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

The threat of global warming caused by greenhouse gases such as CO to the environment is one of the most intractable challenges. The capture and utilization of CO are essential to reduce its emission and achieve the goal of being carbon neutral, in which CO-diluted combustion is an efficient carbon capture technology. In this research, the effects of CO addition in the fuel side (CO-F), oxidizer side (CO-O) and both sides (CO-F/O) on temperature and soot formation in CH/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 CH/air laminar co-flow diffusion flames were measured employing the inverse Abel transform. The results demonstrated that the effect of amount variation of CO-F on the decrease of flame temperature was enhanced by the CO-O. The reduction in peak flame temperature was 4 K in the CO-F cases, while the reduction in peak flame temperature was 83 K in the CO-F/O cases. The soot formation was suppressed significantly by the effects of CO-F/O. Compared with the CO-F cases, the reductions in peak soot volume fraction were 22.5% and 23.5% in the CO-F/O cases. The suppression effect of amount variation of the CO-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 CO-F cases, and the corresponding reductions were 4.92%, 5.2% and 16% in the CO-F/O cases, respectively.