Methodology for the analysis of pollutant emissions from a city bus

In this work a methodology is proposed for measurement and analysis of gaseous emissions and particle size distributions emitted by a diesel city bus during its typical operation under urban driving conditions. As test circuit, a passenger transportation line at a Spanish city was used. Different ways for data processing and representation were studied and, derived from this work, a new approach is proposed. The methodology was useful to detect the most important uncertainties arising during registration and processing of data derived from a measurement campaign devoted to determine the main pollutant emissions. A HORIBA OBS-1300 gas analyzer and a TSI engine exhaust particle spectrometer were used with 1 Hz frequency data recording. The methodology proposed allows for the comparison of results (in mean values) derived from the analysis of either complete cycles or specific categories (or sequences). The analysis by categories is demonstrated to be a robust and helpful tool to isolate the effect of the main vehicle parameters (relative fuel-air ratio and velocity) on pollutant emissions. It was shown that acceleration sequences have the highest contribution to the total emissions, whereas deceleration sequences have the least.