A review on mixing laws of laminar flame speed and their applications on H2/CH4/CO/air mixtures

As one of the most promising environmentally-friendly and renewable energies, biomass derived gas (BDG) has a great application prospect in the future energy system. Due to complex diversity of BDG components, the prediction of the important parameters, such as laminar flame speed, from the individual component will be realistic and reasonable than those from the direct measurement or calculation in some circumstances. In this study, existing mixing models are evaluated to predict the laminar flame speed of BDG. In addition, one-dimensional laminar premixed flame propagations are simulated to analyze flame temperatures and sensitivity coefficients of the laminar flame speed. For BDG with main components of CH4, H-2 and CO, we employ the strategy that CH4 and H-2 are mixed first and then wet CO is added into CH4/H-2 mixture. For CH4/H-2 blended fuels, flametemperature-based and Le Chaterlier's models have the best fits for the laminar flame speed estimations of CH4/H-2/air mixtures with lower and higher Z(H2), respectively. Sensitivity analysis shows there are large discrepancy in chemical pathways for BDG with higher or lower Z(CO) and the laminar flame speed prediction of BDG will be conducted in two different circumstances. When CO ratio is lower than 0.85, Spalding rule and energy fraction method could predict the laminar flame speed best. For BDG with CO ratio larger than 0.85, Spalding rule and Chen's model are the best choices to predict the laminar flame speed of BDG. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.