Higher Particulate Matter Emissions Research Articles

Key Performance Indicators for Decision Support in Building Retrofit Planning: An Italian Case Study

To achieve climate and energy goals in the building sector, the current pace of renovating existing structures must double, overcoming prevailing barriers. Key Performance Indicators play a pivotal role in science-based decision making, emphasizing both direct and indirect benefits of building retrofits. The authors aim to contribute to proper metric identification for multi-perspective building performance assessment and formulate a methodology supporting energy planning decisions. They introduce the Global Cost per Emission Savings (GCES), an aggregated indicator encompassing both public (CO2 emissions) and private (global cost) perspectives of diverse retrofit technologies for building HVAC systems. Applied to the Italian residential building stock via the Reference Building approach, the methodology is tested using condensing gas boilers, biomass boilers, and electric heat pumps, revealing diverse environmental and economic performances. Addressing the establishment of effective decision-support tools for policymakers, the paper explores the potential impact of various policies on the favorability of technologies. Different policy scenarios are delineated to analyze how distinct approaches may influence the attractiveness of technologies. Notably, in the baseline scenario, biomass boilers hold an advantage over heat pumps according to the GCES index. However, scenarios involving technology-specific incentives or a greenhouse gases emission tax failed to alter the technological ranking, leaving heat pumps financially uncompetitive. In contrast, the TXPM scenario positions heat pumps as the most financially appealing option, penalizing biomass boilers for high particulate matter emissions.

NUMERICAL STUDY OF DIRECT INJECTION SPRAY BEHAVIOR OF GASOLINE AND METHANOL-GASOLINE BLENDS UNDER SPLIT-INJECTION STRATEGY IN ENGINE-LIKE CONDITIONS

Several studies have shown that the split-injection strategy has improved the shortcomings of the high particulate matter emissions and cycle-to-cycle variations in homogeneous and stratified combustion modes of gasoline direct injection (GDI) engines. However, the spray behavior under the split injection strategy is poorly understood. This study uses computational fluid dynamics (CFD) simulations in Converge software to investigate the spray characteristics of gasoline and methanol-gasoline blends under a split-injection strategy. The simulation studies were performed for a multihole GDI injector in a constant volume spray chamber, replicating the ambient conditions similar to a GDI engine's homogeneous and stratified combustion modes. Appropriate models for simulating different spray phenomena, such as spray breakup, collision, and coalescence, were used. The CFD model was validated using the experimental spray penetration length provided in the engine combustion network database. The results showed that the split-injection reduced the Sauter mean diameter (SMD) of fuel spray droplets and liquid fuel mass content than a single injection case. The dwell time of 2 ms was found suitable for homogeneous mode conditions, while its effect was insignificant in stratified mode conditions. Further, a split ratio of 80:20 resulted in smaller SMD during the injection period and a higher fuel evaporation rate. The effect of methanol addition was also explored under the split-injection mode. M85 showed higher deviations in the liquid spray penetration, SMD, and liquid spray mass content than G100.

Effect of treadwear grade on the generation of tire PM emissions in laboratory and real-world driving conditions

Tires generally wear out due to the friction between the tire and the road surface. Minimizing tire wear could reduce the non-exhaust particulate matter (PM) emissions from tires. Typically, tire treadwear grade can be used as an indicator of PM emissions from tires. Tires that wear out quickly will produce higher PM emissions than more durable tires. In this study, the effect of treadwear grade on the generation of tire PM emissions was investigated through laboratory and on-road driving measurements. In the laboratory measurements, a tire wear simulator installed in an enclosed chamber was used to eliminate artifacts caused by interfering particles during the generation and measurement of tire wear particles. For realistic on-road driving measurements, a mobile sampling vehicle was employed to sample road dust. The road dust was chemically analyzed using pyrolysis gas chromatography–mass spectrometry (GC–MS) to characterize the tire-road wear particles.Both measurements showed that the higher treadwear grade generated lower tire PM emissions due to the high strength of the rubber, except for the UTQG 700 tire. The UTQG 700 tire, which had the highest treadwear grade, produced higher PM emissions than the UTQG 350 and 500 tires because it readily formed the fine particles due to lamellar peeling rather than tearing or curling of tire treads. Notably, tire nanoparticles were observed in laboratory measurements due to the volatilization and nucleation of the sulphur (S) and zinc (Zn) compounds in the tire tread due to the frictional heat between the tire and paved road surface.

