Page 1. Computational Chemistry-Based Enthalpy-of-Formation, Enthalpy-of-Vaporization, and Enthalpy-of-Sublimation ...

... Title : Computational Chemistry-Based Enthalpy-of-Formation, Enthalpy-of ... Subject Categories : INORGANIC CHEMISTRY THERMODYNAMICS. ...

The gas phase enthalpies of formation of mono-, di-, tri-, tetranitromethane and nitroethane, as well as of their nitrite and aci-form isomers were calculated using different multilevel (G2, G3, G2M(CC5)) and density functional theory (DFT)-based (B3LYP, MPW1B95 and MPWB1K) techniques. The enthalpies of the C-N bond dissociation and isomerization of these ...

A review of the available methods for computing liquid/vapor phase equilibria for enthalpy deviations via equations of state includes information on the interaction parameters for over 140 binary mixtures, as well as an extension of the Lee-Kesler equation of state that permits the more accurate calculation of important thermodynamic ...

The standard (p(0) = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, of five aminomethoxybenzoic acids, at T = 298.15 K, were derived from the standard molar energies of combustion in oxygen, measured by static-bomb combustion calorimetry. Combining these results with literature results of the standard molar enthalpies of sublimation, at ...

... COMPUTER PROGRAMS, THERMODYNAMICS, SPECIFIC HEAT, ENTHALPY, ENTROPY, HEAT OF FORMATION, HEAT OF COMBUSTION ...

Sep 3, 2010 ... We propose the development of a high fidelity computational approach for unsteady ... high-enthalpy (flow - thermodynamics coupling) and ...

The derivatives of 1,4-benzodioxan are found widely spread in nature and have great biomedical importance. The present work reports an experimental and computational study on the thermochemistry of 1,4-benzodioxan and several of its 6-R derivatives in the gaseous phase, at T = 298.15 K. Our current results were obtained from measurements of combustion energies, at T = 298.15 ...

The applicability of semi-empirical models for estimating the gas-phase enthalpies-of-formation deltafHog (298), enthalpies-of-vaporization deltaHv (298)), and enthalpies-of-sublimation deltaHs, (298)) of azide- functionalized compounds was evaluated. The...

Biofuels composed by fatty acid methyl esters are widely used as partly substituting fuels for diesel fossil fuels. Additionally, it is expected that the diesel biofuel norms will be extended to ethyl esters produced from bioethanol in the upcoming years. A precise knowledge of the standard enthalpy of formation is necessary for the calculation of some parameters useful for ...

... Descriptors : *THERMODYNAMICS, *COMPRESSED AIR, COMPUTER PROGRAMMING, PHYSICAL PROPERTIES, ENTROPY, ENTHALPY ...

Various highly accurate ab initio composite methods of Gaussian-n (G1, G2, G3), their variations (G2(MP2), G3(MP2), G3//B3LYP, G3(MP2)//B3LYP), and complete basis set (CBS-Q, CBS-Q//B3LYP) series of models were applied to compute reaction enthalpies of the ground-state reaction of CO2 with Mg. All model chemistries predict highly ...

... Gibbs free-enthalpy function to generate these thermodynamic properties over ... the computer program is outlined, and the computational results are ...

Polynomial expressions are developed that correlate experimental vapor-liquid-equilibrium (VLE) and specific enthalpy concentration data for a newly developed ternary absorption fluid (LiNO/sub 3/-KNO/sub 3/-NaNO/sub 3/). The development of these expressions are an important step toward using existing ORNL computer software to evaluate heat pump ...

The enthalpy of a fluid measured with respect to some reference temperature and pressure (enthalpy increment or Cp) is required for many engineering designs. Different techniques for determining enthalpy increments include direct measurement, integration of heat capacity as a function of temperature at constant pressure, and ...

Relations were developed that allow easy and accurate calculation of enthalpy changes during the heating, retorting, or cooling of raw, spent, or burned Eastern oil shales. The heat capacities of the mineral matter, bound water, kerogen, and char, and the...

