Effect of diluent gas on propagation and explosion characteristics of hydrogen-rich syngas laminar premixed flame

Abstract

Syngas, a promising renewable alternative fuel, shows different combustion characteristics depending on its exact composition. In this study, the effect of different diluents on the laminar premixed flame of hydrogen-rich syngas was experimentally investigated using a 90% H2/10% CO/air mixture in a constant-volume combustion bomb. In particular, this investigation revealed the effects of varying the equivalence ratio (0.6, 0.8, and 1.0) and dilution content (10%, 20%, and 30%) on the flame propagation and explosion characteristics of syngas/air mixture. The results showed that for a given dilution gas content, the flame propagation speed under CO2 dilution is less than that under N2 dilution; however, the flame acceleration effect of CO2 dilution is significantly higher than that of N2. As the dilution increases, the rate of pressure rise and the maximum combustion explosion pressure gradually decrease. For a given equivalence ratio, the maximum rate of pressure rise and the deflagration index of the flame mixed with N2 were higher than those for CO2.