition which has not been treated exhaustively so far, and that could be applied for synthetic purposes avoiding laborious and costly experimental trials.
Choukroun, M.
2010-12-01
pure water, and of more complex chemical systems relevant to icy moons (sulfate salts, ammonia, volatiles). This presentation will review phases of interest, their physical properties, and their influence on the geophysical behavior of icy satellites. Then the focus will shift toward thermodynamic tools (equations of state, thermodynamic models), which can provide the inputs required by geophysical models. The specific case of the modeling of the water and water-ammonia phase diagrams will be presented,8,9 along with its planetary implications, and anticipated developments to address the chemical complexity of icy satellites. The author acknowledges support from a NASA Postdoctoral Program Fellowship, administered by Oak Ridge Associated Universities. This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Government sponsorship acknowledged. References : 1Greeley et al., Icarus, 1998. 2McCord et al., J. Geophys. Res., 1999. 3Porco et al., Science, 2006. 4Waite et al., Nature, 2009. 5Toon et al., Icarus 1988. 6Sohl et al., Icarus 2002. 7Tobie et al., Icarus, 2005. 8Choukroun and Grasset, J. Chem. Phys, 2007. 9Choukroun and Grasset, J. Chem. Phys., in press.
Thermodynamically consistent description of criticality in models of correlated electrons
Czech Academy of Sciences Publication Activity Database
Janiš, Václav; Kauch, Anna; Pokorný, Vladislav
2017-01-01
Roč. 95, č. 4 (2017), s. 1-14, č. článku 045108. ISSN 2469-9950 R&D Projects: GA ČR GA15-14259S Institutional support: RVO:68378271 Keywords : conserving approximations * Anderson model * Hubbard model * parquet equations Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016
Xia, Ke; Shen, Guang-Bin; Zhu, Xiao-Qing
2015-06-14
32 F420 coenzyme models with alkylation of the three different N atoms (N1, N3 and N10) in the core structure (XFH(-)) were designed and synthesized and the thermodynamic driving forces (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the 32 XFH(-) releasing hydride ions, hydrogen atoms and electrons, the thermodynamic driving forces of the 32 XFH˙ releasing protons and hydrogen atoms and the thermodynamic driving forces of XF(-)˙ releasing electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The effects of the methyl group at N1, N3 and N10 and a negative charge on N1 and N10 atoms on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were examined; the results show that seating arrangements of the methyl group and the negative charge have remarkably different effects on the thermodynamic properties of the F420 coenzyme models and their related reaction intermediates. The effects of the substituents at C7 and C8 on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were also examined; the results show that the substituents at C7 and C8 have good Hammett linear free energy relationships with the six thermodynamic parameters. Meanwhile, a reasonable determination of possible reactions between members of the F420 family and NADH family in vivo was given according to a thermodynamic analysis platform constructed using the elementary step thermodynamic parameter of F420 coenzyme model 2FH(-) and NADH model MNAH releasing hydride ions in acetonitrile. The information disclosed in this work can not only fill a gap in the chemical thermodynamics of F420 coenzyme models as a class of very important organic sources of electrons, hydride ions, hydrogen atoms and protons, but also strongly promote the fast development of the chemistry and applications of F420 coenzyme.
Solubility modelling and thermodynamic dissolution functions of phthalimide in ten organic solvents
International Nuclear Information System (INIS)
Xu, Renjie; Wang, Jian; Han, Shuo; Du, Cunbin; Meng, Long; Zhao, Hongkun
2016-01-01
Highlights: • The solubility of phthalimide in ten organic solvents were determined. • The solubility were correlated with four thermodynamic models. • The dissolution thermodynamic properties of solution were obtained. - Abstract: In this work, a high performance liquid chromatography (HPLC) was employed to determine the solubilities of phthalimide in methanol, isopropanol, n-propanol, ethyl acetate, acetonitrile, i-butanol, n-butanol, toluene, acetone and ethanol at temperatures ranging from (283.15 to 318.15) K under 0.1 MPa. The solubility of phthalimide in a fixed solvent increases with an increase in temperature. At a certain temperature, the solubility in different solvents decreases according to the following order: acetone > ethyl acetate > (methanol, isopropanol, n-propanol, acetonitrile, i-butanol, n-butanol, ethanol) > toluene. Four models, modified Apelblat equation, λh equation, Wilson model and NRTL model were employed to correlate the solubility of phthalimide in the solvents studied. The evaluated solubilities provide better agreement with the modified Apelblat equation than the other three models. The four thermodynamic models are all acceptable for correlating the solubility of phthalimide in the solvents studied. Furthermore, the standard dissolution enthalpy and excess enthalpy of the solutions were obtained. The dissolution process of phthalimide in the selected solvents is discussed.
A molecular-thermodynamic model for polyelectrolyte solutions
Energy Technology Data Exchange (ETDEWEB)
Jiang, J.; Liu, H.; Hu, Y. [Thermodynamics Research Laboratory, East China University of Science and Technology, Shanghai 200237 (China); Prausnitz, J.M. [Department of Chemical Engineering, University of California, Berkeley, and Chemical Sciences Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)
1998-01-01
Polyelectrolyte solutions are modeled as freely tangent-jointed, charged hard-sphere chains and corresponding counterions in a continuum medium with permitivity {var_epsilon}. By adopting the sticky-point model, the Helmholtz function for polyelectrolyte solutions is derived through the r-particle cavity-correlation function (CCF) for chains of sticky, charged hard spheres. The r-CCF is approximated by a product of effective nearest-neighbor two-particle CCFs; these are determined from the hypernetted-chain and mean-spherical closures (HNC/MSA) inside and outside the hard core, respectively, for the integral equation theory for electrolytes. The colligative properties are given as explicit functions of a scaling parameter {Gamma} that can be estimated by a simple iteration procedure. Osmotic pressures, osmotic coefficients, and activity coefficients are calculated for model solutions with various chain lengths. They are in good agreement with molecular simulation and experimental results. {copyright} {ital 1998 American Institute of Physics.}
Energy Technology Data Exchange (ETDEWEB)
Krupka, Kenneth M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2010-09-01
Permanent storage of anthropogenic CO2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO2 sequestration. A review of thermodynamic data for CO2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO2 and CH4 gases, carbonate aqueous species, and carbonate minerals. Values of ΔfG298° and/or log Kr,298° are available for essentially all of these compounds. However, log Kr,T° or heat capacity values at temperatures above 298 K exist for less than
International Nuclear Information System (INIS)
Krupka, Kenneth M.; Cantrell, Kirk J.; McGrail, B. Peter
2010-01-01
Permanent storage of anthropogenic CO 2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO 2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO 2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO 2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO 2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO 2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO 2 sequestration. A review of thermodynamic data for CO 2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO 2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO 2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO 2 and CH 4 gases, carbonate aqueous species, and carbonate minerals. Values of Δ f G 298 o and/or log K r,298 o are available for essentially all of these compounds. However, log K r,T o or heat capacity values at temperatures above 298 K exist
Urbic, Tomaz
2017-02-01
In this paper we applied an analytical theory for the two dimensional dimerising fluid. We applied Wertheims thermodynamic perturbation theory (TPT) and integral equation theory (IET) for associative liquids to the dimerising model with arbitrary position of dimerising points from center of the particles. The theory was used to study thermodynamical and structural properties. To check the accuracy of the theories we compared theoretical results with corresponding results obtained by Monte Carlo computer simulations. The theories are accurate for the different positions of patches of the model at all values of the temperature and density studied. IET correctly predicts the pair correlation function of the model. Both TPT and IET are in good agreement with the Monte Carlo values of the energy, pressure, chemical potential, compressibility and ratios of free and bonded particles.
International Nuclear Information System (INIS)
Maevskii, K. K.; Kinelovskii, S. A.
2015-01-01
The numerical results of modeling of shock wave loading of mixtures with the SiO 2 component are presented. The TEC (thermodynamic equilibrium component) model is employed to describe the behavior of solid and porous multicomponent mixtures and alloys under shock wave loading. State equations of a Mie–Grüneisen type are used to describe the behavior of condensed phases, taking into account the temperature dependence of the Grüneisen coefficient, gas in pores is one of the components of the environment. The model is based on the assumption that all components of the mixture under shock-wave loading are in thermodynamic equilibrium. The calculation results are compared with the experimental data derived by various authors. The behavior of the mixture containing components with a phase transition under high dynamic loads is described
International Nuclear Information System (INIS)
Lothenbach, Barbara; Matschei, Thomas; Moeschner, Goeril; Glasser, Fred P.
2008-01-01
The composition of the phase assemblage and the pore solution of Portland cements hydrated between 0 and 60 deg. C were modelled as a function of time and temperature. The results of thermodynamic modelling showed a good agreement with the experimental data gained at 5, 20, and 50 deg. C. At 5 and at 20 deg. C, a similar phase assemblage was calculated to be present, while at approximately 50 deg. C, thermodynamic calculations predicted the conversion of ettringite and monocarbonate to monosulphate. Modelling showed that in Portland cements which have an Al 2 O 3 /SO 3 ratio of > 1.3 (bulk weight), above 50 deg. C monosulphate and monocarbonate are present. In Portland cements which contain less Al (Al 2 O 3 /SO 3 < 1.3), above 50 deg. C monosulphate and small amounts of ettringite are expected to persist. A good correlation between calculated porosity and measured compressive strength was observed
A Combined Thermodynamic and Kinetic Model for Barite Prediction at Oil Reservoir Conditions
DEFF Research Database (Denmark)
Zhen Wu, Bi Yun
dependence of Pitzer parameters for NaCl, Na2SO4 and BaCl2 were derived from published osmotic coefficient data (PhD Study 2). Furthermore, barite solubility was determined experimentally at 90 °C and pressures of 150 and 250 bar. Comparison of barite solubilities calculated with the Pitzer model...... of this research was to develop a model, based on thermodynamics and kinetics, for predicting barite precipitation rates in saline waters at the pressures and temperatures of oil bearing reservoirs, using the geochemical modelling code PHREEQC. This task is complicated by the conditions where traditional methods...... to 90 C at 1 bar of pressure. Resulting thermodynamic and kinetic parameters were combined and coupled with PHREEQC to predict precipitation scaling rates in three oil production wells, where barite has been observed. Average linear growth rates of 3, 2.5 and 2 mm of barite per year were estimated...
Thermodynamic and kinetic modeling of oxide precipitation in nanostructured ferritic alloys
International Nuclear Information System (INIS)
Barnard, L.; Cunningham, N.; Odette, G.R.; Szlufarska, I.; Morgan, D.
2015-01-01
The mechanical properties and radiation tolerance of nanostructured ferritic alloys rely on a dense population of nanometer-scale Y–Ti oxides. The stability of these nano-oxides during extended service is critical in high temperature applications. Here, a model framework is developed for the thermodynamics and kinetics of Y–Ti oxide nucleation, growth and coarsening. The model, which is based upon available thermodynamic and kinetic data as well as key density functional theory calculations, shows that nano-oxide nucleation and growth are highly driven and that pipe diffusion is the dominant mode of their coarsening, in agreement with previous analyses of experimental high temperature data. The model predicts that the nano-oxides are thermally stable for 80 or more years below 1175 K. This analysis also provides insights into the effect of O and Ti on nano-oxide sizes, and on optimization of alloy microstructure
International Nuclear Information System (INIS)
Zaghloul, Mofreh R.
2003-01-01
Flibe (2LiF-BeF2) is a molten salt that has been chosen as the coolant and breeding material in many design studies of the inertial confinement fusion (ICF) chamber. Flibe plasmas are to be generated in the ICF chamber in a wide range of temperatures and densities. These plasmas are more complex than the plasma of any single chemical species. Nevertheless, the composition and thermodynamic properties of the resulting flibe plasmas are needed for the gas dynamics calculations and the determination of other design parameters in the ICF chamber. In this paper, a simple consistent model for determining the detailed plasma composition and thermodynamic functions of high-temperature, fully dissociated and partially ionized flibe gas is presented and used to calculate different thermodynamic properties of interest to fusion applications. The computed properties include the average ionization state; kinetic pressure; internal energy; specific heats; adiabatic exponent, as well as the sound speed. The presented results are computed under the assumptions of local thermodynamic equilibrium (LTE) and electro-neutrality. A criterion for the validity of the LTE assumption is presented and applied to the computed results. Other attempts in the literature are assessed with their implied inaccuracies pointed out and discussed
Thermodynamic modeling of the formation and stability of small tin clusters and their ions
International Nuclear Information System (INIS)
Kodlaa, A.; Suliman, A.
2005-01-01
Based on the results of previous quantum-chemical study of electronic structure properties for neutral and single positively and negatively charged thin clusters in the size range of N 2-17 atoms, and on the thermodynamic laws, we have studied the thermodynamic properties of tin clusters and their ions. The characteristic amounts (cohesive enthalpy, formation enthalpy, fragmentation enthalpy, entropy and free enthalpy) for the formation and stability of these clusters at different temperatures were calculated. From the results, which are presented and discussed in this work, one can observe the following: The tin clusters Sn N (N=2-17) and their cations Sn + N and anions Sn - N are formed in the gas phase, and this agrees with experimental results. The clusters Sn 3 and Sn 1 0 are the most stable clusters of all. Here we also, find a correspondence with the results of the experimental studies. Our results go beyond that since we have found Sn 1 5 is also specially stable. By this thermodynamic study we could evaluate approximately the formation and stability of small neutral, single positively and negatively charged tin clusters. It has also allowed us to study the effects of the temperature on the formation and stability of these clusters. The importance of such study is not only what mentioned above, but it is also the first thermodynamic study for modeling the formation and stability of small tin clusters. (author)
Model for the Prediction of the Hydriding Thermodynamics of Pd-Rh-Co Ternary Alloys
Energy Technology Data Exchange (ETDEWEB)
Teter, D.F.; Thoma, D.J.
1999-03-01
A dilute solution model (with respect to the substitutional alloying elements) has been developed, which accurately predicts the hydride formation and decomposition thermodynamics and the storage capacities of dilute ternary Pd-Rh-Co alloys. The effect of varying the rhodium and cobalt compositions on the thermodynamics of hydride formation and decomposition and hydrogen capacity of several palladium-rhodium-cobalt ternary alloys has been investigated using pressure-composition (PC) isotherms. Alloying in the dilute regime (<10 at.%) causes the enthalpy for hydride formation to linearly decrease with increasing alloying content. Cobalt has a stronger effect on the reduction in enthalpy than rhodium for equivalent alloying amounts. Also, cobalt reduces the hydrogen storage capacity with increasing alloying content. The plateau thermodynamics are strongly linked to the lattice parameters of the alloys. A near-linear dependence of the enthalpy of hydride formation on the lattice parameter was observed for both the binary Pd-Rh and Pd-Co alloys, as well as for the ternary Pd-Rh-Co alloys. The Pd-5Rh-3Co (at. %) alloy was found to have similar plateau thermodynamics as a Pd-10Rh alloy, however, this ternary alloy had a diminished hydrogen storage capacity relative to Pd-10Rh.
Thermodynamics of trajectories of the one-dimensional Ising model
International Nuclear Information System (INIS)
Loscar, Ernesto S; Mey, Antonia S J S; Garrahan, Juan P
2011-01-01
We present a numerical study of the dynamics of the one-dimensional Ising model by applying the large-deviation method to describe ensembles of dynamical trajectories. In this approach trajectories are classified according to a dynamical order parameter and the structure of ensembles of trajectories can be understood from the properties of large-deviation functions, which play the role of dynamical free-energies. We consider both Glauber and Kawasaki dynamics, and also the presence of a magnetic field. For Glauber dynamics in the absence of a field we confirm the analytic predictions of Jack and Sollich about the existence of critical dynamical, or space–time, phase transitions at critical values of the 'counting' field s. In the presence of a magnetic field the dynamical phase diagram also displays first order transition surfaces. We discuss how these non-equilibrium transitions in the 1d Ising model relate to the equilibrium ones of the 2d Ising model. For Kawasaki dynamics we find a much simpler dynamical phase structure, with transitions reminiscent of those seen in kinetically constrained models
A thermodynamically consistent model of shape-memory alloys
Czech Academy of Sciences Publication Activity Database
Benešová, Barbora
2011-01-01
Roč. 11, č. 1 (2011), s. 355-356 ISSN 1617-7061 R&D Projects: GA ČR GAP201/10/0357 Institutional research plan: CEZ:AV0Z20760514 Keywords : slape memory alloys * model based on relaxation * thermomechanic coupling Subject RIV: BA - General Mathematics http://onlinelibrary.wiley.com/doi/10.1002/pamm.201110169/abstract
Thermodynamic modelling and optimization of a dual pressure ...
Indian Academy of Sciences (India)
The exergetic losses in CC system are compared with each other. The present DPRH HRSG model has been compared and validated with the plant and published data. Keywords. Combined cycle; dual pressure; deaerator; exergy analysis; heat recovery steam generator. 1. Introduction. Combined cycle (CC) power plants ...
Molecular Thermodynamic Modeling of Fluctuation Solution Theory Properties
DEFF Research Database (Denmark)
O’Connell, John P.; Abildskov, Jens
2013-01-01
for densities and gas solubilities, including ionic liquids and complex mixtures such as coal liquids. The approach is especially useful in systems with strong nonidealities. This chapter describes successful application of such modeling to a wide variety of systems treated over several decades and suggests how...
Estimation model for evaporative emissions from gasoline vehicles based on thermodynamics.
Hata, Hiroo; Yamada, Hiroyuki; Kokuryo, Kazuo; Okada, Megumi; Funakubo, Chikage; Tonokura, Kenichi
2018-03-15
In this study, we conducted seven-day diurnal breathing loss (DBL) tests on gasoline vehicles. We propose a model based on the theory of thermodynamics that can represent the experimental results of the current and previous studies. The experiments were performed using 14 physical parameters to determine the dependence of total emissions on temperature, fuel tank fill, and fuel vapor pressure. In most cases, total emissions after an apparent breakthrough were proportional to the difference between minimum and maximum environmental temperatures during the day, fuel tank empty space, and fuel vapor pressure. Volatile organic compounds (VOCs) were measured using a Gas Chromatography Mass Spectrometer and Flame Ionization Detector (GC-MS/FID) to determine the Ozone Formation Potential (OFP) of after-breakthrough gas emitted to the atmosphere. Using the experimental results, we constructed a thermodynamic model for estimating the amount of evaporative emissions after a fully saturated canister breakthrough occurred, and a comparison between the thermodynamic model and previous models was made. Finally, the total annual evaporative emissions and OFP in Japan were determined and compared by each model. Copyright © 2017 Elsevier B.V. All rights reserved.
Constraints of Compound Systems: Prerequisites for Thermodynamic Modeling Based on Shannon Entropy
Directory of Open Access Journals (Sweden)
Martin Pfleger
2014-05-01
Full Text Available Thermodynamic modeling of extensive systems usually implicitly assumes the additivity of entropy. Furthermore, if this modeling is based on the concept of Shannon entropy, additivity of the latter function must also be guaranteed. In this case, the constituents of a thermodynamic system are treated as subsystems of a compound system, and the Shannon entropy of the compound system must be subjected to constrained maximization. The scope of this paper is to clarify prerequisites for applying the concept of Shannon entropy and the maximum entropy principle to thermodynamic modeling of extensive systems. This is accomplished by investigating how the constraints of the compound system have to depend on mean values of the subsystems in order to ensure additivity. Two examples illustrate the basic ideas behind this approach, comprising the ideal gas model and condensed phase lattice systems as limiting cases of fluid phases. The paper is the first step towards developing a new approach for modeling interacting systems using the concept of Shannon entropy.
Characterizing real-space topology in Rice-Mele model by thermodynamics
You, Jia-Bin; Yang, Wanli
2018-01-01
The thermodynamic quantities which are related to energy-level statistics are used to characterize the real-space topology of the Rice-Mele model. Through studying the energy spectrum of the model under different boundary conditions, we found that the non-normalizable wave function for the infinite domain is reduced to the edge state adhered to the boundary. For the finite domain with symmetric boundary condition, the critical point for the topological phase transition is equal to the inverse of the domain length. In contrast, the critical point is zero for the semi-infinite domain. Additionally, the symmetry of the energy spectrum is found to be sensitive to the boundary conditions of the Rice-Mele model, and the emergence of the edge states as well as the topological phase transition can be reflected in the thermodynamic properties. A potentially practical scheme is proposed for simulating the Rice-Mele model and detecting the relevant thermodynamic quantities in the context of Bose-Einstein condensate.
Fagerström, Anton; Kocherbitov, Vitaly; Ruzgas, Tautgirdas; Westbye, Peter; Bergström, Karin; Engblom, Johan
2013-03-01
The main objective of this study was to investigate the mechanism of molecular transport across the cuticle of Clivia leaves. In vitro diffusion methodology was used to investigate the transport of a systemic fungicide, tebuconazole, over a model silicone membrane, enzymatically isolated cuticle membranes, and dermatomed leaves. It was shown that dermatomed leaves may replace enzymatically isolated cuticles. Furthermore, the effects of two surfactants, C(10)EO(7) and C(8)G(1.6), on the fungicide transport were investigated. Tebuconazole cuticle permeation was described using Fick's first law of diffusion, expressed by the thermodynamic activity of the solute in the membrane. A new method for calculation of diffusion coefficients in the membrane is proposed. To access the thermodynamic activity of the fungicide in the membranes, sorption isotherms of tebuconazole in the membrane materials studied were recorded. The thermodynamic activity of the fungicide in aqueous solutions was calculated from solubility data. For that purpose, the effect of surfactants on tebuconazole solubility was studied. The results show that addition of surfactants allows for higher concentrations of tebuconazole available for penetration. Nonetheless, at a fixed fungicide thermodynamic activity, all formulations produced the same flux over the silicone membrane independently on the fungicide concentration. This shows that the driving force across non-responding membranes is the gradient of thermodynamic activity, rather than the gradient of the fungicide concentration. In case of leaves, surfactants induced the same quantitative increase in both flux and diffusion coefficient of solute in the cuticle, while the cuticle-water partition coefficient was unaffected. Copyright © 2012 Elsevier B.V. All rights reserved.
M3FT-15OR0202212: SUBMIT SUMMARY REPORT ON THERMODYNAMIC EXPERIMENT AND MODELING
Energy Technology Data Exchange (ETDEWEB)
McMurray, Jake W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Brese, Robert G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Silva, Chinthaka M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Besmann, Theodore M. [Univ. of South Carolina, Columbia, SC (United States)
2015-09-01
Modeling the behavior of nuclear fuel with a physics-based approach uses thermodynamics for key inputs such as chemical potentials and thermal properties for phase transformation, microstructure evolution, and continuum transport simulations. Many of the lanthanide (Ln) elements and Y are high-yield fission products. The U-Y-O and U-Ln-O ternaries are therefore key subsystems of multi-component high-burnup fuel. These elements dissolve in the dominant urania fluorite phase affecting many of its properties. This work reports on an effort to assess the thermodynamics of the U-Pr-O and U-Y-O systems using the CALPHAD (CALculation of PHase Diagrams) method. The models developed within this framework are capable of being combined and extended to include additional actinides and fission products allowing calculation of the phase equilibria, thermochemical and material properties of multicomponent fuel with burnup.
Thermodynamics of QCD from Sakai-Sugimoto model
International Nuclear Information System (INIS)
Isono, Hiroshi; Mandal, Gautam; Morita, Takeshi
2015-01-01
Till date, the only consistent description of the deconfinement phase of the Sakai-Sugimoto model appears to be provided by the analysis of http://dx.doi.org/10.1007/JHEP09(2011)073. The current version of the analysis, however, has a subtlety regarding the monodromy of quarks around the Euclidean time circle. In this note, we revisit and resolve this issue by considering the effect of an imaginary baryon chemical potential on quark monodromies. With this ingredient, the proposal of http://dx.doi.org/10.1007/JHEP09(2011)073 for investigating finite temperature QCD using holography is firmly established. Additionally, our technique allows a holographic computation of the free energy as a function of the imaginary chemical potential in the deconfinement phase; we show that our result agrees with the corresponding formula obtained from perturbative QCD, namely the Roberge-Weiss potential.
Modeling and Computation of Thermodynamic Equilibrium for Mixtures of Inorganic and Organic Species
Caboussat, A.; Amundson, N. R.; He, J.; Martynenko, A. V.; Seinfeld, J. H.
2007-05-01
A series of modules has been developed in the atmospheric modeling community to predict the phase transition, crystallization and evaporation of inorganic aerosols. Modules for the computation of the thermodynamics of pure organic-containing aerosols have been developed more recently; however, the modeling of aerosols containing mixtures of inorganic and organic compounds has gathered less attention. We present here a model (UHAERO), that is flexible, efficient and rigorously computes the thermodynamic equilibrium of atmospheric particles containing inorganic and organic compounds. It is applied first to mixtures of inorganic electrolytes and dicarboxylic acids, and then to thermodynamic equilibria including crystallization and liquid-liquid phase separation. The model does not rely on any a priori specification of the phases present in certain atmospheric conditions. The multicomponent phase equilibrium for a closed organic aerosol system at constant temperature and pressure and for specified feeds is the solution to the equilibrium problem arising from the constrained minimization of the Gibbs free energy. For mixtures of inorganic electrolytes and dissociated organics, organic salts appear at equilibrium in the aqueous phase. In the general case, liquid-liquid phase separations happen and electrolytes dissociate in both aqueous and organic liquid phases. The Gibbs free energy is modeled by the UNIFAC model for the organic compounds, the PSC model for the inorganic constituents and a Pitzer model for interactions. The difficulty comes from the accurate estimation of interactions in the modeling of the activity coefficients. An accurate and efficient method for the computation of the minimum of energy is used to compute phase diagrams for mixtures of inorganic and organic species. Numerical results show the efficiency of the model for mixtures of inorganic electrolytes and organic acids, which make it suitable for insertion in global three-dimensional air quality
The european Trans-Tools transport model
Rooijen, T. van; Burgess, A.
2008-01-01
The paper presents the use of ArcGIS in the Transtools Transport Model, TRANS-TOOLS, created by an international consortium for the European Commission. The model describe passenger as well as freight transport in Europe with all medium and long distance modes (cars, vans, trucks, train, inland
System level modelling with open source tools
DEFF Research Database (Denmark)
Jakobsen, Mikkel Koefoed; Madsen, Jan; Niaki, Seyed Hosein Attarzadeh
, called ForSyDe. ForSyDe is available under the open Source approach, which allows small and medium enterprises (SME) to get easy access to advanced modeling capabilities and tools. We give an introduction to the design methodology through the system level modeling of a simple industrial use case, and we...
Application of the Thomas-Fermi statistical model to the thermodynamics of high density matter
International Nuclear Information System (INIS)
Martin, R.
1977-01-01
The Thomas-Fermi statistical model, from the N-body point of view is used in order to have systematic corrections to the T-Fermis equation. Approximate calculus methods are found from analytic study of the T-Fermis equation for non zero temperature. T-Fermis equation is solved with the code GOLEM written in FORTRAN V (UNIVAC). It also provides the thermodynamical quantities and a new method to calculate several isothermal tables. (Author) 24 refs
Application of the Thomas-Fermi statistical model to the thermodynamics of high density matter
International Nuclear Information System (INIS)
Martin, R.
1977-01-01
The Thomas-Fermi statistical model, from the N-body point of view is used in order to have systematic corrections to the T-Fermi's equation. Approximate calculus methods are found from analytic study of the T-Fermi's equation for non zero temperature. T-Fermi's equation is solved with the code ''Golem''written in Fortran V (Univac). It also provides the thermodynamical quantities and a new method to calculate several isothermal tables. (author) [es
Thermodynamic quantum critical behavior of the anisotropic Kondo necklace model
Energy Technology Data Exchange (ETDEWEB)
Reyes, D. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud, 150-Urca, 22290-180 RJ (Brazil)], E-mail: daniel@cbpf.br; Continentino, M.A. [Instituto de Fisica, Universidade Federal Fluminense, Campus da Praia Vermelha, Niteroi, RJ 24.210-340 (Brazil); Wang Hanting [Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)
2009-03-15
The Ising-like anisotropy parameter {delta} in the Kondo necklace model is analyzed using the bond-operator method at zero and finite temperatures for arbitrary d dimensions. A decoupling scheme on the double time Green's functions is used to find the dispersion relation for the excitations of the system. At zero temperature and in the paramagnetic side of the phase diagram, we determine the spin gap exponent {nu}z{approx}0.5 in three dimensions and anisotropy between 0{<=}{delta}{<=}1, a result consistent with the dynamic exponent z=1 for the Gaussian character of the bond-operator treatment. On the other hand, in the antiferromagnetic phase at low but finite temperatures, the line of Neel transitions is calculated for {delta}<<1. For d>2 it is only re-normalized by the anisotropy parameter and varies with the distance to the quantum critical point (QCP) |g| as, T{sub N}{proportional_to}|g|{sup {psi}} where the shift exponent {psi}=1/(d-1). Nevertheless, in two dimensions, a long-range magnetic order occurs only at T=0 for any {delta}<<1. In the paramagnetic phase, we also find a power law temperature dependence on the specific heat at the quantum critical trajectoryJ/t=(J/t){sub c}, T{yields}0. It behaves as C{sub V}{proportional_to}T{sup d} for {delta}{<=}1 and {approx}1, in concordance with the scaling theory for z=1.
Thermodynamical modeling of nuclear glasses: coexistence of amorphous phases
International Nuclear Information System (INIS)
Adjanor, G.
2007-11-01
Investigating the stability of borosilicate glasses used in the nuclear industry with respect to phase separation requires to estimate the Gibbs free energies of the various phases appearing in the material. In simulation, using current computational resources, a direct state-sampling of a glassy system with respect to its ensemble statistics is not ergodic and the estimated ensemble averages are not reliable. Our approach consists in generating, at a given cooling rate, a series of quenches, or paths connecting states of the liquid to states of the glass, and then in taking into account the probability to generate the paths leading to the different glassy states in ensembles averages. In this way, we introduce a path ensemble formalism and calculate a Landau free energy associated to a glassy meta-basin. This method was validated by accurately mapping the free energy landscape of a 38-atom glassy cluster. We then applied this approach to the calculation of the Gibbs free energies of binary amorphous Lennard-Jones alloys, and checked the correlation between the observed tendencies to order or to phase separate and the computed Gibbs free energies. We finally computed the driving force to phase separation in a simplified three-oxide nuclear glass modeled by a Born-Mayer-Huggins potential that includes a three-body term, and we compared the estimated quantities to the available experimental data. (author)
Directory of Open Access Journals (Sweden)
Wei Wang
2013-01-01
Full Text Available The precipitation of wax/solid paraffin during production, transportation, and processing of crude oil is a serious problem. It is essential to have a reliable model to predict the wax appearance temperature and the amount of solid precipitated at different conditions. This paper presents a work to predict the solid precipitation based on solid-liquid equilibrium with regular solution-molecular thermodynamic theory and characterization of the crude oil plus fraction. Due to the differences of solubility characteristics between solid and liquid phase, the solubility parameters of liquid and solid phase are calculated by a modified model. The heat capacity change between solid and liquid phase is considered and estimated in the thermodynamic model. An activity coefficient based thermodynamic method combined with two characteristic methods to calculate wax precipitation in crude oil, especially heavy oil, has been tested with experimental data. The results show that the wax appearance temperature and the amount of weight precipitated can be predicted well with the experimental data.
Liquidus Projection and Thermodynamic Modeling of a Sn-Ag-Zn System
Chen, Sinn-wen; Chiu, Wan-ting; Gierlotka, Wojciech; Chang, Jui-shen; Wang, Chao-hong
2017-12-01
Sn-Ag-Zn alloys are promising Pb-free solders. In this study, the Sn-Ag-Zn liquidus projection was determined, and the Sn-Ag-Zn thermodynamic modeling was developed. Various Sn-Ag-Zn alloys were prepared. Their as-cast microstructures and primary solidification phases were examined. The invariant reaction temperatures of the ternary Sn-Ag-Zn system were determined. The liquidus projection of the Sn-Ag-Zn ternary system was constructed. It was found that the Sn-Ag-Zn ternary system has eight primary solidification phases: ɛ2-AgZn3, γ-Ag5Zn8, β-AgZn, ζ-Ag4Sn, (Ag), ɛ1-Ag3Sn, β-(Sn) and (Zn) phases. There are eight ternary invariant reactions, and the liquid + (Ag) = β-AgZn + ζ-Ag4Sn reaction is of the highest temperature at 935.5 K. Thermodynamic modeling of the ternary Sn-Ag-Zn system was also carried out in this study based on the thermodynamic models of the three constituent binary systems and the experimentally determined liquidus projection. The liquidus projection and the isothermal sections are calculated. The calculated and experimentally determined liquidus projections are in good agreement.
Directory of Open Access Journals (Sweden)
Xuan L Liu
Full Text Available The phase relations and thermodynamic properties of the condensed Al-Co-Cr ternary alloy system are investigated using first-principles calculations based on density functional theory (DFT and phase-equilibria experiments that led to X-ray diffraction (XRD and electron probe micro-analysis (EPMA measurements. A thermodynamic description is developed by means of the calculations of phase diagrams (CALPHAD method using experimental and computational data from the present work and the literature. Emphasis is placed on modeling the bcc-A2, B2, fcc-γ, and tetragonal-σ phases in the temperature range of 1173 to 1623 K. Liquid, bcc-A2 and fcc-γ phases are modeled using substitutional solution descriptions. First-principles special quasirandom structures (SQS calculations predict a large bcc-A2 (disordered/B2 (ordered miscibility gap, in agreement with experiments. A partitioning model is then used for the A2/B2 phase to effectively describe the order-disorder transitions. The critically assessed thermodynamic description describes all phase equilibria data well. A2/B2 transitions are also shown to agree well with previous experimental findings.
International Nuclear Information System (INIS)
Nguyen, Tuong-Van; Elmegaard, Brian
2016-01-01
Highlights: • Six thermodynamic models used for evaluating gas liquefaction systems are compared. • Three gas liquefaction systems are modelled, assessed and optimised for each equation of state. • The predictions of thermophysical properties and energy flows are significantly different. • The GERG-2008 model is the only consistent one, while cubic, virial and statistical equations are unsatisfying. - Abstract: Natural gas liquefaction systems are based on refrigeration cycles – they consist of the same operations such as heat exchange, compression and expansion, but they have different layouts, components and working fluids. The design of these systems requires a preliminary simulation and evaluation of their performance. However, the thermodynamic models used for this purpose are characterised by different mathematical formulations, ranges of application and levels of accuracy. This may lead to inconsistent results when estimating hydrocarbon properties and assessing the efficiency of a given process. This paper presents a thorough comparison of six equations of state widely used in the academia and industry, including the GERG-2008 model, which has recently been adopted as an ISO standard for natural gases. These models are used to (i) estimate the thermophysical properties of a Danish natural gas, (ii) simulate, and (iii) optimise liquefaction systems. Three case studies are considered: a cascade layout with three pure refrigerants, a single mixed-refrigerant unit, and an expander-based configuration. Significant deviations are found between all property models, and in all case studies. The main discrepancies are related to the prediction of the energy flows (up to 7%) and to the heat exchanger conductances (up to 11%), and they are not systematic errors. The results illustrate the superiority of using the GERG-2008 model for designing gas processes in real applications, with the aim of reducing their energy use. They demonstrate as well that
Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions
International Nuclear Information System (INIS)
Kurepin, V. A.; Kulik, D. A.; Hitpold, A.; Nicolet, M.
2002-03-01
In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO 2 by incremental additions of O 2 in H 2 O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni phase, maintaining
Energy Technology Data Exchange (ETDEWEB)
Kruse, N.A., E-mail: natalie.kruse@ncl.ac.uk [Sir Joseph Swan Institute for Energy Research, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom); Younger, P.L. [Sir Joseph Swan Institute for Energy Research, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)
2009-07-15
Accurate modeling of changing geochemistry in mine water can be an important tool in post-mining site management. The Pollutant Sources and Sinks in Underground Mines (POSSUM) model and Pollutant Loadings Above Average Pyrite Influenced Geochemistry POSSUM (PLAYING POSSUM) model were developed using object-oriented programming techniques to simulate changing geochemistry in abandoned underground mines over time. The conceptual model was created to avoid significant simplifying assumptions that decrease the accuracy and defensibility of model solutions. POSSUM and PLAYING POSSUM solve for changes in flow rate and depth of flow using a finite difference hydrodynamics model then, subsequently, solve for geochemical changes at distinct points along the flow path. Geochemical changes are modeled based on a suite of 28 kinetically controlled mineral weathering reactions. Additional geochemical transformations due to reversible sorption, dissolution and precipitation of acid generating salts and mineral precipitation are also simulated using simplified expressions. Contaminant transport is simulated using a novel application of the Random-Walk method. By simulating hydrogeochemical changes with a physically and thermodynamically controlled model, the 'state of the art' in post-mining management can be advanced.
Energy Technology Data Exchange (ETDEWEB)
Hatzikioseyian, A.; Vidali, R.; Kousi, P.
2004-07-01
The present paper focuses on the modelling and thermodynamic analysis of the Multi Effect Distillation plant (MED) installed in PSA. the plant has been used as a demonstration unit for seawater desalination in many European Research projects. The authors have reviewed and developed a modelling and simulation program based on the design parameters of the plant. The model is based on the mass and energy balances for the streams flowing through each stage of the MED unit to predict the performance of the unit in terms of energy requirements. (Author) 5 refs.
