scholarly journals Comparative Study on the Effects of Ethanol Proportion on the Particle Numbers Emissions in a Combined Injection Engine

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1788
Author(s):  
Ping Sun ◽  
Ze Liu ◽  
Wei Dong ◽  
Song Yang
Keyword(s):  
High Speed ◽  
Engine Speed ◽  
Particle Number ◽  
Direct Injection ◽  
Injection Timing ◽  
Ignition Timing ◽  
Particle Emissions ◽  
Total Particle Number ◽  
Low Load ◽  
Total Particle

Ethanol has significant potential for the reduction of fuel consumption and the emissions of engines. In this paper, a dual-fuel combined engine test rig with ethanol injected in the intake port and gasoline injected directly into the cylinder are developed and the effects of ethanol/gasoline ratio (Re) on the combustion and emission of particle numbers are investigated experimentally. The results indicate that the peak in-cylinder temperature (Tmax) decreases continuously with the increase of the ethanol/gasoline ratio (Re). For particle emissions, ethanol can significantly reduce the accumulation mode particle number (APN) at low engine speed; and the lowest number of particulates are at G25 (the gasoline ratio is 25% of the fuel) at low load. And at high engine load, the total particle number (TPN) is insensitive to speed with large ethanol fraction and TPN is relatively small. With the decrease of Re (Re < 50%), TPN rises sharply. When the direct injection timing advances, TPN reduces continuously and the effects caused by speed can be neglected. On the contrary, the speed has significant effects on particle emissions at various ignition times. At low speed, increasing ignition advance can cause the increase of the TPN; which is contrary to the effects of particle emissions at medium engine speed. And the effect of ignition timing at high speed on particle number is not obvious. The ignition timing for which the lowest TPN is reached will increase with the direct injection timing advances.

On the Premixed Combustion in a Direct-Injection Diesel Engine

1987 ◽  
Vol 109 (2) ◽  
pp. 187-192 ◽  
Author(s):  
A. C. Alkidas
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Engine Speed ◽  
Direct Injection ◽  
Premixed Combustion ◽  
Injection Timing ◽  
Oxides Of Nitrogen ◽  
Nitrogen Emissions ◽  
Direct Injection Diesel Engine ◽  
Diffusion Burning

The factors influencing premixed burning and the importance of premixed burning on the exhaust emissions from a small high-speed direct-injection diesel engine were investigated. The characteristics of premixed and diffusion burning were examined using a single-zone heat-release analysis. The mass of fuel burned in premixed combustion was found to be linearly related to the product of engine speed and ignition-delay time and to be essentially independent of the total amount of fuel injected. Accordingly, the premixed-burned fraction increased with increasing engine speed, with decreasing fuel-air ratio and with retarding injection timing. The hydrocarbon emissions did not correlate well with the premixed-burned fraction. In contrast, the oxides of nitrogen emissions were found to increase with decreasing premixed-burned fraction, indicating that diffusion burning, and not premixed burning, is the primary source of oxides of nitrogen emissions.

scholarly journals Characteristics of sub-10 nm particle emissions from in-use commercial aircraft observed at Narita International Airport

2020 ◽  
Author(s):  
Nobuyuki Takegawa ◽  
Yoshiko Murashima ◽  
Akihiro Fushimi ◽  
Kentaro Misawa ◽  
Yuji Fujitani ◽  
...  
Keyword(s):  
Human Health ◽  
Real World ◽  
Particle Number ◽  
Civil Aviation ◽  
Particle Emissions ◽  
International Airport ◽  
Total Particle Number ◽  
Exhaust Plumes ◽  
Total Particle ◽  
Volatile Particle