Standard approximations to the density functional theory exchange-correlation functional have been extraordinary successful, but calculating formation enthalpies of reactions involving compounds with both localized and delocalized electronic states remains challenging. In this work we examine the shortcomings of the generalized gradient approximation (GGA) and GGA+U in ...

The purpose of this work was to evaluate the accuracy of the CHIH(medium) DFT model chemistry (PBEg/CBSB2??//PBEg/CBSB4) in the determination of the optimized structure and thermochemical properties of heterocyclic systems of medium size such as flavonoids, wherefore were selected three of the most abundant flavonoids in vegetable tissues, and which posses the higher antioxidant activity: ...

Reductions in heat loss at appropriate points in the diesel engine which result in substantially increased exhaust enthalpy were shown. The concepts for this increased enthalpy are the turbocharged, turbocompounded diesel engine cycle. A computer simulati...

... Descriptors : (*Nuclear propulsion, Reactor fuels), (*Reactor fuels, Vaporization), Enthalpy, Uranium, Carbon, Refractory metals, Computer ...

... NOZZLES, NOZZLE GAS FLOW, ENTHALPY, ABLATION, EROSIVE BURNING, MATHEMATICAL MODELS, FLOW CHARTING, COMPUTER ...

... solubility enhancement, and the solute's partial molar volume and enthalpy are large and negative, diverging to - -o at the solvent's critical point in ...

... The interaction between combined ground test measurements and CFD modeling is considered as genesis for catalytic effects duplication, plasma ...

Ab initio calculations have been performed at the SCF level in the STO-3G, 3-21G, and 6-31G* basis sets on a variety of benzenoid and nonbenzenoid aromatic hydrocarbons, ranging from benzene to coronene. It is shown that (1) the enthalpy changes for homodesmic reactions involving only benzenoid aromatics can be computed accurately in ...

We compare temperature-based and enthalpy-based numerical schemes for compressible non-isothermal subsurface fluid flow. We formulate a diffusion equation for the fluid pressure, a diffusion equation for heat conduction, and an equation for the advective transport of temperature or enthalpy in the fluid. These equations can readily be solved by a ...

Ionic liquids and molten salts are being considered for many novel applications including for use as heat transfer fluids in thermal energy generation cycles. Thermodynamic and transport properties like melting points, heat capacities, viscosities and thermal conductvities were computed for some ionic liquids and molten salts. Melting points were computed ...

The objective of our research has been to develop computational methods that have the capability of accurately predicting equilibrium constants of typical organic reactions in gas and liquid solution phases. We have chosen Diels-Alder reactions as prototypic systems for the investigation, chiefly because there are an adequate number of reported equilibrium ...

The objective of our research has been to develop computational methods that have the capability of accurately predicting equilibrium constants of typical organic reactions in gas and liquid solution phases. We have chosen Diels-Alder reactions as prototypic systems for the investigation, chiefly because there are an adequate number of reported equilibrium ...

The shelf life of mushrooms is very limited since they are susceptible to physical and microbial attack; therefore they are usually blanched and immediately frozen for commercial purposes. The aim of this work was to develop a numerical model using the finite element technique to predict freezing times of mushrooms considering the actual shape of the product. The original heat transfer equation ...

The enthalpy diffusion flux in the multicomponent energy equation is a well known yet frequently neglected term. It accounts for energy changes, associated with compositional changes, resulting from species diffusion. Enthalpy diffusion is important in flows where significant mixing occurs between species of dissimilar molecular weight. The term plays a ...

The classic, conventional analysis for the thermal performance of heat exchangers is based on three assumptions: constant fluid flow rate, constant specific heat fluids, and constant overall heat transfer coefficient. Our analysis describes a general approach for analyzing the thermal performance of heat exchangers in which the overall heat transfer coefficient varies as a function of ...

May 31, 2011 ... A computer program is described which (1) calculates thermodynamic functions ( heat capacity, enthalpy, entropy, and free energy) for several ...

The report lists molecular weights, enthalpies of formation, and associated uncertainties for halogen compounds of hydrogen, oxygen, rare gases, and other halogens, and corresponding hydrates. It also contains enthalpies of reactions of these compounds.

