Real-world gaseous emission characteristics of natural gas heavy-duty sanitation trucks

As compared to conventional diesel heavy-duty vehicles, natural gas vehicles have been proved to be more eco-friendly due to their lower production of greenhouse gas and pollutant emissions, which are causing enormous adverse effects on global warming and air pollution. However, natural gas vehicles were rarely studied before, especially through on-road measurements. In this study, a portable emission measurement system(PEMS) was employed to investigate the real-world emissions of nitrogen oxides(NOx)(nitrogen monoxide(NO), nitrogen dioxide(NO)), total hydrocarbons(THC), carbon monoxide(CO), and carbon dioxide(CO) from two liquified natural gas(LNG) China V heavy-duty cleaning sanitation trucks with different weight. Associated with the more aggressive driving behaviors, the vehicle with lower weight exhibited higher CO(3%) but lower NOx(48.3%)(NO2(78.2%) and NO(29.4%)), CO(44.8%), and THC(3.7%) emission factors. Aggressive driving behaviors were also favorable to the production of THC, especially those in the medium-speed range but significantly negative to the production of CO and NO, especially those in the low-speed range with high engine load. In particular, the emission rate ratio of NO/NO decreased with the increase of speed/scaled tractive power in different speed ranges.