Gasoline Exhaust Research Articles

Microstructural Characterization of Particulate Matter from Gasoline-Fuelled Vehicle Emissions

Exhaust emissions from vehicle traffic refers to the particles released into the air due to combustion of fuels, additives and wear of engine parts in the system during vehicle use. These emissions occur depending on the type of vehicle, type of fuel, combustion process and environmental conditions. In this study, microstructure and chemical characterization of particulate matter (PM) released from gasoline-fuelled vehicles were examined using electron microscopy techniques. As a result, much solid soot, metalloids, heavy metals, ash, sulphates, phosphates, minerals, volatile organic and inorganic pollutants were found to be present in gasoline exhaust emission. These toxic structures still pose a danger to environmental safety and human health.
 Aim: In study, microstructure characterization of emissions released from gasoline-fuelled vehicles exhaust were investigated using electron microscopy techniques. Study design: SEM, EDS, XRD and FTIR electron microscopy techniques were used for characterization.
 Place and Duration of Study: Material Characterization Laboratory of Karamanoğlu Mehmetbey University, Scientific and Technological Research Application and Research Center, between Junuary 2020 and July 2020.
 Results: The vehicles still continue to spread toxic pollutants.
 Conclusions: The chemical structure of PM contains 20 elements including C, F, N, Na, O, Mg, Br, Si, Hg, S, P, Pb, Ca, Cr, Mn, Fe, Ni, Co, Cu, Zn. There are pollutant functional groups such as OH, CO, SO in the structure. Hydrocarbons, metalloids, heavy metals, different minerals, phosphates, sulfates, many volatile organic and inorganic compounds pollute the air in PM structure. These toxic pollutants harm the environment and human health.

Seasonal pollution characteristics, source apportionment and health risks of PM2.5-bound polycyclic aromatic hydrocarbons in an industrial city in northwestern China

PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) have attracted considerable attention due to their carcinogenicity to humans. As the “copper city” of China, Baiyin has unique natural geographical conditions, but there have been few studies on PM2.5-bound PAHs pollution characteristics. Therefore, the pollution characteristics, sources and health risks of PM2.5-bound PAHs in Baiyin were studied over a one-year period. The average annual PAHs concentration was 67.4 ± 34.7 ng/m3, with the highest PAHs concentration in winter and the lowest in summer. Based on a positive matrix factorization (PMF) model, the main PAHs sources were coal, a mixed source of petroleum volatilization and natural gas and biomass combustion, gasoline exhaust, and diesel exhaust. Spring and winter were dominated by coal combustion, while summer and autumn were dominated by gasoline exhaust. Backward trajectory analysis showed, that the largest pollution contribution came from the local area throughout the year, followed by northern Mongolia in spring, northeastern Xinjiang in summer, and Qinghai in autumn and winter. A human carcinogenic risk assessment based on a health model indicated that PAHs emissions should be controlled in seasons other than summer, especially when there is a risk of ingestion and dermal contact.

Source apportionment of PM2.5 at two Seattle chemical speciation sites

ABSTRACT Positive Matrix Factorization analysis of PM2.5 chemical speciation data collected from 2015–2017 at Washington State Department of Ecology’s urban NCore (Beacon Hill) and near-road (10th and Weller) sites found similar PM2.5 sources at both sites. Identified factors were associated with gasoline exhaust, diesel exhaust, aged and fresh sea salt, crustal, nitrate-rich, sulfur-rich, unidentified urban, zinc-rich, residual fuel oil, and wood smoke. Factors associated with vehicle emissions were the highest contributing sources at both sites. Gasoline exhaust emissions comprised 26% and 21% of identified sources at Beacon Hill and 10th and Weller, respectively. Diesel exhaust emissions comprised 29% of identified sources at 10th and Weller but only 3% of identified sources at Beacon Hill. Correlation of the diesel exhaust factor with measured concentrations of black carbon and nitrogen oxides at 10th and Weller suggests a method to predict PM2.5 from diesel exhaust without a full chemical speciation analysis. While most PM2.5 sources exhibit minimal change over time, primary PM2.5 from gasoline emissions is increasing on average 0.18 µg m−3 per year in Seattle. Implications This study utilizes Positive Matrix Factorization to determine PM2.5 sources from chemical speciation measurements at two urban Seattle sites from 2015-2017. The paper reports PM2.5 source trends, and extends previous source apportionment analyses in Seattle to the present day. The study also quantifies diesel PM2.5 at a near-road site, and describes a predictive model that allows estimation of the contribution of diesel PM2.5 to the total measured PM2.5 at near-road sites across the country without a full chemical speciation analysis.

