Using a new inversion matrix for a fast-sizing spectrometer and a photo-acoustic instrument to determine suspended particulate mass over a transient cycle for light-duty vehicles (original) (raw)
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Environmental science & technology, 2015
The California Air Resources Board (ARB) adopted the Low Emission Vehicle (LEV) III particulate matter (PM) standards in January 2012, which require, among other limits, vehicles to meet 1 mg/mi over the Federal Test Procedure (FTP). One possible alternative measurement approach evaluated to support the implementation of the LEV III standards is Integrated Particle Size Distribution (IPSD), which reports real-time PM mass using size distribution and effective density. The IPSD method was evaluated using TSI's Engine Exhaust Particle Sizer (EEPS, 5.6-560 nm) and gravimetric filter data from more than 250 tests and 34 vehicles at ARB's Haagen-Smit Laboratory (HSL). IPSD mass was persistently lower than gravimetric mass by 56-75% over the FTP tests and by 81-84% over the Supplemental FTP (US06) tests. Strong covariance between the methods suggests test-to-test variability originates from actual emissions differences rather than measurement accuracy, where IPSD offered no statis...
Aerosol Science and Technology
Fast-sizing spectrometers, such as the TSI Engine Exhaust Particle Sizer (EEPS), have been widely used to measure transient particle size distributions of vehicle exhaust. Recently, size distributions measured during different test cycles have begun to be used for calculating suspended particulate mass; however, several recent evaluations have shown some deficiencies in this approach and discrepancies relative to the gravimetric reference method. The EEPS converts electrical charge carried by particles into size distributions based on mobility classification and a specific calibration, and TSI recently released a matrix optimized for vehicle emissions as described by Wang et al. (Submitteda). This study evaluates the performance of the new matrix (soot matrix) relative to the original matrix (default matrix) and reference size distributions measured by a scanning mobility particle sizer (SMPS). Steady-state particle size distributions were generated from the following five sources to evaluate exhaust particulates with various morphologies estimated by mass-mobility scaling exponent: (1) A diesel generator operating on ultralow sulfur diesel, (2) a diesel generator operating on biodiesel, (3) a gasoline direct-injection vehicle operating at two speeds, (4) a conventional port-fuel injection gasoline vehicle, and (4) a light-duty diesel (LDD) vehicle equipped with a diesel particulate filter. Generally, the new soot matrix achieved much better agreement with the SMPS reference for particles smaller than 30 nm and larger than 100 nm, and also broadened the accumulation mode distribution that was previously too narrow using the default matrix. However, EEPS distributions still did not agree with SMPS reference measurements when challenged by a strong nucleation mode during high-load operation of the LDD vehicle. This work quantifies the range of accuracy that can be expected when measuring particle size distribution, number concentration, and integrated particle mass of vehicle emissions when using the new static calibration derived based on the properties of classical diesel soot.
Determination of Suspended Exhaust PM Mass for Light-Duty Vehicles
SAE Technical Paper Series, 2014
This study provides one of the first evaluations of the integrated particle size distribution (IPSD) method in comparison with the current gravimetric method for measuring particulate matter (PM) emissions from light-duty vehicles. The IPSD method combines particle size distributions with size dependent particle effective density to determine mass concentrations of suspended particles. The method allows for simultaneous determination of particle mass, particle surface area, and particle number concentrations. It will provide a greater understanding of PM mass emissions at low levels, and therefore has the potential to complement the current gravimetric method at low PM emission levels. Six vehicles, including three gasoline direct injected (GDI) vehicles, two port fuel injected (PFI) vehicles, and one diesel vehicle, were tested over the Federal Test Procedure (FTP) driving cycle on a light-duty chassis dynamometer. PM mass emissions were determined by the gravimetric (M Gravimetric) and IPSD (M IPSD) methods. The results show a systematic bias between methods, with the M IPSD underestimating particle mass relative to M Gravimetric (M IPSD = 0.63 × M Gravimetric), although there is a relatively strong correlation (R 2 =0.79) between the methods. The real-time M IPSD showed that more than 55% of the PM mass comes from the first 100 seconds of the FTP for GDI vehicles.
Atmospheric Environment, 2006
Several aerosol instruments are generally used to study the concentration and characteristics of exhaust particle emissions. These are based on different operational principles and usually record a different particle property. As a result, the definition of an absolute emission level is ambiguous and the consistency, i.e. the uniformity and response of the measurements to the input variables, becomes the main quality issue. Here we present four reduced variables, which are derived from the primary information provided by a condensation particle counter, a diffusion charger, an electrical lowpressure impactor and the gravimetric filter-based particulate matter measurement. The variables correspond to a total vs. solid particle number concentration, a mean diameter, an apparent density and a mass-specific surface. The variables were first compared on a relative scale, in order to examine the uniformity of the underlying measurements. Then they were compared on an absolute scale with particle properties found in the literature to confirm the validity of the measurement level of each instrument. Based on the values of the variables, it is verified that different aerosol instruments and methods may produce consistent measurements when attention is given to the sampling protocol and conditions. However, measurement particularities intrinsic to some methods, such as the adsorption of gaseous species on the gravimetric filter and the assumption of unit density for the calculation of the number concentration by the electrical low-pressure impactor, may lead to deviations from this general rule. Overall, our comparisons demonstrated that such reduced variables may serve both as a means to recognise abnormal measurement occasions and to discriminate the effects of fuel, driving condition and vehicle technology on particle emissions.
