Application of a Phenomenological Soot Model for Diesel Engine Combustion

2008 ◽  
Author(s):  
Xiaobei Cheng ◽  
Hongling Jv ◽  
Yifeng Wu
Keyword(s):  
Diesel Engine ◽  
Chemical Reactions ◽  
Oxidation Rate ◽  
Soot Formation ◽  
Soot Oxidation ◽  
Soot Concentration ◽  
Engine Operation ◽  
Soot Particles ◽  
Turbulent Eddies ◽  
Soot Model

The application of the improved CFD code for the simulation of combustion and emission formation in a high-speed diesel engine has been presented and discussed. The soot concentration transport equation is found and solved together with all other flow equations. A slip correction factor is introduced into this equation. In turbulent combustion, the soot particles are contained within the turbulent eddies, and burnt up swiftly with the dissipation of these eddies in the soot oxidation zone. However, the chemical reactions always process except the dissipation of turbulent eddies and the intermixing of soot particles and turbulent eddies. The soot oxidation rate should be controlled simultaneity by the chemical reactions rate and the dissipation rate of turbulent eddies. A hybrid particle turbulent transport controlled rate and soot oxidation rate model is present in this paper and Soot formation and oxidation processes have been modeled according to this model. A reasonable agreement of the measured and computed data of in-cylinder pressure, soot, and NO emissions for different engine operation conditions has been made. The precision of simulated soot concentration is improved compare with the commonly Hiroyasu—Nagel—Strickland (HNS) soot model.

scholarly journals An Improved Soot Formation Model for 3D Diesel Engine Simulations

2006 ◽  
Vol 129 (3) ◽  
pp. 877-884 ◽  
Author(s):  
Joan Boulanger ◽  
Fengshan Liu ◽  
W. Stuart Neill ◽  
Gregory J. Smallwood
Keyword(s):  
Diesel Engine ◽  
Soot Formation ◽  
Computing Time ◽  
Combustion Process ◽  
Computational Cost ◽  
Wall Region ◽  
Soot Particles ◽  
Engine Combustion ◽  
Near Wall ◽  
Soot Model

Soot formation phenomenon is far from being fully understood today and models available for simulation of soot in practical combustion devices remain of relatively limited success, despite significant progresses made over the last decade. The extremely high demand of computing time of detailed soot models make them unrealistic for simulation of multidimensional, transient, and turbulent diesel engine combustion. Hence, most of the investigations conducted in real configuration such as multidimensional diesel engines simulation utilize coarse modeling, the advantages of which are an easy implementation and low computational cost. In this study, a phenomenological three-equation soot model was developed for modeling soot formation in diesel engine combustion based on considerations of acceptable computational demand and a qualitative description of the main features of the physics of soot formation. The model was developed based on that of Tesner et al. and was implemented into the commercial STAR-CD™ CFD package. Application of this model was demonstrated in the modeling of soot formation in a single-cylinder research version of Caterpillar 3400 series diesel engine with exhaust gas recirculation (EGR). Numerical results show that the new soot formulation overcomes most of the drawbacks in the existing soot models dedicated to this kind of engineering task and demonstrates a robust and consistent behavior with experimental observation. Compared to the existing soot models for engine combustion modeling, some distinct features of the new soot model include: no soot is formed at low temperature, minimal model parameter adjustment for application to different fuels, and there is no need to prescribe the soot particle size. At the end of expansion, soot is predicted to exist in two separate regions in the cylinder: in the near wall region and in the center part of the cylinder. The existence of soot in the near wall region is a result of reduced soot oxidation rate through heat loss. They are the source of the biggest primary particles released at the end of the combustion process. The center part of the cylinder is populated by smaller soot particles, which are created since the early stages of the combustion process but also subject to intense oxidation. The qualitative effect of EGR is to increase the size of soot particles as well as their number density. This is linked to the lower in-cylinder temperature and a reduced amount of air.