Characteristics of atmospheric volatile organic compounds in urban area of Beijing: Variations, photochemical reactivity and source apportionment

Atmospheric volatile organic compounds (VOCs) were observed by an on-line gas chromatography-flame ionization detector monitoring system from November 2016 to August 2017 in Beijing. The average concentrations were winter (40.27 ± 25.25 μg/m3) > autumn (34.25 ± 19.90 µg/m3) > summer (32.53 ± 17.39 µg/m3) > spring (24.72 ± 17.22 µg/m3). Although benzene (15.70%), propane (11.02%), ethane (9.32%) and n-butane (6.77%) were the most abundant species, ethylene (14.07%) and propene (11.20%) were the key reactive species to ozone formation potential (OFP), and benzene, toluene, ethylbenzene, m-xylene + p-xylene and o-xylene (54.13%) were the most reactive species to secondary organic aerosol formation potential (SOAFP). The diurnal and seasonal variations indicated that diesel vehicle emission during early morning, gasoline vehicle emission at the traffic rush hours and coal burning during the heating period might be important sources. Five major sources were further identified by positive matrix factorization (PMF). The vehicle exhaust (gasoline exhaust and diesel exhaust) was found to be contributed most to atmospheric VOCs, with 43.59%, 41.91%, 50.45% and 43.91%, respectively in spring, summer, autumn and winter; while solvent usage contributed least, with 11.10%, 7.13%, 14.00% and 19.87%, respectively. Biogenic emission sources (13.11%) were only identified in summer. However, both vehicle exhaust and solvent usage were identified to be the key sources considering contributions to the OFP and SOAFP. Besides, the contributions of combustion during heating period and gasoline evaporation source during warm seasons to OFP and SOAFP should not be overlooked.

Source apportionment of hourly-resolved ambient volatile organic compounds: Influence of temporal resolution

High temporal-resolution VOC concentration data can provide detailed and important temporal variations of VOC species and emission sources, which is not possible when using coarse temporal-resolution data. In this study, we utilized the positive matrix factorization (PMF) model to conduct source apportionment of hourly concentrations of nineteen VOC species and CO measured at the Mong Kok air quality monitoring station, operated by the Hong Kong Environmental Protection Department, from January 2013 to December 2014. The PMF analysis of the hourly dataset (PMF_Hourly) identified five sources, including liquefied petroleum gas (LPG) (contribution of 45%), gasoline exhaust (21%), combustion (20%), biogenic emission (9%), and paint solvents (6%). The diurnal patterns of VOC emissions from identified sources are likely to be affected by the strength of emissions, variation of the planetary boundary layer height, and photochemical reactions. In addition, the PMF analyses of hourly and 24-hour averaged data of the hourly-resolved data (PMF_Hourly and PMF_Daily) were generally comparable, but the time series of VOC emissions from PMF_Hourly could not be well captured by PMF_Daily for two local VOC sources of gasoline exhaust and LPG. This study highlights the benefit of high temporal-resolution measurement data in apportioning VOC sources, hence providing critical information on VOC emission sources (e.g., diurnal variations) for controlling VOC emissions effectively.