Directory of Open Access Journals (Sweden)
Stuart P Wilson
2017-01-01
Full Text Available A thermodynamic model of thermoregulatory huddling interactions between endotherms is developed. The model is presented as a Monte Carlo algorithm in which animals are iteratively exchanged between groups, with a probability of exchanging groups defined in terms of the temperature of the environment and the body temperatures of the animals. The temperature-dependent exchange of animals between groups is shown to reproduce a second-order critical phase transition, i.e., a smooth switch to huddling when the environment gets colder, as measured in recent experiments. A peak in the rate at which group sizes change, referred to as pup flow, is predicted at the critical temperature of the phase transition, consistent with a thermodynamic description of huddling, and with a description of the huddle as a self-organising system. The model was subjected to a simple evolutionary procedure, by iteratively substituting the physiologies of individuals that fail to balance the costs of thermoregulation (by huddling in groups with the costs of thermogenesis (by contributing heat. The resulting tension between cooperative and competitive interactions was found to generate a phenomenon called self-organised criticality, as evidenced by the emergence of avalanches in fitness that propagate across many generations. The emergence of avalanches reveals how huddling can introduce correlations in fitness between individuals and thereby constrain evolutionary dynamics. Finally, a full agent-based model of huddling interactions is also shown to generate criticality when subjected to the same evolutionary pressures. The agent-based model is related to the Monte Carlo model in the way that a Vicsek model is related to an Ising model in statistical physics. Huddling therefore presents an opportunity to use thermodynamic theory to study an emergent adaptive animal behaviour. In more general terms, huddling is proposed as an ideal system for investigating the interaction
A re-examination of thermodynamic modelling of U-Ru binary phase diagram
Energy Technology Data Exchange (ETDEWEB)
Wang, L.C.; Kaye, M.H., E-mail: matthew.kaye@uoit.ca [University of Ontario Institute of Technology, Oshawa, ON (Canada)
2015-07-01
Ruthenium (Ru) is one of the more abundant fission products (FPs) both in fast breeder reactors and thermal reactors. Post irradiation examinations (PIE) show that both 'the white metallic phase' (MoTc-Ru-Rh-Pd) and 'the other metallic phase' (U(Pd-Rh-Ru)3) are present in spent nuclear fuels. To describe this quaternary system, binary subsystems of uranium (U) with Pd, Rh, and Ru are necessary. Presently, only the U-Ru system has been thermodynamically described but with some problems. As part of research on U-Ru-Rh-Pd quaternary system, an improved consistent thermodynamic model describing the U-Ru binary phase diagram has been obtained. (author)
A thermodynamic model for the attack behaviour in stainless steel clad oxide fuel pins
International Nuclear Information System (INIS)
Goetzmann, O.
1979-01-01
So far, post irradiation examination of burnt fuel pins has not revealed a clear cut picture of the cladding attack situation. For seemingly same conditions sometimes attack occurs, sometimes not. This model tries to depict the reaction possibilities along the inner cladding wall on the basis of thermodynamic facts in the fuel pin. It shows how the thermodynamic driving force for attack changes along the fuel column, and with different initial and operational conditions. Two criteria for attack are postulated: attack as a result of the direct reaction of reactive elements with cladding components; and attack as a result of the action of a special agent (CsOH). In defining a reaction potenial the oxygen potential, the temperature conditions (cladding temperature and fuel surface temperature), and the fission products are involved. For the determination of the oxygen potential at the cladding, three models for the redistribution of oxygen across the fuel/clad gap are offered. The effect of various parameters, like rod power, gap conductance, oxygen potential, inner wall temperature, on the thermodynamic potential for attack is analysed. (Auth.)
Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z
DEFF Research Database (Denmark)
Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.
1999-01-01
In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron...... sublattice and a hexagonal nitrogen sublattice formed by octahedral interstices of the Fe sublattice [1]. Two ground-state structures have been proposed for the ordered arrangement of the N atoms on their own sublattice [1], which were shown to be thermodynamically favourable [2]: configuration A for Fe2N1...... investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two configurations of LRO of the N atoms [2,3] was fitted to the N-absorption isotherm at 723 K and resulted in the occupancies of the sites of the nitrogen sublattice. A miscibility gap between...
Optima and bounds for irreversible thermodynamic processes
International Nuclear Information System (INIS)
Hoffmann, K.H.
1990-01-01
In this paper bounds and optima for irreversible thermodynamic processes and their application in different fields are discussed. The tools of finite time thermodynamics are presented and especially optimal control theory is introduced. These methods are applied to heat engines, including models of the Diesel engine and a light-driven engine. Further bounds for irreversible processes are introduced, discussing work deficiency and its relation to thermodynamic length. Moreover the problem of dissipation in systems composed of several subsystems is studied. Finally, the methods of finite time thermodynamics are applied to thermodynamic processes described on a more microscopic level. The process used as an example is simulated annealing. It is shown how optimal control theory is applied to find the optimal cooling schedule for this important stochastic optimization method
Energy Technology Data Exchange (ETDEWEB)
V. Glazoff, Michael; Charit, Indrajt; Sabharwall, Piyush
2014-09-17
An evaluation of thermodynamic aspects of hot corrosion of the superalloys Haynes 242 and HastelloyTM N in the eutectic mixtures of KF and ZrF4 is carried out for development of Advanced High Temperature Reactor (AHTR). This work models the behavior of several superalloys, potential candidates for the AHTR, using computational thermodynamics tool (ThermoCalc), leading to the development of thermodynamic description of the molten salt eutectic mixtures, and on that basis, mechanistic prediction of hot corrosion. The results from these studies indicated that the principal mechanism of hot corrosion was associated with chromium leaching for all of the superalloys described above. However, HastelloyTM N displayed the best hot corrosion performance. This was not surprising given it was developed originally to withstand the harsh conditions of molten salt environment. However, the results obtained in this study provided confidence in the employed methods of computational thermodynamics and could be further used for future alloy design efforts. Finally, several potential solutions to mitigate hot corrosion were proposed for further exploration, including coating development and controlled scaling of intermediate compounds in the KF-ZrF4 system.
International Nuclear Information System (INIS)
Hwang, Jeong Ui; Jang, Jong Jae; Jee, Jong Gi
1987-01-01
The contents of this book are thermodynamics on the law of thermodynamics, classical thermodynamics and molecule thermodynamics, basics of molecule thermodynamics, molecule and assembly partition function, molecule partition function, classical molecule partition function, thermodynamics function for ideal assembly in fixed system, thermodynamics function for ideal assembly in running system, Maxwell-Boltzmann's law of distribution, chemical equilibrium like calculation of equilibrium constant and theory of absolute reaction rate.
International Nuclear Information System (INIS)
Fang Zheng; Qiu Guanzhou
2007-01-01
A metallic solution model with adjustable parameter k has been developed to predict thermodynamic properties of ternary systems from those of its constituent three binaries. In the present model, the excess Gibbs free energy for a ternary mixture is expressed as a weighted probability sum of those of binaries and the k value is determined based on an assumption that the ternary interaction generally strengthens the mixing effects for metallic solutions with weak interaction, making the Gibbs free energy of mixing of the ternary system more negative than that before considering the interaction. This point is never considered in the models currently reported, where the only difference in a geometrical definition of molar values of components is considered that do not involve thermodynamic principles but are completely empirical. The current model describes the results of experiments very well, and by adjusting the k value also agrees with those from models used widely in the literature. Three ternary systems, Mg-Cu-Ni, Zn-In-Cd, and Cd-Bi-Pb are recalculated to demonstrate the method of determining k and the precision of the model. The results of the calculations, especially those in Mg-Cu-Ni system, are better than those predicted by the current models in the literature
Expansion of thermodynamic model of solute permeation through reverse osmosis membrane
International Nuclear Information System (INIS)
Nishimaki, Kenzo; Koyama, Akio
1994-01-01
Many studies have been performed on permeation mechanism of solute and solvent in membrane separation process like reverse osmosis or ultrafiltration, and several models of solute/solvent permeation through membrane are proposed. Among these models, Kedem and Katchalsky, based on the theory of thermodynamics of irreversible processes, formulated the one-solute permeation process in their mathematical model, which treats membrane as a black box, not giving consideration to membrane structure and to interaction between membrane material and permeates, viz. solute and solvent. According to this theory, the driving force of solute/solvent permeation through membrane is the difference of their chemical potential between both sides of membrane, and the linear phenomenological equation is applied to describing the relation between driving force and flux of solute/solvent. This equation can be applied to the irreversible process only when the process is almost in equilibrium. This condition is supposed to be satisfied in the solute/solvent permeation process through compact membrane with fine pores like reverse osmosis membrane. When reverse osmosis is applied to treatment process for liquid waste, which usually contains a lot of solutes as contaminants, we can not predict the behavior of contaminants by the above one-solute process model. In the case of multi-solutes permeation process for liquid waste, the number of parameter in thermodynamic model increases rapidly with the number of solute, because of coupling phenomenon among solutes. In this study, we expanded the above thermodynamic model to multi-solute process applying operational calculus to the differential equations which describe the irreversible process of the system, and expressed concisely solute concentration vector as a matrix product. In this way, we predict the behavior of solutes in multi-solutes process, using values of parameters obtained in two-solutes process. (author)
Beretta, Gian Paolo
2014-10-01
By suitable reformulations, we cast the mathematical frameworks of several well-known different approaches to the description of nonequilibrium dynamics into a unified formulation valid in all these contexts, which extends to such frameworks the concept of steepest entropy ascent (SEA) dynamics introduced by the present author in previous works on quantum thermodynamics. Actually, the present formulation constitutes a generalization also for the quantum thermodynamics framework. The analysis emphasizes that in the SEA modeling principle a key role is played by the geometrical metric with respect to which to measure the length of a trajectory in state space. In the near-thermodynamic-equilibrium limit, the metric tensor is directly related to the Onsager's generalized resistivity tensor. Therefore, through the identification of a suitable metric field which generalizes the Onsager generalized resistance to the arbitrarily far-nonequilibrium domain, most of the existing theories of nonequilibrium thermodynamics can be cast in such a way that the state exhibits the spontaneous tendency to evolve in state space along the path of SEA compatible with the conservation constraints and the boundary conditions. The resulting unified family of SEA dynamical models is intrinsically and strongly consistent with the second law of thermodynamics. The non-negativity of the entropy production is a general and readily proved feature of SEA dynamics. In several of the different approaches to nonequilibrium description we consider here, the SEA concept has not been investigated before. We believe it defines the precise meaning and the domain of general validity of the so-called maximum entropy production principle. Therefore, it is hoped that the present unifying approach may prove useful in providing a fresh basis for effective, thermodynamically consistent, numerical models and theoretical treatments of irreversible conservative relaxation towards equilibrium from far nonequilibrium
Eichhorn, Ralf; Aurell, Erik
2014-04-01
'Stochastic thermodynamics as a conceptual framework combines the stochastic energetics approach introduced a decade ago by Sekimoto [1] with the idea that entropy can consistently be assigned to a single fluctuating trajectory [2]'. This quote, taken from Udo Seifert's [3] 2008 review, nicely summarizes the basic ideas behind stochastic thermodynamics: for small systems, driven by external forces and in contact with a heat bath at a well-defined temperature, stochastic energetics [4] defines the exchanged work and heat along a single fluctuating trajectory and connects them to changes in the internal (system) energy by an energy balance analogous to the first law of thermodynamics. Additionally, providing a consistent definition of trajectory-wise entropy production gives rise to second-law-like relations and forms the basis for a 'stochastic thermodynamics' along individual fluctuating trajectories. In order to construct meaningful concepts of work, heat and entropy production for single trajectories, their definitions are based on the stochastic equations of motion modeling the physical system of interest. Because of this, they are valid even for systems that are prevented from equilibrating with the thermal environment by external driving forces (or other sources of non-equilibrium). In that way, the central notions of equilibrium thermodynamics, such as heat, work and entropy, are consistently extended to the non-equilibrium realm. In the (non-equilibrium) ensemble, the trajectory-wise quantities acquire distributions. General statements derived within stochastic thermodynamics typically refer to properties of these distributions, and are valid in the non-equilibrium regime even beyond the linear response. The extension of statistical mechanics and of exact thermodynamic statements to the non-equilibrium realm has been discussed from the early days of statistical mechanics more than 100 years ago. This debate culminated in the development of linear response
Directory of Open Access Journals (Sweden)
Magda Waldemar
2017-12-01
Full Text Available This paper deals with mathematical modelling of a seabed layer in the thermodynamic analysis of a submarine pipeline buried in seabed sediments. The existing seabed soil models: a “soil ring” and a semi-infinite soil layer are discussed in a comparative analysis of the shape factor of a surrounding soil layer. The meaning of differences in the heat transfer coefficient of a soil layer is illustrated based on a computational example of the longitudinal temperaturę profile of a -kilometer long crude oil pipeline buried in seabed sediments.
A thermodynamic/mass-transport model for the release of ruthenium from irradiated fuel
International Nuclear Information System (INIS)
Garisto, F.; Iglesias, F.C.; Hunt, C.E.L.
1990-01-01
Some postulated nuclear reactor accidents lead to fuel failures and hence release of fission products into the primary heat transport system (PHTS). To determine the consequences of such accidents, it is important to understand the behavior of fission products both in the PHTS and in the reactor containment building. Ruthenium metal has a high boiling point and is nonvolatile under reducing conditions. However, under oxidizing conditions ruthenium can form volatile oxides at relatively low temperatures and, hence, could escape from failed fuel and enter the containment building. The ruthenium radioisotope Ru-106 presents a potentially significant health risk if it is released outside the reactor containment building. Consequently, it is important to understand the behavior of ruthenium during a nuclear reactor accident. The authors review the thermodynamic behavior of ruthenium at high temperatures. The qualitative behavior of ruthenium, predicted using thermodynamic calculations, is then compared with experimental results from the Chalk River Nuclear Laboratories (CRNL). Finally, a simple thermodynamic/mass-transport model is proposed to explain the release behavior of ruthenium in a steam atmosphere
DEFF Research Database (Denmark)
Herslund, Peter Jørgensen; Daraboina, Nagu; Thomsen, Kaj
2014-01-01
.A thermodynamic model, based on the van der Waals–Platteeuw model and the cubic-plus-association equation of state is applied to model the mixed promoter system. The model accurately predicts the data measured in this work. Furthermore, the model explains the synergistic effect by the fact that tetrahydrofuran...
Vrabec, Jadran; Kedia, Gaurav Kumar; Buchhauser, Ulrich; Meyer-Pittroff, Roland; Hasse, Hans
2009-02-01
For the design and optimization of CO 2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N 2 + O 2 + CO 2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N 2 and O 2 in CO 2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO 2-rich region.
Kou, Jisheng
2017-12-09
A general diffuse interface model with a realistic equation of state (e.g. Peng-Robinson equation of state) is proposed to describe the multi-component two-phase fluid flow based on the principles of the NVT-based framework which is an attractive alternative recently over the NPT-based framework to model the realistic fluids. The proposed model uses the Helmholtz free energy rather than Gibbs free energy in the NPT-based framework. Different from the classical routines, we combine the first law of thermodynamics and related thermodynamical relations to derive the entropy balance equation, and then we derive a transport equation of the Helmholtz free energy density. Furthermore, by using the second law of thermodynamics, we derive a set of unified equations for both interfaces and bulk phases that can describe the partial miscibility of multiple fluids. A relation between the pressure gradient and chemical potential gradients is established, and this relation leads to a new formulation of the momentum balance equation, which demonstrates that chemical potential gradients become the primary driving force of fluid motion. Moreover, we prove that the proposed model satisfies the total (free) energy dissipation with time. For numerical simulation of the proposed model, the key difficulties result from the strong nonlinearity of Helmholtz free energy density and tight coupling relations between molar densities and velocity. To resolve these problems, we propose a novel convex-concave splitting of Helmholtz free energy density and deal well with the coupling relations between molar densities and velocity through very careful physical observations with a mathematical rigor. We prove that the proposed numerical scheme can preserve the discrete (free) energy dissipation. Numerical tests are carried out to verify the effectiveness of the proposed method.
Numerical simulation of a thermodynamically consistent four-species tumor growth model.
Hawkins-Daarud, Andrea; van der Zee, Kristoffer G; Oden, J Tinsley
2012-01-01
In this paper, we develop a thermodynamically consistent four-species model of tumor growth on the basis of the continuum theory of mixtures. Unique to this model is the incorporation of nutrient within the mixture as opposed to being modeled with an auxiliary reaction-diffusion equation. The formulation involves systems of highly nonlinear partial differential equations of surface effects through diffuse-interface models. A mixed finite element spatial discretization is developed and implemented to provide numerical results demonstrating the range of solutions this model can produce. A time-stepping algorithm is then presented for this system, which is shown to be first order accurate and energy gradient stable. The results of an array of numerical experiments are presented, which demonstrate a wide range of solutions produced by various choices of model parameters.
Web tools for predictive toxicology model building.
Jeliazkova, Nina
2012-07-01
The development and use of web tools in chemistry has accumulated more than 15 years of history already. Powered by the advances in the Internet technologies, the current generation of web systems are starting to expand into areas, traditional for desktop applications. The web platforms integrate data storage, cheminformatics and data analysis tools. The ease of use and the collaborative potential of the web is compelling, despite the challenges. The topic of this review is a set of recently published web tools that facilitate predictive toxicology model building. The focus is on software platforms, offering web access to chemical structure-based methods, although some of the frameworks could also provide bioinformatics or hybrid data analysis functionalities. A number of historical and current developments are cited. In order to provide comparable assessment, the following characteristics are considered: support for workflows, descriptor calculations, visualization, modeling algorithms, data management and data sharing capabilities, availability of GUI or programmatic access and implementation details. The success of the Web is largely due to its highly decentralized, yet sufficiently interoperable model for information access. The expected future convergence between cheminformatics and bioinformatics databases provides new challenges toward management and analysis of large data sets. The web tools in predictive toxicology will likely continue to evolve toward the right mix of flexibility, performance, scalability, interoperability, sets of unique features offered, friendly user interfaces, programmatic access for advanced users, platform independence, results reproducibility, curation and crowdsourcing utilities, collaborative sharing and secure access.
A Thermodynamic Library for Simulation and Optimization of Dynamic Processes
DEFF Research Database (Denmark)
Ritschel, Tobias Kasper Skovborg; Gaspar, Jozsef; Jørgensen, John Bagterp
2017-01-01
Process system tools, such as simulation and optimization of dynamic systems, are widely used in the process industries for development of operational strategies and control for process systems. These tools rely on thermodynamic models and many thermodynamic models have been developed for different...... compounds and mixtures. However, rigorous thermodynamic models are generally computationally intensive and not available as open-source libraries for process simulation and optimization. In this paper, we describe the application of a novel open-source rigorous thermodynamic library, ThermoLib, which...... is designed for dynamic simulation and optimization of vapor-liquid processes. ThermoLib is implemented in Matlab and C and uses cubic equations of state to compute vapor and liquid phase thermodynamic properties. The novelty of ThermoLib is that it provides analytical first and second order derivatives...
Thermodynamic modeling of Al–U–X (X = Si,Zr)
International Nuclear Information System (INIS)
Rabin, Daniel; Shneck, Roni Z.; Rafailov, Gennady; Dahan, Isaac; Meshi, Louisa; Brosh, Eli
2015-01-01
Highlights: • Thermodynamic models of the U–Al–Si and U–Al–Zr systems were constructed. • The extrapolation methods of the ternary liquid phase were explored. • The order–disorder transition of the U(Al,Si) 3 phase was modeled. • New experiments fix the composition of U(Al,Si) 3 in equilibrium with Al and Si. • Effects of Si on microstructures of solidified U–Al alloys are clarified. - Abstract: Thermodynamic models are constructed for the U–Al–Si and U–A–Zr ternary alloy systems using the CALPHAD (CALculation of PHAse Diagrams) method. For the U–Al–Zr system the modeling covers only the aluminum-rich corner (from 100 at% to 67 at% Al) and is based only on literature data. For the U–Al–Si system, the whole range of compositions is covered and new key experiments were done in the uranium-poor region of the U–Al–Si system. These experiments have shown that under conditions of equilibrium with Al and Si, the Si-content of the U(Al,Si) 3 is significantly higher than reported by earlier works. Different extrapolation methods were tried for the Gibbs energy of the liquid phase. However, it was found that for the U–Al–Si and U–Al–Zr systems, symmetric Muggianu method and the asymmetric method by Hillert give similar predictions. The constructed thermodynamic database was investigated by calculating isothermal sections, vertical sections and the liquidus projection. The calculated diagrams are in reasonable agreement with experimental data. Finally, solidification simulation (Scheil simulation) was done in order to assess the phases obtained in solidification as a function of the silicon addition to U–Al alloys
Vlcek, L.; Rother, G.; Chialvo, A.; Cole, D. R.
2011-12-01
Injection of CO2 into geologic formations has been proposed as a key element to reduce the impact of greenhouse gases emissions. Quantitative understanding of CO2 adsorption in porous mineral environments at thermodynamic conditions relevant to proposed sequestration sites is thus a prerequisite for the assessment of their viability. In this study we use a combination of neutron scattering, adsorption experiments, and computer modeling to investigate the thermodynamics of near-critical carbon dioxide in the pores of SiO2 aerogel, which serves as a model of a high-porosity reservoir rock. Small angle neutron scattering (SANS) experiments provide input for the optimization of the computer model of the aerogel matrix, and also serve as a sensitive probe of local density changes of confined CO2 as a function of external pressure. Additional details of the aerogel basic building blocks and SiO2 surface are derived from TEM images. An independent source of global adsorption data is obtained from gravimetric experiments. The structural and thermodynamic aspects of CO2 sorption are linked using computer simulations, which include the application of the optimized diffusion limited cluster-cluster aggregation algorithm (DLCA), classical density functional theory (DFT) modeling of large-scale CO2 density profiles, and molecular dynamics simulations of the details of interactions between CO2 molecules and the amorphous silica surfaces. This integrated approach allows us to span scales ranging from 1Å to 1μm, as well as to infer the detailed structure of silica threads forming the framework of the silica matrix.
Thermodynamic and kinetic modelling of fuel oxidation behaviour in operating defective fuel
International Nuclear Information System (INIS)
Lewis, B.J.; Thompson, W.T.; Akbari, F.; Thompson, D.M.; Thurgood, C.; Higgs, J.
2004-01-01
A theoretical treatment has been developed to predict the fuel oxidation behaviour in operating defective nuclear fuel elements. The equilibrium stoichiometry deviation in the hyper-stoichiometric fuel has been derived from thermodynamic considerations using a self-consistent set of thermodynamic properties for the U-O system, which emphasizes replication of solubilities and three-phase invariant conditions displayed in the U-O binary phase diagram. The kinetics model accounts for multi-phase transport including interstitial oxygen diffusion in the solid and gas-phase transport of hydrogen and steam in the fuel cracks. The fuel oxidation model is further coupled to a heat conduction model to account for the feedback effect of a reduced thermal conductivity in the hyper-stoichiometric fuel. A numerical solution has been developed using a finite-element technique with the FEMLAB software package. The model has been compared to available data from several in-reactor X-2 loop experiments with defective fuel conducted at the Chalk River Laboratories. The model has also been benchmarked against an O/U profile measurement for a spent defective fuel element discharged from a commercial reactor
A deformation and thermodynamic model for hydride precipitation kinetics in spent fuel cladding
International Nuclear Information System (INIS)
Stout, R.B.
1989-10-01
Hydrogen is contained in the Zircaloy cladding of spent fuel rods from nuclear reactors. All the spent fuel rods placed in a nuclear waste repository will have a temperature history that decreases toward ambient; and as a result, most all of the hydrogen in the Zircaloy will eventually precipitate as zirconium hydride platelets. A model for the density of hydride platelets is a necessary sub-part for predicting Zircaloy cladding failure rate in a nuclear waste repository. A model is developed to describe statistically the hydride platelet density, and the density function includes the orientation as a physical attribute. The model applies concepts from statistical mechanics to derive probable deformation and thermodynamic functionals for cladding material response that depend explicitly on the hydride platelet density function. From this model, hydride precipitation kinetics depend on a thermodynamic potential for hydride density change and on the inner product of a stress tensor and a tensor measure for the incremental volume change due to hydride platelets. The development of a failure response model for Zircaloy cladding exposed to the expected conditions in a nuclear waste repository is supported by the US DOE Yucca Mountain Project. 19 refs., 3 figs
Chen, Zhong-Xiu; Wu, Wen; Zhang, Wei-Bin; Deng, Shao-Ping
2011-09-01
The thermodynamics of the mimetic interaction of lactisole and sweeteners with fullerenols as a synthetic sweet receptor model was elucidated by Isothermal Titration Calorimetry (ITC) technique. The presence of lactisole resulted in great differences in thermodynamics of the sweeteners binding with fullerenols in which lactisole led to much more entropy contribution to the free energy compared with the interaction of sweeteners with fullerenols. Two interaction equilibrium states were found in ITC titration profiles and competitive binding of lactisole and sweeteners with fullerenols was disclosed. Our results indicated that the larger value of the ratio of two equilibrium constant K1/K2, the more effectively lactisole inhibited the sweetness of the sweetener. The combined results of sensory evaluation and ITC thermodynamics revealed that introducing a synthetic receptor model to interact with the sweeteners and inhibitors helps to understand the inhibition mechanism and the thermodynamic basis for the initiation of sweetness inhibition. Copyright © 2011 Elsevier Ltd. All rights reserved.
Graphical tools for model selection in generalized linear models.
Murray, K; Heritier, S; Müller, S
2013-11-10
Model selection techniques have existed for many years; however, to date, simple, clear and effective methods of visualising the model building process are sparse. This article describes graphical methods that assist in the selection of models and comparison of many different selection criteria. Specifically, we describe for logistic regression, how to visualize measures of description loss and of model complexity to facilitate the model selection dilemma. We advocate the use of the bootstrap to assess the stability of selected models and to enhance our graphical tools. We demonstrate which variables are important using variable inclusion plots and show that these can be invaluable plots for the model building process. We show with two case studies how these proposed tools are useful to learn more about important variables in the data and how these tools can assist the understanding of the model building process. Copyright © 2013 John Wiley & Sons, Ltd.
Animal models: an important tool in mycology.
Capilla, Javier; Clemons, Karl V; Stevens, David A
2007-12-01
Animal models of fungal infections are, and will remain, a key tool in the advancement of the medical mycology. Many different types of animal models of fungal infection have been developed, with murine models the most frequently used, for studies of pathogenesis, virulence, immunology, diagnosis, and therapy. The ability to control numerous variables in performing the model allows us to mimic human disease states and quantitatively monitor the course of the disease. However, no single model can answer all questions and different animal species or different routes of infection can show somewhat different results. Thus, the choice of which animal model to use must be made carefully, addressing issues of the type of human disease to mimic, the parameters to follow and collection of the appropriate data to answer those questions being asked. This review addresses a variety of uses for animal models in medical mycology. It focuses on the most clinically important diseases affecting humans and cites various examples of the different types of studies that have been performed. Overall, animal models of fungal infection will continue to be valuable tools in addressing questions concerning fungal infections and contribute to our deeper understanding of how these infections occur, progress and can be controlled and eliminated.
M. M. Clark; T. H. Fletcher; R. R. Linn
2010-01-01
The chemical processes of gas phase combustion in wildland fires are complex and occur at length-scales that are not resolved in computational fluid dynamics (CFD) models of landscape-scale wildland fire. A new approach for modelling fire chemistry in HIGRAD/FIRETEC (a landscape-scale CFD wildfire model) applies a mixtureâ fraction model relying on thermodynamic...
Methods to Increase the Robustness of Finite-Volume Flow Models in Thermodynamic Systems
Directory of Open Access Journals (Sweden)
Sylvain Quoilin
2014-03-01
Full Text Available This paper addresses the issues linked to simulation failures during integration in finite-volume flow models, especially those involving a two-phase state. This kind of model is particularly useful when modeling 1D heat exchangers or piping, e.g., in thermodynamic cycles involving a phase change. Issues, such as chattering or stiff systems, can lead to low simulation speed, instabilities and simulation failures. In the particular case of two-phase flow models, they are usually linked to a discontinuity in the density derivative between the liquid and two-phase zones. In this work, several methods to tackle numerical problems are developed, described, implemented and compared. In addition, methods available in the literature are also implemented and compared to the proposed approaches. Results suggest that the robustness of the models can be significantly increased with these different methods, at the price of a small increase of the error in the mass and energy balances.
Thermodynamic modelling of a recompression CO2 power cycle for low temperature waste heat recovery
International Nuclear Information System (INIS)
Banik, Shubham; Ray, Satyaki; De, Sudipta
2016-01-01
Highlights: • Thermodynamic model for recompression T-CO 2 is developed. • Energetic and exergetic analysis compared with S-CO 2 and Reg. Brayton cycle. • Maximum efficiency of 13.6% is obtained for T-CO 2 cycle. • Optimum recompression ratio of 0.48 is obtained for minimum irreversibility. • Reg. Brayton has better efficiency, T-CO 2 offers minimum irreversibility. - Abstract: Due to the rising prices of conventional fossil fuels, increasing the overall thermal efficiency of a power plant is essential. One way of doing this is waste heat recovery. This recovery is most difficult for low temperature waste heat, below 240 °C, which also covers majority of the waste heat source. Carbon dioxide, with its low critical temperature and pressure, offers an advantage over ozone-depleting refrigerants used in Organic Rankine Cycles (ORCs) and hence is most suitable for the purpose. This paper introduces parametric optimization of a transcritical carbon dioxide (T-CO 2 ) power cycle which recompresses part of the total mass flow of working fluid before entering the precooler, thereby showing potential for higher cycle efficiency. Thermodynamic model for a recompression T-CO 2 power cycle has been developed with waste heat source of 2000 kW and at a temperature of 200 °C. Results obtained from this model are analysed to estimate effects on energetic and exergetic performances of the power cycle with varying pressure and mass recompression ratio. Higher pressure ratio always improves thermodynamic performance of the cycle – both energetic and exergetic. Higher recompression ratio also increases exergetic efficiency of the cycle. However, it increases energy efficiency, only if precooler inlet temperature remains constant. Maximum thermal efficiency of the T-CO 2 cycle with a recompression ratio of 0.26 has been found to be 13.6%. To minimize total irreversibility of the cycle, an optimum ratio of 0.48 was found to be suitable.
A molecular thermodynamic model for the stability of hepatitis B capsids
Energy Technology Data Exchange (ETDEWEB)
Kim, Jehoon; Wu, Jianzhong, E-mail: jwu@engr.ucr.edu [Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521 (United States)
2014-06-21
Self-assembly of capsid proteins and genome encapsidation are two critical steps in the life cycle of most plant and animal viruses. A theoretical description of such processes from a physiochemical perspective may help better understand viral replication and morphogenesis thus provide fresh insights into the experimental studies of antiviral strategies. In this work, we propose a molecular thermodynamic model for predicting the stability of Hepatitis B virus (HBV) capsids either with or without loading nucleic materials. With the key components represented by coarse-grained thermodynamic models, the theoretical predictions are in excellent agreement with experimental data for the formation free energies of empty T4 capsids over a broad range of temperature and ion concentrations. The theoretical model predicts T3/T4 dimorphism also in good agreement with the capsid formation at in vivo and in vitro conditions. In addition, we have studied the stability of the viral particles in response to physiological cellular conditions with the explicit consideration of the hydrophobic association of capsid subunits, electrostatic interactions, molecular excluded volume effects, entropy of mixing, and conformational changes of the biomolecular species. The course-grained model captures the essential features of the HBV nucleocapsid stability revealed by recent experiments.
A molecular thermodynamic model for the stability of hepatitis B capsids
Kim, Jehoon; Wu, Jianzhong
2014-06-01
Self-assembly of capsid proteins and genome encapsidation are two critical steps in the life cycle of most plant and animal viruses. A theoretical description of such processes from a physiochemical perspective may help better understand viral replication and morphogenesis thus provide fresh insights into the experimental studies of antiviral strategies. In this work, we propose a molecular thermodynamic model for predicting the stability of Hepatitis B virus (HBV) capsids either with or without loading nucleic materials. With the key components represented by coarse-grained thermodynamic models, the theoretical predictions are in excellent agreement with experimental data for the formation free energies of empty T4 capsids over a broad range of temperature and ion concentrations. The theoretical model predicts T3/T4 dimorphism also in good agreement with the capsid formation at in vivo and in vitro conditions. In addition, we have studied the stability of the viral particles in response to physiological cellular conditions with the explicit consideration of the hydrophobic association of capsid subunits, electrostatic interactions, molecular excluded volume effects, entropy of mixing, and conformational changes of the biomolecular species. The course-grained model captures the essential features of the HBV nucleocapsid stability revealed by recent experiments.
Modeling ARRM Xenon Tank Pressurization Using 1D Thermodynamic and Heat Transfer Equations
Gilligan, Patrick; Tomsik, Thomas
2016-01-01
As a first step in understanding what ground support equipment (GSE) is required to provide external cooling during the loading of 5,000 kg of xenon into 4 aluminum lined composite overwrapped pressure vessels (COPVs), a modeling analysis was performed using Microsoft Excel. The goals of the analysis were to predict xenon temperature and pressure throughout loading at the launch facility, estimate the time required to load one tank, and to get an early estimate of what provisions for cooling xenon might be needed while the tanks are being filled. The model uses the governing thermodynamic and heat transfer equations to achieve these goals. Results indicate that a single tank can be loaded in about 15 hours with reasonable external coolant requirements. The model developed in this study was successfully validated against flight and test data. The first data set is from the Dawn mission which also utilizes solar electric propulsion with xenon propellant, and the second is test data from the rapid loading of a hydrogen cylindrical COPV. The main benefit of this type of model is that the governing physical equations using bulk fluid solid temperatures can provide a quick and accurate estimate of the state of the propellant throughout loading which is much cheaper in terms of computational time and licensing costs than a Computation Fluid Dynamics (CFD) analysis while capturing the majority of the thermodynamics and heat transfer.
Modeling Xenon Tank Pressurization using One-Dimensional Thermodynamic and Heat Transfer Equations
Gilligan, Ryan P.; Tomsik, Thomas M.
2017-01-01
As a first step in understanding what ground support equipment (GSE) is required to provide external cooling during the loading of 5,000 kg of xenon into 4 aluminum lined composite overwrapped pressure vessels (COPVs), a modeling analysis was performed using Microsoft Excel. The goals of the analysis were to predict xenon temperature and pressure throughout loading at the launch facility, estimate the time required to load one tank, and to get an early estimate of what provisions for cooling xenon might be needed while the tanks are being filled. The model uses the governing thermodynamic and heat transfer equations to achieve these goals. Results indicate that a single tank can be loaded in about 15 hours with reasonable external coolant requirements. The model developed in this study was successfully validated against flight and test data. The first data set is from the Dawn mission which also utilizes solar electric propulsion with xenon propellant, and the second is test data from the rapid loading of a hydrogen cylindrical COPV. The main benefit of this type of model is that the governing physical equations using bulk fluid solid temperatures can provide a quick and accurate estimate of the state of the propellant throughout loading which is much cheaper in terms of computational time and licensing costs than a Computation Fluid Dynamics (CFD) analysis while capturing the majority of the thermodynamics and heat transfer.
International Nuclear Information System (INIS)
Gomez Palacio, German Rau
1998-01-01
Ecology is no more a descriptive and self-sufficient science. Many viewpoints are needed simultaneously to give a full coverage of such complex systems: ecosystems. These viewpoints come from physics, chemistry, and nuclear physics, without a new far from equilibrium thermodynamics and without new mathematical tools such as catastrophe theory, fractal theory, cybernetics and network theory, the development of ecosystem science would never have reached the point of today. Some ideas are presented about the importance that concept such as energy, entropy, exergy information and none equilibrium have in the analysis of processes taking place in ecosystems
Crystallization: Key thermodynamic, kinetic and hydrodynamic aspects
Indian Academy of Sciences (India)
This paper attempts to do that by critically reviewing published experimental and modelling studies on establishing and enhancing state-of-the-art thermodynamic, kinetic and hydrodynamic aspects of crystallization. Efforts are made to discuss and raise points for emerging modelling tools needed for a flexible design and ...
Thermodiffusion in Multicomponent Mixtures Thermodynamic, Algebraic, and Neuro-Computing Models
Srinivasan, Seshasai
2013-01-01
Thermodiffusion in Multicomponent Mixtures presents the computational approaches that are employed in the study of thermodiffusion in various types of mixtures, namely, hydrocarbons, polymers, water-alcohol, molten metals, and so forth. We present a detailed formalism of these methods that are based on non-equilibrium thermodynamics or algebraic correlations or principles of the artificial neural network. The book will serve as single complete reference to understand the theoretical derivations of thermodiffusion models and its application to different types of multi-component mixtures. An exhaustive discussion of these is used to give a complete perspective of the principles and the key factors that govern the thermodiffusion process.
Thermodynamic aspect in using modified Boltzmann model as an acoustic probe for URu2Si2
Kwang-Hua, Chu Rainer
2018-05-01
The approximate system of equations describing ultrasonic attenuation propagating in many electrons of the heavy-fermion materials URu2Si2 under high magnetic fields were firstly derived and then calculated based on the modified Boltzmann model considering the microscopic contributions due to electronic fluids. A system of nonlinear partial differential coupled with integral equations were linearized firstly and approximately solved considering the perturbed thermodynamic equilibrium states. Our numerical data were compared with previous measurements using non-dimensional or normalized physical values. The rather good fit of our numerical calculations with experimental measurements confirms our present approach.
Riemannian geometry in thermodynamic fluctuation theory
International Nuclear Information System (INIS)
Ruppeiner, G.
