Multidimensional Correlation Study Using Linear Regression of PM and NOX for Heavy Duty Diesel Vehicles 2005-01-1618
When heavy-duty truck emissions rates are expressed in distance-specific units (such as g/mile), average speed and the degree of transient behavior of the vehicle activity can affect the emissions rate. Previous one-dimensional studies have shown some correlation of distance-specific emissions rates between cycles. This paper reviews emissions data sets from the 5-mode CARB Heavy Heavy-Duty Diesel Truck (HHDDT) Schedule, the Heavy Duty Urban Dynamometer Driving Schedule (UDDS) and an inspection and maintenance cycle, known as the AC5080. A heavy-duty chassis dynamometer was used for emissions characterization along with a full-scale dilution tunnel. The vehicle test weights were simulated at 56,000 lbs. Two-dimensional correlations were used to predict the emissions rate on one mode or cycle from the rates of two other modes or cycles. Oxides of Nitrogen (NOx) and Particulate Matter (PM) emissions were the two components of emissions which were of interest, and they were reviewed in units of g/mile. The multidimensional analysis using two cycles yielded better predictive correlations for the emissions than single cycle correlations published previously. The UDDS schedule yielded the highest distance-specific emissions and it showed similar emissions as the combination of the Cruise mode and Transient mode of the HHDDT.