Minimizing secondary pollutant formation through identification of most influential volatile emissions in gasoline exhausts: Impact of the vehicle powertrain technology

Despite the growing share of hybrid vehicles in worldwide vehicle fleet, the impact of battery/engine switch on secondary pollutant precursors formation remains poorly understood. We herein identify the species to be removed primarily from the exhaust of hybrid vehicles to minimize secondary pollutants formation. Pollutants from a conventional (thermal) and a hybrid vehicle are herein evaluated in a chassis dynamometer bench by using two widely used driving cycles, WLTC and FTP75. Hybrid vehicle exhibits the lowest regulated emissions during all the different tests, except for NOx. The results reveal that low and cold start phases of the cycles contribute mainly to the ozone potential, although methane, butadiene and formaldehyde can be emitted at the tailpipe all along the driving cycle. We evidence for the first time a significant contribution of gas-phase reactions to butadiene and methane production inside the exhaust pipe, especially during warm restarts and accelerations. This study indicates that pollutant traps should target primarily monoaromatics which contribute typically to 40% of photochemical ozone creation and 50% to Secondary Organic Aerosols (SOA). However, the contribution of alkanes to ozone differs markedly for the hybrid vehicle, reflecting a different share of ozone production paths with respect to conventional vehicles.

Effect of gasoline-like fuel obtained from hard-resin of Yang (Dipterocarpus alatus) on single cylinder gasoline engine performance and exhaust emissions

This study focused on the performance and exhaust emissions of gasoline engines using gasoline-like fuel (GLF) produced from hard-resin of Yang (HY) by the fast pyrolysis process in semi-continuous reactors at pyrolysis temperature of 500 °C. Bio-oil products obtained from the process were distilled into heavy fuel at 200–350 °C and light fuel at 25–200 °C. HY (100%wt) generated 20.5%wt of light fuel and 30.8%wt of heavy fuel with 35.0%wt of gas and 13.7%wt of waste obtained. Light fuel as well as GLF and gasoline were tested for distillation, density, viscosity, heating value, flash point and silver strip corrosion under ASTM and also for the effect of GLF on performance and exhaust emissions of spark-ignition (SI) engines for a four-stroke single cylinder and fuel mixing system with carburetor. Positive results were shown for performance of brake torque, brake power and brake thermal efficiency. Findings revealed that brake specific fuel consumption was lower compared to gasoline. Carbon monoxide (CO) and hydrocarbon (HC) from engine exhaust were lower than gasoline with carbon dioxide (CO2) and nitrogen oxides (NOx) higher.

A Spatial-Temporal Resolved Validation of Source Apportionment by Measurements of Ambient VOCs in Central China.

Understanding the sources of volatile organic compounds (VOCs) is essential in the implementation of abatement measures of ground-level ozone and secondary organic aerosols. In this study, we conducted offline VOC measurements at residential, industrial, and background sites in Wuhan City from July 2016 to June 2017. Ambient samples were simultaneously collected at each site and were analyzed using a gas chromatography–mass spectrometry/flame ionization detection system. The highest mixing ratio of total VOCs was measured at the industrial site, followed by the residential, and background sites. Alkanes constituted the largest percentage (>35%) in the mixing ratios of quantified VOCs at the industrial and residential sites, followed by oxy-organics and alkenes (15–25%).The values of aromatics and halohydrocarbons were less than 15%. By contrast, the highest values of oxy-organics accounted for more than 30%. The model of positive matrix factorization was applied to identify the VOC sources and quantify the relative contributions of various sources. Gasoline-related emission (the combination of gasoline exhaust and gas vapor) was the most important VOC-source in the industrial and residential areas, with a relative contribution of 32.1% and 40.4%, respectively. Industrial process was the second most important source with a relative contribution ranging from 30.0% to 40.7%. The relative contribution of solvent usage was 6.5–22.3%. Meanwhile, the relative contribution of biogenic emission was only within the range of 2.0–5.0%. These findings implied the importance of controlling gasoline-related and industrial VOC emissions in reducing the VOC emissions in Wuhan.