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.

scholarly journals Modeling study of soot formation and oxidation in DI diesel engine using an improved soot model

2014 ◽  
Vol 62 (2) ◽  
pp. 303-312 ◽  
Author(s):  
Xiaobei Cheng ◽  
Liang Chen ◽  
Guang Hong ◽  
Fangqin Yan ◽  
Shijun Dong
Keyword(s):  
Diesel Engine ◽  
Soot Formation ◽  
Di Diesel Engine ◽  
Soot Model ◽  
Modeling Study

Influence of Post-Injection Parameters on Soot Formation and Oxidation in a Common-Rail-Diesel Engine Using Multi-Color-Pyrometry

2012 ◽  
Author(s):  
Christophe Barro ◽  
Frédéric Tschanz ◽  
Peter Obrecht ◽  
Konstantinos Boulouchos
Keyword(s):  
Oxidation Rate ◽  
Time Window ◽  
Soot Formation ◽  
General Rule ◽  
Soot Oxidation ◽  
Lower Amount ◽  
Post Injection ◽  
Heat Addition ◽  
Underlying Mechanisms ◽  
A Minor

The emission trade-off between soot and NOx is an issue of major concern in automotive diesel applications. Measures need to be taken both on the engine and on the aftertreatment sides in order to optimize the engine emissions while maintaining the highest possible efficiency. It is known that post injections have a potential for exhaust soot reduction without any significant influence in the NOx emissions. However, an accurate and general rule of how to parameterize a post injection such that it provides a maximum reduction of soot emissions does not exist. Moreover, the underlying mechanisms are not understood in detail. The experimental investigation presented here provides insight into the fundamental mechanisms of soot formation and reduction due to post injections under different turbulence and reaction kinetic conditions. In parallel to the measurement of soot elementary carbon in the exhaust (using a Photo Acoustic Soot Sensor), the in-cylinder soot formation and oxidation process have been investigated with an Optical Light Probe (OLP). This sensor provides crank angle resolved information about the in-cylinder soot evolution. The experiments confirm conclusions of earlier works that soot reduction due to a post injection is mainly based on two reasons: increased turbulence (from the post injection) during soot oxidation and lower soot formation due to lower amount of fuel in the main combustion at similar load conditions. A third effect of heat addition during the soot oxidation, which was often mentioned in the literature, could not be confirmed. In addition, the experiments show that variations of turbulence (from swirl) and reaction kinetics have a minor influence on the diffusion controlled heat release rate. However, the time phasing of the soot evolution is highly influenced by these variations with only small changes in the peak soot concentration. It is shown that the soot reduction of a post injection depends on the timing. More precisely, the soot reduction capability of a post injection decreases rapidly as soon as its timing is late in the soot oxidation phase. The soot oxidation rate can only be improved by increased turbulence and heat addition from the post injection in a time window before the in-cylinder soot peak occurs. Depending on EGR and swirl level, a maximum dwell time can be defined after which the post injection effect becomes counterproductive with respect to the soot oxidation rate.

scholarly journals Experimental and computational investigation of temperature effects on soot mechanisms

2014 ◽  
Vol 79 (7) ◽  
pp. 881-895 ◽  
Author(s):  
Xiaojie Bi ◽  
Maoyu Xiao ◽  
Xinqi Qiao ◽  
Chia-Fon Lee ◽  
Liu Yu
Keyword(s):  
Ambient Temperature ◽  
Soot Formation ◽  
Oxidation Mechanism ◽  
Soot Oxidation ◽  
Ambient Temperatures ◽  
Operation Conditions ◽  
Constant Volume Chamber ◽  
Soot Mass ◽  
Soot Measurement ◽  
Soot Model

