Effect of swirl on performance of foam porous medium burners

The effect of swirl on combustion inside a foam porous medium burner was investigated in terms of stability, radiation intensity, gaseous emissions, gas and solid temperatures. The swirl was imparted by motorizing the burner tube with a variable speed motor in order to increase the convective heat transfer coupling between the two media, as well as turbulence. Modifications to the radial flow burner that has been recently investigated for rotation were employed by switching to an axial flow rotary-vane foam burner. The no-swirl and swirl firing conditions for a methane/air mixture revealed a lean operation as low as 0.507 in terms of equivalence ratio associated with NOx concentrations of 0-1 ppm, and 50 ppm for CO. Results of swirl effect revealed a relative increase in radiation intensity up to 50%, a some gain in exhaust gas temperatures, and a one digit NOx concentration ( less than 10 ppm) over the entire operating range of equivalence ratios. A numerical model based on single-step kinetics and diffusion-radiation approximation depicted the stability performance of the burner and the increase in solid temperature with the volumetric heat transfer coefficient.