Abstract. Civil aviation is undergoing rapid growth as a result of global economic development. Characterizing ultrafine particle emissions from jet aircraft equipped with turbofan engines, which are commonly used in civil aviation, is an important issue for the assessment of the impacts of aviation on climate and on human health. Previous studies have reported that particle number emissions from jet aircraft are dominated by volatile particles (mainly sulphate and organics) with mode diameters of 10–20 nm and that non-volatile particles (mainly soot) exhibit mode diameters of ~20–60 nm, depending on the engine types and thrust conditions. However, there are significant uncertainties in measuring particles with diameters smaller than ~10 nm, especially when fresh aircraft exhaust plumes are measured near the emission sources. We conducted field observations of aerosols and carbon dioxide (CO2) near a runway of Narita International Airport, Japan, in February 2018, with specific focuses on the contributions of sub-10 nm size ranges to total and non-volatile particles. Spiked increases in particle number concentrations and CO2 were observed to be associated with wind directions from the runway, which can be attributed to diluted aircraft exhaust plumes. We estimated the particle number emission indices (EIs) for discrete take-off plumes. The median total particle number EI with diameters larger than 2.5 nm was ~60 times greater than the median non-volatile particle number EI with diameters larger than 10 nm for take-off plumes. This value can be interpreted as the difference between total particle number emissions under real-world conditions and non-volatile particle number emissions regulated by standard engine tests. More than half of particle numbers in the plumes were found in the size range smaller than ~10 nm on average for both total and non-volatile particles. The mode diameters of the size distributions of particle number EIs were found to be smaller than ~10 nm in most cases, and the peak EI values were larger than those previously reported under real-world operating conditions. This study provides new insights into the significance of sub-10 nm particles in aircraft exhaust plumes under real-world conditions, which is important in understanding aviation impacts on human health and also in developing aviation emission inventories for regional and global models.

Gasoline and E85 Combustion Visualization and Particulate Matter Emission in a Production SIDI Engine With Optical Access

2013 ◽  
Author(s):  
Po-I Lee ◽  
Xiaoce Feng ◽  
Ming-Chia Lai
Keyword(s):  
Diffusion Flame ◽  
High Speed ◽  
Particle Number ◽  
Total Concentration ◽  
Direct Injection ◽  
Cylinder Liner ◽  
Operating Conditions ◽  
Coolant Temperature ◽  
Injection Timing ◽  
Optical Access

The present study analyzes the relationship of diffusion flame and PM emission of pure gasoline (E0) and E85 in a spark-ignited direct injection engine at low coolant temperature with optical access on one side of combustion chamber for high speed visualization. Different operating conditions including injection timing, ignition timing, and air-fuel ratio (lambda) with two throttle positions (high and low load) are experimented with a high speed FTIR and an Engine Exhaust Particle Sizer (EEPS) to measure the engine-out emissions. The results show that fuel types and injection timing strongly impact particle size distribution, total concentration, and total mass of PM emission due to piston or cylinder liner wall-wetting. It is concluded that both E0 and E85 present diffusion flame with early injection timing, and the existence of diffusion flame seen in the images corresponds to higher particle mass; however, it does not necessarily represent higher particle number, which is also fuel dependent. In certain conditions, PM emission of E85 could be higher in terms of particle number.

Effect of the valve timing and the coolant temperature on particulate emissions from a gasoline direct-injection engine fuelled with gasoline and with a gasoline–ethanol blend

2012 ◽  
Vol 226 (10) ◽  
pp. 1419-1430 ◽  
Author(s):  
Longfei Chen ◽  
Richard Stone ◽  
Dave Richardson
Keyword(s):  
Particulate Matter ◽  
Particle Number ◽  
Direct Injection ◽  
Coolant Temperature ◽  
Exhaust Gas ◽  
Valve Timing ◽  
Total Particle Number ◽  
Particulate Matter Emissions ◽  
Total Particle ◽  
Gas Recirculation

Variable-valve-timing technology and ethanol addition to gasoline are both considered to be effective strategies for better performance and potential improvement in the fuel economy in gasoline engines. In this study, a Jaguar V8, naturally aspirated spray-guided direct-injection engine was operated with four different valve-timing combinations using an unleaded gasoline and a gasoline–10 vol % ethanol blend. The internal exhaust gas recirculation rate and the in-cylinder gas temperature were modelled for different valve-timing strategies. The results showed that a high valve overlap led to high internal exhaust gas recirculation and a high charge temperature, which evidently improved the fuel spray atomization and reduced the particulate matter emissions. Adding 10 vol % ethanol led to a rise in the total particle number and the total particle mass in emissions by a factor of up to 2 under warm-engine conditions (with a coolant temperature of 90 °C) but led to a reduction in the total particle number and the total particle mass in emissions by up to two-thirds under cold conditions (with a coolant temperature of 20 °C). Thermogravimetric analysis tests were conducted to analyse the compositions of filter-borne particulate matter emissions, and more than 75 mass % organic material was always present. All measurements are reported for both pre- and post-three-way-catalyst samples, the latter always showing a significant reduction (a factor of about 2) in the particulate matter emissions.

scholarly journals Impact of the Coronavirus Pandemic Lockdown on Atmospheric Nanoparticle Concentrations in Two Sites of Southern Italy

