Exhaust emissions of buses LNG and Diesel in RDE tests

Abstract

The article compares the exhaust emissions in road conditions of city buses: LNG and Diesel. Both buses met the Euro VI exhaust emission norm. The current strong drive to diversify fuels in Poland and the creation of a large gas port in Swinoujście for LNG imports creates an excellent opportunity to use this fuel, also in road transport. Therefore, the attempt to identify the emission in operation, in first place possible applications, i.e. an LNG bus, comparatively with the emission of a Diesel bus. The operational research carried out concerned such a bus and has not yet been carried out in the country, hence their innovation, also methodological. The conducted research, in particular, was aimed at verifying differences in exhaust emissions of carbon dioxide and nitrogen oxides. The study was carried out on one urban bus route performing trips on consecutive days in similar environmental conditions. The performed tests were not strictly type approval tests but only used for comparative purposes. Hence, it was necessary to determine the compliance factor for the relevant exhaust gas substances, with the use of an evaluation algorithm based on measurement windows. Based on these results, the assumption regarding compliance with the emission requirements for the tested buses was verified in real traffic conditions. The exhaust emission values (emission indicators) determined in this way did not exceed the permissible emission limit values for carbon monoxide, while for nitrogen oxides and non-methane hydrocarbons certain exceedances were found.