Diesel Engine Smoke Reduction by Controlling Early Thermal Cracking Process and Activation Later Stage Combustion

Abstract

In this investigation, extensive soot reduction was attempted with two parallel approaches: blending of oxygenated fuel and generation of strong turbulence during the combustion process. In the early stage of usual diesel combustion, the droplets in the spray are thermally cracked to low boiling point components as C2 to C5 due to the shortage of oxygen, and these components result in the formation of soot. To control the thermal cracking process, the addition of oxygenated additives to the fuel was attempted. As a result, remarkable soot reduction was obtained by adding small amounts of oxygen to the fuel. To generate strong turbulence, a small chamber connected to the main combustion chamber was added and small amount of fuel were injected into the chamber, resulting in significant soot reduction. Additionally, a clearly apparent Nox reduction was obtained by the mixing control.