Evaluation of an Enhanced Constant Volume Sampling System and a Bag Mini Diluter for Near Zero Exhaust Emission Testing

Abstract

<div class="htmlview paragraph">As automotive exhaust emission standards have become more stringent and emission control technologies have advanced over the years, accurately measuring the resulting near zero emissions has become increasingly difficult. To improve measurement accuracy, enhancements have been made to the conventional Constant Volume Sampling system (CVS) and to the analytical instrumentation</div> <div class="htmlview paragraph">This study included the evaluation of a CVS enhancement. Specifically, a prototype air filter was utilized to enhance the performance of a CVS by reducing non-methane hydrocarbons (NMHC) from dilution air at ambient temperature.</div> <div class="htmlview paragraph">Also incorporated into this study was the assessment of a Bag Mini-Dilute (BMD), a relatively new sampling system developed for measuring low-level vehicle emissions. The BMD can be used as an alternative to the CVS and has been approved for emission measurement by the United States Environmental Protection Agency (US EPA) and the California Air Resources Board (ARB.)</div> <div class="htmlview paragraph">Emissions from two super-ultra-low emission vehicles (SULEV) were tested to compare results obtained from a CVS, a CVS enhanced with a dilution air filter, and a BMD.</div>