The document discusses Stirling engines, including their history, types (Alpha, Beta, Gamma), efficiency comparison to internal combustion engines, key components, and advantages/disadvantages. Stirling engines operate using cyclic compression and expansion of a gas between hot and cold temperatures to convert heat into mechanical work. They were invented in the 1800s as a safer alternative to steam engines and can achieve higher efficiencies than internal combustion engines. The main types differ in their piston arrangements, and key components include the working gas, heat exchangers, displacer, regenerator, and expansion/compression mechanisms. Advantages include quiet operation and ability to use various heat sources, while disadvantages include higher costs and lack of power flexibility.

1. UMAR AZEEM
13033386-018

3. We Discuss About
 Stirling engine
 History
 Types of stirling engine
Efficiency comparison of I.C & E.C
engine
Five main components of stiriling engine
Application

4. STIRLING ENGINE
 A Stirling engine is a external
combustion heat engine that operates by
cyclic compression and expansion of air or
other gas (the working fluid) at different
temperatures, such that there is a net
conversion of heat energy to
mechanical work.
 The Stirling engine is noted for high
efficiency compared to steam engines, quiet
operation, and its ability to use almost any
heat source.

5. The Stirling Engine is one of the hot air
engines. It was invented by Robert
Stirling (1790-1878) and his brother
James. His father was interesting in
engine and he inherited it. He became
a minister of the church at Scotland in
1816. At this period, he found the
steam engines are dangerous for the
workers. He decided to improve the
design of an existing air engine. He
hope it wound be safer alternative.
HISTORY

6. • 1-2: constant
volume process
• 2-3: isothermal
expansion
process
• 3-4: constant
volume process
• 4-1: isothermal
compression
process
PV DIAGRAM

7. CYCLE EFFICIENCY
 Net work, Wnet = Wexp + Wcomp
 Net work, Qtotal = Qheat + Qheat + Qexp( Recovered mechanical
energy )

8. STIRLING ENGINE WORKING

9. STIRLING ENGINE WORKING
 Heating: Heat source provides
thermal energy to the engine
so that it raises pressure and
temperature of gas.
 Expansion: in this phase the
volume increases, but the
pressure and temperature
decrease, mechanical energy
is produced from heat energy
during this phase of cycle only.

10. STIRLING ENGINE WORKING
 Cooling: the gas is cooled and
temperature and pressure
decrease, so the gas is prepared
to be compressed during this
cycle.
 Compression: the pressure of gas
increases whereas its volume
decreases; a part of produced
mechanical energy is used for
processing of this phase, because
it needs an amount of work to be
done.

11. CYCLES

12. ALPHA TYPE

13. Alpha type Stirling engine
An Alpha Stirling contains two power pistons in separate cylinders, one hot
and one cold. The hot cylinder is situated inside the high temperature heat
exchanger and the cold cylinder is situated inside the low temperature heat
exchanger
Action of an alpha type Stirling engine
Most of the working gas is in contact
with the hot cylinder walls, it has been
heated and expansion has pushed the
hot piston to the bottom of its travel
in the cylinder. The expansion continues in
the cold cylinder, which is 90° behind the
hot piston in its cycle, extracting more
work from the hot gas.

14. The gas is now at its maximum
volume. The hot cylinder piston
begins to move most of the gas into
the cold cylinder, where it cools and
the pressure drops
Almost all the gas is now in the
cold cylinder and cooling
continues. The cold piston,
powered by flywheel momentum
(or other piston pairs on the same
shaft) compresses the remaining
part of the gas

15. The gas reaches its minimum
volume, and it will now
expand in the hot cylinder
where it will be heated once
more, driving the hot piston in
its power stroke

16. BETA TYPE

17. Beta type Stirling Engine
A beta Stirling has a single power piston arranged within the same cylinder on
the same shaft as a displacer piston. The displacer piston is a loose fit and does
not extract any power from the expanding gas but only serves to shuttle the
working gas between the hot and cold heat exchangers
Action of a beta type Stirling engine
Power piston (dark grey) has
compressed the gas, the displacer
piston (light grey) has moved so that
most of the gas is adjacent to the hot
heat exchange

