Analysis of emissions from various driving cycles based on real driving measurements obtained in a high-altitude city

Vehicle emissions standards and regulations remain weak in high-altitude regions. In this study, vehicle emissions from both the New European Driving Cycle and the Worldwide harmonized Light-duty driving Test Cycle were analyzed by employing on-road test data collected from typical roads in a high-altitude city. On-road measurements were conducted on five light-duty vehicles using a portable emissions measurement system. The certification cycle parameters were synthesized from real-world driving data using the vehicle specific power methodology. The analysis revealed that under real-world driving conditions, all emissions were generally higher than the estimated values for both the New European Driving Cycle and Worldwide harmonized Light-duty driving Test Cycle. Concerning emissions standards, more CO, NOx, and hydrocarbons were emitted by China 3 vehicles than by China 4 vehicles, whereas the CO2 emissions exhibited interesting trends with vehicle displacement and emissions standards. These results have potential implications for policymakers in regard to vehicle emissions management and control strategies aimed at emissions reduction, fleet inspection, and maintenance programs.

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Development of Operating Mode Distribution Models for Light-Duty Vehicles on Unrestricted Access Roadways

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198120937965 ◽

2020 ◽

Vol 2674 (10) ◽

pp. 416-428

Author(s):

Jia Li ◽

Hanhui He ◽

Bo Peng

Keyword(s):

Real World ◽

Operating Mode ◽

Specific Power ◽

Trajectory Data ◽

Average Speed ◽

The Real ◽

Light Duty ◽

Unrestricted Access ◽

Data Points ◽

Light Duty Vehicles

The key correlating traffic variable for modeling vehicle emissions has evolved from average speed to vehicle-specific power (VSP), and recently to operating mode as defined in Motor Vehicle Emission Simulator (MOVES). The analysis of operating mode and its distribution, however, requires a large amount of data and is time consuming and challenging. This paper attempts to build models between the operating mode distributions and the common traffic variable—average speed—to facilitate the emission estimation. Focusing on light-duty vehicles and unrestricted access roadways, a floating car survey was conducted separately on arterials and collectors in Shaoshan, China. The trajectory data were processed to reveal the characteristics of operating mode distributions. A key finding is that, when the data points of the operating mode of idle are excluded, the VSP distributions of the remaining data points follow logistic distributions and the parameters can be linearly regressed with the average speed. Arterials and collectors feature different operating mode distributions even at the same average speed, and therefore different models were developed. The models were then applied to generate operating mode distributions, which were validated with the real-world data from the test bed and which, when compared with the default values generated by MOVES, fit the real-world condition better.

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The WLTC vs NEDC: A Case Study on the Impacts of Driving Cycle on Engine Performance and Fuel Consumption

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.18.3.2021.19.0696 ◽

2021 ◽

Vol 18 (3) ◽

pp. 9071-9081

Author(s):

Jakub Lasocki

Keyword(s):

Fuel Consumption ◽

Combustion Engine ◽

Engine Performance ◽

Driving Cycle ◽

Performance Characteristics ◽

Pollutant Emission ◽

Strong Impact ◽

Light Duty ◽

Light Duty Vehicles

The World-wide harmonised Light-duty Test Cycle (WLTC) was developed internationally for the determination of pollutant emission and fuel consumption from combustion engines of light-duty vehicles. It replaced the New European Driving Cycle (NEDC) used in the European Union (EU) for type-approval testing purposes. This paper presents an extensive comparison of the WLTC and NEDC. The main specifications of both driving cycles are provided, and their advantages and limitations are analysed. The WLTC, compared to the NEDC, is more dynamic, covers a broader spectrum of engine working states and is more realistic in simulating typical real-world driving conditions. The expected impact of the WLTC on vehicle engine performance characteristics is discussed. It is further illustrated by a case study on two light-duty vehicles tested in the WLTC and NEDC. Findings from the investigation demonstrated that the driving cycle has a strong impact on the performance characteristics of the vehicle combustion engine. For the vehicles tested, the average engine speed, engine torque and fuel flow rate measured over the WLTC are higher than those measured over the NEDC. The opposite trend is observed in terms of fuel economy (expressed in l/100 km); the first vehicle achieved a 9% reduction, while the second – a 3% increase when switching from NEDC to WLTC. Several factors potentially contributing to this discrepancy have been pointed out. The implementation of the WLTC in the EU will force vehicle manufacturers to optimise engine control strategy according to the operating range of the new driving cycle.

