Gasoline Engine Emissions Research Articles

PENGARUH SUHU BAHAN BAKAR TERHADAP EMISI GAS BUANG PADA MESIN BENSIN 1800 cc


 
 
 The perfect combustion process can occur if the high compression pressure, proper ignition time, and suitable fuel air mixture. Suitable fuel air mixture can be obtained by heating the fuel to reduce its viscosity so the mixture is more homogeneous. Fuel heating can be done in various ways, such as by utilizing the heat of radiator water coming out of the engine. The purpose of the study is determine effect of the fuel heating to exhaust emission of gasoline engine 1800cc. The study uses experimental with the variable used pertamax with temperature 40°, 50°, 60°, and 70°. The dependent variable in the study is exhaust emission of gasoline engine. The results of the study indicate that fuel heating affects exhaust emissions. Temperature that affects the exhaust gas emissions at 60o C with the use of pertamax fuel.
 
 

Effect of Water Injection Timing on the Combustion and Emissions of a Direct Injection Gasoline Engine

Knock is the main limiting factor of performance improvement when downsizing spark ignition (SI) engines. Direct water injection in the cylinder can effectively suppress knock. Moreover, water can absorb the heat generated by combustion and reduce the maximum temperature, which can also reduce NOX emissions. The water injection timing will change the distribution of water in the cylinder and affect the combustion and emissions of the gasoline engine. Herein, the effects of different water injection timings on the combustion and emissions of a direct injection gasoline (GDI) engine are examined with numerical simulation. For the combustion performance, the cumulative heat release in the cylinder at different timings of water injection is about 2900 J. However, the instantaneous heat release rate and the combustion duration are different. Compared with other water injection timings, when the water injection time is −80 °CA, the distribution of water in the cylinder is the most even, the potential for reducing knock is the highest, and the NOX emission is the lowest, but the cycle work is also the least. When the water injection time is −20 °CA, the results are opposite.

Plasma sprayed CuO coatings for gas sensing and catalytic conversion applications

Abstract Plasma spray was used to deposit copper oxide (CuO) coating for gas sensing and catalytic conversion applications. Amongst tin oxide (SnO2), tungsten oxide (WO3) and copper oxide (CuO), CuO showed efficient catalytic conversion. Therefore, CuO was selected to deposit catalyst coating. The gas sensing layer was produced on the alumina plate whereas the catalyst layer was produced on the silica-35 wt. % alumina perforated ceramic disc. Plasma sprayed CuO gas sensor coating showed maximum response % (110) towards 500 ppm carbon monoxide (CO) at 150 °C. This coating was useful to detect CO in a wide concentration range (500−5 ppm). It also demonstrated selective sensing capability towards CO in the presences of NO2 and i- C4H10. Next, CuO coatings were packed inside a fabricated test ring and tested for a catalytic conversion of gasoline engine emissions. CuO catalytic coatings could decrease CO, HC and NOx emissions by almost 80 %. This coating can thus, be used as a sense and shoot device to first detect harmful gases followed by its conversion to benign gases in hazardous environments such as automobile exhaust.

Traffic generated emissions alter the lung microbiota by promoting the expansion of Proteobacteria in C57Bl/6 mice placed on a high-fat diet

Air pollution has been documented to contribute to severe respiratory diseases like asthma and chronic obstructive pulmonary disorder (COPD). Although these diseases demonstrate a shift in the lung microbiota towards Proteobacteria, the effects of traffic generated emissions on lung microbiota profiles have not been well-characterized. Thus, we investigated the hypothesis that exposure to traffic-generated emissions can alter lung microbiota and immune defenses. Since a large population of the Western world consumes a diet rich in fats, we sought to investigate the synergistic effects of mixed vehicle emissions and high-fat diet consumption. We exposed 3-month-old male C57Bl/6 mice placed either on regular chow (LF) or a high-fat (HF: 45% kcal fat) diet to mixed emissions (ME: 30 µg PM/m3 gasoline engine emissions+70 µg PM/m3 diesel engine emissions) or filtered air (FA) for 6 h/d, 7 d/wk for 30 days. Levels of pulmonary immunoglobulins IgA, IgG, and IgM were analyzed by ELISA, and lung microbial profiling was done using qPCR and Illumina 16 S sequencing. We observed a significant decrease in lung IgA in the ME-exposed animals, compared to the FA-exposed animals, both fed a HF diet. Our results also revealed a significant decrease in lung IgG in the ME-exposed animals both on the LF diet and HF diet, in comparison to the FA-exposed animals. We also observed an expansion of Enterobacteriaceae belonging to the Proteobacteria phylum in the ME-exposed groups on the HF diet. Collectively, we show that the combined effects of ME and HF diet result in decreased immune surveillance and lung bacterial dysbiosis, which is of significance in lung diseases.

