Effects of Multiple Introduction of Fuel on Preflame Reactions in a Compression Ignition Engine

Cylinder pressure change caused by preliminary introduction of fuel in a CI engine, including introduction during the intake stroke, is measured in both a prechamber and an open chamber engine.

Values of ΔP and ΔU_F obtained are presented for variation of engine operating conditions such as engine speed, intake temperature, intake pressure, and compression ratio. Cetane number, voltaility, and quantity of preliminary fuel were also varied.

The results show that if the preliminary fuel is injected sufficiently early it passes through two distinct stages of exothermic reactions separated by an induction period during which the reaction rate is low. The preliminary fuel, by virtue of its longer residence time, completes the required sequence of physical and chemical transformations during the compression stroke.