Crankcase Particulate Emissions from Diesel Engines

In 2007, US EPA implemented the rule that the crankcase emissions be added to the tailpipe emissions to determine the total emissions from a diesel engine if the crankcase were not closed, but few data exist to quantify crankcase emissions from earlier model diesel engines. This paper presents the results of a study on the measurement of the size distribution and number concentration of particulate matter (PM) emitted from the crankcase vents from four different diesel engines under different engine speeds and loads. The engines used in the study were a 1992 Detroit Diesel Series 60, a 1996 Caterpillar 3406E, a 1997 Cummins B5.9 and a 1995 Mack E7-400. The Detroit Diesel engine was tested on an engine dynamometer and crankcase and tailpipe particulates were observed at varying engine speeds and loads. The other three engines were mounted in vehicles, and crankcase PM was observed at several engine speeds with no external load. Overall, the study showed that the size distribution and number concentration profiles of crankcase particulate emissions differed substantially from engine to engine. All three trucks examined showed a similar reduction in crankcase emissions as the engine warmed following a cold start, but an idling engine on a dynamometer differed in behavior. Also, for elevated idle speeds with a warm engine, strongly bimodal distributions were seen for all three trucks.