Heat release parameter: Difference between revisions

Revision as of 13:33, 9 July 2024

Revision as of 09:09, 10 July 2024

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In [[combustion]], '''heat release parameter''' (or '''gas expansion parameter''') is a dimensionless parameter which measures the amount of heat released by the combustion process.<ref>Williams, Forman A. "Combustion theory." (1985).</ref><ref>Linan, Amable, and Forman Arthur Williams. "Fundamental aspects of combustion." (1993).</ref> It is defined as

:<math>\alphaq = \frac{T_bT_{ad}-T_u}{T_bT_u}</math>

where

*<math>T_bT_{ad}</math> is the burnt[[adiabatic gasflame temperature]]

*<math>T_u</math> is the unburnt mixture temperature.

In typical combustion process, <math>\alphaq\approx 0.73-0.98</math>. For [[isobaric process|isobaric]] combustion, using [[ideal gas law]], the parameter can be expressed in terms of [[density]],<ref>Clavin, P. (1985). Dynamic behavior of premixed flame fronts in laminar and turbulent flows. Progress in energy and combustion science, 11(1), 1-59.</ref> i.e.,

:<math>\alphaq = \frac{T_bT_{ad}-T_u}{T_bT_u} = \frac{\rho_u-\rho_brho_{ad}}{\rho_u}.</math>

The ratio of burnt gas to unburnt gas temperature is

:<math>\frac{T_bT_{ad}}{T_u} = \frac{\rho_u}{\rho_b}=\frac{1}{1-\alpha}+q.</math>

==Gas expansion ratio==

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:<math>r = \frac{\rho_u}{\rho_b}</math>

which is related to <math>\alpha</math> by <math>r=1/(1-\alpha)+q.</math>

==See also==