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

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.