Compare Various Aspects of Gasoline Engine relative to Diesel Engine (Term Paper Sample)

Gasoline Engine verses Diesel Engine
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Introduction
The term ‘engine’ was derived from a Latine word ingenium, which means mechanical device, which converts force into a state of motion (Taylor, 1985). Most mechanica devices are said to have been invented during the period of industrial revolution. In the modern context, the term is used to refer to devices such as internal combustion engines, external combustion engines, air-breathing combustion engines and steam engines, which burn fuel to perform a mechanical work that generates electricity, compresses gas, or pumps water, among others. By use, main examples of engines include model engine, automobile engine, aircraft engine, motorcycle engine, marine propulsion engines, non-road engine, railway locomotive engine, traction engine, and spacecraft propulsion engine. The speed of engines is measured in terms of revolutions per minute. Therefore, engines are sometimes classified as high-speed, medium speed, or low-speed.
Definition of gasoline and diesel
Gasoline can be described as a crude oil product that can be used to power internal combustion. Experts assert that the liquid is transparent and highly flammable and usually tend to evaporate considerably when used. Gasoline comprises primarily of organic compounds that are derived from the fractional distillation of petroleum (Gupta & Demirbas, 2010). It is, however, enhanced with an array of additives such as ethanol when processed in an oil refinery to improve its stability and performance. Its quality is measure by its octane rating.
A diesel is defined as a light distillate fuel with a distillation temperature of about 550 degrees Fahrenheit. The liquid is largely used in high-speed diesel engines. It is, ideally, a mixture of hydrocarbons that are obtained during the fractional distillation of crude oil (Gupta & Demirbas, 2010). The key properties of diesel fuel include cold behavior, sulfur content, and a cetane number.
History of Diesel and Gasoline engines
History is an interest subject. This is largely because; it tends to give us a precise insight of how things happened in the past paving way for our understanding of the present and the future. In this section, we will tend to provide a critical review of the history of engines; stressing largely on diesel and gasoline engines.
Diesel engine
The first diesel engine was built in 1882 by the German engineer, Herbert Akroyd Stuart (Eastwood, 2008). He first perceived powdered coal as a potential fuel, although he later proved it to be arguably difficult to inject of a cylinder. After the fail of the coal experiment, he ventured into an experiment of using vegetable oils where he successfully used peanut oil. However, later, the engine settled on a stable byproduct of crude oil refinement process known as diesel fuel, hence the term diesel engine. Following the success of the diesel engine, Herbert filed a number of addenda and patents for the production of diesel engines in various countries in 1894 and 1895. These include patent no. 16654 (Spain), No. 243531 (France), No. 113139 (Belgium), No. 608845 (United States), and 86633 (Germany).
With the introduction of government regulation on diesel omissions, the original diesel engine has undergone a tremendous modification over the past, particularly in 1960 when manufactures began to redesign their engine products so that they can make them cleaner. These resulted to a number of innovations such as injection-timing delay and cooled exhaust gas re-circulation, which have trimmed down the rate of emissions from diesel engines by about 80 and 90% since 1980s.
Gasoline Engine
The invention of the gasoline (petrol) engine can be traced back to 1863, in France, when Jean Joseph Etienne Lenior fitted a petrol fuelled internal combustion engine earlier built in 1862 to an experimental three-wheeled wagon (Eastwood, 2008). His engine was a success, which helped him to make a number of journeys around Paris. Seven years later, the German-Austrian inventor known as Siegfried Marcus tested and assembled an experimental four-wheeled motorized cart that was using petrol engine. However, since the vehicle lacked a clutch, the rear wheels were often lifted before the petrol engine was started. Seven years later, again, a petrol engine car was designed in the United States by George Baldwin Selden designed the first car in America that was to be fitted with internal combustion engine power by petrol fuel. This was followed by a number of innovations such as exhaust muffler, and pistons with rings, among others.
How engines work
Irrespective of the type of engine, the mechanism with which engines work is primarily the same. Most engines works through a spark-ignition stroke; four stroke spark-ignition mechanism. Experts agree that the four stroke spark-ignition engine needs four piston strokes to complete one cycle. These have been discussed below.
Induction stroke
Here, the inlet valve is always opened as the exhaust value remains closed. Thereafter, the piston then descends by moving away from the cylinder. Its speed then creates a pressure decline or depression that reaches a maximum of approximately 0.3 bar below the atmospheric pressure; one-third from the beginning pressure value. However, the depression created may vary considerably depending on the load and speed experience by the engine. The creation of a depression is said to induce or suck in a fresh charge air coupled by the atomized fuel proportions that ranges from 10 to 17 parts of air to about 1 part of fuel by weight. The engines at this process are said to be ‘naturally aspirated’ or ‘normally aspirated’(Vidler &Knowles,, 2004).
Compression stroke
At this stage, both the exhaust and inlet valves are closed. This makes the piston to start ascending towards the cylinder head. During this time, the fuel charge and induce air charge are progressively compressed to something that occupies approximately 0.125 to 0.1 of the volume of the cylinder at inner post position of the cylinder. The compression squeezes the atomized-fuel and air molecules closer together cause a rise in both temperature and charge in the cylinder. Typically, the maximum compression in the cylinder ranges from 8 to 14 bar.
Power stroke
In the next piston stroke, the power stroke, both the exhaust and inlet values still remain closed, and just before the piston reach the climax of its stroke during the compression, research indicates that a spark-plug arguably ignites dense combustible charge. As the piston reaches its innermost stroke point, the charge mixture in the cylinder starts to burn, and thus generating heat and vastly increasing the pressure in the cylinder up to the point when the gas forces become greater than the load. The burning of gases are said to expand during the process and consequently changing the direction of motion, pushing it to its outermost point. Then, the cylinder pressure falls from a peak value of approximately 60 bar to about 4 bar close to the outermost movement of the piston.
Exhaust stroke
At the end of the third stroke, the inlet valve still remains closed. However, the exhaust value is opened. This makes the piston to change the direction of motion; moves to the innermost position from the outmost. At this time, most of the burnt gases are then expelled from the cylinder by the prevailing pressure energy of the gas. Although, the remaining piston still pushed the last of the spent gases in the cylinder out through the exhaust-valve port to the atmosphere. During this process, it is argued that the pressure of the gas in the cylinder often falls from the exhaust-valve opening pressure to the atmospheric pressure or less (Vidler &Knowles,, 2004). At this time, the piston usually nears the innermost part towards the head of the cylinder.
Advantages and disadvantages of various engine types
There are a number of advantages and disadvantages that can be attributed to each of the engine types discussed in the previous section. Some of them have been highlighted below.
Advantages and Disadvantages of Diesel Engine
There are number advantages that can be attributed to the use of diesel engine. First, most diesel engines are relative less costly as compared to petrol engines. Evidence indicates that the cost difference between diesel and petrol engines is about 20% level. In addition, diesel engines burn less fuel than petrol engines. This is because of ...