Development of a mechanism-dynamic-selection turbulent premixed combustion model with application to gasoline engine combustion and emissions simulation

In order to overcome the drawback (tuning reaction rate coefficients) of using a single mechanism in the chemical-kinetics-based turbulent premixed combustion modelling approach, a mechanism-dynamic-selection turbulent premixed combustion model has been developed, validated, and successfully applied to the combustion and emissions simulation of spark ignition gasoline engines. In this new model, based on the local thermal and turbulent conditions of any preheat cell, a certain chemical kinetic mechanism which can achieve the target ratio of turbulent flame speed to laminar flame speed is selected. To realise this goal, based on the laminar flame speed sensitivity analysis of an improved eTRF (ethanol toluene reference fuel) base chemical kinetic mechanism, a derived mechanism library has been generated. Based on enough experimental and DNS (direct numerical simulation) data of S T/S L, a mechanism selection database (mechanism as a function of Borghi-Peters coordinates) has been constructed and implemented into a CFD (computational fluid dynamics) code, also a classification scheme for identifying unburned, preheat, flame front, and burned zones of a combustion domain has been developed and implemented into the CFD code. The developed mechanism-dynamic-selection turbulent premixed combustion model has been validated using the combustion in a spherical constant volume and applied to the prediction of combustion and emissions of a spark ignition gasoline engine under transient cold start process. Validation results show that, without tuning any model parameters, the base mechanism, the derived mechanism library, the mechanism selection function, the classification scheme, as well as a simulation setup strategy for modelling engine transient cold start process, have good prediction performances and are practical for engine combustion and emissions simulation.

Ordinary Gasoline Emissions Induce a Toxic Response in Bronchial Cells Grown at Air-Liquid Interface.

Gasoline engine emissions have been classified as possibly carcinogenic to humans and represent a significant health risk. In this study, we used MucilAir™, a three-dimensional (3D) model of the human airway, and BEAS-2B, cells originating from the human bronchial epithelium, grown at the air-liquid interface to assess the toxicity of ordinary gasoline exhaust produced by a direct injection spark ignition engine. The transepithelial electrical resistance (TEER), production of mucin, and lactate dehydrogenase (LDH) and adenylate kinase (AK) activities were analyzed after one day and five days of exposure. The induction of double-stranded DNA breaks was measured by the detection of histone H2AX phosphorylation. Next-generation sequencing was used to analyze the modulation of expression of the relevant 370 genes. The exposure to gasoline emissions affected the integrity, as well as LDH and AK leakage in the 3D model, particularly after longer exposure periods. Mucin production was mostly decreased with the exception of longer BEAS-2B treatment, for which a significant increase was detected. DNA damage was detected after five days of exposure in the 3D model, but not in BEAS-2B cells. The expression of CYP1A1 and GSTA3 was modulated in MucilAir™ tissues after 5 days of treatment. In BEAS-2B cells, the expression of 39 mRNAs was affected after short exposure, most of them were upregulated. The five days of exposure modulated the expression of 11 genes in this cell line. In conclusion, the ordinary gasoline emissions induced a toxic response in MucilAir™. In BEAS-2B cells, the biological response was less pronounced, mostly limited to gene expression changes.

Exposure to Traffic-Generated Pollutants Exacerbates the Expression of Factors Associated with the Pathophysiology of Alzheimer's Disease in Aged C57BL/6 Wild-Type Mice.

