This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Development of Continuous Dilution Factor for CVS Emissions Sampling and Calculation
ISSN: 0148-7191, e-ISSN: 2688-3627
Published November 12, 2001 by SAE International in United States
Annotation ability available
During the last three decades, the emissions measurement system for heavy duty vehicle testing has employed a Constant Volume Sampler (CVS) system to continuously measure the pollutant concentrations in the dilution tunnel. Subsequent gaseous emissions calculation methods were based on Code of Federal Regulations, Title 40 (CFR-40) in which a formula for calculating dilution factor (DF) was specified to account for background pollutants. However, it is recognized that due to the mechanism of the CVS system, the dilution factor varies from a constant during a test cycle. The DF calculation technique can introduce error in the emissions data, but the magnitude of potential error is small relative to the current emissions standards. However, as the engine technologies improve and cleaner burning fuels are adopted in the near future, the pollutant concentrations from engines will approach those in ambient air. In that case, the current calculation method in CFR-40 can result in errors that are relatively large. In this study, a new approach was developed to calculate instantaneous DF during a test cycle for natural gas vehicles equipped with oxygen sensors. This new method has improved the accuracy of emissions measurement and calculation, which would be desirable when testing vehicles with near zero emissions. The instantaneous dilution factor is also used to calculate the emissions concentrations in the raw engine exhaust prior to being diluted. The emissions characteristics at different engine operation modes were analyzed for natural gas engines and the measures for reducing emissions were also discussed.
CitationFu, J., Wang, W., and Lyons, D., "Development of Continuous Dilution Factor for CVS Emissions Sampling and Calculation," SAE Technical Paper 2001-01-2815, 2001, https://doi.org/10.4271/2001-01-2815.
SAE 2001 Transactions Journal of Commercial Vehicles
Number: V110-2; Published: 2002-09-15
Number: V110-2; Published: 2002-09-15
- Wang, W. G. Lyons D. W. Clark N. N. Gautam M. Norton P. “Emissions from Nine Heavy Trucks Fueled by Diesel and Biodiesel Blend without Engine Modification” Environmental Science & Technology 34 2000 933 939
- Wang, W. G. Lyons, D. Clark, N Luo, J. D. “Energy Consumption Analysis of Heavy-Duty Vehicles for Transient Emissions Evaluation on Chassis Dynamometer,” Institute of Mechanical Engineers, Journal of Automobile Engineering 213 1999 205 214
- Wang, W. G. Clark, N. Lyons, D. Yang R. Gautam M. “Emissions Comparisons from Alternative Fuel Buses and Diesel Buses with a Chassis Dynamometer Testing Facility” Environmental Science & Technology 31 11 3132 3137 1997
- Wang, W. G. Gautam, M. Sun, X. “Emission Comparisons of twenty-six Heavy-duty Vehicles Operated on Conventional and Alternative Fuels” SAE Paper 932952 , SAE Transactions 102 Journal of Commercial Vehicles 566 575
- Wang, W. G. Clark, N. N. Lyons, D. W. Gautam M. “Emissions from Buses with DDC 6V-92 Engines Powered by Methanol, Ethanol and Diesel” 12th International Symposium on Alcohol Fuels Beijing, China Sept. 21-24 1998
- Messer, J. Clark, N. Lyons, D. “Measurement Delay and Modal Analysis for a Heavy Duty Transportable Emissions Testing Laboratory” SAE Paper 950218 1995
- Protection of Environment 1994
- Taylor, C. “The Internal Combustion Engine in Theory and Practice” The MIT Press Cambridge, MA 1985
- “Engine Emissions and Emissions Measurement” SAE SP-1161 1996
- Beaumont, A. “Signal Reconstruction Techniques for Improved Measurement of Transient Emissions” SAE Paper 900233 1990
- Austin, T. Caretto, L. “Improving the Calculation of Exhaust Gas Dilution During Constant Volume Sampling” SAE Paper 980678 1998
- Wiers, Ward W. Scheffler, C.E. “Carbon Dioxide Tracer Technique for Modal Mass Exhaust Emission Measurements” SAE Paper 720162 1972