INVESTIGATION OF THE SPRAY AND FLAME STRUCTURE CHARACTERISTICS OF JATROPHA BIODIESEL USING SIMPLEX AIRBLAST ATOMIZER

In the current scenario, the global warming and the climate change due to the emission liberated by conventional fossil fuel would show the adverse impact on the globe. The efforts for better solution to reduce carbon dioxide CO2 pollution emitted by transportation and other power producing units like thermal power plant, gas turbine units. Biodiesel, a renewable fuel is one of promising substitute for the above cause. Most of the countries are using bio-diesel up to 20% in compression ignition engines to reduce pollution and oil import bills. For good combustion in the oil furnace and gas turbine combustor, good mixture preparation, optimum spray, optimum flame length, cone angle and stable flame structure are the very essential requirements. Longer spray length causes wall wetting problem and smaller cone angle decrease fuel atomization. The flame instability causes fire extinguish problem.

In the present paper, the author’s investigate spray characteristic of a renewable fuel jatropha biodiesel and its diesel blends for continuous combustion applications (like gas turbine) using simplex airblast atomizer. Simplex air blast atomizer is the very good spray characteristics as compared to pressure type atomizer. Spray characteristics and flame structure such as sauter mean diameter, spray penetration length, spray cone angle, flame lift, flame width, flame height and inflame temperature are carried out at different operating conditions. The fuel injection pressure varied at step of 2 from 2 to 8 bars at constant fuel quantity 40 ml/min with atomizing air pressure of 7 bars. The AFR (atomizing air to liquid mass ratio) is maintained at 2 for good mixing. The results show that biodiesel provides slightly higher SMD with comparable atomization characteristics and short flame length with the base fuel diesel. Results also revealed that volumetric addition of biodiesel deceased spray cone angle and higher penetration length. Spray characteristics are found to improve by preheating fuel prior to the injection and also by increasing injection pressure. The results reveal that the increasing biodiesel proportion in diesel decreased flame height and increased in the flame lift causes unstable flame.