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Show 4500,-----------------------------~ ~ I Q) f..4 .3 4000 ro f..4 Q) ~ S Q) +oJ +oJ 3500 C) ~ "'0 o f..4 0... 3000~------._------~------~----~ o 500 1000 1500 2000 Air temperature degrees F F i gu re 7 Adiabatic flame temperature as a function of air preheat temperature for stoichiometric methane-air mixtures at atmospheric pressure, with the fuel initially at room temperature. ..o~.... +oJ C) ro 0.20 -,------------------------------..... 0.15 t: 0.10 Q) .-. o ::s .................................. ..... . ......... . 0.05 ------ --__ ------ CO 0.00 -+-------~------~-------r--------I o 500 1000 1500 2000 Air temperature degrees F Figure 8 Selected species concentrations at equilibrium, plotted as functions of air preheat temperature in stoichiometric methane-air mixtures. 149 ~ .-0 +oJ C) ro f..4 c...... Q) .-. 0 ::;E 0.020 -,------------------------------, 0.015 0.010 0.005 ·····H·· NO ~ ............ ................. ........................ 0.000 -+-------~------,.....---------r-------I o 500 1000 1500 2000 Air temperature degrees F Fi gu re 9 Selected species concentrations at equilibrium, plotted as functions of air preheat temperature in stoichiometric methane-air mixtures. SUMMARY These examples of adiabatic flame temperature and chemical equilibrium composition calculations serve to illustrate several major points. First, the results of such parameter studies provide a significant amount of useful information concerning combustion properties of practical systems. In industries where the accurate prediction of product species concentrations, pollutant emission levels, and operating temperatures is important, there is a continuing need for computational capabilities of this type. The specific examples used here are not revolutionary; in fact, those industries which need such information already use data of this type every day in normal operation. However, the present paper points out the need for continual updating of the thermochemical data base upon which these computations depend. Another point made was that the equilibrium data alone are insufficient to predict some combustor properties such as NOx emission, since the rate of attaining equilibrium is another variable that may not be related to the equilibrium properties themselves. Finally, the current state-of-the-art computer programs for calculating adiabatic flame temperatures, equilibrium compositions, and many other useful thermochemical quantities that this paper has not had the time or space to discuss, are easily obtained, are generally quite simple and convenient to use, and can even be run on personal computers and other |