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With increasingly stringent emission and fuel consumption regulations, fuel additives have been proved to have a huge role in energy conservation and emission reduction, a new type of fuel additive based on nitroparaffin has received worldwide attention. An experimental study was conducted with the aim of developing an understanding of the fuel additive’s effect on a 1.5L naturally aspirated PFI gasoline engine’s power performance, fuel economy, emissions and cylinder cleanliness. The results show that when fueled with fuel additive, engine power increased at full load condition. The commonly used working condition’s average fuel consumption decreased by 4.5% at fuel consumption contour map. For pollutant emissions, unburned hydrocarbons (HC), smoke (filter smoke number, FSN) decreased significantly, slightly higher nitrogen oxides (NOx) compared with no fuel additive. Furthermore, the use of fuel additive has a positive effect on elimination of carbon deposit in the cylinder.

A non-road diesel engine meeting China IV emission regulation was selected, the RMC and NRSC test procedures of the EU non-road Stage V emission regulation were run on the engine test bench. The emissions of particle number (PN) with particle sizes above 23 nm and 10 nm were tested simultaneously using direct exhaust sampling and full-flow dilution channel CVS dilution sampling equipment. The results showed that the emission characteristics of particulate matter above 23 nm and above 10 nm in the RMC test had the same trend, and the cumulative PN emissions were 1.9×1012 and 2.3×1012 for the whole test cycle, respectively. The PN23 values of dilution sampling were higher than those of direct sampling. The main reason for the difference in PN emission values at the same working modes in RMC and NRSC is the change in DPF capture efficiency caused by the different order of working modes and conditions.

A dump truck with a maximum designed total mass of 24500 kg was selected to measure the emission characteristics of pollutants and carbon dioxide (CO2) under fully-loaded and unloaded conditions at the same simulated road with different road slope, same driver and vehicle model by using the engine-inthe- loop methodology. The results show that driving at gradient road will result in an increase in power and total emissions. The brake specific emissions of gaseous pollutant and CO2 are lower at gradient road, while the brake emission of particle number are higher at gradient road. Road slope affects exhaust temperature so as to affect nitrogen oxide (NOx) emissions. Under unloaded conditions, long-slope conditions are more likely to cause an increase in NOx emissions.

Real driving emission characteristics of heavy-duty diesel vehicles with different technical routes were conducted by portable emission measurement system (PEMS) tests at different altitudes of 1400 meter and 2300 meter. Results show that the use of EGR will lead to increased particulate matter emissions but has little effect of NOx emissions. The EGR application exhibits a large effect on the PN emission but a little effect on NOx emission. PN emissions were strongly correlated with engine load during the PEMS test. The higher the engine load, the higher the PN emissions even at lower altitudes. There are large differences in PEMS test results even at the same altitude.

The emission characteristics under worldwide harmonized light vehicles test cycle (WLTC) was investigated for a 48V hybrid light-duty vehicle which carried a 2.0 L naturally aspirated engine on engine test bed after the WLTC cycle was converted to the corresponding engine transient cycle. The influence of electric heating catalyst on exhaust emission was analyzed. The results show that electric heating catalyst can effecively speed up the temperature rise rate then significantly decreases the exhaust emission. Electric heating has a more pronounced effect for ceramic carrier catalyst.

A dump truck with a maximum designed total mass of 25000 kg was selected to measure the real driving emission characteristics of pollutants and carbon dioxide (CO 2 ) under different altitudes of 0 meters, 800 meters and 1600 meters, with the same simulated road, driver and vehicle model but different vehicle loading of 0% and 40% by using the engine-in-the-loop (EIL) methodology. The results indicate that the EIL methodology can qualitatively and quantitatively analyze the impact of altitude on real driving emissions. The emissions of carbon monoxide (CO) and total hydrocarbons (THC) show a trend of first decreasing and then increasing with increasing altitude, while the emissions of particulate number (PN) show a trend of first sharply increasing and then slightly decreasing with increasing altitude. The variation pattern of nitrogen oxide (NOx) emissions with altitude is not significant. Under different altitude conditions, the specific emissions of CO 2 and THC decrease with increasing vehicle loading, while the specific emissions of PN and CO increase with increasing vehicle loading. However, the variation pattern of NOx emissions with vehicle loading is not obvious. In addition to being strongly correlated with exhaust temperature, the peak value of NOx emissions is highly correlated with road slope and vehicle acceleration. Cold start increases the specific emissions of CO 2 and pollutants, especially for PN and CO.