Measurement of Soot Particles in Combustion Chambers of Diesel Engines

Abstract

Diesel engines have been used in various fields because of their high thermal efficiency and application of low grade fuels. However it now becomes a great problem that their exhaust particles, i.e. soot, have considerable influence on environmental pollution.The process and mechanism of soot formation in diesel combustion have not necessarily been explained. The authors made an attempt to make clear the process of soot formation in a combustion chamber by optical means. The measuring method was conducted from the Lambert-Beer's law combined with the Mie's light scattering theory. It stands on the principle that extinction of light beam through particles, for instance soot in combustion chamber, is dependent on the wavelength and diameters of the particles. This multi-wavelength light extinction technique was proved to be practical by the measurement of polystyrene particles which were usually used as calibration aid in electron microphotography. Furthermore, it was applied to propane-air diffusion flames, and reasonable values of the volumetric density and the particle size distribution were obtained without difficulty. The authors confirm that the method is helpful to the combustion analysis because of its simple procedure and readiness for application.