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Technical Paper

Monoglyceride Content in Marine Diesel Fuel-A Guide

Problems with the low-temperature operability performance of biodiesel in blends with petroleum diesel are infrequent, but continue to limit the use of biodiesel during winter months. A troubling aspect of this problem is that in some cases precipitates above the blend Cloud Point (CP) have been detected and have led to plugging of fuel filters and subsequent engine stalling, as well as plugging of fuel dispenser filters. Many researchers found that the saturated monoglyceride content was a main component of the material that was found on plugged fuel filters, as well as traces of Saturated DiGlycerides (SDG), were also present on the plugged fuel filters. This is the reason which forced the organization of standardization to suggest a procedure in order to predict the content of the Saturated MonoGlycerides (SMG) even with uncertainty which can vary from −50% to +50%. The model which was used will be the same as that which was introduced in the Annex C of EN 14214+A1:2013.
Technical Paper

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

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

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

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.
Technical Paper

An Integrated Transient Analysis Simulation Model Applied in Thermal Loading Calculations of an Air-Cooled Diesel Engine Under Variable Speed and Load Conditions

A comprehensive transient analysis simulation model is used for the calculation of diesel engine performance under variable speed and load conditions. The analysis includes a detailed description of engine subsystems under transient conditions, thus accounting for the continuously changing character of transient operation, simulating among others the fuel injection, transient mechanical friction, heat losses to the walls and governor operation. The results of engine performance, at every time step during the transient event, are used as inputs for the formulation of thermal boundary conditions, which are needed for the calculation in a parallel way of the thermal transients propagating inside the engine structure.
Technical Paper

A Simulation Analysis of the Effect of Governor Technical Characteristics and Type on the Transient Performance of a Naturally Aspirated IDI Diesel Engine

A transient analysis simulation program is developed for studying the response of an indirect injection, naturally aspirated, diesel engine after a rapid increase in load when this is equipped with various types of indirect acting governors. Analytical expressions are presented for the better simulation of engine mechanical friction, inertia moments and heat loss to the walls under transient conditions, governor dynamics for both the sensing element and the servopiston, soot emissions and the fuel pump operation. Various types of governor sensing elements (i.e. mechanical, electrical, two-pulse) and feedbacks (i.e. unity and vanishing) for the servomechanism are studied. Explicit diagrams are given to show how each combination of governor type and technical parameters (i.e. mass and number of flyweights, geometrical dimensions, amplification factors) affects the speed response as well as the speed droop and the recovery period of the particular engine.
Technical Paper

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

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

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

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

Development and Validation of a Detailed Fuel Injection System Simulation Model for Diesel Engines

The fuel injection system of diesel engines is of great importance since it controls the combustion mechanism. The rate of injection and the speed of injected fuel are important parameters for engine operation, controlling the combustion and pollutants formation mechanisms. A fuel injection system simulation capable of predicting the performance of the injection system to a good degree of accuracy has been developed. The simulation is based on a detailed geometrical description of the injection system and in modeling each subsystem as a separate control volume. The simulation starts at the driving mechanism of the fuel pump and describes all parts of the system pump chamber, delivery valve, delivery chamber, connecting pipe and injector. The components of the system are put together and interact as they do in reality. From the cam geometry an analytical expression is derived that gives the pump piston lift as a function of the engine crank angle.
Technical Paper

A Study on Microbial Contamination of Alcohol-Blended Unleaded Gasoline

The fuel supply chain faces challenges associated with microbial contamination symptoms. Microbial growth is an issue usually known to be associated with middle distillate fuels and biodiesel, however, incidents where microbial populations have been isolated from unleaded gasoline storage tanks have also been recently reported. Alcohols are employed as gasoline components and the use of these oxygenates is rising, especially ethanol, which can be a renewable alternative to gasoline, as well. Despite their alleged disinfectant properties, a number of field observations suggests that biodeterioration could be a potential issue in fuel systems handling ethanol-blended gasoline. For this reason, in this study, the effect of alcohols on microbial proliferation in unleaded gasoline fuel was assessed. Ethanol (EtOH), iso-propyl alcohol (IPA) and tert-butyl-alcohol (TBA) were evaluated as examples of alcohols utilized in gasoline as oxygenates.
Technical Paper

Particulate Contamination in Biodiesel Fuel under Long-Term Storage

Many incidents associated with filter plugging have extensively been reported in microbially contaminated diesel and biodiesel fuel systems, especially under long term storage conditions. In this study a quantitative assessment of the undesirable insoluble solids produced in contaminated biodiesel fuels was carried out in order to evaluate their evolution rate during biodeterioration. For this purpose, a series of contaminated biodiesel fuel microcosms were prepared and stored for six months under stable conditions. The quantity of the particulate contaminants was monitored during storage by a multiple filtration technique which was followed at the end by a comparison with the active bioburden per ATP bioluminescence protocol. Additionally, identical microcosms were treated with a commercially available biocide in order to examine the latter’s activity both on solids formation and the microbial proliferation.