Effects of Engine Speed and Accessory Load on Idling Emissions from Heavy-Duty Diesel Truck Engines

Abstract

A nontrivial portion of heavy-duty vehicle emissions of NOx and particulate matter (PM) occurs during idling. Regulators and the environmental community are interested in curtailing truck idling emissions, but current emissions models do not characterize them accurately, and little quantitative data exist to evaluate the relative effectiveness of various policies. The objectives of this study were to quantify the effect of accessory loading and engine speed on idling emissions from a properly functioning, modern, heavy-duty diesel truck and to compare these results with data from earlier model year vehicles. It was found that emissions during idling varied greatly as a function of engine model year, engine speed, and accessory load conditions. For the 1999 model year Class 8 truck tested, raising the engine speed from 600 to 1050 rpm and turning on the air conditioning resulted in a 2.5-fold increase in NOx emissions in grams per hour, a 2-fold increase in CO2 emissions, and a 5-fold increase in CO emissions while idling. On a grams per gallon fuel basis, NOx emissions while idling were approximately twice as high as those at 55 mph. The CO2 emissions at the two conditions were closer. The NOx emissions from the 1999 truck while idling with air conditioning running were slightly more than those of two 1990 model year trucks under equivalent conditions, and the hydrocarbon (HC) and CO emissions were significantly lower. It was found that the NOx emissions used in the California Air Resources Board's (CARB) EMFAC2000 and the U.S. Environmental Protection Agency's (EPA) MOBILE5b emissions inventory models were lower than those measured in all of the idling conditions tested on the 1999 truck.

Idle Emissions from Heavy-Duty Diesel Vehicles: Review and Recent Data

“…Elevating the engine speed from 600 to 1100 rpm with the A/C increased the CO 2 , NO x , and PM emissions by 225%, 284%, and 100%, respectively. Brodrick et al 7 also observed the effect of engine speed with A/C on idle emissions and found that elevating the engine speed from 600 to 1050 rpm (with A/C on in both cases) resulted in a corresponding increase in idle CO, NO x , and CO 2 emissions by ϳ460%, 53%, and 90%, respectively. A/C load depends on temperature, humidity, and heat load and, therefore, may not be repeatable.…”

“…Diesel trucks, on average, emitted 10.2 g/hr of total HCs (THC), 70.98 g/hr of CO, 84.96 g/hr of NO x , and 1.8 g/hr of PM during idling, whereas CNG vehicle idle emissions averaged 86.1 g/hr of THC, 67.14 g/hr of CO, 16.02g/hr of NO x , and 0.18g/hr of PM. Brodrick et al 7 examined the effects of engine speed and accessory loading on idle emissions on a 1999 model year Freightliner truck powered by a 450 horsepower engine. Increasing the engine speed from 600 to 1050 revolutions per minute ([rpm] with air conditioning on in both cases) resulted in increased emissions of CO, NO x , and CO 2 emissions by ϳ460%, 53%, and 90%, respectively.…”

Heavy-duty, off-road diesel engine low-load particle number emissions and particle control

“…Carbon monoxide and gaseous hydrocarbon emissions are notable at idle compared to those at operating loads (Tong, Hung, and Cheung, 2000;Merritt et al, 2005;Brodrick et al, 2002). Idle exhaust hydrocarbon emissions contain noncombusted fuel compounds and the volatile organics dominate the particle mass emissions.…”

Benefits from GIS Based Modelling for Municipal Solid Waste Management

“…Using GIS 3D modelling in the island of Santo Antao, Republic of Cape Verde, an area with complex topography, they achieved up to 52% fuel savings compared to the shortest distance, even travelling a 34% longer distance. Nevertheless, most of the previous work relating to optimal routing for solid waste collection is based on the minimisation of the travelled distance and/or time (Apaydin & Gonullu, 2007;Lopez et al, 2008), which is considered a sufficient calculator parameter for fuel consumption and emissions minimisation in flat relief (Brodrick et al, 2002). Sahoo et al (2005) presented a comprehensive route-management system, the WasteRoute for the optimal management of nearly 26000 collection and transfer vehicles that collect over 80 million tons of garbage every year for more than 48 states of USA.…”

“…In the current waste collection system, 714 bins are located in Sector 1 (Fig.3), of which 501 are mechanically collected, with total capacity of 157,000 L. The content of the rest is manually transferred to the mechanically collected ones by the extra worker mentioned above. Since Sector 1 is rather flat (mean elevation ~ 50 m) it is assumed that fuel consumption and emissions are linearly related to collection time (Brodrick et al, 2002). For waste collection purposes Sector 1 is divided into two sub-sectors both served by one waste collection vehicle.…”