Internal Combustion Engine Fundamentals Pdf
Emelia Lute
Internal combustion engines provide outstanding drivability and durability, with more than 250 million highway transportation vehicles in the United States relying on them. Along with gasoline or diesel, they can also utilize renewable or alternative fuels (e.g., natural gas, propane, biodiesel, or ethanol). They can also be combined with hybrid electric powertrains to increase fuel economy or plug-in hybrid electric systems to extend the range of hybrid electric vehicles.
There are two kinds of internal combustion engines currently in production: the spark ignition gasoline engine and the compression ignition diesel engine. Most of these are four-stroke cycle engines, meaning four piston strokes are needed to complete a cycle. The cycle includes four distinct processes: intake, compression, combustion and power stroke, and exhaust.
Spark ignition gasoline and compression ignition diesel engines differ in how they supply and ignite the fuel. In a spark ignition engine, the fuel is mixed with air and then inducted into the cylinder during the intake process. After the piston compresses the fuel-air mixture, the spark ignites it, causing combustion. The expansion of the combustion gases pushes the piston during the power stroke. In a diesel engine, only air is inducted into the engine and then compressed. Diesel engines then spray the fuel into the hot compressed air at a suitable, measured rate, causing it to ignite.
Over the last 30 years, research and development has helped manufacturers reduce ICE emissions of criteria pollutants, such as nitrogen oxides (NOx) and particulate matter (PM) by more than 99% to comply with EPA emissions standards. Research has also led to improvements in ICE performance (horsepower and 0-60 mph acceleration time) and efficiency, helping manufacturers maintain or increase fuel economy.
Various projections for the US suggest that by 2030, some 10% to 25% of vehicles might be electrified. The question then remains, what about the other 90% to 75%? And what about the large trucks and ships that run on diesel fuel? There are, as yet, no convincing electric options for those vehicles. That is why it is still so important to continue working on internal combustion engines and make them as clean and efficient as we can.
Engine Fundamentals: Internal Combustion introduces learners to the basic components, concepts, and general terminology often associated with automotive engines. The various systems critical to the internal combustion process are brought to life in this course using realistic 3D models, helpful animations, and interactive quizzes. The material in this course is beneficial for both those who are experienced and practiced in automotive engines and related concepts, and those who are new to the field.
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The ideal combustion temperature for an IC engine varies depending on the type of fuel used and the design of the engine. Generally, it is around 2000-2500 degrees Fahrenheit for gasoline engines and 2200-2700 degrees Fahrenheit for diesel engines.
The combustion temperature in an IC engine can be affected by several factors, including the type of fuel used, the air-to-fuel ratio, engine design and tuning, and the efficiency of the cooling system.
Controlling the combustion temperature in an IC engine is crucial for maintaining the engine's performance, efficiency, and longevity. If the temperature is too low, the fuel may not completely burn, leading to decreased power and increased emissions. If the temperature is too high, it can cause engine damage and premature wear.
The combustion temperature in an IC engine is typically measured using a thermocouple, which is a type of temperature sensor that can withstand high temperatures. The sensor is placed in the combustion chamber to measure the temperature during the combustion process.
In internal combustion (IC) engines, the working fluid consists of air, a fuel-air mixture or the products of combustion of the fuel-air mixture itself. Reciprocating piston engines are perhaps the most common form of internal combustion engine known. They power cars, trucks, trains and most marine vessels. They are also used in many small utility applications. They can be fueled with liquid fuels such as gasoline and diesel fuel or gaseous fuels such as natural gas and LPG. Two common sub categories of reciprocating piston engines are the two-stroke and the four-stroke engine. Examples of rotary internal combustion engines include the Wankel rotary engine and the gas turbine.
Conventionally, spark-ignited systems are characterized by a pre-mixed charge (i.e., fuel and air are mixed prior to ignition) and an external ignition source such as a spark plug. Pre-mixing can occur in the intake manifold or in-cylinder. While the pre-mixed charge has a relatively homogeneous spatial distribution of air and fuel in most applications, the distribution can also be heterogeneous. Combustion is initiated by a spark and the flame propagates outwards along a front from the spark location. Combustion in SI engines is said to be kinetically controlled because the entire mixture is flammable and the rate of combustion is determined by how quickly the chemical reaction can consume this mixture starting from the ignition source.
Conventional diesel engines are characterized by fuel injection directly into the cylinder approximately at the time ignition is required. As a result, the charge of air and fuel in these engines is very heterogeneous with some regions being over-rich and others being over-lean. Between these extremes, a mixture of fuel and air will exist in varying proportions. Upon injection, the fuel evaporates in this high temperature environment and mixes with the hot surrounding air in the combustion chamber. The temperature of the evaporated fuel reaches its auto-ignition temperature and ignites spontaneously to start the combustion process. The auto-ignition temperature of fuel depends on its chemistry. Unlike the SI system, combustion in compression-ignited engines can occur at many points where the air-fuel ratio and temperature can sustain this process. The bulk of the combustion process in CI engines is said to be mixing controlled because the rate is controlled by the formation of ignitable mixtures of air and fuel in the combustion chamber.
The distinction between SI and CI engines can be blurred in some cases. Due to pressures to reduce emissions and fuel consumption, combustion systems have been developed that can use some of the features of both SI and CI engines; for example, spontaneous ignition of premixed mixtures of gasoline, diesel fuel or a mixture of the two.
In external combustion engines, the working fluid is entirely separated from the fuel-air mixture. Heat from the combustion products is transferred to the working fluid through the walls of a heat exchanger. The steam engine is a well known example of an external combustion engine.
An example of a reciprocating external combustion engine is the Stirling engine where heat is added to the working fluid at high temperature and rejected at low temperature. Heat added to the working fluid can be generated from practically any heat source, such as burning fossil fuels, wood, or any other organic material.
An internal combustion engine (ICE or IC engine) 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 typically applied to pistons (piston engine), turbine blades (gas turbine), a rotor (Wankel engine), or a nozzle (jet engine). This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.
The first commercially successful internal combustion engine was created by tienne Lenoir around 1860,[1] and the first modern internal combustion engine, known as the Otto engine, was created in 1876 by Nicolaus Otto. The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar two-stroke and four-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] though of a type so specialized that they are commonly treated as a separate category, along with weaponry such as mortars and anti-aircraft cannons.) 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 for external combustion engines include air, hot water, pressurized water or even boiler-heated liquid sodium.
While there are many stationary applications, most ICEs are used in mobile applications and are the primary power supply for vehicles such as cars, aircraft and boats. ICEs are typically powered by hydrocarbon-based fuels like natural gas, gasoline, diesel fuel, or ethanol. Renewable fuels like biodiesel are used in compression ignition (CI) engines and bioethanol or ETBE (ethyl tert-butyl ether) produced from bioethanol in spark ignition (SI) engines. As early as 1900 the inventor of the diesel engine, Rudolf Diesel, was using peanut oil to run his engines.[3] Renewable fuels are commonly blended with fossil fuels. Hydrogen, which is rarely used, can be obtained from either fossil fuels or renewable energy.