scholarly journals Characterization of Exhaust CO, HC and NOx Emissions from Light-Duty Vehicles under Real Driving Conditions

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1125
Author(s):  
Hui Mei ◽  
Lulu Wang ◽  
Menglei Wang ◽  
Rencheng Zhu ◽  
Yunjing Wang ◽  
...  
Keyword(s):  
Specific Power ◽  
Emission Measurement ◽  
Nox Emissions ◽  
Emission Rates ◽  
Gaseous Emissions ◽  
Passenger Cars ◽  
Light Duty ◽  
Driving Conditions ◽  
Hc Emissions ◽  
Light Duty Vehicles

On-road exhaust emissions from light-duty vehicles are greatly influenced by driving conditions. In this study, two light-duty passenger cars (LDPCs) and three light-duty diesel trucks (LDDTs) were tested to investigate the on-road emission factors (EFs) with a portable emission measurement system. Emission characteristics of carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx) emitted from vehicles at different speeds, accelerations and vehicle specific power (VSP) were analyzed. The results demonstrated that road conditions have significant impacts on regulated gaseous emissions. CO, NOx, and HC emissions from light-duty vehicles on urban roads increased by 1.1–1.5, 1.2–1.4, and 1.9–2.6 times compared with those on suburban and highway roads, respectively. There was a rough positive relationship between transient CO, NOx, and HC emission rates and vehicle speeds, while the EFs decreased significantly with the speed decrease when speed ≤ 20 km/h. The emissions rates of NOx and HC tended to increase and then decrease as the acceleration increased and the peak occurred at 0 m/s2 without considering idling conditions. For HC and CO, the emission rates were low and changed gently with VSP when VSP < 0, while emission rates increased gradually with the VSP increase when VSP > 0. For NOx NOx emission rates were lower and had no obvious change when VSP < 0. However, NOx emissions were positively correlated with VSP, when VSP > 0.

Evaluation of the Precision and Accuracy of Cycle-Average Light Duty Gasoline Vehicles Tailpipe Emission Rates Predicted by Modal Models

2020 ◽  
Vol 2674 (7) ◽  
pp. 566-584
Author(s):  
Tongchuan Wei ◽  
H. Christopher Frey
Keyword(s):  
Goodness Of Fit ◽  
Motor Vehicle ◽  
Vehicle Group ◽  
Specific Power ◽  
Emission Measurement ◽  
Emission Rates ◽  
Light Duty ◽  
Wide Range ◽  
Gasoline Vehicles ◽  
Precision And Accuracy

A vehicle specific power (VSP) modal model and the MOtor Vehicle Emission Simulator (MOVES) Operating Mode (OpMode) model have been used to evaluate and quantify the fuel use and emission rates (FUERs) for on-road vehicles. These models bin second-by-second FUERs based on factors such as VSP, speed, and others. The validity of binning approaches depends on their precision and accuracy in predicting variability in cycle-average emission rates (CAERs). The objective is to quantify the precision and accuracy of the two modeling methods. Since 2008, North Carolina State University has used portable emission measurement systems to measure tailpipe emission rates for 214 light duty gasoline vehicles on 1,677 driving cycles, including 839 outbound cycles and 838 inbound cycles on the same routes. These vehicles represent a wide range of characteristics and emission standards. For each vehicle, the models were calibrated based on outbound cycles and were validated based on inbound cycles. The goodness-of-fit of the calibrated models was assessed using linear least squares regression without intercept between model-predicted versus empirical CAERs for individual vehicles. Based on model calibration and validation, the coefficients of determination ( R2) typically range from 0.60 to 0.97 depending on the vehicle group and pollutant, indicating moderate to high precision, with precision typically higher for higher-emitting vehicle groups. The slopes of parity plots for each vehicle group and all vehicles typically range from 0.90 to 1.10, indicating good accuracy. The two modeling approaches are similar to each other at the microscopic and macroscopic levels.

Recent evidence concerning higher NOx emissions from passenger cars and light duty vehicles

2011 ◽  
Vol 45 (39) ◽  
pp. 7053-7063 ◽  
Author(s):  
David C. Carslaw ◽  
Sean D. Beevers ◽  
James E. Tate ◽  
Emily J. Westmoreland ◽  
Martin L. Williams
Keyword(s):  
Nox Emissions ◽  
Passenger Cars ◽  
Light Duty ◽  
Light Duty Vehicles

Emissions From Light-Duty Passenger Cars Fueled With Ternary Blend of Gasoline, Methanol, and Ethanol

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Chuanzhen Zhang ◽  
Yunshan Ge ◽  
Jianwei Tan ◽  
Lan li ◽  
Zihang Peng ◽  
...  
Keyword(s):  
Volatile Compounds ◽  
Ternary Blend ◽  
Nox Emissions ◽  
Passenger Cars ◽  
Evaporative Emissions ◽  
Light Duty ◽  
Hc Emissions

In this study, the emissions from three passenger cars with gasoline, methanol, ethanol, and their blend were tested. The results show that the CO and HC emissions from the exhaust of the vehicles fueled with E7.5/M7.5 decrease compared with those from the vehicles fueled with the gasoline, E10 or M15, while NOx emissions increase by 7.5–25.8%. Formaldehyde and acetaldehyde are found higher for the vehicles fueled with E7.5/M7.5, whereas a series of volatile compounds become lower. Evaporative emissions of the vehicles fueled with E7.5/M7.5 were higher than those of the vehicles fueled with gasoline, by a range of 16.39–28.28%.

