Review of the Studies on Chemical Kinetics of C1–C4 Alkanes Combustion in O2/CO2 Environment Based on Laminar Burning Velocity, Ignition Delay Times and Species Concentration Measurements

Direct-fired supercritical CO2 cycles are considered a promising way to reduce CO2 emissions in the energy sector. One of the key elements of such cycles is a combustor, in which natural gas is burned at supercritical pressures up to 300 atm in an O2/CO2 environment. Understanding the chemical combustion kinetics of C1–C4 alkanes, the main components of natural gas, in a supercritical CO2-diluted medium is important for designing such combustors. This article provides an overview of studies on the chemical kinetics of C1–C4 alkanes combustion in CO2 at ultra-high pressures. It has been established that with increasing pressure, regardless of the diluent, CH3O2 and HO2 chemistries start to significantly influence the combustion of alkanes, but at the moment this influence is not sufficiently understood. Influence of CO2 dilution on kinetics is mainly thermal, but the chemical effect is also significant. At the same time, the direct chemical effect of CO2 is more important for the laminar burning velocity, while the indirect third-body effect is more important for the ignition delay time. However, the available literature lacks experimental measurements of the laminar burning velocity in a CO2 environment at pressures above 70 atm, which limits the current understanding of chemical kinetics at supercritical pressures.