On-board Emissions Measurement System Research Articles

Design and evaluation of a calibration system for portable motor vehicle emission particle number detectors

The supervision of the number concentration of particles emitted from motor vehicles is becoming increasingly strict. The regular calibration of portable particle number (PN) detectors is a prerequisite to ensure the effective supervision of PN. At present, the calibration of PN detectors is mostly completed in the laboratory. However, due to the complexity and poor portability of the laboratory calibration system, it is difficult to use this system for the on-site calibration of PN detectors. To this end, a portable motor vehicle emission PN detector calibration system based on the principles of negative pressure siphon atomization, differential electrical mobility classifier, and fA-level weak current measurement was developed, which could quickly and accurately calibrate the PN detector on-site. The system consists of three parts: an atomizer generator, a plate differential mobility analyzer (PDMA), and an aerosol electrometer. The atomizer generator produces NaCl particles with a median particle size of 70 nm and fluctuation of <10%. The particle size classification deviation of the PDMA is <3.7% and the counting error of the aerosol electrometer is <10%. The On-board Emissions Measurement System was calibrated as a PN detector on a self-developed portable calibration system as well as on a laboratory calibration system. The comparison results showed that the measurement results of the portable calibration system were closer to the instrument factory report certificate results, and the maximum error did not exceed 6.72%.

Characterizing Real-World Particle-Bound Polycyclic Aromatic Hydrocarbon Emissions from Diesel-Fueled Construction Machines

This study employed an onboard emission measurement system to measure the real-world emission factors of particulate matter (PM), particle-bound polycyclic aromatic hydrocarbons (PAHs), and gaseous air pollutants for different types of diesel-fueled non-road construction machines operated inside confined spaces within a brick manufacturing factory located in Taiwan. To the best knowledge of the authors, this is the first study that reports real-world PM, PAH, and gaseous pollutant emission factors for non-road engines in Taiwan. The mean real-world fuel-specific emission factors of PM, carbon monoxide, total hydrocarbons, and nitric oxide were 0.712–1.17, 8.27–17.9, 3.04–5.77, and 38.1–96.8 g/kg-fuel, respectively, for the test machines. Likewise, mean ΣPAHs emission factors ranged from 157 to 230 μg/kg-fuel for three types of test machines. Further, the average emission of particle-bound PAH per unit PM emission ranged from 213 to 384 μg-PAH/g-PM. Among the analyzed PAHs, the medium-molecular weight (3- and 4-ring) compounds contributed to the largest share of particle-bound PAH emissions. However, in terms of Benzo[a]pyrene equivalent (BaPeq) toxicity, the high-molecular weight (5- and 6-ring) PAHs were more important, as they had the highest BaPeq toxic emission factors. This study provides detailed composition and emission factors of particle-bound PAHs in non-road diesel construction machine emissions, which may be useful as a chemical fingerprint for source apportionment studies.

自動車の排出ガス・粉じんと大気環境―第5講 車載型排出ガス計測システムを用いたリアルワールドでの排出ガス計測―

自動車の排出ガス・粉じんと大気環境―第5講 車載型排出ガス計測システムを用いたリアルワールドでの排出ガス計測―

PM2.5 emissions from light-duty gasoline vehicles in Beijing, China

As stricter standards for diesel vehicles are implemented in China, and the use of diesel trucks is forbidden in urban areas, determining the contribution of light-duty gasoline vehicles (LDGVs) to on-road PM2.5 emissions in cities is important. Additionally, in terms of particle number and size, particulates emitted from LDGVs have a greater health impact than particulates emitted from diesel vehicles. In this work, we measured PM2.5 emissions from 20 LDGVs in Beijing, using an improved combined on-board emission measurement system. We compared these measurements with those reported in previous studies, and estimated the contribution of LDGVs to on-road PM2.5 emissions in Beijing. The results show that the PM2.5 emission factors for LDGVs, complying with European Emission Standards Euro-0 through Euro-4 were: 117.4±142, 24.1±20.4, 4.85±7.86, 0.99±1.32, 0.17±0.15mg/km, respectively. Our results show a significant decline in emissions with improving vehicle technology. However, this trend is not reflected in recent emission inventory studies. The daytime contributions of LDGVs to PM2.5 emissions on highways, arterials, residential roads, and within urban areas of Beijing were 44%, 62%, 57%, and 57%, respectively. The contribution of LDGVs to PM2.5 emissions varied both for different road types and for different times.