Multiple studies report a strong correlation between traffic-generated air pollution-exposure and detrimental outcomes in the central nervous system (CNS), including Alzheimer's disease (AD). Incidence of AD is rapidly increasing and, worldwide, many live in regions where pollutants exceed regulatory standards. Thus, it is imperative to identify environmental pollutants that contribute to AD, and the mechanisms involved. We investigated the effects of mixed gasoline and diesel engine emissions (MVE) on the expression of factors involved in progression of AD in the hippocampus and cerebrum in a young versus aged mouse model. Young (2 months old) and aged (18 months old) male C57BL/6 mice were exposed to either MVE (300μg/m3 PM) or filtered air (FA) for 6 h/d, 7 d/wk, for 50 d. Immunofluorescence and RT-qPCR were used to quantify oxidative stress (8-OHdG) and expression of amyloid-β protein precursor (AβPP), β secretase (BACE1), amyloid-β (Aβ), aryl hydrocarbon receptor (AhR), cytochrome P450 (CYP) 1B1, angiotensin-converting enzyme (ACE1), and angiotensin II type 1 (AT1) receptor in the cerebrum and hippocampus, in addition to cerebral microvascular tight junction (TJ) protein expression. We observed age-related increases in oxidative stress, AhR, CYP1B1, Aβ, BACE1, and AT1 receptor in the CA1 region of the hippocampus, and elevation of cerebral AβPP, AhR, and CYP1B1 mRNA, associated with decreased cerebral microvascular TJ protein claudin-5. MVE-exposure resulted in further promotion of oxidative stress, and significant increases in AhR, CYP1B1, BACE1, ACE1, and Aβ, compared to the young and aged FA-exposed mice. Such findings suggest that MVE-exposure exacerbates the expression of factors in the CNS associated with AD pathogenesis in aged populations.

Does Exposure to Agricultural Chemicals Increase the Risk of Prostate Cancer among Farmers?

Several studies suggest that farmers may be at increased risk of prostate cancer. The present analysis, based on a large population-based case-control study conducted among men in the Montreal area in the early 1980's, aim at identifying occupational chemicals which may be responsible for such increases. The original study enrolled 449 prostate cancer cases, nearly 4,000 patients with other cancers, as well as 533 population controls. Subjects were interviewed about their occupation histories, and a team of industrial hygienists assigned their past exposures using a checklist of some 300 chemicals. The present analysis was restricted to a study base of men who had worked as farmers earlier in their lives. There were a total of 49 men with prostate cancers, 127 with other cancers and 56 population controls. We created a pool of 183 controls combining the patients with cancers at sites other than the prostate and the population controls. We then estimated the odds ratio for prostate cancer associated with exposure to each of 10 agricultural chemicals, i.e., pesticides, arsenic compounds, acetic acid, gasoline engine emissions, diesel engine emissions, polycyclic aromatic hydrocarbons from petroleum, lubricating oils and greases, alkanes with >or=18 carbons, solvents, and mononuclear aromatic hydrocarbons. Based on a model adjusting for age, ethnicity, education, and respondent status, there was evidence of a two-fold excess risk of prostate cancer among farmers with substantial exposure to pesticides [odds ratio (OR)=2.3, 95% confidence interval (CI) 1.1-5.1], as compared to unexposed farmers. There was some suggestion, based on few subjects, of increased risks among farmers ever exposed to diesel engine emissions (OR=5.7, 95% CI 1.2-26.5). The results for pesticides are particularly noteworthy in the light of findings from previous studies. Suggestions of trends for elevated risks were noted with other agricultural chemicals, but these are largely novel and need further confirmation in larger samples.