Effects of initial ambient temperatures on combustion and soot emission characteristics of diesel fuel were investigated through experiment conducted in optical constant volume chamber and simulation using phenomenological soot model. There are four difference initial ambient temperatures adopted in our research: 1000 K, 900 K, 800 K and 700 K. In order to obtain a better prediction of soot behavior, phenomenological soot model was revised to take into account the soot oxidation feedback on soot number density and good agreement was observed in the comparison of soot measurement and prediction. Results indicated that ignition delay prolonged with the decrease of initial ambient temperature. The heat release rate demonstrated the transition from mixing controlled combustion at high ambient temperature to premixed combustion mode at low ambient temperature. At lower ambient temperature, soot formation and oxidation mechanism were both suppressed. But finally soot mass concentration reduced with decreasing initial ambient temperature. Although the drop in ambient temperature did not cool the mean in-cylinder temperature during the combustion, it did shrink the total area of local high equivalence ratio, in which soot usually generated fast. At 700 K initial ambient temperature, soot emissions were almost negligible, which indicates that sootless combustion might be achieved at super low initial temperature operation conditions.

Engine Performance and Emissions Formation for RME and Conventional Diesel Oil: A Comparative Study

2009 ◽  
Author(s):  
Junfeng Yang ◽  
Monica Johansson ◽  
Valeri Golovitchev
Keyword(s):  
Diesel Engine ◽  
Comparative Study ◽  
Soot Formation ◽  
Engine Performance ◽  
Oxidation Mechanism ◽  
Diesel Oil ◽  
Engine Operation ◽  
Operation Conditions ◽  
Performance And Emissions ◽  
Engine Performance And Emissions

A comparative study on engine performance and emissions (NOx, soot) formation has been carried out for the Volvo D12C diesel engine fueled by Rapeseed Methyl Ester, RME and conventional diesel oil. The combustion models, used in this paper, are the modifications of those described in [1–2]. After the compilation of liquid properties of RME specified as methyl oleate, C19H36O2, making up 60% of RME. The oxidation mechanism has been compiled based on methyl butanoate ester, mb, C5H10O2 oxidation model [3] supplemented by the sub-mechanisms for two proposed fuel constituent components, methyl decanoate, md, C11H22O2, n-heptane, C7H16, and soot and NOx formations reduced and “tuned” by using the sensitivity analysis. A special global reaction was introduced to “crack” the main fuel into constituent components, md, mb and propyne, C3H4, to reproduce accurately the proposed RME chemical formula. The sub-mechanisms were collected in the general one consisting of 99 species participating in 411 reactions. The combustion mechanism was validated using shock-tube ignition-delay data at diesel engine conditions and flame propagation speeds at atmospheric conditions. The engine simulations were carried out for Volvo D12C engine fueled both RME and conventional diesel oil. The numerical results illustrate that in the case of RME, nearly 100% combustion efficiency was predicted when the cumulative heat release, was compared with the RME LHV, 37.2 kJ/g.. To minimize NOx emissions, the effects of 20–30% EGR levels depending on the engine loads and different injection strategies were analyses. To confirm the optimal engine operation conditions, a special technique based on the time-transient parametric φ-T maps [4] has been used.

Modelling soot formation in a premixed flame using an aromatic-site soot model and an improved oxidation rate

2009 ◽  
Vol 32 (1) ◽  
pp. 639-646 ◽  
Author(s):  
Matthew S. Celnik ◽  
Markus Sander ◽  
Abhijeet Raj ◽  
Richard H. West ◽  
Markus Kraft
Keyword(s):  
Oxidation Rate ◽  
Soot Formation ◽  
Premixed Flame ◽  
Soot Model

scholarly journals An Improved Phenomenological Soot Formation Submodel for Three-Dimensional Diesel Engine Simulations: Extension to Agglomeration of Particles into Clusters

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Joan Boulanger ◽  
W. Stuart Neill ◽  
Fengshan Liu ◽  
Gregory J. Smallwood
Keyword(s):  
Experimental Data ◽  
Diesel Engine ◽  
Oxidation Process ◽  
Soot Formation ◽  
Three Dimensional ◽  
Soot Oxidation ◽  
Heavy Duty ◽  
Heavy Duty Diesel Engine ◽  
Agglomeration Effects ◽  
Heavy Duty Diesel