This work describes the extension of a previously reported empirical localized orbital correction model for density functional theory (DFT-LOC) for atomization energies, ionization potentials, electron affinities, and reaction enthalpies to the correction of barrier heights for chemical reactions of various types including cycloadditions, cycloreversions, dipolar ...

In organic chemistry, cyclopropane (C_3H_6) is a highly-strained three-membered carbon ring which can be networked to form [n]triangulanes, which are branched hydrocarbons consisting entirely of spiroannulated cyclopropyl groups. The C_2v-symmetric branched [15]triangulane (C_31H_34) have been recently synthesized (M. von Seebach, S. I. Kozhushkov, R. Boese, J. Benet-Buchholz, D. S. Yufit, J. A. ...

Binding energies including valence-shell electron correlation are obtained from many-body perturbation theory (MBPT) for diborane, borane carbonyl, and borazane. Results are given for basis sets of double zeta quality and for basis sets with polarization functions added on all atoms. The binding energies (-..delta..E) are found to be (respectively) 35, 21, and 30 kcal/mol. Correlation effects ...

A set of correlations for the volumetric properties and enthalpies of phases in the system H2O NaCl as a function of temperature, pressure, and composition has been developed that yields accurate values from 0 to 1000 �C, 1 to 5000 bar, and 0 to 1 XNaCl. The volumetric properties of all fluid phases from low-density vapor to hydrous salt melts and ...

Enthalpies of saturated liquid mixtures are evaluated by combining: (1) the ideal gas state (zero pressure) enthalpy with (2) the isothermal pressure-effect, both being evaluated for the dew-point mixture at the equilibrium temperature. Enthalpies of saturated liquid mixtures can also be computed by combining a ...

ion versus a totally unfolded or non-hybridized state. In the case of hybridization, the target is assumed to be the reverse complement, with possibly a few mismatches allowed, so that no computation is needed to determine the hybridized state. In some cases, melting temperatures are estimated by using ad hoc methods based on GC content. We have undertaken a research program ...

Growing demands on the quality of thermally sprayed coatings require reliable methods to monitor and optimize the spraying processes. Thus, the importance of diagnostic methods is increasing. A critical requirement of diagnostic methods in thermal spray is the accurate measurement of temperatures. This refers to the hot working gases as well as to the in-flight temperature of ...

Growing demands on the quality of thermally sprayed coatings require reliable methods to monitor and optimize the spraying processes. Thus, the importance of diagnostic methods is increasing. A critical requirement of diagnostic methods in thermal spray is the accurate measurement of temperatures. This refers to the hot working gases as well as to the in-flight temperature of ...

The modified Rackett equation represents a simple and very widely used method to predict saturated liquid volumes. In addition to being fairly accurate, this equation is mathematically continuous and renders expressions for first and second derivatives of saturated liquid volume needed for computations of thermodynamic properties such as ...

Geothermal well performances depend primarily on four factors: reservoir pressure, permeability, temperature and wellbore size. The ability to predict both the quantity of fluid that can be produced and its thermodynamic state (pressure, temperature, enthalpy, gas content, salinity, etc.) is essential for estimating the total usable energy of a geothermal resource. Numerical ...

Ionic ligands can bind to polyelectrolytes such as DNA or charged polysaccharides. We develop a Poisson-Boltzmann treatment to compute binding constants as a function of ligand charge and salt concentration in the limit of low ligand concentration. For flexible chain ligands, such as oligopeptides, we treat their conformations using lattice statistics. The theory predicts the ...

Differences in O-H bond dissociation enthalpies (?BDEs) between the hydroxylamine of (15)N-labeled TEMPONE and 10 N,N-di-tert-alkyl hydroxylamines were determined by EPR. These ?BDEs, together with the g and a(N) values of the derived nitroxide radicals, are discussed in relation to various geometric, intramolecular dipole/dipole, and steric effects and in relation to the ...

Page 1. EFFICIENT AND ACCURATE COMPUTATION OF NON-NEGATIVE ANISOTROPIC SCATTERING CROSS SECTIONS ...

