Showing papers on "Spark-ignition engine published in 2003"

Combustion in Gas Fueled Compression: Ignition Engines of the Dual Fuel Type

Abstract: In the dual fuel engine much of the energy release comes from the combustion of the gaseous fuel white only a small amount of diesel liquid fuel provides ignition through timed cylinder injection. Such operation with optimum conversion methods has the potential to provide operational characteristics that are comparable or superior to those of the corresponding diesel or spark ignition engines. There characteristics may be realized only if sufficiently effective measures can be ensured both for the avoidance of knock, usually at high loads, and incomplete gaseous fuel utilization at relatively light loads. An objective of this contribution is to demonstrate that the main effort needed to overcome the problems associated with the operation of gas fueled dual fuel engines is via a better control of the relatively complex processes of combustion. Both experimental and analytical modeling procedures for effecting optimum improvement to the combustion process are described.

A Predictive Ignition Delay Correlation Under Steady-State and Transient Operation of a Direct Injection Diesel Engine

Abstract: Available correlations for the ignition delay in pulsating, turbulent, two-phase, reacting mixtures found in a diesel engine often have limited predictive ability, especially under transient conditions. This study focuses on the development of an ignition delay correlation, based on engine data, which is suitable for predictions under both steady-state and transient conditions. Ignition delay measurements were taken on a heavy-duty diesel engine across the engine speed/load spectrum, under steady-state and transient operation. The dynamic start of injection was calculated by using a skip-fire technique to determine the dynamic needle lift pressure from a measured injection pressure profile. The dynamic start of combustion was determined from the second derivative of measured cylinder pressure. The inferred ignition delay measurements were correlated using a modified Arrhenius expression to account for variations in fuel/air composition during transients. The correlation has been compared against a number of available correlations under steady-state conditions. In addition, comparisons between measurements and predictions under transient conditions are made using the extended thermodynamic simulation framework of Assanis and Heywood. It is concluded that the proposed correlation provides better predictive capability under both steady-state and transient operation.

Control device for spark-ignition engine

Abstract: The invention is intended to provide improved emission-cleaning performance by use of a three-way catalyst alone, without the need for a lean NOx catalyst, while ensuring a fuel economy improvement effect of lean burn operation A multicylinder spark-ignition engine is constructed such that, in a pair of preceding and following cylinders whose exhaust and intake strokes overlap each other, burned gas discharged from the preceding cylinder (2A, 2D) which is currently in the exhaust stroke is introduced directly into the following cylinder (2B, 2C) which is currently in the intake stroke through an intercylinder gas channel (22) and gas discharged from only the following cylinder (2B, 2C) is led to an exhaust passage (20) provided with a three-way catalyst (24) in a low-load, low-speed operating range Fuel supply to the individual cylinders is controlled in such a manner that combustion in the preceding cylinder (2A, 2D) is made under lean mixture conditions at an air-fuel ratio larger than the stoichiometric air-fuel ratio by a specific amount and combustion in the following cylinder (2B, 2C) is made under conditions of the stoichiometric air-fuel ratio created by supplying fuel to the burned gas introduced from the preceding cylinder (2A, 2D)

Effect of Biodiesel Utilization of Wear of Vital Parts in Compression Ignition Engine

Abstract: The combustion related properties of vegetable oils are somewhat similar to diesel oil Neat vegetable oils or their blends with diesel, however, pose various long-term problems in compression ignition engines, eg, poor atomization characteristics, ring-sticking, injector coking, injector deposits, injector pump failure, and lube oil dilution by crank-case polymerization These undesirable features of vegetable oils are because of their inherent properties like high viscosity, low volatility, and polyunsaturated character Linseed oil methyl ester (LOME) was prepared using methanol for long-term engine operations The physical and combustion-related properties of the fuels thus developed were found to be closer to that of the diesel oil A blend of 20 percent was selected as optimum biodiesel blend Two similar new engines were completely disassembled and subjected to dimensioning of various vital moving parts and then subjected to long-term endurance tests on 20 percent biodiesel blend and diesel oil, respectively After completion of the test, both the engines were again disassembled for physical inspection and wear measurement of various vital parts The physical wear of various vital parts, injector coking, carbon deposits on piston, and ring sticking were found to be substantially lower in case of 20 percent biodiesel-fuelled engine The lubricating oil samples drawn from both engines were subjected to atomic absorption spectroscopy for measurement of various wear metal traces present AAS tests confirmed substantially lower wear and thus improved life for biodiesel operated engines