An extension to a phenomenological submodel for soot formation to include soot agglomeration effects is developed. The improved submodel was incorporated into a commercial computational fluid dynamics code and was used to investigate soot formation in a heavy-duty diesel engine. The results of the numerical simulation show that the soot oxidation process is reduced close to the combustion chamber walls, due to heat loss, such that larger soot particles and clusters are predicted in an annular volume at the end of the combustion cycle. These results are consistent with available in-cylinder experimental data and suggest that the cylinder of a diesel engine must be split into several volumes, each of them with a different role regarding soot formation.

Soot Particle Evolution and Transport in a Direct Injection Diesel Engine

2015 ◽  
Vol 74 (3) ◽  
Author(s):  
Muhammad Ahmar Zuber ◽  
Wan Mohd Faizal Wan Mahmood ◽  
Zambri Harun ◽  
Zulkhairi Zainol Abidin
Keyword(s):  
Particle Size ◽  
Soot Particle ◽  
Soot Formation ◽  
Formation Rate ◽  
Soot Oxidation ◽  
Surface Growth ◽  
Number Density ◽  
Coagulation Rate ◽  
Particulate Emission ◽  
Soot Particles

Particle-based in-cylinder soot distribution study is becoming more important as the rules and regulations pertaining to particulate emission of diesel-powered vehicles have been increasingly more stringent. This paper focuses on the investigation of soot size evolution and its distribution and transport inside an engine cylinder. The overall process of soot formation includes soot nucleation, surface growth, oxidation, coagulation and agglomeration. The present study considers only soot surface growth, oxidation and coagulation to predict the in-cylinder soot particle size. The soot surface growth model was based on Hiroyasu’s soot formation model while soot oxidation was referred to Nagle & Strickland-Constable’s soot oxidation model. Coagulation rate was defined using Smoluchowski’s equation with constant proposed by Wersborg. From this study, it is demonstrated that soot particles with relatively larger size are gathered in the centre of the cylinder while smaller soot particles are found to be in the region near the wall. Soot number density is considerably high at the start of combustion and reduces sharply afterward while the soot particle size shows the opposite trend. Soot formation rate was found to be dominant at earlier crank angle and is overcome by soot oxidation and coagulation processes that caused lower soot number density but higher soot particle size.  

Transient Development of Flame and Soot Distribution in Laminar Diffusion Flame With Preheated Air

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Bijan Kumar Mandal ◽  
Amitava Sarkar ◽  
Amitava Datta
Keyword(s):  
Diffusion Flame ◽  
Volume Fraction ◽  
Soot Formation ◽  
Initial Period ◽  
Qualitative Difference ◽  
Soot Volume Fraction ◽  
Soot Oxidation ◽  
Average Diameter ◽  
Conservation Equations ◽  
Soot Particles

A numerical investigation of the transient development of flame and soot distributions in a laminar axisymmetric coflowing diffusion flame of methane in air has been carried out considering the air preheating effect. The gas phase conservation equations of mass, momentum, energy, and species concentrations along with the conservation equations of soot mass concentration and number density are solved simultaneously, with appropriate boundary conditions, by an explicit finite difference method. Average soot diameters are then calculated from these results. It is observed that the soot is formed in the flame when the temperature exceeds 1300 K. The contribution of surface growth toward soot formation is more significant compared with that of nucleation. Once the soot particles reach the high temperature oxygen-enriched zone beyond the flame, the soot oxidation becomes important. During the initial period, when soot oxidation is not contributing significantly, some of the soot particles escape into the atmosphere. However, under steady condition the exhaust product gas is nonsooty. Preheating of air increases the soot volume fraction significantly. This is both due to more number of soot particles and the increase in the average diameter. However, preheating of air does not cause a qualitative difference in the development of the soot-laden zone during the flame transient period.

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