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Technical Paper

Using Advanced Injection Timing and EGR to Improve DI Diesel Engine Efficiency at Acceptable NO and Soot Levels

2001-03-05
2001-01-0199
The direct injection diesel engine is one of the most efficient thermal engines known to man. For this reason DI diesel engines are widely used for heavy-duty applications and especially for the propulsion of trucks. Even though the efficiency of these engines is currently at a high level there still exist possibilities for further improvement. One way to accomplish this is by increasing the injection timing which usually improves, depending on the operating conditions, the indicated efficiency of the engine. On the other hand advanced injection timing has a negative effect on peak pressure causing a serious increase of its value, a negative effect on NO emissions which are also seriously increased and a positive effect on Soot emissions which are reduced. In the present work a theoretical and experimental investigation is presented to determine the effect of more advanced injection timing on engine performance and pollutant emissions.
Technical Paper

Use of JP-8 Aviation Fuel and Biodiesel on a Diesel Engine

2004-10-25
2004-01-3033
The present paper aims to discuss the quality characteristics of Jet Fuels used in the Greek market in comparison with fuels used in other countries and to evaluate jet fuels along with diesel and biodiesel on a diesel engine. To establish the quality characteristics for Jet Fuels of the Greek market, fuel samples were collected from the local refineries on a regular basis, thus monitoring the fuel quality fluctuation over time. JP8, along with diesel and biodiesel, were used alone and in mixtures on a single cylinder stationary diesel engine. Emissions and volumetric fuel consumption were measured under various loads.
Technical Paper

The Effect of Various Dynamic, Thermodynamic and Design Parameters on the Performance of a Turbocharged Diesel Engine Operating under Transient Load Conditions

2004-03-08
2004-01-0926
Thermodynamic, dynamic and design parameters have a significant and often conflicting impact on the transient response of a compression ignition engine. Knowing the contribution of each parameter on transient operation could direct the designer to the appropriate measures for better engine performance. To this aim an explicit simulation program developed is used to study the performance of a turbocharged diesel engine operating under transient load conditions. The simulation developed, based on the filling and emptying approach, provides various innovations as follows: Detailed analysis of thermodynamic and dynamic differential equations, on a degree crank angle basis, accounting for the continuously changing nature of transient operation, analysis of transient mechanical friction, and also a detailed mathematical simulation of the fuel pump. Each equation in the model is solved separately for every cylinder of the 6-cylinder diesel engine considered.
Technical Paper

The Effect of EGR on the Performance and Pollutant Emissions of Heavy Duty Diesel Engines Using Constant and Variable AFR

2001-03-05
2001-01-0198
Pollutant emissions and specifically NO and soot are one of the most important problems that engineers have to face when developing heavy duty DI diesel engines. Two main strategies exist as options for their control, reduction inside the engine cylinder using advanced combustion and fuel injection technologies and use of after-treatment systems. In the present work it is examined the use of EGR to control the formation of NO inside the cylinder of an engine with extremely high peak pressure. The work is applied on a single cylinder truck test engine developed under a project funded by the European Community focusing on the improvement of heavy duty DI diesel engine efficiency using increased injection timing. Use is made of a simulation model to predict the effect of more advanced injection timing on engine performance and emissions. The model has been modified to include the effect of EGR used to c ontrol the formation of NO which is considerably increased at high injection timings.
Technical Paper

Study of the Transient Behavior of Turbocharged Diesel Engines Including Compressor Surging Using a Linearized Quasi-Steady Analysis

2005-04-11
2005-01-0225
The transient operation of turbocharged diesel engines during turbocharger compressor surging is investigated through simulation. This form of compressor dynamic instability can generate large amplitude compressor mass flow and pressure rise oscillations, sometimes leading even to flow reversals, and may also induce severe torsional loading to the turbocharger shaft. A model predicting the dynamic behavior of the engine air-charging system when compressor surging occurs was developed in conjunction with a linearized quasi-steady diesel engine simulation code. This analysis possesses the advantage over the more detailed engine codes of basic simplicity, speed of calculation and no need of many engine and turbocharger components parameters given as input data. Emphasis is given to the correct modeling of the physics of the phenomena concerned. Transient operation runs, including critical cases for surging initiation, were applied for two similar six-cylinder diesel engines.
Technical Paper