Lean-burn characteristics of a gasoline engine enriched with hydrogen from a plasmatron fuel reformer

Abstract: When hydrogen is added to a gasoline fueled spark ignition engine the lean limit of the engine can be extended. Lean running engines are inherently more efficient and have the potential for significantly lower NOx emissions. In the engine concept examined here, supplemental hydrogen is generated on-board the vehicle by diverting a fraction of the gasoline to a plasmatron where a partial oxidation reaction is initiated with an electrical discharge, producing a plasmatron gas containing primarily hydrogen, carbon monoxide, and nitrogen. Two different gas mixtures were used to simulate the plasmatron output. An ideal plasmatron gas (H 2 , CO, and N 2 ) was used to represent the output of the theoretically best plasmatron. A typical plasmatron gas (H 2 , CO, N 2 , and CO 2 ) was used to represent the current output of the plasmatron. A series of hydrogen addition experiments were also performed to quantify the impact of the non-hydrogen components in the plasmatron gas. Various amounts of plasmatron gas were used, ranging from the equivalent of 10%-30% of the gasoline being reformed in the plasmatron. All of the data was compared to a baseline case of the engine operating stoichiometrically on gasoline alone. It was found that the peak net indicated fuel conversion efficiency of the system was increased 12% over the baseline case. In addition, at this peak efficiency point the engine out NOx emissions decreased by 94% (165ppm vs. 2800ppm) while the hydrocarbon emissions decreased by 6%. In the data analysis, the relative air/fuel ratio was found to be a inadequate measure of mixture dilution. Two dilution parameters were defined and used. The volumetric Dilution Parameter, VDP, represents the heating value per unit volume of the air/fuel mixture. Pumping work reductions due to mixture dilution correlate with VDP. The Thermal Dilution Parameter, TDP, represents the heating value per unit heat capacity of the air/fuel mixture. Combustion and emissions parameters correlate with TDP.

Characteristics of Homogeneous Charge Compression Ignition (HCCI) Engine Operation for Variations in Compression Ratio, Speed, and Intake Temperature While Using n-Butane as a Fuel

Abstract: In this paper, some basic properties of homogeneous charge compression ignition operation are reported. The effect of inlet temperature, compression ratio and engine speed on the homogeneous charge compression ignition (HCCI) operating ranges were evaluated in a CFR engine using n-butane as a fuel. The minimum and maximum loads for HCCI operation were determined using criteria of coefficient of variation of the indicated mean effective pressure and the derivative of in-cylinder pressure, respectively. Exhaust emissions, particularly hydrocarbons, were measured using a Fourier transform infrared spectrometer. The concentration of intermediate hydrocarbon species rapidly decreased as the magnitude of the energy release increased. Hydrocarbon emission at the maximum HCCI load mainly consists of the fuel itself, which is probably emitted from colder areas in the combustion chamber Finally, the relationship between IMEPCOV and ISFC is discussed.

Spark ignition engine control device

Abstract: For the purpose of improving the fuel efficiency by lean combustion and enhancing the fuel efficiency improvement effects by performing compression ignition efficiently in some cylinders, a multi-cylinder spark ignition engine is constructed such that exhaust gas, that is exhausted from preceding cylinders 2A, 2D on the exhaust stroke side among pairs of cylinders whose exhaust stroke and intake stroke overlap in a low load, low rotational speed region, is directly introduced through an inter-cylinder gas passage 22 into following cylinders 2B, 2C on the intake stroke side and only gas exhausted from the following cylinders 2B, 2C is fed to an exhaust passage 20, which is provided with a three-way catalyst 24. Combustion controller is provided that controls the combustion of each of the cylinders such that combustion is conducted by forced ignition in a condition in which the air/fuel ratio is a lean air/fuel ratio which is larger by a prescribed amount than the stoichiometric air/fuel ratio in the preceding cylinders 2A, 2D and, in the following cylinders 2B, 2C, fuel is supplied to burnt gas of lean air/fuel ratio introduced from the preceding cylinders 2A, 2D and combustion is conducted by compression ignition.

Spark-ignition engine controller

Abstract: An object of the present invention is to improve fuel economy by means of lean combustion, and in particular to improve fuel economy on a low load side and during idling. Burned gas discharged from an exhaust stroke side preceding cylinder of a pair of cylinders having an overlapping exhaust stroke and intake stroke is introduced as is into an intake stroke side following cylinder through an intercylinder gas channel, and only the gas which is discharged from the following cylinder is led into an exhaust passage. Particularly during low loads and idling, combustion is performed in the preceding cylinder at an ultra-lean air-fuel ratio of at least three times the stoichiometric air-fuel ratio, and in the following cylinder, combustion is performed by spark ignition at a substantially stoichiometric air-fuel ratio by feeding fuel to the burned gas introduced from the preceding cylinder. In the following cylinder, combustion is performed through compression ignition in accordance with increases in the load.

