In combustion, heat release parameter (or gas expansion parameter) is a dimensionless parameter which measures the amount of heat released by an adibatic combustion process.[1][2] It is defined as
![{\displaystyle q={\frac {T_{ad}-T_{u}}{T_{u}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/eb64791b74d718f4588fbe98fde2cb6c6aa71bab)
where
In typical combustion process,
. For isobaric combustion, using ideal gas law, the parameter can be expressed in terms of density,[3] i.e.,
![{\displaystyle q={\frac {T_{ad}-T_{u}}{T_{u}}}={\frac {\rho _{u}-\rho _{ad}}{\rho _{u}}}.}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5af0f8e60ebf90cd7c4d8a8588ecb29cb72ed39d)
The ratio of burnt gas to unburnt gas temperature is
![{\displaystyle {\frac {T_{ad}}{T_{u}}}=1+q.}](https://wikimedia.org/api/rest_v1/media/math/render/svg/af21f8595c91ec6158577726262b8d398dc457fe)
- ^ Williams, Forman A. "Combustion theory." (1985).
- ^ Linan, Amable, and Forman Arthur Williams. "Fundamental aspects of combustion." (1993).
- ^ Clavin, P. (1985). Dynamic behavior of premixed flame fronts in laminar and turbulent flows. Progress in energy and combustion science, 11(1), 1-59.