ENGINE

An engine or motor is a machine designed to convert energy into useful mechanical motion or electrical energy into

pressure energy.

A common type of engine is a heat engine such as an internal combustion engine which typically burns a

fuel with air and uses the hot gases for generating power. External combustion engines such as steam engines use

heat to generate motion via a separate working fluid.

The internal combustion engine (IC engine) is an engine in which the combustion of

a fuel (generally, fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber. In an internal

combustion engine the expansion of the high temperature and high pressure gases, which are produced by the

combustion, directly applies force to components of the engine, such as the pistons or turbine blades or a nozzle, and

by moving it over a distance, generates useful mechanical energy

An external combustion engine (EC engine) is a heat engine where an internal working fluid is heated by

combustion of an external source, through the engine wall or a heat exchanger. The fluid then, by expanding and

acting on the mechanism of the engine produces motion and usable work. The fluid is then cooled, compressed and

reused (closed cycle), or (less commonly) dumped, and cool fluid pulled in (open cycle air engine).

The IC engines are classified as:

1. SI engines

2. CI engines

The SI (Spark Ignition) engines are operated by a spark plug. It has a low compression ratio of 8:1 to 10:1.

This engine is where the initiation of the combustion process of the air-fuel mixture is ignited within the combustion

chamber by a spark from a spark plug.

The CI (Compression Ignition) engines are operated by a fuel injector. It has a high compression ratio of

14:1to 22:1. This engine uses the heat of compression to initiate ignition to burn the fuel, which is injected into the

combustion chamber during the final stage of compression

GENERATOR

Electric generator is a device that converts mechanical energy (from the engine) to electrical energy. A

generator forces electrons in the windings to flow through the external electrical circuit. It is somewhat analogous to

a water pump, which creates a flow of water but does not create the water inside.

ALTERNATOR

An alternator is an electromechanical device that converts mechanical energy to electrical energy in the

form of alternating current. Most alternators use a rotating magnetic field but linear alternators are occasionally

used. In principle, any AC electrical generator can be called an alternator, but usually the word refers to small

rotating machines driven by automotive and other internal combustion engines. Alternators in power stations driven

by steam turbines are called turbo-alternators.

CYLINDER AND CYLINDER HEAD

A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston

travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast

from aluminum or cast iron before receiving precision machine work. The cylinder head sits above the cylinders on

top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed

by a head gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder,

and that allow the exhaust to escape. The head can also be a place to mount the valves, spark plugs, and fuel

injectors.

FUEL SYSTEM

In any internal combustion engine, fuel and oxygen are combined in a combustion process to produce the

power to turn the crankshaft of the engine. The job of the fuel system is to mix the fuel and air (oxygen) in just the

right proportions for combustion and to distribute the fuel/air mixture to the combustion chambers

PISTON AND PISTON RINGS

The piston is the moving component that is contained by a cylinder and is made gas-tight by piston rings.

In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston

rod and/or connecting rod. Piston rings provide a sliding seal between the outer edge of the piston and the inner

edge of the cylinder. The rings serve two purposes:

They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump

during compression and combustion.

They keep oil in the sump from leaking into the combustion area, where it would be burned and lost.

CRANKSHAFT

The crankshaft is a single, long piece of metal which is cut into a very specific "snake" shape. The ends of

the shaft are rounded to accept the flywheel and the sprockets at the right of the figure, and the timing sprocket on

the left end. The three rounded sections in the middle of the crankshaft ride on bearings in the crankcase of the

engine. There are four additional rounded sections of the crankshaft which are enclosed by the ends of the piston

rods. The piston rods are connected to the pistons by pins.

TURBOCHARGER AND TURBINE

A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work. The

simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving

fluid acts on the blades, or the blades react to the flow, so that they move and impart rotational energy to the motor.