Optimizing Engine Concepts by Using a Simple Model for Knock Prediction

Abstract: This licentiate thesis concerns the modeling of spark ignition engine combustion for use in one dimensional simulation tools. Modeling of knock is of particular interest when modeling turbocharged engines since knock usually limits the possible engine output at high load. The knocking sound is an acoustic phenomenon with pressure oscillations triggered by autoignition of the unburned charge ahead of the propagating flame front and it is potentially damaging to the engine. To be able to predict knock it is essential to predict the temperature and pressure in the unburned charge ahead of the flame front. Hence, an adequate combustion model is needed. The combustion model presented here is based on established correlations of laminar burning velocity which are used to predict changes in combustion duration relative to a base operating condition. Turbulence influence is captured in empirical correlations to the engine operating parameters spark advance and engine speed. This approach makes the combustion model predictive in terms of changes in gas properties such as mixture strength, residual gas content, pressure and temperature. However, a base operating condition and calibration of the turbulence correlations is still needed when using this combustion model. The empirical models presented in this thesis are based on extensive measurements on a turbocharged four cylinder passenger car engine. The knock model is simply a calibration of the Arrhenius type equation for ignition delay in the widely used Livengood-Wu knock integral to the particular fuel and engine used in this work.

Reduction of NOx and Particulate Emissions by Using Oxygen-Enriched Combustion Air in a Locomotive Diesel Engine

Abstract: This paper discusses operational and emissions results obtained with a locomotive (two-cylinder, EMD 567B) research diesel engine when oxygen-enriched combustion air is used. An operating regime was identified in which particulates and NO{sub x} could be reduced simultaneously when the concentration of intake air oxygen, fueling rate, and injection timing were optimized. Using oxygen from an external source, particulates were reduced by approximately 60% and NO{sub x} emissions were reduced by 15--20% with the optimal operating strategy. Higher gross power, lower peak cylinder pressures, and lower brake-specific fuel consumption were also observed. Gross power was increased by about 15--20% at base peak combustion pressure, and gross brake-specific fuel consumption was decreased by 2--10% with load. The effect of achieving oxygen enrichment by means of an air separation membrane is beyond the scope of the current study.

Response Surface Method Optimization of a High-Speed Direct-Injection Diesel Engine Equipped With a Common Rail Injection System

Abstract: To overcome the tradeoff between NO x and particulate emissions for future diesel vehicles and engines it is necessary to seek methods to lower pollutant emissions. The desired simultaneous improvement in fuel efficiency for future DI diesels is also a difficult challenge due to the combustion modifications that will be required to meet the exhaust emission mandates. This study demonstrates the emission reduction capability of EGR and other parameters on a high-speed direct-injection (HSDI) diesel engine equipped with a common rail injection system using an RSM optimization method. Engine testing was done at 1757 rev/min, 45% load. The variables used in the optimization process included injection pressure, boost pressure, injection timing, and EGR rate. RSM optimization led engine operating parameters to reach a low-temperature and premixed combustion regime called the MK combustion region, and resulted in simultaneous reductions in NO x and particulate emissions without sacrificing fuel efficiency. It was shown that RSM optimization is an effective and powerful tool for realizing the full advantages of the combined effects of combustion control techniques by optimizing their parameters. It was also shown that through a close observation of optimization processes, a more thorough understanding of HSDI diesel combustion can be provided.

Chaotic Combustion in Spark Ignition Engines

Abstract: We analyse the combustion process in a spark ignition engine using the experimental data of an internal pressure during the combustion process and show that the system can be driven to chaotic behaviour. Our conclusion is based on the observation of unperiodicity in the time series, suitable stroboscopic maps and a complex structure of a reconstructed strange attractor. This analysis can explain that in some circumstances the level of noise in spark ignition engines increases considerably due to nonlinear dynamics of a combustion process.

Knock Rating of Gaseous Fuels

Abstract: The knock tendency in spark ignition engines of binary mixtures of hydrogen, ethane, propane and n-butane is examined in a CFR engine for a range of mixture composition, compression ratio, spark timing, and equivalence ratio. It is shown that changes in the knock characteristics of binary mixtures of hydrogen with methane are sufficiently different from those of the binary mixtures of the other gaseous fuels with methane that renders the use of the methane number of limited utility. However, binary mixtures of n-butane with methane may offer a better alternative. Small changes in the concentration of butane produce almost linearly significant changes in both the values of the knock limited compression ratio for fixed spark timing and the knock limited spark timing for a fixed compression ratio.

