Flame stability and combustion characteristics of liquid fuel in a meso-scale burner with porous media

To overcome difficulties of complete evaporation and mixing of liquid fuel in limited resident time and space, a self-evaporation meso-scale burner is proposed. Combustion characteristics at various inlet conditions are experimentally investigated. Results show that liquid n-heptane can be evaporated completely in porous media without external heating. Porous media temperature near fuel outlet is closely related to flame stability and significantly affected by air flow. Generally, using larger fuel flow rate and keep the porous media temperature near fuel outlet below the boiling point can prevent the flame from violent oscillation or extinction. When the porous media temperature near fuel outlet is much lower than boiling point, increase of porous media temperature changes fuel evaporation process and increases fuel velocity, which increases the flame length and soot. However, when porous media temperature is higher than the boiling point, improvement of porous media temperature has negligible effect on flame shape. Evaporation performance of n-heptane in low-temperature porous media is better than that of ethanol and dodecane. Ethanol and dodecane can evaporate completely with external heating and the flame is stable. Therefore, targeted heat management based on the characteristics of selected fuel is required to achieve stable and efficient combustion.