1995-01-01
Although thermodynamic fluctuation theory originated from statistical mechanics, it may be put on a completely thermodynamic basis, in no essential need of any microscopic foundation. This review views the theory from the macroscopic perspective, emphasizing, in particular, notions of covariance and consistency, expressed naturally using the language of Riemannian geometry. Coupled with these concepts is an extension of the basic structure of thermodynamic fluctuation theory beyond the classical one of a subsystem in contact with an infinite uniform reservoir. Used here is a hierarchy of concentric subsystems, each of which samples only the thermodynamic state of the subsystem immediately larger than it. The result is a covariant thermodynamic fluctuation theory which is plausible beyond the standard second-order entropy expansion. It includes the conservation laws and is mathematically consistent when applied to fluctuations inside subsystems. Tests on known models show improvements. Perhaps most significantly, the covariant theory offers a qualitatively new tool for the study of fluctuation phenomena: the Riemannian thermodynamic curvature. The thermodynamic curvature gives, for any given thermodynamic state, a lower bound for the length scale where the classical thermodynamic fluctuation theory based on a uniform environment could conceivably hold. Straightforward computation near the critical point reveals that the curvature equals the correlation volume, a physically appealing finding. The combination of the interpretation of curvature with a well-known proportionality between the free energy and the inverse of the correlation volume yields a purely thermodynamic theory of the critical point. The scaled equation of state follows from the values of the critical exponents. The thermodynamic Riemannian metric may be put into the broader context of information theory
International Nuclear Information System (INIS)
Paduszyński, Kamil; Lukoshko, Elena V.; Królikowski, Marek; Domańska, Urszula
2015-01-01
Highlights: • Solubility data for 10 molecular solvents in [BMPYR][TCB] are reported. • Excess enthalpies for 7 molecular solvents in [BMPYR][TCB] are given. • Thermodynamic modelling with PC-SAFT equation of state is presented. - Abstract: This paper presents a comprehensive thermodynamic study of binary mixtures formed by 1-butyl-1-methylpyrrolidinium tetracyanoborate ionic liquid and hydrocarbons (n-heptane, benzene, toluene, ethylbenzene), thiophene and alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol and 1-dodecanol). An impact of chemical structure of molecular compounds on their solubility in the ionic liquid and excess enthalpies of mixing is discussed. Furthermore, modelling of the measured properties by using perturbed-chain statistical associating fluid theory (PC-SAFT) is presented. The theory is applied in both correlative and semi-predictive mode involving temperature-dependent binary corrections fitted to infinite dilution activity coefficients. Solubility curves and excess enthalpies are captured by the model with a reasonable accuracy, when semi-predictive strategy is adopted. Moreover, (liquid + liquid) equilibrium phase diagram in ternary system composed of the investigated ionic liquid, thiophene and n-heptane is predicted with PC-SAFT and then the calculations are confronted with available experimental data. The results indicate that the approach proposed can be perceived as an interesting tool for reproducing the thermodynamic behaviour disclosed by such complex systems as those based on ionic liquids
A constitutive rheological model for agglomerating blood derived from nonequilibrium thermodynamics
Tsimouri, Ioanna Ch.; Stephanou, Pavlos S.; Mavrantzas, Vlasis G.
2018-03-01
Red blood cells tend to aggregate in the presence of plasma proteins, forming structures known as rouleaux. Here, we derive a constitutive rheological model for human blood which accounts for the formation and dissociation of rouleaux using the generalized bracket formulation of nonequilibrium thermodynamics. Similar to the model derived by Owens and co-workers ["A non-homogeneous constitutive model for human blood. Part 1. Model derivation and steady flow," J. Fluid Mech. 617, 327-354 (2008)] through polymer network theory, each rouleau in our model is represented as a dumbbell; the corresponding structural variable is the conformation tensor of the dumbbell. The kinetics of rouleau formation and dissociation is treated as in the work of Germann et al. ["Nonequilibrium thermodynamic modeling of the structure and rheology of concentrated wormlike micellar solutions," J. Non-Newton. Fluid Mech. 196, 51-57 (2013)] by assuming a set of reversible reactions, each characterized by a forward and a reverse rate constant. The final set of evolution equations for the microstructure of each rouleau and the expression for the stress tensor turn out to be very similar to those of Owens and co-workers. However, by explicitly considering a mechanism for the formation and breakage of rouleaux, our model further provides expressions for the aggregation and disaggregation rates appearing in the final transport equations, which in the kinetic theory-based network model of Owens were absent and had to be specified separately. Despite this, the two models are found to provide similar descriptions of experimental data on the size distribution of rouleaux.
A tool box for implementing supersymmetric models
Staub, Florian; Ohl, Thorsten; Porod, Werner; Speckner, Christian
2012-10-01
We present a framework for performing a comprehensive analysis of a large class of supersymmetric models, including spectrum calculation, dark matter studies and collider phenomenology. To this end, the respective model is defined in an easy and straightforward way using the Mathematica package SARAH. SARAH then generates model files for CalcHep which can be used with micrOMEGAs as well as model files for WHIZARD and O'Mega. In addition, Fortran source code for SPheno is created which facilitates the determination of the particle spectrum using two-loop renormalization group equations and one-loop corrections to the masses. As an additional feature, the generated SPheno code can write out input files suitable for use with HiggsBounds to apply bounds coming from the Higgs searches to the model. Combining all programs provides a closed chain from model building to phenomenology. Program summary Program title: SUSY Phenomenology toolbox. Catalog identifier: AEMN_v1_0. Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMN_v1_0.html. Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland. Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html. No. of lines in distributed program, including test data, etc.: 140206. No. of bytes in distributed program, including test data, etc.: 1319681. Distribution format: tar.gz. Programming language: Autoconf, Mathematica. Computer: PC running Linux, Mac. Operating system: Linux, Mac OS. Classification: 11.6. Nature of problem: Comprehensive studies of supersymmetric models beyond the MSSM is considerably complicated by the number of different tasks that have to be accomplished, including the calculation of the mass spectrum and the implementation of the model into tools for performing collider studies, calculating the dark matter density and checking the compatibility with existing collider bounds (in particular, from the Higgs searches). Solution method: The
Söderman, Olle; Jönsson, Bengt; Olofsson, Gerd
2006-02-23
The electrostatic properties of charged surfactant micelles are investigated through titrations of fatty acid probes solubilized in the micelles. The titration process is followed by means of calorimetric measurements and by determining the pH values as a function of added base. This approach yields a complete thermodynamic description of the titration process. In particular, we find that the process is endothermic at 298 K. This is contrary to the titration of carboxylic acids in water, where DeltaH is approximately 0. To identify the main effect underlying the difference in DeltaH between titration in a micelle and water, a thermodynamic model has been developed which focuses on the transfer properties of charged and uncharged species from bulk water to the surface of a micelle and which incorporates a dielectric discontinuity at the micellar surface. The model relies on the use of the Poisson-Boltzmann equation which is solved using a finite element method. Experimental results and the model calculations imply that the dielectric discontinuity at (or near) the micellar surface plays a major role and hence must be included when analyzing the titration behavior of an acid functionality at the surface of a charged micelle.
Atomistic modeling of thermodynamic properties of Pu-Ga alloys based on the Invar mechanism
Lee, Tongsik; Taylor, Christopher D.; Lawson, A. C.; Conradson, Steven D.; Chen, Shao Ping; Caro, A.; Valone, Steven M.; Baskes, Michael I.
2014-05-01
We present an atomistic model that accounts for a range of anomalous thermodynamic properties of the fcc δ phase of Pu-Ga alloys in terms of the Invar mechanism. Two modified embedded atom method potentials are employed to represent competing electronic states in δ-Pu, each of which has an individual configuration dependence as well as distinct interactions with gallium. Using classical Monte Carlo simulations, we compute the temperature dependence of various thermodynamic properties for different dilute gallium concentrations. The model reproduces the observed effects of excessive volume reduction along with a rapid shift in thermal expansion from negative to positive values with increasing gallium concentration. It also predicts progressive stiffening upon dilute-gallium alloying, while the calculated thermal softening is nearly independent of the gallium concentration in agreement with resonant ultrasound spectroscopy measurements in the literature. Analysis of the local structure predicted by the model indicates that the distribution of the gallium atoms is not completely random in the δ phase due to the presence of short-range order associated with the Invar mechanism. This effect is consistent with the nanoscale heterogeneity in local gallium concentration which is observed in recent extended x-ray absorption fine structure spectroscopy experiments. Implications of the Invar effect for phase stability and physical interpretations of the two states are also discussed.
International Nuclear Information System (INIS)
Prieur, D.
2011-01-01
Fuel irradiation in pressurized water reactors lead to the formation of fission products and minor actinides (Np, Am, Cm) which can be transmuted in fast neutrons reactors. In this context, the aim of this work was to study the fabrication conditions of the U 1-y Am y O 2+x fuels which exhibit particular thermodynamical properties requiring an accurate monitoring of the oxygen potential during the sintering step. For this reason, a thermodynamical model was developed to assess the optimum sintering conditions for these materials. From these calculations, U 1-y Am y O 2+x (y=0.10; 0.15; 0.20; 0.30) were sintered in two range of atmosphere. In hyper-stoichiometric conditions at low temperature, porous and multiphasic compounds are obtained whereas in reducing conditions at high temperature materials are dense and monophasic. XAFS analyses were performed in order to obtain additional experimental data for the thermodynamical modeling refinement. These characterizations also showed the reduction of Am(+IV) to Am(+III) and the partial oxidation of U(+IV) to U(+V) due to a charge compensation mechanism occurring during the sintering. Finally, taking into account the high - activity of Am, self-irradiation effects were studied for two types of microstructures and two Am contents (10 and 15%). For each composition, a lattice parameter increase was observed without structural change coupled with a macroscopic swelling of the pellet diameter up to 1.2% for the dense compounds and 0.6% for the tailored porosity materials. (author) [fr
Tomar, Dheeraj S; Weber, Valéry; Pettitt, B Montgomery; Asthagiri, D
2014-04-17
The hydration thermodynamics of the amino acid X relative to the reference G (glycine) or the hydration thermodynamics of a small-molecule analog of the side chain of X is often used to model the contribution of X to protein stability and solution thermodynamics. We consider the reasons for successes and limitations of this approach by calculating and comparing the conditional excess free energy, enthalpy, and entropy of hydration of the isoleucine side chain in zwitterionic isoleucine, in extended penta-peptides, and in helical deca-peptides. Butane in gauche conformation serves as a small-molecule analog for the isoleucine side chain. Parsing the hydrophobic and hydrophilic contributions to hydration for the side chain shows that both of these aspects of hydration are context-sensitive. Furthermore, analyzing the solute-solvent interaction contribution to the conditional excess enthalpy of the side chain shows that what is nominally considered a property of the side chain includes entirely nonobvious contributions of the background. The context-sensitivity of hydrophobic and hydrophilic hydration and the conflation of background contributions with energetics attributed to the side chain limit the ability of a single scaling factor, such as the fractional solvent exposure of the group in the protein, to map the component energetic contributions of the model-compound data to their value in the protein. But ignoring the origin of cancellations in the underlying components the group-transfer model may appear to provide a reasonable estimate of the free energy for a given error tolerance.
Energy Technology Data Exchange (ETDEWEB)
Crowley, M. F.; Matthews, J.; Beckham, G.; Bomble, Y.; Hynninen, A. P.; Ciesielski, P. F.
2012-01-01
Cellulose is still a mysterious polymer in many ways: structure of microfibrils, thermodynamics of synthesis and degradation, and interactions with other plant cell wall components. Our aim is to uncover the details and mechanisms of cellulose digestion and synthesis. We report the details of the structure of cellulose 1-beta under several temperature conditions and report here the results of these studies and connections to experimental measurements and the measurement in-silico the free energy of decrystallization of several morphologies of cellulose. In spatially large modeling, we show the most recent work of mapping atomistic and coarse-grain models into tomographic images of cellulose and extreme coarse-grain modeling of interactions of large cellulase complexes with microfibrils. We discuss the difficulties of modeling cellulose and suggest future work both experimental and theoretical to increase our understanding of cellulose and our ability to use it as a raw material for fuels and materials.
Thermodynamically consistent modeling of elementary electrochemistry in lithium-ion batteries
International Nuclear Information System (INIS)
Colclasure, Andrew M.; Kee, Robert J.
2010-01-01
This paper is particularly concerned with the elementary reactions and transport processes that are responsible for Li-ion battery performance. The model generally follows the widely practiced approach developed by Newman and co-workers (e.g., Doyle et al., J. Electrochem. Soc. 140 (1993) 1526 ). However, there are significant departures, especially in modeling electrochemical charge transfer. The present approach introduces systems of microscopically reversible reactions, including both heterogeneous thermal reactions and electrochemical charge-transfer reactions. All reaction rates are evaluated in elementary form, providing a powerful alternative to a Butler-Volmer formalism for the charge-transfer reactions. The paper is particularly concerned with the influence of non-ideal thermodynamics for evaluating reversible potentials as well as charge-transfer rates. The theory and modeling approach establishes a framework for extending chemistry models to incorporate detailed reaction mechanisms that represent multiple competitive reaction pathways.
International Nuclear Information System (INIS)
Kienzler, B.
2000-01-01
The isolation capacity of a repository system for radionuclides is described by geochemical modeling. The models for interpretation of experimental findings and for long-term extrapolation of experimental results are based on thermodynamic approaches. The geochemical models include dissolution reactions of waste forms, the evolution of the geochemical milieu, interactions of radionuclides with constituents of the groundwater (brines) and the precipitation of new solid phases. Reliable thermodynamic data, understanding of radionuclide complexation in aqueous multi-electrolyte solutions at the relevant ionic strength and knowledge on the formation of pure and mixed solids and on sorption processes are urgently needed for such model calculations. (author)
Energy Technology Data Exchange (ETDEWEB)
Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Allen, Todd R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Busby, Jeremy T [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2015-09-01
Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels in Light Water Reactor (LWR) components has been linked to changes in grain boundary composition due to irradiation induced segregation (RIS). This work developed a robust RIS modeling tool to account for thermodynamics and kinetics of the atom and defect transportation under combined thermal and radiation conditions. The diffusion flux equations were based on the Perks model formulated through the linear theory of the thermodynamics of irreversible processes. Both cross and non-cross phenomenological diffusion coefficients in the flux equations were considered and correlated to tracer diffusion coefficients through Manning’s relation. The preferential atomvacancy coupling was described by the mobility model, whereas the preferential atom-interstitial coupling was described by the interstitial binding model. The composition dependence of the thermodynamic factor was modeled using the CALPHAD approach. Detailed analysis on the diffusion fluxes near and at grain boundaries of irradiated austenitic stainless steels suggested the dominant diffusion mechanism for chromium and iron is via vacancy, while that for nickel can swing from the vacancy to the interstitial dominant mechanism. The diffusion flux in the vicinity of a grain boundary was found to be greatly influenced by the composition gradient formed from the transient state, leading to the oscillatory behavior of alloy compositions in this region. This work confirms that both vacancy and interstitial diffusion, and segregation itself, have important roles in determining the microchemistry of Fe, Cr, and Ni at irradiated grain boundaries in austenitic stainless steels.
Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions
Energy Technology Data Exchange (ETDEWEB)
Kurepin, V.A.; Kulik, D.A.; Hitpold, A.; Nicolet, M
2002-03-01
In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO{sub 2} by incremental additions of O{sub 2} in H{sub 2}O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni
Paduszyński, Kamil; Lukoshko, Elena Vadimovna; Królikowski, Marek; Domańska, Urszula; Szydłowski, Jerzy
2015-01-15
This work is concerned with thermodynamic properties of binary mixtures composed of 1-butyl-1-methylpyrrolidinium dicyanamide ionic liquid (IL) and the following molecular solvents: n-heptane, benzene, toluene, ethylbenzene, thiophene, 1-butanol, 1-hexanol, and 1-octanol. This is the very first time when experimental data on liquid-liquid equilibrium (LLE) phase diagrams and excess enthalpies of mixing (H(E)) for these systems are reported. An impact of the molecular solvent structure on LLE and H(E) is discussed. Furthermore, modeling of the properties under study is presented by using perturbed-chain statistical associating fluid theory (PC-SAFT). The equation of state is used in purely predictive and semipredictive mode. The latter one involves temperature-dependent binary corrections to combining rules employed in the PC-SAFT model determined on the basis of infinite dilution activity coefficients. The results shown indicate that such an approach can serve as an interesting modern thermodynamic tool for representation of thermodynamic data for complex ILs-based systems.
Ferlemann, Paul G.
2000-01-01
A solution methodology has been developed to efficiently model multi-specie, chemically frozen, thermally perfect gas mixtures. The method relies on the ability to generate a single (composite) set of thermodynamic and transport coefficients prior to beginning a CFD solution. While not fundamentally a new concept, many applied CFD users are not aware of this capability nor have a mechanism to easily and confidently generate new coefficients. A database of individual specie property coefficients has been created for 48 species. The seven coefficient form of the thermodynamic functions is currently used rather then the ten coefficient form due to the similarity of the calculated properties, low temperature behavior and reduced CPU requirements. Sutherland laminar viscosity and thermal conductivity coefficients were computed in a consistent manner from available reference curves. A computer program has been written to provide CFD users with a convenient method to generate composite specie coefficients for any mixture. Mach 7 forebody/inlet calculations demonstrated nearly equivalent results and significant CPU time savings compared to a multi-specie solution approach. Results from high-speed combustor analysis also illustrate the ability to model inert test gas contaminants without additional computational expense.
The wet compression technology for gas turbine power plants: Thermodynamic model
International Nuclear Information System (INIS)
Bracco, Stefano; Pierfederici, Alessandro; Trucco, Angela
2007-01-01
This paper examines from a thermodynamic point of view the effects of wet compression on gas turbine power plants, particularly analysing the influence of ambient conditions on the plant performance. The results of the mathematical model, implemented in 'Matlab' software, have been compared with the simulation results presented in literature and in particular the values of the 'evaporative rate', proposed in Araimo et al. [L. Araimo, A. Torelli, Thermodynamic analysis of the wet compression process in heavy duty gas turbine compressors, in: Proceedings of the 59th ATI Annual Congress, Genova, 2004, pp. 1249-1263; L. Araimo, A. Torelli, Wet compression technology applied to heavy duty gas turbines - GT power augmentation and efficiency upgrade, in: Proceedings of the 59th ATI Annual Congress, Genova, 2004, pp. 1265-1277] by 'Gas Turbines Department' of Ansaldo Energia S.p.A., have been taken into account to validate the model. The simulator permits to investigate the effects of the fogging and wet compression techniques and estimate the power and efficiency gain of heavy duty gas turbines operating in hot and arid conditions
Naumis, Gerardo G
2012-06-01
When a liquid melt is cooled, a glass or phase transition can be obtained depending on the cooling rate. Yet, this behavior has not been clearly captured in energy-landscape models. Here, a model is provided in which two key ingredients are considered in the landscape, metastable states and their multiplicity. Metastable states are considered as in two level system models. However, their multiplicity and topology allows a phase transition in the thermodynamic limit for slow cooling, while a transition to the glass is obtained for fast cooling. By solving the corresponding master equation, the minimal speed of cooling required to produce the glass is obtained as a function of the distribution of metastable states.
Thermodynamics and phase transitions of the pinwheel-distorted Kagome lattice Heisenberg model
Khatami, Ehsan; Singh, Rajiv R. P.; Rigol, Marcos
2012-02-01
We study the Heisenberg model on the pinwheel-distorted Kagome lattice as observed in the material Rb2Cu3SnF12. Experimentally relevant thermodynamic properties at finite temperatures are computed utilizing numerical linked-cluster expansions [1]. We introduce a Lanczos-based zero-temperature numerical linked-cluster expansion and study the approach of the pinwheel distorted lattice to the uniform Kagome lattice Heisenberg model. We find strong evidence for a phase transition before the uniform limit is reached, implying that the ground state of the Kagome lattice Heisenberg model is likely not pinwheel dimerized and is stable to finite pinwheel dimerizing perturbations [2]. [4pt] [1] M. Rigol and R. R. P. Singh, Phys. Rev. Lett. 98, 207204 (2007); Phys. Rev. B 76, 184403 (2007). [0pt] [2] E. Khatami, R. R. P. Singh, M. Rigol, preprint: arXiv:1105.4147
Thermodynamic model of social influence on two-dimensional square lattice: Case for two features
Genzor, Jozef; Bužek, Vladimír; Gendiar, Andrej
2015-02-01
We propose a thermodynamic multi-state spin model in order to describe equilibrial behavior of a society. Our model is inspired by the Axelrod model used in social network studies. In the framework of the statistical mechanics language, we analyze phase transitions of our model, in which the spin interaction J is interpreted as a mutual communication among individuals forming a society. The thermal fluctuations introduce a noise T into the communication, which suppresses long-range correlations. Below a certain phase transition point Tt, large-scale clusters of the individuals, who share a specific dominant property, are formed. The measure of the cluster sizes is an order parameter after spontaneous symmetry breaking. By means of the Corner transfer matrix renormalization group algorithm, we treat our model in the thermodynamic limit and classify the phase transitions with respect to inherent degrees of freedom. Each individual is chosen to possess two independent features f = 2 and each feature can assume one of q traits (e.g. interests). Hence, each individual is described by q2 degrees of freedom. A single first-order phase transition is detected in our model if q > 2, whereas two distinct continuous phase transitions are found if q = 2 only. Evaluating the free energy, order parameters, specific heat, and the entanglement von Neumann entropy, we classify the phase transitions Tt(q) in detail. The permanent existence of the ordered phase (the large-scale cluster formation with a non-zero order parameter) is conjectured below a non-zero transition point Tt(q) ≈ 0.5 in the asymptotic regime q → ∞.
A model for the thermodynamic analysis in a batch type fluidized bed dryer
International Nuclear Information System (INIS)
Özahi, Emrah; Demir, Hacımurat
2013-01-01
An original model for thermodynamic analysis of a batch type fluidized bed dryer is proposed herein considering two separate systems comprised of drying air medium as a control volume and particles to be dried as a control mass. By means of the proposed model, energetic and exergetic analyses of a drying column of a batch type fluidized bed dryer are carried out as an original contribution to literature since there is no such like model in which the analyses are performed considering two separate systems. The energetic efficiencies evaluated by means of the proposed model using the data in literature are compared with those in literature and a good conformity is satisfied with an acceptable error margin of ±9%. A new correlation is also developed with a mean deviation of ±10% in order to evaluate the energetic efficiency for not only corn drying process but also drying processes of other particles at inlet air temperature of 50 °C. Effects of air mass flow rate, mass of particle and ambient temperature on energetic and exergetic efficiencies are analyzed and some concluding remarks are highlighted for further studies. - Highlights: • Energetic and exergetic analyses of a batch type fluidized bed dryer are developed. • An original model is proposed for thermodynamic analyses in a fluidized bed dryer. • The proposed model is compared with the data in literature with an accuracy of ±9%. • Effect of air mass flow rate is more significant than that of ambient temperature. • Effect of mass of particle is more significant than that of ambient temperature
Vinyard, David J; Zachary, Chase E; Ananyev, Gennady; Dismukes, G Charles
2013-07-01
Forty-three years ago, Kok and coworkers introduced a phenomenological model describing period-four oscillations in O2 flash yields during photosynthetic water oxidation (WOC), which had been first reported by Joliot and coworkers. The original two-parameter Kok model was subsequently extended in its level of complexity to better simulate diverse data sets, including intact cells and isolated PSII-WOCs, but at the expense of introducing physically unrealistic assumptions necessary to enable numerical solutions. To date, analytical solutions have been found only for symmetric Kok models (inefficiencies are equally probable for all intermediates, called "S-states"). However, it is widely accepted that S-state reaction steps are not identical and some are not reversible (by thermodynamic restraints) thereby causing asymmetric cycles. We have developed a mathematically more rigorous foundation that eliminates unphysical assumptions known to be in conflict with experiments and adopts a new experimental constraint on solutions. This new algorithm termed STEAMM for S-state Transition Eigenvalues of Asymmetric Markov Models enables solutions to models having fewer adjustable parameters and uses automated fitting to experimental data sets, yielding higher accuracy and precision than the classic Kok or extended Kok models. This new tool provides a general mathematical framework for analyzing damped oscillations arising from any cycle period using any appropriate Markov model, regardless of symmetry. We illustrate applications of STEAMM that better describe the intrinsic inefficiencies for photon-to-charge conversion within PSII-WOCs that are responsible for damped period-four and period-two oscillations of flash O2 yields across diverse species, while using simpler Markov models free from unrealistic assumptions. Copyright © 2013 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Hageman, Sven; Scharge, Tina; Willms, Thomas
2015-07-15
The report on the development of a thermodynamic data base for selected heavy metals covers the description of experimental methods, the thermodynamic model for chromate, the thermodynamic model for dichromate, the thermodynamic model for manganese (II), the thermodynamic model for cobalt, the thermodynamic model for nickel, the thermodynamic model for copper (I), the thermodynamic model for copper(II), the thermodynamic model for mercury (0) and mercury (I), the thermodynamic model for mercury (III), the thermodynamic model for arsenate.
Torque-coupled thermodynamic model for FoF1 -ATPase
Ai, Guangkuo; Liu, Pengfei; Ge, Hao
2017-05-01
FoF1 -ATPase is a motor protein complex that utilizes transmembrane ion flow to drive the synthesis of adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate (Pi). While many theoretical models have been proposed to account for its rotary activity, most of them focus on the Fo or F1 portions separately rather than the complex as a whole. Here, we propose a simple but new torque-coupled thermodynamic model of FoF1 -ATPase. Solving this model at steady state, we find that the monotonic variation of each portion's efficiency becomes much more robust over a wide range of parameters when the Fo and F1 portions are coupled together, as compared to cases when they are considered separately. Furthermore, the coupled model predicts the dependence of each portion's kinetic behavior on the parameters of the other. Specifically, the power and efficiency of the F1 portion are quite sensitive to the proton gradient across the membrane, while those of the Fo portion as well as the related Michaelis constants for proton concentrations respond insensitively to concentration changes in the reactants of ATP synthesis. The physiological proton gradient across the membrane in the Fo portion is also shown to be optimal for the Michaelis constants of ADP and phosphate in the F1 portion during ATP synthesis. Together, our coupled model is able to predict key dynamic and thermodynamic features of the FoF1 -ATPase in vivo semiquantitatively, and suggests that such coupling approach could be further applied to other biophysical systems.
Garrone, Edoardo; Otero Areán, Carlos
2005-10-01
This tutorial review describes the use of variable temperature infrared spectroscopy of adsorbed species (VTIR), a recent method for studying the thermodynamics of weak solid-gas interactions. Examples show how a fundamental relationship of thermodynamics (the van't Hoff equation, used long since in several fields of physical chemistry) can describe equilibrium processes at the solid-gas interface. The VTIR method is fully exploited by measuring absorbance of an IR band, temperature and pressure over a wide temperature range: an estimation of the interaction energy is, however, possible even ignoring the equilibrium pressure. Precise thermodynamic characterization of solid-gas interactions is required in several fields: on the applied side, gas sensing, separation and storage, which involve such areas as work-place security, air pollution control and the energy sector; regarding fundamental knowledge, weak solid-gas interactions are relevant to a number of fields, including hydrogen bonding, coordination chemistry and surface phenomena in a broad sense. Infrared (IR) spectroscopy of (gas) molecules adsorbed on a solid is frequently used to characterize both, the adsorbed species and the adsorbing centres at the solid surface. The potential of the technique can be greatly enhanced by obtaining IR spectra over a temperature range, and simultaneously measuring IR absorbance, temperature and equilibrium pressure. When this is done, variable temperature infrared (VTIR) spectroscopy can be used not only for a more detailed surface characterization, but also for precise studies on the thermodynamics of solid-gas interactions. Furthermore, when weak interactions are concerned, the technique shows favourable features compared to adsorption calorimetry, or to other classical methods. The potential of the VTIR method is highlighted by reviewing recently reported studies on dihydrogen, dinitrogen and carbon monoxide adsorption on zeolites. To facilitate understanding, an
WMT: The CSDMS Web Modeling Tool
Piper, M.; Hutton, E. W. H.; Overeem, I.; Syvitski, J. P.
2015-12-01
The Community Surface Dynamics Modeling System (CSDMS) has a mission to enable model use and development for research in earth surface processes. CSDMS strives to expand the use of quantitative modeling techniques, promotes best practices in coding, and advocates for the use of open-source software. To streamline and standardize access to models, CSDMS has developed the Web Modeling Tool (WMT), a RESTful web application with a client-side graphical interface and a server-side database and API that allows users to build coupled surface dynamics models in a web browser on a personal computer or a mobile device, and run them in a high-performance computing (HPC) environment. With WMT, users can: Design a model from a set of components Edit component parameters Save models to a web-accessible server Share saved models with the community Submit runs to an HPC system Download simulation results The WMT client is an Ajax application written in Java with GWT, which allows developers to employ object-oriented design principles and development tools such as Ant, Eclipse and JUnit. For deployment on the web, the GWT compiler translates Java code to optimized and obfuscated JavaScript. The WMT client is supported on Firefox, Chrome, Safari, and Internet Explorer. The WMT server, written in Python and SQLite, is a layered system, with each layer exposing a web service API: wmt-db: database of component, model, and simulation metadata and output wmt-api: configure and connect components wmt-exe: launch simulations on remote execution servers The database server provides, as JSON-encoded messages, the metadata for users to couple model components, including descriptions of component exchange items, uses and provides ports, and input parameters. Execution servers are network-accessible computational resources, ranging from HPC systems to desktop computers, containing the CSDMS software stack for running a simulation. Once a simulation completes, its output, in NetCDF, is packaged
Modelling non-equilibrium thermodynamic systems from the speed-gradient principle.
Khantuleva, Tatiana A; Shalymov, Dmitry S
2017-03-06
The application of the speed-gradient (SG) principle to the non-equilibrium distribution systems far away from thermodynamic equilibrium is investigated. The options for applying the SG principle to describe the non-equilibrium transport processes in real-world environments are discussed. Investigation of a non-equilibrium system's evolution at different scale levels via the SG principle allows for a fresh look at the thermodynamics problems associated with the behaviour of the system entropy. Generalized dynamic equations for finite and infinite number of constraints are proposed. It is shown that the stationary solution to the equations, resulting from the SG principle, entirely coincides with the locally equilibrium distribution function obtained by Zubarev. A new approach to describe time evolution of systems far from equilibrium is proposed based on application of the SG principle at the intermediate scale level of the system's internal structure. The problem of the high-rate shear flow of viscous fluid near the rigid plane plate is discussed. It is shown that the SG principle allows closed mathematical models of non-equilibrium processes to be constructed.This article is part of the themed issue 'Horizons of cybernetical physics'. © 2017 The Author(s).
International Nuclear Information System (INIS)
Lima, R.A.T. de.
1982-01-01
Within the variational method in statistical mechanics, dynamical and thermodynamical properties of anharmonic crystal are discussed, in particular the thermal behavior of the crystalline expasion, phonons spectrum, specific heat and Debye-Weller factor (which satisfctorily describes the experimental data). Through the temperature dependent Green functions framework, dynamical and thermodynamical properties associated with the spin-Peierls transition in the magnetostrictive XY model (with one-dimensional magnetic interactions but structurally three-dimensional) are also discussed. Emphasis is given to the influence of an external magnetic field (along the z-axis) on the structural order parameter, phase diagram, specific heat, magnetization, magnetic susceptibility and phonons spectrun (acoustic and optic branches). Results are extended and new ons are exhibited such as: a) a structural Lifshitz point, which separates the uniform (U), dimerized (D) and modulated (M) phases in the T-H phase diagram; b) another special point is detected for high magnetic fields; c) the D-M first-order frontier and the metastability limits are obtained; d) for high elastic constants, fixed temperature and increasing magnetic field, the unusual sequence non uniform-uniform - non uniform-uniform is possible; e) the thermal dependence of the sound velocity presents a gap at the critical temperature. The present results have provided a quite satisfactory qualitative (and partially quantitative) description of the experiments on the TTF-BDT and MEM-(TCNQ) 2 ; this fact enables us to hope that several of our predictions indeed occur in nature. (Author) [pt
ΛCDM model in f(T) gravity: reconstruction, thermodynamics and stability
Energy Technology Data Exchange (ETDEWEB)
Salako, I.G.; Kpadonou, A.V.; Houndjo, M.J.S.; Tossa, J. [Institut de Mathématiques et de Sciences Physiques (IMSP), 01 BP 613, Porto-Novo (Benin); Rodrigues, M.E., E-mail: ines.salako@imsp-uac.org, E-mail: esialg@gmail.com, E-mail: vkpadonou@gmail.com, E-mail: sthoundjo@yahoo.fr, E-mail: joel.tossa@imsp-uac.org [Faculdade de Física, Universidade Federal do Pará, 66075-110, Belém, Pará (Brazil)
2013-11-01
We investigate some cosmological features of the ΛCDM model in the framework of the generalized teleparallel theory of gravity f(T) where T denotes the torsion scalar. Its reconstruction is performed giving rise to an integration constant Q and other input parameters according to which we point out more analysis. Thereby, we show that for some values of this constant, the first and second laws of thermodynamics can be realized in the equilibrium description, for the universe with the temperature inside the horizon equal to that at the apparent horizon. Moreover, still within these suitable values of the constant, we show that the model may be stable using the de Sitter and Power-Law cosmological solutions.
FINITE TIME THERMODYNAMIC MODELING AND ANALYSIS FOR AN IRREVERSIBLE ATKINSON CYCLE
Directory of Open Access Journals (Sweden)
Yanlin Ge
2010-01-01
Full Text Available Performance of an air-standard Atkinson cycle is analyzed by using finite-time thermodynamics. The irreversible cycle model which is more close to practice is founded. In this model, the non-linear relation between the specific heats of working fluid and its temperature, the friction loss computed according to the mean velocity of the piston, the internal irreversibility described by using the compression and expansion efficiencies, and heat transfer loss are considered. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of internal irreversibility, heat transfer loss and friction loss on the cycle performance are analyzed. The results obtained in this paper may provide guidelines for the design of practical internal combustion engines.
DEFF Research Database (Denmark)
Nguyen, Tuong-Van; Elmegaard, Brian
2016-01-01
Natural gas liquefaction systems are based on refrigeration cycles – they consist of the same operations such as heat exchange, compression and expansion, but they have different layouts, components and working fluids. The design of these systems requires a preliminary simulation and evaluation...... of their performance. However, the thermodynamic models used for this purpose are characterised by different mathematical formulations, ranges of application and levels of accuracy. This may lead to inconsistent results when estimating hydrocarbon properties and assessing the efficiency of a given process. This paper......, and (iii) optimise liquefaction systems. Three case studies are considered: a cascade layout with three pure refrigerants, a single mixed-refrigerant unit, and an expander-based configuration. Significant deviations are found between all property models, and in all case studies. The main discrepancies...
Thermodynamics in an extended mean-field theory for the Bose-Hubbard model
Huegel, Dario; Pollet, Lode
2015-03-01
We derive an extended mean-field formalism to study the thermodynamical properties of the Bose-Hubbard model. The framework can be viewed as the zero-frequency limit of bosonic dynamical mean-field theory (B-DMFT), but equally well as an extension of the mean-field approximation in which pair creation and annihilation of depleted particles is taken into account. The self-energy is treated variationally, minimizing the grand potential. We find that the T = 0 phase diagrams of the 3d and 2d Bose-Hubbard model are reproduced with an accuracy of 1 % with just 3 free (physical) parameters that are determined self-consistently. The superfluid to normal transition at finite temperature is reproduced well but less accurately than in B-DMFT.
Thermodynamics of the Bose-Hubbard model in a Bogoliubov +U theory
Hügel, Dario; Pollet, Lode
2015-06-01
We derive the Bogoliubov +U formalism to study the thermodynamical properties of the Bose-Hubbard model. The framework can be viewed as the zero-frequency limit of bosonic dynamical mean-field theory (B-DMFT), but equally well as an extension of the mean-field decoupling approximation in which pair creation and annihilation of depleted particles is taken into account. The self-energy on the impurity site is treated variationally, minimizing the grand potential. The theory containing just three parameters that are determined self-consistently reproduces the T =0 phase diagrams of the three-dimensional and two-dimensional Bose-Hubbard model with an accuracy of 1 % or better. The superfluid to normal transition at finite temperature is also reproduced well and only slightly less accurately than in B-DMFT.
International Nuclear Information System (INIS)
Mueller, Pablo
2004-01-01
The aim of this work was to develop a model to simulate the evolution of the thermodynamic variables in a nuclear reactor containment with pressure suppression pool under accidental transients.We wanted a program able to give fast results, to facilitate the physical interpretation of the phenomena involved, and to make parametric studies.We did not pretend to get a precise result of a particular case.The program was made to be used as a design tool for the containment and to solve the interactions with the primary cooling system and the other security systems of the reactor, on a conceptual design context.The model consists on energy and mass balances on control volumes with liquid water, steam and a non-condensable gas like air.The dynamics of the system is shown with a base case during a loss of coolant accident.Sensibility and effects of varying some important parameters like volumes and heat and mass transfer coefficients are studied.Finally the results for the CAREM-25 reactor are compared with the codes CORAN, MELCOR 1.8.4 and CONTAIN 2.0 [es
Comparison of BrainTool to other UML modeling and model transformation tools
Nikiforova, Oksana; Gusarovs, Konstantins
2017-07-01
In the last 30 years there were numerous model generated software systems offered targeting problems with the development productivity and the resulting software quality. CASE tools developed due today's date are being advertised as having "complete code-generation capabilities". Nowadays the Object Management Group (OMG) is calling similar arguments in regards to the Unified Modeling Language (UML) models at different levels of abstraction. It is being said that software development automation using CASE tools enables significant level of automation. Actual today's CASE tools are usually offering a combination of several features starting with a model editor and a model repository for a traditional ones and ending with code generator (that could be using a scripting or domain-specific (DSL) language), transformation tool to produce the new artifacts from the manually created and transformation definition editor to define new transformations for the most advanced ones. Present paper contains the results of CASE tool (mainly UML editors) comparison against the level of the automation they are offering.