Environmental and Health Impacts of the Change in NMHCs Caused by the Usage of Clean Alternative Fuels for Vehicles

ABSTRACT Vehicle exhaust and roadside air samples were collected at Guangzhou, Shenzhen and Chengdu in China, where liquefied petroleum gas (LPG), liquefied natural gas (LNG) and compressed natural gas (CNG)—common fuel alternatives for vehicles worldwide—are used, respectively. The emission characteristics, ozone formation potential (OFP) and health risks of nonmethane hydrocarbons (NMHCs) in conventional and clean alternative fuel exhaust emitted by vehicles were assessed to explore the environmental and health effects from the change in NMHCs due to using clean alternative fuels. Our results indicate that the fuel type significantly impacted the composition of the roadside air. The OFP values for the total NMHCs were much lower in the CNG (2.5 ppmv), LNG (4.7 ppmv) and diesel (4.5 ppmv) exhaust than in the gasoline (94.3 ppmv) and LPG (23.1 ppmv) exhaust, indicating that using CNG and LNG may effectively reduce O3 formation due to vehicle exhaust. Additionally, the hazard quotient (HQ), hazard index (HI) and cancer risk (Risk) of NMHC species in the vehicle exhaust were calculated. Both the HI and Risk of these species in the exhaust from gasoline-powered vehicles greatly exceeded those from the other four types of vehicles, suggesting that using clean alternative fuels instead of gasoline benefits human health.

Evaluation, source apportionment and health risk assessment of heavy metal and polycyclic aromatic hydrocarbons in soil and vegetable of Ahvaz metropolis

Macronutrients, heavy metals, and polycyclic aromatic hydrocarbons (PAHs) were investigated in agricultural soils and vegetables of Ahvaz metropolis to assess the contamination, potential sources, bioconcentration, and related health risks for local residents. For this purpose, 105 and 26 vegetable and soil samples from different parts of the study area were collected and analyzed. The determination of PAHs was carried out using gas chromatography–mass spectrometry and concentrations of elements were measured using ICP-MS methods. Calculated enrichment factor, contamination factor and ecological risk of metals showed that agricultural soil is moderately polluted with regard to Cd and P. The results of positive matrix factorization (PMF) and principal component analysis (PCA) (PCA) demonstrated that Cd, K, and P probably result from anthropogenic sources. One-way ANOVA indicated that heavy metal concentration in different vegetables varied significantly at p ≤ .05. BCF analysis indicated that most analyzed vegetables act as accumulators for K, P, and Mo. The results of PCA (PCA) and concentration ratios of various PAHs demonstrated that high molecular weight (HMW) PAHs in soil is mainly from gasoline and diesel exhaust combustion while, low molecular weight (LMW) PAHs are mostly originated from petrogenic source. Measured soil organic matter and clay content significantly correlate with high molecular weight PAHs concentration. The common practice of using kerosene as an herbicide on parsley and dill farms in Ahvaz area seems to be the major source of low molecular weight PAHs in vegetable samples. Calculated bioconcentration factors indicated that all investigated vegetables are accumulators of Nap, Flu, Phe, BaA, and Chr. Furthermore, calculated human risk indices indicated that local population is potentially exposed to high cancer risk through consumption of PAH contaminated vegetables.

Application of various cytotoxic endpoints for the toxicity prioritization of fine dust (PM2.5) sources using a multi-criteria decision-making approach.

Fine dust (PM2.5) is generated from various sources, and many studies have reported on the sources of PM2.5. However, the current research on PM2.5 toxicity based on its sources is insufficient. In this study, we developed a framework for the prioritization of fine dust (PM2.5) sources on the basis of the multi-endpoint toxicities using the multi-criteria decision-making method (MCDM). To obtain the multi-endpoint toxicities of PM2.5 sources, cell mortality, reactive oxygen species (ROS), inflammation and mutagenicity were measured for diesel exhaust particles (DEP), gasoline exhaust particles (GEP), rice straw burning particles (RBP), coal combustion particles (CCP) and tunnel dust particles (TDP). The integrative toxicity score (ITS) of the PM2.5 source was calculated using MCDM, which consist of four steps: (1) defining the decision-making matrix, (2) normalization and weighting, (3) calculating the ITS (linear aggregation) and (4) a global sensitivity analysis. The indicator of cell mortality had the highest weight (0.3780) followed by inflammation (0.2471), ROS (0.2178) and mutagenicity (0.1571). Additionally, the ITS based on the sources contributing to PM2.5 resulted in the following order: DEP (0.89), GEP (0.44), RBP (0.40), CCP (0.23) and TDP (0.06). The relative toxicity index (RTI), which represents the ratio of toxicity due to the difference in sources, increases as the contribution of the highly toxic sources increases. The RTI over 1 is closely associated with an increased contribution from highly toxic sources, such as diesel exhaust, gasoline exhaust and biomass burning. It is necessary to investigate the toxicity of various PM2.5 sources and PM2.5 risk based on the sources.