A turbocharger, or turbo (colloquialism), is a centrifugal compressor powered by a turbine which is driven

by an engine's exhaust gases. Its benefit lies with the compressor increasing the pressure of air entering the engine

(forced induction) thus resulting in greater performance (for either, or both, power & efficiency). The compressor

draws in ambient air and compresses it before it enters into the intake manifold at increased pressure. This results in

a greater mass of air entering the cylinders on each intake stroke. The power needed to spin the centrifugal

compressor is derived from the high pressure and temperature of the engine's exhaust gases. The turbine converts the

engine exhaust's potential pressure energy and kinetic velocity energy into rotational power, which is in turn used to

drive the compressor. They are popularly used with internal combustion engines (e.g. four-stroke engines like Otto

cycles and Diesel cycles). Turbochargers have also been found useful compounding external combustion

engines such as automotive fuel cells

A turbocharger may also be used to increase fuel efficiency without any attempt to increase power. It does

this by recovering waste energy in the exhaust and feeding it back into the engine intake. By using this otherwise

wasted energy to increase the mass of air it becomes easier to ensure that all fuel is burnt before being vented at the

start of the exhaust stage. The increased temperature from the higher pressure gives a higher Carnot efficiency.

SPARK PLUG

The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark

must happen at just the right moment for things to work properly. It is an electrical device that fits into the cylinder

head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol,

and liquefied petroleum gas by means of an electric spark.

Spark plugs have an insulated central electrode which is connected by a heavily insulated wire to

an ignition coil or magneto circuit on the outside, forming, with a grounded terminal on the base of the plug, a spark

gap inside the cylinder.

A power stroke is, in general, the stroke of a cyclic motor which generates force. It is used in describing

mechanical engines. This force is the result of the spark plug igniting the compressed fuel-air mixture.

VALVES

The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that

both valves are closed during compression and combustion so that the combustion chamber is sealed

CONNECTING RODS

The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can

change as the piston moves and the crankshaft rotates. Together with the crank, they form a simple mechanism that

converts linear motion into rotating motion.

As a connecting rod is rigid, it may transmit either a push or a pull and so the rod may rotate the crank

through both halves of a revolution, i.e. piston pushing and piston pulling.

KNOCKING

Knocking (also called knock, detonation, spark knock, pinging or pinking) is an abnormal combustion

in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts

off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside

the envelope of the normal combustion front.

The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke

cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The

shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects

of engine knocking range from inconsequential to completely destructive. Knocking is produced when some un-burn

fuel is left in the chamber. The knocking is SI engine is calculated by octane rating, while in CI engines it is

calculated by cetane rating.

COGENERATION

Cogeneration (also combined heat and power, CHP) is the use of a heat engine or a power station to

simultaneously generate both electricity and useful heat. CHP systems consist of a number of individual components

– prime mover (heat engine), generator, heat recovery, and electrical interconnection – configured into an integrated

whole. The type of equipment that drives the overall system (i.e. the prime mover) typically identifies the CHP

system. Prime movers for CHP systems include reciprocating engines, combustion or gas turbines, steam turbines,

micro-turbines, and fuel cells. These prime movers are capable of burning a variety of fuels, including natural gas,

coal, oil, and alternative fuels to produce shaft power or mechanical energy. Although mechanical energy from the

prime mover is most often used to drive a generator to produce electricity, it can also be used to drive rotating

equipment such as compressors, pumps, and fans. Thermal energy from the system can be used in direct process

applications or indirectly to produce steam, hot water, hot air for drying, or chilled water for process cooling.

IGNITION (Combustion)

Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant

accompanied by the production of heat and conversion of chemical species. The release of heat can result in the

production of light in the form of either glowing or a flame. Fuels of interest often include organic compounds

(especially hydrocarbons) in the gas, liquid or solid phase.

In a complete combustion reaction, a compound reacts with an oxidizing element, such

as oxygen or fluorine, and the products are compounds of each element in the fuel with the oxidizing element. For

example:

CH4 + 2 O2 → CO2 + 2 H2O + energy

CH2S + 6 F2 → CF4 + 2 HF + SF6

A simple example can be seen in the combustion of hydrogen and oxygen, which is a commonly used

reaction in rocket engines:

2 H2 + O2 → 2 H2O (g) + heat

The result is water vapor.