Effect of oxidative torrefaction on particulate matter emission from agricultural biomass pellet combustion in comparison with non-oxidative torrefaction

Torrefaction could improve the fuel properties and reduce the operating costs. However, the particulate matter (PM) emission behavior during the torrefied pellet combustion remains unknown. In this work, cotton stalk was torrefied at a temperature of 220–300 °C with a O2 concentration of 0–21%. The torrefied pellet was burned out and PM emission behavior was investigated using a Dekati low-pressure impactor. The results show that oxidative torrefaction leads to notable decreases of H/C and O/C ratios, which makes the fuel properties similar to coals. The heating value is significantly improved and sensitive to the torrefaction temperature. Both non-oxidative and oxidative torrefaction give rise to considerable increase in the yield of PM10. The main composition of PM1 changed from KCl to K2SO4 due to the substantial release of Cl during torrefaction. Meanwhile, Ca and K contents in PM1-10 are generally high, implying that the presence of oxygen can facilitate the transformation of alkali and alkaline-earth metals into coarse particles. The torrefaction temperature at around 260 °C with a low O2 concentration of 0–6% are the optimal torrefaction operation conditions to produce good quality torrefied cotton stalk pellet with respect to high heating value and low PM emission in later combustion application.

Roller dynamometer particle immission* measurement

AbstractUrban traffic is a significant contributor of particulate matter to the environment (Kessinger et al. in https://www.umweltbundesamt.de/sites/default/files/medien/5750/publikationen/hgp_luftqualitaet_2020_bf.pdf, 2021). Hence, there is a high interest in the measured data of roadside immission measurement station. In the federal state Saxony (Germany), the State Office for Environment, Agriculture and Geology (LfULG) is responsible for supervision of the air pollution. In a joint project, the LfULG, the Leibniz Institute for Tropospheric Research (TROPOS) and the Chair of Combustion Engines and Powertrain Systems of the Technical University of Dresden (Lehrstuhl für Verbrennungsmotoren und Antriebssysteme, LVAS) measured the particulate immission* from a selection of passenger cars in an “environment simulation” Weinhold et al. (https://publikationen.sachsen.de/bdb/artikel/36768q, 2020). Especially direct injection spark ignition engines, DISI, without particle filter have a high particulate matter emission, depending on the operating condition. However, an increase of the particulate matter immission due to the rising market penetration of DISI engines was not measurable at the immission measurement stations of LfULG. To investigate the effect of vehicle exhaust emission and immission, an experiment was developed to measure particulate matter immission similar to road conditions on a chassis dynamometer. Five used cars with different engines, exhaust after treatment systems and mileage were evaluated regarding their emissions and particulate immissions. Unexpectedly, a high amount of ultrafine particulate matter smaller 100 nm was found during the emission measurements, although the exhaust emissions were completely extracted to the CVS measurement system. It was concluded that these particles were assignable to break and tire wear. This paper summarizes the most important findings, the complete report is available in Weinhold et al. (https://publikationen.sachsen.de/bdb/artikel/36768q, 2020).

Indoor Air Pollution Exposure of Women in Adama, Ethiopia, and Assessment of Disease Burden Attributable to Risk Factor.

