Diesel and CNG Transit Bus Emissions Characterization by Two Chassis Dynamometer Laboratories: Results and Issues

1999-01-1469

05/03/1999

Event
International Fuels & Lubricants Meeting & Exposition
Authors Abstract
Content
Emissions of six 32 passenger transit buses were characterized using one of the West Virginia University (WVU) Transportable Heavy Duty Emissions Testing Laboratories, and the fixed base chassis dynamometer at the Colorado Institute for Fuels and High Altitude Engine Research (CIFER). Three of the buses were powered with 1997 ISB 5.9 liter Cummins diesel engines, and three were powered with the 1997 5.9 liter Cummins natural gas (NG) counterpart. The NG engines were LEV certified. Objectives were to contrast the emissions performance of the diesel and NG units, and to compare results from the two laboratories. Both laboratories found that oxides of nitrogen and particulate matter (PM) emissions were substantially lower for the natural gas buses than for the diesel buses. It was observed that by varying the rapidity of pedal movement during accelerations in the Central Business District cycle (CBD), CO and PM emissions from the diesel buses could be varied by a factor of three or more. The driving styles may be characterized as aggressive and non-aggressive, but both styles followed the CBD speed command acceptably. PM emissions were far higher for the aggressive driving style. For the NG fueled vehicles driving style had a similar, although smaller, effect on NOx. It is evident that driver habits may cause substantial deviation in emissions for the CBD cycle. When the CO emissions are used as a surrogate for driver aggression, a regression analysis shows that NOx and PM emissions from the two laboratories agree closely for equivalent driving style. Implications of driver habit for emissions inventories and regulations are briefly considered.
Meta TagsDetails
DOI
https://doi.org/10.4271/1999-01-1469
Pages
14
Citation
Clark, N., Gautam, M., Rapp, B., Lyons, D. et al., "Diesel and CNG Transit Bus Emissions Characterization by Two Chassis Dynamometer Laboratories: Results and Issues," SAE Technical Paper 1999-01-1469, 1999, https://doi.org/10.4271/1999-01-1469.
Additional Details
Publisher
Published
May 3, 1999
Product Code
1999-01-1469
Content Type
Technical Paper
Language
English