Influence of equivalence ratio on emissions in meso-scale vortex combustor.

Abstract

The miniaturization of small-size power supply systems with high energy density is becoming essential nowadays. The demand for compact, lightweight power has motivated researchers to actively develop the small reacting system. However, reducing size in the combustion system has encountered some technical challenges. This study has also been motivated by the speedy development of mesoscale electrical and mechanical systems. This paper presents biogas' numerical flame characteristics (60% CH4 -40% CO2) in an asymmetric mesoscale vortex combustor. The results indicate that the lean equivalence ratio limit was Ø 0.51 for all Re, the stable range is large at low Re (0.51< Ø <1.86 at Re 2500), decreasing with increasing Re until (0.51< Ø <0.56) at Re 7840. A strong vortex forms a stable zone for the flame and demonstrates the high stability of biogas flame for the mesoscale combustor. Flame stability in mesoscale vortex combustion has been due to two important effects; the strong tangential vortex controls the flame field and vortex influence. The rich equivalence ratio at Ø 1.86 was recorded as the highest peak temperature at 1870 K. It produced the highest value for CO and NOx gases emissions, at 5.65 e-04 ppm and 10.06 ppm, respectively. Meanwhile, the lean equivalence ratio, Ø 0.56, recorded the lowest peak temperature at 1533 K but interestingly managed to produce the lowest CO and NOx gas emissions value, at 1.43 e-07 ppm 1.2132 ppm, respectively. Thus, it concluded that the higher ratio of air in the fuel, the lower the temperature and emissions.