A Refined Two-Zone Heat Release Model for Combustion Analysis in SI Engines

Abstract: A refined two-zone heat release model for combustion diagnostics in spark-ignition (SI) engines was developed and assessed. The novelty of the model includes the following improvements. A more general complex-variable formulation of Newton's convection law was applied for modeling the instantaneous surface-averaged heat flux so as to take the unsteadiness of gas-wall temperature difference into account. A CAD procedure was introduced to estimate the heat-transfer wall areas of the burned- and unburned-zone for assigned geometric features of the flame front. The energy conservation law was applied to the unburned-gas zone instead of the isentropic law that is commonly used to evaluate the temperature of the unburned gas. The calibration of the cumulative mass-fraction burned at the end of the flame propagation process was carried out through an overall energy balance of the whole cylinder charge during combustion. The unreleased energy predicted at the end of the flame propagation was related to the combustion efficiency stemming from the exhaust-gas composition. The new heat release model was shown to be an accurate means of combustion diagnostics for SI engines through its application to the analysis of combustion in a multivalve engine fueled by either natural gas or gasoline under a significant sample of operating conditions.

Sources and characteristics of oil consumption in a spark-ignition engine

Abstract: Engine oil consumption is an important source of hydrocarbon and particulate emissions in automotive engines. In addition, chemical compounds present in oil additives poison catalytic converters and reduce their conversion efficiency. As a part of the effort to comply with increasingly stringent emission standards, engine manufacturers strive to minimize engine oil consumption. This requires the advancement of the understanding of the characteristics, sources, and driving mechanisms of oil consumption. There is a general lack of oil consumption studies that connect comprehensive experiments and theoretical analysis. In this work, a combined theoretical and experimental approach was used to separate and quantify different oil consumption sources in a production spark ignition engine at different engine operating conditions. An extensive diagnostic system was successfully implemented on the test engine to measure real time oil consumption and in-cylinder parameters that affect major consumption sources such as inter-ring pressures, oil film thickness in the piston-ring-pack, and liner temperatures. A multi-species liner evaporation model was developed and verified by testing two oils with different volatility at varying cylinder liner temperatures and engine speed and load conditions. The experimental and modeling results were used to separate and quantify the contributions of oil evaporation, oil entrained in the blowby gas flow, and oil flow into the combustion chamber passing by the piston system to total engine oil consumption. The results show that the contribution of each consumption source varies with engine operating conditions. At low load, oil flowing past by the piston was found to be the major consumption source, while the contributions of oil evaporation and of blowby entrainment became more significant with increasing engine load. Furthermore, an extensive study was conducted to measure and analyze the oil consumption behavior during engine load transients to simulate real driving conditions. This work is an important step in advancing the understanding of oil consumption sources in spark ignition engines.

Nonperiodic Oscillations of Pressure in a Spark Ignition Engine

Abstract: We report our results on non-periodic experimental time series of pressure in a spark ignition engine. The experiments were performed for a low rotational velocity of a crankshaft and a relatively large spark advance angle. We show that the combustion process has many chaotic features. Surprisingly, the reconstructed attractor has a characteristic butterfly shape similar to a chaotic attractor of Lorentz type. The suitable recurrence plot shows that the dynamics of the combustion is a nonlinear multidimensional process mediated by stochastic noise.

Mathematical Modeling of Spark-Ignition Engine Cycles

Abstract: A quasi-dimensional spark-ignition (SI) engine cycle model has been developed. In this model, combustion is modeled as a turbulent flame propagation process. During the combustion, it is assumed that the cylinder charge consists of unburned and burned gas zones. A computer code was developed to present a mathematical cycle model. By using this code for any engine running at specified conditions, parameters that characterize the combustion, cycle, and engine performance can be computed practically. The above-mentioned parameters for several engines having different geometry and running at different operating conditions are determined theoretically, and these predicted values are compared to experimental data in the literature. Good agreement between predicted and experimental results were obtained. Comparisons of predicted and measured results show that the presented model is reliable for analyzing the SI engine cycles.

