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Show PREDICTION OF THE FLAMMABILITY LIMITS OF FUEL MIXTURES I. Wierzba and G. A. Karim Department of Mechanical Engineering The University of Calgary Calgary, Alberta, Canada T 2 N 1N4 Abstract Review is made of some relatively simple procedures that may be used to estimate the flammability limits in air of a range of c o m m o n gaseous fuels including accounting for the presence of diluents and different initial temperatures while employing only the known limit values of the individual fuels in air under atmospheric temperature and pressure conditions. Guidelines are also provided for estimating the limits of fuel mixtures containing diluents having a wide range of concentrations on the basis of commonly available data of the individual fuels. Introduction The lean and rich flammability limits are important characteristic properties of any fuel, in the context of safety and utilization. These limits are encountered when a flame initiated from an adequate ignition source just fails to propagate throughout the fuel/oxidant mixture. This failure comes about mainly when the rate of energy release due to chemical reactions within the flame front cannot keep pace with the demands for transporting adequate energy to the adjoining layers of the fresh mixtures, and for overcoming external thermal losses to the surrounding medium. Accordingly, all factors that influence the reaction and transfer processes of the flame and its interaction with the surroundings can influence the value of these limits. Because of the complexity and associated uncertainty of these processes at the limits, the analytical prediction for any set of conditions remains unrealisable at present. The limits are established experimentally at a specified set of operating conditions and apparatus configurations, usually for quiescent homogeneous mixtures [1, 2, 3 ]. In practice, however, virtually unlimited variety of conditions may be associated with the utilization of a certain fuel, yet the corresponding flammability limit data for these conditions often may not be available. The present contribution aims to present a review of some relatively simple procedures that may be used to establish on the basis of the available knowledge of the flammability limits of some common individual gaseous fuels in air usually under atmospheric temperature and pressure, the corresponding values of the limits whether under other conditions or of their mixtures including accounting for the presence of diluents. |