scholarly journals Influence of Cavitation in Common-Rail Diesel Nozzles on the Soot Formation Process through Measuring Soot Emissions

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6267
Author(s):  
José Javier López ◽  
Oscar A. de la de la Garza ◽  
Joaquín De la De la Morena ◽  
Simón Martínez-Martínez
Keyword(s):  
Formation Process ◽  
Soot Formation ◽  
Soot Oxidation ◽  
Operating Conditions ◽  
Common Rail ◽  
Injection Velocity ◽  
Effective Diameter ◽  
Nozzle Orifice ◽  
Soot Emissions ◽  
Lift Off

The influence of cavitation in common-rail diesel nozzles on the soot formation process has been analysed experimentally. The soot formation process was characterized by measuring soot emissions in a single-cylinder engine, which was mounted on a test bench equipped with an opacimeter. In order to do this, operating conditions where the soot oxidation process was equivalent were chosen, whereby differences in the soot formation process were possible to be analysed. The results achieved confirm that cavitation provokes a soot formation process reduction. This reduction can be attributed by combining results of three effects: a reduction of the effective diameter, an increase in effective injection velocity, and an increase in turbulence level inside the nozzle orifice leading to a longer lift-off length. The three effects lead to a decrease in relative fuel/air ratio at the lift-off, therefore explaining the soot formation reduction.

scholarly journals Possibilities of Simultaneous In-Cylinder Reduction of Soot andNOxEmissions for Diesel Engines with Direct Injection

2008 ◽  
Vol 2008 ◽  
pp. 1-13 ◽  
Author(s):  
U. Wagner ◽  
P. Eckert ◽  
U. Spicher
Keyword(s):  
Nitrogen Oxide ◽  
Diesel Engines ◽  
Fuel Injection ◽  
Soot Formation ◽  
Soot Oxidation ◽  
The Other ◽  
Injection System ◽  
Nitrogen Oxide Emissions ◽  
Injection Strategy ◽  
Soot Emissions

Up to now, diesel engines with direct fuel injection are the propulsion systems with the highest efficiency for mobile applications. Future targets in reducingCO2-emissions with regard to global warming effects can be met with the help of these engines. A major disadvantage of diesel engines is the high soot and nitrogen oxide emissions which cannot be reduced completely with only engine measures today. The present paper describes two different possibilities for the simultaneous in-cylinder reduction of soot and nitrogen oxide emissions. One possibility is the optimization of the injection process with a new injection strategy the other one is the use of water diesel emulsions with the conventional injection system. The new injection strategy for this experimental part of the study overcomes the problem of increased soot emissions with pilot injection by separating the injections spatially and therefore on the one hand reduces the soot formation during the early stages of the combustion and on the other hand increases the soot oxidation later during the combustion. Another method to reduce the emissions is the introduction of water into the combustion chamber. Emulsions of water and fuel offer the potential to simultaneously reduceNOxand soot emissions while maintaining a high-thermal efficiency. This article presents a theoretical investigation of the use of fuel-water emulsions in DI-Diesel engines. The numerical simulations are carried out with the 3D-CFD code KIVA3V. The use of different water diesel emulsions is investigated and assessed with the numerical model.

Investigation of the Early Soot Formation Process in a Transient Spray Flame Via Spectral Measurements of Laser-Induced Emissions

2006 ◽  
Vol 7 (2) ◽  
pp. 93-101 ◽  
Author(s):  
T Aizawa ◽  
H Kosaka
Keyword(s):  
Formation Process ◽  
Soot Formation ◽  
Yttrium Aluminium Garnet ◽  
Two Dimensional ◽  
Spectral Measurements ◽  
Cross Sectional ◽  
Soot Particles ◽  
Nozzle Orifice ◽  
Spray Flame ◽  
Soot Precursors