STUDY OF EFFECT OF SPEED, ACCELERATION AND DECELERATION OF SMALL PETROL CAR ON ITS TAIL PIPE EMISSION

Pollution from vehicles is due to discharges like Carbon monoxide (CO), Carbon dioxide (CO 2 ), Hydrocarbon (HC) and Oxides of Nitrogen (NOx) through their tailpipe. Cars, being in dominant proportions (36.5%) in Indian traffic stream with small cars above 50% in total car proportions, are the main contributors to pollutants. Literature reveals that all factors being constant, at signalized intersection, car emission rates are the function of speed and acceleration. Since it is difficult to collect speed and position data at the actual intersection, this study is conducted on link road between National Highway 31 and IIT Guwahati, India, replicating the queue leader at signalized intersection. Tailpipe emissions are measured using onboard emission measurement system and speed and position data are measured using GPS device. Study illustrates that tailpipe emissions like CO, HC and NOx are sensitive to vehicle speed at similar acceleration level. Tailpipe emission rate initially decreases with increase in speed and then increase afterwards with further increase in speed, at similar acceleration level. Emission rates are found to increase with increase in vehicle acceleration rate. It was observed that deceleration does not influence tailpipe emission of small cars.

Statistical Model for Estimating Carbon Dioxide Emissions from a Light-Duty Gasoline Vehicle

The objective of this research was development of a statistical model for estimating vehicle tailpipe emissions of carbon dioxide (CO2). Forty hours of second-by-second emissions data (144,000 data points) were collected using an On-Board emissions measurement System (Horiba OBS-1300) installed in a 2007 Dodge Charger car. Data were collected for two roadway types, arterial and highway, around Arlington, Texas, and two different time periods, off peak and peak (both a.m. and p.m.). Multiple linear regression and SAS software were used to build emission models from the data, using predictor variables of velocity, acceleration and an interaction term. The arterial model explained 61% of the variability in the emissions; the highway model explained 27%. The arterial model in particular represents a reasonably good compromise between accuracy and ease of use. The arterial model could be coupled with velocity and acceleration profiles obtained from a micro-scale traffic simulation model, such as CORSIM, or from field data from an instrumented vehicle, to estimate percent emission reductions associated with local changes in traffic system operation or management.

Determination of Safe Roadway Buffer Width to Protect Human Health from NO2 Exposure: A Case Study for Grand Prairie, TX

According to the U.S. Environmental Protection Agency (EPA), in 2010 mobile sources in the U.S. contributed 58% of carbon monoxide (CO), 56% of nitrogen oxide (NOx), and 33% of Volatile Organic Compounds (VOCs). Onroad sources also emit a variety of air toxics, including benzene, toluene, and xylenes. The case study presented here determines a safe roadway buffer width to protect human health from nitrogen dioxide (NO2) exposure along an arterial in Grand Prairie, Texas. NO2 health effects include eye, nose, throat, and lung irritation; cough; shortness of breath; tiredness and nausea. In the Dallas Fort Worth region, where Grand Prairie is located, on-road vehicles contribute about half of NOx emissions. Vehicle NOx emission rates along Great Southwest Parkway were measured using a Horiba 1300 OBS onboard emission measurement system, to determine a maximum g/mile emission factor for the corridor. Hourly DFW meteorological data for a 5-year period was processed using CAL3QHCR to determine the 10 worst-case hourly meteorological combinations. The maximum emission factor and worst-case meteorological conditions were input into the line source dispersion model CALRoads View to determine worst-case NO2 concentrations at 5- m intervals away from the roadway. CALRoads View output was post-processed in Arc View GIS to plot concentrations at receptor locations. Worst-case concentrations were compared to the 1-hour NO2 National Ambient Air Quality Standard (100 ppb). For the current Great Southwest traffic volume, it was found that the standard would not be exceeded. Additional CALRoads View runs were conducted to determine how much the traffic volume could increase, and still avoid exceedances outside a 20-foot buffer width, which is a common setback distance in residential areas. It was determined that the traffic volume could increase by a factor of 10 and still protect human health from NO2 impacts, using a 20-foot buffer.