18. The heated gas
increases in
pressure and
pushes the power
piston to the
farthest limit of
the power stroke
The displacer
piston now
moves,
shunting the
gas to the cold
end of the
cylinder.
The cooled gas is
now compressed
by the flywheel
momentum. This
takes less energy,
since its pressure
drops when it is
cooled

19. GAMMA TYPE

20. GAMMA TYPE

21. Efficiency comparison of
I.C & E.C engine
 Internal combustion engine:
Most internal combustion engines are incredibly
inefficient at turning fuel burned into usable
energy. The efficiency by which they do so is
measured in terms of "thermal efficiency", and
most gasoline combustion engines average
around 20 percent thermal efficiency.

22. Internal Combustion Engines
– Theorem Carnot cycle
Carnot's theorem is a
formal Statement of this
fact: No engine
operating between two
heat reservoirs can be
more efficient than a
Carnot engine operating
between those same
reservoirs.

23. Internal Combustion Engines
– Carnot cycle
TH is the absolute
of cold reservoir
TC is the absolute
of hot reservoir

24. Efficiency comparison of
I.C & E.C engine
 External combustion engine (Stiriling
Engine):
Inside the cylinder, the gas that expands and
contracts is usually hydrogen. Stirling engines are
one of the best options on the market to harvest
solar power as they can reach a 31% efficiency
compared to just 16% for parabolic trough
technology or 14-18% achieved by photovoltaic
panels.

25. External combustion engine
(Stiriling Engine):
During each cycle:
w is the net work done by
the engine QH is the
energy taken from the
(hot) source QC is the
energy given to the (cold)
sink

26. External combustion engine (Stiriling Engine):

27. Efficiency Stirling Engine

28. FIVE MAIN COMPONENTS OF STIRLING ENGI
 Working Gas:
The Stirling cycle is a closed cycle and the various
thermodynamic processes are carried out on a working gas that is
trapped within the system.
 Heat-Exchanger:
Two heat exchangers are used to transfer heat across
the system boundary. A heat absorbing heat-exchanger transfers
the heat from outside the system into the working gas, and a heat
rejecting heat-exchanger transfers heat from the working gas to
outside the system.
 Displacer Mechanism:
This moves(or displaces)the working gas between the
hot and cold ends of the machine (via generator).

29.  Regenerator:
This acts both as a thermal barrier between the hot and
cold ends of the machine, and also as a “thermal store”for the
cycle. Physically a regenerator usually consists of a mesh materiaL
and heat is transferred as the working gas is forced through the
regenerator mesh
 Expansion/Compression Meahanism:
This expands and compresses the working gas.In an
engine this mechanism produces a net work output.

30. ADVANTAGES OF STIRLING ENGINE
 Silence of operation :
There is no expansion in the atmosphere like in the case of an internal
combustion engine, combustion is continuous outside of the cylinders. In
addition, its design is such as the engine is easy to balance and generates
few vibrations.
 The high efficiency :
It is function of the temperatures of the hot and cold sources. As it is
possible to make it work in cogeneration (mechanical and caloric powers),
the overall efficiency can be very high.
 The multitude of possible “hot sources” :
Combustion of various gases, wood, sawdust, waste, solar or geothermic
energy...
 Reliability and easy maintenance:
The technological simplicity makes it possible to have engines with a very
great reliability and requiring little maintenance.

31. DISADVANTAGES OF STIRLING
ENGINE
 The price : its cost is probably the most important problem, it is not yet
competitive with other means well established. A generalization of its
employment should solve this problem inherent in any novelty.
 The lack of flexibility : the fast and effective variations of power are
difficult to obtain with a Stirling engine. This one is more qualified to run
with a constant nominal output. This point is a great handicap for an
utilization in car industry.
 Stiriling engine requires a blower to force air through preheater and
combustion chamber ,this reduces engine efficiency and noise