Complete combustion is almost impossible to achieve. In reality, as actual combustion reactions come

to equilibrium, a wide variety of major and minor species will be present such as carbon monoxide and

pure carbon (soot or ash). Additionally, any combustion in atmospheric air, which is 78% nitrogen, will also create

several forms of nitrogen oxides.

Liquid Fuels

Combustion of a liquid fuel in an oxidizing atmosphere actually happens in the gas phase. It is the vapor that

burns, not the liquid. Therefore, a liquid will normally catch fire only above a certain temperature: its flash point.

The flash point of a liquid fuel is the lowest temperature at which it can form an ignitable mix with air. It is also the

minimum temperature at which there is enough evaporated fuel in the air to start combustion.

Solid fuels

The act of combustion consists of three relatively distinct but overlapping phases:

Preheating phase, when the unburned fuel is heated up to its flash point and then fire point. Flammable gases

start being evolved in a process similar to dry distillation.

Distillation phase or gaseous phase, when the mix of evolved flammable gases with oxygen is ignited. Energy

is produced in the form of heat and light. Flames are often visible. Heat transfer from the combustion to the

solid maintains the evolution of flammable vapors.

Charcoal phase or solid phase, when the output of flammable gases from the material is too low for persistent

presence of flame and the charred fuel does not burn rapidly anymore but just glows and later only moulds.

AUTOMATION:

Automation is the use of control systems and information technologies to reduce the need for human work

in the production of goods and services. In the scope of industrialization, automation is a step

beyond mechanization. Whereas mechanization provided human operators with machinery to assist them with

the muscular requirements of work, automation greatly decreases the need for human sensory and mental

requirements as well. Automation plays an increasingly important role in the world economy and in daily

experience.

TYPES OF ENGINES

There are many types of engine cycles like two-stroke, four-stroke, diesel cycle, five-stroke, and six-stroke.

Engines based on the four-stroke ("Otto cycle") have one power stroke for every four strokes (up-down-up-down)

and employ spark plug ignition. Combustion occurs rapidly, and during combustion the volume varies little

("constant volume"). They are used in cars, larger boats, some motorcycles, and many light aircraft. They are

generally quieter, more efficient, and larger than their two-stroke counterparts.

The steps involved here are:

1. Intake stroke: Air and vaporized fuel are drawn in.

2. Compression stroke: Fuel vapor and air are compressed and ignited.

3. Combustion stroke: Fuel combusts and piston is pushed downwards.

4. Exhaust stroke: Exhaust is driven out. During the 1st, 2nd, and 4th stroke the piston is relying on power and

the momentum generated by the other pistons. In that case, a four-cylinder engine would be less powerful

than a six or eight cylinder engine.

The cycle begins when the intake valve opens and a mixture of fuel and air is drawn into the cylinder from

the intake manifold. The piston is pulled towards the crankshaft to the left at constant pressure because the valve is

open. The motion of the piston is called a stroke. Stage 1 is the beginning of the intake stroke.

At the end of the intake stroke, the intake valve is closed and the piston is moved back towards the

combustion chamber. Since the valves are closed, the pressure and temperature are increased by the adiabatic

compression. Stage 2 is the beginning of the compression stroke.

At the end of the compression stroke, the pressure in the combustion chamber is a maximum. The spark plug

in a modern engine, or the contact switch of the Wright engine, then generates an electric spark which ignites the

fuel-air mixture. Stage 3 is the beginning of the combustion process.

Combustion occurs very quickly in an IC engine and occurs at constant volume in the combustion chamber.

The high pressure forces the piston back towards the crankshaft. Stage 4 is the beginning of the power stroke.

At the end of the power stroke, heat is rejected to the surroundings as required by the second law of

thermodynamics. Stage 5 is the beginning of the heat rejection.

Following heat rejection, the exhaust valve is opened and the residual gas is forced out into the surroundings

to prepare for the next intake stroke. Stage 6 is the beginning of the exhaust stroke.