THERMODYNAMICS

LAB REPORT 12: ENGINE AND ITS PARTS

Submitted by: Hamna Anwaar Registration no: 335763

Objectives:
1. To learn about engine and its parts.

2. To learn about the types of engines.

Introduction:
This report contains details about what an engine is, how it works, what are its types and how it
evolved to become the way we know it today. It is basically a device which can convert heat
energy of fuel into mechanical energy is known as engine or heat engine. Engine is widely used
in automobile industries.

Principle:
Mainly, the engine has only one principle; that is to convert heat or electric energy into
mechanical energy. Basically, reactions convert the chemical energy of fuel into mechanical
energy and heat energy that escapes into the environment.

This is accomplished by various types of engines discussed below.

Theory:
An engine can also be called a motor or a machine. It has moving parts and can convert power
into motion. An engine converts electrical or heat energy into mechanical energy. There are
pistons that move up and down inside metal tubes called cylinders. Pistons are connected via
rods to a crankshaft, and they move up and down to spin the engine's crankshaft. In case of a fuel
based engine; each time the fuel ignites is called the combustion, or power, stroke. The heat and
expanding gases from this miniexplosion push the piston down in the cylinder.

Engines are used in cars, electric water motors, etc.

In 1807, an IC engine was invented. This engine used a mixture of hydrogen and oxygen for fuel.
Afterwards, this engine was fueled by coal gas and then soon with steam. In 1876, the first four-
cycle engine was introduced. This engine had four cylinders. Soon the invention of the spark
plug, the ignition magneto, the coil ignition, and the spray jet carburetor took place. Between
1892 and 1893, Dr. Rudolf Diesel developed the first heat engine type motor. His name is where
we got the word diesel. Soon engines began to be used in cars and motorcycles. This engine was
the intake over exhaust engine.

Environmental significance :
In the beginning of times people used to generate power from the heat energy created by burning
of wood. Or they created mechanical power using manual labor or horse/cattle power. These
rotated turbines, watered their fields and so on.

These practices, however were time consuming. With time we have now evolved the engines that
we use. But at the same time we have also increased their environmental impacts.

Among internal combustion engines, diesel fuel combustion engines produce less emissions than
gasoline. Biofuel combustion engines are also considered, but they make up almost negligible of
the automotive population.

Automobiles have contributed to the destruction of our environment in the form of carbon
dioxide since their creation. Emitting carbon dioxide into the environment increases the global-
mean surface warming, and about 20 percent of all CO2 emissions originate from road traffic

Diesel emissions include a number of biologically active substances. Diesel particulates and the
associated organic phase became a major health concern. From the environmental perspective,
the advantages of diesels are low “greenhouse gas” and hydrocarbons emissions; their drawback
is high NOx emission.

Combustion engines produce a number of air pollutant emissions, as there are carbon monoxide
(CO), sulfur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), volatile organic compounds
(VOC), aromatic hydrocarbons (PAH) and particulate matter (PM) of different sizes.
Chemical processes can produce secondary pollutants under specific atmospheric conditions as
for instance ozone (O3) and secondary particulate matter (nitrates or sulfates). 

Working of different types of engines:

Based on place of fuel combustion:

EC engine IC Engine
An external combustion engine combusts An IC engine combusts fuel inside the
fuel outside the cylinder. cylinders. When the fuel burns inside
It is mostly used to boil water to make cylinder high T and P are generated.
steam. This is used to rotate a turbine. This high pressure exerts force on piston
 Any solid, liquid and gases fuel can be used which used to rotate the wheels of
These are used in driving locomotive, ships, vehicle. In these engines, only gases and
generation of electric power etc high volatile fuel like petrol and diesel can
be used. These are used in automobile
industries, generation of electric power
etc

Based on number of strokes:

Two stroke engine Four stroke engine

There is only one piston that moves once up The piston moves twice up and down in
and then down in the cylinder to complete the cylinder and completes two
one crankshaft revolution. This is done in a crankshaft revolutions in a single time of
single time of fuel injection fuel burn. This type of engines has high
This type of engine has high moment if average if compared to two stroke
compared to the four stroke engine. These engine. These are generally used in bikes,
are generally used in scooters, pumping sets cars, truck etc.

etc

Based on fuel used:

 Diesel engine Petrol engine Gas engine Electric engine
Fuel used is Fuel used is Fuel used is CNG This engine is eco-
diesel. They petrol. These are and LPG. These friendly. It doesn’t
are used in used in bikes, are used in some require fuel for burning.
trucks, cars luxury cars, sport light motor They require electric
buses etc. cars, etc. vehicles. energy to rotate wheel.

Based on method of ignition:

Compression ignition engine Spark ignition engine

There are no parts that cause ignition so The spark plug causes ignition inside the
burning of fuel starts on account of cylinder.
temperature rise while air is being Hence the name; spark ignition engine.
compressed.
Hence the name; compression ignition
engine.

Based on cylinders:
 Single cylinder engine Multi-cylinder engine
There are only one cylinder and one There are more than one cylinder and piston
piston connected to the crank shaft. connected to the crank shaft

Parts:
Name Description
Spark plug Provides spark that ignites the air/fuel in order to make combustion
happen. It should act at a precise time for the engine to properly work.
Valve The intake and exhaust valves open at the proper time to let in air and
fuel and to let out exhaust. Both valves are closed during compression
and combustion in order to seal the combustion chamber.

Piston A piston is a cylindrical piece of metal that moves up and down inside the
cylinder

Piston Rings Provide with a slide sealing between the outside of the piston and the
inside of the cylinder. They don’t allow the fuel/air mixture and exhaust in
the combustion chamber to leak into the sump during compression and
combustion. Also, they make sure oil in the sump does not leak and go in
combustion area, where it would be burned and lost.

Connecting The connecting rod connects the piston to the crankshaft

rod It can rotate at both ends so that its angle can change as the piston moves
and the crankshaft rotates
Crankshaft The crankshaft turns the piston's up-and-down motion into circular
motion just like a crank on a jack-in-the-box does

Sump The sump surrounds the crankshaft

It contains some amount of oil, which collects in the bottom of the sump
(the oil pan)

Engine block Engine block is an important parts of an engine

It is made by pouring the molten iron or aluminum alloy into a mold

The mold is made such that we should have required number of holes in
the casted block, which are said to be the number of cylinders of an
engine or engine cylinders

The diameter of these holes is called the bore of an engine.

Engine head Engine head is casted in the same way as engine block

Its mold is made such that the casted piece must have an opening for air
to flow into engine cylinder and an exhaust opening from where the burnt
gases will go out

Camshaft It is a shaft with a number of cam profiles along its length

So it regulates the valves opening and closing time

It does so by pressing the end of valve stem by its cam profile

Timing belt Timing belt transmits the motion of gear mounted at crankshaft called
crank-gear, to the gear mounted at camshaft

The ration of cam-gear to that of crank-gear is 2:1

So that camshaft would rotate only once in two rotations of crankshaft

Gasket It is generally a paper like sheet which is placed between engine block and
engine head

Gasket gives insulation from water or oil leaking into engine cylinder or
air-fuel mixture from engine cylinder leaking out from joint of engine
 block and engine head

Conclusions:
In this lab we saw how engines work. We learned about the parts of an engine. An engine can be on
different types based on the type of fuel they use, where the fuel is inserted, number of cylinders it has
etc. The concepts were further cleared with help of detailed labelled diagrams of engines.