Introduction and aim: Air pollution, a major environmental threat to human health, contributes to the premature deaths of millions of people worldwide. Cooking with solid fuels, such as charcoal and wood, in low- and middle-income countries generates very high emissions of particulate matter within and near the household as a result of their inefficient combustion. Women are especially exposed, as they often perform the cooking. The purpose of this study was to assess the burden of disease attributable to household air pollution exposure from cooking among women in Adama, Ethiopia. Methods: AirQ+ software (WHO Regional Office for Europe, Copenhagen, Denmark) was used to assess the health impact of household air pollution by estimating the burden of disease (BoD) including Acute Lower Respiratory Infections (ALRI), Chronic Obstructive Pulmonary Disease (COPD), Ischemic Heart Disease (IHD), lung cancer, and stroke, among a cohort of women in Adama. Household air pollution exposure estimated by cooking fuel type was assessed through questionnaires. Results: Three-quarters (75%) of Adama’s population used solid fuel for cooking; with this, the household air pollution attributable mortality was estimated to be 50% (95% CI: 38–58%) due to ALRI, 50% (95% CI: 35–61%) due to COPD, 50% (95% CI: 27–58%) due to lung cancer, (95% CI: 23–48%) due to IHD, and (95% CI: 23–51%) due to stroke. The corresponding disability-adjusted life years (DALYs) per 100,000 women ranged between 6000 and 9000 per disease. Conclusions: This health impact assessment illustrates that household air pollution due to solid fuel use among women in Adama leads to premature death and a substantial quantity of DALYs. Therefore, decreasing or eliminating solid fuel use for cooking purposes could prevent deaths and improve quality of life.

Development of a simple and rapid test method for potassium (RAPPOD) to ensure fuel quality of woody biomass fuels

Elevated contents of potassium in low quality residues from forestry and agriculture are recognized as main reason for high particulate matter emissions and an increased slagging risk in the bottom ash during utilization of these assortments. Determination of potassium content with reliable rapid and simple test methods could contribute to an appropriate selection and optimum use of biomass for combustion, gasification, and pyrolysis. A cheap soil analysis test kit with investment costs below 1000 € was used to determine potassium contents in different wood assortments. Sample preparation (e.g. particle size) as well as the analysis procedure (e.g. dilution rates, solution agents, and analysis time) were adapted to the requirements for the analysis of the biomass matrix. Activated carbon had to be added to the reagent to improve the precision of the analysis method. The rapid test method is most suitable for potassium contents between 500 and 2000 mg·kg−1 d.b. Potassium contents higher than 2000 mg·kg−1 d.b. can be well detected though with a higher variance. Reliable results were achieved within 10 min analysis time and low cost of about 5 € per sample (consumables). Measurement accuracy was evaluated using ICP-OES analysis of the fuels after digestion with hydrofluoric acid and reveals an overall underestimation of the potassium content though on a comparable level over the whole analysis range.

High particulate matter burden by cigarillos: A laser spectrometric analysis of second-hand smoke of common brands with and without filter.

Although the global tobacco market of cigarillos is substantial, little is known about their particulate matter (PM) emissions. For exposure risk assessment of cigarillos, the PM fractions PM10, PM2.5, and PM1 of eight cigarillo brands (four with filters) and a reference cigarette were measured. For this purpose, second-hand smoke was generated by an automatic smoke pump in a measuring chamber with a volume of 2.88 m³. The mean particle concentrations of the cigarillos ranged from 2783 μg/m³ to 6686 μg/m³ for PM10, from 2767 μg/m³ to 6585 μg/m³ for PM2.5, and from 2441 to 4680 μg/m³ for PM1. Mean concentrations of the reference cigarette for PM10, PM2.5, and PM1 were 4400 μg/m³, 4335 μg/m³, and 3289 μg/m³, respectively. Filter-tipped cigarillos showed between 5% and 38% lower PM10 and PM2.5 levels, respectively, and between 4% and 30% lower PM1 levels. Our findings show generally high PM emissions for all investigated tobacco products. Therefore, the declaration of PM amounts to government authorities should be mandatory for all tobacco products. Policymakers should ensure that corresponding information will be provided in the future.

