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Comparative Studies of Exhaust Emission from Three City Buses Under Real Traffic Conditions, One with LNG, the Other with CI Engine and Hybrid Bus
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 15, 2020 by SAE International in United States
There is a growing appreciation for using buses powered by alternative fuels in urban transport. Considered as such are city bus with engines fueled with LNG and Hybrid bus. This article, as shown above, provides a comparison of road exhaust emissions from three city buses: one with a CI engine fueled with diesel fuel, and the other with a SI engine fueled with LNG and Hybrid bus. Both vehicles (CI and LNG) conformed to Euro VI emission standard (Hybrid bus EEV), and the tests were carried out in real traffic conditions. Equivocal opinions about differences in emissions from those types of buses, among others – CO2 and NOX emissions, were the under-lying cause of the tests. The comparative study was carried out along the same urban routes during bus trips over the following days in similar traffic conditions. Exhaust road emission was determined based on the vehicle's curb weight and route length, and operating fuel consumption. Also, the study was consistent with the most requirements laid down in the regulation regarding estimates of fuel consumption consistency ratio during road tests from heavy-duty vehicles. For that reason, it was necessary to determine the conformity factor for relevant exhaust sub-stances in exhaust gases in window functions, based on which the assumption on the fulfilment of emission requirements for three buses in real traffic conditions was verified. The values thus established of emissions of exhaust substances from exhaust gases in tested city buses did practically not exceed permissible limit CO values, while for NOx and NMHC there are some exceedances. The tests were not type approval.