In order to investigate the early soot formation process in a diesel spray flame, two-dimensional imaging and spectral measurements of laser-induced emission from soot precursors and soot particles in a transient spray flame achieved in a rapid compression machine (2.8 MPa, 710 K) were conducted. The 3rd harmonic (355 nm) and 4th harmonic (266 nm) Nd: YAG (neodymium-doped yttrium aluminium garnet) laser pulses were used as the light source for laser-induced fluorescence (LIF) from soot precursors and laser-induced incandescence (LII) from soot particles in the spray flame. The two-dimensional imaging covered an area between 30 and 55 mm downstream from the nozzle orifice. The results of two-dimensional imaging showed that strong laser-induced emission excited at 266 nm appears only on the laser incident side of the spray flame, in contrast to an entire cross-sectional distribution of the emission excited at 355 nm, indicating that 266 nm-excited emitters are stronger absorbers and more abundant than 355 nm-excited emitters in the spray flame. The spectral measurements were conducted at three different positions, 35, 45, and 55 mm downstream from the nozzle orifice, along the central axis of the spray, where LIF from soot precursors was observed in a previous two-dimensional imaging study. The spectra measured in upstream positions showed that broad emission peaked at around 400–500 nm, which is attributable to LIF from polycyclic aromatic hydrocarbons (PAHs). The spectra measured in downstream positions appeared very much like grey-body emission from soot particles.

A numerical study on soot formation and oxidation for a direct injection diesel engine

2003 ◽  
Vol 217 (5) ◽  
pp. 403-413 ◽  
Author(s):  
N Sung ◽  
S Lee ◽  
H Kim ◽  
B Kim
Keyword(s):  
Diesel Engine ◽  
Combustion Temperature ◽  
Soot Formation ◽  
Direct Injection ◽  
Soot Oxidation ◽  
Operating Conditions ◽  
Injection Timing ◽  
Mixture Ratio ◽  
Soot Particles ◽  
Carbon Radicals

A numerical cycle model is developed to investigate the soot production in a direct injection (DI) diesel engine. The Surovikin and Fusco models for soot formation and the Nagle model for soot oxidation are used with the KIVA-3V code. In the Surovikin model, carbon radicals are produced from pyrolysis of fuel and soot particles grow through collisions with fuel molecules. In the Fusco model, the carbon radicals and acetylene are formed from pyrolysis of fuel. There, acetylene works for the growth of soot particles. From investigation of the e. ects of the operating conditions on soot formation and oxidation, it is found that soot formation is mainly governed by fuel concentration and combustion temperature and soot oxidation is more dependent on combustion temperature. The air-fuel ratio a. ects soot formation more than injection timing. For a stoichiometric mixture ratio, soot formation is increased because of the high combustion temperature.

Effects of Cavitation in Common-Rail Diesel Nozzles on the Soot Formation Process

2013 ◽  
Author(s):  
Francisco Payri ◽  
J. Javier Lopez ◽  
Antonio Garcia ◽  
Oscar A. de la Garza de Leon ◽  
Sebastien Houille
Keyword(s):  
Formation Process ◽  
Soot Formation ◽  
Common Rail

scholarly journals A Comparison of Methyl Decanoate and Tripropylene Glycol Monomethyl Ether for Soot-Free Combustion in an Optical Direct-Injection Diesel Engine

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Cosmin E. Dumitrescu ◽  
A. S. Cheng ◽  
Eric Kurtz ◽  
Charles J. Mueller
Keyword(s):  
High Speed ◽  
Fuel Injection ◽  
Soot Formation ◽  
Monomethyl Ether ◽  
Mie Scattering ◽  
Compression Ignition Engine ◽  
Glycol Monomethyl Ether ◽  
Soot Emissions ◽  
Lift Off ◽  
Methyl Decanoate

