Correlation of Air Charge Temperature and Ignition Delay for Several Fuels in a Diesel Engine

A correlation between the ignition delay, based on the start of pressure rise due to combustion, and the mean air charge temperature has been obtained for diesel, “CITE,” and gasoline fuels.

The experimental work was done on a single cylinder open combustion chamber research engine. The intake air temperature was varied over a wide range from atmospheric to about 750 F.

The experimental data indicated that the best correlation of the ignition delay and the reciprocal of the absolute temperature is of an exponential form. The apparent activation energy for the three fuels was found to have a straight line relationship with the cetane number of the fuel.