Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Thermodynamic Modeling of the Autoignition Temperature
Submission Author:
Bruno Hannud , SP
Co-Authors:
Bruno Hannud, Marcos Pimenta
Presenter: Bruno Hannud
doi://10.26678/ABCM.COBEM2017.COB17-2518
Abstract
The autoignition temperature of 6 fuels was modeled employing lost work analysis. The analysis was performed by dividing an adiabatic premixed flame into two slices, a hot and a cold temperature slice, with an intermediate ignition surface, adopted as reference, and where a single step and complete irreversible chemical reaction occurred. The model employed, an adaptation of the“hot brick problem”, assumed that the chemical work and the heat transferred, available at the ignition surface, were fed back to the two slices, initially in thermal equilibrium at the ignition temperature, so that their temperatures departed from the ignition temperature. The lost work obtained was extremized by forming a Lagrangean with an equality constraint due to the adiabatic condition imposed. The stationary lost work was found to be a maximum. The reference surface’s temperature (where the chemical reaction occurred) was thus found. The results simulate well the autoignition temperatures of methane, ethanol, ethane and propane, but do not seem to validate the autoignition temperatures of hydrogen and carbon monoxide, which seem to require further model refinement.
Keywords
modeling, autoignition temperature, lost work, Optimization