Measurements of In-Use Emissions from Modern Vehicles Using an On-Board Measurement System

Emissions from "low emitting" modern vehicles were measured on-road using a Fourier transform infrared (FTIR) on-board emissions measurement system. Twenty vehicles were tested on road and on a chassis dynamometer. A subset of four vehicles was tested on a test track as well as on the dynamometer. Comparison of on-board measurements with laboratory measurements while operating on the dynamometer showed agreement within measurement and test to test variability. Comparison of dynamometer measurements with test track measurements showed some larger differences attributable to track test conditions. On-road and dynamometer tests were conducted on the remaining 16 vehicles, with the on-road testing including freeway, arterial, and residential streets. The on-road testing showed that most of the low emitting vehicles under most operating conditions are operating below certification levels. Most vehicles reached a hot stabilized condition within 60 to 100 s. Hot running emissions were on average very low once the catalyst lights off. For NMHC, the majority of the "certification" emissions occur during the start-up, especially for PZEVs. NOx and CO also showed a high fraction of "certification" emissions during start-up, but also showed emission spikes under hot running conditions, especially during transients.

Analyses of Mechanism on Roadside Pollution by On-Board Emissions Measurement System (Transient Characteristics of NOx emissions in Vehicles with EGR System in Real Traffic Conditions)

In order to clarify the reason why the NOx emissions factor becomes higher with vehicle acceleration at intersections etc., two freight vehicles of different emission model years, equipped with EGR systems for reduction of NOx, were tested by an on-board NOx measurement system. Higher NOx emissions factors were observed at vehicle starts in lower-gear operations for each vehicle though the total NOx mass emissions of the later model vehicle were less. Larger NOx mass emissions were clearly observed in the engine operation area of lower engine speed and load in real traffic conditions though the NOx mass emissions in steady state conditions was less. NOx emissions characteristics were analyzed in view of engine torque, NOx mass emissions, and the EGR rate, and considering the rate of engine speed change. It was found that lower-gear operations made the rate of engine speed change higher and also the EGR rate lower resulting in higher NOx emissions. This seems to be one of the factors to engender the intensive NOx pollution at roadsides.

Analyses of Mechanism on Roadside Pollution by On-Board Emissions Measurement System

An on-board measurement system that can simultaneously obtain such information as road infrastructure, traffic conditions, driver's operations, vehicle running conditions, and exhaust mass emissions was installed in a light duty freight vehicle with an EGR system and in a minivan without an EGR system. In order to analyze the mechanism of roadside pollution caused by vehicles, road tests were carried out in real traffic conditions. The light duty freight vehicle showed intensive NOx pollution at the roadside in a vehicle start, in which the EGR rate was low, but it was effective to reduce NOx mass emissions at low speed running in traffic jams where the EGR rate was rather high. In the case of the minivan, intensive NOx pollution was observed in low speed running such as in traffic jams. The reduction of NOx during vehicle starts is important for vehicles with an EGR system to reduce intensive NOx pollution at roadsides.

