A Phenomenological Engine Model for Direct Injection of Liquid Fuels, Spray Penetration, Vaporization, Ignition Delay, and Combustion

2007 ◽  
Author(s):  
Robert M. Siewert
Keyword(s):  
Ignition Delay ◽  
Direct Injection ◽  
Liquid Fuels ◽  
Spray Penetration ◽  
Engine Model

Effect of n-heptane and n-decane on exhaust odour in direct injection diesel engines

2005 ◽  
Vol 219 (4) ◽  
pp. 565-571 ◽  
Author(s):  
M M Roy
Keyword(s):  
Direct Effect ◽  
Diesel Fuel ◽  
Diesel Engines ◽  
Ignition Delay ◽  
Boiling Point ◽  
Alternative Fuels ◽  
Direct Injection ◽  
Cetane Number ◽  
Mixture Formation ◽  
Incomplete Combustion

This study investigated the effect of n-heptane and n-decane on exhaust odour in direct injection (DI) diesel engines. The prospect of these alternative fuels to reduce wall adherence and overleaning, major sources of incomplete combustion, as well as odorous emissions has been investigated. The n-heptane was tested as a low boiling point fuel that can improve evaporation as well as wall adherence. However, the odour is a little worse with n-heptane and blends than that of diesel fuel due to overleaning of the mixture. Also, formaldehyde (HCHO) and total hydrocarbon (THC) in the exhaust increase with increasing n-heptane content. The n-decane was tested as a fuel with a high cetane number that can improve ignition delay, which has a direct effect on wall adherence and overleaning. However, with n-decane and blends, the odour rating is about 0.5-1 point lower than for diesel fuel. Moreover, the aldehydes and THC are significantly reduced. This is due to less wall adherence and proper mixture formation.

Simulation of a Single Cylinder Diesel Engine Under Cold Start Conditions Using Simulink

2000 ◽  
Vol 123 (1) ◽  
pp. 117-124 ◽  
Author(s):  
H.-Q. Liu ◽  
N. G. Chalhoub ◽  
N. Henein
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Cold Start ◽  
Operating Conditions ◽  
Combustion Model ◽  
Nonlinear Dynamic Model ◽  
Single Cylinder ◽  
Engine Model ◽  
Simulink Model ◽  
Engine Components

A nonlinear dynamic model is developed in this study to simulate the overall performance of a naturally aspirated, single cylinder, four-stroke, direct injection diesel engine under cold start and fully warmed-up conditions. The model considers the filling and emptying processes of the cylinder, blowby, intake, and exhaust manifolds. A single zone combustion model is implemented and the heat transfer in the cylinder, intake, and exhaust manifolds are accounted for. Moreover, the derivations include the dynamics of the crank-slider mechanism and employ an empirical model to estimate the instantaneous frictional losses in different engine components. The formulation is coded in modular form whereby each module, which represents a single process in the engine, is introduced as a single block in an overall Simulink engine model. The numerical accuracy of the Simulink model is verified by comparing its results to those generated by integrating the engine formulation using IMSL stiff integration routines. The engine model is validated by the close match between the predicted and measured cylinder gas pressure and engine instantaneous speed under motoring, steady-state, and transient cold start operating conditions.

Ozone-Assisted Combustion—Part I: Literature Review and Kinetic Study Using Detailed n-Heptane Kinetic Mechanism

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Christopher Depcik ◽  
Michael Mangus ◽  
Colter Ragone
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Atomic Oxygen ◽  
Direct Injection ◽  
Kinetic Mechanism ◽  
Combustion Model ◽  
Ozone Decomposition ◽  
Compression Ignition ◽  
Review Of The Literature ◽  
Compression Ignition Engine

In this first paper, the authors undertake a review of the literature in the field of ozone-assisted combustion in order to summarize literature findings. The use of a detailed n-heptane combustion model including ozone kinetics helps analyze these earlier results and leads into experimentation within the authors' laboratory using a single-cylinder, direct-injection compression ignition engine, briefly discussed here and in more depth in a following paper. The literature and kinetic modeling outcomes indicate that the addition of ozone leads to a decrease in ignition delay, both in comparison to no added ozone and with a decreasing equivalence ratio. This ignition delay decrease as the mixture leans is counter to the traditional increase in ignition delay with decreasing equivalence ratio. Moreover, the inclusion of ozone results in slightly higher temperatures in the cylinder due to ozone decomposition, augmented production of nitrogen oxides, and reduction in particulate matter through radial atomic oxygen chemistry. Of additional importance, acetylene levels decrease but carbon monoxide emissions are found to both increase and decrease as a function of equivalence ratio. This work illustrates that, beyond a certain level of assistance (approximately 20 ppm for the compression ratio of the authors' engine), adding more ozone has a negligible influence on combustion and emissions. This occurs because the introduction of O3 into the intake causes a temperature-limited equilibrium set of reactions via the atomic oxygen radical produced.