Structure of high-pressure diesel sprays

2001-09-23
2001-24-0009
A comprehensive set of computational and experimental results for high- pressure diesel sprays are presented and discussed. The test cases investigated include injection of diesel into air under both atmospheric and high pressure/temperature chamber conditions, injection against pressurized and cross-flowing CF6 simulating respectively the density and flow conditions of a diesel engine at the time of injection, as well as injection into the piston bowl of both research and production turbocharged high-speed DI diesel engines. A variety of high-pressure injection systems and injector nozzles have been used including mechanical and electronic high-pressure pumps as well as common-rail systems connected to nozzles incorporating a varying number of holes with diameters ranging from conventional to micro-size.
Technical Paper

Some Considerations on the Estimation of the Heat Release of DI Diesel Engines Using Modelling Techniques

2004-03-08
2004-01-1405
Simulation models are widely used from research engineers to investigate the combustion mechanism of DI diesel engines. These models can be used, as tools to either comprehend information provided by experimental data or to perform predictions and assist the development process. As widely recognized a valuable source of information for engine performance and emissions studies is the cylinder pressure trace. It can provide after processing information concerning the combustion rate of fuel injected inside the combustion chamber. Often it is also used to calibrate simulation models or even to derive correlations to represent the combustion rate of fuel inside the combustion chamber. The present research team has during the development process of a simulation model for the description of DI diesel engine performance and emissions realized that there exists a serious problem.
Technical Paper

Single Fuel Research Program Comparative Results of the Use of JP-8 Aviation Fuel versus Diesel Fuel on a Direct Injection and Indirect Injection Diesel Engine

2006-04-03
2006-01-1673
During the last years a great effort has been made by many NATO nations to move towards the use of one military fuel for all the land-based military aircraft, vehicles and equipment employed on the military arena. This idea is known to as the Single Fuel Concept (SFC). The fuel selected for the idea of SFC is the JP-8 (F-34) military aviation fuel which is based upon the civil jet fuel F-35 (Jet A-1) with the inclusion of military additives possessing anti-icing and lubricating properties. An extended experimental investigation has been conducted in the laboratory of Thermodynamic and Propulsion Systems at the Hellenic Air Force Academy. This investigation was conducted with the collaboration of the respective laboratories of National Technical University of Athens and Hellenic Naval Academy as well.
Technical Paper

Sensitivity Analysis of Multi-Zone Modeling for Combustion and Emissions Formation in Diesel Engines

2006-04-03
2006-01-1383
In the present work a sensitivity analysis is conducted using a multi-zone phenomenological model developed in the past by the author's, to estimate the effect of model's constants on engine performance and emissions. The constants used for this analysis are those embedded in the semi-empirical relations of the model, regarding air entrainment rate, combustion rate, ignition delay and evaporation rate. The model is applied on a heavy duty supercharged DI diesel engine and the effect of each of these constants on measurable engine parameters is defined. From the sensitivity analysis the relation between model constants and engine output data is derived. These results are used to define a constants determination procedure. The target is to define a limited number of adjustable constants so that the procedure can be of practical use. Following this, the calibration procedure is applied to determine the value of each constant, at various engine speeds and loads for the engine in question.
Technical Paper

Second-Law Analysis of Indirect Injection Turbocharged Diesel Engine Operation under Steady-State and Transient Conditions

2005-04-11
2005-01-1131
A second-law analysis is performed in both chambers of an indirect injection turbocharged diesel engine and the simulation program developed is used to study the second-law performance of the engine at various operating conditions, steady state and transient. The simulation developed is based on the filling and emptying approach and provides detailed analysis of thermodynamic, dynamic and second-law differential equations on a degree crank angle basis. It incorporates a detailed mathematical simulation of the fuel pump and solves each equation separately for each one of the six cylinders of the engine in hand. The model is validated against experimental data at steady state and transient conditions, obtained at the authors' laboratory. The prechamber rate and cumulative availability terms and irreversibilities are computed and depicted against the main chamber ones during the 720 degrees crank angle of an engine cycle.
Journal Article