Occupational exposures and lung cancer risk - an analysis of the CARTaGENE study

Objective: To investigate the possible associations between selected occupational agents and lung cancer risk. Methods: A case-cohort design was nested within the CARTaGENE study. Cases included all participants with an incident diagnosis of lung cancer occurring during the follow-up from 2009 to 2015 (N=178). For comparison, a sub-cohort of 1033 individuals was established based on a stratified sample of the cohort at baseline. Information on participants’ longest-held job was collected at baseline and coded by an occupational hygienist according to the International Standard Classification of Occupations 1968 (ISCO-68). The job codes were then linked to the Canadian Job Exposure Matrix (CANJEM) to determine the probability of exposure to a list of 258 agents. This analysis was restricted to the 28 most prevalent agents with at least 5 exposed cases. Separate multivariable logistic regression models with robust variance estimators were used to estimate odd ratios (OR) and 95% confidence intervals (95% CI) for the associations between each agent and lung cancer risk while controlling for established lung cancer risk factors, notably smoking. Results: Increased lung cancer risk was found among those exposed to ashes (OR=3.8; 95% CI: 1.5-9.5), hydrogen chloride (OR=4.4; 95% CI: 1.2-16.0), formaldehyde (OR=2.3; 95% CI: 1.3-4.2), cooking fumes (OR=2.4; 95% CI: 1.1-5.3), paints and varnishes used on surfaces other than metal and wood (OR=3.2; 95% CI: 1.0-9.8), alkanes (OR=2.6; 95% CI: 1.2-5.5), aliphatic aldehydes (OR= 2.9; 95% CI: 1.3-4.3), and cleaning agents (OR=1.6; 95% CI: 1.0-2.5). A reduced lung cancer risk was observed among participants exposed to gasoline engine emissions (OR=0.5; 95% CI: 0.2-1.0) and polycyclic aromatic hydrocarbons (PAHs) from petroleum (OR=0.3; 95% CI: 0.1-0.9). Conclusion: Our preliminary findings provide support for the role of several occupational agents, for which we have limited knowledge, in contributing to lung cancer risk.

Comparison of metallic (FeCrAl) and Ceramic Catalytic Converter (CATCO) in reducing exhaust gas emission of gasoline engine fuelled by RON 95 to develop health environment

Environmental and human health problemscaused by high air pollutant which contributed by transportation sector become main issue in the world. There are someair pollutants from gasoline engine such as Carbon Monoxide (CO), Nitrogen Oxide (NOx) and Hydro-Carbon (HC). Therefore, the objective is to investigate the effectiveness of catalytic converter (CATCO) as pollutant converter in reducing harmful exhaust gas and improving the conversion efficiency. The exhaust emission analysis is conducted by gasoline engine model Mitsubishi4G93 in various engine load of 10%, 20% and 30% and various speed of 1000, 2000 and 3000 rpm fuelled by RON 95. The result shows that the ceramic material more effective to reduce the CO and HC as compared to metallic material with maximum conversion is 99.02% at speed of 1000 rpm in engine load of 20% and 97.66% at speed of 1000 rpm and 10%engine load. Meanwhile, Metallic CATCO shows the lower NOx emission as compared to ceramic with the lowest NOx is 128.27 ppm which shown by speed of 1000 rpm and 10%engine load. The lowest emission mostly at speed of 1000 rpm and at lower engine load. It caused by engine load and speed increased as CO, NOx and HC increased as well.

Low-Temperature Ammonia Production during NO Reduction by CO Is Due to Atomically Dispersed Rhodium Active Sites

Rhodium plays a key role in three-way catalysts to control NOx emissions in gasoline engines primarily through the reduction of NO by CO. Despite extensive investigation, there remains uncertainty ...

Environmental impact of industrial transport


 
 
 The article discusses topical issues and problems of the impact of industrial road transport on the environment, namely: emissions of pollutants into the atmosphere depending on the type of fuel and their negative impact on human health. The significant increase in the vehicle fleet is causing great harm in the form of harmful emissions from fuel combustion systems, which cannot be dealt with standard car cleaning systems. The situation is aggravated by the fact that car emissions are concentrated in the surface air layer - precisely in the zone of our breathing. Low- quality gasoline is still used, polluting the environment. About 280 harmful substances were found in the exhaust gases of cars, including carcinogenic benzopyrenes, nitrogen oxides, lead, mercury, aldehydes, carbon oxides, soot, hydrocarbons. These emissions increase significantly when starting off or increasing speed. Diesel engine emissions are different from gasoline engine emissions. A diesel engine burns fuel more completely, oxidizes less carbon and produces less non-combustible hydrocarbons. But, at the same time, due to the lack of air in the diesel engine, more nitrogen oxide is formed. Diesel engines also emit soot. Gas emissions from transport into the atmosphere are exposed to sunlight, which leads to photochemical reactions leading to the formation of NО2, 0з, peroxides, benzopyrene (C22H14) and other compounds. In addition, each vehicle emits rubber dust into the atmosphere when its tires are abraded and worn out. Accordingly, the scale of damage caused by transport to the environment and people is also increasing. The article analyzes the existing and promising types of fuel and the reduction of the technogenic impact of industrial road transport on the environment in Ukraine.
 