Particulate matter emissions from flex-fuel vehicles with direct fuel injection

Otto cycle vehicles with gasoline direct injection (GDI) can reduce fuel consumption by 5–20%. In compliance with current legislation in Brazil, this technology was introduced to the domestic market in the form of a first flex-fuel GDI vehicle in 2013. However, despite gains in efficiency, studies in the literature have shown that GDI engines tend to have higher particulate matter emissions than port fuel injection (PFI) engines. This paper provides measurements of the emissions of GDI flex-fuel vehicles fuelled with gasoline containing 22% anhydrous ethanol (E22), hydrous ethanol (E100) and a 50% mixture of both (E61). The blending fuels were tested in accordance with the recommendations made in the widely known FTP 75 and HWFET cycles. The particulate-matter emissions formed during the combustion process were closely linked to fuel-type properties. The results showed the particles that adhere to sampling filters have higher concentrations of fluorine and carbon and lower amounts of silicon and oxygen, as well as sizes of around 2 μm. The black carbon emissions tend to increase directly with the gasoline content in the fuel. The results also provided evidence that the HWFET test cycle showed a higher emission rate of total particulate matter than the FTP 75 test cycle, and that overall, there were higher emissions for E22 than E100.

Property predictions demonstrate that structural diversity can improve the performance of polyoxymethylene ethers as potential bio-based diesel fuels

High emissions of particulate matter from diesel engines presents a serious risk to human health and the environment. The addition of oxygenated molecules to diesel fuels has been shown to reduce soot formation during combustion. Polyoxymethylene ethers (POMEs) are a novel class of oxygenated molecules that can be produced from biomass and that have the potential to be used as soot-reducing diesel fuel blendstocks. However, only a few variations of these molecules have been studied thus far, and those that have been characterized present significant disadvantages that could compromise current liquid fuel systems and diesel engines. Using a variety of structure–activity models, we evaluated 67 POMEs to predict the effects of structural variations on important fuel properties. Prediction accuracy was assessed by comparing predictions with measurements for a subset of structures. Nine POME molecules were identified as having potential to reduce soot formation by over 75% compared to conventional diesel fuels while being compatible with current liquid fuel infrastructure, maintaining optimal engine performance, and presenting a minimal risk to the environment. None of these nine POMEs has been previously identified as a potential diesel blendstock. This is the first evaluation of POMEs as a class of molecules and the results guide research on the synthesis, properties, and engine performance of POMEs.

Impact of Aromatic Structures and Content in Formulated Fuel for Jet Engine Applications on Particulate Matter Emissions

Abstract Fuel formulation with the particular selection of fuel components is a promising approach that offers the reduction of harmful emissions without altering the combustion system performance. Each fuel component has its own combustion characteristics and hence contribution to emissions. Aromatic is one of the main components of fossil-based fuels and has a strong correlation with the formation of particulate matter (PM) emissions. Besides, aromatics presence in fuel is essential for the compatibility of fuel with the combustion system and maintaining the energy density of the fuel. In this regard, a Rolls-Royce combustor rig was used to test 16 aromatics blended with jet fuels in three different proportions. Moreover, a novel approach of flame luminosity imaging is employed to measure the PM emissions through the soot propensity profile. The results show that PM emissions increase with the proportional increase of aromatics. The di- and cyclo-aromatics produced significantly higher PM emissions compared to alkyl-benzenes. 3-Isopropylcumene tends to lowest PM formation and thus is a consideration as a selection of aromatic type in future fuels for lower PM emissions. Furthermore, it was also observed that PM number concentration measured by the extractive method with DMS 500 instrument correlates well with imaging methods for all the tested fuels. The present study provides information on particular selection of aromatic for future fuel development.

