Browse Publications Technical Papers 2002-01-0048
2002-03-04

Studies on Enhanced CVS Technology to Achieve SULEV Certification 2002-01-0048

For the measurement of exhaust emissions, Constant Volume Sampling (CVS) technology is recommended by legislation and has proven its practical capability in the past. However, the introduction of new low emission standards has raised questions regarding the accuracy and variability of the CVS system when measuring very low emission levels.
This paper will show that CVS has the potential to achieve sufficient precision for certification of SULEV concepts. Thus, there is no need for the introduction of new test methods involving high cost.
An analysis of the CVS basic equations indicates the importance of the Dilution Factor (DF) for calculating true mass emissions. A test series will demonstrate that, by adjusting the dilution and using state of the art analyzers, the consistency of exhaust results is comparable with those of LEV concepts, measured with conventional CVS systems and former standard analyzers.
Blank tests and vehicle emission tests demonstrate that emissions at SULEV level can be measured with high accuracy.
Finally, this paper discusses the influence of individual components of the CVS system on exhaust results. It suggests an enhanced CVS system that detects SULEV limits with high precision.

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