An Analysis of Methods for Measuring Particulate Matter Mass Emissions
2009
Abstract Studies have shown that there are a significant number of chemical species present in engine exhaust particulate matter emissions. Additionally, the majority of current world-wide regulatory methods for measuring engine particulate emissions are gravimetrically based. As modern engines considerably reduce particulate mass emissions, these methods become less stable and begin to display higher levels of measurement uncertainty.
Asian Journal of Atmospheric Environment, 2016
Particulate matter (PM) in the atmosphere has wideranging health, environmental, and climate effects, many of which are attributed to fine-mode secondary organic aerosols. PM concentrations are significantly enhanced by primary particle emissions from traffic sources. Recently, in order to reduce CO 2 and increase fuel economy, gasoline direct injected (GDI) engine technology is increasingly used in vehicle manufactures. The popularization of GDI technique has resulted in increasing of concerns on environmental protection. In order to better understand variations in chemical composition of particulate matter from emissions of GDI vehicle versus a port fuel injected (PFI) vehicle, a high time resolution chemical composition of PM emissions from GDI and PFI vehicles was measured at facility of Transport Pollution Research Center (TPRC), National Institute of Environmental Research (NIER), Korea. Continuous measurements of inorganic and organic species in PM were conducted using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The HR-ToF-AMS provides insight into nonrefractory PM composition, including concentrations of nitrate, sulfate, hydrocarbon-like and oxygenated organic aerosol, and organic mass with 20 sec time resolution. Many cases of PM emissions during the study were dominated by organic and nitrate aerosol. An overview of observed PM characteristics will be provided along with an analysis of comparison of GDI vehicle versus PFI vehicle in PM emission rates and oxidation states.
Atmospheric Environment, 2009
Please cite this article as: Wehner, B., Uhrner, U., von Löwis, S., Zallinger, M., Wiedensohler, A. Aerosol number size distributions within the exhaust plume of a diesel and a gasoline passenger car under on-road conditions and determination of emission factors, Atmospheric Environment (2008), Abstract 13 14 A new setup has been developed and built to measure number size distributions of exhaust 15 particles and thermodynamic parameters under real traffic conditions. Measurements have 16 been performed using a diesel and a gasoline passenger car driving with different speeds and 17 engine conditions. Significant number of nucleation mode particles was found only during 18 high load conditions, i.e. high car and engine speed behind the diesel car. The number 19 concentration of soot mode particles varied within a factor of two for different engine 20 conditions while the concentration of nucleation mode particles varied up to two orders of 21 magnitude. The results show that roadside measurements are still quite different from those 22 behind the tailpipe. Beside dilution also transformation processes within the first meter behind 23 the tailpipe play an important role, such as nucleation and growth. Emission factors were 24 calculated and compared with those obtained by other studies. Emission factors for particles 25 larger than 25 nm (primary emissions) varied within 1.1·10 14 km -1 and 2.7 ·10 14 km -1 for the 26 diesel car and between 0.6·10 12 km -1 and 3.5 ·10 12 km -1 for the gasoline car. The advantage of 27 these measurements is the exhaust dilution under atmospheric conditions and the size-28 resolved measurement technique to divide into primary emitted and secondary produced 29 particles. 30 31 ARTICLE IN PRESS
Particulate matter mass measurements for low emitting diesel powered vehicles: what’s next?
Legislation word-wide imposes stringent emission standards for particulate matter emitted by diesel engines, as an outcome of evidence associating emitted particulate with a series of adverse health effects. Such emission standards call for significant reductions in the particulate matter emission levels for small and large on-road diesel vehicles. In fact, emission levels adopted for the near future are so low that the existing, regulated procedures might not be sensitive enough to accurately determine the absolute level of emissions. In this regard, extensive research is conducted in the direction of both improving existing procedures and developing alternative methods for more sensitive particulate matter measurements. This review paper summarizes the developments in the area and provides an outlook to the future. At first, the character of diesel particulate matter (DPM) is shortly discussed, mainly to show that the complex nature of emitted particulate is responsible for a series of implications when its quantitative determination is considered. Secondly, the regulated procedure for sampling and measurement of DPM is reviewed and its main qualities and shortcomings are presented. The recent technical advances aimed at improving the characteristics of the reference procedure in the measurement of ultra-low emission levels are then presented. Next the presentation of alternative methods follows which are gradually incorporated in regulations for particulate matter sampling. The strength of these techniques is that only a small fraction of exhaust is sampled and conditioned before measurement, hence significantly reducing the cost compared to the reference procedure. In addition to sampling, the determination of the actual particulate mass emitted is an area which has attracted significant developments. The most relevant instrumentation for DPM determination is also described and their potential for application in emissions certification is examined based on published evidence. Finally, the cost of the different sampling and instrumentation techniques is compared to demonstrate the cost-effectiveness of each option.
Journal of Liquid Chromatography & Related Technologies, 2007
Soot particles emitted from a light duty (LD) Volkswagen diesel engine running at different operating points (speed and torque levels) are analyzed for mean size determination using a laser-based three Wavelength Extinction Method (3-WEM). For this reason, collected soot samples are suspended using an appropriate sample preparation technique with optimized conditions of sonication as it revealed its effect on the soot mean particle size measured by 3-WEM. An online Scanning Mobility Particle Analyzer (SMPS) is also used to measure soot emission at identical engine operating points. Size values obtained from SMPS are lower than those of suspended soot samples obtained from 3-WEM. The size discrepancies are mainly related to the required sample preparation procedure employed for 3-WEM measurements. The engine operating points affect, differently, the size measurements obtained from SMPS and 3-WEM. Sedimentation Field-Flow Fractionation (SdFFF) is used for density determination of soot samples based on size measurements of fractions collected at peak maxima