The standard (p� = 0.1 MPa) molar enthalpy of formation for solid benzanilide was derived from the standard molar enthalpy of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry, and the standard molar enthalpy of sublimation, at T = 298.15 K, measured by Calvet microcalorimetry. From these ...

Binding affinity prediction is one of the most critical components to computer-aided structure-based drug design. Despite advances in first-principle methods for predicting binding affinity, empirical scoring functions that are fast and only relatively accurate are still widely used in structure-based drug design. With the increasing availability of X-ray ...

The standard (p(o) = 0.1 MPa) molar energies of combustion in oxygen, at T = 298.15 K, of solid 3,3-tetramethyleneglutaric acid and the related 3,3-tetramethyleneglutaric anhydride and 3,3-tetramethyleneglutarimide were measured by static bomb combustion calorimetry. The values of the standard molar enthalpies of sublimation, at T = 298.15 K, were obtained by Calvet ...

Despite their importance in many chemical processes, the relative energies of spin states of transition metal complexes have so far been haunted by large computational errors. By the use of six functionals, B3LYP, BP86, TPSS, TPSSh, M06, and M06L, this work studies nine complexes (seven with iron and two with cobalt) for which experimental enthalpies of ...

The accurate estimation of S-O bond dissociation enthalpies (BDE) of sulfoxides by computational chemistry methods has been a significant challenge. One of the primary causes for this challenge is the well-established requirement of including high-exponent d functions in the sulfur basis set for accurate energies. ...

Following up on our earlier developments, we have recently improved (a) our model of the system H2O- NaCl to describe accurately the phase relations [1], volumetric properties, enthalpies and heat capacities [2] now to 1000�C, 500 MPa, and 0 to 100% NaCl, and (b) algorithms for multiphase fluid flow in this system. The fluid properties are formulated ...

The standard molar enthalpies of formation of the 3-methyl-N-R-2-quinoxalinecarboxamide-1,4-dioxides (R = H, phenyl, 2-tolyl) in the gas phase were derived using the values for the enthalpies of combustion of the crystalline compounds, measured by static bomb combustion calorimetry, and for the enthalpies of sublimation, measured by ...

... 4. The activation enthalpy for kink pairs in potassium ... The LIP energy between two atoms at a ... tively simple sum over all configurational energies. ...

... change in heat transfer coef- ficient and recovery enthalpy with variation ... the best' performance because of it's larger heat capacity and conductivity. ...

... Heat flux chart and experimental datafor the subsonic test ... simple gases, or we have to introduce some ... quartz-based materials in dissociated air. ...

Jul 5, 2007 ... Abstract: A computer program is described which (1) calculates thermodynamic functions (heat capacity, enthalpy, entropy, and free energy) ...

they are treated as a source of enthalpy and atoms only. ... Sixteen propellant combinations involving carbon, fluorine, and hydrogen gave the TDK computer ...

Jun 16, 2011 ... Description: Enthalpies of reaction for the initial steps in the pyrolysis of lignin have been evaluated at the CBS-4m level of theory using fully ...

... will calculate the dry-bulb temperature, wet-bulb temperature, dew point, enthalpy, relative humidity, humidity ratio, specific volume, and viscosity. ...

Enthalpy arrays enable label-free, solution-based calorimetric detection of molecular interactions in a 96-detector array format. Compared with conventional calorimetry, enthalpy arrays achieve a significant reduction of sample volume and measurement time through the combination of the small size of the detectors and ability to perform measurements in ...

This study investigates the applications of computational approaches in the prediction of enthalpies of formation (?H(f) ) for C-, H-, and O-containing compounds. Molecular mechanics (MM4) molecular mechanics method, density functional theory (DFT) combined with the atomic equivalent (AE) and group equivalent (GE) schemes, and DFT-based correlation ...

The standard enthalpy of formation of the 2-amino-3-quinoxalinecarbonitrile-1,4-dioxide compound in the gas-phase was derived from the enthalpies of combustion of the crystalline solid measured by static bomb combustion calorimetry and its enthalpy of sublimation determined by Knudsen mass-loss effusion at T= 298.15 K. This value is ...