 

Effect of water injection on the knock, combustion, and emissions of a direct injection gasoline engine

A turbocharged downsizing spark ignition (SI) engine cooperating with in-cylinder direct injection technology is one of the most effective ways to improve the fuel economy and to reduce the emissions of gasoline engines, but knock combustion limits the application and development of downsizing of SI engines in practice. In this research, a numerical simulation method was used to study the feasibility of in-cylinder direct water injection technology to weaken the knock tendency of a turbocharged direct injection gasoline (GDI) engine and improve its combustion emission performance. First, the knock of a certain type of turbocharged direct injection gasoline engine was induced by increasing the spark timing, thereby determining the position at which the end mixture was spontaneously ignited. Then, at a given water injection moment, the influence of the amount of water injection on the knock and emissions of the turbocharged direct injection gasoline engine was investigated. The results show that the knock intensity gradually decreased with the increase of the water injection quality. For the cyclic work, the amount of circulating work decreased with the increase of the water injection quality. Water injection is beneficial for reducing the emissions of nitrogen oxides (NOX), carbon monoxide (CO), and unburned hydrocarbons (UHC). However, the soot emissions will increase as the amount of water injection increases.

Effect of hydroxy gas addition on performance and exhaust emissions in variable compression spark ignition engine

Due to increase in the usage of fossil fuels and the various engine emissions which are polluting the environment, it is necessary to go for an alternative method to meet the scarcity of fuels and to reduce the emissions. Expert studies indicate the use of hydroxy gas produced using water by electrolysis in petrol/diesel engine can be the solution for the integrated problem of depletion of hydrocarbon fuels and exhaust emissions. This study mainly deals with the outcome of adding hydroxy gas to gasoline on the performance of variable compression gasoline engine and engine emissions. Currently hydroxy gas is generated in a leakage proof Plexiglas generator with potassium hydroxide electrolyte and is attached to a 4-stroke water cooled variable compression gasoline engine. The results from the experimental study conducted on the engine for compression ratios ranging from 7 to 10 shows a decrease in the total fuel consumption and an increase in brake thermal efficiency due to increase in velocity flame propagation assures complete fuel combustion and permits the engine to be operated at lean ranges. Also the exhaust emissions CO2, CO, O2, HC and NOx are measured by hydroxy gas addition to gasoline and without it

Investigation into pressure dependence of flame speed for fuels with low and high octane sensitivity through blending ethanol

Spark assistance for homogeneous charge compression ignition (HCCI) can control combustion phasing, improve thermal efficiency, and reduce emissions in gasoline engines. As the characteristics of flame propagation determine the control authority of ignition timing, it is important and necessary to investigate pressure dependence of flame speed in the lean-premixed mixture relative to engine operating conditions. Experimental study in an optical rapid compression machine (RCM) and simulation work were carried out using two fuels comprising n-heptane/iso-octane/ethanol with varied octane sensitivity (S). The effective pressure ranged from 10 to 35 bar, temperature from 715 to 860 K, and equivalence ratios between 0.3 and 0.7 to cover the region of lean flammability limits of low and high S fuels with ethanol blended. Based on pressure profiles, flame speed extracted from images, and sensitivity analysis of flame speed, the dependence of flame speed on the effective pressure in low and high S fuels was discovered and the fundamental mechanism behind this phenomena became to be understood in the negative temperature coefficient (NTC) and non-NTC regions, respectively. In the studied temperature conditions, the flame speed of high S fuel has stronger dependence on the pressure than that of low S fuel does. In the NTC region, this phenomenon is attributed to the dependence of H radical concentration on pressure in the unburned mixture and flame structure. In the non-NTC region, promoting effect of dominant reactions varied with pressure can significantly influence pressure dependence of flame speed. Although quite limited data of laminar burning velocity for studied fuels were obtained in high pressures (>15 bar), the trend of flame speed's dependence on pressure was well predicted by two models with different but well-accepted core mechanisms, showing consistent results with the experimental ones in the RCM.

