Thermodynamic calculations, calculator program

Comparison of Four Thermodynamic Calculation Computer Programs ... 

CHEMKIN REAL-GAS A Fortran Package for Analysis of Thermodynamic Properties and Chemical Kinetics in Nonideal Systems, Schmitt, R. G., Butler, P. B. and French, N. B. The University of Iowa, Iowa City, IA. Report UIME PBB 93-006,1993. A Fortran program (rglib.f and rgin-terp.f) used in connection with CHEMKIN-II that incorporates several real-gas equations of state into kinetic and thermodynamic calculations. The real-gas equations of state provided include the van der Waals, Redlich-Kwong, Soave, Peng-Robinson, Becker-Kistiakowsky-Wilson, and Nobel-Abel. 

A new computer program CSMGem, for hydrate thermodynamic calculations... 

Flame Temperature Measurements. Thermodynamic calculations of the nature of the products of hydrazine perchlorate self-deflagration at a series of processes were performed by an IBM-7090 computer program. The results are shown in Table V. The calculations were made assuming... 

We have seen that calculating species properties from experimental values of K and A // ° is more complicated than calculating K and Ar ° from species values. Thermodynamic calculations can be made by alternate paths, and so there is more than one way to calculate species properties from experimental properties. This chapter emphasizes the concept of the inverse Legendre transform discussed by Callen (8). Biochemical reaction systems are described by transformed thermodynamic properties, and the inverse transform given in equation 6.2-1 provides the transformation from experimental reactant properties to calculated species properties. In this ehapter we first considered calculations of species properties at 298.15 K from measurements of K and Ar ° at 298.15 K. Then we considered the more difficult problem of calculating Af G°(298.15 K) and Af //°(298.15 K) from Ar G "(313.15 K) and Ar H (313.15 K). The programs developed here make it possible to go from Ar G and Ar H (F.pH,/) to Af G (298.15 K,/=0) and Af H (298.15 K,/=0) in one step. 

Equilibrium compositions of systems of chemical reactions or systems of enzyme-catalyzed reactions can only be calculated by iterative methods, like the Newton-Raphson method, and so computer programs are required. These computer programs involve matrix operations for going back and forth between conservation matrices and stoichiometric number matrices. A more global view of biochemical equilibria can be obtained by specifying steady-state concentrations of coenzymes. These are referred to as calculations at the third level to distinguish them from the first level (chemical thermodynamic calculations in terms of species) and the second level (biochemical thermodynamic calculations at specified pH in terms of reactants). 

Samsonov [15] studied the direct sorption of ALA and other dipolar ions by SDV-3 ion exchanger resin at pH = 7. The enthalpy and entropy components of these sorptions were obtained from the isotherm dependence on temperature. It was found that the transformation of the resin from the hydrogen to the amino acid form was accompanied by a rise in the system s entropy. The thermodynamic-based description of the exchange of a-amino acids with hydrogen on three ion-exchange resins at pH < pK .co2 were determined as well. However, precise descriptions of the experimental measurements and the calculations program used were not given. 

Frequently process plants contain recycle streams and control loops, and the solution for the stream properties requires iterative calculations. Thus efficient numerical methods for convergence must be used. In addition, appropriate physical properties and thermodynamic data have to be retrieved fi om a data base. Finally, a master program must exist that links all the building blocks, physical property data, thermodynamic calculations, subroutines, and numerical subroutines, and that also supervises the information flow. You will find that optimization and economic anafy-sis are really the ultimate goal in the use of flowsheet codes. 

Modelling calculations were performed for Crooks Gap and Bonanza to determine how much calcite could dissolve given sufficient time to reach equilibrium between calcite and the added CO2. The purpose of the calculations was to determine how far from equilibrium the natural systems were, and to assess the potential for using a thermodynamic equilibrium modelling program to predict well bore scale (discussed in the next section). 

As process simulation programs become routine tools, many engineers treat their thermodynamic calculations as a black box without giving thought to the underlying data or models. To their credit, developers of process simulators have spent much effort to validate both data and models. However, it is unwise to put blind trust in numbers merely because they are produced by... 

SMCPS (Statistical Mechanics for Heat Capacity and Entropy Cp and S) is a Fortran program written by Sheng [74]. This program is useful for users of computational chemistry, such as Gaussian 98 [64], to calculate thermodynamic properties for molecules with hindered rotations. Required input parameters to SMCPS can be extracted from Gaussian98 calculations to determine the desired thermodynamic properties. The thermodynamic properties can then be directly applied to kinetic models, or other systems requiring thermodynamic properties. The program assumes the system of interest is at one atmospheric pressure, where most of literature thermodynamic data are found. 

Phase-equilibrium calculations were discussed for vapor-liquid equilibria (VLB), liquid-liquid equilibria (LLE), and solid-solid equilibria (SSE). Results from VLE calculations often take the form of K-factors and relative volatilities, especially when thermodynamic calculations serve as intermediate steps in computer-aided process-design programs. In those situations, K-factors are routinely provided to subprograms that size distillation columns and gas-liquid absorbers. Similarly, the distribution coefficients computed for LLE serve as bases for sizing solvent-extraction columns moreover, liquid-liquid distribution coefficients may be helpful in screening candidate solvents for use in an extraction. 

All the thermodynamic calculations performed by CHETAH are for species in the gas phase. Since most chemical processing is carried out in the condensed phase this may seem a weakness. However, in most cases the deviations from the condensed phase values are either too small to affect the result significantly or can be estimated by other means. Also, the correlations used in the hazard evaluation section of the program are based on experimental data for condensed phase species. 

Thermodynamic calculations were performed using THERMO software package to calculate the adiabatic combustion temperatures and product phase distribution. This program is based on optimization of Gibbs free energy of multiphase and multicomponent systems. The gases are assumed to be ideal and condensed phases completely immiscible [19],... 

For the calculation of thermodynamic equilibria the Gibbs energy of the system is minimized at given temperature and pressure as a function of the composition of all the reactants and reaction intermediates. Boundary conditions are the amounts of the reactants that enter the reactor. Also the stoichiometric coefficients of the reactions are constraints in the minimization. Commercial programs for routine thermodynamic calculations are SOLGASMIX, CHEMSAGE, or HSC. 

The ENIVEL Program is a general purpose vapor-llquid-solid aqueous electrolyte simulation program in which the model is specified as a set of chemical equations in standard form. All necessary equations for equilibrium, electroneutrality and material balance are automatically generated and solved. The program can also perform nonaqueous thermodynamic calculations. 

The predictions of CO are based on a thermodynamic equilibrium computer program in which the chemical equilibrium compositions for assigned thermodynamic states are calculated. Most often temperature and pressure, calculated from the main CFD code, are used to specify the thermodynamic state. The method for evaluating the equilibrium compositions is based on the minimization of Gibbs energy as mentioned earlier (Wang et al., 2006). 

As we see, the reaction gases at the loading density of 100 g/1 agree very well with the equilibrium gases, which were thermodynamically calculated [2] using the ICT-computer-program. 

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