Based on the finite difference method and the enthalpy model of Shamsundar, a computer model was developed to describe the steady state, two-dimensional heat flow during the welding of thin plates. In order to allow accurate computations of the weld pool configuration, the size of the mushy zone and the temperature ...

Thermodynamic data on nitrogen compounds from numerous sources were stored, sorted and processed by computer. Enthalpies of reactions and formations were determined by the computer from the available data by a least squares procedure. (Modified author abs...

The main goal of this work is to solve the steady Euler equations governing inviscid compressible fluid flow as cleanly and accurately as possible, focusing on the limiting cases where the physical behavior of the flow changes. Incompressible flow, where either the free stream Mach number or the local Mach number approach zero, and potential flow which is appropriate to shock- ...

The first explicitly calculated G3(MP2) enthalpies and Gibbs energies of formation for undecane through eicosane are presented. These values, when corrected for the presence of multiple conformations, are found to be within 4 and often 2 kJ/mol of the experimental values. The derivation of the corrections for the enthalpies, which differ from those of the ...

State-of-the-art, calibrated ab initio quantum chemical calculations have been performed to obtain accurate structures, energies, and vibrational frequencies of the lowest singlet states of HNS and NSH, which are closed-shell states. Enthalpies of formati...

Multiconfigurational quantum chemical methods (CASSCF/CASPT2) have been used to study the chemiionization reactions Ce + O ? CeO+ + e- and Ce + O2 ? CeO 2+ + e-. Selected spectroscopic constants for CeOn and CeO n+ (n = 1, 2), as well as reaction enthalpies of the chemiionization reactions of interest, have been computed and compared with experimental ...

Accurate computation of sensitivity derivatives is becoming an important item in Computational Fluid

In the present manuscript describing traditional, macroscopic thermochemical properties, the authors` language will be that of molecular structure. Enthalpies (or heats of formation) are the subject of this article, and since the most important practical application of enthalpies is to explore reactivities and/or equilibria, they take a kineticist`s ...

A computer program entitled ''WELLFLOW'' is presented for calculating wellhead flow and fluid conditions for a self-flowing geothermal well of constant diameter. The calculational model was developed by Elliott and has been modified to incorporate a more accurate analytical procedure for calculating brine thermophysical ...

This study compares two techniques for uncertainty quantification in chemistry computations, one based on sensitivity analysis and error propagation, and the other on stochastic analysis using polynomial chaos techniques. The two constructions are studied in the context of H{sub 2}-O{sub 2} ignition under supercritical-water conditions. They are compared in terms of their ...

A comparison of the accuracy of several techniques recently developed for solving stiff differential equations is presented. The techniques examined include two general purpose codes EEPISODE and LSODE developed for an arbitrary system of ordinary differential equations, and three specialized codes CHEMEQ, CREKID, and GCKP84 developed specifically to solve chemical kinetic rate equations. The ...

An LES was carried out to clarify the mechanism of decaying swirl in a rod-bundle. In our LES, an immersed boundary method was used to treat this complex wall boundary in the Cartesian grid system. A consistent immersed boundary method and a one-equation dynamic SGS model were introduced for an accurate simulation of no-slip wall condition. The Reynolds number based on the ...

Thermodynamic properties of phosphorus-containing compounds were investigated using high-level ab initio computations. An extended set of contemporary density functional theory (DFT) procedures was assessed for their ability to accurately predict bond dissociation energies of a set of phosphoranyl radicals. The results of meta- and double-hybrids as well ...

Porphyrins are much studied due to their biochemical relevance and many applications. The density functional TPSSh has previously accurately described the energy of close-lying electronic states of transition metal systems such as porphyrins. However, a recent study questioned this conclusion based on calculations of five iron(III) porphines. Here, we ...

