Assessment of the Fuel Composition Impact on Black Carbon Mass, Particle Number Size Distributions, Solid Particle Number, Organic Materials, and Regulated Gaseous Emissions from a Light-Duty Gasoline Direct Injection Truck and Passenger Car (original) (raw)
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Measuring Automotive Exhaust Particles Down to 10 nm
SAE International Journal of Advances and Current Practices in Mobility, 2020
The latest generation of internal combustion engines may emit significant levels of sub-23 nm particles. The main objective of the Horizon 2020 "DownToTen" project was to develop a robust methodology and provide policy recommendations towards the particle number (PN) emissions measurements in the sub-23 nm region. In order to achieve this target, a new portable exhaust particle sampling system (PEPS) was developed, being capable of measuring exhaust particles down to at least 10 nm under real-world conditions. The main design target was to build a system that is compatible with current PMP requirements and is characterized by minimized losses in the sub-23 nm region, high robustness against artefacts and high flexibility in terms of different PN modes investigation, i.e. nonvolatile, volatile and secondary particles. This measurement setup was used for the evaluation of particle emissions from the latest technology engine and powertrain technologies (including vehicles from other Horizon 2020 projects), different fuel types, and a wide range of exhaust aftertreatment systems. Results revealed that in most cases (non-volatile), PN emissions down to 10 nm (SPN10) do not exceed the current SPN23 limit of 6×10 11 p/km. However, there are some cases where SPN10 emissions exceeded the limit, although SPN23 were below that. An interesting finding was that even in the latter cases, the installation of a particle filter could significantly reduce PN emissions across a wide particle size range, fuels, and combustion technology. DownToTen results are being used to scientifically underpin the Euro 7/VII emission standard development in the EU. The method developed and the results obtained may be used to bring in the market clean and efficient vehicle technologies, improve engine and emission control performance with different fuels, and characterize size-fractionated particle chemistry to identify the formation mechanisms and control those in a targeted, costeffective fashion.
Atmosphere
Many countries worldwide have introduced a limit for solid particles larger than 23 nm for the type approval of vehicles before their circulation in the market. However, for some vehicles, in particular for port fuel injection engines (gasoline and gas engines) a high fraction of particles resides below 23 nm. For this reason, a methodology for counting solid particles larger than 10 nm was developed in the Particle Measurement Programme (PMP) group of the United Nations Economic Commission for Europe (UNECE). There are no studies assessing the reproducibility of the new methodology across different laboratories. In this study we compared the reproducibility of the new 10 nm methodology to the current 23 nm methodology. A light-duty gasoline direct injection vehicle and two reference solid particle number measurement systems were circulated in seven European and two Asian laboratories which were also measuring with their own systems fulfilling the current 23 nm methodology. The hot ...
Journal of Aerosol Science, 2016
Particle size distributions measured by the Engine Exhaust Particle Sizer Spectrometer (EEPS) have been reported to disagree with those by scanning mobility particle sizers (SMPS). The discrepancies are larger for the accumulation mode engine exhaust particles than for compact-shape particles. Engine exhaust particles, specifically carbonaceous aggregates, have different charging characteristics compared to nearly spherical particles because aggregates acquire more charges at a given mobility diameter in a unipolar charging environment. Therefore, different instrument matrices, that represent the relationship between particle size and EEPS electrometer current distributions, are needed for compact-shape particles and aggregates. This paper reports on a study to improve the EEPS performance for engine exhaust measurements. The EEPS was calibrated with monodisperse particles from the exhaust of a diesel engine. The geometric mean diameters measured by the EEPS using the original instrument matrix agreed with SMPS within 15% for particles o 50 nm (that were mostly spherical), but underestimated by 20-50% for larger particles (that were mostly aggregates). A new EEPS instrument matrix was developed for fresh engine exhaust, and its performance was evaluated using a diesel engine, two passenger cars with gasoline direct injection (GDI) engines, one vehicle with a turbo direct injection (TDI) diesel engine, and a diesel generator. The geometric mean diameters by the EEPS new matrix agreed with SMPS within 14% for monodisperse engine exhaust particleso 50 nm while larger particles agreed within À 19% to 1%. The new matrix also improved the agreement between EEPS and SMPS for polydisperse exhaust particles from different engines under different operating conditions. Diesel engine tests showed that the total concentration, geometric mean diameter, and geometric standard deviation by the SMPS and EEPS with the new matrix differed less than 16%, 33%, and 9%, respectively, with the greatest differences found for particles o 15 nm.