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 352
Author(s):  
Adelaide Dinoi ◽  
Daniel Gulli ◽  
Ivano Ammoscato ◽  
Claudia R. Calidonna ◽  
Daniele Contini
Keyword(s):  
Particle Number ◽  
Southern Italy ◽  
Time Intervals ◽  
Atmospheric Particle ◽  
Total Particle Number ◽  
Total Particle ◽  
Consequent Reduction ◽  
Containment Measures ◽  
Coronavirus Infection ◽  
The Impact

During the new coronavirus infection outbreak, the application of strict containment measures entailed a decrease in most human activities, with the consequent reduction of anthropogenic emissions into the atmosphere. In this study, the impact of lockdown on atmospheric particle number concentrations and size distributions is investigated in two different sites of Southern Italy: Lecce and Lamezia Terme, regional stations of the GAW/ACTRIS networks. The effects of restrictions are quantified by comparing submicron particle concentrations, in the size range from 10 nm to 800 nm, measured during the lockdown period and in the same period of previous years, from 2015 to 2019, considering three time intervals: prelockdown, lockdown and postlockdown. Different percentage reductions in total particle number concentrations are observed, −19% and −23% in Lecce and −7% and −4% in Lamezia Terme during lockdown and postlockdown, respectively, with several variations in each subclass of particles. From the comparison, no significant variations of meteorological factors are observed except a reduction of rainfall in 2020, which might explain the higher levels of particle concentrations measured during prelockdown at both stations. In general, the results demonstrate an improvement of air quality, more conspicuous in Lecce than in Lamezia Terme, during the lockdown, with a differed reduction in the concentration of submicronic particles that depends on the different types of sources, their distance from observational sites and local meteorology.

CFD Modelling of the Effects of Injection Timing on the Combustion Process and Emissions in an HSDI Diesel Engine

2012 ◽  
Author(s):  
Raouf Mobasheri ◽  
Zhijun Peng
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Cfd Simulation ◽  
Direct Injection ◽  
Combustion Process ◽  
Injection Timing ◽  
Cfd Modelling ◽  
Combustion Modeling ◽  
Pressure Trace ◽  
Hsdi Diesel Engine

High-Speed Direct Injection (HSDI) diesel engines are increasingly used in automotive applications due to superior fuel economy. An advanced CFD simulation has been carried out to analyze the effect of injection timing on combustion process and emission characteristics in a four valves 2.0L Ford diesel engine. The calculation was performed from intake valve closing (IVC) to exhaust valve opening (EVO) at constant speed of 1600 rpm. Since the work was concentrated on the spray injection, mixture formation and combustion process, only a 60° sector mesh was employed for the calculations. For combustion modeling, an improved version of the Coherent Flame Model (ECFM-3Z) has been applied accompanied with advanced models for emission modeling. The results of simulation were compared against experimental data. Good agreement of calculated and measured in-cylinder pressure trace and pollutant formation trends were observed for all investigated operating points. In addition, the results showed that the current CFD model can be applied as a beneficial tool for analyzing the parameters of the diesel combustion under HSDI operating condition.

scholarly journals Vertical marine snow distribution in the stratified, hypersaline, and anoxic Orca Basin (Gulf of Mexico)

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Arne Diercks ◽  
Kai Ziervogel ◽  
Ryan Sibert ◽  
Samantha B. Joye ◽  
Vernon Asper ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Gulf Of Mexico ◽  
Particle Number ◽  
Sea Surface ◽  
Marine Snow ◽  
Particle Volume ◽  
Total Particle Number ◽  
Total Particle ◽  
Snow Distribution ◽  
Orca Basin

We present a complete description of the depth distribution of marine snow in Orca Basin (Gulf of Mexico), from sea surface through the pycnocline to within 10 m of the seafloor. Orca Basin is an intriguing location for studying marine snow because of its unique geological and hydrographic setting: the deepest ~200 m of the basin are filled with anoxic hypersaline brine. A typical deep ocean profile of marine snow distribution was observed from the sea surface to the pycnocline, namely a surface maximum in total particle number and midwater minimum. However, instead of a nepheloid (particle-rich) layer positioned near the seabed, the nepheloid layer in the Orca Basin was positioned atop the brine. Within the brine, the total particle volume increased by a factor of 2–3 while the total particle number decreased, indicating accumulation and aggregation of material in the brine. From these observations we infer increased residence time and retention of material within the brine, which agrees well with laboratory results showing a 2.2–3.5-fold reduction in settling speed of laboratory-generated marine snow below the seawater-brine interface. Similarly, dissolved organic carbon concentration in the brine correlated positively with measured colored dissolved organic matter (r2 = 0.92, n = 15), with both variables following total particle volume inversely through the pycnocline. These data indicate the release of dissolved organic carbon concomitant with loss in total particle volume and increase in particle numbers at the brine-seawater interface, highlighting the importance of the Orca Basin as a carbon sink.