A two-stage computational procedure is presented for the accurate determination of transverse normal

This paper is a logical continuation of the 22 parameter, localized orbital correction (LOC) methodology that we developed in previous papers [R. A. Friesner et al., J. Chem. Phys. 125, 124107 (2006); E. H. Knoll and R. A. Friesner, J. Phys. Chem. B 110, 18787 (2006).] This methodology allows one to redress systematic density functional theory (DFT) errors, rooted in DFT�s inherent inability to ...

This paper reports an experimental and computational thermochemical study on 1,3-dimethylbarbituric acid. The value of the standard (p� = 0.1 MPa) molar enthalpy of formation in the gas phase at T = 298.15 K has been determined. The energy of combustion was measured by static bomb combustion calorimetry, and from the result obtained, the standard molar ...

A fundamental understanding of the glass transition is essential for enabling future breakthroughs in glass science and technology. In this paper, we review recent advances in the modeling of glass transition range behavior based on the enthalpy landscape approach. We also give an overview of new simulation techniques for implementation of enthalpy ...

A fundamental understanding of the glass transition is essential for enabling future breakthroughs in glass science and technology. In this paper, we review recent advances in the modeling of glass transition range behavior based on the enthalpy landscape approach. We also give an overview of new simulation techniques for implementation of enthalpy ...

This work reports the enthalpies of formation in the condensed and gas phases of 2-acetyl-1-methylpyrrole and 3-acetyl-1-methylpyrrole, derived from the standard (p(o) = 0.1 MPa) molar enthalpies of combustion, in oxygen, Delta(c)H(m)(o), measured by static bomb combustion calorimetry and the standard molar enthalpies of vaporization, ...

The temperature-dependent mass diffusion coefficient is computed using transition state theory. Ab initio supercell phonon calculations of the entire system provide the attempt frequency, the activation enthalpy, and the activation entropy as a function o...

This paper proposes to show a method of computation of the exergy, B, of any pure substance, using standard data from the literature; it would not be necessary to experimentally determine the enthalpy and entropy of the substance. 3 refs.

Computer programming using NIPROP to calculate the thermal and physical properties of nitrogen is outlined. Pressure, enthalpy, entropy, saturation, and density properties can be calculated. The Joule-Thomson coefficient, surface tension, viscosity, thermal conductivity, refractive index and dielectric constant can be derived.

Computer programming using NIPROP to calculate the thermal and physical properties of nitrogen is outlined. Pressure, enthalpy, entropy, saturation, and density properties can be calculated. The Joule-Thomson coefficient, surface tension, viscosity, therm...

A symbolic mathematics document to provide hands on practice for computing heats of reaction and heat of reaction as a function of temperature given a constant value for Cp.The thermodynamic data required for a large variety of reactions is provided in the file ThDATA.xls.

The thermodynamic and transport properties of para and equilibrium hydrogen have been programmed into a series of computer routines. Input variables are the pair's pressure-temperature and pressure-enthalpy. The programs cover the range from 1 to 5000 psi...

The thermodynamic and transport properties of para and equilibrium hydrogen have been programmed into a series of computer routines. Input variables are the pair's pressure-temperature and pressure-enthalpy. The programs cover the range from 1 to 5000psia...

Thermodynamic data on silicon compounds from numerous sources were stored, sorted and processed by computer. Enthalpies of reactions and formations were determined from the available data by a least squares procedure. (Modified author abstract)

Computational aerothermodynamic simulations of Orbiter windside tile damage in flight were performed in support of the Space Shuttle Return-to-Flight effort. The simulations were performed for both hypervelocity flight and low-enthalpy wind tunnel conditi...

A procedure is described for the generation of chemically accurate computer-simulation models to study chemical reactions in the condensed phase. The process involves (1) the use of a coupled semiempirical quantum and classical molecular mechanics method to represent solutes and solvent, respectively; (2) the optimization of semiempirical quantum mechanics ...

An accurate full-dimensional global potential energy surface (PES) for the F+CH(4)-->HF+CH(3) reaction has been developed based on 19 384 UCCSD(T)/aug-cc-pVTZ quality ab initio energy points obtained by an efficient composite method employing explicit UCCSD(T)/aug-cc-pVDZ and UMP2/aug-cc-pVXZ [X=D,T] computations. The PES contains a first-order saddle ...

