4 stroke diesel engine

it is a perfect report if you are searching for 4 Stroke Diesel Engine. It includes History, Construction, Components, Working Principle, Strokes, PV Diagram, Advantages & Disadvantages and Applications.

1. THERMODYNAMICS LAB REPORT
4 STROKE PETROL ENGINE

Submitted to:
Dr. M.M. Bhutta
Submitted by:
Haris Riaz
2020-ME-61

2.  INTRODUCTION:
 Engine:
An engine is motor which converts chemical energy into
mechanical energy.
 Fuel/diesel engine:
A diesel engine is an internal combustion engine with
compression-ignition, designed to run on diesel and similar
volatile fuels.
 Four Stroke Engine:
A four-stroke engine (also known as four-cycle) is an internal
combustion engine in which the piston completes four
separate strokes which comprise a single thermodynamic
cycle. A stroke refers to the full travel of the piston along the
cylinder, in either direction.
 FOUR STROKE DIESEL ENGINE:
 A diesel engine is an internal combustion engine.
 It uses the heat of compression to initiate ignition to burn the fuel that has
been injected into the combustion chamber.
 The engine was developed by German inventor Rudolf Diesel in 1893.
 The engine works on the principle of diesel cycle.
 CHARACTERISTICS:
 No Throttle Valve.
 Heat of compression ignites fuel as its sprays into engine cylinder.
 It has a high compression ratio of 16:1 to 22:1.

3.  It can control engine power and speed only by the amount of fuel sprayed
into the cylinders.
 COMPONENTS:
 Cylinder Block
 Cylinder Liners
 Cylinder Head
 Head Gaskets
 Crankshaft
 Cams & Camshaft
 Timing Gears
 Crank Case
 Piston
 Connecting Rods
 Flywheel
 Main Bearings
 Valve
 Cylinder Block:
Cylinder block, the
basic foundation of an engine, includes
passages for cooling water and opening for
valves. Make with gray cast iron, semi-steel,
aluminum or aluminum alloy.
 Cylinder Liners:
A cylinder liner is a cylindrical part
to be fitted into an engine block to form a cylinder. It is
one of the most important functional parts to make up the
interior of an engine.
 Head Gaskets:
Figure 1:
Cylinder Block
Figure 2: Cylinder
Liners

4. The head gasket is compressed
between the engine block and the cylinder head.
The head gasket seals in the internal combustion
process and also keeps coolant and oil from mixing
together as the two fluids travel from the engine block
to the cylinder head.
 Cylinder Head:
In an internal combustion engine, 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.

 Crankshaft:
The power from an engine is
taken at the crankshaft. It is one-piece casting or
forging of heat-treated alloy steel. One revolution of
crank shaft is one half of piston stroke (four stroke
engine) It has drilled oil passages through which oil can
flow from main to big end bearing.
 Cam & Camshaft:
A camshaft is a
rotating object— usually made of metal— that
contains pointed cams, which converts rotational
motion to reciprocal motion. Camshafts are used in
internal combustion engines, mechanically
controlled ignition systems and early electric motor
speed controllers.

 Timing Gears:
Figure 3: Head Gaskets
Figure 4: Cylinder
Head
Figure 5: Crankshaft
Figure 6: Camshaft

5. Timing Gear is a
component of an internal combustion engine
which is connected by a chain, gears, or a belt
to the crankshaft on one end and the camshaft
on the other. It is marked with tiny increments
all around its perimeter which correspond to
degrees of timing from the straight-up timing
position of the camshaft and crankshaft. These marks
assist the individual who is tuning up the engine to set the timing to the
determined optimal timing degrees of the camshaft and engine designers.
 Crank Case:
A crankcase is the housing for the
crankshaft in a reciprocating internal combustion
engine. In most modern engines, the crankcase is
integrated into the engine block.
 Piston:
A piston is a moving disk enclosed in a
cylinder which is made gas-tight by piston rings. Pistons
work by transferring the force output of an expanding gas
in the cylinder to a crankshaft, which provides rotational
momentum to a flywheel.
Figure 7: Timing Gear
Figure 8:
Crankcase
Figure 9: Piston