Turbocharged CNG Engines for Urban Transportation: Evaluation of Turbolag Reduction Strategies by Means of Computational Analyses

2009 ◽  
Author(s):  
Mirko Baratta ◽  
Ezio Spessa
Keyword(s):  
Public Transportation ◽  
High Performance ◽  
Exhaust Valve ◽  
Liquid Fuels ◽  
Transient Condition ◽  
Specific Reference ◽  
Engine Model ◽  
Spark Timing ◽  
Pollutant Reduction ◽  
1D Numerical Simulation

Nowadays, many urban buses for public transportation are fuelled by compressed natural gas (CNG), due to its potential for energy saving and pollutant reduction, with specific reference to particulate matter emissions. However, turbocharging is required to recover the gaseous-fuel related power gap with respect to more traditional engines running on liquid fuels. Therefore, turbolag reduction is fundamental to achieve high performance during engine transients. Significant support for the study of turbocharged CNG engines and guidelines for the turbomatching process can be provided by 1D numerical simulation tools. In this paper, the topic of turbolag reduction is analyzed, and different strategies, namely, Early-Exhaust Valve Opening-Variable Valve Actuation (E-EVO-VVA) and spark timing control for combustion retard (ComR), are analyzed by means of a specifically developed and calibrated GT-POWER® engine model. Tip-in maneuvers in which the engine was coupled to a torque hydraulic converter under stall conditions were investigated, so as to reproduce a typical load transient condition for an urban bus accelerating from engine idle. The best improvement of turbolag was obtained by combining E-EVO-VVA and ComR, with a reduction of turbolag ranging from 60% to 70%. When a limit on the incylinder pressure is introduced, in order to prevent excessive exhaust valve mechanical stresses, the higher achievable reduction in turbolag was found to be between 35% and 45%.

A Proposed Biodiesel Combustion Kinetics Based on the Computational Fluid Dynamics Results in an Ignition Quality Tester

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Mahmoud Elhalwagy ◽  
Chao Zhang
Keyword(s):  
Methyl Ester ◽  
Ignition Delay ◽  
Methyl Esters ◽  
Direct Injection ◽  
Combustion Process ◽  
Major Fatty Acid ◽  
Combustion Behavior ◽  
Ignition Quality ◽  
Reaction Constants ◽  
Ignition Quality Tester

In this paper, five biodiesel global combustion decomposition steps are added to a surrogate mechanism to accurately represent the chemical kinetics of the decomposition of different levels of saturation of biodiesel, which are represented by five major fatty acid methyl esters. The reaction constants were tuned based on the results from the numerical simulations of the combustion process in an ignition quality tester (IQT) in order to obtain accurate cetane numbers. The prediction of the complete thermophysical properties of the five constituents is also carried out to accurately represent the physics of the spray and vaporization processes. The results indicated that the combustion behavior is controlled more by the spray and breakup processes for saturated biodiesel constituents than by the chemical delay, which is similar to the diesel fuel combustion behavior. The chemical delay and low temperature reactions were observed to have greater effects on the combustion and ignition delay for the cases of the unsaturated biodiesels. The comparison between the physical ignition delay and overall ignition delay between the saturated and unsaturated biodiesel constituents has also confirmed those stronger effects for the physical delay in the saturated compounds as compared to the unsaturated compounds. The validation of the proposed model is conducted for the simulations of two direct injection diesel engines using palm methyl ester and rape methyl ester.

Numerical Studies of Glow Plug Shield on Natural Gas Ignition Characteristics in a CI Engine

2016 ◽  
Author(s):  
Kang Pan ◽  
James S. Wallace
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Fuel Injection ◽  
Numerical Study ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Injection Angle ◽  
Glow Plug ◽  
Gas Ignition ◽  
Ignition And Combustion

This paper presents a numerical study on fuel injection, ignition and combustion in a direct-injection natural gas (DING) engine with ignition assisted by a shielded glow plug (GP). The shield geometry is investigated by employing different sizes of elliptical shield opening and changing the position of the shield opening. The results simulated by KIVA-3V indicated that fuel ignition and combustion is very sensitive to the relative angle between the fuel injection and the shield opening, and the use of an elliptical opening for the glow plug shield can reduce ignition delay by 0.1∼0.2ms for several specific combinations of the injection angle and shield opening size, compared to a circular shield opening. In addition, the numerical results also revealed that the natural gas ignition and flame propagation will be delayed by lowering a circular shield opening from the fuel jet center plane, due to the blocking effect of the shield to the fuel mixture, and hence it will reduce the DING performance by causing a longer ignition delay.

Sign in / Sign up

Export Citation Format

Share Document