Experimental study of the effect of CO2 on temperature and soot volume fraction in C2H4/air co-flow laminar diffusion flame

Abstract

The threat of global warming caused by greenhouse gases such as CO2 to the environment is one of the most intractable challenges. The capture and utilization of CO2 are essential to reduce its emission and achieve the goal of being carbon neutral, in which CO2-diluted combustion is an efficient carbon capture technology. In this research, the effects of CO2 addition in the fuel side (CO2-F), oxidizer side (CO2-O) and both sides (CO2-F/O) on temperature and soot formation in C2H4/air laminar co-flow diffusion flames were researched. The flame images were measured by a complementary metal-oxide-semiconductor (CMOS) imaging equipment. The two-dimensional distributions of temperature and soot volume fraction in C2H4/air laminar co-flow diffusion flames were measured employing the inverse Abel transform. The results demonstrated that the effect of amount variation of CO2-F on the decrease of flame temperature was enhanced by the CO2-O. The reduction in peak flame temperature was 4 K in the CO2-F cases, while the reduction in peak flame temperature was 83 K in the CO2-F/O cases. The soot formation was suppressed significantly by the effects of CO2-F/O. Compared with the CO2-F cases, the reductions in peak soot volume fraction were 22.5% and 23.5% in the CO2-F/O cases. The suppression effect of amount variation of the CO2-F on soot formation became more significant with the increase of flame height. The reductions in peak soot volume fractions were 0.3%, 3.07% and 6.38% at the flame heights of 20 mm, 30 mm and 40 mm in the CO2-F cases, and the corresponding reductions were 4.92%, 5.2% and 16% in the CO2-F/O cases, respectively.