Oxygenated fuels have beneficial effects for leaner lifted-flame combustion (LLFC), a nonsooting mode of mixing-controlled combustion associated with lift-off length equivalence ratios below approximately 2. A single-cylinder heavy-duty optical compression-ignition engine was used to compare neat methyl decanoate (MD) and T50, a 50/50 blend by volume of tripropylene glycol monomethyl ether (TPGME) and #2 ultralow sulfur emissions-certification diesel fuel (CF). High-speed, simultaneous imaging of natural luminosity (NL) and chemiluminescence (CL) were employed to investigate the ignition, combustion, and soot formation/oxidation processes at two injection pressures and three dilution levels. Additional Mie scattering measurements observed fuel-property effects on the liquid length of the injected spray. Results indicate that both MD and T50 effectively eliminated engine-out smoke emissions by decreasing soot formation and increasing soot oxidation during and after the end of fuel injection. MD further reduced soot emissions by 50–90% compared with T50, because TPGME could not completely compensate for the aromatics in the CF. Despite the low engine-out soot emissions, both fuels produced in-cylinder soot because the equivalence ratio at the lift-off length never reached the nonsooting limit. With respect to the other engine-out emissions, T50 had up to 16% higher nitrogen oxides (NOx) emissions compared with MD, but neither fuel showed the traditional soot-NOx trade-off associated with conventional mixing-controlled combustion. In addition, T50 had up to 15% and 26% lower unburned hydrocarbons (HC) and CO emissions, respectively, compared with MD.

Soot Formation in Diesel Fuel Jets Near the Lift-Off Length

2006 ◽  
Vol 7 (2) ◽  
pp. 103-130 ◽  
Author(s):  
L M Pickett ◽  
D L Siebers
Keyword(s):  
Heat Release ◽  
Diesel Fuel ◽  
Soot Formation ◽  
Air Entrainment ◽  
Operating Conditions ◽  
Entrainment Rate ◽  
Fuel Type ◽  
Fuel Jet ◽  
Air Mixing ◽  
Lift Off

Soot formation in the region downstream of the lift-off length of diesel fuel jets was investigated in an optically accessible constant-volume combustion vessel under quiescent-type diesel engine conditions. Planar laser-induced incandescence and line-of-sight laser extinction were used to determine the location of the first soot formation during mixing-controlled combustion. OH chemiluminescence imaging was used to determine the location of high-heat-release reactions relative to the soot-forming region. The primary parameters varied in the experiments were the sooting propensity of the fuel and the amount of fuel-air premixing that occurs upstream of the lift-off length. The fuels considered in order of increasing sooting propensity were: an oxygenated fuel blend (T70), a blend of diesel cetane-number reference fuels (CN80), and a #2 diesel fuel (D2). Fuel-air mixing upstream of the lift-off length was varied by changing ambient gas and injector conditions, which varied either the lift-off length or the air entrainment rate into the fuel jet relative to the fuel injection rate. Results show that soot formation starts at a finite distance downstream of the lift-off length and that the spatial location of soot formation depends on the fuel type and operating conditions. The distance from the lift-off length to the location of the first soot formation increases as the fuel sooting propensity decreases (i.e. in the order D2 < CN80 < T70). At the baseline operating conditions, the most upstream soot formation occurs at the edges of the jet for D2 and CN80, while for T70 the soot formation is confined to the jet central region. When conditions are varied to produce enhanced fuel-air mixing upstream of the lift-off length in D2 fuel jets, the initial soot formation shifts towards the fuel jet centre and eventually no soot is formed. For all experimental conditions, the observed location of soot formation relative to the heat-release location (lift-off) suggests that soot formation occurs in a mixture of combustion products originating from partially premixed reactions and a diffusion flame. The results also imply that soot precursor formation rates depend strongly on fuel type in the region between the lift-off length and the first soot formation.