scholarly journals Urban aerosol size distributions over the Mediterranean city of Barcelona, NE Spain

2012 ◽  
Vol 12 (7) ◽  
pp. 16457-16492 ◽  
Author(s):  
M. Dall'Osto ◽  
D.C.S. Beddows ◽  
J. Pey ◽  
S. Rodriguez ◽  
A. Alastuey ◽  
...  
Keyword(s):  
Particle Number ◽  
Number Concentration ◽  
Aerosol Size Distribution ◽  
Time Variability ◽  
Small Contribution ◽  
Particle Number Concentration ◽  
Size Distributions ◽  
Total Particle Number ◽  
Total Particle ◽  
One Year

Abstract. Differential mobility particle sizer (DMPS) aerosol concentrations (N13–800) were collected over a one-year-period (2004) at an urban background site in Barcelona, North-Eastern Spain. Quantitative contributions to particle number concentrations of the nucleation (33–38%), Aitken (39–49%) and accumulation mode (18–22%) were estimated. We examined the source and time variability of atmospheric aerosol particles by using both K-means clustering and Positive Matrix Factorization (PMF) analysis. Performing clustering analysis on hourly size distributions, nine K-means DMPS clusters were identified and, by directional association, diurnal variation and relationship to meteorological and pollution variables, four typical aerosol size distribution scenarios were identified: traffic (69% of the time), dilution (15% of the time), summer background conditions (4% of the time) and regional pollution (12% of the time). According to the results of PMF, vehicle exhausts are estimated to contribute at least to 62–66% of the total particle number concentration, with a slightly higher proportion distributed towards the nucleation mode (34%) relative to the Aitken mode (28–32%). Photochemically induced nucleation particles make only a small contribution to the total particle number concentration (2–3% of the total), although only particles larger than 13 nm were considered in this study. Overall the combination of the two statistical methods is successful at separating components and quantifying relative contributions to the particle number population.

Multi-point micro-flame ignited hybrid lean-burn combustion of gasoline with direct injection dimethyl ether

2019 ◽  
Vol 22 (1) ◽  
pp. 140-151 ◽  
Author(s):  
Xue-Qing Fu ◽  
Bang-Quan He ◽  
Si-Peng Xu ◽  
Tao Chen ◽  
Hua Zhao ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
Heat Release ◽  
Dimethyl Ether ◽  
Direct Injection ◽  
Injection Timing ◽  
Ignition Timing ◽  
Double Peak ◽  
Lean Burn ◽  
Combustion Duration ◽  
Low Nitrogen

Lean-burn combustion is effective in reducing fuel consumption of gasoline engines because of the higher specific heat ratio of the fuel lean mixture and reduced heat loss from lower combustion temperature. However, its application to real engines is hampered by the unstable ignition, high cyclic variability, and partial-burn due to slower combustion, as well as the restricted maximum lean-burn air/fuel ratio limit and the insufficiently low nitrogen oxides emission. Multi-point micro-flame-ignited hybrid combustion has been proposed and applied to extend the lean burn limit of premixed gasoline and air mixture. To achieve micro-flame-ignited combustion in premixed lean gasoline mixture formed by port fuel injection, a small amount of dimethyl ether is injected directly into the cylinder of a four-stroke gasoline engine to control and accelerate the ignition and combustion process so that the engine could be operated with the overall excess air coefficient (Lambda) of 1.9. The results show that heat release processes can be grouped into three forms, that is, ramp type, double-peak type, and trapezoid type. Regardless of single or split injections, direct injection timing of dimethyl ether dominates the features of heat release. The ramp type occurs at early injection timing while the double-peak type takes place at late injection timing. Trapezoid type appears between the above two types. Dimethyl ether injection timing controls the ignition timing and has less effect on combustion duration. Single injection of dimethyl ether leads to much earlier ignition timing and slightly longer combustion duration, forming higher nitrogen oxides emissions than the split injections. Ultra-low nitrogen oxides emissions and higher thermal efficiency are achieved in the ramp type combustion compared to the other two types of combustion in both injection approaches.

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