CHAPTER ONE
INTRODUCTION
1.0 A Summary of the Study
The significance of this research cannot be over emphasized especially as it relates to examining the effects of intercooler refrigeration on marine diesel engine employed onboard large boats and vessels. There are three certain problems in automotive applications namely; environmental effect, cost and comfort problems. Therefore, internal combustion engines are required to have not only a high specific power output but also to release less pollutant emissions. For these reasons, current light and medium duty engines are being highly turbocharged because of having negative environmental effects of internal combustion engines. This study attempts to examine the performance characteristics of the internal combustion engine.
Performance figures are important – not only for the engine manufacturers, but also for the modeler, who wishes to find the best engine for his model. The problem often encountered is that most manufacturers only give a value for the maximum performance, but do not specify the conditions under which they have achieved this performance. In practice, it is observed that these performance figures cannot be obtained under normal operating conditions, probably due to noise reasons or due to a different fuel mixture or varying environmental conditions.
Existing literature regularly review model engines and often show performance figures and charts, but usually they do not describe, how these data were collected. This research examines and presents the methodology on how performance measurements can be carried out. The methods are simple and produce very accurate results. In addition, studies for supercharging systems are also included in this range. One of the most important problems faced in supercharging systems is that air density decreases while air is being compressed. Moreover, air with high temperature causes pre-ignition and detonation at spark ignited engines.
Various methods have been developed to cool down charge air which is heated during supercharging process. One of these methods is to use compact heat exchangers such as intercoolers to cool charging air. The purpose of an intercooler is to cool the charge air after it has been heated during turbocharging. As the air is cooled, it becomes denser; and denser air makes for better combustion, to produce more power. The denser air helps reduce the chances of knock. In this study, the intercooling concept was introduced and performance increase of a vehicle by adding intercooling process to a conventional supercharging system in diesel or petrol engine was analytically studied. Velocity of rotation and torque were used as input parameters to calculate the engine power output. It is found that the engine power output can be increased by ideal intercooler.
1.1 Introduction and Background of the Study
The low-speed two-stroke marine diesel engine is comprises of the fixed part, the moving part, the distribution system, the fuel system, the lubrication system, the cooling system, the starting system, the speed regulation device, the reversing arrangement, and the supercharging system. Because of its good power performance, the fuel efficiency and the reliability, the modern merchant ship takes it to directly drive the propeller as a main propulsion system. Its performance has decided the entire ship’s power performance and economic performance. Controlling the intake swirl intensity is the principal means to solve the fuel oil efficiency and the emission question under the diesel engine’s different speed condition.
The invariable intake swirl system is applied in the low speed diesel engine to study the oil atomization in the cylinder and the combustion process to the intake swirl intensity’s request under the different operating modes in order to realize the reasonable match of the intake swirl intensity with the fuel injection process. On the foundation of the twin inlet structure this report analyzed, the intake swirl control area and its influence to the gas charging efficiency proposed the design scheme for the invariable intake swirl control system. By matching reasonably the intake, the exhaust, and the injection process of the diesel engine, the combustion process is further optimized to satisfy the target request for the complete machine’s power, fuel oil efficiency and emission. For the marine diesel engine, the fuel economy is one essential index.
Currently, using the electronically controlled fuel injection system with the common rail and the variable intake swirl control system to optimize the cylinder combustion process, the engine achieves the minimum fuel consumption close to 170g/kWh. Improving the cylinder combustion process has no significant potential to reduce the fuel consumption. The power consumption of the engine’s cooling system accounts for about 5% of the overall engine’s power, so improving the whole economy has enormous potential. Controlling the heat dissipation capacity of the cooling process at the different heat conditions to achieve the optimum combustion chamber temperature can not only improve the reliability, but also reduce the heat loss of the burning process and improve the thermal efficiency.
Reducing the water flow of the cooling pump in the partial load can lower the mechanical power loss of the cooling system to improve the whole economy. To achieve the reasonable match of the cooling system with the whole engine, the working process of the low-speed diesel engine is analyzed to determine the optimum heat dissipation required for the different conditions. The cooling system is designed, and the heat dissipation potential of the cooling system is analyzed in the different temperature and flow conditions to match reasonably the cooling system with the whole engine.
Internal combustion engines (ICE) play a major role in our lives. With respect to the various predictions, conventional internal combustion engines can be used around 10-30 years. This period is one fourth of an internal combustion engine’s age. It means that their total environmental effects will have been multiplied approximately with 1.25 in this period. Also, hybrid vehicles, which will be alternatively used after conventional vehicles would be down, will use instead of lonely used internal combustion engines. These facts show that internal combustion engines should be optimized to lower their environmental effects.
Today, as known, 70% of carbon monoxide, 50% of nitrogen oxide and 42% of volatile organic compounds (hydro carbons) are originating from internal combustion engines [1].
