Numerical calculation of the laminar flame speed of low calorific gases

Laminar flame speed is an important parameter of the combustion process. It plays a crucial role in issues connected with the flame stability. There are many experimental methods of determination laminar flame speed of gaseous fuels, nevertheless they are very often quite complex. This is an especially big disadvantage when there is a necessity of laminar flame speed determination of not typical gases. Low calorific gases (i.e. from biomass waste gasification process) are an example of such fuel. Such gases may be characterized by high variability in composition depending on the process conditions and fuel composition before process. For this reason it is extremely important to know the basic properties of such gas. Numerical methods of the laminar flame speed calculations are quite good alternative in comparison to experimental methods. They give the opportunity to change many parameters of the process at the same time. It is especially important when general characterization of the new low calorific gaseous fuel is the most important aspect of the research. The aim of the work was numerical analysis of the laminar flame speed of the waste biomass gasification gas. Cosilab 3^© software and following two mechanisms, namely GRI-Mech 3.0 and USC-Mech were used. Results show that the laminar flame speed value increases as the molar fraction of hydrogen in the fuel goes up. Interestingly, the laminar flame speed increases rapidly as the amount of hydrogen increases from 5 to 17%. The laminar flame speed calculated using GRI-Mech 3.0 were slightly larger than the simulation results calculated using USC-Mech II during the entire duration of this study.