Development of a vehicle emissions monitoring system

Investigation of vehicle emissions with an on-board emissions measurement system can provide a better understanding of how these emissions contribute to air pollution. This paper discusses the design and development by Imperial College London and industrial collaborators of a vehicle performance and emissions monitoring system, including its installation both on test vehicles allowing an interface with the engine management system and those that do not. Results from preliminary field trials and chassis dynamometer testing of the diesel test vehicle are presented. Good correlation between the monitoring system and reference measurements is observed, with differences in aggregate measurements of between 8% and 18% over a standard test cycle. The remote download and synthesis of navigation, performance and emissions data from an in-use vehicle was successfully achieved. This project has shown that it is possible to produce a system suitable for deployment for simultaneous studies over a wide area. However, the non-standard nature of engine management system interfaces for much of the European vehicle fleet presents a significant barrier to implementation. It is therefore recommended that European legislation be enforced to ensure standard interfaces on all new vehicles.

Analyses of Mechanism on Roadside Pollution by On-Board Emissions Measurement System (Characteristics of NOx Emissions in Vehicles with and without EGR System in Real Traffic Conditions)

On-board measurement system that can simultaneously obtain such information as road infrastructure, traffic conditions, driver's operations, vehicle running conditions and exhaust mass emissions, was installed in a light duty freight with EGR system and in one box vehicle without EGR system. In order to analyze mechanism of roadside pollution caused by vehicles, road tests were carried out in real traffic conditions. The vehicle with EGR system showed intensive NOx pollution to roadside in vehicle start, in which EGR rate was low, but it was effective to reduce NOx mass emissions at low speed running in traffic jams where EGR rate was rather high. In case of the vehicle without EGR system, intensive NOx pollution was observed in low speed running such as in traffic jams. The reduction of NOx during vehicle start is important for vehicles with EGR system to reduce intensive NOx pollution at roadside. EGR system is effective to reduce intensive NOx pollution for vehicles without EGR system during low speed running like in traffic jams.

Analyses of Mechanism on Roadside Pollution by On-board Emissions Measurement System(Transient Characteristics of NOx Emissions in Vehicles with EGR System in Real Traffic Conditions)

In order to clarify the reason why the NOx emissions factor is higher at vehicle acceleration at intersections etc, two freight vehicles with EGR system for the reduction of NOx were tested by on-board NOx measurement system. Higher NOx emissions factor was observed at lower gear operations in each vehicle. The NOx emissions characteristics were analyzed in the view of engine torque, NOx mass emissions and EGR ratio, considering the rate of engine speed change. As the results, it was found that lower gear operations made the rate of engine speed change higher and also made EGR ratio lower, resulting in higher NOx emissions. This seems to be one of the factors to engender the intensive NOx pollution at roadside.

Development of hydrocarbon analyzer using heated-NDIR method and its application to on-board mass emission measurement system

A heated NDIR analyzer (H-NDIR) that is capable of measuring CO, CO 2 and HC has been developed, and an on-board emission measurement system using the H-NDIR in combination with a Pitot tube flow meter has been evaluated. It has been confirmed that the results of the mass emission from on-board system shows a satisfactory agreement with those of the CVS-bag measurements in laboratory test. A conversion factor applied in the present study that converts the value of NDIR measurement to correlate with the FID method is 1.66. Using the conversion factor, consistent correlation has been observed for vehicles with different fuel and combustion types.

95/05258 Characterisation and signal reconstruction of an NDIR automotive emissions analyser used for dynamic measurement

A heated NDIR analyzer (H-NDIR) that is capable of measuring CO, CO2 and HC has been developed, and an on-board emission measurement system using the H-NDIR in combination with a Pitot tube flow meter has been evaluated. It has been confirmed that the results of the mass emission from on-board system shows a satisfactory agreement with those of the CVS-bag measurements in laboratory test.A conversion factor applied in the present study that converts the value of NDIR measurement to correlate with the FID method is 1.66. Using the conversion factor, consistent correlation has been observed for vehicles with different fuel and combustion types.