6.  Connecting Rod:
A connecting rod, also called a con rod, is
the part of a piston engine
which connects the piston to the crankshaft.
Together with the crank, the connecting
rod converts the reciprocating motion of
the piston into the rotation of the crankshaft.
 Fly Wheel:
A flywheel is a mechanical device specifically
designed to use the conservation of angular momentum so
as to efficiently store rotational energy; a form of kinetic
energy proportional to the product of its moment of inertia
and the square of its rotational speed.
 Inlet Valve:
Its function is to intake the fresh air-fuel mixture into the
cylinder.
 Exhaust Valve:
Its function is to exhaust is the burnt
gases by the force of piston.
 DIESEL CYCLE
 The diesel engines work on the principle of Diesel cycle, also called
constant pressure heat addition cycle.
 The four stroke diesel engine cycle also consists of intake, compression,
power and exhaust strokes.
 The basic construction of a four stroke diesel engine is same as that of four
stroke petrol engine, expect instead of spark plug, a fuel injector is
mounted in its place.


Figure 10: Connecting
Rod
Figure 11: Fly Wheel
Figure 12: Intake &
Exhaust Valve

7.  A fuel pump supplies the fuel oil to the injector at higher pressure.
1. Intake Stroke:
 During this stroke, inlet valve opens and
exhaust valve is closed, the pressure in the
cylinder will be atmospheric.
 As the piston moves from TDC to BDC, the
volume in the cylinder increases, while
simultaneously the pressure decreases.
 This creates a pressure difference between the
atmosphere and inside of the cylinder.
 Due to this pressure difference only the
atmospheric air will enter into the cylinder
through air filter and inlet.
 At the end of this stroke, the cylinder will be
filled completely with air and inlet valve will be closed.
Figure 13: PV Diagram Diesel
Cycle
Figure 14: Intake Stroke

8. 2. Compression Stroke:
 During this stroke, both inlet valve and exhaust valve
remain closed.
 The piston moves from BDC to TDC. As this stroke is
being performed, the air in the cylinder will be
compressed, so pressure and temperature of air
increases.
 The compression ratio of this engine is higher than
petrol engine.
 Due to higher compression ratio, air will have attained
a higher temperature than self-ignition temperature
of the diesel fuel.
 Near the end this stroke, a metered quantity of the
diesel fuel is injected into the cylinder.
 As the diesel fuel particles come in contact with high
temperature air, it will ignite automatically.
 This is called auto-ignition or self-ignition.
 In this engine compressed air ignites the diesel fuel, this
type of engine is also called as compression ignition
Engine or C.I. engine.
3. Power Stroke:
 During this stroke, both the inlet valve and the exhaust
valve are closed.
 The piston moves from TDC to BDC.
 The fuel injection starts nearly at the end of compression
stroke, but the rate of fuel injection is such that
combustion maintains constant pressure.
 The piston is forced further during the remaining part of
this stroke only due to the expansion of the burnt gases.
 The engine produce mechanical work or power during
this stroke.
Figure 15: Compression
Stroke
Figure 16: Power Stroke

9.  As the piston moves from TDC to BDC, the pressure of hot
gases gradually decreases and volume increases
4. Exhaust Stroke:
 During this stroke, the exhaust valve opens and inlet
valve is closed.
 The piston moves from BDC to TDC.
 During this motion, piston pushes the exhaust gases
(combustion product) out of cylinder at constant
pressure.



 ADVANTAGES & DISADVANTAGES:
 Advantages:
 More efficient.
 More reliable.
 More durable.
 Release less amount of harmful fumes.
 Easily turbo-charged.
 Produce minimal carbon monoxide.
 Can easily accept synthetic fuels.
 Lower fuel cost as compared to Gasoline Engine
 Disadvantages:
 More expensive.
 Occasionally servicing can be more costly.
 Parts tend to be more expensive.
 The cost of diesel at the pump is higher.
 Contribute to Greenhouse effect.
 Generally more noisy.
Figure 17: Exhaust Stroke

10.  APPLICATIONS:
Diesel engines are commonly used as mechanical engines, power
generators and in mobile drives. They find wide spread use in locomotives,
construction equipment, automobiles, and countless
industrial applications.