Pressure and temperature influence on propagation indices of n-butane-air gaseous mixtures

The combustion of n-butane-air in a closed spherical vessel with central ignition was studied at various initial pressures within 0.3-1.3 bar and initial temperatures within 298-430 K, by means of transient pressure-time records. The propagation indices of confined deflagrations in the quiescent stoichiometric mixture are reported: the peak explosion pressure, the explosion time, the maximum rate of pressure rise and the related severity factor. The measured propagation indices are compared with the propagation indices computed under the assumption of an adiabatic propagation. Based on explosion pressure variation with the initial temperature, the heat of combustion of n-butane with air, corrected for the endothermic processes in the burned gas, was determined.