Crankcase Emission Contributions to PM for Two Tier 2 Line-Haul Locomotives

This paper documents the quantification and characterization of particulate matter (PM) emitted from two Tier 2 diesel locomotives, and the impact of crankcase ventilation (CCV) on PM emissions. Emission testing was performed on one General Electric (GE) model ES44DC locomotive, and one Electro-Motive Diesel (EMD) model SD70ACe. A semi-continuous organic carbon/elemental carbon (OC/EC) analytical procedure was used to collect and determine the OC and EC of PM. PM was also measured gravimetrically using Teflon membrane filters. Testing was performed for the locomotives in an unmodified configuration “with CCV”, and then again without the CCV included in the emissions measurements. Without CCV, the two-stroke SD70ACe brake specific filter-based PM and OC/EC PM, over the Line-haul Locomotive Duty Cycle (LHLDC), were reduced by approximately 15% to 16%, respectively, compared to testing with CCV. The 4-stroke ES44DC showed a reduction of 11% for the OC/EC PM which was mainly due to a reduction in OC PM. When crankcase emissions were not included, OC PM was reduced for nearly all throttle notches, and especially under high load conditions, although the differences were not always significant at a 95% confidence interval. With CCV, the relative OC portion of the Line-haul composite PM value for both locomotives was approximately 42–47%. Without CCV, the absolute brake-specific OC PM over the LHLDC was reduced by 30%, thereby reducing the relative OC portion to approximately 34–38%. This work showed that the OC PM fraction is significant for the locomotives tested, and controlling OC can lead to more than 40 percent reduction in PM. Furthermore, almost one-third of the OC PM was contributed by CCV, therefore better control of blow-by PM from both locomotive types can lead to a significant reduction in OC PM.