Analysis of out-of-round deformation of a dry cylinder liner of a non-road high-pressure common-rail diesel engine based on multi-field coupling

The deformation of cylinder liner directly affects the sealing performance of the friction components in internal combustion engines, resulting in high oil consumption, engine power loss, and high-particulate matter emissions. Previous research works focused more on deformation of the wet vehicular cylinder liners, however, the effects of different loads on the dry liner deformation is not clear yet. A non-road high-pressure common-rail diesel engine was selected as the research object, and a coupled model of the engine was developed based on fluid–solid coupled heat transfer theory. After the accuracy of the model was verified by temperature measurement of the cylinder head and cylinder liner, deformation of the dry cylinder liner was studied. The results show that the axial and radial deformations of the cylinder liner are not uniform under the bolt preload condition. Large deformation occurs at the first liner and fourth liner, with the maximum deformation occurring at the top of fourth liner for 10.14 μm. Under the condition of thermal load, the temperature of cylinder liner exhibits a distribution of three-segments from the top to bottom. The liner deformation is not uniform, and the maximum deformation occurs at the top of the fourth liner for 304 μm. The radial deformations of all four cylinder liners present a symmetrical structure of a “heart” shape with respect to the centerline of the second and third cylinders. The axial deformation of each liner exhibits a “barrel” shape which is convex in the middle and narrow at the two ends.

Soot contamination of engine oil – the case of a small turbocharged spark-ignition engine

The paper presents the results of thermogravimetric tests of engine oil used in a small turbocharged spark-ignition engine. The main observation from the research was a significant soot contamination of engine oil, that appears even at its low mileage. This indicates that also in the case of port fuel injection spark-ignition engine, high particulate matter emissions may occur. It may therefore turn out that the small city car can be more harmful to the environment than much larger vehicles. A rapid soot contamination of the oil in this engine indicates as well that the oil change interval should be shortened.

The effect of particulate matter on solar photovoltaic power generation over the Republic of Korea

Degradation in air quality could be a potential factor for decreasing solar photovoltaic (PV) power generation. However, our understandings of the potential of airborne particulate matter (PM) to reduce actual solar PV power generation remain unclear. This study quantifies attenuation impacts of airborne PM on solar PV power generation on cloudless days at Yeongam and Eunpyeong-gu power plants installed in the Republic of Korea. The reduction rate of solar PV power generation according to the substantial amount of PM is calculated by constructing multiple regression models based on actual solar PV power generation record, observed meteorological parameters, and measured PM2.5 and PM10 concentrations for 2015–2017. At both power plants, PM2.5 and PM10 commonly reduce solar PV power generation by more than 10% of the maximum capacity under the conditions of ‘normal’ air quality, 35 μg m−3 and 80 μg m−3 for PM2.5 and PM10, respectively. Moreover, the reduction rate of solar PV power generation exceeds 20% of the maximum capacity under ‘bad’ air quality, 75 μg m−3 and 150 μg m−3 for PM2.5 and PM10, respectively. Results show that the negative impacts of PM on solar PV power generation should be considered in the process of policymaking on target solar power generation in Korea, as well as in countries with high PM emissions.

Split Injection Strategies for Biodiesel-Fueled Premixed Charge Compression Ignition Combustion Engine—Part II: Particulate Studies

Abstract In this study, experiments were performed in a single-cylinder research engine to investigate the particulate matter (PM) characteristics of the engine operated in premixed charge compression ignition (PCCI) mode combustion vis-a-vis baseline compression ignition (CI) mode combustion using three test fuels, namely, B20 (20% v/v biodiesel blended with mineral diesel), B40 (40% v/v/ biodiesel blended with mineral diesel), and baseline mineral diesel. The experiments were carried out at constant fuel injection pressure (FIP) (700 bar), constant engine speed (1500 rpm), and constant fuel energy input (0.7 kg/h diesel equivalent). PM characteristics of PCCI mode combustion were evaluated using two different fuel injection strategies, namely, single pilot injection (SPI) (35 deg before top dead center (bTDC)) and double pilot injection (DPI) (35 deg and 45 deg bTDC) at four different start of main injection (SoMI) timings. Results showed that both PCCI mode combustion strategies emitted significantly lower PM compared to baseline CI mode combustion strategy. However, the blending of biodiesel resulted in relatively higher PM emissions from both CI and PCCI combustion modes. Chemical characterization of PM showed that PCCI mode combustion emitted relatively lower trace metals compared to baseline CI mode combustion, which reduced further for B20. For detailed investigations of particulate structure, morphological characterization was done using transmission electron microscopy (TEM), which showed that PM emitted by B20-fueled PCCI mode combustion posed potentially lower health risk compared to baseline mineral diesel-fueled CI mode combustion.

