Coaxial Flames Research Articles

The atomization and burning of liquid fuel sprays

The purpose of this research paper is to investigate the energy valorization from the pyrolysis of waste tires using coaxial continuous flame burners. For such an investigation, both the Tire Pyrolysis Oil (TPO) along with its blend (B1) with light diesel oil (LDO) were prepared, physically and chemically characterized, and then combusted in coaxial burners. To distinguish the spectral emission peaks, for the vaporization and combustion zone and the hot recirculation zone of the produced flame, flame spectroscopy techniques were utilized. The mass-specific emission indices and the axial inflame temperatures were used as indicators of the flame radiation intensity in the flame zones. The coaxial flame was inspected for excess air factors of 1.33, 1.04, and 0.9. In the study, a higher radiation intensity of TPO/LDO blend flame was recognized in the B1 flame length which was taller than that of LDO by 48% at λ=1.33. Furthermore, a decrease in CO emissions levels was also noticed in the combustion of waste tire pyrolysis oil and B1 by an average of 4%–12% compared to that from HDO, and the NOx emissions were also reduced by 8.5%–26%. The highest axial inflame temperature of 1,205 °C was recorded for TPO at condition λ=0.9, where the presence of oxygen molecules in fuel helps flame improvements.

Flame attachment zone of laminar, premixed methane-air flames

The interaction between inner and external coaxial flames is experimentally investigated in detail. The minimum equivalence ratio t of CH4-air premixtures (test premixtures) for complete combustion is measured as a function of the flow rate by the use of a small pilot flame whose equivalence ratio, p is equal to unity or less. The minimum t is dependent upon p and the flow rate of the test premixture. The effects of radial and axial separations of the two flames are also investigated with the use of three types of burner ports. The existence of diffusive and convective mixing of the two flows on a coaxial burner is proved. The magnitude of the mixing is estimated by a numerical calculation. A small amount of mixing plays an important role in stabilizing the flame in a highspeed flow of the lean premixture. It is concluded that the use of a coaxial burner for the measurements of the flammability limits is invalid.This paper also discusses the merit of simple coaxial burners without any thermal feedback or recirculating flow flow for lean premixture combustions. The overall minimum equivalence ratio attained by the present experiments is 0.6 at a mean flow velocity of 5.3 m/sec.

Material Transfer in Turbulent Gas Streams - A Coaxial Flame.

Material Transfer in Turbulent Gas Streams - A Coaxial Flame.