Experimental study of n-heptane/air combustion in meso-scale burners with porous media

•Quartz microcombustors with and without porous medium were fabricated.•Absence of the porous medium leads to temperature oscillation of droplet combustion.•Heat transfer characteristics of one-layer and two-layer vacuum outer tubes were examined.•Positions of porous medium affect the flame stability.•Reynolds and fuel flow rate affect flame positions and heat loss of the burners.

The liquid fuel combustion in a meso-scale burner with porous media was experimentally investigated for n-heptane/air mixtures of varying equivalence ratios and flow speeds. Infrared thermography and appropriately placed thermocouples were to measure the surface temperature of the burner. A video camera recorded changes in the flame. Liquid heptane combustion in a meso-scale burner was demonstrated to be affected by many factors. First, heptanes droplets were formed at the capillary tip, and oscillating combustion occurred in the absence of a porous medium, resulting in an unstable flame, which could be easily blown out. Second, the addition of a porous medium stabilized the flame, but its position was affected by the airflow velocity and the position of the porous medium. Finally, the outer tube affected the flammable limits of the burner. The flame could easily be blown out in the absence of an outer tube. Furthermore, a double-layer vacuum tube insulated the burner more effectively and significantly reduced its heat loss.