Kou, Jisheng
2016-11-25
A general diffuse interface model with a realistic equation of state (e.g. Peng-Robinson equation of state) is proposed to describe the multi-component two-phase fluid flow based on the principles of the NVT-based framework which is a latest alternative over the NPT-based framework to model the realistic fluids. The proposed model uses the Helmholtz free energy rather than Gibbs free energy in the NPT-based framework. Different from the classical routines, we combine the first law of thermodynamics and related thermodynamical relations to derive the entropy balance equation, and then we derive a transport equation of the Helmholtz free energy density. Furthermore, by using the second law of thermodynamics, we derive a set of unified equations for both interfaces and bulk phases that can describe the partial miscibility of two fluids. A relation between the pressure gradient and chemical potential gradients is established, and this relation leads to a new formulation of the momentum balance equation, which demonstrates that chemical potential gradients become the primary driving force of fluid motion. Moreover, we prove that the proposed model satisfies the total (free) energy dissipation with time. For numerical simulation of the proposed model, the key difficulties result from the strong nonlinearity of Helmholtz free energy density and tight coupling relations between molar densities and velocity. To resolve these problems, we propose a novel convex-concave splitting of Helmholtz free energy density and deal well with the coupling relations between molar densities and velocity through very careful physical observations with a mathematical rigor. We prove that the proposed numerical scheme can preserve the discrete (free) energy dissipation. Numerical tests are carried out to verify the effectiveness of the proposed method.
New tools for generation IV assemblies modelling
International Nuclear Information System (INIS)
Sylvie Aniel-Buchheit; Edwige Richebois
2005-01-01
Full text of publication follows: In the framework of the development of generation IV concepts, the need of new assembly modelling tools arises. These concepts present more geometrical and spectral heterogeneities (radially and axially). Moreover thermal-hydraulics and neutronics aspects are so closely related that coupled computations are necessary. That raises the need for more precise and flexible tools presenting 3D features. The 3D-coupling of the thermal-hydraulic code FLICA4 with the Monte-Carlo neutronics code TRIPOLI4 was developed in that frame. This new tool enables for the first time to obtain realistic axial and radial power profiles with real feedback effects in an assembly where thermal-hydraulics and neutronics effects are closely related. The BWR is the existing concept presenting the closest heterogeneous characteristics to the various new proposed concepts. This assembly design is thus chosen to compare this new tool, presenting real 3D characteristics, to the existing ones. For design studies, the evaluation of the assembly behavior, currently necessitate a depletion scheme using a 3D thermal-hydraulics assembly calculation coupled with a 1D axial neutronics deterministic calculation (or an axial power profile chosen as a function of the assembly averaged burn-up). The 3D neutronics code (CRONOS2) uses neutronic data built by 2D deterministic assembly calculations without feedback. These cross section libraries enable to take feedbacks into account via parameters such as fuel temperature, moderator density and temperature (history parameters such as void and control rod are not useful in design evaluation). Recently, the libraries build-up has been replaced by on line multi-2D deterministic assembly calculations performed by a cell code (APOLLO2). That avoids interpolation between pre-determined parameters in the cross-section data used by the 1D axial neutronics calculation and enable to give a radial power map to the 3D thermal
Energy Technology Data Exchange (ETDEWEB)
Santana, P. [Departamento de Fisica Aplicada, Facultad de Fisica, Universidad de Santiago, E-15782 Santiago de Compostela (Spain); Mato, M.M.; Paz Andrade, C.; Carballo, E. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Vigo, E-36200 Vigo (Spain); Jimenez, E. [Departamento de Fisica, Facultade de Ciencias, Universidad de A Coruna, E-15071 A Coruna (Spain); Legido, J.L. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Vigo, E-36200 Vigo (Spain); Paz Andrade, M.I. [Departamento de Fisica Aplicada, Facultad de Fisica, Universidad de Santiago, E-15782 Santiago de Compostela (Spain)], E-mail: fapazand@usc.es
2007-10-15
The interaction parameters between group chloro (-Cl) and hydroxyl (-OH) for the group contribution model of Nitta et al. 1977 (Nitta-Chao model) have been estimated with the use of a data base of experimental thermodynamic properties. The results obtained by the Nitta-Chao model with these new parameters were compared with predictions by other models such as UNIFAC model (versions of Dang and Tassios 1986, Larsen et al. 1987 and Gmehling et al. 1993)
Ghiorso, M. S.
2014-12-01
Computational thermodynamics (CT) represents a collection of numerical techniques that are used to calculate quantitative results from thermodynamic theory. In the Earth sciences, CT is most often applied to estimate the equilibrium properties of solutions, to calculate phase equilibria from models of the thermodynamic properties of materials, and to approximate irreversible reaction pathways by modeling these as a series of local equilibrium steps. The thermodynamic models that underlie CT calculations relate the energy of a phase to temperature, pressure and composition. These relationships are not intuitive and they are seldom well constrained by experimental data; often, intuition must be applied to generate a robust model that satisfies the expectations of use. As a consequence of this situation, the models and databases the support CT applications in geochemistry and petrology are tedious to maintain as new data and observations arise. What is required to make the process more streamlined and responsive is a computational framework that permits the rapid generation of observable outcomes from the underlying data/model collections, and importantly, the ability to update and re-parameterize the constitutive models through direct manipulation of those outcomes. CT procedures that take models/data to the experiential reference frame of phase equilibria involve function minimization, gradient evaluation, the calculation of implicit lines, curves and surfaces, contour extraction, and other related geometrical measures. All these procedures are the mainstay of image processing analysis. Since the commercial escalation of video game technology, open source image processing libraries have emerged (e.g., VTK) that permit real time manipulation and analysis of images. These tools find immediate application to CT calculations of phase equilibria by permitting rapid calculation and real time feedback between model outcome and the underlying model parameters.
Thermodynamic reassessment of Nb-Ni-Ti system with order–disorder model
Energy Technology Data Exchange (ETDEWEB)
Santhy, K.; Hari Kumar, K.C.
2015-01-15
Highlights: • Thermodynamic re-assessment of Ni-Ti and Nb-Ni-Ti systems using CALPHAD with DFT. • Incorporation of order-disorder model in ternary and binaries. • Ternary solubility in the binary phases Ni{sub 3}Ti, NiTi, and NbNi{sub 3} are obtained by DFT. • Solubility of Ni{sub 3}Ti, NiTi, and NbNi{sub 3} in ternary are incorporated in modelling. • The calculated ternary Nb-Ni-Ti system compared with experimental data. - Abstract: A thermodynamic description of the Nb-Ni-Ti system is refined by combining results of first-principle total energy calculations with the CALPHAD approach. The lower order binary system Ni-Ti is reassessed with all available thermochemical and phase diagram data. Single Gibbs energy description is used for ordered and disordered bcc phase in this system. To make consistent extrapolation to ternary system, metastable B2 phase is introduced in both Nb-Ni and Nb-Ti systems. The enthalpy of formation of binary intermediate phases are calculated by first-principle method, which are compared with the experimental data. The energy of formation of hypothetical end-members in Ni-Ti binary system and the ternary solubility in the binary phases Ni{sub 3}Ti, NiTi, and NbNi{sub 3} are also calculated by first-principle method and incorporated in the modelling of those phases. Calculated phase diagram and thermochemical properties of Ni-Ti system is show good agreement with experimental data. The calculated ternary Nb-Ni-Ti system is summarily presented in the form of isothermal and isopleth sections, liquids projection and reaction scheme, with appropriate comparisons with available experimental data.
Botter, C. D.; Prada, M.; Fullea, J.
2017-12-01
The Porcupine is a North-South oriented basin located southwest of Ireland, along the North Atlantic continental margin, formed by several rifting episodes during Late Carboniferous to Early Cretaceous. The sedimentary cover is underlined by a very thin continental crust in the center of the basin (10 in the South. In spite of the abundant literature, most of the oil and gas exploration in the Porcupine Basin has been targeting its northern part and is mostly restricted to relatively shallow depths, giving a restrained overview of the basin structure. Therefore, studying the thermodynamic and composition of the deep and broader structures is needed to understand the processes linked to the formation and the symmetry signature of the basin. Here, we model the present-day thermal and compositional structure of the continental crust and lithospheric mantle underneath the Porcupine basin using gravity, seismic, heat flow and elevation data. We use an integrated geophysical-petrological framework where most relevant rock properties (density, seismic velocities) are determined as a function of temperature, pressure and composition. Our modelling approach solves simultaneously the heat transfer, thermodynamic, geopotential, seismic and isostasy equations, and fit the results to all available geophysical and petrological observables (LitMod software). In this work we have implemented a module to compute self-consistently a laterally variable lithospheric elastic thickness based on mineral physics rheological laws (yield strength envelopes over the 3D volume). An appropriate understanding of local and flexural isostatic behavior of the basin is essential to unravel its tectonic history (i.e. stretching factors, subsidence etc.). Our Porcupine basin 3D model is defined by four lithological layers, representing properties from post- and syn-rift sequences to the lithospheric mantle. The computed yield strength envelopes are representative of hyperextended lithosphere and
Set of molecular models based on quantum mechanical ab initio calculations and thermodynamic data.
Eckl, Bernhard; Vrabec, Jadran; Hasse, Hans
2008-10-09
A parametrization strategy for molecular models on the basis of force fields is proposed, which allows a rapid development of models for small molecules by using results from quantum mechanical (QM) ab initio calculations and thermodynamic data. The geometry of the molecular models is specified according to the atom positions determined by QM energy minimization. The electrostatic interactions are modeled by reducing the electron density distribution to point dipoles and point quadrupoles located in the center of mass of the molecules. Dispersive and repulsive interactions are described by Lennard-Jones sites, for which the parameters are iteratively optimized to experimental vapor-liquid equilibrium (VLE) data, i.e., vapor pressure, saturated liquid density, and enthalpy of vaporization of the considered substance. The proposed modeling strategy was applied to a sample set of ten molecules from different substance classes. New molecular models are presented for iso-butane, cyclohexane, formaldehyde, dimethyl ether, sulfur dioxide, dimethyl sulfide, thiophene, hydrogen cyanide, acetonitrile, and nitromethane. Most of the models are able to describe the experimental VLE data with deviations of a few percent.
International Nuclear Information System (INIS)
Fang Zheng; Zhang Quanru
2006-01-01
A model has been derived to predict thermodynamic properties of ternary metallic systems from those of its three binaries. In the model, the excess Gibbs free energies and the interaction parameter ω 123 for three components of a ternary are expressed as a simple sum of those of the three sub-binaries, and the mole fractions of the components of the ternary are identical with the sub-binaries. This model is greatly simplified compared with the current symmetrical and asymmetrical models. It is able to overcome some shortcomings of the current models, such as the arrangement of the components in the Gibbs triangle, the conversion of mole fractions between ternary and corresponding binaries, and some necessary processes for optimizing the various parameters of these models. Two ternary systems, Mg-Cu-Ni and Cd-Bi-Pb are recalculated to demonstrate the validity and precision of the present model. The calculated results on the Mg-Cu-Ni system are better than those in the literature. New parameters in the Margules equations expressing the excess Gibbs free energies of three binary systems of the Cd-Bi-Pb ternary system are also given
Energy Technology Data Exchange (ETDEWEB)
Venson, Giuliano Gardolinski [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Mecanica], e-mail: venson@ufmg.br; Barros, Jose Eduardo Mautone; Pereira, Josemar Figueiredo [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)], e-mail: mautone@des.cefetmg.br, e-mail: josemar_cefet@yahoo.com.br
2006-07-01
This work presents the modeling of a gas microturbine power generator. The microturbine consists in a small thermo-electrical power unit, design for combined heat and power generation. The unit has an electric generator, coaxially connected with a turbocharger, which one is driven by a fuel burner. The system also incorporates an air regenerator, used for pre-heat the combustion air, and a heat exchanger, used for water heating. The objective of the modeling is the attainment of the electrical performance and the operational limits for the microturbine in function of the subsystems operational conditions. The modeling is based on the first law of the thermodynamic, using specific models for each component. In the combustion chamber is used a model that takes the fuel injection properties, as absolute pressure and temperature. A semi-empirical model, based in the modified Euler equation, is used in the turbocharger. In the air regenerator and heat exchanger, the method of mean logarithmic temperature difference is used. Through the modeling of a commercial microturbine, reference values obtained were used in some subsystems of a new microturbine. The results for this new microturbine in development, based in automotive turbochargers, indicate a nominal electrical power of 38 kW with electrical efficiency of 33% and global efficiency of 73%. (author)
Muratore-Ginanneschi, Paolo
2013-07-01
We discuss the relevance of geometric concepts in the theory of stochastic differential equations for applications to the theory of non-equilibrium thermodynamics of small systems. In particular, we show how the Eells-Elworthy-Malliavin covariant construction of the Wiener process on a Riemann manifold provides a physically transparent formulation of optimal control problems of finite-time thermodynamic transitions. Based on this formulation, we turn to an evaluative discussion of recent results on optimal thermodynamic control and their interpretation.
Design and off-design thermodynamic model of a gas turbine for performance prediction
Energy Technology Data Exchange (ETDEWEB)
Monteiro, Ulisses A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Ensaios de Modelos de Engenharia (LEME)]. E-mail: ulisses@peno.coppe.ufrj.br; Belchior, Carlos Rodrigues Pereira [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE). Lab. de Maquinas Termicas (LMT)]. E-mail: belchior@peno.coppe.ufrj.br
2008-07-01
There are some types of faults that do not leave 'signatures' in the vibration spectrum of a gas turbine. These faults can only be detected by other analysis techniques. One of these techniques is the gas turbine performance analysis or gas path analysis which relates the efficiency, mass flow, temperature, pressure, fuel consumption and power to the gas turbine faults. In this paper the methodology used in the development of a thermodynamic model that simulates the design and off-design operation of a gas turbine with a free power turbine will be presented. The results obtained are used to predict the gas turbine performance in both design and off-design operation point, and also to simulate some types of faults. (author)
Modification of Pawlow's thermodynamical model for the melting of small single-component particles
Barybin, Anatoly; Shapovalov, Victor
2011-02-01
A new approach to the melting of small particles is proposed to modify the known Pawlow's model by taking into account the transfer of material from solid spherical particles to liquid ones through a gas phase. Thermodynamical analysis gives rise to a differential equation for the melting point Tm involving such size-dependent and temperature-dependent parameters of a material as the surface tensions σs(l ), molar heat of fusion ΔHm and molar volumes vs(l ). Solution of this equation has shown that all the limiting cases for size-independent situations coincide with results known in the literature and our analysis of size-dependent situations gives results close to the experimental data previously obtained by other authors for some metallic particles.
Collaboro: a collaborative (meta modeling tool
Directory of Open Access Journals (Sweden)
Javier Luis Cánovas Izquierdo
2016-10-01
Full Text Available Software development is becoming more and more collaborative, emphasizing the role of end-users in the development process to make sure the final product will satisfy customer needs. This is especially relevant when developing Domain-Specific Modeling Languages (DSMLs, which are modeling languages specifically designed to carry out the tasks of a particular domain. While end-users are actually the experts of the domain for which a DSML is developed, their participation in the DSML specification process is still rather limited nowadays. In this paper, we propose a more community-aware language development process by enabling the active participation of all community members (both developers and end-users from the very beginning. Our proposal, called Collaboro, is based on a DSML itself enabling the representation of change proposals during the language design and the discussion (and trace back of possible solutions, comments and decisions arisen during the collaboration. Collaboro also incorporates a metric-based recommender system to help community members to define high-quality notations for the DSMLs. We also show how Collaboro can be used at the model-level to facilitate the collaborative specification of software models. Tool support is available both as an Eclipse plug-in a web-based solution.
Performance analysis of a biogas-fueled micro gas turbine using a validated thermodynamic model
International Nuclear Information System (INIS)
Nikpey Somehsaraei, Homam; Mansouri Majoumerd, Mohammad; Breuhaus, Peter; Assadi, Mohsen
2014-01-01
This study focuses on an investigation of the fuel flexibility and performance analysis of micro gas turbines (MGTs) in biogas application. For this purpose, a steady state thermodynamic model of an MGT was developed and validated by experimental data obtained from a 100 kW MGT test rig. Quite good agreement was obtained between the measurements and the simulation results. A wide range of biogas compositions with varying methane content was simulated for this study. Necessary minor modifications to fuel valves and compressor were assumed to allow engine operation with the simulated biogas composition. The effects of biogas on the engine performance were fully analyzed at various operational conditions by changing the power demand and also the ambient temperature. Compared to the natural gas fueled case, the mass flow and pressure ratio in the MGT decreased, which resulted in a slight reduction of the surge margin. This effect became more severe, however, at low power loads and/or low ambient temperatures. For all operational conditions, the electrical efficiency decreased with decreasing methane content of the biogas. The results also indicated the negative effect of the biogas on the heat recovery in the recuperator, which lowered as the methane content of the fuel decreased. - Highlights: •The MGT performance and fuel flexibility were investigated in biogas application. •A thermodynamic model of the MGT was developed and validated with experimental data. •Changes in performance and operating conditions of components were studied. •The results showed the viability of the MGT for use in biogas application
The Use of VMD Data/Model to Test Different Thermodynamic Models for Vapour-Liquid Equilibrium
DEFF Research Database (Denmark)
Abildskov, Jens; Azquierdo-Gil, M.A.; Jonsson, Gunnar Eigil
2004-01-01
Vacuum membrane distillation (VMD) has been studied as a separation process to remove volatile organic compounds from aqueous streams. A vapour pressure difference across a microporous hydrophobic membrane is the driving force for the mass transport through the membrane pores (this transport take...... values; membrane type: PTFE/PP/PVDF; feed flow rate; feed temperature. A comparison is made between different thermodynamic models for calculating the vapour-liquid equilibrium at the membrane/pore interface. (C) 2004 Elsevier B.V. All rights reserved....
Thermodynamics and statistical physics. 2. rev. ed.
International Nuclear Information System (INIS)
Schnakenberg, J.
2002-01-01
This textbook covers tthe following topics: Thermodynamic systems and equilibrium, irreversible thermodynamics, thermodynamic potentials, stability, thermodynamic processes, ideal systems, real gases and phase transformations, magnetic systems and Landau model, low temperature thermodynamics, canonical ensembles, statistical theory, quantum statistics, fermions and bosons, kinetic theory, Bose-Einstein condensation, photon gas
Collaborative Inquiry Learning: Models, tools, and challenges
Bell, Thorsten; Urhahne, Detlef; Schanze, Sascha; Ploetzner, Rolf
2010-02-01
Collaborative inquiry learning is one of the most challenging and exciting ventures for today's schools. It aims at bringing a new and promising culture of teaching and learning into the classroom where students in groups engage in self-regulated learning activities supported by the teacher. It is expected that this way of learning fosters students' motivation and interest in science, that they learn to perform steps of inquiry similar to scientists and that they gain knowledge on scientific processes. Starting from general pedagogical reflections and science standards, the article reviews some prominent models of inquiry learning. This comparison results in a set of inquiry processes being the basis for cooperation in the scientific network NetCoIL. Inquiry learning is conceived in several ways with emphasis on different processes. For an illustration of the spectrum, some main conceptions of inquiry and their focuses are described. In the next step, the article describes exemplary computer tools and environments from within and outside the NetCoIL network that were designed to support processes of collaborative inquiry learning. These tools are analysed by describing their functionalities as well as effects on student learning known from the literature. The article closes with challenges for further developments elaborated by the NetCoIL network.
A pandemic influenza modeling and visualization tool
Energy Technology Data Exchange (ETDEWEB)
Maciejewski, Ross; Livengood, Philip; Rudolph, Stephen; Collins, Timothy F.; Ebert, David S.; Brigantic, Robert T.; Corley, Courtney D.; Muller, George A.; Sanders, Stephen W.
2011-08-01
The National Strategy for Pandemic Influenza outlines a plan for community response to a potential pandemic. In this outline, state and local communities are charged with enhancing their preparedness. In order to help public health officials better understand these charges, we have developed a modeling and visualization toolkit (PanViz) for analyzing the effect of decision measures implemented during a simulated pandemic influenza scenario. Spread vectors based on the point of origin and distance traveled over time are calculated and the factors of age distribution and population density are taken into effect. Healthcare officials are able to explore the effects of the pandemic on the population through a spatiotemporal view, moving forward and backward through time and inserting decision points at various days to determine the impact. Linked statistical displays are also shown, providing county level summaries of data in terms of the number of sick, hospitalized and dead as a result of the outbreak. Currently, this tool has been deployed in Indiana State Department of Health planning and preparedness exercises, and as an educational tool for demonstrating the impact of social distancing strategies during the recent H1N1 (swine flu) outbreak.
Multidisciplinary Modelling Tools for Power Electronic Circuits
DEFF Research Database (Denmark)
Bahman, Amir Sajjad
package, e.g. power module, DFR approach meets trade-offs in electrical, thermal and mechanical design of the device. Today, virtual prototyping of power electronic circuits using advanced simulation tools is becoming attractive due to cost/time saving in building potential designs. With simulations......This thesis presents multidisciplinary modelling techniques in a Design For Reliability (DFR) approach for power electronic circuits. With increasing penetration of renewable energy systems, the demand for reliable power conversion systems is becoming critical. Since a large part of electricity...... is processed through power electronics, highly efficient, sustainable, reliable and cost-effective power electronic devices are needed. Reliability of a product is defined as the ability to perform within its predefined functions under given conditions in a specific time. Because power electronic devices...
pycalphad: CALPHAD-based Computational Thermodynamics in Python
Directory of Open Access Journals (Sweden)
Richard Otis
2017-01-01
Full Text Available The pycalphad software package is a free and open-source Python library for designing thermodynamic models, calculating phase diagrams and investigating phase equilibria using the CALPHAD method. It provides routines for reading thermodynamic databases and solving the multi-component, multi-phase Gibbs energy minimization problem. The pycalphad software project advances the state of thermodynamic modeling by providing a flexible yet powerful interface for manipulating CALPHAD data and models. The key feature of the software is that the thermodynamic models of individual phases and their associated databases can be programmatically manipulated and overridden at run-time without modifying any internal solver or calculation code. Because the models are internally decoupled from the equilibrium solver and the models themselves are represented symbolically, pycalphad is an ideal tool for CALPHAD database development and model prototyping.
Tavakkoli, M.; Kharrat, R.; Masihi, M.; Ghazanfari, M. H.; Fadaei, S.
2012-12-01
Thermodynamic modeling is known as a promising tool for phase behavior modeling of asphaltene precipitation under different conditions such as pressure depletion and CO2 injection. In this work, a thermodynamic approach is used for modeling the phase behavior of asphaltene precipitation. The precipitated asphaltene phase is represented by an improved solid model, while the oil and gas phases are modeled with an equation of state. The PR-EOS was used to perform flash calculations. Then, the onset point and the amount of precipitated asphaltene were predicted. A computer code based on an improved solid model has been developed and used for predicting asphaltene precipitation data for one of Iranian heavy crudes, under pressure depletion and CO2 injection conditions. A significant improvement has been observed in predicting the asphaltene precipitation data under gas injection conditions. Especially for the maximum value of asphaltene precipitation and for the trend of the curve after the peak point, good agreement was observed. For gas injection conditions, comparison of the thermodynamic micellization model and the improved solid model showed that the thermodynamic micellization model cannot predict the maximum of precipitation as well as the improved solid model. The non-isothermal improved solid model has been used for predicting asphaltene precipitation data under pressure depletion conditions. The pressure depletion tests were done at different levels of temperature and pressure, and the parameters of a non-isothermal model were tuned using three onset pressures at three different temperatures for the considered crude. The results showed that the model is highly sensitive to the amount of solid molar volume along with the interaction coefficient parameter between the asphaltene component and light hydrocarbon components. Using a non-isothermal improved solid model, the asphaltene phase envelope was developed. It has been revealed that at high temperatures, an
Thermodynamic modeling of La2O3-SrO-Mn2O3-Cr2O3 for solid oxide fuel cell applications
DEFF Research Database (Denmark)
Povoden-Karadeniz, E.; Chen, Ming; Ivas, Toni
2012-01-01
The thermodynamic La–Sr–Mn–Cr–O oxide database is obtained as an extension of thermodynamic descriptions of oxide subsystems using the calculation of phase diagrams approach. Concepts of the thermodynamic modeling of solid oxide phases are discussed. Gibbs energy functions of SrCrO4, Sr2.67Cr2O8,...... thermodynamics of traditional lanthanum manganite cathode with Cr-impurities. It represents the fundament for extensions to higher orders, aiming on thermodynamic calculations in noble symmetric solid oxide fuel cells......The thermodynamic La–Sr–Mn–Cr–O oxide database is obtained as an extension of thermodynamic descriptions of oxide subsystems using the calculation of phase diagrams approach. Concepts of the thermodynamic modeling of solid oxide phases are discussed. Gibbs energy functions of SrCrO4, Sr2.67Cr2O8......, Sr2CrO4, and SrCr2O4 are presented, and thermodynamic model parameters of La–Sr–Mn–Chromite perovskite are given. Experimental solid solubilities and nonstoichiometries in La1xSrxCrO3d and LaMn1xCrxO3d are reproduced by the model. The presented oxide database can be used for applied computational...
International Nuclear Information System (INIS)
Perlovich, German L.; Ryzhakov, Alex M.; Strakhova, Nadezda N.; Kazachenko, Vladimir P.; Schaper, Klaus-Jürgen; Raevsky, Oleg A.
2014-01-01
Highlights: • Solubility processes of some sulfonamide isomers in water and 1-octanol were investigated. • Transfer processes from water to 1-octanol were evaluated by analysis of enthalpic and entropic terms. • Impact of various substituents in phenyl rings on solubility and transfer processes was studied. -- Abstract: The thermodynamic aspects of solubility processes of sulfonamides (SAs) with the general structures 4-NH 2 –C 6 H 4 –SO 2 NH–C 6 H 2 (R 1 )(R 2 )-R 3 (R 1 = 2-CH 3 , 2-Cl; R 2 = 4-CH 3 , 4-Cl; R 3 =5-H, 5-Cl), 4-NH 2 -2-Cl–C 6 H 3 –SO 2 NH–C 6 H 3 (R 1 )-R 2 (R 1 = 2-H, 2-Cl; R 2 = 4-H, 4-Cl) and 4-NH 2 -2-CH 3 –C 6 H 3 –SO 2 NH–C 6 H 3 (R 1 )-R 2 (R 1 = 2-H, 2-Cl, 2-NO 2 ; R 2 = 4-H, 4-Cl) in water and 1-octanol (as phases modeling various drug delivery pathways) were studied using the isothermal saturation method. For the sulfonamides with various substituents in phenyl rings the processes of transfer from water to 1-octanol were studied by a diagram method combined with analysis of enthalpic and entropic terms. Distinguishing between enthalpy and entropy, as is possible through the present approach, leads to the insight that the contribution of these terms is different for different molecules (entropy- or enthalpy-determined). Thus, in contrast to the interpretation of only the Gibbs energy of transfer (extensively used for pharmaceuticals in the form of the partition coefficient, logP), the analysis of thermodynamic functions of the transfer process provides additional mechanistic information. This may be important for further evaluation of the physiological distribution of drug molecules and may provide a better understanding of biopharmaceutical properties of drugs
Milosevic, M.; Hendriks, I.; Smits, R.E.R.; Schuur, Boelo; de Haan, A.B.
2013-01-01
Liquid–liquid extraction using ethers as solvents is a potentially energy saving alternative for the concentration of aqueous ferric chloride solutions. Adequate thermodynamic models that describe the behavior of the resulting quaternary systems (FeCl3, ether, acid and water) are not available in
DEFF Research Database (Denmark)
Dyekjær, Jane Dannow; Jonsdottir, Svava Osk
2003-01-01
Quantitative Structure-Property Relationship (QSPR) models for prediction of various thermodynamic properties of simple organic compounds have been developed. A number of new descriptors are proposed and used alongside with descriptors available within the Codessa program. An important feature in...
Atmospheric Model Evaluation Tool for meteorological and air quality simulations
The Atmospheric Model Evaluation Tool compares model predictions to observed data from various meteorological and air quality observation networks to help evaluate meteorological and air quality simulations.
Thermodynamic modelling of a two-stage absorption chiller driven at two-temperature levels
International Nuclear Information System (INIS)
Figueredo, Gustavo R.; Bourouis, Mahmoud; Coronas, Alberto
2008-01-01
The thermodynamic model we develop in this paper considers (i) the external irreversibilities of the endoreversible models; (ii) the irreversibilities due to heat losses; and (iii) the generation of internal entropy due to pressure drops and the temperature and concentration gradients. We considered: (i) external heat losses between the generators of high and intermediate pressures and the ambient and between the ambient and the evaporator; and (ii) internal heat losses from the generators towards the condensers and from the absorber towards the evaporator. This simple but precise model faithfully represents the trend towards efficiency variation at partial loads. We have used the model to analyse the behaviour of a water-LiBr double-stage absorption chiller with 200 kW of cooling power. This machine can operate in summer as a double-stage chiller driven by heat at 170 o C from natural gas, as a single-stage chiller driven by heat at 90 o C from solar energy, or simultaneously in combined mode at both temperatures. It can also operate in winter in 'double-lift' mode for heating with a driving heat at 170 o C from natural gas. We studied the efficiency of the machine at partial loads for several solar fractions and the distribution of the heat transfer areas between the various components of the chiller
Continuous thermodynamics for droplet vaporization: Comparison between Gamma-PDF model and QMoM
Laurent, Claire; Lavergne, Gérard; Villedieu, Philippe
2009-06-01
The Continuous Thermodynamics Model (CTM) (Cotterman et al., 1985) is a suitable method to reduce computational cost of multi-component vaporization models. The droplet composition is described by a probability density function (PDF) rather than tens of components in the classical Discrete Component Model (DCM). In the first CTM method developed for this application, the PDF was assumed to be a Γ-function (Hallett, 2000), but some problems had appeared in the case of vapor condensation at the droplet surface (Harstadt et al., 2003). The method put forward in this article, the Quadrature Method of Moments (QMoM), enables one to avoid any assumption on the PDF mathematical form. Following Lage who has developed this method for phase equilibria (Lage, 2007), this article widens the scope of QMoM to the modelling of multi-component droplet vaporization. The different CTM approaches are presented in the first part and the results obtained for a vapor condensation test case are then compared and analysed to illustrate improvements made by QMoM. To cite this article: C. Laurent et al., C. R. Mecanique 337 (2009).
Evaluation of clinical information modeling tools.
Moreno-Conde, Alberto; Austin, Tony; Moreno-Conde, Jesús; Parra-Calderón, Carlos L; Kalra, Dipak
2016-11-01
Clinical information models are formal specifications for representing the structure and semantics of the clinical content within electronic health record systems. This research aims to define, test, and validate evaluation metrics for software tools designed to support the processes associated with the definition, management, and implementation of these models. The proposed framework builds on previous research that focused on obtaining agreement on the essential requirements in this area. A set of 50 conformance criteria were defined based on the 20 functional requirements agreed by that consensus and applied to evaluate the currently available tools. Of the 11 initiative developing tools for clinical information modeling identified, 9 were evaluated according to their performance on the evaluation metrics. Results show that functionalities related to management of data types, specifications, metadata, and terminology or ontology bindings have a good level of adoption. Improvements can be made in other areas focused on information modeling and associated processes. Other criteria related to displaying semantic relationships between concepts and communication with terminology servers had low levels of adoption. The proposed evaluation metrics were successfully tested and validated against a representative sample of existing tools. The results identify the need to improve tool support for information modeling and software development processes, especially in those areas related to governance, clinician involvement, and optimizing the technical validation of testing processes. This research confirmed the potential of these evaluation metrics to support decision makers in identifying the most appropriate tool for their organization. Los Modelos de Información Clínica son especificaciones para representar la estructura y características semánticas del contenido clínico en los sistemas de Historia Clínica Electrónica. Esta investigación define, prueba y valida
A self-consistent model for thermodynamics of multicomponent solid solutions
Czech Academy of Sciences Publication Activity Database
Svoboda, Jiří; Fischer, F. D.
2016-01-01
Roč. 123, OCT (2016), s. 154-157 ISSN 1359-6462 R&D Projects: GA ČR(CZ) GA15-06390S Institutional support: RVO:68081723 Keywords : Thermodynamics * Bonding * Analytical methods Subject RIV: BJ - Thermodynamics Impact factor: 3.747, year: 2016
International Nuclear Information System (INIS)
Mansouri Majoumerd, Mohammad; Nikpey Somehsaraei, Homam; Assadi, Mohsen; Breuhaus, Peter
2014-01-01
The expected increase in distributed power generation, especially in Europe, and the necessity for a reduction in greenhouse gas emissions requires an evaluation of carbon capture application at small-scale combined heat and power plants. In this regard, a micro gas turbine (MGT), a Turbec T100, has been selected for further investigation as a baseline. A thermodynamic model validated against data obtained from a test rig has been extended to enable modeling of a CO 2 capture unit. In addition, two innovative cycles, an exhaust gas recirculation (EGR) cycle and a humid air turbine (HAT) cycle, have been investigated using the selected micro gas turbine model with a focus on improved carbon capture efficiency. The thermodynamic performance indicators of all cycles, namely, the baseline MGT cycle, the EGR cycle, and the HAT cycle, all with capture unit, are presented. The results show a considerable improvement in cycle efficiency for the HAT cycle (25.8%), compared to the baseline MGT (23.0%) and EGR (22.5%) cycles. However, the surge margin is reduced markedly for the HAT cycle. It is shown that the effect of EGR on the operation of the micro gas turbine is marginal. The effects of varying ambient air temperature on the performance of all cycles as well as the effect of different recirculation percentages on the performance of the EGR cycle have also been investigated. The results confirm that the performance in the EGR cycle is less sensitive to the change in ambient temperature, compared to the other cycles. The marginal effect of various recirculation percentages on the performance of the EGR cycle is also shown in this paper. - Highlights: • A validated MGT model based on a Turbec T100 is presented. • CO 2 capture unit is integrated to the baseline MGT model. • Micro gas turbine using EGR and HAT cycles with CO 2 capture is also investigated. • Effects of ambient temperature variation on the cycles' performance are presented. • A considerable
International Nuclear Information System (INIS)
Araoz, Joseph A.; Salomon, Marianne; Alejo, Lucio; Fransson, Torsten H.
2014-01-01
expansion and compression work; the pressure drop and heat flow through the heat exchangers; the conductive, shuttle effect and regenerator thermal losses; the temperature and mass flow distribution along the system; and the power output and efficiency of the engine. These results show that the model allows an extensive study of different parameters of the engine and thus it is suitable for design optimization studies. In addition, it also presents the capability for the integration into overall Stirling engine combined heat and power systems and therefore will allow the performance evaluation of the engine integrated on these systems. - Highlights: • A numerical thermodynamic model for Stirling engine systems was developed. • Thermodynamic equations were coupled with the heat transfer governing equations. • The model was validated with experimental and numerical data. • The brake power and engine efficiency at different conditions were calculated. • Additional model results provide a deeper insight into the engine operation
Konrad-Schmolke, M.; Schildhauer, H.
2013-12-01
Growth and chemical composition of garnet in metamorphic rocks excellently reflect thermodynamic as well kinetic properties of the host rock during garnet growth. This valuable information can be extracted from preserved compositional growth zoning patterns in garnet. However, metamorphic rocks often contain multiple garnet generations that commonly develop as corona textures with distinct compositional core-overgrowth features. This circumstance can lead to a misinterpretation of information extracted from such grains if the age- and metamorphic relations between different garnet generations are unclear. Especially garnets from high-pressure (HP) and ultra high-pressure (UHP) rocks often preserve textures that show multiple growth stages reflected in core-overgrowth differences both in main and trace element composition and in the inclusion assemblage. Distinct growth zones often have sharp boundaries with strong compositional gradients and/or inclusion- and trace-element-enriched zones. Such growth patterns indicate episodic garnet growth as well as growth interruptions during the garnet evolution. A quantitative understanding of these distinct growth pulses enables the relationship between reaction path, age determinations in spatially controlled garnet domains or temperature-time constraints to be fully characterised. In this study we apply thermodynamic forward models to simulate garnet growth along a series of HP and UHP P-T paths, representative for subducted oceanic crust. We study garnet growth in different basaltic rock compositions and under different element fractionation scenarios in order to detect path-dependent P-T regions of limited or ceased garnet growth. Modeled data along P-T trajectories involving fractional crystallisation are assembled in P-T diagrams reflecting garnet growth in a changing bulk rock composition. Our models show that in all investigated rock compositions garnet growth along most P-T trajectories is discontinuous, pulse
Kinetic model for the finite-time thermodynamics of small heat engines
Cerino, Luca; Puglisi, Andrea; Vulpiani, Angelo
2015-03-01
We study a molecular engine constituted by a gas of N ˜102 molecules enclosed between a massive piston and a thermostat. The force acting on the piston and the temperature of the thermostat are cyclically changed with a finite period τ . In the adiabatic limit τ →∞ , even for finite size N , the average work and heat reproduce the thermodynamic values, recovering the Carnot result for the efficiency. The system exhibits a stall time τ* where the net work is zero: for τ consumes work instead of producing it, acting as a refrigerator or as a heat sink. At τ >τ* the efficiency at maximum power is close to the Curzorn-Ahlborn limit. The fluctuations of work and heat display approximatively a Gaussian behavior. Based upon kinetic theory, we develop a three-variables Langevin model in which the piston's position and velocity are linearly coupled together with the internal energy of the gas. The model reproduces many of the system's features, such as the inversion of the work's sign, the efficiency at maximum power, and the approximate shape of the fluctuations. A further simplification in the model allows us to compute analytically the average work, explaining its nontrivial dependence on τ .