... Title : Time-Accurate Computations of Free-Flight Aerodynamics of a Spinning Projectile With and Without Flow Control. ...

Jul 25, 2006 ... PROPOSAL TITLE: Efficient and Accurate Computational Framework for ... to real fluid thermodynamics, as well as turbulent mixing effects. ...

... Accurate Computation of Non-Negative Anisotropic Group Scattering Cross Sections for Discrete Ordinates and Monte Carlo Radiation Transport. ...

... Accession Number : ADD419324. Title : An Accurate, Economical, Solar Insolation Computer Model for the United States,. Corporate Author : ...

A rotating-bomb calorimetric technique was developed to solve the problem of determining accurate values of the enthalpies of combustion of boron and boron compounds. The enthalpies of combustion of crystalline boron, trimethylamineborane ((CH/sub 3/)/sub 3/NBH/sub 3/), and diammoniumdecaborane (B/sub 10/H/sub 18/N/sub 2/) were ...

We present the full enthalpic phase transition cycle for ionic liquids (ILs) as examples of non-classical salts. The cycle was closed for the lattice, solvation, dissociation, and vaporization enthalpies of 30 different ILs, relying on as much experimental data as was available. High-quality dissociation enthalpies were calculated at the G3 MP2 level. From ...

The response of fuel in a boiling water reactor to the rod drop accident (RDA) was studied using the RAMONA-4B computer code. Calculations of this design-basis event has been done conservatively because there was margin to the fuel failure criterion of 170 cal/g. Because high burnup fuel may fail at much lower fuel enthalpies, the best-estimate of the ...

The applicability of the particle image velocimetry (PIV) and the background-oriented schlieren (BOS) techniques in the high-enthalpy shock tunnel G�ttingen of the German Aerospace Center, DLR is demonstrated. As a part of this feasibility study two different experiments are performed. The velocity field past a wedge in a Mach 6 flow at a total specific ...

Objective was to develop computational methods for equilibrium constants of Diels-Alder reactions in gas and liquid solution phases. Approach was to calculate standard enthalpies of formation at 298 K and standard thermodynamic functions for a range of temperatures for reactants and products, and then to calculate standard enthalpies, ...

Recent correlations of the physical properties of dichlorotetrafluoroethane have been used to compute certain thermodynamic properties of this refrigerant. Specific volume, speciflc heat, enthalpy, and entropy of both the saturated and superheated vapor are tabulated over the range - -40 to 294.26 deg F, saturated pressure (minimum) at --40 deg F, ...

such as large molecular weight polyethylene glycols (PEGs) can increase cooling times required for vitri the large enthalpy that must be removed from water when it is �ash-cooled into amorphous ice (which includes a signi�cant fraction of the latent heat of the water�hexagonal ice transition). The required enthalpy

This report presents a prediction method for high-pressure, high-enthalpy constrictor arc heater performance, the conceptual design of 5 MW and 40 MW arc heaters, and supporting documentation. An existing computer code for arc heater performance was modif...

Lignin is an abundant natural resource that is a potential source of valuable chemicals. Improved understanding of the pyrolysis of lignin occurs through the study of model compounds for which phenethyl phenyl ether (PhCH2CH2OPh, PPE) is the simplest example representing the dominant -O-4 ether linkage. The initial step in the thermal decomposition of PPE is the homolytic cleavage of the ...

The enthalpies of combustion, heat capacities, enthalpies of sublimation and enthalpies of formation of 2-methylbenzimidazole (2MeBIM) and 2-ethylbenzimidazole (2EtBIM) are reported and the results compared with those of benzimidazole itself (BIM). Theoretical estimates of the enthalpies of formation were obtained ...

Condensed phase standard (p degrees = 0.1 MPa) molar enthalpies of formation for coumarin and chromone were derived from the standard molar enthalpies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpies of sublimation, at T = 298.15 K, were measured by Calvet ...

The computation of the multinomial distribution function is of interest to many researchers and practicers who are working in the areas of engineering and in the related disciplines of computing sciences. The accurate computation of probabilities is very ...