The Effect of Fossil Fuel Exhaust on the Germination and Growth of Annual Ryegrass (Lolium multiflorum)

Fossil fuel exhaust contains CO, CO2, SO2, NO, in addition to particulates (soot). It was hypothesized that ryegrass seeds (Lolium multiflorum) when exposed to diesel fuel exhaust would have fewer seeds germinate and sprout. Exhaust collector pans were created and one hundred ryegrass seeds and water were added to each pan. Fossil fuel exhaust was added to two exhaust collector pans. A third pan with no exhaust was prepared. The three pans were placed in a greenhouse for eight days. The seed growth from each pan was calculated and recorded. The mean growth for the control was 100%. The growth for the gasoline exhaust was 85%. The germination for the diesel was 67% and was 19% for sprouting. The t-test analysis of the data had a p-value of 0.0001. The hypothesis was supported because the fossil fuel exhaust did affect the growth of L. multiflorum.

Simulation of effect of bed temperature over producer gas composition using ASPEN PLUS, its experimental validation and emission characteristics of an IC engine

Biomass is the source of energy that is generated from organic materials, which has the capacity to generate power in different means. Gasification is the technique that converts biomass materials into combustible gas by undergoing chemical reactions at high temperature with a controlled oxygen availability. The objective of this study is to determine the performance of downdraft gasifier and emission characteristics of IC engine using producer gases at various bed temperatures. The satisfactory performance of gasification, is theoretically attaining at a gasification temperature range of 500°c to 750°c. The temperature dependency of gasification process in the performance of downdraft gasifier is studied for different types of feed stocks. The downdraft gasifier is simulated using process simulation software ASPEN PLUS. PLUS. It is found that at higher gasification temperatures the quality of producer gas increases considerably. The exhaust emission characteristics and efficiencies of engine with producer gas are comparable with normal gasoline exhaust characteristics.

Analysis of the Emission Conversion Performance of Gasoline Particulate Filters Over Lifetime

<div class="section abstract"><div class="htmlview paragraph">Gasoline particulate filters (GPF) recently entered the market, and are already regarded a state-of-the-art solution for gasoline exhaust aftertreatment systems to enable EU6d-TEMP fulfilment and beyond. Especially for coated GPF applications, the prognosis of the emission conversion performance over lifetime poses an ambitious challenge, which significantly influences future catalyst diagnosis calibrations. The paper presents key-findings for the different GPF application variants. In the first part, experimental GPF ash loading results are presented. Ash accumulates as thin wall layers and short plugs, but does not penetrate into the wall. However, it suppresses deep bed filtration of soot, initially decreasing the soot-loaded backpressure. For the emission calibration, the non-linear backpressure development complicates the soot load monitoring, eventually leading to compromises between high safety against soot overloading and a low number of active regenerations. In the second part, a relevant share of ash deposits inside three-way catalysts (TWC) is depicted. In an experiment, the oxygen storage capacity (OSC) of a three-way catalyst was significantly lowered by ash, while a coated GPF showed little effects. A subsequent OSC regeneration of the TWC showed that the OSC drop is not necessarily permanent, reducing the selectivity between full useful life and borderline catalysts.</div></div>

Sources-specific carcinogenicity and mutagenicity of PM2.5-bound PAHs in Beijing, China: Variations of contributions under diverse anthropogenic activities