A thermodynamic and kinetic model for paste–aggregate interactions and the alkali–silica reaction
International Nuclear Information System (INIS)
Guthrie, George D.; Carey, J. William
2015-01-01
A new conceptual model is developed for ASR formation based on geochemical principles tied to aqueous speciation, silica solubility, kinetically controlled mineral dissolution, and diffusion. ASR development is driven largely by pH and silica gradients that establish geochemical microenvironments between paste and aggregate, with gradients the strongest within the aggregate adjacent to the paste boundary (i.e., where ASR initially forms). Super-saturation of magadiite and okenite (crystalline ASR surrogates) occurs in the zone defined by gradients in pH, dissolved silica, Na + , and Ca 2 + . This model provides a thermodynamic rather than kinetic explanation of why quartz generally behaves differently from amorphous silica: quartz solubility does not produce sufficiently high concentrations of H 4 SiO 4 to super-saturate magadiite, whereas amorphous silica does. The model also explains why pozzolans do not generate ASR: their fine-grained character precludes formation of chemical gradients. Finally, these gradients have interesting implications beyond the development of ASR, creating unique biogeochemical environments
Thermodynamically Consistent Algorithms for the Solution of Phase-Field Models
Vignal, Philippe
2016-02-11
Phase-field models are emerging as a promising strategy to simulate interfacial phenomena. Rather than tracking interfaces explicitly as done in sharp interface descriptions, these models use a diffuse order parameter to monitor interfaces implicitly. This implicit description, as well as solid physical and mathematical footings, allow phase-field models to overcome problems found by predecessors. Nonetheless, the method has significant drawbacks. The phase-field framework relies on the solution of high-order, nonlinear partial differential equations. Solving these equations entails a considerable computational cost, so finding efficient strategies to handle them is important. Also, standard discretization strategies can many times lead to incorrect solutions. This happens because, for numerical solutions to phase-field equations to be valid, physical conditions such as mass conservation and free energy monotonicity need to be guaranteed. In this work, we focus on the development of thermodynamically consistent algorithms for time integration of phase-field models. The first part of this thesis focuses on an energy-stable numerical strategy developed for the phase-field crystal equation. This model was put forward to model microstructure evolution. The algorithm developed conserves, guarantees energy stability and is second order accurate in time. The second part of the thesis presents two numerical schemes that generalize literature regarding energy-stable methods for conserved and non-conserved phase-field models. The time discretization strategies can conserve mass if needed, are energy-stable, and second order accurate in time. We also develop an adaptive time-stepping strategy, which can be applied to any second-order accurate scheme. This time-adaptive strategy relies on a backward approximation to give an accurate error estimator. The spatial discretization, in both parts, relies on a mixed finite element formulation and isogeometric analysis. The codes are
Mirani, Mohammad Reza; Rahimpour, Farshad
2015-11-27
Hydrophobic interaction chromatography (HIC) is a useful method for isolation and purification of macromolecules. HIC separates proteins on the basis of surface hydrophobicity while generally retaining the activity of proteins. Aqueous mobile phases with high salt concentrations are often used to adsorb the proteins on a mildly hydrophobic support. In this research, the thermodynamic model of Chen and Sun, which predicts the adsorption isotherms of protein in presence of different type of salts, was modified by substitution the protein and salt activities in the mobile phase instead of their concentrations. In addition, model was examined for studying the adsorption of BSA, HSA, α-lactalbumin and Trypsinogen on different sepharose gels. The model parameters of Chen and Sun are adsorption equilibrium constant (KP), protein dehydration equilibrium constant (Ks), salt coefficient (α) and number of ligand binding (n). By substitution activity instead of salt and protein concentration, two other parameters (c1 and As), which related to the activity coefficients, are added to the model. The parameters of this nonlinear model are calculated by genetic algorithm (GA). The maximum average absolute percentage deviation (AAD) for the data which are obtained from the adsorption isotherm of BSA on phenyl sepharose gel, in the presence of different concentration of NaCl was 4.8%, while for Chen and Sun model, was 22.0%. Also maximum ADD for HSA, α-lactalbumin, and Trypsinogen adsorption was 7.8, 6.9, and 8.4, respectively. The results indicate that the modified model has adequate accuracy to predict protein HIC behaviour. Copyright © 2015 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingenieria Metalurgica y de Materiales, Universidad Tecnica Federico Santa Maria, Avenida Espana 1680, Valparaiso (Chile); Guzman, D. [Departamento de Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Pontificia Universidad Catolica de Valparaiso, Av. Los Carrera 01567, Quilpue (Chile); Ordonez, Stella [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. L. Bernardo O' Higgins 3363, Santiago (Chile); Rios, R. [Instituto de Materiales y Procesos Termomecanicos, Facultad de Ciencias de la Ingenieria, Universidad Austral de Chile, General Lagos 2086, Valdivia (Chile)
2011-08-15
Highlights: {yields} Extension of solid solution in Cu-Mo systems achieved by mechanical alloying. {yields} Simple thermodynamic model to explain extension of solid solution of Mo in Cu. {yields} Model gives results that are consistent with the solubility limit extension reported in other works. - Abstract: The objective of this work is proposing a simple thermodynamic model to explain the increase in the solubility limit of the powders of the Cu-Mo systems or other binary systems processed by mechanical alloying. In the regular solution model, the effects of crystalline defects, such as; dislocations and grain boundary produced during milling were introduced. The model gives results that are consistent with the solubility limit extension reported in other works for the Cu-Cr, Cu-Nb and Cu-Fe systems processed by mechanical alloying.
A comprehensive scenario of the thermodynamic anomalies of water using the TIP4P/2005 model
Energy Technology Data Exchange (ETDEWEB)
González, Miguel A. [Departamento Química Física I, Facultad Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Department of Chemistry, Imperial College London, London SW7 2AZ (United Kingdom); Valeriani, Chantal [Departamento Química Física I, Facultad Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Departamento Física Aplicada I, Facultad Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Caupin, Frédéric [Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Abascal, José L. F. [Departamento Química Física I, Facultad Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)
2016-08-07
The striking behavior of water has deserved it to be referred to as an “anomalous” liquid. The water anomalies are greatly amplified in metastable (supercooled and/or stretched) regions. This makes difficult a complete experimental description since, beyond certain limits, the metastable phase necessarily transforms into the stable one. Theoretical interpretation of the water anomalies could then be based on simulation results of well validated water models. But the analysis of the simulations has not yet reached a consensus. In particular, one of the most popular theoretical scenarios—involving the existence of a liquid-liquid critical point (LLCP)—is disputed by several authors. In this work, we propose to use a number of exact thermodynamic relations which may shed light on this issue. Interestingly, these relations may be tested in a region of the phase diagram which is outside the LLCP thus avoiding the problems associated to the coexistence region. The central property connected to other water anomalies is the locus of temperatures at which the density along isobars attain a maximum (TMD line) or a minimum (TmD). We have performed computer simulations to evaluate the TMD and TmD for a successful water model, namely, TIP4P/2005. We have also evaluated the vapor-liquid (VL) spinodal in the region of large negative pressures. The shape of these curves and their connection to the extrema of some response functions, in particular the isothermal compressibility and heat capacity at constant pressure, provides very useful information which may help to elucidate the validity of the theoretical proposals. In this way, we are able to present for the first time a comprehensive scenario of the thermodynamic water anomalies for TIP4P/2005 and their relation to the vapor-liquid spinodal. The overall picture shows a remarkable similarity with the corresponding one for the ST2 water model, for which the existence of a LLCP has been demonstrated in recent years. It
Lee, Yi Feng; Graalfs, Heiner; Frech, Christian
2016-09-16
An extended model is developed to describe protein retention in mixed-mode chromatography based on thermodynamic principles. Special features are the incorporation of pH dependence of the ionic interaction on a mixed-mode resin and the addition of a water term into the model which enables one to describe the total number of water molecules released at the hydrophobic interfaces upon protein-ligand binding. Examples are presented on how to determine the model parameters using isocratic elution chromatography. Four mixed-mode anion-exchanger prototype resins with different surface chemistries and ligand densities were tested using isocratic elution of two monoclonal antibodies at different pH values (7-10) and encompassed a wide range of NaCl concentrations (0-5M). U-shape mixed-mode retention curves were observed for all four resins. By taking into account of the deprotonation and protonation of the weak cationic functional groups in these mixed-mode anion-exchanger prototype resins, conditions which favor protein-ligand binding via mixed-mode strong cationic ligands as well as conditions which favor protein-ligand binding via both mixed-mode strong cationic ligands and non-hydrophobic weak cationic ligands were identified. The changes in the retention curves with pH, salt, protein, and ligand can be described very well by the extended model using meaningful thermodynamic parameters like Gibbs energy, number of ionic and hydrophobic interactions, total number of released water molecules as well as modulator interaction constant. Furthermore, the fitted model parameters based on isocratic elution data can also be used to predict protein retention in dual salt-pH gradient elution chromatography. Copyright © 2016 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Leng Fei
2008-09-01
Full Text Available This paper discusses the seismic analysis of concrete dams with consideration of material nonlinearity. Based on a consistent rate-dependent model and two thermodynamics-based models, two thermodynamics-based rate-dependent constitutive models were developed with consideration of the influence of the strain rate. They can describe the dynamic behavior of concrete and be applied to nonlinear seismic analysis of concrete dams taking into account the rate sensitivity of concrete. With the two models, a nonlinear analysis of the seismic response of the Koyna Gravity Dam and the Dagangshan Arch Dam was conducted. The results were compared with those of a linear elastic model and two rate-independent thermodynamics-based constitutive models, and the influences of constitutive models and strain rate on the seismic response of concrete dams were discussed. It can be concluded from the analysis that, during seismic response, the tensile stress is the control stress in the design and seismic safety evaluation of concrete dams. In different models, the plastic strain and plastic strain rate of concrete dams show a similar distribution. When the influence of the strain rate is considered, the maximum plastic strain and plastic strain rate decrease.
International Nuclear Information System (INIS)
Wanner, H.; Wersin, P.; Sierro, N.
1992-11-01
Predictions of near field geochemistry are made using a thermodynamic model for bentonite/ground interaction. This model is a refinement and extension of the model developed by the senior author. It is based on recent experiments performed at high solid/water ratio and adapted to the Swedish type of HLW repository design. Thus, from the obtained experimental results on solution composition, the model includes chemical reactions resulting from both the impurities and the main clay fraction within the bentonite. Ion exchange reactions are treated both with and without the contribution of edge sites. Due to its thermodynamic basis, the model exhibits prediction capability over a wide range of conditions in terms of solid/water ratio. The modelling of repository conditions implies, due to the lack of experimental information, simplifications with regard to thermodynamic properties of the bentonite. This mainly involves the non-consideration of the temperature effects and of the acid/base properties of the solid. Nevertheless, our results yield insight into important processes affecting porewater chemistry. Thus, the model suggests that proton exchange reactions may exert a strong control on calcite dissolution within highly compacted bentonite. Estimations of chemical changes over time in the bentonite were done in the basis of a mixing tank model. These results indicate transformation of Na-bentonite to Ca-bentonite over time. The extent of this process, however, critically depends on the amount of carbonate present in the bentonite. (authors) (34 refs.)
Morrison, J. D.; Barley, M. H.; Murphy, F. T.; Parker, I. B.; Wheelhouse, R. W.
1995-09-01
This paper reports on the development and application of a thermodynamic model based on the second-order Modified Huron Vidal equation of state (MHV-2) to predict the properties of ternary mixtures of the refrigerants R32, R125, and R134a. The mixing rules of this equation of state have been used to incorporate directly an activity-coefficient model for the excess Gibbs free energy. The parameters for the activity-coefficient model have been derived from experimental VLE data for binary mixtures. This methodology has enabled the production of a thermodynamically consistent model which can be used to predict the phase equilibria of R32/R125/R134a mixtures. The input data used in the model are presented in the paper and the predictions of the model are compared with available experimental data. The model has been used to predict the behavior of ternary refrigerant blends of R32/R125/R134a in fractionation scenarios, such as liquid charging and vapor leakage, which are of direct interest to the refrigeration industry. Details of these applications and comparisons with experimental data are discussed, along with other general uses of the thermodynamic model.
International Nuclear Information System (INIS)
Morrison, J.D.; Barley, M.H.; Parker, I.B.
1995-01-01
This paper reports on the development and application of a thermodynamic model based on the second-order Modified Huron Vidal equation of state (MHV-2) to predict the properties of ternary mixtures of the refrigerants R32, R125, and R134a. The mixing rules of this equation of state have been used to incorporate directly an activity-coefficient model for the excess Gibbs free energy. The parameters for the activity-coefficient model have been derived from experimental VLE data for binary mixtures. This methodology has enabled the production of a thermodynamically consistent model which can be used to predict the phase equilibria of R32/R125/R134a mixtures. The input data used in the model are presented in the paper and the predictions of the model are compared with available experimental data. The model has been used to predict the behavior of ternary refrigerant blends of R32/R125/R134a in fractionation scenarios, such as liquid charging and vapor leakage, which are of direct interest to the refrigeration industry. Details of these applications and comparisons with experimental data are discussed, along with other general uses of the thermodynamic model
Thermal behaviour modelling of superplastic forming tools
Velay , Vincent; Cutard , Thierry; Guegan , N.
2008-01-01
High-temperature operational conditions of super plastic forming (SPF) tools induce very complex thermomechanical loadings responsible to their failure. Various materials can be used to manufacture forming tools: ceramic, refractory castable or heat resistant steel. In this paper, an experimental and numerical analysis is performed in order to characterise the environmental loadings undergone by the tool whatever the considered material. This investigation allows to lead a thermal calculation...
Thomas, Dennis G; Jaramillo-Riveri, Sebastian; Baxter, Douglas J; Cannon, William R
2014-12-26
We have applied a new stochastic simulation approach to predict the metabolite levels, material flux, and thermodynamic profiles of the oxidative TCA cycles found in E. coli and Synechococcus sp. PCC 7002, and in the reductive TCA cycle typical of chemolithoautotrophs and phototrophic green sulfur bacteria such as Chlorobaculum tepidum. The simulation approach is based on modeling states using statistical thermodynamics and employs an assumption similar to that used in transition state theory. The ability to evaluate the thermodynamics of metabolic pathways allows one to understand the relationship between coupling of energy and material gradients in the environment and the self-organization of stable biological systems, and it is shown that each cycle operates in the direction expected due to its environmental niche. The simulations predict changes in metabolite levels and flux in response to changes in cofactor concentrations that would be hard to predict without an elaborate model based on the law of mass action. In fact, we show that a thermodynamically unfavorable reaction can still have flux in the forward direction when it is part of a reaction network. The ability to predict metabolite levels, energy flow, and material flux should be significant for understanding the dynamics of natural systems and for understanding principles for engineering organisms for production of specialty chemicals.
Thermodynamic and kinetic modelling of the reduction of concentrated nitric acid
International Nuclear Information System (INIS)
Sicsic, David
2011-01-01
This research thesis aimed at determining and quantifying the different stages of the reduction mechanism in the case of concentrated nitric acid. After having reported the results of a bibliographical study on the chemical and electrochemical behaviour of concentrated nitric media (generalities, chemical equilibriums, NOx reactivity, electrochemical reduction of nitric acid), the author reports the development and discusses the results of a thermodynamic simulation of a nitric environment at 25 C. This allowed the main species to be identified in the liquid and gaseous phases of nitric acid solutions. The author reports an experimental electrochemical investigation coupled with analytic techniques (infrared and UV-visible spectroscopy) and shows that the reduction process depends on the cathodic overvoltage, and identifies three potential areas. A kinetic modelling of the stationary state and of the impedance is then developed in order to better determine, discuss and quantify the reduction process. The application of this kinetic model to the preliminary results of an electrochemical study performed on 304 L steel is then discussed [fr
International Nuclear Information System (INIS)
Wassilew, C.
1989-11-01
This report gives an overall evaluation of several in-reactor deformation and creep-rupture experiments performed in BR-2, FFTF, and Rapsodie on pressurised tubes of the stabilized austenitic stainless steels 1.4970, 1.4981, 1.4988, and the nickel base alloy Hastelloy-X. The irradiation induced deformation processes observed in the components operating in a neutron environment can be divided into two main groups: 1. volume conserving creep and 2. volumetric swelling. Since the observed deformation as well as damage accumulating phenomena are caused by the same constrained generated and free disposable point defects and helium atoms, it is obvious and advisable to analyze, and to model simultaneously the ensemble of the elementary mechanisms and processes effective at the same time. Phenomenological models based on the thermodynamics of irreversible processes have been developed, with the aim of: 1. grasping the partial relationships between the external variables and the response functions (creep, swelling, creep driven swelling, and time to rupture), 2. fathoming the rate-controlling mechanisms, 3. providing insight into the structural details and changes occurring during the deformation and the damage accumulating processes, 4. integrating the damage accumulating processes comprehensively, and 5. formulating the constitutive equations required to describe the elementary processes that generate plastic deformations as well as damage accumulation. (orig./MM)
Directory of Open Access Journals (Sweden)
Abdul Ghafoor Memon
2014-03-01
Full Text Available In this study, thermodynamic and statistical analyses were performed on a gas turbine system, to assess the impact of some important operating parameters like CIT (Compressor Inlet Temperature, PR (Pressure Ratio and TIT (Turbine Inlet Temperature on its performance characteristics such as net power output, energy efficiency, exergy efficiency and fuel consumption. Each performance characteristic was enunciated as a function of operating parameters, followed by a parametric study and optimization. The results showed that the performance characteristics increase with an increase in the TIT and a decrease in the CIT, except fuel consumption which behaves oppositely. The net power output and efficiencies increase with the PR up to certain initial values and then start to decrease, whereas the fuel consumption always decreases with an increase in the PR. The results of exergy analysis showed the combustion chamber as a major contributor to the exergy destruction, followed by stack gas. Subsequently, multiple regression models were developed to correlate each of the response variables (performance characteristic with the predictor variables (operating parameters. The regression model equations showed a significant statistical relationship between the predictor and response variables.
Measurement and modelling of high temperature thermodynamic properties of URh3 alloy
International Nuclear Information System (INIS)
Rai, Arun Kumar; Tripathy, Haraprasanna; Jeya Ganesh, B.; Raju, S.
2012-01-01
The high temperature phase stability of arc-melted cubic URh 3 intermetallic compound has been investigated using high temperature inverse drop calorimetry in the temperature range of 300–1273 K. URh 3 exists as a line compound with negligible solubility range. Room temperature XRD profile and elemental X-ray mapping experiments on 1273 K/3 h homogenized samples have confirmed the homogeneity and L1 2 (cF8; pm3m) crystal structure of URh 3 . The drop measurements yielded accurate values for the enthalpy increment ΔH T 0 as a function of temperature, from which the specific heat C P has been estimated. The enthalpy data obtained in this study have been compared and combined with the reported data on low temperature C P and also with the ΔH T 0 in the temperature range, 0–840 K, for a comprehensive theoretical analysis using quasiharmonic Debye–Grüneisen formalism. It is found that this model with due allowance for thermal expansion effects can successfully account for the experimentally measured thermal property data in the entire temperature region spanning 0–1273 K. Invoking a combination of measurement and modelling, a comprehensive set of thermodynamic quantities have been obtained for URh 3 .
Modeling of thermodynamic non-equilibrium flows around cylinders and in channels
Sinha, Avick; Gopalakrishnan, Shiva
2017-11-01
Numerical simulations for two different types of flash-boiling flows, namely shear flow (flow through a de-Laval nozzle) and free shear flow (flow past a cylinder) are carried out in the present study. The Homogenous Relaxation Model (HRM) is used to model the thermodynamic non-equilibrium process. It was observed that the vaporization of the fluid stream, which was initially maintained at a sub-cooled state, originates at the nozzle throat. This is because the fluid accelerates at the vena-contracta and subsequently the pressure falls below the saturation vapor pressure, generating a two-phase mixture in the diverging section of the nozzle. The mass flow rate at the nozzle was found to decrease with the increase in fluid inlet temperature. A similar phenomenon also occurs for the free shear case due to boundary layer separation, causing a drop in pressure behind the cylinder. The mass fraction of vapor is maximum at rear end of the cylinder, where the size of the wake is highest. As the back pressure is reduced, severe flashing behavior was observed. The numerical simulations were validated against available experimental data. The authors gratefully acknowledge funding from the public-private partnership between DST, Confederation of Indian Industry and General Electric Pvt. Ltd.
Thermodynamic Modeling of Ag-Ni System Combining Experiments and Molecular Dynamic Simulation
Rajkumar, V. B.; Chen, Sinn-wen
2017-04-01
Ag-Ni is a simple and important system with immiscible liquids and (Ag,Ni) phases. Previously, this system has been thermodynamically modeled utilizing certain thermochemical and phase equilibria information based on conjecture. An attempt is made in this study to determine the missing information which are difficult to measure experimentally. The boundaries of the liquid miscibility gap at high temperatures are determined using a pyrometer. The temperature of the liquid ⇌ (Ag) + (Ni) eutectic reaction is measured using differential thermal analysis. Tie-lines of the Ag-Ni system at 1023 K and 1473 K are measured using a conventional metallurgical method. The enthalpy of mixing of the liquid at 1773 K and the (Ag,Ni) at 973 K is calculated by molecular dynamics simulation using a large-scale atomic/molecular massively parallel simulator. These results along with literature information are used to model the Gibbs energy of the liquid and (Ag,Ni) by a calculation of phase diagrams approach, and the Ag-Ni phase diagram is then calculated.
Directory of Open Access Journals (Sweden)
J. R. Figueiredo
2006-12-01
Full Text Available A nonequilibrium heat and mass transfer model is presented for the steady-state operation of a rectifying column, employed in ammonia-water absorption refrigeration systems to dehumidify the ammonia vapor leaving the generator. The thermodynamic state relations of the mixture are derived from two equations representing the Gibbs free energy in terms of temperature, pressure and concentration for the liquid and the vapor phases. Two of the transport properties, surface tension and liquid diffusivity required original relations, as presented here in. The resulting nonlinear system of equations is solved by efficient use of the Newton-Raphson code that minimizes the order of the Jacobian matrix without losing any model information or the quadratic order of convergence of the numerical method. Accuracy tests are performed by grid refinement and by comparison with results in the literature. A sensitivity study is presented showing the influence of some alternative methods for estimation of the transport properties on the temperature and concentration profiles.
QCD thermodynamics from an imaginary μB: Results on the four flavor lattice model
International Nuclear Information System (INIS)
D'Elia, Massimo; Lombardo, Maria-Paola
2004-01-01
We study four flavor QCD at nonzero temperature and density by analytic continuation from an imaginary chemical potential. The explored region is T=0.95T c c , and the baryochemical potentials range from 0 to ≅500 MeV. Observables include the number density, the order parameter for chiral symmetry, and the pressure, which is calculated via an integral method at fixed temperature and quark mass. The simulations are carried out on a 16 3 x4 lattice, and the mass dependence of the results is estimated by exploiting the Maxwell relations. In the hadronic region, we confirm that the results are consistent with a simple resonance hadron gas model, and we estimate the critical density by combining the results for the number density with those for the critical line. In the hot phase, above the end point of the Roberge-Weiss transition T E ≅1.1T c , the results are consistent with a free lattice model with a fixed effective number of flavor slightly different from four. We confirm that confinement and chiral symmetry are coincident by a further analysis of the critical line, and we discuss the interrelation between thermodynamics and critical behavior. We comment on the strength and weakness of the method, and propose further developments
Urbic, Tomaz
2017-07-01
In this paper we applied analytical theories for the two dimensional chain-forming fluid. Wertheims thermodynamic perturbation theory (TPT) and integral equation theory (IET) for associative liquids were used to study thermodynamical and structural properties of the chain-forming model. The model has polymerizing points at arbitrary position from center of the particles. Calculated analytical results were tested against corresponding results obtained by Monte Carlo computer simulations to check the accuracy of the theories. The theories are accurate for the different positions of patches of the model at all values of the temperature and density studied. The IET's pair correlation functions of the model agree well with computer simulations. Both TPT and IET are in good agreement with the Monte Carlo values of the energy, chemical potential and ratios of free, once and twice bonded particles.
Nakano, Tadashi; Moore, Michael
2017-01-01
(Preliminary) The book presents the state of art in the emerging field of molecular and nanoscale communication. It gives special attention to fundamental models, and advanced methodologies and tools used in the field. It covers a wide range of applications, e.g. nanomedicine, nanorobot communication, bioremediation and environmental managements. It addresses advanced graduate students, academics and professionals working at the forefront in their fields and at the interfaces between different areas of research, such as engineering, computer science, biology and nanotechnology.
Directory of Open Access Journals (Sweden)
Ruberlan Gomes da Silva
2017-01-01
Full Text Available Chemical fertilizers, such as potassium chloride, ammonium nitrate and other chemical products like sodium hydroxide and soda ash are produced from electrolyte solutions or brines with a high content of soluble salts. Some of these products are manufactured by fractional crystallization, when several salts are separated as solid phases with high purity (>90%. Due to the large global demand for potassium fertilizers, a good knowledge about the compositions of salts and brines is helpful to design an effective process. A thermodynamic model based on Pitzer and Harvie's model was used to predict the composition of crystallized salts after water removal by forced evaporation and cooling from multicomponent solutions or brines. Initially, the salts’ solubilities in binary systems (NaCl–H2O, KCl–H2O and MgCl2–H2O and ternary system (KCl–MgCl2–H2O were calculated at 20 °C and compared with literature data. Next, the model was compared to our experimental data on the quinary system NaCl–KCl–MgCl2–CaCl2–H2O system at 20 °C. The Pitzer and Harvie's model represented well both the binary and ternary systems. Besides, for the quinary system the fit was good for brine densities up to 1350 kg/m3. The models were used to estimate the chemical composition of the solutions and salts produced by fractional crystallization and in association with material balance to respond to issues related to the production rates in a solar pond containing several salts dissolved, for instance, NaCl, KCl, MgCl2 and CaCl2.
Chapman, Brian
2017-06-01
This paper seeks to develop a more thermodynamically sound pedagogy for students of biological transport than is currently available from either of the competing schools of linear non-equilibrium thermodynamics (LNET) or Michaelis-Menten kinetics (MMK). To this end, a minimal model of facilitated diffusion was constructed comprising four reversible steps: cis- substrate binding, cis → trans bound enzyme shuttling, trans -substrate dissociation and trans → cis free enzyme shuttling. All model parameters were subject to the second law constraint of the probability isotherm, which determined the unidirectional and net rates for each step and for the overall reaction through the law of mass action. Rapid equilibration scenarios require sensitive 'tuning' of the thermodynamic binding parameters to the equilibrium substrate concentration. All non-equilibrium scenarios show sigmoidal force-flux relations, with only a minority of cases having their quasi -linear portions close to equilibrium. Few cases fulfil the expectations of MMK relating reaction rates to enzyme saturation. This new approach illuminates and extends the concept of rate-limiting steps by focusing on the free energy dissipation associated with each reaction step and thereby deducing its respective relative chemical impedance. The crucial importance of an enzyme's being thermodynamically 'tuned' to its particular task, dependent on the cis- and trans- substrate concentrations with which it deals, is consistent with the occurrence of numerous isoforms for enzymes that transport a given substrate in physiologically different circumstances. This approach to kinetic modelling, being aligned with neither MMK nor LNET, is best described as intuitive non-equilibrium thermodynamics, and is recommended as a useful adjunct to the design and interpretation of experiments in biotransport.
International Nuclear Information System (INIS)
Dalmolin, Irede; Rigo, Aline A.; Corazza, Marcos L.; Ndiaye, Papa M.; Meireles, M. Angela A.; Batista, Eduardo A.C.; Oliveira, J. Vladimir
2014-01-01
This short communication reports phase equilibrium data (cloud points), employing the synthetic static method, for the system {grape seed oil (GSO) + carbon dioxide (CO 2 ) + ethanol} up to T = 343.15 K and 22.53 MPa. Experimental results were modelled using the Peng-Robinson equation of state with the classical van der Waals quadratic mixing rule (PR-vdW2). It is shown that the thermodynamic model is able to represent satisfactorily the phase behaviour of the system investigated
Developing a Modeling Tool Using Eclipse
Kirtley, Nick; Waqas Kamal, Ahmad; Avgeriou, Paris
2008-01-01
Tool development using an open source platform provides autonomy to users to change, use, and develop cost-effective software with freedom from licensing requirements. However, open source tool development poses a number of challenges, such as poor documentation and continuous evolution. In this
Czech Academy of Sciences Publication Activity Database
Bakardjieva, Snejana; Barrachin, M.; Bechta, S.; Bezdička, Petr; Bottomley, D.; Brissoneau, L.; Cheynet, B.; Dugne, O.; Fischer, E.; Fischer, M.; Gusarov, V.; Journeau, C.; Khabensky, V.; Kiselová, M.; Manara, D.; Piluso, P.; Sheindlin, M.; Tyrpekl, V.; Wiss, T.
2014-01-01
Roč. 74, SI (2014), s. 110-124 ISSN 0306-4549 Institutional support: RVO:61388980 Keywords : Corium * Severe accidents * Thermodynamic database Subject RIV: CA - Inorganic Chemistry Impact factor: 0.960, year: 2014
Thermodynamic modelling of phase equilibria in Al–Ga–P–As system
Indian Academy of Sciences (India)
Unknown
- perimental ... In the present investigation, therefore, a multiparameter function is adopted for interpretation of thermodynamic behaviour of the liquid alloys in the system. According ...... temperature than those derived based on the simple solu-.
Simulation Tools Model Icing for Aircraft Design
2012-01-01
the years from strictly a research tool to one used routinely by industry and other government agencies. Glenn contractor William Wright has been the architect of this development, supported by a team of researchers investigating icing physics, creating validation data, and ensuring development according to standard software engineering practices. The program provides a virtual simulation environment for determining where water droplets strike an airfoil in flight, what kind of ice would result, and what shape that ice would take. Users can enter geometries for specific, two-dimensional cross sections of an airfoil or other airframe surface and then apply a range of inputs - different droplet sizes, temperatures, airspeeds, and more - to model how ice would build up on the surface in various conditions. The program s versatility, ease of use, and speed - LEWICE can run through complex icing simulations in only a few minutes - have contributed to it becoming a popular resource in the aviation industry.
Implicit constitutive models with a thermodynamic basis: a study of stress concentration
Bridges, C.; Rajagopal, K. R.
2015-02-01
Motivated by the recent generalization of the class of elastic bodies by Rajagopal (Appl Math 48:279-319, 2003), there have been several recent studies that have been carried out within the context of this new class. Rajagopal and Srinivasa (Proc R Soc Ser A 463:357-367, 2007, Proc R Soc Ser A: Math Phys Eng Sci 465:493-500, 2009) provided a thermodynamic basis for such models and appealing to the idea that rate of entropy production ought to be maximized they developed nonlinear rate equations of the form where T is the Cauchy stress and D is the stretching tensor as well as , where S is the Piola-Kirchhoff stress tensor and E is the Green-St. Venant strain tensor. We follow a similar procedure by utilizing the Gibb's potential and the left stretch tensor V from the Polar Decomposition of the deformation gradient, and we show that when the displacement gradient is small one arrives at constitutive relations of the form . This is, of course, in stark contrast to traditional elasticity wherein one obtains a single model, Hooke's law, when the displacement gradient is small. By solving a classical boundary value problem, with a particular form for f( T), we show that when the stresses are small, the strains are also small which is in agreement with traditional elasticity. However, within the context of our model, when the stress blows up the strains remain small, unlike the implications of Hooke's law. We use this model to study boundary value problems in annular domains to illustrate its efficacy.
Thermodynamic model of a thermal storage air conditioning system with dynamic behavior
Energy Technology Data Exchange (ETDEWEB)
Fleming, E; Wen, SY; Shi, L; da Silva, AK
2013-12-01
A thermodynamic model was developed to predict transient behavior of a thermal storage system, using phase change materials (PCMs), for a novel electric vehicle climate conditioning application. The main objectives of the paper are to consider the system's dynamic behavior, such as a dynamic air flow rate into the vehicle's cabin, and to characterize the transient heat transfer process between the thermal storage unit and the vehicle's cabin, while still maintaining accurate solution to the complex phase change heat transfer. The system studied consists of a heat transfer fluid circulating between either of the on-board hot and cold thermal storage units, which we refer to as thermal batteries, and a liquid-air heat exchanger that provides heat exchange with the incoming air to the vehicle cabin. Each thermal battery is a shell-and-tube configuration where a heat transfer fluid flows through parallel tubes, which are surrounded by PCM within a larger shell. The system model incorporates computationally inexpensive semianalytic solution to the conjugated laminar forced convection and phase change problem within the battery and accounts for airside heat exchange using the Number of Transfer Units (NTUs) method for the liquid-air heat exchanger. Using this approach, we are able to obtain an accurate solution to the complex heat transfer problem within the battery while also incorporating the impact of the airside heat transfer on the overall system performance. The implemented model was benchmarked against a numerical study for a melting process and against full system experimental data for solidification using paraffin wax as the PCM. Through modeling, we demonstrate the importance of capturing the airside heat exchange impact on system performance, and we investigate system response to dynamic operating conditions, e.g., air recirculation. (C) 2013 Elsevier Ltd. All rights reserved.
Donnet, Marcel; Bowen, Paul; Lemaître, Jacques
2009-01-01
Thermodynamic solubility calculations are normally only related to thermodynamic equilibria in solution. In this paper, we extend the use of such solubility calculations to help elucidate possible precipitation reaction pathways during the entire reaction. We also estimate the interfacial energy of particles using only solubility data by a modification of Mersmann’s approach. We have carried this out by considering precipitation reactions as a succession of small quasi-equilibrium states. Thu...
Haack, Lukas; Peniche, Ricardo; Sommer, Lutz; Kather, Alfons
2017-06-01
At early project stages, the main CSP plant design parameters such as turbine capacity, solar field size, and thermal storage capacity are varied during the techno-economic optimization to determine most suitable plant configurations. In general, a typical meteorological year with at least hourly time resolution is used to analyze each plant configuration. Different software tools are available to simulate the annual energy yield. Software tools offering a thermodynamic modeling approach of the power block and the CSP thermal cycle, such as EBSILONProfessional®, allow a flexible definition of plant topologies. In EBSILON, the thermodynamic equilibrium for each time step is calculated iteratively (quasi steady state), which requires approximately 45 minutes to process one year with hourly time resolution. For better presentation of gradients, 10 min time resolution is recommended, which increases processing time by a factor of 5. Therefore, analyzing a large number of plant sensitivities, as required during the techno-economic optimization procedure, the detailed thermodynamic simulation approach becomes impracticable. Suntrace has developed an in-house CSP-Simulation tool (CSPsim), based on EBSILON and applying predictive models, to approximate the CSP plant performance for central receiver and parabolic trough technology. CSPsim significantly increases the speed of energy yield calculations by factor ≥ 35 and has automated the simulation run of all predefined design configurations in sequential order during the optimization procedure. To develop the predictive models, multiple linear regression techniques and Design of Experiment methods are applied. The annual energy yield and derived LCOE calculated by the predictive model deviates less than ±1.5 % from the thermodynamic simulation in EBSILON and effectively identifies the optimal range of main design parameters for further, more specific analysis.
Ito, Sosuke
2016-01-01
The transfer entropy is a well-established measure of information flow, which quantifies directed influence between two stochastic time series and has been shown to be useful in a variety fields of science. Here we introduce the transfer entropy of the backward time series called the backward transfer entropy, and show that the backward transfer entropy quantifies how far it is from dynamics to a hidden Markov model. Furthermore, we discuss physical interpretations of the backward transfer entropy in completely different settings of thermodynamics for information processing and the gambling with side information. In both settings of thermodynamics and the gambling, the backward transfer entropy characterizes a possible loss of some benefit, where the conventional transfer entropy characterizes a possible benefit. Our result implies the deep connection between thermodynamics and the gambling in the presence of information flow, and that the backward transfer entropy would be useful as a novel measure of information flow in nonequilibrium thermodynamics, biochemical sciences, economics and statistics. PMID:27833120
Energy Technology Data Exchange (ETDEWEB)
Xu, Wen-Sheng, E-mail: wsxu@uchicago.edu [James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Freed, Karl F., E-mail: freed@uchicago.edu [James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Department of Chemistry, The University of Chicago, Chicago, Illinois 60637 (United States)
2015-07-14
The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in Paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction ϕ or temperature T is high, but opposes self-assembly when both ϕ and T are sufficiently low. This allows us to identify a boundary line in the ϕ-T plane that separates two regions of qualitatively different influence of chain stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts.
Thermodynamics of a solvable quark model inspired by the Gribov-Zwanziger theory
International Nuclear Information System (INIS)
Mintz, B.W.; Guimaraes, M.S.