Top-down vehicle emission inventory for spatial distribution and dispersion modeling of particulate matter.

Emission inventories are one of the most critical inputs for the successful modeling of air quality. The performance of the modeling results is directly affected by the quality of atmospheric emission inventories. Consequently, the development of representative inventories is always required. Due to the lack of regional inventories in Brazil, this study aimed to investigate the use of the particulate matter (PM) emission estimation from the Brazilian top-down vehicle emission inventory (VEI) of 2012 for air quality modeling. Here, we focus on road vehicles since they are usually responsible for significant emissions of PM in urban areas. The total Brazilian emission of PM (63,000tyear-1) from vehicular sources was distributed into the urban areas of 5557 municipalities, with 1-km2 grid spacing, considering two approaches: (i) population and (ii) fleet of each city. A comparison with some local inventories is discussed. The inventory was compiled in the PREP-CHEM-SRC processor tool. One-month modeling (August 2015) was performed with WRF-Chem for the four metropolitan areas of Brazilian Southeast: Belo Horizonte (MABH), Great Vitória (MAGV), Rio de Janeiro (MARJ), and São Paulo (MASP). In addition, modeling with the Emission Database for Global Atmospheric Research (EDGAR) inventory was carried out to compare the results. Overall, EDGAR inventory obtained higher PM emissions than the VEI segregated by population and fleet, which is expected owing to considerations of additional sources of emission (e.g., industrial and residential). This higher emission of EDGAR resulted in higher PM10 and PM2.5 concentrations, overestimating the observations in MASP, while the proposed inventory well represented the ambient concentrations, obtaining better statistics indices. For the other three metropolitan areas, both EDGAR and the VEI inventories obtained consistent results. Therefore, the present work endorses the fact that vehicles are responsible for the more substantial contribution to PM emissions in the studied urban areas. Furthermore, the use of VEI can be representative for modeling air quality in the future.

RS&GIS based PM emission inventories of dust sources over a provincial scale: A case study of Henan province, central China

Henan province, the most populous province in China, is facing serious particulate matter (PM) pollution problem. In this study, a provincial emission inventory of total suspended particles (TSP), particulate matter 10 (PM10) and particulate matter 2.5 (PM2.5) from dust source of the year 2016 was established on a grid of 3 km × 3 km resolution using the RS and GIS technology. The results show that the TSP, PM10 and PM2.5 emission from dust source in Henan province were 1261.11 kt·a−1, 461.24 kt·a−1 and 103.05 kt·a−1, respectively. Among various emission sources, construction dust was the main sources of PM emission, which contributes 56.72% of the TSP emission, 77.68% of the PM10 emission and 76.77% of the PM2.5 emission. Furthermore, the total emission of TSP, PM10 and PM2.5 in Henan province formed a Zhengzhou-centered high emission zone, which was surrounded by Luoyang, Kaifeng, Xinxiang, Jiaozuo and Xuchang cities. PM emission from different dust sources showed particular spatial characteristics, high PM emission of soil dust source was more likely to occur in cities with backward economic development and dry climate, PM emission of construction dust source mainly concentrated in developed and densely populated regions, city centers and the surrounding country centers were the area with high PM emission from road dust source.

