World-harmonized Light-duty Test Cycle Research Articles

Chemical characteristics analysis of automobile exhaust particles and the method for evaluating its ecological effect

Automobile exhaust has become the main source of atmospheric particulate matter with the increase in the number of automobiles. Automobile exhaust particles (AEPs) discharged into the atmosphere can enter the aquatic environment through atmospheric deposition, rain runoff, leaching, drainage water and urban sewage and further affect aquatic organisms. However, there is no comprehensive theory and method to evaluate the ecological effects of AEPs on aquatic environment. The new European driving cycle (NEDC) and the world harmonized light-duty test cycle (WLTC) were used to analyze the ecotoxicity of AEPs. The SUV gasoline, SUV hybrid and sedan gasoline under WLTC were used for further analysis. The chemical characteristics of AEPs were analyzed, and the ecotoxicity of AEPs on aquatic organisms was studied with Vibrio fischeri and Danio rerio as test organisms. The ecological effect of AEPs was studied through species sensitivity distribution based on interspecies correlation estimation (ICE) models. The results showed that (ⅰ) polycyclic aromatic hydrocarbons (PAHs) were the main organic substances in AEPs. The total concentrations of PAHs in AEPs measured under the NEDC and WLTC were 237.4 and 159.8 mg kg−1, respectively, and the EC50 values for V. fischeri measured under the NEDC and WLTC were 42.02 and 47.05 mg L−1, respectively. (ⅱ) Total heavy metal concentrations in AEPs from SUV gasoline, SUV hybrid, and sedan gasoline were 197.52, 104.86, and 89.68 mg kg−1, respectively, and the LC50 values for D. rerio were 3.22, 4.46 and 5.62 mg L−1. Cu and Mn were the main toxic heavy metals in AEPs. (ⅲ) The PNEC values of AEPs from SUV gasoline, SUV hybrid and sedan gasoline were 0.57, 0.83 and 1.02 mg L−1, respectively. This exploratory study can provide technical information on water ecological safety assessment for determining the impact of AEPs on the surface water environment and for further improving automobile exhaust emission standards.

Trap efficiency of exhaust gas pollutants in microporous sorbents under representative driving conditions

The objective of this study is to develop a Neutral Air Quality Impact Vehicle (NAQIV) using a system able to reduce the tailpipe emissions of a gasoline powertrain engine. A possible configuration is a bypass in the exhaust, close to the tailpipe, that stores pollutants during the cold start phase when most emissions occur. For this purpose, adsorption efficiencies of commercial sieved powders Activated Carbon (AC), and zeolites (BEA, MFI) were screened at trap temperatures of 25, 50, and 150 °C using two different exhaust gas compositions. These compositions are obtained from two different phases of the World Harmonized Light-Duty Test Cycle (WLTC): the first 100 s after the engine start, and the first “5 km” after a cold start, the latter being representative of typical emissions of an automotive vehicle on an average trip in urban areas. The aim is also to provide sorption capacity not only in respect to the conventional pollutants (CO, NOx, CO2), and the most common NMHCs present in the exhaust gas (toluene, i-pentane, n-pentane, acetylene, ethylene, and methane), but also towards unregulated pollutants such as NH3, CH4 and N2O (to be introduced in Euro 7 regulations). The experimental results reveal a superior performance of AC NMHCs adsorption (and particularly toluene, n-pentane and i-pentane) which is not affected by the presence of other pollutants, but is negatively impacted by rising temperature and flow gas composition. Among zeolites, only Cu/Beta and Cu/ZSM-5 display moderate adsorption capacity of NH3, NMHCs and NO. In particular, the adsorption of ethylene and acetylene over Cu/ZSM-5 is strongly promoted at lower H2O concentrations. Finally, desorption profiles of each pollutant were generated through Temperature Programmed Desorption (TPD) experiments, unraveling sorbate-sorbent interactions.

