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A system that allows collection and analysis of all of the exhaust from individual engine cycles has been built. Its development and performance are described. The system was used to study the cyclic variability of a 0.7 liter direct injection diesel cylinder operating at 1500 rpm and an equivalence of 0.6. Particulate emissions exhibited the greatest variability. The cyclic variability (standard deviation) of particulate emissions associated with in-cylinder processes was found to be about 40% of the mean. The variability of NOx emissions that could be associated with in-cylinder processes was much lower, only about 6% of the mean. The variability of pressure development in the combustion process itself, as indicated by IMEP, was very low, less than 2% of the mean.

Soot formation and oxidation within the cylinder of a divided-chamber diesel engine have been studied experimentally and predicted analytically using a diesel combustion model. Experimental measurements of in-cylinder particle concentration were made using a unique sampling system which samples and quenches nearly the entire contents of the cylinder on a time scale of less than 1 ms. The experimental measurements are compared with predictions made using a stochastic combustion model coupled to an Arrhenius-type soot formation model, and 02 and OH soot oxidation models. Five engine conditions: low-load standard-timing (base case), high-load standard-timing, low-load advanced-timing, low-load standard-timing + EGR, and low-load standard-timing + 02, were examined experimentally, but only the first three were modeled.