Characteristics and formation mechanism of a serious haze event in autumn 2017 in Harbin, China

Eighteen air quality monitoring stations in nine districts and nine counties in Harbin were selected to analyze the spatial and temporal characteristics of six basic air pollutants. Straw burning monitoring data, meteorological factor data, and aerosol optical depth (AOD) data were selected in combination with backward trajectory of hybrid single particle lagrangian integrated trajectory (HYSPLIT) to analyze the causes of air pollution. The results showed that the daily variation of the six pollutants was consistent with the three haze processes, and the main pollutants were particulate matter 2.5 (PM2.5) and particulate matter 10 (PM10). Except for O3, the hourly variations in the concentrations of other pollutants showed the same patterns over time. The concentrations increased at night and gradually decreased during the day. The most polluted areas were the urban area and the central area of Harbin, among which the worst was the Shuangcheng District. The cause of the pollution is as follows: First, there are a large number of straw burning areas surround Harbin, which cause high particulate matter emission. Second, the weak air pressure and low wind speed limit pollutant diffusion, allowing gradual accumulation, resulting in a high concentration of particles near the ground. Finally, regional pollutant transport from the southwest also contributes to the pollution process.

Combustion and emission characteristics of gasoline/hydrogenated catalytic biodiesel blends in gasoline compression ignition engines under different loads of double injection strategies

Gasoline compression ignition mode is one of the low-temperature combustion strategies using gasoline instead of diesel fuel and it is better than the other low-temperature combustion modes in terms of ignition controllability. Difficulty in the ignition at low loads and maximum pressure rise rate during high loads is the main problem in commercializing this engine. In order to solve this problem, hydrogenated catalytic biodiesel is blended with gasoline in different proportions and its combustion and emission characteristics under different working loads are investigated in a single injection mode. Stable combustion is achieved using this gasoline/hydrogenated catalytic biodiesel blends without any combustion assistance and increasing intake temperature. Results show that G70H30 blending fuel illustrates a comprehensively better combustion and emissions performance. However, the high maximum pressure rise rate at high loads and high particulate matter emission are the main problems. Hence, multiple injection strategies are applied for G70H30 to solve the above problem. It reveals that the particulate matter emission for 20% pilot injection ratio is lower than that of single injection mode. The maximum pressure rise rate of 20% or 30% pilot injection ratio can meet the engine limit. While the carbon monoxide and hydrocarbons emissions for double injection mode are higher than that of single injection mode and it increases with increasing pilot injection ratio.

Impacts of gasoline aromatic and ethanol levels on the emissions from GDI vehicles: Part 2. Influence on particulate matter, black carbon, and nanoparticle emissions

Fuel composition plays an important role on the particulate matter (PM) emissions formation from gasoline direct injection (GDI) engines. In this study, the impacts of gasoline chemical structure and physical properties on the particulate emissions were assessed for a fleet of five Tier 3 compliant GDI vehicles. All vehicles were tested on eight fuels with varying aromatic and ethanol levels, as well as varying PM indices (PMIs) over the LA92 test cycle in at least duplicate on each of the test fuels. Our results showed strong, statistically significant fuel differences for the weighted PM mass emissions and all three phases of the LA92 cycle. The higher aromatic content fuels showed increases in PM mass and black carbon emissions that were statistically significant compared to the lower aromatic fuels. The fuels with higher PMIs showed an upward, but not statistically significant, trend for PM mass emissions with increasing ethanol content likely due to ethanol’s evaporative charge cooling effect. This observation does not hold true for the lower PMI fuels. Similar trends to the weighted PM mass emissions were also seen for the cold-start and hot-running PM mass emissions, as well as for the weighted black carbon emissions, indicating a possible ethanol reinforcing effect on PM formation for the high PMI fuels. Total and solid particle number emissions also showed increases with the higher aromatic fuels compared to the lower aromatic fuels. Similar to PM mass, both total and solid particle number emissions demonstrated an upward trend for the high PMI fuels with an increase in ethanol content. While the study is consistent with other studies showing that increasing aromatics and PMI values lead to higher PM emissions, the results also suggest that this relationship is complicated by the presence of varying levels of ethanol in high aromatic and PMI fuels, where increasing levels of ethanol in these fuels can also lead to PM increases. High molecular weight and low volatility hydrocarbon species (especially aromatics) also strongly impacted particulate emissions formation in GDI vehicles.