The Biological Effects of Complete Gasoline Engine Emissions Exposure in a 3D Human Airway Model (MucilAirTM) and in Human Bronchial Epithelial Cells (BEAS-2B).

The biological effects induced by complete engine emissions in a 3D model of the human airway (MucilAirTM) and in human bronchial epithelial cells (BEAS-2B) grown at the air–liquid interface were compared. The cells were exposed for one or five days to emissions generated by a Euro 5 direct injection spark ignition engine. The general condition of the cells was assessed by the measurement of transepithelial electrical resistance and mucin production. The cytotoxic effects were evaluated by adenylate kinase (AK) and lactate dehydrogenase (LDH) activity. Phosphorylation of histone H2AX was used to detect double-stranded DNA breaks. The expression of the selected 370 relevant genes was analyzed using next-generation sequencing. The exposure had minimal effects on integrity and AK leakage in both cell models. LDH activity and mucin production in BEAS-2B cells significantly increased after longer exposures; DNA breaks were also detected. The exposure affected CYP1A1 and HSPA5 expression in MucilAirTM. There were no effects of this kind observed in BEAS-2B cells; in this system gene expression was rather affected by the time of treatment. The type of cell model was the most important factor modulating gene expression. In summary, the biological effects of complete emissions exposure were weak. In the specific conditions used in this study, the effects observed in BEAS-2B cells were induced by the exposure protocol rather than by emissions and thus this cell line seems to be less suitable for analyses of longer treatment than the 3D model.

Source apportionment of organic pollutants in fine and coarse atmospheric particles in Doha, Qatar

ABSTRACT In this study, we investigated the sources of organic pollutants associated with fine (PM2.5) and coarse (PM2.5–10) atmospheric particulate matter in Doha, Qatar based on an eight-month sampling campaign conducted from May to December 2015. Multiple organic compound tracers including 36 PAH members, 25 n-alkane homologs, 17 hopanes, and 12 steranes were used for organic aerosols source apportionment. Source apportionment based on specific molecular markers, molecular diagnostic ratios/indices, and positive matrix factorization (PMF) modeling showed that similar sources are responsible for both fine- and coarse-particle organic pollutants. PMF analysis showed that biogenic aerosols, fugitive dust emissions, gasoline engine emissions, diesel engine emissions, and heavy oil combustion were the five main pollution sources of organic aerosols, which agreed well with the results from the diagnostic ratios analysis. The conditional bivariate probability functions (CPF) and potential source contribution function (PSCF) indicated that both regional (i.e., mixed biogenic/secondary particles and oil refinery/shipping emissions) and local sources contributed to airborne organic aerosol concentrations observed at the site, depending on the wind speed and direction. It appears that the relatively high levels of organic pollutants were contributed by local anthropogenic sources, such as fossil fuel combustion, vehicular emissions, and fugitive dust emissions. The high levels of local contributions indicated that there might be great opportunities for Qatar to considerably reduce emissions so that population exposures to carbonaceous aerosols and the public health risks associated with air pollution can be minimized. Implications: Multiple organic tracers and various source apportionment techniques have been used for convincing source apportionment. It was found that both long-range and local sources have a significant impact on atmospheric carbonaceous particles in the area, depending on the wind conditions. Relatively high levels of organic pollutants attributed to local anthropogenic sources indicate that there are great opportunities for Qatar to establish and implement more efficient pollution control measures and policies. Regional sources such as petroleum refineries and shipping-vessels emissions in the Gulf region should also be regulated and managed through regional cooperation to improve the air quality in the region.