To study source-specific carcinogenicity and mutagenicity of polycyclic aromatic hydrocarbons (PAHs) under diverse anthropogenic activities, PM2.5-bound PAHs were detected in Beijing in four periods. PAHs in Asia-Pacific Economic Cooperation meeting (APEC) was much lower than that in after-APEC period. The highest PAHs concentration was in heating period (303 ng/m3). Sources were quantified by Positive Matrix Factorization (PMF). In heating period, due to high emissions, weak diffusion, low degradation and evaporation, high contributions of all sources were observed, and both absolute and relative contributions of coal combustion increased. Changed contributions in during-APEC and after-APEC periods implied effectiveness of reinforced emission control, especially for coal combustion and vehicles. Furthermore, variations of sources-specific carcinogenicity and mutagenicity were investigated. In non-heating period, contributions of gasoline exhaust (38.4% TEQ: Toxic Equivalent Quantity, 33.7% MEQ: Mutagenic Equivalent Quantity) and diesel exhaust (53.8% TEQ, 57.9% MEQ) dominated both carcinogenic and mutagenic risks. Coal combustion sharply increased in heating period, attributing 27.5% TEQ and 21.7% MEQ. In during-APEC period, all contributions to carcinogenicity and mutagenicity were lower than those in after-APEC period, but “others” linked with regional transport contributed increased fractions (above 20%). Sources-specific carcinogenicity and mutagenicity under diverse anthropogenic activities, especially for APEC meeting with reinforced control, gave a new insight into assessment of control measures based on health risks.

The effect of successful low-dose immunotherapy ascertained by provocation neutralization on lymphocytic calcium ion influx following electric field exposure.

Background Low-dose immunotherapy affects baseline levels of intracellular calcium. However, the effect of background electric fields is yet to be ascertained. The aim of this study was to test the following hypotheses: desensitization by low-dose immunotherapy is associated with reduced calcium ion influx during electric field exposure; the effect of low-dose immunotherapy on intracellular calcium ion concentration does not depend on electric field exposure; and the intracellular calcium ion concentration is amplified by electric field exposure. Methods The experimental design was balanced and orthogonal. Intracellular lymphocytic calcium ion concentrations were assayed in 47 patients, following incubation with picogram amounts of 12 test allergens, using a cell-permeable calcium-sensing ratiometric fluorescent dye and fluorescence spectroscopy, both at baseline and following successful provocation neutralization treatment with low-dose immunotherapy. Duplicates were also exposed to an electric field which replicated the frequency spectrum measured in a non-Faraday shielded room. Results A significant or trend-level main effect was found for low-dose immunotherapy for: benzoate; formaldehyde; metabisulfite; natural gas; nitrosamines; organophosphates; salicylate; azo-dyes and precursors; nickel; and petrol (gasoline) exhaust. Significant or trend-level main effects for electric field exposure were observed for: formaldehyde; mercury (inorganic); natural gas; nickel; nitrosamines; petrol exhaust; salicylate; benzoate; and metabisulfite. There was no evidence of a statistical interaction between these two factors. Electric field exposure was associated with a higher intracellular calcium ion concentration. Conclusion There was support for all three hypotheses. The results suggest that patients may experience increased sensitivity to allergens as a result of exposure to everyday electric fields.

Vulnerability of small-scale fishers to benzene exposure and the current knowledge gap on benzene-exposure in Brazilian fishers.

Fishers are a particularly vulnerable population, chronically exposed to many stresses, injuries and health conditions directly linked to their fishing activities. This includes benzene exposure through gasoline and diesel exhaust fumes. Benzene is a known carcinogen, and has been assessed in many worker groups, but reports on fisher benzene exposure are extremely scarce in the literature. This paper discusses benzene exposure in small-scale fishers and reflects on the current knowledge gap on benzene-exposure in Brazilian fishers.

Characteristics and health effects of PM2.5 emissions from various sources in Gwangju, South Korea

