Description
ABSTRACT
A direct injection (OI) and an indirect injection (IDI) diesel engine have been used to study the effect of engine type on soot and unburnt liquid hydrocarbons contained in diesel exhausts as a function of the air/fuel mass ratio, α. The impact of the broadening fuel specifications on diesel emissions has been investigated for both engines burning four different fuels in order to provide a relationship between fuel and particulate composition.
Soot and liquid hydrocarbon emissions seem to be affected by the fuel aromatic content and volatility in a different way in the two engine types in dependence on the air/fuel ratio.
In the D1 engine soot decreases as α increases, while liquid hydrocarbons show an opposite trend. In this engine a lower cetane number and a higher fuel volatility result in decreased soot emission since a higher amount of fuel can burn in “lean”. premixed conditions, avoiding soot formation. Thus the enhancing effect of aromatic content on soot formation is masked by the corresponding decrease of the fuel cetane number. Unburnt liquid hydrocarbon emissions increase as the fuel volatility decreases and, for the fuels having the same volatility, just a slight enhancing effect of aromatic content was found.
In the ID1 engine soot and liquid hydrocarbons decrease as α increases. The fuel injected can mix only with the available air in the prechamber leading to a very “rich” premixed region where partially pyrolyzed compounds and soot are massively formed independently on the fuel cetane number. In this engine either the fuel aromatic content or volatility increase promote soot and liquid hydrocarbon emissions.
Keywords
Soot, Combustion, Fuel, Exhaus
TABLE OF CONTENTS
COVER PAGE
TITLE PAGE
APPROVAL PAGE
DEDICATION
ACKNOWELDGEMENT
ABSTRACT
CHAPTER ONE
- INTRODUCTION
- BACKGROUND OF THE STUDY
- PROBLEM STATEMENT
CHAPTER TWO
LITERATURE REVIEW
- INTERNAL COMBUSTION
- COMBUSTION
- SHIP INTERNAL COMBUSTION ENGINES
- FUELS AND CYLINDER LUBRICATING OILS
- FUEL QUALITY (HIGH SULPHUR AND LOW SULPHUR FUEL OIL
- HC (HYDROCARBON)
- PARTICULAR MATTER
- SOOT FORMATION
- FUELS AND CYLINDER LUBRICATING OILS
- EXHAUST OUTPUTS
- CARBON
- HYDROGEN
- NITROGEN OXIDE
- SULPHUR OXIDE
- EXHAUST EMISSION AND POLLUTION
- INTERNATIONAL REGULATIONS ON POLLUTION
- EMISSION CONTROL AREA
- SOOT COLLECTION AND STORAGE
CHAPTER THREE
METHODOLOGY
3.1 EXPERIMENTAL APPARATUS
3.2` TEST PROCEDURES
CHAPTER FOUR
- RESULTS AND DISCUSSION
CHAPTER FIVE
- CONCLUSION
- RECOMMENDATION
- REFERENCES
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND
An internal combustion engine (ICE) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is applied typically to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into useful work.
The first commercially successful internal combustion engine was created by Étienne Lenoir around 1860[1] and the first modern internal combustion engine was created in 1876 by Nicolaus Otto (see Otto engine).
The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar four-stroke and two-stroke piston engines, along with variants, such as the six-stroke piston engine and the Wankel rotary engine. A second class of internal combustion engines use continuous combustion: gas turbines, jet engines and most rocket engines, each of which are internal combustion engines on the same principle as previously described.[1][2] Firearms are also a form of internal combustion engine.[2]
In contrast, in external combustion engines, such as steam or Stirling engines, energy is delivered to a working fluid not consisting of, mixed with, or contaminated by combustion products. Working fluids can be air, hot water, pressurized water or even liquid sodium, heated in a boiler. ICEs are usually powered by energy-dense fuels such as gasoline or diesel fuel, liquids derived from fossil fuels. While there are many stationary applications, most ICEs are used in mobile applications and are the dominant power supply for vehicles such as cars, aircraft, and boats.
Typically an ICE is fed with fossil fuels like natural gas or petroleum products such as gasoline, diesel fuel or fuel oil. There is a growing usage of renewable fuels like biodiesel for CI (compression ignition) engines and bioethanol or methanol for SI (spark ignition) engines. Hydrogen is sometimes used, and can be obtained from either fossil fuels or renewable energy.
‘‘Soot’’ has been one of the most frequently studied and enduring topics in the combustion research community. Its formation in engines contributes to component fouling and efficiency losses by radiative heat transfer, while its emission negatively impacts human health and the environment. In the early 1970s, a number of fundamental studies on soot formation and oxidation processes by means of shock-tube and flat flame burner experiments have been reported. The results obtained in these studies are the root of our understanding of the soot processes in internal combustion engines.
1.2 STATEMENT OF PROBLEM
Minimizing soot emissions from diesel engines has been perpetual target as the level of engine-out soot emission limits the maximum engine torque. In the old days, when fuel injection systems relied on a mechanical pump, the injection pressure depended on the engine speed. This resulted in higher smoke emissions at low engine speed and high torque conditions due to the lower injection pressure and lower swirl velocity.
The above problem was solved in the late 1990s by the common-rail fuel injection system, which allows the fuel injection pressure to be decoupled from the engine speed. The advancement provided arbitrary control of both the injection pressure and phasing. Combining the multiple injection strategies enabled by the common-rail system with variable geometry turbo-charging, diesel combustion technology attained revolutionary progress.
However, internal combustion engines are still subject to increasingly strict demands for reduced carbon dioxide, nitrogen oxides (NOx) and particulate matter (PM) emissions. Indeed, meeting the stringent global emissions standards has required the addition of exhaust after-treatment systems to both gasoline and diesel engines. The diesel particulate filter (DPF) is an effective device to trap soot particles thereby removing more than 99% of the engine-out particle mass. The soot accumulated in the DPF after a certain driving distance must be burned off—a process referred to as regeneration. The regeneration process depends on the exhaust flow rate, oxygen concentration, temperature and soot mass loading on the DPF. Optimization of the regeneration strategy requires a deep understanding of the mechanism by which soot deposited on the filter oxidizes. Although the DPF can remove soot particles in the exhaust with a high-trapping efficiency, strategies to further reduce soot emissions from the cylinder are still warranted as the increased pressure drop in the DPF deteriorates engine performance and frequent regeneration constitutes a significant fuel penalty.
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 INTERNAL COMBUSTION
Combustion, also known as burning, is the basic chemical process of releasing energy from a fuel and air mixture. In an internal combustion engine (ICE), the ignition and combustion of the fuel occurs within the engine itself. The engine then partially converts the energy from the combustion to work. The engine consists of a fixed cylinder and a moving piston. The expanding combustion gases push the piston, which in turn rotates the crankshaft. Ultimately, through a system of gears in the power train, this motion drives the vehicle’s wheels.
There are two kinds of internal combustion…
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