2013-01-01
Full text: In an attempt to solve the problem of spurious gauge copies in the path integral approach to gauge theories, V. N. Gribov proposed in 1978 a method to restrict the integration domain of the path integral to only one gauge field representative of each physical field configuration. As a result, the quadratic part of the gluon propagator is modified in the infrared, so that it acquires complex poles, i.e., complex m asses . This implies the absence of gluons in the physical spectrum, which is a necessary condition for confinement. An analogous reasoning may be applied to quark fields coupled to the gauge fields. As a consequence, the quark propagator also gets modified in the infrared, giving rise to unphysical propagators (i.e., with complex poles) at small momenta. Such a property is understood as a sign of both quark confinement and of the breaking of chiral symmetry in the vacuum. In this work, we study the thermodynamics of this model by exactly calculating the partition function using standard methods of finite-temperature quantum field theory. We find that the infrared behavior of the quark propagator leads to a highly nontrivial pressure as a function of the temperature, which is qualitatively close to the results from lattice QCD at finite temperature. (author)
Properties of Reduced Carbon Dioxide Fluid: Evidence from Experimental and Thermodynamic Modeling
Simakin, A. G.; Devyatova, V. N.; Salova, T. P.; Zelensky, M. E.
2018-01-01
It is shown experimentally that fluid mostly consisting of CO2 and CO is a good solvent for many petrogenic and ore components under high P-T parameters. Siderite decomposed to oxides and a mixture of CO2 and CO was the source of the fluid in the experiment. It is demonstrated that an ultrapotassic alkaline melt was formed on the oxide matrix as a result of fluid transport of the components of the basaltic melt at 2-5 kbar and 900-1000°C. This melt is characterized by high concentrations of Rb, LREE, Sr, and Ba. The mechanism of solubility of metals in the carbon dioxide-reduced fluid includes the formation of volatile carbonyls. As is evident from thermodynamic modeling, the stability of Ni(CO)4 at high pressure reaches magmatic temperatures. The finding of native nickel in aerosols during eruption of the Tolbachik Volcano in 2012-2013 is explained by decomposition of carbonyl from fluid of a deep origin during magma ascent.
International Nuclear Information System (INIS)
Malmberg, T.
1993-09-01
The objective of this study is to derive and investigate thermodynamic restrictions for a particular class of internal variable models. Their evolution equations consist of two contributions: the usual irreversible part, depending only on the present state, and a reversible but path dependent part, linear in the rates of the external variables (evolution equations of ''mixed type''). In the first instance the thermodynamic analysis is based on the classical Clausius-Duhem entropy inequality and the Coleman-Noll argument. The analysis is restricted to infinitesimal strains and rotations. The results are specialized and transferred to a general class of elastic-viscoplastic material models. Subsequently, they are applied to several viscoplastic models of ''mixed type'', proposed or discussed in the literature (Robinson et al., Krempl et al., Freed et al.), and it is shown that some of these models are thermodynamically inconsistent. The study is closed with the evaluation of the extended Clausius-Duhem entropy inequality (concept of Mueller) where the entropy flux is governed by an assumed constitutive equation in its own right; also the constraining balance equations are explicitly accounted for by the method of Lagrange multipliers (Liu's approach). This analysis is done for a viscoplastic material model with evolution equations of the ''mixed type''. It is shown that this approach is much more involved than the evaluation of the classical Clausius-Duhem entropy inequality with the Coleman-Noll argument. (orig.) [de
Energy Technology Data Exchange (ETDEWEB)
M.S. Gruszkiewiez; D.A. Palmer; R.D. Springer; P. Wang; A. Anderko
2006-09-14
A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems.
Müller, Ingo
1993-01-01
Physicists firmly believe that the differential equations of nature should be hyperbolic so as to exclude action at a distance; yet the equations of irreversible thermodynamics - those of Navier-Stokes and Fourier - are parabolic. This incompatibility between the expectation of physicists and the classical laws of thermodynamics has prompted the formulation of extended thermodynamics. After describing the motifs and early evolution of this new branch of irreversible thermodynamics, the authors apply the theory to mon-atomic gases, mixtures of gases, relativistic gases, and "gases" of phonons and photons. The discussion brings into perspective the various phenomena called second sound, such as heat propagation, propagation of shear stress and concentration, and the second sound in liquid helium. The formal mathematical structure of extended thermodynamics is exposed and the theory is shown to be fully compatible with the kinetic theory of gases. The study closes with the testing of extended thermodynamics thro...
Fort, Jérôme; Porter, Warren P; Grémillet, David
2009-08-01
Studying the energetics of marine top predators such as seabirds is essential to understand processes underlying adult winter survival and its impact on population dynamics. Winter survival is believed to be the single most important life-history trait in long-lived species but its determinants are largely unknown. Seabirds are inaccessible during this season, so conventional metabolic studies are extremely challenging and new approaches are needed. This paper describes and uses a state-of-the-art mechanistic model, Niche Mapper, to predict energy expenditure and food requirements of the two main seabird species wintering in the northwest Atlantic. We found that energy demand increased throughout the winter phase in both species. Across this period, mean estimated daily energy requirements were 1306 kJ day(-1) for Brünnich's guillemots (Uria lomvia) and 430 kJ day(-1) for little auks (Alle alle) wintering off Greenland and Newfoundland. Mean estimated daily food requirements were 547 g wet food day(-1) for Brünnich's guillemots, and 289 g wet food day(-1) for little auks. For both species and both wintering sites, our model predicts a sharp increase in energy expenditure between November and December, primarily driven by climatic factors such as air temperature and wind speed. These findings strongly suggest the existence of an energetic bottleneck for North Atlantic seabirds towards the end of the year, a challenging energetic phase which might explain recurrent events of winter mass-mortality, so called 'seabird winter wrecks'. Our study therefore emphasizes the relevance of thermodynamics/biophysical modelling for investigating the energy balance of wintering marine top predators and its interplay with survival and population dynamics in the context of global change.
Modeling finite-volume effects and chiral symmetry breaking in two-flavor QCD thermodynamics
Klein, Bertram
2017-11-01
Finite-volume effects in Quantum Chromodynamics (QCD) have been a subject of much theoretical interest for more than two decades. They are in particular important for the analysis and interpretation of QCD simulations on a finite, discrete space-time lattice. Most of these effects are closely related to the phenomenon of spontaneous breaking of the chiral flavor symmetry and the emergence of pions as light Goldstone bosons. These long-range fluctuations are strongly affected by putting the system into a finite box, and an analysis with different methods can be organized according to the interplay between pion mass and box size. The finite volume also affects critical behavior at the chiral phase transition in QCD. In the present review, I will be mainly concerned with modeling such finite volume effects as they affect the thermodynamics of the chiral phase transition for two quark flavors. I review recent work on the analysis of finite-volume effects which makes use of the quark-meson model for dynamical chiral symmetry breaking. To account for the effects of critical long-range fluctuations close to the phase transition, most of the calculations have been performed using non-perturbative Renormalization Group (RG) methods. I give an overview over the application of these methods to a finite volume. The method, the model and the results are put into the context of related work in random matrix theory for very small volumes, chiral perturbation theory for larger volumes, and related methods and approaches. They are applied towards the analysis of finite-volume effects in lattice QCD simulations and their interpretation, mainly in the context of the chiral phase transition for two quark flavors.
Dynamic wind turbine models in power system simulation tool
DEFF Research Database (Denmark)
Hansen, A.; Jauch, Clemens; Soerensen, P.
The present report describes the dynamic wind turbine models implemented in the power system simulation tool DIgSILENT. The developed models are a part of the results of a national research project, whose overall objective is to create a model database in different simulation tools. The report...
Thermodynamic model of a thermal storage air conditioning system with dynamic behavior
International Nuclear Information System (INIS)
Fleming, Evan; Wen, Shaoyi; Shi, Li; Silva, Alexandre K. da
2013-01-01
Highlights: • We developed an automotive thermal storage air conditioning system model. • The thermal storage unit utilizes phase change materials. • We use semi-analytic solution to the coupled phase change and forced convection. • We model the airside heat exchange using the NTU method. • The system model can incorporate dynamic inputs, e.g. variable inlet airflow. - Abstract: A thermodynamic model was developed to predict transient behavior of a thermal storage system, using phase change materials (PCMs), for a novel electric vehicle climate conditioning application. The main objectives of the paper are to consider the system’s dynamic behavior, such as a dynamic air flow rate into the vehicle’s cabin, and to characterize the transient heat transfer process between the thermal storage unit and the vehicle’s cabin, while still maintaining accurate solution to the complex phase change heat transfer. The system studied consists of a heat transfer fluid circulating between either of the on-board hot and cold thermal storage units, which we refer to as thermal batteries, and a liquid–air heat exchanger that provides heat exchange with the incoming air to the vehicle cabin. Each thermal battery is a shell-and-tube configuration where a heat transfer fluid flows through parallel tubes, which are surrounded by PCM within a larger shell. The system model incorporates computationally inexpensive semi-analytic solution to the conjugated laminar forced convection and phase change problem within the battery and accounts for airside heat exchange using the Number of Transfer Units (NTUs) method for the liquid–air heat exchanger. Using this approach, we are able to obtain an accurate solution to the complex heat transfer problem within the battery while also incorporating the impact of the airside heat transfer on the overall system performance. The implemented model was benchmarked against a numerical study for a melting process and against full system
Modeling and Simulation Tools for Heavy Lift Airships
Hochstetler, Ron; Chachad, Girish; Hardy, Gordon; Blanken, Matthew; Melton, John
2016-01-01
For conventional fixed wing and rotary wing aircraft a variety of modeling and simulation tools have been developed to provide designers the means to thoroughly investigate proposed designs and operational concepts. However, lighter-than-air (LTA) airships, hybrid air vehicles, and aerostats have some important aspects that are different from heavier-than-air (HTA) vehicles. In order to account for these differences, modifications are required to the standard design tools to fully characterize the LTA vehicle design and performance parameters.. To address these LTA design and operational factors, LTA development organizations have created unique proprietary modeling tools, often at their own expense. An expansion of this limited LTA tool set could be accomplished by leveraging existing modeling and simulation capabilities available in the National laboratories and public research centers. Development of an expanded set of publicly available LTA modeling and simulation tools for LTA developers would mitigate the reliance on proprietary LTA design tools in use today. A set of well researched, open source, high fidelity LTA design modeling and simulation tools would advance LTA vehicle development and also provide the analytical basis for accurate LTA operational cost assessments. This paper will present the modeling and analysis tool capabilities required for LTA vehicle design, analysis of operations, and full life-cycle support. A survey of the tools currently available will be assessed to identify the gaps between their capabilities and the LTA industry's needs. Options for development of new modeling and analysis capabilities to supplement contemporary tools will also be presented.
Modeling and Tool Wear in Routing of CFRP
International Nuclear Information System (INIS)
Iliescu, D.; Fernandez, A.; Gutierrez-Orrantia, M. E.; Lopez de Lacalle, L. N.; Girot, F.
2011-01-01
This paper presents the prediction and evaluation of feed force in routing of carbon composite material. In order to extend tool life and improve quality of the machined surface, a better understanding of uncoated and coated tool behaviors is required. This work describes (1) the optimization of the geometry of multiple teeth tools minimizing the tool wear and the feed force, (2) the optimization of tool coating and (3) the development of a phenomenological model between the feed force, the routing parameters and the tool wear. The experimental results indicate that the feed rate, the cutting speed and the tool wear are the most significant factors affecting the feed force. In the case of multiple teeth tools, a particular geometry with 14 teeth right helix right cut and 11 teeth left helix right cut gives the best results. A thick AlTiN coating or a diamond coating can dramatically improve the tool life while minimizing the axial force, roughness and delamination. A wear model has then been developed based on an abrasive behavior of the tool. The model links the feed rate to the tool geometry parameters (tool diameter), to the process parameters (feed rate, cutting speed and depth of cut) and to the wear. The model presented has been verified by experimental tests.
Polyelectrolytes thermodynamics and rheology
P M, Visakh; Picó, Guillermo Alfredo
2014-01-01
This book discusses current development of theoretical models and experimental findings on the thermodynamics of polyelectrolytes. Particular emphasis is placed on the rheological description of polyelectrolyte solutions and hydrogels.
Directory of Open Access Journals (Sweden)
João Manuel Marques Cordeiro
1998-11-01
Full Text Available Classical Monte Carlo simulations were carried out on the NPT ensemble at 25°C and 1 atm, aiming to investigate the ability of the TIP4P water model [Jorgensen, Chandrasekhar, Madura, Impey and Klein; J. Chem. Phys., 79 (1983 926] to reproduce the newest structural picture of liquid water. The results were compared with recent neutron diffraction data [Soper; Bruni and Ricci; J. Chem. Phys., 106 (1997 247]. The influence of the computational conditions on the thermodynamic and structural results obtained with this model was also analyzed. The findings were compared with the original ones from Jorgensen et al [above-cited reference plus Mol. Phys., 56 (1985 1381]. It is notice that the thermodynamic results are dependent on the boundary conditions used, whereas the usual radial distribution functions g(O/O(r and g(O/H(r do not depend on them.
Energy Technology Data Exchange (ETDEWEB)
Backman, R. [Aabo Akademi, Turku (Finland); Eriksson, G. [LTH/RWTH (Germany); Sundstroem, K. [Tampella Power Oy, Tampere (Finland)
1996-12-31
The Aabo Advisor is a computer based program intended to provide information about the high temperature ash and fluegas chemistry in pulping spent black liquor recovery boilers of kraft pulp mills. The program can be used for predictions of a variety of furnace and flue gas phenomena, such as fireside fouling of the heat exchanger surfaces caused by the flue gas particulate matter, emissions of SO{sub 2}(g), HCl(g) and NO{sub x}(g) with the flue gas etc. The program determines the composition of the fluegas as well as the amount and composition of the two typical fly ash fractions found in recovery boiler fluegases, the condensed fly ash particles and the carry over particles. These data are used for calculating the melting behavior of the fly ash present at different locations in the boiler and this characteristic behavior is used for the fireside fouling predictions. The program may also be used for studying how different mill processes affecting the black liquor composition affects on the fireside chemistry of the recovery boiler. As input data for the calculations only a few boiler operation parameters and the composition of the black liquor is required. The calculations are based on a one-dimensional, multi-stage chemistry model where both thermodynamic equilibrium calculations and stoichiometric material balances are used. The model calculates at first the chemistry in the lower furnace and smelt after which it moves to the upper furnace and the radiative parts of the fluegas channel. As the last block the program calculates the chemistry in the convective part, the electrostatic precipitator cath and stack. The results from each block are presented in tables, key numbers and melt curves representing the fluegas or fly ash fraction present at each location
Energy Technology Data Exchange (ETDEWEB)
Buragohain, Buljit; Mahanta, Pinakeswar; Moholkar, Vijayanand S. [Center for Energy, Indian Institute of Technology Guwahati, Guwahati - 781 039, Assam (India)
2011-07-01
Biomass gasifiers with power generation capacities exceeding 1 MW have large biomass consumption. Availability of a single biomass in such large quantities is rather difficult, and hence, mixtures of biomasses need to be used as feed-stock for these gasifiers. This study has assessed feasibility of biomass mixtures as fuel in biomass gasifiers for decentralized power generation using thermodynamic equilibrium and semi-equilibrium (with limited carbon conversion) model employing Gibbs energy minimization. Binary mixtures of common biomasses found in northeastern states of India such as rice husk, bamboo dust and saw dust have been taken for analysis. The potential for power generation from gasifier has been evaluated on the basis of net yield (in Nm3) and LHV (in MJ/Nm3) of the producer gas obtained from gasification of 100 g of biomass mixture. The results of simulations have revealed interesting trends in performance of gasifiers with operating parameters such as air ratio, temperature of gasification and composition of the biomass mixture. For all biomass mixtures, the optimum air ratio is {approx} 0.3 with gasification temperature of 800oC. Under total equilibrium conditions, and for engine-generator efficiency of 30%, the least possible fuel consumption is found to be 0.8 kg/kW-h. As revealed in the simulations with semi-equilibrium model, this parameter shows an inverse variation with the extent of carbon conversion. For low carbon conversions ({approx} 60% or so), the specific fuel consumption could be as high as 1.5 kg/kW-h. The results of this study have also been compared with previous literature (theoretical as well as experimental) and good agreement has been found. This study, thus, has demonstrated potential of replacement of a single biomass fuel in the gasifier with mixtures of different biomasses.
Effective site-energy model: A thermodynamic approach applied to size-mismatched alloys
Berthier, F.; Creuze, J.; Legrand, B.
2017-06-01
We present a novel energetic model that takes into account atomistic relaxations to describe the thermodynamic properties of AcB1 -c binary alloys. It requires the calculation of the energies on each site of a random solid solution after relaxation as a function of both the local composition and the nominal concentration. These site energies are obtained by molecular static simulations using N -body interatomic potentials derived from the second-moment approximation (SMA) of the tight-binding scheme. This new model allows us to determine the effective pair interactions (EPIs) that drive the short-range order (SRO) and to analyze the relative role of the EPIs' contribution to the mixing enthalpy, with respect to the contribution due to the lattice mismatch between the constituents. We apply this formalism to Au-Ni and Ag-Cu alloys, both of them tending to phase separate in the bulk and exhibiting a large size mismatch. Rigid-lattice Monte Carlo (MC) simulations lead to phase diagrams that are in good agreement with both those obtained by off-lattice SMA-MC simulations and the experimental ones. While the phase diagrams of Au-Ni and Ag-Cu alloys are very similar, we show that phase separation is mainly driven by the elastic contribution for Au-Ni and by the EPIs' contribution for Ag-Cu. Furthermore, for Au-Ni, the analysis of the SRO shows an inversion between the tendency to order and the tendency to phase separate as a function of the concentration.
Integrating decision management with UML modeling concepts and tools
DEFF Research Database (Denmark)
Könemann, Patrick
2009-01-01
Numerous design decisions including architectural decisions are made while developing a software system, which influence the architecture of the system as well as subsequent decisions. Several tools already exist for managing design decisions, i.e. capturing, documenting, and maintaining them......, but also for guiding the user by proposing subsequent decisions. In model-based software development, many decisions directly affect the structural and behavioral models used to describe and develop a software system and its architecture. However, the decisions are typically not connected to these models....... In this paper, we propose an integration of a decision management and a UML-based modeling tool, based on use cases we distill from an example: the UML modeling tool shall show all decisions related to a model and allow extending or updating them; the decision management tool shall trigger the modeling tool...
Angle, John
2011-01-01
The Inequality Process (IP) and the Saved Wealth Model (SW) are particle system models of income distribution. The IP’s social science meta-theory requires its stationary distribution to fit the distribution of labor income conditioned on education. The Saved Wealth Model (SW) is an ad hoc modification of the particle system model of the Kinetic Theory of Gases (KTG). The KTG implies the laws of gas thermodynamics. The IP is a particle system similar to the SW and KTG, but less closely relate...
Mirmehrabi, Mahmoud; Rohani, Sohrab; Perry, Luisa
2006-04-01
A new activity coefficient model was developed from excess Gibbs free energy in the form G(ex) = cA(a) x(1)(b)...x(n)(b). The constants of the proposed model were considered to be function of solute and solvent dielectric constants, Hildebrand solubility parameters and specific volumes of solute and solvent molecules. The proposed model obeys the Gibbs-Duhem condition for activity coefficient models. To generalize the model and make it as a purely predictive model without any adjustable parameters, its constants were found using the experimental activity coefficient and physical properties of 20 vapor-liquid systems. The predictive capability of the proposed model was tested by calculating the activity coefficients of 41 binary vapor-liquid equilibrium systems and showed good agreement with the experimental data in comparison with two other predictive models, the UNIFAC and Hildebrand models. The only data used for the prediction of activity coefficients, were dielectric constants, Hildebrand solubility parameters, and specific volumes of the solute and solvent molecules. Furthermore, the proposed model was used to predict the activity coefficient of an organic compound, stearic acid, whose physical properties were available in methanol and 2-butanone. The predicted activity coefficient along with the thermal properties of the stearic acid were used to calculate the solubility of stearic acid in these two solvents and resulted in a better agreement with the experimental data compared to the UNIFAC and Hildebrand predictive models.
International Nuclear Information System (INIS)
Tao, D.P.
2004-01-01
Based on the free volume theory and the lattice model, the partition functions of pure solids and their mixtures were expressed. This resulted in the establishment of a thermodynamic model for solid solutions. The model naturally combines the excess entropy and excess enthalpy of a solution by means of new expressions of the configurational partition functions of solids and their mixtures derived from statistical thermodynamics, which is approximate to real solid solutions, that is S E ≠0 (V E ≠0) and H E ≠0. It can describe the thermodynamic properties of partially miscible systems and predict the thermodynamic properties in a multicomponent solid solution system using only the related binary infinite dilute activity coefficients. The predicted activity coefficients from the model are in good agreement with the experimental data of the ternary solid dilutions. This shows that the prediction effect of the proposed model is of better stability and reliability because it has a good physical basis
Student Model Tools Code Release and Documentation
DEFF Research Database (Denmark)
Johnson, Matthew; Bull, Susan; Masci, Drew
of its strengths and areas of improvement (Section 6). Several key appendices are attached to this report including user manuals for teacher and students (Appendix 3). Fundamentally, all relevant information is included in the report for those wishing to do further development work with the tool...
Thermodynamic geometry, condensation and Debye model of two-parameter deformed statistics
Mohammadzadeh, Hosein; Azizian-Kalandaragh, Yashar; Cheraghpour, Narges; Adli, Fereshteh
2017-08-01
We consider the statistical distribution function of a two parameter deformed system, namely qp-deformed bosons and fermions. Using a thermodynamic geometry approach, we derive the thermodynamic curvature of an ideal gas with particles obeying qp-bosons and qp-fermions. We show that the intrinsic statistic interaction of qp-bosons is attractive in all physical ranges, while it is repulsive for qp-fermions. Also, the thermodynamic curvature of qp-boson gas is singular at a specified value of fugacity and therefore, a phase transition such as Bose-Einstein condensation can take place. In the following, we compare the experimental and theoretical results of temperature-dependent specific heat capacity of some metallic materials in the framework of q and qp-deformed algebras.
Olander, Donald
2007-01-01
The book’s methodology is unified, concise, and multidisciplinary, allowing students to understand how the principles of thermodynamics apply to all technical fields that touch upon this most fundamental of scientific theories. It also offers a rigorous approach to the quantitative aspects of thermodynamics, accompanied by clear explanations to help students transition smoothly from the physical concepts to their mathematical representations
International Nuclear Information System (INIS)
Mansson, B.A.
1990-01-01
Economics, as the social science most concerned with the use and distribution of natural resources, must start to make use of the knowledge at hand in the natural sciences about such resources. In this, thermodynamics is an essential part. In a physicists terminology, human economic activity may be described as a dissipative system which flourishes by transforming and exchanging resources, goods and services. All this involves complex networks of flows of energy and materials. This implies that thermodynamics, the physical theory of energy and materials flows, must have implications for economics. On another level, thermodynamics has been recognized as a physical theory of value, with value concepts similar to those of economic theory. This paper discusses some general aspects of the significance of non-equilibrium thermodynamics for economics. The role of exergy, probably the most important of the physical measures of value, is elucidated. Two examples of integration of thermodynamics with economic theory are reviewed. First, a simple model of a steady-state production system is sued to illustrate the effects of thermodynamic process constraints. Second, the framework of a simple macroeconomic growth model is used to illustrate how some thermodynamic limitations may be integrated in macroeconomic theory
Withag, Jan A.M.; Smeets, Jules R.; Bramer, Eduard A.; Brem, Gerrit
2012-01-01
This article presents a system model for the process of gasification of biomass model compounds in supercritical water. Supercritical water gasification of wet biomass (water content of 70 wt% or more) has as the main advantage that conversion may take place without the costly drying step. The
Thermodynamic modelling of unloaded and loaded N,N-diethylethanolamine solutions
Directory of Open Access Journals (Sweden)
Monica Garcia
2016-10-01
Full Text Available Chemical absorption is a crucial step for several chemical processes such as ammonia production, coal gasification, methane reforming, ethylene oxide manufacturing and treatment of associated gas streams [1]. It is considered one of the main processes to eliminate CO2 emissions from power plants by post-combustion.Use of new solvents are of high interest in chemical absorption for carbon capture. For the design of the absorption and desorption columns it is essential to know the vapourâliquid equilibrium (VLE, heat of absorption and densities. N,N-diethylethanolamine (DEEA appeared as one of the amines with the lowest amount of energy needed for its regeneration [2], which would directly decrease the operation costs. DEEA has a high CO2 loading of 1Â mol/mol of amine compared to the traditional MEA solvent (0.5Â mol/mol amine and is obtained from renewable sources [1]. The main weakness is its low absorption rate and consequently the use of promoters is desirable.In this work, a thermodynamic model based on the electrolyte non-random two-liquid theory (eNRTL was created and fitted to correlate and predict the partial and total pressures of the unloaded and loaded aqueous DEEA solutions. New interaction parameters were obtained for the binary and tertiary system. This model represents the vapour pressures of the pure components, DEEA and H2O, with AARD of 1.9% and 1.73% respectively. Furthermore, the fitted model predicts the total pressure above the binary system, H2O-DEEA, with AARD of 0.05%. The excess of enthalpy and densities are predicted with AARD of 5.63% and 1.38% respectively. The tertiary system, H2O-DEEA-CO2, is fitted for 2Â M and 5Â M DEEA solutions with loading between 0.042 and 0.9Â mol CO2/mol amine up to 80Â Â°C. Results of CO2 partial pressures and total pressures are reproduced, with AARD of 19.45% and 16.18% respectively. Densities are predicted with an AARD of 1.52%. Keywords: DEEA, CO2 capture, Chemical
Autothermal reforming of palm empty fruit bunch bio-oil: thermodynamic modelling
Directory of Open Access Journals (Sweden)
Lifita N. Tande
2016-01-01
Full Text Available This work focuses on thermodynamic analysis of the autothermal reforming of palm empty fruit bunch (PEFB bio-oil for the production of hydrogen and syngas. PEFB bio-oil composition was simulated using bio-oil surrogates generated from a mixture of acetic acid, phenol, levoglucosan, palmitic acid and furfural. A sensitivity analysis revealed that the hydrogen and syngas yields were not sensitive to actual bio-oil composition, but were determined by a good match of molar elemental composition between real bio-oil and surrogate mixture. The maximum hydrogen yield obtained under constant reaction enthalpy and pressure was about 12 wt% at S/C = 1 and increased to about 18 wt% at S/C = 4; both yields occurring at equivalence ratio Φ of 0.31. The possibility of generating syngas with varying H2 and CO content using autothermal reforming was analysed and application of this process to fuel cells and Fischer-Tropsch synthesis is discussed. Using a novel simple modelling methodology, reaction mechanisms were proposed which were able to account for equilibrium product distribution. It was evident that different combinations of reactions could be used to obtain the same equilibrium product concentrations. One proposed reaction mechanism, referred to as the ‘partial oxidation based mechanism’ involved the partial oxidation reaction of the bio-oil to produce hydrogen, with the extent of steam reforming and water gas shift reactions varying depending on the amount of oxygen used. Another proposed mechanism, referred to as the ‘complete oxidation based mechanism’ was represented by thermal decomposition of about 30% of bio-oil and hydrogen production obtained by decomposition, steam reforming, water gas shift and carbon gasification reactions. The importance of these mechanisms in assisting in the eventual choice of catalyst to be used in a real ATR of PEFB bio-oil process was discussed.
Energy recovery from human faeces via gasification: A thermodynamic equilibrium modelling approach.
Onabanjo, T; Patchigolla, K; Wagland, S T; Fidalgo, B; Kolios, A; McAdam, E; Parker, A; Williams, L; Tyrrel, S; Cartmell, E
2016-06-15
Non-sewered sanitary systems (NSS) are emerging as one of the solutions to poor sanitation because of the limitations of the conventional flush toilet. These new sanitary systems are expected to safely treat faecal waste and operate without external connections to a sewer, water supply or energy source. The Nano Membrane Toilet (NMT) is a unique domestic-scale sanitary solution currently being developed to treat human waste on-site. This toilet will employ a small-scale gasifier to convert human faeces into products of high energy value. This study investigated the suitability of human faeces as a feedstock for gasification. It quantified the recoverable exergy potential from human faeces and explored the optimal routes for thermal conversion, using a thermodynamic equilibrium model. Fresh human faeces were found to have approximately 70-82 wt.% moisture and 3-6 wt.% ash. Product gas resulting from a typical dry human faeces (0 wt.% moisture) had LHV and exergy values of 17.2 MJ/kg and 24 MJ/kg respectively at optimum equivalence ratio of 0.31, values that are comparable to wood biomass. For suitable conversion of moist faecal samples, near combustion operating conditions are required, if an external energy source is not supplied. This is however at 5% loss in the exergy value of the gas, provided both thermal heat and energy of the gas are recovered. This study shows that the maximum recoverable exergy potential from an average adult moist human faeces can be up to 15 MJ/kg, when the gasifier is operated at optimum equivalence ratio of 0.57, excluding heat losses, distribution or other losses that result from operational activities.
Thermodynamic model to study a solar collector for its application to Stirling engines
International Nuclear Information System (INIS)
Abdollahpour, Amir; Ahmadi, Mohammad H.; Mohammadi, Amir H.
2014-01-01
Highlights: • A thermodynamic model is presented to study a solar collector for its application to Stirling engines. • The parabolic collector is analyzed based on optical and thermal. • Effects of changing some conditions and parameters are studied. - Abstract: Energy production through clean and green sources has been paid attention over the last decades owing to high energy consumption and environmental emission. Solar energy is one of the most useful energy sources. Due to high investment cost of centralized generation of electricity and considerable loss in the network, it is necessary to look forward to decentralized electricity generation technologies. Stirling engines have high efficiency and are able to be coupled with solar energy which cannot be applied in internal combustion engines. Solar Stirling engines can be commercialized and used to generate decentralized electricity in small to medium levels. One of the most important steps to set up an efficient solar Stirling engine is choosing and designing the collector. In this study, a solar parabolic collector with 3500 W of power for its application to Stirling engines was designed and analyzed (It is the thermal inlet power for a Stirling engine). We studied the parabolic collector based on optical and thermal analysis. In this case, solar energy is focused by a concentrating mirror and transferred to a pipe containing fluid. MATLAB software was used for obtaining the parameters of the collector, with respect to the geographic, temporal, and environmental conditions, fluid inlet temperature and some other considerations. After obtaining the results of the design, we studied the effects of changing some conditions and parameters such as annular space pressure, type of the gas, wind velocity, environment temperature and absorber pipe coating
Computer-Aided Modelling Methods and Tools
DEFF Research Database (Denmark)
Cameron, Ian; Gani, Rafiqul
2011-01-01
. To illustrate these concepts a number of examples are used. These include models of polymer membranes, distillation and catalyst behaviour. Some detailed considerations within these models are stated and discussed. Model generation concepts are introduced and ideas of a reference model are given that shows...
Large scale experiments as a tool for numerical model development
DEFF Research Database (Denmark)
Kirkegaard, Jens; Hansen, Erik Asp; Fuchs, Jesper
2003-01-01
for improvement of the reliability of physical model results. This paper demonstrates by examples that numerical modelling benefits in various ways from experimental studies (in large and small laboratory facilities). The examples range from very general hydrodynamic descriptions of wave phenomena to specific......Experimental modelling is an important tool for study of hydrodynamic phenomena. The applicability of experiments can be expanded by the use of numerical models and experiments are important for documentation of the validity of numerical tools. In other cases numerical tools can be applied...... hydrodynamic interaction with structures. The examples also show that numerical model development benefits from international co-operation and sharing of high quality results....
Advanced reach tool (ART) : Development of the mechanistic model
Fransman, W.; Tongeren, M. van; Cherrie, J.W.; Tischer, M.; Schneider, T.; Schinkel, J.; Kromhout, H.; Warren, N.; Goede, H.; Tielemans, E.
2011-01-01
This paper describes the development of the mechanistic model within a collaborative project, referred to as the Advanced REACH Tool (ART) project, to develop a tool to model inhalation exposure for workers sharing similar operational conditions across different industries and locations in Europe.
Storm Water Management Model Climate Adjustment Tool (SWMM-CAT)
The US EPA’s newest tool, the Stormwater Management Model (SWMM) – Climate Adjustment Tool (CAT) is meant to help municipal stormwater utilities better address potential climate change impacts affecting their operations. SWMM, first released in 1971, models hydrology and hydrauli...
Mathematical Model Based on Newton’s Laws and in First Thermodynamic Law of a Gas Turbine
Ottmar Rafael Uriza Gosebruch; Carlos Alexander Nuñez Martin; Eloy Edmundo Rodríguez Vázquez; Eduardo Campos Mercado
2017-01-01
The present article explains the modeling of a Gas Turbine system; the mathematical modeling is based on fluid mechanics applying the principal energy laws such as Euler’s Law, Newton’s second Law and the first thermodynamic law to obtain the equations for mass, momentum and energy conservation; expressed as the continuity equation, the Navier-Stokes equation and the energy conservation using Fourier’s Law. The purpose of this article is to establish a precise mathematical model to be applied...
Mathematical Model Based on Newton’s Laws and in First Thermodynamic Law of a Gas Turbine
Directory of Open Access Journals (Sweden)
Ottmar Rafael Uriza Gosebruch
2017-09-01
Full Text Available The present article explains the modeling of a Gas Turbine system; the mathematical modeling is based on fluid mechanics applying the principal energy laws such as Euler’s Law, Newton’s second Law and the first thermodynamic law to obtain the equations for mass, momentum and energy conservation; expressed as the continuity equation, the Navier-Stokes equation and the energy conservation using Fourier’s Law. The purpose of this article is to establish a precise mathematical model to be applied in control applications, for future works, within industry applications.
Dynamic wind turbine models in power system simulation tool
DEFF Research Database (Denmark)
Hansen, A.; Jauch, Clemens; Soerensen, P.
The present report describes the dynamic wind turbine models implemented in the power system simulation tool DIgSILENT. The developed models are a part of the results of a national research project, whose overall objective is to create a model database in different simulation tools. The report...... provides a description of the wind turbine modelling, both at a component level and at a system level....
Bellot, J C.; Choisnard, L; Castillo, E; Marty, A
2001-03-08
Monoglyceride synthesis by Rhyzomucor miehei lipase was investigated via direct esterification between glycerol (adsorbed onto silica gel) and oleic acid in organic solvents. The main difficulty is to avoid the unwanted production of di- and tri-glycerides. It was demonstrated that an increase in solvent polarity, using mixtures of n-hexane and 2-methyl-2-butanol (2M2B), improves drastically the selectivity toward monoglyceride formation. In pure n-hexane, the monoglyceride represents only 6 molar % of the total products at the thermodynamic equilibrium (34 and 60% for di- and tri-glyceride respectively). Use of an equivolume mixture of n-hexane/2M2B enables a product mixture to be obtained containing 94% of monoglyceride at equilibrium (2.4 and 0% for di- and tri-glyceride respectively). This positive effect is counterbalanced by a decrease both in initial velocities and in substrate conversion at thermodynamic equilibrium.A modeling, able to predict the three thermodynamic equilibria governing the 3 consecutive reactions, based on activity coefficient calculations using the UNIFAC model, is proposed. It takes into account both the partition of water between solvent and immobilized catalyst, and the partition of glycerol between solvent and silica gel. A good correlation with experimental data obtained in n-hexane/2M2B mixtures was observed.
Digital Repository Service at National Institute of Oceanography (India)
Nakamoto, S.; PrasannaKumar, S.; Oberhuber, J.M.; Saito, H.; Muneyama, K.
and supported by quasi-steady upwelling. Remotely sensed chlorophyll pigment concentrations from the Coastal Zone Color Scanner (CZCS) are used to investigate the chlorophyll modulation of ocean mixed layer thermodynamics in a bulk mixed-layer model, embedded...
Cantera and Cantera Electrolyte Thermodynamics Objects
Energy Technology Data Exchange (ETDEWEB)
2015-10-19
Cantera is a suite of object-oriented software tools for problems involving chemical kinetics, thermodynamics, and/or transport processes. It is a multi-organizational effort to create and formulate high quality 0D and 1D constitutive modeling tools for reactive transport codes.Institutions involved with the effort include Sandia, MIT, Colorado School of Mines, U. Texas, NASA, and Oak Ridge National Labs. Specific to Sandia's contributions, the Cantera Electrolyte Thermo Objects (CETO) packages is comprised of add-on routines for Cantera that handle electrolyte thermochemistry and reactions within the overall Cantera package. Cantera is a C++ Cal Tech code that handles gas phase species transport, reaction, and thermodynamics. With this addition, Cantera can be extended to handle problems involving liquid phase reactions and transport in electrolyte systems, and phase equilibrium problemsinvolving concentrated electrolytes and gas/solid phases. A full treatment of molten salt thermodynamics and transport has also been implemented in CETO. The routines themselves consist of .cpp and .h files containing C++ objects that are derived from parent Cantera objects representing thermodynamic functions. They are linked unto the main Cantera libraries when requested by the user. As an addendum to the main thermodynamics objects, several utility applications are provided. The first is multiphase Gibbs free energy minimizer based on the vcs algorithm, called vcs_cantera. This code allows for the calculation of thermodynamic equilibrium in multiple phases at constant temperature and pressure. Note, a similar code capability exists already in Cantera. This version follows the same algorithm, but gas a different code-base starting point, and is used as a research tool for algorithm development. The second program, cttables, prints out tables of thermodynamic and kinetic information for thermodynamic and kinetic objects within Cantera. This program serves as a "Get the
The scientific modeling assistant: An advanced software tool for scientific model building
Keller, Richard M.; Sims, Michael H.
