Reaction kinetics for high pressure hydrogen oxy-combustion in the presence of high levels of H2O and CO2

Novel shock tube experimental ignition delay time (IDT) data are provided to delineate the impact of high concentrations (45% by mole) of H2O and CO2 on IDTs of stoichiometric 4% H2. Ignition delay experiments were conducted using a high- and a low-pressure shock tube facility. High-pressure experiments were performed at pressures of 37-43.8 bar and temperatures of 1084-1242 K in four different bath gases, namely: Ar, 45%H2O/Ar, 30%H2O/15%CO2/Ar, and 45%CO2/Ar. Low-pressure experiments were conducted at 2.1-2.7 bar and 926-1198 K in Ar and 45%CO2/Ar bath gases. Impacts of non-ideal ignition phenomena that may occur in the presence of large amounts of H2O and CO2 were also analyzed. A minimally-tuned H2/CO reaction mechanism, CanMECH 1.0, targeting high-pressure combustion in the presence of large concentrations of H2O and CO2 is presented. The mechanism is constructed from unadjusted kinetic rate parameters from theoretical / experimental elementary reaction rate determinations. The only adjusted rate in CanMECH 1.0 is the much disputed Ar-specific low-pressure-limit pre-exponential factor of H + O2 (+Ar) = HO2 (+Ar) within the uncertainty bounds of the source rate. Validity of CanMECH 1.0 is confirmed against shock tube IDT data of this work, as well as selected H2 and H2/CO shock tube IDT datasets from literature. The performance of the model is compared to Keromnes et al. model (Combust. Flame 160 (2013) 995-1011). CanMECH 1.0 outperformed Keromnes et al. for 16 datasets out of 26 and exhibited a similar performance for another two. In particular, CanMECH 1.0 outperformed Keromnes et al. in predicting shock tube IDTs for H2O- and CO2-laden reactive mixtures, as well as all IDT data at pressures of 17-43.8 bar, which are of distinct value to pressurized oxy-fuel combustion applications relevant to this work.