Investigation of a new design of inverse diffusion flame burner

Abstract EN

Diffusion flame are used in a wide range instead of premixed flame because it is more safe, although it produces more emissions and is less efficient than the premixed flame.

Some applications require unconfined diffusion flames which are known to be worse than confined ones, from the point of view of efficiency and the relatively large amount of combustion air requirements.

Therefore, the development of unconfined diffusion flames to improve its efficiency, emissions and air power consumption becomes know necessarily required.

The inverse diffusion flame introduces a small amount of air (high equivalence ratios) in the center of flame and the fuel is at the circumference.

The fuel is diffused inward to in and form good mixing with the central air, meanwhile the outer atmospheric air can diffuse in the fuel to help substitute the deficiency of central air and hence improve the combustion efficiency.

It has been found that one of the main factors affecting the inverse diffusion flame performance is the contact area between fuel and air.

The present design of a novel inverse diffusion flame burner increases the contact area to maximum between the central air and the outer fuel.

The new design uses consecutive slots (rectangular shaped) i.e.

fuel-air-fuel instead of coaxial circular burner.

Many measurements were carried out on the new burner (slot) and the conventional one (coaxial) including mainly, the axial temperature, the flame appearance, and the axial gas analysis.

The comparison between the new and the conventional burners reveals that the axial flame temperature is about 400 oC higher than that of coaxial one, also the entrainments area is increased, and the combustion efficiency is improved which is indicated the increase of CO2 and the reduction of O2 percentages in the axial gas analysis.