1991-01-01
Viewgraphs on the scientific modeling assistant: an advanced software tool for scientific model building are presented. The objective is to build a specialized software tool to assist in scientific model-building.
Thermodynamic modeling and experimental study of alkali-activated slag paste
Zuo, Y.; Nedeljkovic, M.; Arbi Ghanmi, K.; Ye, G.; Fehling, Ekkehard; Middendorf, Bernhard; Thiemicke, Jenny
2016-01-01
A newly developed thermodynamic approach was introduced from the literature to investigate the influence of NaOH content on the hydrate assemblage and chemistry of aqueous solution of activated slag paste (Na2O/slag=4%, 6% and 8%). The ICP-OES test was performed to obtain the aqueous species
Modelling of physical and thermodynamic properties in systems containing edible oils and biodiesel
DEFF Research Database (Denmark)
Cunico, Larissa; Ceriani, Roberta; Sarup, Bent
The knowledge of physical and thermodynamic properties of pure components and their mixtures is a basic requirement for performing tasks related to process design, simulation, and optimization and also for performing chemical product design using computer aided molecular/mixture design (CAMD) too...
Samuel A. Cushman
2015-01-01
Entropy and the second law of thermodynamics are the central organizing principles of nature. Or perhaps more accurately, the second law is the central disorganizing principle. Hot things cool down. Cold things warm up. You cannot get something for nothing. You always pay more than you get. Things fall apart. You cannot repeat the past. We grow old and die. It is all...
Scratch as a computational modelling tool for teaching physics
Lopez, Victor; Hernandez, Maria Isabel
2015-05-01
The Scratch online authoring tool, which features a simple programming language that has been adapted to primary and secondary students, is being used more and more in schools as it offers students and teachers the opportunity to use a tool to build scientific models and evaluate their behaviour, just as can be done with computational modelling programs. In this article, we briefly discuss why Scratch could be a useful tool for computational modelling in the primary or secondary physics classroom, and we present practical examples of how it can be used to build a model.
Shape: A 3D Modeling Tool for Astrophysics.
Steffen, Wolfgang; Koning, Nicholas; Wenger, Stephan; Morisset, Christophe; Magnor, Marcus
2011-04-01
We present a flexible interactive 3D morpho-kinematical modeling application for astrophysics. Compared to other systems, our application reduces the restrictions on the physical assumptions, data type, and amount that is required for a reconstruction of an object's morphology. It is one of the first publicly available tools to apply interactive graphics to astrophysical modeling. The tool allows astrophysicists to provide a priori knowledge about the object by interactively defining 3D structural elements. By direct comparison of model prediction with observational data, model parameters can then be automatically optimized to fit the observation. The tool has already been successfully used in a number of astrophysical research projects.
Directory of Open Access Journals (Sweden)
Enrique D. Fernández-Nieto
2012-07-01
Full Text Available Traditionally, people in the Mediterranean region knew that the temperatures in their courtyards were cooler in summer than outside temperature. This paper provides a quantitative study on the usefulness of Mediterranean courtyards as passive energy saving systems. This work is based on the creation of a Computational Fluid Dynamics (CFD numerical model developed using the open source Freefem++ language. In this work, first the numerical model is tested using simplified-shape courtyards which have been previously studied both physically under controlled parameters, and mathematically through numerical simulations. We also study the most appropriate depth ratio for a courtyard, based on these simplified shapes, depending on the climate. Secondly, we apply the numerical model in a real geometry, the Monte Málaga hotel. We compare the numerical results with the monitored data of the temperature in the courtyard of the hotel. The numerical model takes into account precomputed solar radiation in the walls of the courtyard, the predominant wind and buoyancy effects.
Mohamed, Samah
2016-03-21
Accurate chemical kinetic combustion models of lightly branched alkanes (e.g., 2-methylalkanes) are important to investigate the combustion behavior of real fuels. Improving the fidelity of existing kinetic models is a necessity, as new experiments and advanced theories show inaccuracies in certain portions of the models. This study focuses on updating thermodynamic data and the kinetic reaction mechanism for a gasoline surrogate component, 2-methylhexane, based on recently published thermodynamic group values and rate rules derived from quantum calculations and experiments. Alternative pathways for the isomerization of peroxy-alkylhydroperoxide (OOQOOH) radicals are also investigated. The effects of these updates are compared against new high-pressure shock tube and rapid compression machine ignition delay measurements. It is shown that rate constant modifications are required to improve agreement between kinetic modeling simulations and experimental data. We further demonstrate the ability to optimize the kinetic model using both manual and automated techniques for rate parameter tunings to improve agreement with the measured ignition delay time data. Finally, additional low temperature chain branching reaction pathways are shown to improve the model’s performance. The present approach to model development provides better performance across extended operating conditions while also strengthening the fundamental basis of the model.
Patel, Shruti V; Patel, Sarsvatkumar
2015-09-18
Self-micro emulsifying drug delivery system (SMEDDS) is one of the methods to improve solubility and bioavailability of poorly soluble drug(s). The knowledge of the solubility of pharmaceuticals in pure lipidic solvents and solvent mixtures is crucial for designing the SMEDDS of poorly soluble drug substances. Since, experiments are very time consuming, a model, which allows for solubility predictions in solvent mixtures based on less experimental data is desirable for efficiency. Solvents employed were Labrafil® M1944CS and Labrasol® as lipidic solvents; Capryol-90®, Capryol-PGMC® and Tween®-80 as surfactants; Transcutol® and PEG-400 as co-solvents. Solubilities of both drugs were determined in single solvent systems at temperature (T) range of 283-333K. In present study, we investigated the applicability of the thermodynamic model to understand the solubility behavior of drugs in the lipiodic solvents. By using the Van't Hoff and general solubility theory, the thermodynamic functions like Gibbs free energy, enthalpy and entropy of solution, mixing and solvation for drug in single and mixed solvents were understood. The thermodynamic parameters were understood in the framework of drug-solvent interaction based on their chemical similarity and dissimilarity. Clotrimazole and Fluconazole were used as active ingredients whose solubility was measured in single solvent as a function of temperature and the data obtained were used to derive mathematical models which can predict solubility in multi-component solvent mixtures. Model dependent parameters for each drug were calculated at each temperature. The experimental solubility data of solute in mixed solvent system were measured experimentally and further correlated with the calculates values obtained from exponent model and log-linear model of Yalkowsky. The good correlation was observed between experimental solubility and predicted solubility. Copyright © 2015 Elsevier B.V. All rights reserved.
Spatial Modeling Tools for Cell Biology
2006-10-01
of the cells total volume. The cytosol contains thousands of enzymes that are responsible for the catalyzation of glycolysis and gluconeogenesis ... dog , swine and pig models [Pantely, 1990, 1991; Stanley 1992]. In these studies, blood flow through the left anterior descending (LAD) coronary...perfusion. In conclusion, even thought our model falls within the (rather large) error bounds of experimental dog , pig and swine models, the
Welland, M. J.; Tenuta, E.; Prudil, A. A.
2017-06-01
This article describes a phase-field model for an isothermal multicomponent, multiphase system which avoids implicit interfacial energy contributions by starting from a grand potential formulation. A method is developed for incorporating arbitrary forms of the equilibrium thermodynamic potentials in all phases to determine an explicit relationship between chemical potentials and species concentrations. The model incorporates variable densities between adjacent phases, defect migration, and dependence of internal pressure on object dimensions ranging from the macro- to nanoscale. A demonstrative simulation of an overpressurized nanoscopic intragranular bubble in nuclear fuel migrating to a grain boundary under kinetically limited vacancy diffusion is shown.
Kar, Sujoy Kumar; Dheeradhada, Voramon S.; Lipkin, Don M.
2013-08-01
Alloys in the Mo-rich corner of the Mo-Ti-Zr-C system have found broad applications in non-oxidizing environments requiring structural integrity well beyond 1273 K (1000 °C). Alloys such as TZM (Mo-0.5Ti-0.08Zr-0.03C by weight %) and TZC (Mo-1.2Ti-0.3Zr-0.1C by weight) owe much of their high temperature strength and microstructural stability to MC and M2C carbide phases. In turn, the stability of the respective carbides and the subsequent mechanical behavior of the alloys are strongly dependent on the alloying additions and thermal history. A CALPHAD-based thermodynamic modeling approach is employed to develop a quaternary thermodynamic database for the Mo-Ti-Zr-C system. The thermodynamic database thus developed is validated with diffusion multiple experiments and the validated database is exercised to elucidate the effects of alloying and thermal history on the phase equilibrium in Mo-rich alloys.
Mathematical modeling of the complete thermodynamic cycle of a new Atkinson cycle gas engine
International Nuclear Information System (INIS)
Shojaeefard, Mohammad Hassan; Keshavarz, Mojtaba
2015-01-01
The Atkinson cycle provides the potential to increase the efficiency of SI engines using overexpansion concept. This also will suggest decrease in CO 2 generation by internal combustion engine. In this study a mathematical modeling of complete thermodynamic cycle of a new two-stroke Atkinson cycle SI engine will be presented. The mathematical modeling is carried out using two-zone combustion analysis in order to make the model predict exhaust emission so that its values could be compared with the values of conventional SI engine. The model also is validated against experimental tests in that increase in efficiency is achieved compared to conventional SI engines. - Highlights: • The complete cycle model for the rotary Atkinson engine was developed. • Comparing the results with experimental data shows good model validity. • The model needs further improvement for the scavenging phase. • There is 5% increment in thermal efficiency with new engine compared to conventional SI engines.
International Nuclear Information System (INIS)
Mohammadi, Mohsen; Haghtalab, Ali; Fakhroueian, Zahra
2016-01-01
Highlights: • Nanofluids enhance heat and mass transfer and affect on kinetic and thermodynamics. • The ZnO nanoparticles in liquid affect on kinetics and P-T curve of CO 2 hydrate. • ZnO nanoparticles enhance the growth rate and gas storage in CO 2 hydrate. • A thermodynamic modeling of CO 2 hydrate proposed in the presence of nanoparticles. • Water activity in ZnO + nanofluid was affected by enhancement of the CO 2 solubility. - Abstract: The effect of synthesized zinc oxide (ZnO) nanoparticles was investigated on the kinetic and thermodynamic equilibrium conditions of CO 2 hydrate formation. The amount of the gas consumption was measured and compared for the four sample fluids: pure water, aqueous solution of sodium dodecyl sulfate (SDS), water-based ZnO-nanofluid and water-based ZnO-nanofluid in the presence of SDS (0.001 mass fraction). The time of hydrate growth decreased and the amount of the storage gas enhanced in the presence of nanoparticles. Moreover, the nanoparticles size effect besides the CO 2 solubility enhancement in ZnO-nanofluid led to the reduction of water activity, so that the equilibrium curve of hydrate formation was shifted to higher pressures. A new correlation for Henry’s law constant was obtained using CO 2 -solubility data in ZnO-nanofluid. Finally using this correlation, the water activity was calculated through the Chen–Guo approach to propose a thermodynamic method for prediction of the equilibrium hydrate formation conditions in the presence of the nanoparticles.
Towards a generalized energy prediction model for machine tools.
Bhinge, Raunak; Park, Jinkyoo; Law, Kincho H; Dornfeld, David A; Helu, Moneer; Rachuri, Sudarsan
2017-04-01
Energy prediction of machine tools can deliver many advantages to a manufacturing enterprise, ranging from energy-efficient process planning to machine tool monitoring. Physics-based, energy prediction models have been proposed in the past to understand the energy usage pattern of a machine tool. However, uncertainties in both the machine and the operating environment make it difficult to predict the energy consumption of the target machine reliably. Taking advantage of the opportunity to collect extensive, contextual, energy-consumption data, we discuss a data-driven approach to develop an energy prediction model of a machine tool in this paper. First, we present a methodology that can efficiently and effectively collect and process data extracted from a machine tool and its sensors. We then present a data-driven model that can be used to predict the energy consumption of the machine tool for machining a generic part. Specifically, we use Gaussian Process (GP) Regression, a non-parametric machine-learning technique, to develop the prediction model. The energy prediction model is then generalized over multiple process parameters and operations. Finally, we apply this generalized model with a method to assess uncertainty intervals to predict the energy consumed to machine any part using a Mori Seiki NVD1500 machine tool. Furthermore, the same model can be used during process planning to optimize the energy-efficiency of a machining process.
Thermodynamic control-oriented modeling of cycle-to-cycle exhaust gas temperature in an HCCI engine
International Nuclear Information System (INIS)
Dehghani Firoozabadi, M.; Shahbakhti, M.; Koch, C.R.; Jazayeri, S.A.
2013-01-01
Highlights: • First thermodynamic model in the literature to predict exhaust temperature in HCCI engines. • The model can be used for integrated control of HCCI combustion and exhaust temperature. • The model is experimentally validated at over 300 steady state and transient conditions. • Results show a good agreement between predicted and measured exhaust temperatures. • Sensitivity of exhaust gas temperature to variation of engine variables is shown. - Abstract: Model-based control of Homogenous Charge Compression Ignition (HCCI) engine exhaust temperature is a viable solution to optimize efficiency of both engine and the exhaust aftertreatment system. Low exhaust temperature in HCCI engines can limit the abatement of hydrocarbon (HC) and carbon monoxide (CO) emissions in an exhaust aftertreatment system. A physical–empirical model is described for control of exhaust temperature in HCCI engines. This model captures cycle-to-cycle dynamics affecting exhaust temperature and is based on thermodynamic relations and semi-empirical correlations. It incorporates intake and exhaust gas flow dynamics, residual gas mixing, and fuel burn rate and is validated with experimental data from a single cylinder engine at over 300 steady state and transient conditions. The validation results indicate a good agreement between predicted and measured exhaust gas temperature
Energy Technology Data Exchange (ETDEWEB)
Szewczyk, V.
1997-12-02
The aim of this work is to propose to the oil industry a compositional thermodynamic model able to predict the operating conditions which induce asphaltenes flocculation out of crudes. In this study, various analytical methods (calorimetry, elemental analysis, {sup 13}C nuclear magnetic resonance, neutron diffusion,...) have been used in order to get a better description of the asphaltene fraction to infer its flocculation mechanism. The proposed model describes this flocculation as a thermodynamic transition inducing the formation of a new liquid phase with a high asphaltene content and formed by all the components initially in the crude: the asphaltene deposit. Asphaltenes are represented as a pseudo-component essentially made of carbon and hydrogen. The analytical modelling of the F11-F20 light fraction is the one proposed by Jaubert (1993). The F20+ heavy fraction is represented by four pseudo-components, their physical properties are calculated using the group contribution methods of Avaullee (1995) and of Rogalski and Neau (1990). The Peng-Robinson equation of state (1976) combined with the Abdoul and Peneloux group contribution mixing rules (1989) is used in order to restitute the gas-liquid-asphaltene deposit phase equilibria. This model not being able to compute flocculation conditions on a predictive manner, the method consists in fitting some physical properties of the pseudo-components introduced in the analytical representation of the asphaltene crudes. he obtained results show results show that the proposed flocculation model is then well adapted to the description of the thermodynamic properties (saturation pressures, relative volumes, flocculation curves) of asphaltene crudes within a relatively large range of temperature (30-150 deg C) and pressure (0.1-50 MPa), covering the majority of conditions met in oil production. (author) 109 refs.
Wong, Kaufui Vincent
2011-01-01
Praise for the First Edition from Students: "It is a great thermodynamics text…I loved it!-Mathew Walters "The book is comprehensive and easy to understand. I love the real world examples and problems, they make you feel like you are learning something very practical."-Craig Paxton"I would recommend the book to friends."-Faure J. Malo-Molina"The clear diction, as well as informative illustrations and diagrams, help convey the material clearly to the reader."-Paul C. Start"An inspiring and effective tool for any aspiring scientist or engineer. Definitely the best book on Classical Thermodynamics out."-Seth Marini.
A model of tool wear monitoring system for turning
Šimunović, Goran; Ficko, Mirko; Šarić, Tomislav; Milošević, Mijodrag; Antić, Aco
2015-01-01
Acquiring high-quality and timely information on the tool wear condition in real time, presents a necessary prerequisite for identification of tool wear degree, which significantly improves the stability and quality of the machining process. Defined in this paper is a model of tool wear monitoring system with special emphasis on the module for acquisition and processing of vibration acceleration signal by applying discrete wavelet transformations (DWT) in signal decomposition. The paper prese...
Wei, Bo-Bo; Jiang, Zhan-Feng; Liu, Ren-Bao
2015-10-19
The holographic principle states that the information about a volume of a system is encoded on the boundary surface of the volume. Holography appears in many branches of physics, such as optics, electromagnetism, many-body physics, quantum gravity, and string theory. Here we show that holography is also an underlying principle in thermodynamics, a most important foundation of physics. The thermodynamics of a system is fully determined by its partition function. We prove that the partition function of a finite but arbitrarily large system is an analytic function on the complex plane of physical parameters, and therefore the partition function in a region on the complex plane is uniquely determined by its values along the boundary. The thermodynamic holography has applications in studying thermodynamics of nano-scale systems (such as molecule engines, nano-generators and macromolecules) and provides a new approach to many-body physics.
Energy Technology Data Exchange (ETDEWEB)
Cengel, Y.A. [Nevada Univ., Reno, NV (United States). Dept. of Mechanical Engineering
2006-07-01
Green components of thermodynamics were identified and general aspects of green practices associated with thermodynamics were assessed. Energy uses associated with fossil fuels were reviewed. Green energy sources such as solar, wind, geothermal and hydropower were discussed, as well as biomass plantations. Ethanol production practices were reviewed. Conservation practices in the United States were outlined. Energy efficiency and exergy analyses were discussed. Energy intensity measurements and insulation products for houses were also reviewed. Five case studies were presented to illustrate aspects of green thermodynamics: (1) light in a classroom; (2) fuel saved by low-resistance tires; and (3) savings with high-efficiency motors; (4) renewable energy; and (5) replacing a valve with a turbine at a cryogenic manufacturing facility. It was concluded that the main principles of green thermodynamics are to ensure that all material and energy inputs minimize the depletion of energy resources; prevent waste; and improve or innovate technologies that achieve sustainability. 17 refs., 2 tabs., 9 figs.
Iribarne, J V
1973-01-01
The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...
Wei, Bo-Bo; Jiang, Zhan-Feng; Liu, Ren-Bao
2015-01-01
The holographic principle states that the information about a volume of a system is encoded on the boundary surface of the volume. Holography appears in many branches of physics, such as optics, electromagnetism, many-body physics, quantum gravity, and string theory. Here we show that holography is also an underlying principle in thermodynamics, a most important foundation of physics. The thermodynamics of a system is fully determined by its partition function. We prove that the partition function of a finite but arbitrarily large system is an analytic function on the complex plane of physical parameters, and therefore the partition function in a region on the complex plane is uniquely determined by its values along the boundary. The thermodynamic holography has applications in studying thermodynamics of nano-scale systems (such as molecule engines, nano-generators and macromolecules) and provides a new approach to many-body physics. PMID:26478214
Energy recovery from human faeces via gasification: A thermodynamic equilibrium modelling approach
International Nuclear Information System (INIS)
Onabanjo, T.; Patchigolla, K.; Wagland, S.T.; Fidalgo, B.; Kolios, A.; McAdam, E.; Parker, A.; Williams, L.; Tyrrel, S.; Cartmell, E.
2016-01-01
Highlights: • On dry basis, typical human faeces contain 83 wt.% organic fraction and 17 wt.% ash. • The LHV of dry human faeces ranged from 19 to 22 MJ/kg, values similar to wood biomass. • Syngas from dry human faeces had LHV of 15–17 MJ/kg at equivalence ratio of ∼0.31. • Energy is best recovered from moist human faeces at equivalence ratio above 0.6. • Recoverable exergy potential from moist human faeces can be up to 15 MJ/kg. - Abstract: Non-sewered sanitary systems (NSS) are emerging as one of the solutions to poor sanitation because of the limitations of the conventional flush toilet. These new sanitary systems are expected to safely treat faecal waste and operate without external connections to a sewer, water supply or energy source. The Nano Membrane Toilet (NMT) is a unique domestic-scale sanitary solution currently being developed to treat human waste on-site. This toilet will employ a small-scale gasifier to convert human faeces into products of high energy value. This study investigated the suitability of human faeces as a feedstock for gasification. It quantified the recoverable exergy potential from human faeces and explored the optimal routes for thermal conversion, using a thermodynamic equilibrium model. Fresh human faeces were found to have approximately 70–82 wt.% moisture and 3–6 wt.% ash. Product gas resulting from a typical dry human faeces (0 wt.% moisture) had LHV and exergy values of 17.2 MJ/kg and 24 MJ/kg respectively at optimum equivalence ratio of 0.31, values that are comparable to wood biomass. For suitable conversion of moist faecal samples, near combustion operating conditions are required, if an external energy source is not supplied. This is however at 5% loss in the exergy value of the gas, provided both thermal heat and energy of the gas are recovered. This study shows that the maximum recoverable exergy potential from an average adult moist human faeces can be up to 15 MJ/kg, when the gasifier is operated at
Experimental validation of a thermodynamic boiler model under steady state and dynamic conditions
International Nuclear Information System (INIS)
Carlon, Elisa; Verma, Vijay Kumar; Schwarz, Markus; Golicza, Laszlo; Prada, Alessandro; Baratieri, Marco; Haslinger, Walter; Schmidl, Christoph
2015-01-01
Highlights: • Laboratory tests on two commercially available pellet boilers. • Steady state and a dynamic load cycle tests. • Pellet boiler model calibration based on data registered in stationary operation. • Boiler model validation with reference to both stationary and dynamic operation. • Validated model suitable for coupled simulation of building and heating system. - Abstract: Nowadays dynamic building simulation is an essential tool for the design of heating systems for residential buildings. The simulation of buildings heated by biomass systems, first of all needs detailed boiler models, capable of simulating the boiler both as a stand-alone appliance and as a system component. This paper presents the calibration and validation of a boiler model by means of laboratory tests. The chosen model, i.e. TRNSYS “Type 869”, has been validated for two commercially available pellet boilers of 6 and 12 kW nominal capacities. Two test methods have been applied: the first is a steady state test at nominal load and the second is a load cycle test including stationary operation at different loads as well as transient operation. The load cycle test is representative of the boiler operation in the field and characterises the boiler’s stationary and dynamic behaviour. The model had been calibrated based on laboratory data registered during stationary operation at different loads and afterwards it was validated by simulating both the stationary and the dynamic tests. Selected parameters for the validation were the heat transfer rates to water and the water temperature profiles inside the boiler and at the boiler outlet. Modelling results showed better agreement with experimental data during stationary operation rather than during dynamic operation. Heat transfer rates to water were predicted with a maximum deviation of 10% during the stationary operation, and a maximum deviation of 30% during the dynamic load cycle. However, for both operational regimes the
Brinson, Thomas E.; Kopasakis, George
2004-01-01
The Controls and Dynamics Technology Branch at NASA Glenn Research Center are interested in combining a solid oxide fuel cell (SOFC) to operate in conjunction with a gas turbine engine. A detailed engine model currently exists in the Matlab/Simulink environment. The idea is to incorporate a SOFC model within the turbine engine simulation and observe the hybrid system's performance. The fuel cell will be heated to its appropriate operating condition by the engine s combustor. Once the fuel cell is operating at its steady-state temperature, the gas burner will back down slowly until the engine is fully operating on the hot gases exhausted from the SOFC. The SOFC code is based on a steady-state model developed by The U.S. Department of Energy (DOE). In its current form, the DOE SOFC model exists in Microsoft Excel and uses Visual Basics to create an I-V (current-voltage) profile. For the project's application, the main issue with this model is that the gas path flow and fuel flow temperatures are used as input parameters instead of outputs. The objective is to create a SOFC model based on the DOE model that inputs the fuel cells flow rates and outputs temperature of the flow streams; therefore, creating a temperature profile as a function of fuel flow rate. This will be done by applying the First Law of Thermodynamics for a flow system to the fuel cell. Validation of this model will be done in two procedures. First, for a given flow rate the exit stream temperature will be calculated and compared to DOE SOFC temperature as a point comparison. Next, an I-V curve and temperature curve will be generated where the I-V curve will be compared with the DOE SOFC I-V curve. Matching I-V curves will suggest validation of the temperature curve because voltage is a function of temperature. Once the temperature profile is created and validated, the model will then be placed into the turbine engine simulation for system analysis.
Systematic Methods and Tools for Computer Aided Modelling
DEFF Research Database (Denmark)
Fedorova, Marina
Models are playing important roles in design and analysis of chemicals/bio-chemicals based products and the processes that manufacture them. Model-based methods and tools have the potential to decrease the number of experiments, which can be expensive and time consuming, and point to candidates......, where the experimental effort could be focused. In this project a general modelling framework for systematic model building through modelling templates, which supports the reuse of existing models via its new model import and export capabilities, have been developed. The new feature for model transfer...... has been developed by establishing a connection with an external modelling environment for code generation. The main contribution of this thesis is a creation of modelling templates and their connection with other modelling tools within a modelling framework. The goal was to create a user...
Phosphorus Control in DRI-EAF Steelmaking: Thermodynamics, Effect of Alumina, and Process Modeling
Tayeb, Mohammed A.
improve. Alumina becomes less acidic acting as a diluting agent and probably forming [AlO6 9-]-octahedra according to which alumina is hypothesized to behave amphoterically. While understanding the equilibrium and kinetics of the phosphorus reaction is important in order to improve the ability to remove phosphorus from the melt, practical use of this understanding in industry is limited. Modeling the phosphorus reaction in steelmaking, however, would result in a better and easier use of conceptual understanding by operators and engineers in plants. This work describes dynamic process models for phosphorus and sulfur reactions when using DRI, scrap, and pig iron in EAF steelmaking. The present models are based on the assumption that thermodynamic equilibrium is locally established at the steel-slag interface, the bulk liquid steel and slag remain homogeneous throughout the reaction, and the rate is predominantly controlled by the mass transfer of phosphorus in the metal and slag boundary layers. The models, which consist of a series of rate and mass balance equations, were converted into a Python code and are capable of predicting trajectories of steel and slag phosphorus and sulfur levels as well as slag chemistry and slag liquid and solid phases. The effect of operating variables on the final phosphorus and sulfur contents, for instance the effect of DRI and pig iron P and S concentrations, oxygen use, temperature, melting rates, and flux addition were tested. The results imply that dephosphorization could be improved by maintaining lower bath temperatures for period of time. Additionally, dephosphorization and desulfurization were improved by higher flux addition.
DEFF Research Database (Denmark)
Tušek, Jaka; Engelbrecht, Kurt; Mañosa, Lluis
2016-01-01
This paper presents direct and indirect methods for studying the elastocaloric effect (eCE) in shape memory materials and its comparison. The eCE can be characterized by the adiabatic temperature change or the isothermal entropy change (both as a function of applied stress/strain). To get...... these quantities, the evaluation of the eCE can be done using either direct methods, where one measures (adiabatic) temperature changes or indirect methods where one can measure the stress–strain–temperature characteristics of the materials and from these deduce the adiabatic temperature and isothermal entropy...... changes. The former can be done using the basic thermodynamic relations, i.e. Maxwell relation and Clausius–Clapeyron equation. This paper further presents basic thermodynamic properties of shape memory materials, such as the adiabatic temperature change, isothermal entropy change and total entropy...
Beretta, G P; Al-Abbasi, Omar; von Spakovsky, M R
2017-04-01
The steepest entropy ascent (SEA) dynamical principle provides a general framework for modeling the dynamics of nonequilibrium (NE) phenomena at any level of description, including the atomistic one. It has recently been shown to provide a precise implementation and meaning to the maximum entropy production principle and to encompass many well-established theories of nonequilibrium thermodynamics into a single unifying geometrical framework. Its original formulation in the framework of quantum thermodynamics (QT) assumes the simplest and most natural Fisher-Rao metric to geometrize from a dynamical standpoint the manifold of density operators, which represent the thermodynamic NE states of the system. This simplest SEAQT formulation is used here to develop a general mathematical framework for modeling the NE time evolution of the quantum state of a chemically reactive mixture at an atomistic level. The method is illustrated for a simple two-reaction kinetic scheme of the overall reaction F+H_{2}⇔HF+F in an isolated tank of fixed volume. However, the general formalism is developed for a reactive system subject to multiple reaction mechanisms. To explicitly implement the SEAQT nonlinear law of evolution for the density operator, both the energy and the particle number eigenvalue problems are set up and solved analytically under the dilute gas approximation. The system-level energy and particle number eigenvalues and eigenstates are used in the SEAQT equation of motion to determine the time evolution of the density operator, thus effectively describing the overall kinetics of the reacting system as it relaxes toward stable chemical equilibrium. The predicted time evolution in the near-equilibrium limit is compared to the reaction rates given by a standard detailed kinetic model so as to extract the single time constant needed by the present SEA model.
International Nuclear Information System (INIS)
Perez, Brenda; Malpiedi, Luciana Pellegrini; Tubío, Gisela; Nerli, Bibiana; Alcântara Pessôa Filho, Pedro de
2013-01-01
Highlights: ► Binodal data of systems (water + polyethyleneglycol + sodium) succinate are reported. ► Pitzer model describes the phase equilibrium of systems formed by polyethyleneglycol and biodegradable salts satisfactorily. ► This simple thermodynamic framework was able to predict the partitioning behaviour of model proteins acceptably well. - Abstract: Phase diagrams of sustainable aqueous two-phase systems (ATPSs) formed by polyethyleneglycols (PEGs) of different average molar masses (4000, 6000, and 8000) and sodium succinate are reported in this work. Partition coefficients (Kps) of seven model proteins: bovine serum albumin, catalase, beta-lactoglobulin, alpha-amylase, lysozyme, pepsin, urease and trypsin were experimentally determined in these systems and in ATPSs formed by the former PEGs and other biodegradable sodium salts: citrate and tartrate. An extension of Pitzer model comprising long and short-range term contributions to the excess Gibbs free energy was used to describe the (liquid + liquid) equilibrium. Comparison between experimental and calculated tie line data showed mean deviations always lower than 3%, thus indicating a good correlation. The partition coefficients were modeled by using the same thermodynamic approach. Predicted and experimental partition coefficients correlated quite successfully. Mean deviations were found to be lower than the experimental uncertainty for most of the assayed proteins.
International Nuclear Information System (INIS)
Hosseinzade, Hadi; Sayyaadi, Hoseyn; Babaelahi, Mojtaba
2015-01-01
Highlights: • A closed-form thermal model was presented for Stirling engines. • The new model was used to simulate the GPU-3 Stirling engine. • Results were compared with experimental data as well as other models. • The new model was more accurate and simple in calculation than other models. • Effects of the engines’ parameters on operation of engine were evaluated. - Abstract: Thermal models for the simulation of Stirling engines need to have greater accuracy along with simple and low-cost calculation. In this regard, a new closed-form thermal model was presented for the thermal simulation of Stirling engines. The new model called PFST (polytropic-finite speed thermodynamics) was developed based on the combination of polytropic analysis of expansion/compression processes and the concept of finite speed thermodynamics (FST). Therefore, compression/expansion works of compression/expansion processes and transferred heat into the heater of Stirling engines were determined based on polytropic analysis, instead of isothermal processes of the ideal Stirling cycle. The calculated work of polytropic processes was corrected to include the effects of internal irreversibilities including pressure throttling in heat exchangers, mechanical friction, and finite motion of the pistons. Output power and thermal efficiency of Stirling engines were calculated as functions of various engine parameters. The developed PFST model was implemented on a prototype Stirling engine, called GPU-3 engine, and the obtained results were compared with those of other closed-form and numerical models as well as experimental data. It was found that the new closed-form model, in addition to its simple and low-cost calculation, had the same order of accuracy as recently developed numerical models
Al Masum, Abdulla; Chakraborty, Maharudra; Ghosh, Soumen; Laha, Dipranjan; Karmakar, Parimal; Islam, Md Maidul; Mukhopadhyay, Subrata
2016-11-01
Interaction of CT DNA with Rhodamine 6G (R6G) has been studied using molecular docking, electrochemical, spectroscopic and thermodynamic methods. From the study, it was illustrated that Rhodamine 6G binds to the minor groove of CT DNA. The binding was cooperative in nature. Circular voltametric study showed significant change in peak current and peak potential due to complexation. All the studies showed that the binding constant was in the order of 10 6 M -1 . Circular dichroic spectra showed significant conformational change on binding and DNA unwind during binding. Thermodynamic study showed that binding was favored by negative enthalpy and positive entropy change. From thermodynamic study it was also observed that several positive and negative free energies played significant role during binding and the unfavorable conformational free energy change was overcame by highly negative hydrophobic and salt dependent free energy changes. The experimental results were further validated using molecular docking study and the effect of structure on binding has been studied theoretically. From docking study it was found that the hydrophobic interaction and hydrogen bonds played a significant role during binding. The dye was absorbed by cell and this phenomenon was studied using fluorescent microscope. Cell survivability test showed that the dye active against Human Breast Cancer cells MDA-MB 468. ROS study showed that the activity is due to the production of reactive oxygen. Copyright © 2016 Elsevier B.V. All rights reserved.
Agent Based Modeling as an Educational Tool
Fuller, J. H.; Johnson, R.; Castillo, V.
2012-12-01
Motivation is a key element in high school education. One way to improve motivation and provide content, while helping address critical thinking and problem solving skills, is to have students build and study agent based models in the classroom. This activity visually connects concepts with their applied mathematical representation. "Engaging students in constructing models may provide a bridge between frequently disconnected conceptual and mathematical forms of knowledge." (Levy and Wilensky, 2011) We wanted to discover the feasibility of implementing a model based curriculum in the classroom given current and anticipated core and content standards.; Simulation using California GIS data ; Simulation of high school student lunch popularity using aerial photograph on top of terrain value map.
Graphical Tools for Linear Structural Equation Modeling
2014-06-01
regression coefficient βS A.CQ1 van- ishes, which can be used to test whether the specification of Model 2 is compatible with the data. Most...because they are all compatible with the graph in Figure 19a, which displays the skeleton and v-structures. Note that we cannot reverse the edge from...im- plications of linear structual equation models. R-428, <http://ftp.cs.ucla.edu/pub/stat_ser/r428.pdf>, CA. To ap- pear in Proceedings of AAAI-2014
Toposcopy : A modelling tool for CITYGML
Groneman, A.; Zlatanova, S.
2009-01-01
The new 3D standard CityGML has been attracting a lot of attention in the last few years. Many characteristics of the XML-based format make it suitable for storage and exchange of virtual 3D city models. It provides possibilities to store semantic and geometric information and has the potential to
Using the IEA ETSAP modelling tools for Denmark
DEFF Research Database (Denmark)
Grohnheit, Poul Erik
-annual workshops focusing on presentations of model analyses and use of the ETSAP' tools (the MARKAL/TIMES family of models). The project was also planned to benefit from the EU project ”NEEDS - New Energy Externalities Developments for Sustainability. ETSAP is contributing to a part of NEEDS that develops......, Environment and Health (CEEH), starting from January 2007. This report summarises the activities under ETSAP Annex X and related project, emphasising the development of modelling tools that will be useful for modelling the Danish energy system. It is also a status report for the development of a model...
International Nuclear Information System (INIS)
Ribeiro, Rafael S.; Hermes, Christian J.L.
2014-01-01
In this study, the method of entropy generation minimization (i.e., design aimed at facilitating both heat, mass and fluid flows) is used to assess the evaporator design (aspect ratio and fin density) considering the thermodynamic losses due to heat and mass transfer, and viscous flow processes. A fully algebraic model was put forward to simulate the thermal-hydraulic behavior of tube-fin evaporator coils running under frosting conditions. The model predictions were validated against experimental data, showing a good agreement between calculated and measured counterparts. The optimization exercise has pointed out that high aspect ratio heat exchanger designs lead to lower entropy generation in cases of fixed cooling capacity and air flow rate constrained by the characteristic curve of the fan. - Highlights: • An algebraic model for frost accumulation on tube-fin heat exchangers was advanced. • Model predictions for cooling capacity and air flow rate were compared with experimental data, with errors within ±5% band. • Minimum entropy generation criterion was used to optimize the evaporator geometry. • Thermodynamic analysis led to slender designs for fixed cooling capacity and fan characteristics
Higuchi, Saki; Kato, Daiki; Awaji, Daisuke; Kim, Kang
2018-03-01
We present a study using molecular dynamics simulations based on the Fermi-Jagla potential model, which is the continuous version of the mono-atomic core-softened Jagla model [J. Y. Abraham, S. V. Buldyrev, and N. Giovambattista, J. Phys. Chem. B 115, 14229 (2011)]. This model shows the water-like liquid-liquid phase transition between high-density and low-density liquids at the liquid-liquid critical point. In particular, the slope of the coexistence line becomes weakly negative, which is expected to represent one of the anomalies of liquid polyamorphism. In this study, we examined the density, dynamic, and thermodynamic anomalies in the vicinity of the liquid-liquid critical point. The boundaries of density, self-diffusion, shear viscosity, and excess entropy anomalies were characterized. Furthermore, these anomalies are connected according to Rosenfeld's scaling relationship between the excess entropy and the transport coefficients such as diffusion and viscosity. The results demonstrate the hierarchical and nested structures regarding the thermodynamic and dynamic anomalies of the Fermi-Jagla model.
A tool for model based diagnostics of the AGS Booster
International Nuclear Information System (INIS)
Luccio, A.
