1. Prepared by
Gaurav Bhati
SOT, PDPU

2. ENERGY CONVERSION
 The distinctive Feature of our civilization today , one that
makes it different from all others, is the wide use of
mechanical power.
 At one time the primary source of power was chiefly man’s
muscles.
 The great step was taken in this direction when man
learned the art of Energy convrsion from one form to
another.
 The machine which does the job of energy conversion is
called an ENGINE.

3. Definition of Engine
 A device that transforms one form of energy into other
form of energy.
HEAT ENGINE:
A device that transforms chemical energy of fuel into
thermal energy which is utilized to perform useful
mechanical work.
Heat engine can be broadly classified into two
categories:
(i) Internal Combustion Engines
(ii) External Combustion Engines

5. History
 The first working internal combustion engine for
automobiles was Francois Isaac of Switzerland in 1807.
Mixing hydrogen and oxygen for fuel.
 The first gasoline powered engine was built in 1864 by
Siegfried Marcus and was said to be the forerunner to the
modern automobile.
 In 1876 two of the greatest engines were invented, i-e two
stroke engine by Nikolaus Otto and four stroke engine by
Dougald Clerk. This started the rise of better and more
efficient engines.

7. CLASSIFICATION OF HEAT ENGINES
HEAT ENGINES
IC ENGINES EC ENGINES
ROTARY RECIPROCATING
ROTARY RECIPROCATING
Open Cycle
Gas Turbine
Wankel
Engine
Gasoline
Engine
Diesel
Engine
Steam
Turbine
Gas
Turbine
Steam
Engine
Stirling
Engine

8. Advantage of Reciprocating IC
engine
 The most widely used are the reciprocating internal
combustion engine, The Gas turbine and Steam
turbine.
 The reciprocating internal combustion engine have
absence of heat exchangers in the passage of the
working fluid.
 This result in a considerable mechanical simplicity and
improved power plant efficiency of the IC engine.
 All its component work at an average temperature
which is much below the maximum temperature of
the working fluid in the cycle.

9. Disadvantage
 The main disadvantage of this type of engine is the
problem of vibration caused by the reciprocating
components.
 Also, it is not possible to use a variety of fuels in these
engines.
 These fuels are relatively more expensive.

11. CLASSIFICATION OF IC ENGINES
IC Engines
4-Stroke 2-Stroke
SI CI
Petrol Gas
Dual
Fuel
Divided
Chamber
Carburetor Type Injection Type
Battery Ignition Magneto Ignition
Swirl
Chamber
Pre
Chamber
Water Cool Air Cool
Reciprocating Muti-cylinder Reciprocating Single Cylinder Rotary (Wankel)
V-Cylinder
(4/6/8/12)
Inclined –Cylinder
( 2/4/6)
Opposed Cylinder
(2/4/6)

12. Reciprocating IC engines
 Reciprocating internal combustion engines uses
one or more reciprocating pistons to convert pressure
into a rotating motion.
Types of reciprocating IC engines:
 Spark ignition (SI)
 Compression ignition (CI)

13. Engine Components
•Cylinder Block
Main supporting structure
•Cylinder
Where piston makes a
reciprocating motion
•Piston
Cylindrical component fitted
into the cylinder which forms
the first link in transmitting the
gas forces to the output shaft.
•Combustion Chamber
Space enclosed in the upper
part of the cylinder, by the
cylinder head and piston top
•Inlet Manifold
Pipe which connects the intake
system to the inlet valve

14. Engine Components
•Inlet and Exhaust Valves
Provided on the cylinder head
or on the side of the cylinder
•Spark Plug
Located on cylinder head
•Connecting Rod
Interconnects the piston and
the crankshaft
•Crankshaft
Converts the reciprocating
motion into useful rotary
motion of the output shaft
•Piston Rings
Fitted into the slots around the
piston, provide a tight seal
between piston and the
cylinderwall

15. Engine Components
•Gudgeon Pin
Forms the link between the
small end of CR and the piston
•Cams
Integral part designed to open
the valves at correct timing
•Fly Wheel
To achieve a uniform torque

16. Nomenclature
Cylinder Bore (d)
•The nominal inner diameter of the
working cylinder (mm).
Piston Area (A)
• The area equal to cylinder bore
(cm2) .
Stroke (L)
• Nominal distance through which a
working piston moves L and is
expressed usually in millimeter
(mm).
Stroke to Bore Ratio(L / d)
• If d < L, under-square engine
• If d = L, square engine
• If d > L, over-square engine
•An over stroke can operate at higher
speeds because of larger bore and
shorter stroke

17. Nomenclature
Dead Centre
•The position of the at either end of
the stroke.
•Top Dead Centre (TDC) :
When the piston is farthest from the
crankshaft
•Bottom Dead Centre (BDC): when
the piston is nearest to the
crankshaft
Swept Volume (Vs)
•Nominal volume swept by the
working piston when travelling from
one dead centre to the other. It is
expressed in terms of cubic
centimeter (cc)
and given by

18. Nomenclature
 Cubic Capacity or Engine Capacity
Displacement volume of a cylinder multiplied by
number of cylinders . If there are K cylinders in an
engine, then
Cubic capacity = Vs x K
 Clearance Volume (Vc)
The nominal volume of the combustion chamber above
the piston when it is at the top dead centre is the
clearance volume.

19. Nomenclature
 Compression Ratio (r)
It is the ratio of the total cylinder volume when the
piston is at the bottom dead centre, Vr, to the
clearance volume, Vc.
r = VT/Vc = Vc+Vs / Vc