Increasing evidence suggests that the toxicity of fine dust particles (PM2.5) is linked to specific components rather than their mass. However, research on the chemical composition and health risk of PM2.5 is insufficient. This study analyzed the metals, polycyclic aromatic hydrocarbon (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) present in PM2.5 and evaluated their risk to health during outdoor activities. The concentration of metals was one order of magnitude higher than that of PAHs and the concentration and detection frequency of OCPs and PCBs were considerably lower than those of metals and PAHs. The lifetime excess cancer risk (LECR) for carcinogens in PM2.5 exceeded de minimis risk (1 × 10−6) as 1.33–3.44 × 10−6 (at 5th–95th percentile) as Cr(VI), As, and Cd showed high contributions. Children in the 2 < years <18 age group had a high risk of cancer due to early-life susceptibility. The proportion of ∑Metals to LECR was approximately 95%, while ∑PAHs attributed to 5% of total LECR. The effects of ∑OCPs and 2,3′,4,4′,5′-Pentachlorobiphenyl (PCB-123) on LECR were negligible. The hazard quotient (HQ) for non-carcinogens was <1, and non-carcinogenic effects were not expected. Mn, BaP, Pb, As, and Cd were the key determinants of the HQ values and among the identified PM2.5 sources they are closely related to industrial activities, oil combustion, and gasoline exhaust. Therefore, control strategies for these sources can effectively reduce PM2.5 risk. This study measured the concentrations of toxic compounds in ambient PM2.5 and considered only PM2.5 exposure during outdoor activities. PM2.5 health risk during the entire day would be higher than the PM2.5 risk determined in this study, and further research is required for this evaluating this risk.

Design of a Novel Gasoline Particulate Filter Aging Method

Gasoline particulate filters (GPF) recently entered the market and are already regarded as state-of-the-art for gasoline exhaust aftertreatment systems to enable EU6d-TEMP fulfillment and beyond. Due to its rapid market introduction, the field of GPF lifetime evaluation is still open for research. In this context, the paper describes the advantages of a method for accelerated investigation of filter ash loading during the development of particulate filters. The central task is the simulation of real-world lubrication oil consumption and combustion, which is the major source of ash in the exhaust gases. For that purpose, a burner test bench designed for catalyst aging was additionally equipped with an oil injection unit. The injection unit enables control of the oil volume and the droplet sizes as precursors for the ash particulates. The results obtained with the new filter aging method are compared with data from vehicle endurance runs and with burner test investigations in which the fuel is doped with oil. The latter method is currently considered as the state-of-the-art method for accelerated ash generation. The new method proofed to be vehicle-equivalent in terms of ash-induced backpressure, filtration efficiency, wall ash layer formation, and wall/plug ash ratio. In this context, it turned out that it is important not to atomize the oil droplets too far, since smallest particulates accumulate mainly at the walls and cause unrealistically high backpressures. Furthermore, the ash loading process should include different mass flows in order to achieve stable backpressure results.

Spatial variation of sources and photochemistry of formaldehyde in Wuhan, Central China

In August 2016, ambient formaldehyde (HCHO) and related parameters were measured simultaneously at a suburban site (Wujiashan, WJS), an urban site (Ziyang, ZY) and a roadside site (Hankou, HK) in Wuhan, Central China. The mixing ratios of HCHO at WJS (2.1 ± 0.2 ppbv) were comparable (p > 0.05) to those at ZY (2.2 ± 0.4 ppbv) and lower (p < 0.01) than those at HK (3.4 ± 0.5 ppbv). Secondary formation made the greatest contributions to ambient HCHO at WJS (61.9 ± 5.9%) and ZY (69.3 ± 7.3%), while vehicle exhaust (i.e., diesel and CNG exhaust, gasoline exhaust) (47.2 ± 10.4%) was the dominant HCHO source at HK. Vehicle exhaust was also the dominant primary source of HCHO at WJS and ZY, accounting for 16.0 ± 4.0%, and 21.9 ± 8.0%, respectively. Biogenic emissions made a non-negligible contribution at suburban site WJS (9.8 ± 3.2%). The precursors of the secondary HCHO were investigated using a photochemical box model. Alkenes and aromatics were found to be the most important contributors to secondary HCHO. The impact of observed HCHO on the production of hydroperoxy radical (HO2) and ozone (O3) were also assessed. The photochemical reactions of HCHO (i.e., the photolysis and OH-initiated oxidation of HCHO) accounted for 10.5 ± 0.6%, 10.6 ± 0.8% and 14.8 ± 0.9% to the formation of HO2 at WJS, ZY and HK, respectively, and reducing HCHO led to a considerable decrease in O3 formation. This study demonstrates the important roles of vehicle exhaust and secondary formation in the sources of HCHO, which have significant photochemical relevance. Attention should be paid to HCHO to control the photochemical pollution in Wuhan effectively.