2011
We report the first in situ size-resolved density measurements of particles produced by premixed charge compression ignition (PCCI) combustion and compare these with conventional diesel exhaust particles. The effective densities (F eff) of sizeclassified particles were determined by measurements with a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM). Particle inherent densities (F i) were calculated using an expression for particle mass given by idealized aggregate (IA) theory, transmission electron microscopy (TEM) measurements of primary particle diameter (d pp), and a comparison of the measured number of particles in each size class with that predicted by a proposed DMA-APM response function for aggregates. The F eff of PCCI and conventional diesel particles were similar over a range of diameters characteristic of their number-size distributions. The F eff were 0.89, 0.58, and 0.51 g/cm 3 for conventional diesel and 0.90, 0.62, and 0.42 g/cm 3 for PCCI particles with 50, 100, and 150 nm electrical mobility diameters (d m), respectively. The error associated with F eff was about one percent of each measurement. The lowest F eff were observed for exhaust gas recirculation (EGR) levels somewhat lower than that required for PCCI operation. The F i of 50 and 100 nm conventional diesel particles were 1.22 (0.14 and 1.77 (0.29 g/cm 3 , which is in good agreement with previously reported values. PCCI F i for these size classes did not differ significantly (1.27 (0.16 and 2.10 (0.20 g/cm 3), suggesting like amounts of adsorbed liquid hydrocarbons. In addition, for 150 nm particles, the PCCI and conventional F i were the same (2.20 (0.34 g/cm 3). Given the close density values, we expect that particulate emissions control with diesel particulate filters (DPFs) would not be adversely affected by PCCI particle physical properties.
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.
Sampling of Non-Volatile Vehicle Exhaust Particles: A Simplified Guide
SAE International Journal of Engines, 2012
Recently, a particle number (PN) limit was introduced in the European light-duty vehicles legislation. The legislation requires measurement of PN, and particulate mass (PM), from the full dilution tunnel with constant volume sampling (CVS). Furthermore, PN measurements will be introduced in the next stage of the European Heavy-Duty regulation. Heavy-duty engine certification can be done either from the CVS or from a partial flow dilution system (PFDS). For research and development purposes, though, measurements are often conducted from the raw exhaust, thereby avoiding the high installation costs of CVS and PFDS. Although for legislative measurements requirements exist regarding sampling and transport of the aerosol sample, such requirements do not necessarily apply for raw exhaust measurements. Thus, measurement differences are often observed depending on where in the experimental set up sampling occurs. The objective of this paper is to summarize and discuss particle loss mechanisms. Simple equations are given for the most important mechanisms. Topics like isokinetic sampling and agglomeration are discussed for various typical cases. Special emphasis is placed on thermophoretic losses since thermophoresis is the most important particle removal mechanism for raw exhaust sampling from modern engines. Sampling from high pressure exhaust gas is also mentioned, and comparisons of the effect of tubing materials on particle removal are carried out. Finally, expected losses for typical cases are shown.
SAE Technical Paper Series
The research on health effects of soot particles has demonstrated their toxic impact on humans, especially for the smallest ones that can pass through the lungs into the bloodstream and be transferred to other parts of the body. Since the Euro 5b regulation, the total particle number (PN) at the exhaust is limited, but the associated protocol developed by the Particle Measurement Program (PMP) group defined a counting efficiency at the 23 nm cutoff particle diameter to avoid measurement artefacts [1][2]. Recent studies have demonstrated that the last generation Euro 6 engines can emit as many particles in the range 10-23 nm as beyond 23 nm [3]. The SUREAL-23 project (Understanding, Measuring and Regulating Sub-23 nm Particle Emissions from Direct Injection Engines Including Real Driving Conditions), funded by Horizon 2020 EU-program, aims to develop sampling, conditioning and measuring instruments and associated methodologies to extend the existing protocol down to at least 10 nm. This measurement setup was evaluated on various light duty direct injection platforms. This communication focuses on a gasoline-DI vehicle with a Euro 6b engine. Tests were conducted on multiple operating conditions (moderate and aggressive driving cycles, hot and cold starts, and several fuel and lubricant formulations). Sampling and conditioning were done with a two-stage dilution system, with a built-in catalytic stripper. The prototype instruments have been compared to commercial reference soot particle analyzers (TSI CPC, Horiba MEXA-2000 SPCS and Cambustion DMS500). A good consistency between all the measurements was demonstrated, with a satisfactory repeatability and robustness of the proposed measurement setup and of the associated methodology. An on-board version of the proposed setup is currently being developed to allow PN measurement in Real Driving Emissions (RDE) conditions.
