The following conclusions can be drawn for the highly preheated air turbulent diffusion propane flames.
Green flame color increases with decrease in oxygen concentration and increase in air-preheat temperature. This green
color is only observed for propane flame. Use of other fuel may not provide the same features. The observed yellow
flame color was found to increase with increase in temperature and oxygen concentration. At air preheat temperature
of up to 1000oC and O2 concentration from 5 to 15%, blue flame color predominates. The flame size increases with
decrease in oxygen concentration and increase in air temperature. The flame standoff distance from the nozzle exit
(ignition delay) was found to decrease with an increase in air preheat temperature. Two-stage combustion region was
observed under low oxygen concentration and high temperature air flames. The emission of NOx was significantly lower at
high temperatures and low oxygen concentration as compared to low temperatures and high oxygen concentration. Fuel
property has an effect on the flame thermal and chemical behavior. Flameless oxidation of the fuel (colorless flame) has
been observed under certain conditions. Thermal uniformity of flame is significantly enhanced with high temperature and
low oxygen concentration of air. Flame signatures can be significantly changed with change in fuel property, EGR, air
preheat temperature and O2 concentration in air. This allows one to design and develop highly preheated air combustion
technology for various applications. Calculated results with single-step model showed good qualitative agreement with
the experimental data. Main features of the HiTAC have been captured with the numerical code. Further numerical
studies on HiTAC will assist in understanding the flame structure, which are necessary for improving design and
wider application of high temperature combustion technology. Data are urgently needed for further understanding the
HiTAC Technology. This data should include fuel property effects as well as the fluid dynamics and chemical kinetics of
HiTAC. Challenges and potential of this technology presented here suggests significant advantages for further
understanding of HiTAC to various applications.