Laminar burning velocity of multi-component gaseous mixtures

The laminar burning velocity is the essential parameters for the safe design of equipment and process. Indeed, the knowledge of this parameter allows for the definition of flammability limits, minimum oxygen concentration and the gas deflagration index, Kg. Recently, the interest in the laminar burning velocity has raised because of the increased use of complex gaseous mixtures derived from biological (biogas), or pyrolysis and gasification (syngas) processes. Due to the large number of components of these gases, simplified correlations for the definition of the additivity of the burning velocity are questionable. Furthermore, the presence of carbon monoxide, hydrogen sulphide, ammonia and hydrogen, or other non-hydrocarbon substances, may strongly affect the correlation results. Le Chatelier's formula e.g. may produce an error of over 25% with respect to the experimental data for simple mixtures based on two hydrocarbon fuels. In this work, a review of the main additivity rules for the definition of the laminar burning velocity for multicomponent mixtures (≥ 3 fuels) is given, starting from the pioneering correlations and analysis of Spalding. The equations have been compared and validated with respect to experimental data. A comparison with the results obtained by using more recent advanced kinetic mechanism, which can be adopted for the prediction of mixture reactivity, is also given.