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Smart rule-based diesel engine control strategies by means of predictive driving information

International Journal of Engine Research ◽

10.1177/1468087419835696 ◽

2019 ◽

Vol 20 (10) ◽

pp. 1047-1058 ◽

Cited By ~ 5

Author(s):

Giovanni Vagnoni ◽

Markus Eisenbarth ◽

Jakob Andert ◽

Giuseppe Sammito ◽

Joschka Schaub ◽

...

Keyword(s):

Fuel Consumption ◽

Control Strategies ◽

Control Unit ◽

Future Research ◽

Engine Control ◽

Test Cycle ◽

Rule Based ◽

Prediction Horizon ◽

Light Duty ◽

Path Control

The increasing connectivity of future vehicles allows the prediction of the powertrain operational profiles. This technology will improve the transient control of the engine and its exhaust gas aftertreatment systems. This article describes the development of a rule-based algorithm for the air path control, which uses the knowledge of upcoming driving events to reduce especially [Formula: see text] and particulate (soot) emissions. In the first section of this article, the boosting and the lean [Formula: see text] trap systems of a diesel powertrain are investigated as relevant sub-systems for shorter prediction horizons, suitable for Car-to-X communication range. Reference control strategies, based on state-of-the-art engine control unit algorithms and suitable predictive control logics, are compared for the two sub-systems in a model in the loop simulation environment. The simulation driving cycles are based on Worldwide harmonized Light-duty Test Cycle and Real Driving Emissions regulations. Due to the shorter, and consequently more probable, prediction horizon and the demonstrated emission improvements, a dedicated rule-based algorithm for the air path control is developed and benchmarked in the Worldwide harmonized Light-duty Test Cycle as described in the second part of this article. Worldwide harmonized Light-duty Test Cycle test results show an improvement potential for engine-out soot and [Formula: see text] emissions of up to 5.2% and 1.2%, respectively, for the air path case and a reduction of the average fuel consumption in Real Driving Emissions of up to 1% for the lean NOx trap case. In addition, the developed rule-based algorithm allows the adjustment of the desired NOx–soot trade-off, while keeping the fuel consumption constant. The study concludes with brief recommendations for future research directions, as for example, the introduction of a prediction module for the estimation of the vehicle operational profile in the prediction horizon.

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Measurement and Evaluation of Real-World Speed and Acceleration Activity Envelopes for Light-Duty Vehicles

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2503-14 ◽

2015 ◽

Vol 2503 (1) ◽

pp. 128-136 ◽

Cited By ~ 8

Author(s):

Bin Liu ◽

H. Christopher Frey

Keyword(s):

Real World ◽

Test Procedure ◽

Accurate Estimation ◽

Vehicle Type ◽

Light Duty ◽

Road Grade ◽

Light Duty Vehicle ◽

Curb Weight ◽

Vehicle Activity ◽

Light Duty Vehicles

Accurate estimation of vehicle activity is critically important for the accurate estimation of emissions. To provide a benchmark for estimation of vehicle speed trajectories such as those from traffic simulation models, this paper demonstrates a method for quantifying light-duty vehicle activity envelopes based on real-world activity data for 100 light-duty vehicles, including conventional passenger cars, passenger trucks, and hybrid electric vehicles. The vehicle activity envelope was quanti-fied in the 95% frequency range of acceleration for each of 15 speed bins with intervals of 5 mph and a speed bin for greater than 75 mph. Potential factors affecting the activity envelope were evaluated; these factors included vehicle type, transmission type, road grade, engine displacement, engine horsepower, curb weight, and ratio of horsepower to curb weight. The activity envelope was wider for speeds ranging from 5 to 20 mph and narrowed as speed increased. The latter was consistent with a constraint on maximum achievable engine power demand. The envelope was weakly sensitive to factors such as type of vehicle, type of transmission, road grade, and engine horsepower. The effect of road grade on cycle average emissions rates was evaluated for selected real-word cycles. The measured activity envelope was compared with those of dynamometer driving cycles, such as the federal test procedure, highway fuel economy test, SC03, and US06 cycles. The effect of intervehicle variability on the activity envelope was minor; this factor implied that the envelope could be quantified based on a smaller vehicle sample than used for this study.

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