Evaluation of Heavy-Duty Diesel Vehicle Emissions During Cold-Start and Steady-State Idling Conditions and Reduction of Emissions from a Truck-Stop Electrification Program

Abstract

Cold-start and extended-idling emissions of carbon monoxide (CO), oxides of nitrogen (NOx) and particulate matter (PM) were measured from 24, class-8B, heavy-duty diesel vehicles (HDDV8B) using portable emission monitoring equipment. The ratio of nitrogen dioxide (NO2) to NOx and the ratio of PM2.5 to total PM were reported. Truck model years ranged from 1992 to 2004. All vehicles were tested in the field during summer and fall months under ambient environmental conditions at low (600-800 rpm) and high (1000 rpm) engine idling speeds with the truck cab air-conditioner operating at “on” and “off” modes. Sampling data thus obtained were used to generate typical average cold-start and extended-idling emission factors and were used to estimate potential emission reductions associated from using Truck Stop Electrification (TSE) Itechnology. Results indicated that cold-start emission rates, which were determined from the first 5-minutes of the cold-start period, were higher than the extended-idling emission rates by factors of 2.5 for CO, 1.5 for NOx and 1.7 for PM2.5. Overall, the extended-idling emission factors of the present study compared favorable to both the U.S Environmental Protection Agency (EPA) values that are recommended for State Implementation Plans (SIP) and average emission factors that were established from a previous review of the literature. In summary, the NOx emission rates were greater than those reported for EPA-SIP purposes and from the literature review by 23.5% and 17.4%, respectively. The PM2.5 emission rates observed in this study were less than those reported for EPA-SIP purposes by 3.8% and were greater than those reported in the literature by 6.3%, respectively. The average extended-idling emission factors for CO, NOx and PM2.5 were 64.5 g/hr, 167 g/hr and 3.51 g/hr, respectively. Electricity utilization and related emissions from TSE were calculated for a coal-fired power plant equipped with Selective Catalytic Reduction (SCR) technology for NOx removal and that meets New Source Performance Standards (NSPS) for NOx and PM2.5 emissions. In general, it was found that the cold-start emissions and the emissions from electricity were moderately small in comparison with the extended-idling emissions. Conversely, it was determined that the actual emission savings that could be associated with the TSE technology were 62.4 g/hr for CO, 158 g/hr for NOx and 3.19 g/hr for PM2.5. Finally, the corrected or actual emission reductions for CO, NOx and PM2.5 using a cold-start period for 5-minutes were approximately 3.2%, 5.0% and 10% less than the extended-idling emission rate, respectively