Effects of pressure on laminar flame characteristics of C1-C3 alkanes: A review

Many natural gas combustion devices work under non-atmospheric pressure, and the pressure has a significant impact on the combustion process. In order to promote the practical application and theoretical research of combustion under different pressures, after summarizing the experimental devices and challenges they faced to achieve elevated pressure and low-pressure combustion, this paper focuses on the influence of pressure on the laminar flame velocity, flame stability and soot formation of C1-C3 alkanes. The results of experiments and kinetic models show that the laminar flame velocity decreases with the increase of pressure, and the prediction accuracy of the kinetic model also decreases at elevated pressure. In the functional relationship of laminar flame velocity and pressure, the law of exponential change with equivalence ratio is different in reports. Elevated pressure accelerates the flickering intensity of diffusion flame and the thermal-diffusion instability as well as hydrodynamic instability of premixed flame. Elevated pressure promotes the soot formation in the diffusion flame, but the maximum yield of soot does not increase after exceeding the critical pressure. The pressure exponent of soot is related to the type of alkane and the pressure range. Finally, based on the summary of existing research, future research needs are presented • Application of natural gas at actual pressure is a way to reduce carbon. • Elevated pressure reduces the laminar flame velocity of C1-C3 alkanes. • Elevated pressure exacerbates instability of diffusion and premixed flames. • Increased pressure before critical pressure promotes soot formation. • Pressure exponent laws of flame velocity and soot are non-linear and non-uniform.