Modeling of Particle Size Distribution at the Exhaust of Internal Combustion Engines
SpringerBriefs in Applied Sciences and Technology, 2017
Nowadays, the interest in the effect of exhaust emissions from road vehicles on public health is stronger than ever. Great attention is paid to particulate matter (PM) both for its impact on the environment and for the adverse effect on human health. The internal combustion engines (ICEs), both spark ignition (SI), and compression ignition (CI) are the main sources of PM emissions in the urban area. Particles are usually classified according to their diameter in coarse particles, diameter larger than 10 lm (PM10) and fine particles, diameter smaller than 2.5 lm (PM2.5). Further distinction is made for PM2.5, particles smaller than 100 nm are called ultrafine particles and those smaller than 50 nm are called nanoparticles. The chemical nature of the particles as well as the number and size depends on the engine type. Diesel engine particles consist mainly of agglomerated carbonaceous primary particles on which volatile organic material is adsorbed. The gasoline particles, instead, are mainly composed of organic fraction. Both CI and SI engines emit mainly particles in the ultrafine size range. Anyway, the particles' emissions from gasoline direct injection (GDI) engines are higher than that for port fuel injection (PFI) engines and Diesel engines equipped with a Diesel particulate filter (DPF). The severe adverse effects on human health of fine and ultrafine particles emitted from internal combustion were well described in the literature [1-3]. Recent studies evidenced the strict relation between the particle size and the impact on heart and brain [4]. Smaller particles can, in fact, penetrate more easily the cell membranes than large particles [5]. Considering the negligible weight of the fine particle, a particle number (PN) emission limit is enforced in addition to the PM mass emission limits for particles larger than 23 nm at the Euro 6 (2014) for all categories of light-duty (LD) DI vehicles. Great efforts are paid to reduce the particle emissions. Several solutions are under study, regarding the optimization of the combustion and the use of biofuel to reduce particle formation as well as the improvement of after-treatment devices for the reduction of emissions at the exhaust. In any case, availability of real-time information on the characteristics of particulate emissions, such as particle number and size, would enable the development of advanced closed-loop control
Journal of KONES. Powertrain and Transport
Transport is a major source of the particle pollution (PM). Combustion engine particulate emissions have the potential cause adverse health effects. These effects include cancer and other pulmonary and cardiovascular diseases. A substantial proportion of the number of particles, but not the mass, is ultrafine. For example-one million particles of 100 nanometers size with a unit density of 1 g/cm3 have a mass of approximately 0.0005 g. The paper includes research results of mass and number concentration of nanoPM for 1.9 TDI VW exhaust gases fuelled by standard diesel. The measurements were performed for ambient air and 3 different point of engine work (idle speed, low and high load at 2000 rpm). For nanoPM measurements was used Electrical Low Pressure Impactor ELPI from DECATI, was found, among other things, that the biggest mass concentration was at 0.1-10 m of PM diameter but the biggest number concentration was at 0,01-0,1 m and thus for the size of solid particles of at least an order of magnitude smaller than the mass concentration. The biggest the negative differences in the mass concentration occur in the exhaust gases of the RME fuelled engine (in comparison with diesel fuel) at engine idling when the smallest injection pressure and temperature inside the engine cylinder exist and the oxygen availability is also the lowest (because of the small charging pressure and high EGR rate). Such measurements are important not only in terms of utilitarian but also in cognitive sense-for determining the effect of the engine construction parameters and/or regulating the engine (or the fuel composition) on the mass and the number of nanoparticles emitted in the exhaust gases.
Particle Emission Measurements from L-Category Vehicles
SAE International Journal of Engines, 2015
In 2011 a particle number (PN) limit was introduced in the European Union's vehicle exhaust legislation for diesel passenger cars. The PN method requires measurement of solid particles (i.e. those that do not evaporate at 350 °C) with diameters above 23 nm. In 2013 the same approach was introduced for heavy duty engines and in 2014 for gasoline direct injection vehicles. This decision was based on a long evaluation that concluded that there is no significant sub-23 nm fraction for these technologies. In this paper we examine the suitability of the current PN method for L-category vehicles (two-or three-wheel vehicles and quadri-cycles). Emission levels of 5 mopeds, 9 motorcycles, 2 tricycles (one of them diesel) and 1 quad are presented. Special attention is given to sub-23 nm emission levels. The investigation was conducted with PN legislation compliant systems with particle counters measuring above 23 nm and 10 nm. In addition other approaches using catalytic strippers and counters from 3 nm or particle sizers were used to confirm the nature of the particles. The results showed that there is a significant portion of solid particles not counted with the current PN method. On the other hand, the high amount of volatile material can lead to artifacts below 23 nm, and thus great care has to be taken when measuring the PN of this category.