Determination of Vehicle Emission Rates for Ammonia and Organic Molecular Markers Using a Chassis Dynamometer

Abstract

Stringent regulations have been implemented to address vehicle exhaust emissions and mitigate air pollution. However, the introduction of exhaust gas reduction devices, such as Three-Way Catalytic converters, has raised concerns about the generation and release of additional pollutants such as NH3. This study utilized a chassis dynamometer to investigate the characteristics of exhaust pollutants, including carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM), ammonia (NH3), organic carbon (OC), and elemental carbon (EC). The emissions were examined across various vehicle fuel types, namely liquefied petroleum gas, gasoline, and diesel (EURO4, EURO6), to assess their individual contributions to exhaust emissions. The results revealed significant variations in the emission levels of regulated pollutants (CO, HC, NOx, and PM) during driving, depending on factors such as engine technology, emissions control strategies, fuel type, and test cycle. Notably, NH3 emissions analysis according to driving mode indicated that gasoline vehicles exhibited the highest NH3 emissions, while diesel vehicles emitted negligible amounts. This observation can be attributed to the production of NH3 as a byproduct of catalytic reduction processes implemented by exhaust gas reduction devices targeting CO, HC, and NOx. In addition, EURO4 vehicles demonstrated higher emission levels of OC and EC compared with other fuel types. Furthermore, the presence of diesel particulate filters (DPFs) in diesel vehicles effectively reduced PM emissions. Moreover, this study investigated the emission characteristics of organic molecular markers within the organic carbon fraction, revealing distinct emission profiles for each vehicle and fuel type. These findings contribute to the identification of emission sources by discerning the primary components emitted by specific fuel types.