Regulated and Unregulated Emissions of a Euro 4 SUV Operated with Diesel and Soy-based Biodiesel Blends

2009-11-02
2009-01-2690
In this study, regulated, unregulated exhaust emissions and fuel consumption with ultra low sulphur diesel and soy-based biodiesel blends at proportions of 10 and 30% v/v have been investigated. A Euro 4 compliant SUV, equipped with a 2.2 litre common-rail diesel engine and an oxidation catalyst was tested on a chassis dynamometer with constant volume sampling (CVS) technique. Emission and fuel consumption measurements were performed over the New European Driving Cycle (NEDC) and the non-legislated Artemis driving cycles which simulate urban, rural, and highway driving conditions in Europe. The regulated pollutants were characterized by determined NOx, PM, CO, and HC. CO2 was also quantified in the exhaust. Overall, 16 PAHs, 4 nitro-PAHs, 6 oxy-PAHs, 13 carbonyl compounds and particulate alkanes ranged from C13 to C35 were determined in the exhaust.
Journal Article

Possibility to Determine Diesel Engine Condition and Tuning from the Application of a Diagnostic Technique at a Single Operating Point

2009-04-20
2009-01-0681
A difficulty which exists when applying diagnostic techniques on large-scale diesel engines operating on the field, is that usually it is not possible to obtain measurement data at a wide engine operating range due to a number of constraints. In the present work is investigated the possibility to overcome this practical difficulty originating from the test procedure for engines operating on the field (i.e. marine or stationary applications). The main objective is to examine if a diagnosis procedure provides similar results when applied at various engine operating conditions. For this purpose an existing diagnostic technique, developed by the authors, is applied at different operating conditions on a large-scale two-stroke diesel engine used for power generation in a Greek island.
Technical Paper

Parametric Study of the Availability Balance in an Internal Combustion Engine Cylinder

2001-03-05
2001-01-1263
The current work uses a method developed by the authors for both combustion irreversibility and working medium availability computations in a high speed, naturally aspirated, four stroke, internal combustion engine cylinder. The objective of the study was to extrapolate already published results of the second-law analysis of diesel engine operation by studying parametrically the effect of main operating parameters such as engine speed of rotation, injection timing, and fuel composition. Extensive experimental data were available for the case of dodecane injection, which were used for the determination of the fuel reaction rate. Computationally, the same reaction rates were used for methane and methanol injection. The production rate of irreversibility during combustion was analytically calculated as a function of the fuel reaction rate with the combined use of first and second-law arguments and a chemical equilibrium hypothesis.
Technical Paper

Multi-Zone Combustion Modelling for the Prediction of Pollutants Emissions and Performance of DI Diesel Engines

1997-02-24
970635
In the past years various models have been proposed for the modelling of performance and pollutants emissions from DI diesel engines. These models range from complicated 3D detailed ones up to simple two zone phenomenological ones. The latter ones although simple offer solutions in engine study and are widely used due to their low computational cost and simplicity. In the present work a multi-zone model for direct injection diesel engines is presented together with its application on a direct injection diesel engine located at the authors laboratory. Multi-zone models usually fail to predict adequately both pollutants emissions and performance and thus focus mainly on pollutants emissions. Of course this is not acceptable since the formation of pollutants is strongly related to the combustion mechanism. In the present work an effort has been made to overcome this problem and predict both performance and emissions throughout the engine operating range.
Technical Paper

Modeling the Effects of EGR on a Heavy Duty DI Diesel Engine Using a new Quasi-Dimensional Combustion Model

2005-04-11
2005-01-1125
The model has already been applied on an old technology, naturally aspirated HSDI Diesel engine and on a heavy-duty turbocharged DI one equipped with a high pressure PLN fuel injection system, and the results were satisfying as far as performance and pollutant emissions (Soot and NO) are concerned. Taking into account that the main scope of engine simulation models is to assist engineers and researchers to understand the complex mechanisms involved in diesel engine combustion and pollutants formation and that through the continues engine development, new techniques are implemented, it is obvious that engine simulation models must always be enhanced with new features in order to be kept up-to-date. In this study the model has been modified to take into account the effect of EGR, since the latter one is a measure that will be used more extensively in the future to control NO emissions from turbocharged HDDI Diesel engines.
Technical Paper

