Libraries of thermodynamic data and transport properties are given for individual species in the form of least-squares coefficients. Values of C(sup 0)(sub p)(T), H(sup 0)(T), and S(sup 0)(T) are available for 1130 solid, liquid, and gaseous species. Viscosity and thermal conductivity data are given for 155 gases. The original C(sup 0)(sub p)(T) values were fit to a fourth-order polynomial with integration constants for H(sup 0)(T) and S(sup 0)(T). For each species the integration constant for H(sup 0)(T) includes the heat of formation. Transport properties have a different functional form. The temperature range for most of the data is 300 to 5000 K, although some of the newer thermodynamic data have a range of 200 to 6000 K. Because the species are mainly possible products of reaction, the data are useful for chemical equilibrium and kinetics computer codes. Much of the data has been distributed for several years with the NASA Lewis equilibrium program CET89. The thermodynamic properties of the reference elements were updated along with about 175 species that involve the elements carbon, hydrogen, oxygen, and nitrogen. These sets of data will be distributed with the NASA Lewis personal computer program for calculating chemical equilibria, CETPC.

Coefficients for calculating thermodynamic and transport properties of individual species

This report documents the library of thermodynamic data used with the NASA Glenn computer program CEA (Chemical Equilibrium with Applications). This library, containing data for over 2000 solid, liquid, and gaseous chemical species for temperatures ranging from 200 to 20,000 K, is available for use with other computer codes as well. The data are expressed as least-squares coefficients to a seven-term functional form for C((sup o)(sub p)) (T) / R with integration constants for H (sup o) (T) / RT and S(sup o) (T) / R. The NASA Glenn computer program PAC (Properties and Coefficients) was used to calculate thermodynamic functions and to generate the least-squares coefficients. PAC input was taken from a variety of sources. A complete listing of the database is given along with a summary of thermodynamic properties at 0 and 298.15 K.

NASA Glenn Coefficients for Calculating Thermodynamic Properties of Individual Species

Detailed chemical kinetic modeling has been performed to investigate aromatic and polyaromatic hydrocarbon formation pathways in rich, sooting, methane and ethane premixed flames. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.5 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph / mass spectrometer technique. Measurements were made in the flame and post-flame zone for a number of low molecular weight species, aliphatics, aromatics, and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-aromatic fused rings. The modeling results show the key reaction sequences leading to aromatic and polycyclic aromatic hydrocarbon formation primarily involve the combination of resonantly stabilized radicals. In particular, propargyl and I-methylallenyl combination reactions lead to benzene and methyl substituted benzene formation, while polycyclic aromatics are formed from cyclopentadienyl and f...

Modeling of Aromatic and Polycyclic Aromatic Hydrocarbon Formation in Premixed Methane and Ethane Flames

It has long been recognized that the key intermediates for the majority of the reactions of organic molecules in the gas phase, and frequently in the liquid phase as well, are free radicals. An important prerequisite for the description of the behavior of such systems is their thermodynamic properties. At first glance it may be surprising that thermodynamic properties should have any applicability to transient species that are present in trace quantities and disappear in short times. Indeed, if the kinetic properties of such systems are known, then thermodynamic properties are not really necessary and can in fact be derived from the kinetics. In reality, however, kinetic properties may be unavailable or difficult to measure. Thermodynamic properties serve as limits for kinetics and more generally as a basis for the estimation and evaluation of kinetic information [1]. More directly, through the equilibrium constant, rate constants for the reverse direction can be directly calculated from that in the forward direction. There are other physical situations where local thermodynamic equilibrium turns out to be a satisfactory approximation and kinetic information is not important.

Heats of Formation of Organic Free Radicals by Kinetic Methods

Resonance Energy Calculation; the MM2ERW Force Field*



The additivity of the thermochemical conjugation energy in acyclic systems allows one to extend force-field calculations to conjugated π systems without embarking on quantum-mechanical methods. The approach fails with cyclic delocalized systems, where resonance effects become important. Here the method provides the reference value needed to calculate resonance energies.

Die Berechnung von Resonanzenergien; das MM2ERW‐Kraftfeld

Measurements of the dissociation and reverse recombination rates of toluene, benzyl iodide, and dibenzyl in shock waves have provided a direct access to the dissociation equilibria. A third-law analysis of these data is made, providing a new value of the enthalpy of formation of benzyl of ΔH f o 298 =210.5± 4 kJ mol −1 which is higher than that given by earlier evaluations

J. Troe

Papers

Thermodynamic properties of benzyl radicals: enthalpy of formation from toluene, benzyl iodide, and dibenzyl dissociation equilibria

Thermodynamic Properties of Benzyl Radicals: Enthalpy of Formation from Toluene, Benzyl Iodide, and Dibenzyl Dissociation Equilibria.