A Comparison of Methyl Decanoate and Tripropylene Glycol Monomethyl Ether for Soot-Free Combustion in an Optical Direct-Injection Diesel Engine

2016 ◽  
Author(s):  
Cosmin E. Dumitrescu ◽  
A. S. (Ed) Cheng ◽  
Eric Kurtz ◽  
Charles J. Mueller
Keyword(s):  
High Speed ◽  
Soot Formation ◽  
Monomethyl Ether ◽  
Mie Scattering ◽  
Compression Ignition Engine ◽  
Glycol Monomethyl Ether ◽  
Soot Emissions ◽  
Lift Off ◽  
Oxygenated Fuels ◽  
Methyl Decanoate

Oxygenated fuels have been reported to have beneficial effects for leaner lifted-flame combustion (LLFC), a non-sooting mode of mixing-controlled combustion associated with lift-off length equivalence ratios below approximately 2. A single-cylinder heavy-duty optical compression-ignition engine was used to compare two oxygenated fuels: neat methyl decanoate (MD) and T50, a 50/50 blend by volume of tripropylene glycol monomethyl ether (TPGME) and #2 ultra-low sulfur emissions-certification diesel fuel (CF). High-speed, simultaneous imaging of natural luminosity and chemiluminescence were employed to investigate the ignition, combustion, and soot formation/oxidation processes at two injection pressures and three dilution levels. Additional Mie scattering measurements were employed to observe fuel-property effects on the liquid length of the injected spray. Results indicate that both MD and T50 reduced considerably the engine-out smoke emissions by decreasing soot formation and/or increasing soot oxidation during and after the end of fuel injection. MD further reduced soot emissions by 50–90% compared with T50, because TPGME could not completely compensate for the aromatics in the CF. Despite the low engine-out soot emissions, both fuels produced in-cylinder soot because the equivalence ratio at the lift-off length never reached the non-sooting limit. With respect to the other engine-out emissions, T50 had up to 16% higher NOx emissions compared with MD, but neither fuel showed the traditional soot-NOx trade-off associated with conventional mixing-controlled combustion. In addition, T50 had up to 15% and 26% lower unburned hydrocarbons (HC) and carbon monoxide (CO) emissions, respectively, compared with MD.

Numerical Investigation of Fuel Effects on Soot Emissions at Heavy-Duty Diesel Engine Conditions

2018 ◽  
Author(s):  
Meng Tang ◽  
Yuanjiang Pei ◽  
Yu Zhang ◽  
Michael Traver ◽  
David Cleary ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Turbulence Model ◽  
Soot Formation ◽  
Heavy Duty ◽  
Cfd Simulations ◽  
Heavy Duty Diesel Engine ◽  
Soot Emissions ◽  
Heavy Duty Diesel ◽  
Lift Off ◽  
Soot Model

Gasoline compression ignition (GCI) engine technology has shown the potential to achieve high fuel efficiency with low criteria pollutant emissions. In order to guide the design and optimization of GCI combustion, it is essential to develop high-fidelity simulation tools. Building on the previous work in computational fluid dynamic (CFD) simulations of spray combustion, this work focuses on predicting the soot emissions in a constant-volume vessel representative of heavy-duty diesel engine applications for an ultra-low sulfur diesel (ULSD) and a high reactivity (Research Octane Number 60) gasoline, and comparing the soot evolution characteristics of the two fuels. Simulations were conducted using both Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) turbulence models. Extensive model validations were performed against the experimental soot emissions data for both fuels. It was found that the simulation results using the LES turbulence model agreed better with the measured ignition delays and liftoff lengths than the RANS turbulence model. In addition, two soot models were evaluated in the current study, including an empirical two-step soot formation and oxidation model, and a detailed soot model that involves poly-aromatic hydrocarbon (PAH) chemistry. Validations showed that the separation of the flame lift-off location and the soot lift-off location and the relative natural luminosity signals were better predicted by the detailed soot model combined with the LES turbulence model. Qualitative comparisons of simulated local soot concentration distributions against experimental measurements in the literature confirmed the model’s performance. CFD simulations showed that the transition of domination from soot formation to soot oxidation was fuel-dependent, and the two fuels exhibited different temporal and spatial characteristics of soot emissions. CFD simulations also confirmed the lower sooting propensity of gasoline compared to ULSD under all investigated conditions.

