Introduction to Combustion and Fire

E.g. Internal combustion engines.The stoichiometric unit of measurement is 14.7 (gasoline) but this could fluctuate depending on the compounds that combine and alter the ratio. E.g. for a fuel that is MTBE (methyl tert – butyl ether) laden, the stoichiometric ratio could go down as much as 14:1:1.The higher the temperature, the faster a chemical reaction will occur. The Arrhenius Equation determines the temperature. Molecules collide at higher temperatures. The greater the collision the greater the kinetic energy produced, thereby increasing the activation energy which in turn determines when a reaction takes place.In adiabatic conditions, the temperature increases very rapidly at first but then moves gradually and slowly for a period of time before finally creating a rapid acceleration leading to ignition. The induction period is the duration of a pre-burn lag during which the formation of an initial flare and combustion of fuel vapors takes place.During the process of ignition on a hot plate, the solid combustible material gets ignited if there is a sufficiently high temperature and during the process, there is considerable shrinkage because the material gets consumed gradually because of the heat. During the process of pyrolysis, the temperature field becomes more and more heated due to combustion of the solid material on the hot plate and when it reaches a certain point which is enough or ignition, it gets ignited.Propagation of flames through any combustible material depends on the energy release rate which in turn is determined by the composition of the mixture, the environment and the source of ignition. Therefore the homogenous system is considered flammable when the flammability of the substance reaches a specific temperature and pressure which is then transmitted throughout the mixture.