Ammonia emissions from China-6 compliant gasoline vehicles tested over the WLTC

Ammonia emissions cause several negative impacts on the quality of air, water and soil, while secondary ammonia formed on three-way catalysts (TWCs) of gasoline vehicles has not been sufficiently investigated, especially in the developing countries. In this paper, tailpipe ammonia emissions from seven China-6 certified, low-mileage gasoline vehicles were measured over the World Harmonized Light-duty Test Cycle (WLTC). The results demonstrated that ammonia emissions from the seven test vehicles ranged from 0.65 ± 0.38 mg/km to 8.01 ± 3.12 mg/km. A comparison with the emission factors reported in other research indicates that these China-6 certified vehicles emitted similar or less ammonia emissions compared to the vehicles certified to older EU and federal regulations. The ammonia emissions from the test vehicles showed very weak linkage with their engine or transmission technologies. For all the test vehicles, the vast majority of ammonia emissions were emitted within the engine warm-up period due to already lighted-off catalysts but still enriched air/fuel mixtures. No ammonia emissions were noticed within any engine-start events. The masses of ammonia-converted ammonium salts were estimated assuming that all the tailpipe ammonia emissions will transform into ammonium nitrate and ammonium sulfate, and compared to the primary PM emissions measured with filters. The masses of salts were drastically higher than the primary PM, which underscored the significance of vehicle-related ammonia emissions as a key ambient PM contributor.

Impact of cold temperature on Euro 6 passenger car emissions.

Hydrocarbons, CO, NOx, NH3, N2O, CO2 and particulate matter emissions affect air quality, global warming and human health. Transport sector is an important source of these pollutants and high pollution episodes are often experienced during the cold season. However, EU vehicle emissions regulation at cold ambient temperature only addresses hydrocarbons and CO vehicular emissions. For that reason, we have studied the impact that cold ambient temperatures have on Euro 6 diesel and spark ignition (including: gasoline, ethanol flex-fuel and hybrid vehicles) vehicle emissions using the World-harmonized Light-duty Test Cycle (WLTC) at −7 °C and 23 °C. Results indicate that when facing the WLTC at 23 °C the tested vehicles present emissions below the values set for type approval of Euro 6 vehicles (still using NEDC), with the exception of NOx emissions from diesel vehicles that were 2.3–6 times higher than Euro 6 standards. However, emissions disproportionally increased when vehicles were tested at cold ambient temperature (−7 °C). High solid particle number (SPN) emissions (>1 × 1011 # km−1) were measured from gasoline direct injection (GDI) vehicles and gasoline port fuel injection vehicles. However, only diesel and GDI SPN emissions are currently regulated. Results show the need for a new, technology independent, procedure that enables the authorities to assess pollutant emissions from vehicles at cold ambient temperatures.Harmful pollutant emissions from spark ignition and diesel vehicles are strongly and negatively affected by cold ambient temperatures. Only hydrocarbon, CO emissions are currently regulated at cold temperature. Therefore, it is of great importance to revise current EU winter vehicle emissions regulation.

On-road measurement of NH3 emissions from gasoline and diesel passenger cars during real world driving conditions

NH3 is a precursor of PM2.5 which deteriorates urban air quality, affects human health and impacts the global radiation budget. Since vehicles are important sources of NH3 in urban areas, we have satisfactorily studied the possibility of measuring NH3 emissions from gasoline and SCR-equipped diesel light-duty vehicles during real driving on-road operation using a portable FTIR. The performance of the portable FTIR resulted to be comparable to that of a laboratory-based FTIR during a series of experiments performed in the Vehicle Emission Laboratory (VELA) using the World-harmonized Light-duty Test Cycle (WLTC). Higher on-road NH3 emission factors were obtained for the gasoline vehicle than for the diesel. High NOx emissions were measured from the diesel vehicle, indicating a low efficiency of the DeNOx system, SCR. On-road NH3 emission factors were ∼2 times lower than during the laboratory tests at 23 °C for both vehiclesNH3 emissions were not observed for the diesel vehicle during cold start operation. However, NH3 cold start emissions from the gasoline vehicle were up to 2 orders of magnitude higher than during the entire road trips, ranging from 45 to 134 mg km−1. Cold start emissions are of paramount importance as they commonly take place in urban areas. Hence, future urban reductions in PM2.5 might need to take into consideration the introduction of NH3 emissions limits for passenger cars.

Euro 6 Unregulated Pollutant Characterization and Statistical Analysis of After-Treatment Device and Driving-Condition Impact on Recent Passenger-Car Emissions.

This study aims to measure and analyze unregulated compound emissions for two Euro 6 diesel and gasoline vehicles. The vehicles were tested on a chassis dynamometer under various driving cycles: Artemis driving cycles (urban, road, and motorway), the New European Driving Cycle (NEDC) and the World Harmonized Light-Duty Test Cycle (WLTC) for Europe, and world approval cycles. The emissions of unregulated compounds (such as total particle number (PN) (over 5.6 nm); black carbon (BC); NO2; benzene, toluene, ethylbenzene, and xylene (BTEX); carbonyl compounds; and polycyclic aromatic hydrocarbons (PAHs)) were measured with several online devices, and different samples were collected using cartridges and quartz filters. Furthermore, a preliminary statistical analysis was performed on eight Euro 4-6 diesel and gasoline vehicles to study the impacts of driving conditions and after-treatment and engine technologies on emissions of regulated and unregulated pollutants. The results indicate that urban conditions with cold starts induce high emissions of BTEX and carbonyl compounds. Motorway conditions are characterized by high emissions of particle numbers and CO, which mainly induced by gasoline vehicles. Compared with gasoline vehicles, diesel vehicles equipped with catalyzed or additive DPF emit fewer particles but more NOx and carbonyl compounds.

