Factor Analysis of HC and CO Formation in a PCI engine

Abstract

The mechanism of HC formation in PCI may be different from that in conventional direct-injection diesel becuase injection timing of a PCI engine is considerably earlier than that of a conventional diesel engine.
In this study, the characteristics of HC and CO emissions in a PCI engine were investigated by changing combustion chamber geometry(cavity diameter), topland volume, injection timing and piston surface temperature in experiments. At the same time, the simulations of spray and air-fuel mixture formation were conducted by using GTT code. The relationship between HC and CO formations and mixture distribution was tried to clarify. As a result, HC and CO emissions in PCI engine are depended strongly on the fuel distribution in the cylinder and would increase if fuel extruded out of cavity and entered the squish area.