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Silicon nitride (Si3N4) is a good candidate for a DPF substrate due to its excellent mechanical and thermal properties. The novel process for producing porous silicon nitride is established and fundamental characteristics of fabricated Si3N4 honeycomb were evaluated including mechanical/thermal properties and chemical stability against sulfuric acid and several kinds of chemicals. DPF characteristics in application such as pressure drop and soot regeneration behavior were investigated in diesel engine test bench. Numerical studies to evaluate stress in DPF during soot regeneration were also conducted.

This paper presents the characteristics of diesel spray with higher and unsteady injection pressure under an elevated pressure and temperature condition. For this purpose, a pneumatically actuated rapid-compression machine was developed, which has 120 mm bore combustion chamber. A Bosch type injection system was used and can realize the maximum injection pressure about 160 MPa. By using high-speed photography, the spray-tip penetration and the spray angle were measured. Under the non-evaporating condition, the penetrations of higher and normal injection pressure are almost the same, whereas, under the evaporating condition, those penetrations are not the same. Thus, the penetration of the normal injection pressure is affected by the ambient temperature, while that of the higher injection pressure is little affected by the evaporation. The same tendency was observed in the behavior of spray angle development.