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

2020 ◽  
Vol 234 (6) ◽  
pp. 1563-1571 ◽  
Author(s):  
Meng Lyu ◽  
Xiaofeng Bao ◽  
Yunjing Wang ◽  
Ronald Matthews
Keyword(s):  
High Altitude ◽  
Real World ◽  
Vehicle Emissions ◽  
Control Strategies ◽  
Driving Cycle ◽  
Specific Power ◽  
Test Cycle ◽  
Light Duty ◽  
And Control ◽  
Light Duty Vehicles

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.

Digital Signal Processing Approach to Identify the Boundary of Vehicle Idle Status during Operation

2018 ◽  
Vol 2672 (25) ◽  
pp. 35-45
Author(s):  
Qing Li ◽  
Fengxiang Qiao ◽  
Lei Yu ◽  
Shuyan Chen ◽  
Tiezhu Li
Keyword(s):  
Fuel Consumption ◽  
Digital Signal ◽  
Operating Mode ◽  
Frequency Component ◽  
High Frequency Component ◽  
Specific Power ◽  
Emission Measurement ◽  
Emission Rates ◽  
Wide Range ◽  
Light Duty Vehicle

The MOVES is a tool to estimate on- and off-road emissions, in which 23 operating mode identification bins were defined based on vehicles’ specific power, speed, and acceleration. Bin 1 indicates an idling mode with the speed within 1.0 mph. However, the speed boundary in an earlier model of MOBILE 6.2 was 2.5 mph. Neither the change in the idling definition of the two models nor the speed boundary were investigated and discussed. This study proposed a method to theoretically redefine the idle boundary by characterizing vehicle emission rates. Vehicle speeds close to 0 mph were carefully studied based on 10,000-mile on-board emission tests in the state of Texas. A portable emission measurement system was used to detect real-time emissions from a 12-year-old gasoline light-duty vehicle, while the vehicle’s activity information was collected from an On-Board Diagnostic (OBD) II port. Power spectral density analysis was conducted on the collected emission and fuel consumption rates to identify a cut-off point that separates the frequency period with higher and lower energy. A Chebeshev I filter was designed to remove the high-frequency component to visualize the variables of emissions and fuel consumption on the vehicle’s moving trend lines. Based on observation and analysis results, 2.26 mph was identified as a boundary for an idle mode at an acceptance level of 95% significant change. It is recommended that the proposed method be applied to the emissions of more different types of vehicles with a wide range of mileages to validate the newly defined idle boundary.

scholarly journals Evaluating the Effects of One-Way Traffic Management on Different Vehicle Exhaust Emissions Using an Integrated Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jieyu Fan ◽  
Kun Gao ◽  
Yingying Xing ◽  
Jian Lu
Keyword(s):  
Traffic Management ◽  
Integrated Approach ◽  
Exhaust Emissions ◽  
Traffic Emissions ◽  
Specific Power ◽  
Emission Measurement ◽  
Emission Rates ◽  
Vehicle Exhaust ◽  
Emission Data ◽  
The Road

One-way traffic management is a recognized traffic organization to improve traffic efficiency and safety, but its effects on different traffic emissions remains unclear. This paper aims to investigate the impacts of one-way traffic management on three typical vehicle exhaust emissions including Carbonic Oxide (CO), Hydrocarbon Compounds (HC), and Nitrogen Oxides (NOx) in a traffic system using an integrated approach. Field experiment was conducted to collect the vehicular emission data under different traffic conditions using the onboard portable emission measurement system. An instantaneous emission model (i.e., Vehicle Specific Power) is calibrated using the collected field emission data and is incorporated into the microscopic traffic simulation tool VISSIM for quantifying the emissions before and after one-way traffic management through simulation. Two scenarios based on real networks and traffic demands of peak hours in part areas of Shanghai are developed for simulation and evaluation. The results show that in the intersections, the emission rates of COHC, NOx after one-way traffic management is significantly reduced by 20.46%, 21.29% and 21.06%, respectively. In the road sections, the emission rates of CO, HC, NOx in the road sections decrease by 23.38% and 26.29%. The overall CO, HC, NOx emissions in the studied network reduce by 21.34%, 22.29% and 23.77% separately due to one-way traffic management. The results provide insights into the derivative effects of one-way traffic management on traffic emissions in the intersections, road sections and network levels, and thus support scientific traffic management for promoting the sustainability of transport system.

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