Identification of a Robotic Arm Using Optimization Methods for Model Estimation

2002-07-09
2002-01-2047
The system identification procedure is a powerful and flexible tool for the modeling of dynamic systems. This paper implements the theory of parametric identification in order to estimate a valid model of a flexible robotic arm. For this purpose experimental data is used for the estimation of ARMAX SISO models. A two-stages identification procedure (non-parametric & parametric) provides an insight about the system under identification. In the first stage, known signal analysis methods are applied (correlation-spectral analysis) for the estimation of frequencies and frequency response, and in the second stage, the estimation of ARMAX models is performed in order to fit a transfer function model to collected input-output data set. For the estimation of model's coefficients, use of Evolutionary Algorithms is implemented.
Technical Paper

Identification and Correction of the Error Induced by the Sampling Method Used to Monitor Cylinder Pressure of Reciprocating Internal Combustion Engines

2012-04-16
2012-01-1155
Cylinder pressure measurements are common practice for internal combustion reciprocating engines during field or lab applications for the purpose of combustion analysis, condition monitoring etc. The most accurate method is to measure cylinder pressure using a crank angle encoder as a trigger source to guarantee cylinder pressure measurement at predefined crank angle events. This solution, even though favorable, presents a number of practical difficulties for field applications and increased cost, for this reason its use is practically restricted to lab applications. Therefore a commonly used approach for ad hoc measurements is to digitize samples at fixed time intervals and then convert time into crank angle assuming a constant rotational speed. But if engine rotational speed is not constant within the engine cycle this may result to incorrect cylinder pressure CA referencing.
Technical Paper

Experimental Investigation on the Stabilizing Effect of n-Butanol on Diesel-Bioethanol Blends

2018-09-10
2018-01-1744
In accordance to the current environmental policy of the European Union by 2020, 10% of the transport fuel in every country comes from renewable sources such as biofuels. One of the most popular biofuels, (bio) ethanol is a probable suitable candidate for addition in diesel fuel because of its cleaner combustion and the ability to reduce emissions of gaseous pollutants. However, its use presents some important problems, attributed mainly to its incompatibility with diesel fuel during mixing due to the difference in the polarity. For this reason, substances that act as stabilizers of these mixtures are used, one of the most suitable being butanol. This substance is compatible with diesel fuel and ethanol, acting as a chemical bridge between the two, but also exhibits positive combustion behavior, as it is also an oxygenate that can be produced from renewable sources as well. The aim of this work was to investigate the behavior of diesel-ethanol mixtures using butanol as co-solvent.
Technical Paper

Experimental Investigation of the Effect of Fuel Composition on the Formation of Pollutants in Direct Injection Diesel Engines

1999-03-01
1999-01-0189
A great deal of research is taking place at the present time in the field of diesel engines, especially regarding the emission of gaseous pollutants and soot. This research is essential for engine manufacturers since it is difficult for diesel engines to meet current standards regarding soot and nitric oxide emissions. The problem will become even more severe when the new legislation will be applicable requiring a 50% reduction of existing levels. Many manufacturers and researchers feel that engines will be difficult to meet this criterion without the use of other techniques such as gas aftertreatment or newly developed fuels (low sulfur content, etc.). The aim of this research is to examine the effect of fuel composition and physical properties on the mechanism of combustion and pollutants formation.
Technical Paper

Experimental Investigation of Instantaneous Cyclic Heat Transfer in the Combustion Chamber and Exhaust Manifold of a DI Diesel Engine under Transient Operating Conditions

2009-04-20
2009-01-1122
In this paper, the results are presented from the analysis of the second stage of an experimental investigation with the aim to provide insight to the cyclic, instantaneous heat transfer phenomena occurring in both the cylinder head and exhaust manifold wall surfaces of a direct injection (DI), air-cooled diesel engine. Results from the first stage of the investigation concerning steady-state engine operation have already been presented by the authors in this series. In this second stage, the mechanism of cyclic heat transfer was investigated during engine transient events, viz. after a sudden change in engine speed and/or load, both for the combustion chamber and exhaust manifold surfaces. The modified experimental installation allowed both long- and short-term signal types to be recorded on a common time reference base during the transient event.
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