Hydrogen Fuelled Spark-Ignition Engines: Predictive and Experimental Performance

Abstract: Hydrogen is well recognized as a suitable fuel for spark-ignition engine applications that has many unique attractive features and limitations. It is a fuel that can continue potentially to meet the ever-increasingly stringent regulations for exhaust and greenhouse gas emissions. The application of hydrogen as an engine fuel has been tried over many decades by numerous investigators with varying degrees of success. However, the performance data reported often tend not to display consistent agreement between the various investigators, mainly because of the wide differences in engine type, size, operating conditions used, and the differing criteria employed to judge whether knock is taking place or not. With the ever-increasing interest in hydrogen as an engine fuel, there is a need to be able to model extensively various features of the performance of spark ignition (S.I.) hydrogen engines so as to investigate and compare reliably the performance of widely different engines under a wide variety of operating conditions. In the paper we employ a quasidimensional two-zone model for the operation of S.I. engines when fueled with hydrogen. In this approach, the engine combustion chamber at any instant of time during combustion is considered to be divided into two temporally varying zones: a burned zone and an unburned zone. The model incorporates a detailed chemical kinetic model scheme of 30 reaction steps and 12 species, to simulate the oxidation reactions of hydrogen in air. A knock prediction model, developed previously for S.I. methane-hydrogen fueled engine applications was extended to consider operation on hydrogen. The effects of changes in operating conditions, including a very wide range of variations in the equivalence ratio on the onset of knock and its intensity, combustion duration, power, efficiency, and operational limits were investigated. The results of this predictive approach were shown to validate well against the corresponding experimental results, obtained mostly in a variable compression ratio CFR engine. On this basis, the effects of changes in some of the key operational engine variables, such as compression ratio, intake temperature, and spark timing are presented and discussed. Some guidelines for superior knock-free operation of engines on hydrogen are also made.

Secondary Air Injection in the Exhaust After-Treatment System of S.I. Engines: 1D Fluid Dynamic Modeling and Experimental Investigation

Abstract: The paper describes the experimental and simulation work recently carried out to investigate the effects of secondary air injection on the emission conversion in the exhaust after-treatment system of a S.I. automotive engine. The modeling of the 1 D unsteady reacting flows in the complete exhaust system of a spark ignition engine, designed to satisfy the Euro IV limits, has been performed including the secondary air injection system, to predict the possible shortening of catalyst light-off time and the speed-up of the after-treatment system warm-up. The transport of chemical species with reactions in gas phase (post-oxidation of unburned HC in the exhaust manifold) and in solid phase (conversion of pollutants in the catalyst) with and without secondary air has been simulated by the 1D thermo-fluid dynamic model GASDYN, developed by the authors. The code has been extended to simulate the injection of air in the exhaust manifold and predict the consequent post-oxidation of pollutants in the ducts. The main chemical reactions arising in gas phase, in the upper part of the exhaust manifold, have been included, considering the oxidation of C 3 H 6 , C 3 H 8 and CO and the steam-reforming of C 3 H 6 and C 3 H 8 . The heat released in the gas due to the exothermal reactions has been taken into account, to evaluate the exhaust gas temperature along the ducts with injection of air. A Fiat-Alfa Romeo four-stroke, four-cylinder 2.0L automotive S.I. engine complying with the Euro IV regulations has been modeled, in order to predict the chemical specie concentration along the exhaust system. A large set of experimental data concerning this engine (cylinder pressure, pressure pulses, wall and gas temperatures, gas chemical composition along the system) with different secondary air mass flows has enabled a comprehensive comparison between predictions and measurements, in order to validate the model in different operating conditions.

Investigation of the detection of knock and misfire of a spark ignition engine with the ionic current method

Abstract: This paper reports an investigation of detection of knock and misfire in the spark ignition engine by means of the ionic current method. In the knock experiments, two detecting methods are ...

Manifold Gas Dynamics Modeling and Its Coupling With Single-Cylinder Engine Models Using Simulink

Abstract: A flexible model for computing one-dimensional, unsteady manifold gas dynamics in single-cylinder spark-ignition and diesel engines has been developed. The numerical method applies an explicit, finite volume formulation and a shock-capturing total variation diminishing scheme. The numerical model has been validated against the method of characteristics for valve flows without combustion prior to coupling with combustion engine simulations. The coupling of the gas-dynamics model with single-cylinder, spark-ignition and diesel engine modules is accomplished using the graphical MATLAB-SIMULINK environment. Comparisons between predictions of the coupled model and measurements shows good agreement for both spark ignition and diesel engines. Parametric studies demonstrating the effect of varying the intake runner length on the volumetric efficiency of a diesel engine illustrate the model use.