Comparison of flash boiling resistance of two injector designs and the consequences on downsized gasoline engine emissions

This paper presents a comparative study of two injectors designed for the same Gasoline Turbocharged Direct Injection engine, one featuring 5 holes and one with 6 holes. Hole diameter and circumferential spacing also differed between the two injectors in order to optimise targeting while maintaining flow rate and drop size distribution. By comparing the macroscopic spray characteristics of the two injectors, this study investigated possible design features which may better maintain a spray’s intended morphology under severe flash boiling conditions. The sprays of each injector were firstly investigated by imaging in a quiescent pressure vessel before also being imaged in an endoscopically accessed version of the target 3-cylinder downsized engine to understand the impact of the spray morphology on performance and emissions. Near field images from the pressure vessel indicated that the 5-hole injector could tolerate a greater superheated degree before experiencing spray collapse, maintain its intended morphology better and exhibited a wider plume and shorter penetration length than the 6-hole injector for a given condition. Endoscopic images from the engine indicated that the spray area of the 5-hole injector was always wider under a range of start of injection timings, leading to a better air-fuel mixture and the observation of less diffusive combustion. The PN (particulate) emissions of the 5-hole injector was also consistently lower than the 6-hole injector under different injection timings due to better mixing and less piston impingement, whilst also being less sensitive to changes of injection timing due to its ability to maintain its spray morphology.

Model-Based Analysis of TWC-Coated Filters Performance

The wall flow filter technology is already an important element in gasoline engine emissions control. In addition to the filtration functions, the active catalytic coating can contribute to the reduction of gaseous emissions slipping from the upstream three-way catalytic converters (TWC). The substrate and coating technology require precise engineering to achieve the emission target without sacrificing fuel penalty associated with excessive backpressure and active regeneration. The present contribution addresses the main challenges in developing predictive models supporting the design and control of coated gasoline particulate filters (cGPFs), including filtration and pressure drop, soot oxidation, and effects of ash. The effect of soot and ash on TWC functions as well as the O2 competition between soot and the reactive surface are studied by analyzing the coupled transport–reaction processes at wall scale. The modeling study is supported by measurements with filters of different cell structures and washcoat amounts performed under steady-state and transient modes.

Mixed Vehicle Emissions Induces Angiotensin II and Cerebral Microvascular Angiotensin Receptor Expression in C57Bl/6 Mice and Promotes Alterations in Integrity in a Blood-Brain Barrier Coculture Model.

Exposure to traffic-generated pollution is associated with alterations in blood-brain barrier (BBB) integrity and exacerbation of cerebrovascular disorders. Angiotensin (Ang) II signaling through the Ang II type 1 (AT1) receptor is known to promote BBB disruption. We have previously reported that exposure to a mixture of gasoline and diesel vehicle engine emissions (MVE) mediates alterations in cerebral microvasculature of C57Bl/6 mice, which is exacerbated through consumption of a high-fat (HF) diet. Thus, we investigated the hypothesis that inhalation exposure to MVE results in altered central nervous system microvascular integrity mediated by Ang II-AT1 signaling. Three-month-old male C57Bl/6 mice were placed on an HF or low-fat diet and exposed via inhalation to either filtered air (FA) or MVE (100 μg/m3 PM) 6 h/d for 30 days. Exposure to HF+MVE resulted in a significant increase in plasma Ang II and expression of AT1 in the cerebral microvasculature. Results from a BBB coculture study showed that transendothelial electrical resistance was decreased, associated with reduced expression of claudin-5 and occludin when treated with plasma from MVE+HF animals. These effects were attenuated through pretreatment with the AT1 antagonist, Losartan. Our BBB coculture showed increased levels of astrocyte AT1 and decreased expression of aryl hydrocarbon receptor and glutathione peroxidase-1, associated with increased interleukin-6 and transforming growth factor-β in the astrocyte media, when treated with plasma from MVE-exposed groups. Our results indicate that inhalation exposure to traffic-generated pollutants results in altered BBB integrity, mediated through Ang II-AT1 signaling and inflammation, which is exacerbated by an HF diet.