The influence of porous wall on flame length and pollutant emissions in a premixed burner: an experimental study

In this experimental research, a porous wall is used to stabilize a premixed flame. The effect of the porous wall on the flame length, CO, and NOx emissions for natural gas and air combustion is studied at a fixed power burner. A cylindrical flame holder with 154 mm length, 90 mm inner diameter, and 160 mm outer diameter is used as a combustion chamber. The SiC porous walls have outer diameter of 90 mm, inner diameter of 40, 50, and 60 mm, pore density of 10, and 30 PPI, and length of 22, 44, and 66 mm. A Testo 350 XL gas analyzer is used to measure emission pollutants. It is observed that the flame length increases with an increase in the pore density and the length of porous wall and a decrease in the inner diameter of porous wall. An appropriate correlation is proposed to estimate the flame length at constant pore density and power burner. Also, the results revealed that NOx concentration increases with increasing inner diameter and length of porous wall and decreases with increasing pore density of porous wall. CO results show that CO concentration only depends on the equivalence ratio and the physical characteristics of the porous wall does not affect it.