We have calculated the melting temperature of tungsten by two ab initio approaches. The first approach can be divided into two steps. In the first step, we simulate a large coexisting solid and liquid system by the classical embedded-atom method potential and obtain an approximate melting temperature. In the second step, we compute the accurate melting ...

The enthalpy or calorimetric probe is a water-cooled stagnation/sampling probe for studying the temperature, velocity, and composition of hot-gas flow fields. In order to derive the thermodynamic properties of complex flow fields such as plasma arc jets or high-velocity oxygen fuel jets, the specie concentration must be known accurately. To this end a ...

The inherent difficulty in modeling the energetic character of the B-N dative bond has been investigated utilizing density functional theory and ab initio methods. The underlying influence of basis set size and functions, thermal corrections, and basis set superposition error (BSSE) on the predicted binding enthalpy of ammonia borane (H3B-NH3) and four methyl-substituted ...

Experimental determination of thermodynamic properties (e.g. enthalpy of formation, heat capacity, Gibbs free energy, etc.) is still the recourse for accurate thermodynamic data for the condensed phases. Calorimetry is probably the best experimental method for their determination. Drop calorimetry in its various modifications is still the method of choice ...

Relations were developed that allow easy and accurate calculation of enthalpy changes during the heating, retorting, or cooling of raw, spent, or burned Eastern oil shales. The heat capacities of the mineral matter, bound water, kerogen, and char, and the heat of mineral dehydration are given by linear or quadratic functions of temperature. Values are ...

Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3(-), N5(+), and N5(-) from total atomization energies. Born-Haber cycle calculations, using...

It is found that the Los Alamos (LANL) effective core potential scheme outperforms the Stevens effective core potentials (CEP-31G) for the calculation of gas-phase enthalpies of formation. Inspection of the results indicates that a major source of error is due to the use of effective core potentials for light main group elements (i.e., Z < 10) in the standard CEP-31G ...

Enthalpies of formation were determined by solution calorimetry for UO sub 2 Br sub 2 .H sub 2 O, UO sub 2 Br sub 2 .3H sub 2 O and UO sub 2 (OH)Br.2H sub 2 O. Enthalpy increments, Hdeg(T) - Hdeg(298.15K), were determined for UO sub 2 F sub 2 , UO sub 2 C...

Phase change materials (PCMs) are substances exhibiting phase transitions with large latent heats that can be used as thermal storage materials with a large energy storage capacity in a relatively narrow temperature range. In many practical applications the solid-liquid phase change is used. For applications accurate knowledge of different thermal parameters has to be ...

The excess enthalpy of solutions of light and heavy water was measured in a tilting calorimeter using a plati-num resistance thermometer. Results were represented as a function of the atomic fraction of deuterium n/sub D/ and of the molar fraction of HDO in the solution. At 25 deg C and n/sub D/ = 0.50, DELTA H was 7.65 plus or minus 0.25 cal/mole. It was shown ...

Magnesium phosphates are important constituents of slags encountered in pyrometallurgy and fossil fuel combustion. To compute activities in complex slags, it is important to have accurate data for the pure compounds in the solid and liquid states. The thermodynamic data on magnesium phosphate (Mg[sub 3]P[sub 2]O[sub 8]) given in the recent versions of the ...

EQ3/6 is a software package for geochemical modeling of aqueous systems, such as water/rock or waste/water rock. It is being developed for a variety of applications in geochemical studies for the Yucca Mountain Site Characterization Project. The present focus is on development of capabilities to be used in studies of geochemical processes which will take place in the near-field environment and the ...

... in terms of robustness, accuracy and computational efficiency. ... is fast, computationally efficient, accurate and ... using the tensors toolbox of Matlab. ...

Harding and Goddardl (HGI) computed accurate ab initio potential ... In order to resolve this uncertainty Harding and Goddard ...

There have been a number of attempts to use asteroid populations to simultaneously compute cratering

A formulation is proposed for hybrid LES-RANS computations that permits accurate computations during