1993-01-01
A model-based algorithmic tool was developed to search for lattice errors by a systematic analysis of orbit data in the AGS Booster synchrotron. The algorithm employs transfer matrices calculated with MAD between points in the ring. Iterative model fitting of the data allows one to find and eventually correct magnet displacements and angles or field errors. The tool, implemented on a HP-Apollo workstation system, has proved very general and of immediate physical interpretation
Static Stiffness Modeling of Parallel Kinematics Machine Tool Joints
O. K. Akmaev; B. A. Enikeev; A. I. Nigmatullin
2015-01-01
The possible variants of an original parallel kinematics machine-tool structure are explored in this article. A new Hooke's universal joint design based on needle roller bearings with the ability of a preload setting is proposed. The bearing stiffness modeling is carried out using a variety of methods. The elastic deformation modeling of a Hook’s joint and a spherical rolling joint have been developed to assess the possibility of using these joints in machine tools with parallel k...
DEFF Research Database (Denmark)
Vrachnos, Ath.; Kontogeorgis, Georgios; Voutsas, EC
2006-01-01
The thermodynamic framework that was developed in a previous work [Vrachnos et al. Ind. Eng. Chem. Res. 2004, 43, 2798] for the description of chemical and vapor-liquid equilibria of carbon dioxide, hydrogen sulfide, and their mixtures in aqueous methyldiethanolamine (MDEA) solutions is revised...... and extended in this study to the absorption of carbon dioxide into aqueous monoethanolamine (MEA) solutions and aqueous MDEA-MEA blends. The results of the model are compared with experimental data taken from the literature. Very satisfactory predictions of acidic gas vapor-liquid equilibrium over MDEA, MEA...
Transparent Model Transformation: Turning Your Favourite Model Editor into a Transformation Tool
DEFF Research Database (Denmark)
Acretoaie, Vlad; Störrle, Harald; Strüber, Daniel
2015-01-01
Current model transformation languages are supported by dedicated editors, often closely coupled to a single execution engine. We introduce Transparent Model Transformation, a paradigm enabling modelers to specify transformations using a familiar tool: their model editor. We also present VMTL, th...... model transformation tool sharing the model editor’s benefits, transparently....
Gray, William G; Miller, Cass T
2009-08-01
This work is the seventh in a series that introduces and employs the thermodynamically constrained averaging theory (TCAT) for modeling flow and transport in multiscale porous medium systems. This paper expands the previous analyses in the series by developing models at a scale where spatial variations within the system are not considered. Thus the time variation of variables averaged over the entire system is modeled in relation to fluxes at the boundary of the system. This implementation of TCAT makes use of conservation equations for mass, momentum, and energy as well as an entropy balance. Additionally, classical irreversible thermodynamics is assumed to hold at the microscale and is averaged to the megascale, or system scale. The fact that the local equilibrium assumption does not apply at the megascale points to the importance of obtaining closure relations that account for the large-scale manifestation of small-scale variations. Example applications built on this foundation are suggested to stimulate future work.
Thermodynamics of adaptive molecular resolution.
Delgado-Buscalioni, R
2016-11-13
A relatively general thermodynamic formalism for adaptive molecular resolution (AMR) is presented. The description is based on the approximation of local thermodynamic equilibrium and considers the alchemic parameter λ as the conjugate variable of the potential energy difference between the atomistic and coarse-grained model Φ=U (1) -U (0) The thermodynamic formalism recovers the relations obtained from statistical mechanics of H-AdResS (Español et al, J. Chem. Phys. 142, 064115, 2015 (doi:10.1063/1.4907006)) and provides relations between the free energy compensation and thermodynamic potentials. Inspired by this thermodynamic analogy, several generalizations of AMR are proposed, such as the exploration of new Maxwell relations and how to treat λ and Φ as 'real' thermodynamic variablesThis article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'. © 2016 The Author(s).
Risk Assessment in Fractured Clayey Tills - Which Modeling Tools?
DEFF Research Database (Denmark)
Chambon, Julie Claire Claudia; Bjerg, Poul Løgstrup; Binning, Philip John
2012-01-01
The article presents different tools available for risk assessment in fractured clayey tills and their advantages and limitations are discussed. Because of the complex processes occurring during contaminant transport through fractured media, the development of simple practical tools for risk...... assessment is challenging and the inclusion of the relevant processes is difficult. Furthermore the lack of long-term monitoring data prevents from verifying the accuracy of the different conceptual models. Further investigations based on long-term data and numerical modeling are needed to accurately...... describe contaminant transport in fractured media and develop practical tools with the relevant processes and level of complexity....
Derivation of the phase field equations from the thermodynamic extremal principle
International Nuclear Information System (INIS)
Svoboda, J.; Fischer, F.D.; McDowell, D.L.
2012-01-01
Thermodynamics employs quantities that characterize the state of the system and provides driving forces for system evolution. These quantities can be applied by means of the thermodynamic extremal principle to obtain models and consequently constitutive equations for the evolution of the thermodynamic systems. The phase field method is a promising tool for simulation of the microstructure evolution in complex systems but introduces several parameters that are not standard in thermodynamics. The purpose of this paper is to show how the phase field method equations can be derived from the thermodynamic extremal principle, allowing the common treatment of the phase field parameters together with standard thermodynamic parameters in future applications. Fixed values of the phase field parameters may, however, not guarantee fixed values of thermodynamic parameters. Conditions are determined, for which relatively stable values of the thermodynamic parameters are guaranteed during phase field method simulations of interface migration. Finally, analytical relations between the thermodynamic and phase field parameters are found and verified for these simulations. A slight dependence of the thermodynamic parameters on the driving force is determined for the cases examined.
Rasp Tool on Phoenix Robotic Arm Model
2008-01-01
This close-up photograph taken at the Payload Interoperability Testbed at the University of Arizona, Tucson, shows the motorized rasp protruding from the bottom of the scoop on the engineering model of NASA's Phoenix Mars Lander's Robotic Arm. The rasp will be placed against the hard Martian surface to cut into the hard material and acquire an icy soil sample for analysis by Phoenix's scientific instruments. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.
Directory of Open Access Journals (Sweden)
Lingen Chen
2012-01-01
Full Text Available A thermodynamic model of an open combined regenerative Brayton and inverse Brayton cycles with regeneration before the inverse cycle is established in this paper by using thermodynamic optimization theory. The flow processes of the working fluid with the pressure drops and the size constraint of the real power plant are modeled. There are 13 flow resistances encountered by the working fluid stream for the cycle model. Four of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining nine flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, regenerator inlet and outlet, combustion chamber inlet and outlet, turbine outlet of the top cycle, turbine outlet of the bottom cycle, heat exchanger inlet, and compressor inlet of the bottom cycle. These resistances associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle, and control the air flow rate, the net power output and the thermal efficiency. The analytical formulae about the power output, efficiency and other coefficients are derived with 13 pressure drop losses. It is found that the combined cycle with regenerator can reach higher thermal efficiency but smaller power output than those of the base combined cycle at small compressor inlet relative pressure drop of the top cycle.
Modeling Tools for Drilling, Reservoir Navigation, and Formation Evaluation
Directory of Open Access Journals (Sweden)
Sushant Dutta
2012-06-01
Full Text Available The oil and gas industry routinely uses borehole tools for measuring or logging rock and fluid properties of geologic formations to locate hydrocarbons and maximize their production. Pore fluids in formations of interest are usually hydrocarbons or water. Resistivity logging is based on the fact that oil and gas have a substantially higher resistivity than water. The first resistivity log was acquired in 1927, and resistivity logging is still the foremost measurement used for drilling and evaluation. However, the acquisition and interpretation of resistivity logging data has grown in complexity over the years. Resistivity logging tools operate in a wide range of frequencies (from DC to GHz and encounter extremely high (several orders of magnitude conductivity contrast between the metal mandrel of the tool and the geologic formation. Typical challenges include arbitrary angles of tool inclination, full tensor electric and magnetic field measurements, and interpretation of complicated anisotropic formation properties. These challenges combine to form some of the most intractable computational electromagnetic problems in the world. Reliable, fast, and convenient numerical modeling of logging tool responses is critical for tool design, sensor optimization, virtual prototyping, and log data inversion. This spectrum of applications necessitates both depth and breadth of modeling software—from blazing fast one-dimensional (1-D modeling codes to advanced threedimensional (3-D modeling software, and from in-house developed codes to commercial modeling packages. In this paper, with the help of several examples, we demonstrate our approach for using different modeling software to address different drilling and evaluation applications. In one example, fast 1-D modeling provides proactive geosteering information from a deep-reading azimuthal propagation resistivity measurement. In the second example, a 3-D model with multiple vertical resistive fractures
Directory of Open Access Journals (Sweden)
Anush Chiappino-Pepe
2017-03-01
Full Text Available Novel antimalarial therapies are urgently needed for the fight against drug-resistant parasites. The metabolism of malaria parasites in infected cells is an attractive source of drug targets but is rather complex. Computational methods can handle this complexity and allow integrative analyses of cell metabolism. In this study, we present a genome-scale metabolic model (iPfa of the deadliest malaria parasite, Plasmodium falciparum, and its thermodynamics-based flux analysis (TFA. Using previous absolute concentration data of the intraerythrocytic parasite, we applied TFA to iPfa and predicted up to 63 essential genes and 26 essential pairs of genes. Of the 63 genes, 35 have been experimentally validated and reported in the literature, and 28 have not been experimentally tested and include previously hypothesized or novel predictions of essential metabolic capabilities. Without metabolomics data, four of the genes would have been incorrectly predicted to be non-essential. TFA also indicated that substrate channeling should exist in two metabolic pathways to ensure the thermodynamic feasibility of the flux. Finally, analysis of the metabolic capabilities of P. falciparum led to the identification of both the minimal nutritional requirements and the genes that can become indispensable upon substrate inaccessibility. This model provides novel insight into the metabolic needs and capabilities of the malaria parasite and highlights metabolites and pathways that should be measured and characterized to identify potential thermodynamic bottlenecks and substrate channeling. The hypotheses presented seek to guide experimental studies to facilitate a better understanding of the parasite metabolism and the identification of targets for more efficient intervention.
Chiappino-Pepe, Anush; Ataman, Meriç
2017-01-01
Novel antimalarial therapies are urgently needed for the fight against drug-resistant parasites. The metabolism of malaria parasites in infected cells is an attractive source of drug targets but is rather complex. Computational methods can handle this complexity and allow integrative analyses of cell metabolism. In this study, we present a genome-scale metabolic model (iPfa) of the deadliest malaria parasite, Plasmodium falciparum, and its thermodynamics-based flux analysis (TFA). Using previous absolute concentration data of the intraerythrocytic parasite, we applied TFA to iPfa and predicted up to 63 essential genes and 26 essential pairs of genes. Of the 63 genes, 35 have been experimentally validated and reported in the literature, and 28 have not been experimentally tested and include previously hypothesized or novel predictions of essential metabolic capabilities. Without metabolomics data, four of the genes would have been incorrectly predicted to be non-essential. TFA also indicated that substrate channeling should exist in two metabolic pathways to ensure the thermodynamic feasibility of the flux. Finally, analysis of the metabolic capabilities of P. falciparum led to the identification of both the minimal nutritional requirements and the genes that can become indispensable upon substrate inaccessibility. This model provides novel insight into the metabolic needs and capabilities of the malaria parasite and highlights metabolites and pathways that should be measured and characterized to identify potential thermodynamic bottlenecks and substrate channeling. The hypotheses presented seek to guide experimental studies to facilitate a better understanding of the parasite metabolism and the identification of targets for more efficient intervention. PMID:28333921
Assanis, D. N.; Ekchian, J. E.; Frank, R. M.; Heywood, J. B.
1985-01-01
A computer simulation of the turbocharged turbocompounded direct-injection diesel engine system was developed in order to study the performance characteristics of the total system as major design parameters and materials are varied. Quasi-steady flow models of the compressor, turbines, manifolds, intercooler, and ducting are coupled with a multicylinder reciprocator diesel model, where each cylinder undergoes the same thermodynamic cycle. The master cylinder model describes the reciprocator intake, compression, combustion and exhaust processes in sufficient detail to define the mass and energy transfers in each subsystem of the total engine system. Appropriate thermal loading models relate the heat flow through critical system components to material properties and design details. From this information, the simulation predicts the performance gains, and assesses the system design trade-offs which would result from the introduction of selected heat transfer reduction materials in key system components, over a range of operating conditions.
Model based methods and tools for process systems engineering
DEFF Research Database (Denmark)
Gani, Rafiqul
Process systems engineering (PSE) provides means to solve a wide range of problems in a systematic and efficient manner. This presentation will give a perspective on model based methods and tools needed to solve a wide range of problems in product-process synthesis-design. These methods and tools...... need to be integrated with work-flows and data-flows for specific product-process synthesis-design problems within a computer-aided framework. The framework therefore should be able to manage knowledge-data, models and the associated methods and tools needed by specific synthesis-design work...... of model based methods and tools within a computer aided framework for product-process synthesis-design will be highlighted....
Thermodynamic Modeling of the SRS Evaporators: Part II. The 3H System
Energy Technology Data Exchange (ETDEWEB)
Jantzen, C.M.
2001-10-02
Accumulations of two solid phases have formed scale deposits in the Savannah River Site 2H Evaporator system since late 1996. The aluminosilicate scale deposits caused the evaporator pot to become inoperable in October 1999. Accumulations of the diuranate phase have caused criticality concerns in the SRS 2H Evaporator. In order to ensure that similar deposits are not and will not form in the SRS 3H Evaporator, thermodynamically derived activity diagrams specific to the feeds processed from Tanks 30 and 32 are evaluated in this report.
Thermodynamic properties of a spin-1 model with long-range interactions
Hou, Ji-Xuan; Yu, Xu-Chen
2018-02-01
The long-range interacting spin-1 chain placed in a staggered magnetic field is studied by means of microcanonical approach. Firstly, we study the microcanonical entropy of the system in the thermodynamic limit and find the system is non-ergodic and can exhibit either first-order phase transition or second-order phase transition by shifting the external magnetic field strength. Secondly, we construct the global phase diagram of the system and find a phase transition area in the phase diagram corresponding to the temperature jump of the first-order phase transition.
Tschiptschin, André Paulo
2002-01-01
Thermodynamic calculations of the Fe-Cr-N System in the region of the Gas Phase Equilibria have been compared with experimental results of maximum nitrogen absorption during nitriding of two Martensitic Stainless Steels (a 6 mm thick sheet of AISI 410S steel and green powder compacts of AISI 434L steel) under N2 atmospheres. The calculations have been performed combining the Fe-Cr-N System description contained in the SGTE Solid Solution Database and the gas phase for the N System contained i...
Pre-Processing and Modeling Tools for Bigdata
Directory of Open Access Journals (Sweden)
Hashem Hadi
2016-09-01
Full Text Available Modeling tools and operators help the user / developer to identify the processing field on the top of the sequence and to send into the computing module only the data related to the requested result. The remaining data is not relevant and it will slow down the processing. The biggest challenge nowadays is to get high quality processing results with a reduced computing time and costs. To do so, we must review the processing sequence, by adding several modeling tools. The existing processing models do not take in consideration this aspect and focus on getting high calculation performances which will increase the computing time and costs. In this paper we provide a study of the main modeling tools for BigData and a new model based on pre-processing.
Directory of Open Access Journals (Sweden)
Anatoliy G. Chernyatevich
2017-10-01
Full Text Available Background. In modern conditions, the BOP-process is the main method of mass use steel product production. At the same time, due to the shortage of high-quality charge materials, resource and energy-saving technologies are particularly relevant. To optimize the BOP-process under modern conditions, it is promising to use improved oxygen lances for top blowing in comparison with known designs. Objective. An important stage in the development of advanced steel production technologies is obtaining information on the thermodynamic model of blowing a converter bath through a three-tier lance with the elaboration of the regularities of oxidation processes within the reaction zone of a 160-ton industrial converter. Methods. The analysis that was carried out has a theoretical nature and is based on the definition of the influence of temperature and pressure on the regularities of oxidation processes within the reaction zones formed when oxygen jets are introduced into the volume of a metal bath, foamed slag-metallic emulsion and waste gases in the working space of the converter. As a thermodynamic parameter, the Gibbs energy was used to estimate the probability of chemical reactions. The pressure effect on the oxidation processes in the converter bath was evaluated in accordance with the Van’t Hoff formula. Results. The thermodynamic features of oxidation processes in the 160-ton BOF bath using a three-tier lance are presented. Primary reaction zone is characterized by the occurrence of oxidation of manganese, silicon, carbon, and iron by gaseous oxygen. In the secondary reaction zone there are chemical reactions of the oxidation of silicon and carbon dissolved in the metal by oxygen, as well as the reduction of iron oxide by carbon. The presence or absence of a slag phase on the melt surface practically does not affect the occurrence probability of chemical transformations within the boundary of primary and secondary reaction zones. The additional
Thermodynamic properties of cryogenic fluids
Leachman, Jacob; Lemmon, Eric; Penoncello, Steven
2017-01-01
This update to a classic reference text provides practising engineers and scientists with accurate thermophysical property data for cryogenic fluids. The equations for fifteen important cryogenic fluids are presented in a basic format, accompanied by pressure-enthalpy and temperature-entropy charts and tables of thermodynamic properties. It begins with a chapter introducing the thermodynamic relations and functional forms for equations of state, and goes on to describe the requirements for thermodynamic property formulations, needed for the complete definition of the thermodynamic properties of a fluid. The core of the book comprises extensive data tables and charts for the most commonly-encountered cryogenic fluids. This new edition sees significant updates to the data presented for air, argon, carbon monoxide, deuterium, ethane, helium, hydrogen, krypton, nitrogen and xenon. The book supports and complements NIST’s REFPROP - an interactive database and tool for the calculation of thermodynamic propertie...
Directory of Open Access Journals (Sweden)
Ying Jiang
2017-02-01
Full Text Available This paper presents a theoretical formalism for describing systems of semiflexible polymers, which can have density variations due to finite compressibility and exhibit an isotropic-nematic transition. The molecular architecture of the semiflexible polymers is described by a continuum wormlike-chain model. The non-bonded interactions are described through a functional of two collective variables, the local density and local segmental orientation tensor. In particular, the functional depends quadratically on local density-variations and includes a Maier–Saupe-type term to deal with the orientational ordering. The specified density-dependence stems from a free energy expansion, where the free energy of an isotropic and homogeneous homopolymer melt at some fixed density serves as a reference state. Using this framework, a self-consistent field theory is developed, which produces a Helmholtz free energy that can be used for the calculation of the thermodynamics of the system. The thermodynamic properties are analysed as functions of the compressibility of the model, for values of the compressibility realizable in mesoscopic simulations with soft interactions and in actual polymeric materials.
Epifano, Enrica; Guéneau, Christine; Belin, Renaud C; Vauchy, Romain; Lebreton, Florent; Richaud, Jean-Christophe; Joly, Alexis; Valot, Christophe; Martin, Philippe M
2017-07-03
In the frame of minor actinide transmutation, americium can be diluted in UO 2 and (U, Pu)O 2 fuels burned in fast neutron reactors. The first mandatory step to foresee the influence of Am on the in-reactor behavior of transmutation targets or fuel is to have fundamental knowledge of the Am-O binary system and, in particular, of the AmO 2-x phase. In this study, we coupled HT-XRD (high-temperature X-ray diffraction) experiments with CALPHAD thermodynamic modeling to provide new insights into the structural properties and phase equilibria in the AmO 2-x -AmO 1.61+x -Am 2 O 3 domain. Because of this approach, we were able for the first time to assess the relationships between temperature, lattice parameter, and hypostoichiometry for fcc AmO 2-x . We showed the presence of a hyperstoichiometric existence domain for the bcc AmO 1.61+x phase and the absence of a miscibility gap in the fcc AmO 2-x phase, contrary to previous representations of the phase diagram. Finally, with the new experimental data, a new CALPHAD thermodynamic model of the Am-O system was developed, and an improved version of the phase diagram is presented.
Directory of Open Access Journals (Sweden)
Enner Herenio de Alcântara
2011-08-01
Full Text Available Aquatic systems continually respond to climatic conditions that vary over broad scales of space and time. The response of each water body to external conditions (hydro-meteorological processes is revealed in the first place by the thermal structures present in water body. Most lacustrine chemical, physical and biological processes are affected directly by lake hydrological (e.g. lake depth and thermal changes (e.g. seasonal stratification, and are thus, indirectly affected by climate variation. Understanding lake-climate system interactions is therefore of fundamental importance to evaluate the effects of climate change on limnological processes. Based on this, the objective of this work was to develop a thermodynamic conceptual model for the Itumbiara hydroelectric reservoir (Goiás State, Brazil. The developed methodology was based on the use of satellite imagery of moderate resolution that allow the computation of the water surface temperature from 2003 to 2008 (six years during the daytime and nighttime. The results showed the potential of the use of moderate resolution satellite data to study water surface temperature variability and to explain the main causes of this variability. The use of hydro-meteorological and bulk temperature collected by station and autonomous buoy, respectively, contributed to better understand the physical processes in the mixed depth of the reservoir. Also the results allow the elaboration of conceptual models for the thermodynamics of the Itumbiara reservoir.
Shu, Min; Zhu, Liang; Wang, Yan-fei; Yang, Jing; Wang, Liyu; Yang, Libin; Zhao, Xiaoyu; Du, Wei
2018-01-01
The solubility and dissolution thermodynamic properties of raspberry ketone in a set of binary solvent mixtures (ethanol + water) with different compositions were experimentally determined by static gravimetrical method in the temperature range of 283.15-313.15 K at 0.10 MPa. The solubility of raspberry ketone in this series of ethanol/water binary solvent mixtures was found to increase with a rise in temperature and the rising mole fraction of ethanol in binary solvent mixtures. The van't Hoff, modified Apelblat and 3D Jouyban-Acree-van't Hoff equations were increasingly applied to correlate the solubility in ethanol/water binary solvent mixtures. The former two models could reach better fitting results with the solubility data, while the 3D model can be comprehensively used to estimate the solubility data in all the ratios of ethanol and water in binary solvent mixtures at random temperature. Furthermore, the changes of dissolution thermodynamic properties of raspberry ketone in experimental ethanol/water solvent mixtures were obtained by van't Hoff equation. For all the above experiments, these dissolution processes of raspberry ketone in experimental ethanol/water binary solvent mixtures were estimated to be endothermic and enthalpy-driven.
Energy Technology Data Exchange (ETDEWEB)
Fuertauer, Siegfried; Beutl, Alexander; Flanorfer, Hans [Vienna Univ. (Austria). Dept. of Inorganic Chemistry - Functional Materials; Li, Dajian; Cupid, Damian [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). Inst. for Applied Materials - Applied Materials Physics (IAM-AWP); Henriques, David; Giel, Hans; Markus, Thorsten [Mannheim Univ. of Applied Sciences (Germany). Inst. for Thermo- and Fluiddynamics
2017-11-15
This article reports on two consecutive joint projects titled ''Experimental Thermodynamics and Phase Relations of New Electrode Materials for Lithium-Ion Batteries'', which were performed in the framework of the WenDeLIB 1473 priority program ''Materials with new Design for Lithium Ion Batteries''. Hundreds of samples were synthesized using experimental techniques specifically developed to deal with highly reactive lithium and lithium-containing compounds to generate electrochemical, phase diagram and crystal structure data in the Cu-Li, Li-Sn, Li-Sb, Cu-Li-Sn, Cu-Li-Sb and selected oxide systems. The thermochemical and phase diagram data were subsequently used to develop self-consistent thermodynamic descriptions of several binary systems. In the present contribution, the experimental techniques, working procedures, results and their relevance to the development of new electrode materials for lithium ion batteries are discussed and summarized. The collaboration between the three groups has resulted in more than fifteen (15) published articles during the six-year funding period.
International Nuclear Information System (INIS)
Zhao, H; Aluru, N R
2007-01-01
This paper presents a semi-local quasi-harmonic model with local phonon density of states (LPDOS) to compute the thermodynamic and mechanical properties of silicon nanostructures at finite temperature. In contrast to an earlier approach (Tang and Aluru 2006 Phys. Rev. B 74 235441), where a quasi-harmonic model with LPDOS computed by a Green's function technique (QHMG) was developed considering many layers of atoms, the semi-local approach considers only two layers of atoms to compute the LPDOS. We show that the semi-local approach combines the accuracy of the QHMG approach and the computational efficiency of the local quasi-harmonic model. We present results for several silicon nanostructures to address the accuracy and efficiency of the semi-local approach
Designer Modeling for Personalized Game Content Creation Tools
DEFF Research Database (Denmark)
Liapis, Antonios; Yannakakis, Georgios N.; Togelius, Julian
2013-01-01
With the growing use of automated content creation and computer-aided design tools in game development, there is potential for enhancing the design process through personalized interactions between the software and the game developer. This paper proposes designer modeling for capturing the designer......’s preferences, goals and processes from their interaction with a computer-aided design tool, and suggests methods and domains within game development where such a model can be applied. We describe how designer modeling could be integrated with current work on automated and mixed-initiative content creation...
Fish habitat simulation models and integrated assessment tools
International Nuclear Information System (INIS)
Harby, A.; Alfredsen, K.
1999-01-01
Because of human development water use increases in importance, and this worldwide trend is leading to an increasing number of user conflicts with a strong need for assessment tools to measure the impacts both on the ecosystem and the different users and user groups. The quantitative tools must allow a comparison of alternatives, different user groups, etc., and the tools must be integrated while impact assessments includes different disciplines. Fish species, especially young ones, are indicators of the environmental state of a riverine system and monitoring them is a way to follow environmental changes. The direct and indirect impacts on the ecosystem itself are measured, and impacts on user groups is not included. Fish habitat simulation models are concentrated on, and methods and examples are considered from Norway. Some ideas on integrated modelling tools for impact assessment studies are included. One dimensional hydraulic models are rapidly calibrated and do not require any expert knowledge in hydraulics. Two and three dimensional models require a bit more skilled users, especially if the topography is very heterogeneous. The advantages of using two and three dimensional models include: they do not need any calibration, just validation; they are predictive; and they can be more cost effective than traditional habitat hydraulic models when combined with modern data acquisition systems and tailored in a multi-disciplinary study. Suitable modelling model choice should be based on available data and possible data acquisition, available manpower, computer, and software resources, and needed output and accuracy in the output. 58 refs
Simulation Tools for Electrical Machines Modelling: Teaching and ...
African Journals Online (AJOL)
Simulation tools are used both for research and teaching to allow a good comprehension of the systems under study before practical implementations. This paper illustrates the way MATLAB is used to model non-linearites in synchronous machine. The machine is modeled in rotor reference frame with currents as state ...
Advanced REACH Tool (ART) : Calibration of the mechanistic model
Schinkel, J.; Warren, N.; Fransman, W.; Tongeren, M. van; McDonnell, P.; Voogd, E.; Cherrie, J.W.; Tischer, M.; Kromhout, H.; Tielemans, E.
2011-01-01
The mechanistic model of the Advanced Reach Tool (ART) provides a relative ranking of exposure levels from different scenarios. The objectives of the calibration described in this paper are threefold: to study whether the mechanistic model scores are accurately ranked in relation to exposure
Molecular Modeling: A Powerful Tool for Drug Design and Molecular ...
Indian Academy of Sciences (India)
Molecular modeling has become a valuable and essential tool to medicinal chemists in the drug design process. Molecular modeling describes the generation, manipula- tion or representation of three-dimensional structures of molecules and associated physico-chemical properties. It involves a range of computerized ...
Energy Technology Data Exchange (ETDEWEB)
S. Dartevelle
2005-09-05
The objective of this manuscript is to fully derive a geophysical multiphase model able to ''accommodate'' different multiphase turbulence approaches; viz., the Reynolds Averaged Navier-Stokes (RANS), the Large Eddy Simulation (LES), or hybrid RANSLES. This manuscript is the first part of a larger geophysical multiphase project--lead by LANL--that aims to develop comprehensive modeling tools for large-scale, atmospheric, transient-buoyancy dusty jets and plume (e.g., plinian clouds, nuclear ''mushrooms'', ''supercell'' forest fire plumes) and for boundary-dominated geophysical multiphase gravity currents (e.g., dusty surges, diluted pyroclastic flows, dusty gravity currents in street canyons). LES is a partially deterministic approach constructed on either a spatial- or a temporal-separation between the large and small scales of the flow, whereas RANS is an entirely probabilistic approach constructed on a statistical separation between an ensemble-averaged mean and higher-order statistical moments (the so-called ''fluctuating parts''). Within this specific multiphase context, both turbulence approaches are built up upon the same phasic binary-valued ''function of presence''. This function of presence formally describes the occurrence--or not--of any phase at a given position and time and, therefore, allows to derive the same basic multiphase Navier-Stokes model for either the RANS or the LES frameworks. The only differences between these turbulence frameworks are the closures for the various ''turbulence'' terms involving the unknown variables from the fluctuating (RANS) or from the subgrid (LES) parts. Even though the hydrodynamic and thermodynamic models for RANS and LES have the same set of Partial Differential Equations, the physical interpretations of these PDEs cannot be the same, i.e., RANS models an averaged field, while LES simulates a
Schrödinger, Erwin
1952-01-01
Nobel Laureate's brilliant attempt to develop a simple, unified standard method of dealing with all cases of statistical thermodynamics - classical, quantum, Bose-Einstein, Fermi-Dirac, and more.The work also includes discussions of Nernst theorem, Planck's oscillator, fluctuations, the n-particle problem, problem of radiation, much more.
Ada, Kezban; Ergene, Aysun; Tan, Sema; Yalçin, Emine
2009-06-15
Zinc oxide powders with six-sided flake-like particles were prepared by homogeneous precipitation from boiling aqueous solutions that contained excess urea and 0.075 (Z075) and 0.300 (Z300)M Zn(2+). The average sizes of the particles are 37 and 46 microm, while the average sizes of the crystals are approximately 45 for Z075 and Z300 at 1000 degrees C. Equilibrium, kinetic and thermodynamic studies were carried out for the adsorption of RBBR dye from aqueous solution using both types of ZnO in the form of fine powders. The effects of pH, initial dye concentration, contact time and temperature of solution on the adsorption were studied. Langmuir, Temkin and Dubinin-Radushkevich (D-R) isotherm models were used to describe the adsorption of RBBR onto ZnO powders. The Langmuir and D-R isotherm models fit the equilibrium data better than the Temkin isotherm model. The monomolecular adsorption capacity of Z075 and Z300 was determined to be 190 and 345 mg g(-1) for RBBR, respectively. The Lagergren first-order, Ritchie second-order kinetic and intra-particle diffusion models were used for the adsorption of the dye onto ZnO powders. The Ritchie second-order model was suitable for describing the adsorption kinetics for the removal of RBBR from aqueous solution onto Z075 and Z300. Thermodynamic parameters, such as the Gibbs free energy (DeltaG(#)), enthalpy (DeltaH(#)), entropy (DeltaS(#)) and equilibrium constant of activation (K(#)) were calculated. These parameters showed that the adsorption process of RBBR onto Z075 and Z300 was an endothermic process of a chemical nature under the studied conditions.
Business intelligence tools for radiology: creating a prototype model using open-source tools.
Prevedello, Luciano M; Andriole, Katherine P; Hanson, Richard; Kelly, Pauline; Khorasani, Ramin
2010-04-01
Digital radiology departments could benefit from the ability to integrate and visualize data (e.g. information reflecting complex workflow states) from all of their imaging and information management systems in one composite presentation view. Leveraging data warehousing tools developed in the business world may be one way to achieve this capability. In total, the concept of managing the information available in this data repository is known as Business Intelligence or BI. This paper describes the concepts used in Business Intelligence, their importance to modern Radiology, and the steps used in the creation of a prototype model of a data warehouse for BI using open-source tools.
Geometric Model of Black Hole Quantum N-portrait, Extradimensions and Thermodynamics
Directory of Open Access Journals (Sweden)
Antonia M. Frassino
2016-05-01
Full Text Available Recently a short scale modified black hole metric, known as holographic metric, has been proposed in order to capture the self-complete character of gravity. In this paper we show that such a metric can reproduce some geometric features expected from the quantum N-portrait beyond the semi-classical limit. We show that for a generic N this corresponds to having an effective energy momentum tensor in Einstein equations or, equivalently, non-local terms in the gravity action. We also consider the higher dimensional extension of the metric and the case of an AdS cosmological term. We provide a detailed thermodynamic analysis of both cases, with particular reference to the repercussions on the Hawking-Page phase transition.
Bembel, A. G.
2017-02-01
Size dependences of the nanocrystal sublimation and the evaporation heats of the corresponding nanodrops are investigated using the isothermal molecular dynamics and the tight-binding potential (on examples of Ni and Au nanoparticles). Results of computer simulation demonstrating linear dependences of the evaporation and sublimation heats on the particle reciprocal radius are compared with results of thermodynamic calculations as well as with experimental data for bulk phases of the same metals. It has been found that the size dependences of the evaporation and sublimation heats are directly related with the behavior of the size dependence of the melting heat that in its turn correlates with structural transformations in nanoparticles induced by the change of their size. The conclusion is drawn that there is some characteristic nanoparticle size (of the order of 1 nm) at which its crystal and liquid states become indistinguishable.
Effect of the vitamin D photosynthesis products on thermodynamic parameters of model lipid membranes
Directory of Open Access Journals (Sweden)
Lisetski L. N.
2012-04-01
Full Text Available Aim. To compare effects of vitamin D (VitD, provitamin D (ProD and its photo- and thermoisomerization products on thermodynamical parameters of hydrated dipalmitoylphoshpatidylcholine (DPPC multilayers. Methods. Differential scanning calorimetry, UV spectroscopy. Results. A regular decrease was established in the melting temperature accompanied with the pronounced broadening of the appropriate peaks for DPPC multilayers doped with the sterols in the order ProD3 < < ProD3 + UV < ProD3 + UV + dark storage < VitD3. Conclusions. The destabilizing effect of VitD3 on the membrane appeared to be stronger than that of ProD3 and its photoisomerization products. This can facilitate VitD3 withdrawal from the membrane into intercellular space under its biosinthesis in vivo. A possible molecular mechanism of the phenomena observed is related to the higher conformational flexibility and anisometry of VitD3 as compared to ProD3.
Thermal Behavior of Cd During Sludge Incineration: Experiments and Thermodynamic Equilibrium Model.
Liu, Jingyong; Zhuo, Zhongxu; Sun, Shuiyu; Xie, Wuming; Lu, Shaoyou; Sun, Jian; Kuo, Jiahong; Yujie, Wang
2016-12-01
Experiments and thermodynamic equilibrium calculations were performed to investigate the behavior of Cd during sewage sludge incineration. The chemical equilibrium calculations indicated that chlorine significantly increased the volatilization of Cd in the form of CdCl2. In addition, SiO2-containing materials can function as sorbents for stabilizing Cd. The effect of PVC added to the sludge on the migration of Cd in the sludge was greater than that of NaCl. As the temperature increased, both organic and inorganic chlorides reduced the Cd distribution in the bottom ash. The chloride concentration, and the incineration time exhibited insignificant changes in Cd emission. With the addition of either NaCl or PVC into the sludge, the phases of Cd present in the bottom slag were primarily present in the form of silica-alumina oxides or multi-metal oxide, which could inhabit the Cd volatilization.
Sohrab, Siavash
2016-03-01
A scale-invariant model of statistical mechanics is applied to described modified forms of four laws of classical thermodynamics. Following de Broglie formula λrk = h /mkvrk , frequency of matter waves is defined as νrk = k /mkvrk leading to stochastic definitions of (Planck, Boltzmann) universal constants (h =mk c , k =mk c), λrkνrk = c , relating to spatiotemporal Casimir vacuum fluctuations. Invariant Mach number Maβ = v /vrβ is introduced leading to hierarchy of ``supersonic'' flow separated by shock front, viewed as ``event-horizon'' EHβ, from subsonic flow that terminates at surface of stagnant condensate of ``atoms'' defined as ``black-hole'' BHβ at scale β thus resulting in hierarchy of embedded ``black holes'' at molecular- atomic-, electron-, photon-, tachyon-. . . scales, ad infinitum. Classical black hole will correspond to solid phase photon or solid-light. It is argued that Bardeen-Carter-Hawking (1973) first law of black hole mechanics δM = (κ / 8 π) δA +ΩH δJ +ΦH δQ , instead of dE = TdS - PdV suggested by Bekenstein (1973), is analogous to first law of thermodynamics expressed as TdS = PdV + dE such that entropy of black hole, rather than to its horizon surface area, will be related to its total energy hence enthalpy H = TS leading to SBH = 4 kN in exact agreement with prediction of Major and Setter.
Thermodynamic and Modeling Study of Cyclopentane on MgO (100), hBN and Graphite Basal Plane
Wahida, Fatema; Strange, Nicholas; Larese, John Z.
Investigation of the adsorption of cyclopentane on magnesium oxide (100), hexagonal boron nitride and the graphite basal plane was undertaken to explore the role of surface symmetry on the physicochemical properties. This is one portion of a broader study of 2D layers of cyclic organic molecules adsorbed on these scientifically and industrially important substrates. A series of high-resolution volumetric adsorption isotherms over the temperature range of 195-265K were measured on each of the substrates and used to calculate such thermodynamic properties as the heat of adsorption and isosteric heat, differential enthalpy, and differential entropy of adsorption during the layer growth process. The behavior of the two dimensional isothermal compressibility as a function of temperature and coverage was used to identify the locations of layering and potential phase transitions. To gain additional insight into the microscopic details of the adsorption process, classical molecular dynamics simulations were performed using a centralized force field (COMPASS) in tandem with thermodynamic experiments. The results of these modeling studies will be used to aid future quasi- and inelastic neutron scattering experiments aimed at exploring the rotational and translational diffusion and vibrational motion of the single and multilayer molecular films.