Impact of driving style and road grade on gaseous exhaust emissions of passenger vehicles measured by a Portable Emission Measurement System (PEMS)

Motivated by the upcoming Euro-6c regulation including Real Driving Emissions (RDE), the present study addresses the impact of different driving styles and route characteristics on on-road exhaust emissions. Gaseous emissions of two Diesel test vehicles (Euro-5 and Euro-6) were measured using a Portable Emission Measurement System (PEMS) on an RDE compliant test route.The driving parameters relative positive acceleration (RPA), mean positive acceleration (MPA) and v∗apos95 allowed a favorable classification of different driving styles. The comparison of driving parameters for normal PEMS trips with reference data obtained from the World harmonized Light-duty Test Cycle (WLTC) and from Field Operational Tests (FOT) indicated a good representation of normal driving. Severe driving led to elevated CO2 and NOx emissions as compared to normal trips while CO and HC did not allow a distinct classification of different driving styles.Route characteristics of four different routes were investigated applying the parameter cumulated altitude gain using Google Elevation data. The distance specific NOx emissions were in the same range for trips with comparable driving dynamics on routes with similar cumulated altitude gain. Based on repetitive measurements the road grade was calculated within 100m segments. CO2 and NOx emissions measured by a PEMS showed a linear increase with road grade. Larger emissions at higher road grades could be explained by more frequent high engine load points. In this study cumulated altitude gain and road grade were directly correlated to emissions measured by the PEMS and the step from 0 to 5% road grade led to a CO2 increase of 65–81% and a NOx increase of 85–115%.

Unregulated emissions from light-duty hybrid electric vehicles

The number of registrations of light duty hybrid electric vehicles has systematically increased over the last years and it is expected to keep growing. Hence, evaluation of their emissions becomes very important in order to be able to anticipate their impact and share in the total emissions from the transport sector. For that reason the emissions from a Euro 5 compliant hybrid electric vehicle (HV2) and a Euro 5 plug-in hybrid electric vehicle (PHV1) were investigated with special interest on exhaust emissions of ammonia, acetaldehyde and ethanol. Vehicles were tested over the World harmonized Light-duty Test Cycle (WLTC) at 23 and −7 °C using two different commercial fuels E5 and E10 (gasoline containing 5% and 10% vol/vol of ethanol, respectively). PHV1 resulted in lower emissions than HV2 due to the pure electric strategy used by the former. PHV1 and HV2 showed lower regulated emissions than conventional Euro 5 gasoline light duty vehicles. However, emissions of ammonia (2–8 and 6–15 mg km−1 at 22 and −7 °C, respectively), ethanol (0.3–0.8 and 2.6–7.2 mg km−1 at 22 and −7 °C, respectively) and acetaldehyde (∼0.2 and 0.8–2.7 mg km−1 at 22 and −7 °C, respectively) were in the same range of those recently reported for conventional gasoline light duty vehicles.

On-road particle number measurements using a portable emission measurement system (PEMS)

Abstract In this study the on-road particle number (PN) performance of a Euro-5 direct-injection (DI) gasoline passenger car was investigated. PN emissions were measured using the prototype of a portable emission measurement system (PEMS). PN PEMS correlations with chassis dynamometer tests show a good agreement with a chassis dynamometer set-up down to emissions in the range of 1·10 10 #/km. Parallel on-line soot measurements by a photo acoustic soot sensor (PASS) were applied as independent measurement technique and indicate a good on-road performance for the PN-PEMS. PN-to-soot ratios were 1.3·10 12 #/mg, which was comparable for both test cell and on-road measurements. During on-road trips different driving styles as well as different road types were investigated. Comparisons to the world harmonized light-duty test cycle (WLTC) 5.3 and to European field operational test (euroFOT) data indicate the PEMS trips to be representative for normal driving. Driving situations in varying traffic seem to be a major contributor to a high test-to-test variability of PN emissions. However, there is a trend to increasing PN emissions with more severe driving styles. A cold start effect is clearly visible for PN, especially at low ambient temperatures down to 8 °C.