The phenomenon of explosion (or self-ignition, not to be confused with detonation) of fuel mixtures is well known, both as a desired phenomenon, such as the ignition of the fuel in Diesel engines, and as a phenomenon to be avoided, like knocking in SI engines or the risk of fires on oil and gas platforms. The explosion limits are defined as the curve on a pressure-temperature diagram which describes the threshold between the explosive and non-explosive regions of a fuel mixture. These limits are uniquely defined for a specific fuel-oxidizer pair, under a specific ratio and are also partially dependent on the vessel wall surface. For hydrogen and many hydrocarbon fuels distinctive 3-branched limits exist. Although the explosion limits have been studied extensively (experimentally and theoretically) for many years, there exists no model to date which can accurately predict the explosion limits over the complete range, capturing this unique branching behavior.
This research is composed of theoretical investigation of the explosion limits of an H2-O2 mixture, with the objective of understanding fundamental governing physics of the explosion limits, especially in regards to the uniqueness of the branching limits. We also aim to develop a universal explosion criterion for H2-O2 mixtures, and gain insights into the explosion process for other fuel types. By using a novel approach, combining elements of chain ignition theory and linking between the explosion limits and the ignition delay, we present a unified model capable of accurately predicting the explosion limits of H2-O2 mixture. We also investigate the effects of fluctuations at the molecular level, to evaluate the effect of different impurities in the mixture on the explosion initiation. Our results from the different models developed and the conclusions and insights gained about the explosion phenomenon will be presented in the talk.