scholarly journals Optical study on characteristics of non-reacting and reacting diesel spray with different strategies of split injection

2018 ◽  
Vol 20 (6) ◽  
pp. 606-623 ◽  
Author(s):  
Jose M Desantes ◽  
José M García-Oliver ◽  
Antonio García ◽  
Tiemin Xuan
Keyword(s):  
High Speed ◽  
Dwell Time ◽  
Soot Formation ◽  
Operating Conditions ◽  
Split Injection ◽  
Injection Duration ◽  
Soot Mass ◽  
Lift Off ◽  
Combustion Processes ◽  
Injection Strategies

Even though studies on split-injection strategies have been published in recent years, there are still many remaining questions about how the first injection affects the mixing and combustion processes of the second one by changing the dwell time between both injection events or by the first injection quantity. In this article, split-injection diesel sprays with different injection strategies are investigated. Visualization of n-dodecane sprays was carried out under both non-reacting and reacting operating conditions in an optically accessible two-stroke engine equipped with a single-hole diesel injector. High-speed Schlieren imaging was applied to visualize the spray geometry development, while diffused background-illumination extinction imaging was applied to quantify the instantaneous soot production (net result of soot formation and oxidation). For non-reacting conditions, it was found that the vapor phase of second injection penetrates faster with a shorter dwell time and independently of the duration of the first injection. This could be explained in terms of one-dimensional spray model results, which provided information on the local mixing and momentum state within the flow. Under reacting conditions, interaction between the second injection and combustion recession of the first injection is observed, resulting in shorter ignition delay and lift-off compared to the first injection. However, soot production behaves differently with different injection strategies. The maximum instantaneous soot mass produced by the second injection increases with a shorter dwell time and with longer first injection duration.

An experimental study with renewable fuels using ECN Spray A and D nozzles

2021 ◽  
pp. 146808742110312
Author(s):  
José V Pastor ◽  
José M García-Oliver ◽  
Carlos Micó ◽  
Alba A García-Carrero
Keyword(s):  
High Speed ◽  
Soot Formation ◽  
Road Transport ◽  
Operating Conditions ◽  
Nozzle Geometry ◽  
Transport Sector ◽  
The Road ◽  
Auto Ignition ◽  
Lift Off ◽  
Oxygenated Fuels

The decarbonization process of the automotive industry and the road transport sector has raised the interest on the development of cleaner fuels. A proper characterization of their properties and behavior under different operating conditions is mandatory to achieve an effective implementation in commercial engines. With this objective, the current work presents a comparison of two injectors from the Engine Combustion Network (ECN), namely Spray A and Spray D injectors, in terms of spray characteristics and combustion behavior for different fuels: diesel, dodecane, Hydrotreated Vegetable Oil (HVO), and two types of oxymethylene ethers (OME1 and OME x). The aim is to analyze how differences in nozzle geometry affect the behavior of different types of fuels. The experiments were carried out in a High Temperature and High Pressure test rig and operating conditions were chosen following ECN guidelines. Visualization techniques such as high speed schlieren imaging, OH* chemiluminescence and diffused back illumination were implemented to analyze the differences in liquid length, vapor penetration, auto ignition, flame lift-off length, and soot formation for both nozzles. In general, results showed the same trend for all the fuels tested: longer liquid length and faster vapor penetration for Spray D, as well as higher ignition delay and longer lift-off length. However, it was found that these parameters were less sensitive to the nozzle diameter for the oxygenated fuels tested. Furthermore, a different trend was observed for OME1, in terms of ignition behavior, in comparison to the other fuels. In terms of soot production, the Spray D nozzle increases its formation with the non-oxygenated fuels. In contrast, no soot was observed with the oxygenated ones under any operating conditions.

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