Combustion thermodynamic properties

Adiabatic flame temperatures agree with values measured by optical techniques, when the combustion is essentially complete and when losses are known to be relatively small. Calculated temperatures and gas compositions are thus extremely useful and essential for assessing the combustion process and predicting the effects of variations in process parameters (4). Advances in computational techniques have made flame temperature and equifibrium gas composition calculations, and the prediction of thermodynamic properties, routine for any fuel-oxidizer system for which the enthalpies and heats of formation are available or can be estimated. 

Computes thermodynamic properties of air, argon, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, water vapor, and products of combustion for hydrocarbons. Computes all properties from any two independent properties. 

The thermodynamic properties of thiophene,2-methylthiophene, ° and 3-methylthiophene have been computed from careful measurements of the heat capacity of the solid, liquid, and vapor states, the heat of fusion, the heat of vaporization, and the heat of combustion. From the heat of combustion of thiophene and from thermochemical bond energies, the resonance energy of thiophene has been re-estimated to be only 20 kcal/mole. 

Based on thermodynamic property of each element, the behavior of trace metals in the coal combustion process was generally classified into 3 groups as follows ... 

Smith, N.K., Stewart, Jr., R.C., Osbom, A.G. (1980) Pyrene vapor pressures, enthalpy of combustion, and chemical thermodynamic properties. J. Chem. Thermodyn. 21, 919-926. 

In marked contrast to the n-alkanes, the cycloalkanes exhibit thermodynamic properties where such regularities are no longer present. Heats of formation (AH ) for a substantial number of cycloalkanes are available from heats of combustion. With the exception of cyclohexane, AH°f is always more positive than the quantity — 4.926n. The difference between the two quantities leads to a quantitative assessment of the important notion of ring strain. The AH -values and strain energy data listed in Table 1 were taken from Skinner and Pilcher (1963). Other references give different but usually comparable... 

J. D. Cox, H. A. Gundry, A. J. Head. Thermodynamic Properties of Fluorine Compounds. Part 1. Heats of Combustion ofp-Fluorobenzoic Acid, Pentafluorobenzoic Acid, Hexafluorobenzene, and Decafluorocyclohexene. Trans. Faraday Soc. 1964, 60, 653-665. 

I. Tomaszkiewicz, G. A. Hope, C. M. Beck II, P. A. G. O Hare. Thermodynamic Properties of Silicides. VI. Pentamolybdenum Trisilicide (Mo Sf). Fluorine Combustion Calorimetric Determination of the Standard Molar Enthalpy of Formation at the Temperature of 298.15 K. J. Chem. Thermodynamics 1997, 29, 87-98. 

Recent experimental results on thermodynamic properties of high pressure supercritical fluids have opened up the possibility to study combustion and flames at very high pressures and in unusual environments. Stationary diffusion flames have been produced up to 2000 bar in dense aqueous mixed fluid phases. 

An example in this regard is provided by the titanium-promoted reductive dimerization [3-5] pentacyclic monoketones and their monomethylated analogs, as indicated in Scheme 1. We have successfully prepared these compounds in relatively large quantities (i.e., several hundred grams). Samples have been sent to other laboratories for evaluation of their fuel properties, selected thermodynamic properties, and combustion characteristics. 

Farber, Thermodynamic Properties of Rocket Combustion Products and Nozzle Material , AFOSR, Contract F44620-69-C-0071 (1974) [AD-777180] 15) Merck (1976), 1273 (No... 

Thermodynamic properties of C60H36 (Lebedev et al. 2000) are presented in Table 4.1 as well as the A H°m (C60H36, cr) value determined from the combustion experiments for three samples with different DHA content (0.11-0.33 mas.%). 

The prediction of rocket propellant specific impulse, as well as impulse under other conditions, may be reliably accomplished by calculation using as input the chemical composition, the heat of formation, and the density of the component propellant chemicals. Not only impulse but also the composition of exhaust species (and of species in the combustion chamber and the throat) may be calculated if the thermodynamic properties of the chemical species involved are known or can be estimated. The present standard computer code for such calculations is that described by Gordon and McBride.44 Theoretical performance predictions using such programs are widely used to guide propellant formulation efforts and to predict rocket propellant performance however, verification of actual performance is necessary. 

As broad as the coverage of this symposium appears, there is much propellant chemistry which has not been included. The experimental determination of thermodynamic properties such as heats of formation and equilibrium constants as well as the calculations of theoretical performance have been presented at other symposia. The applied chemistry related to modifying polymers, and hence mechanical and burning properties of solids, have other forums. The actual firing of solid motors and determination of thrust and efficiency have been omitted while the research into combustion instability and the transition from deflagration to detonation are only alluded to. 

---