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Basic principles of operation and applicationsof the Stirling engine from its invention in
1816 to its modern uses
Presented by: Dr. John Walsh
Limerick Institute of Technology
Department of Mechanical and Automobile Engineering
School of Science, Engineering and Information Technology
Engineering Technology Teachers Association
Conference 2012
Athenry, Co. Galway
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Solar power generation is one of the modern ways in which
Stirling engine technology is used.
The Stirling engine
ETTA conference 2012
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Presentation Contents:
oHistory of the Stirling engine
o Stirling engine principles of operation
o The main components of a Stirling engineo The Stirling engine cycle: Gamma and
Beta
o Stirling engine performanceoApplications of the Stirling engine
The Stirling engine
ETTA conference 2012
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Invented in 1816 by Robert Stirling
The Stirling engine was originally
known as a hot air engine
First closed cycle hot-air engine
Produces power by repeatedly heating
and cooling a fixed amount of gas
sealed inside the engine
Intended as safer alternative to the
steam engine
The Stirling engine
ETTA conference 2012
History of the Stirling Engine
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The Stirling engine
ETTA conference 2012
An improved Stirling engine wasinstalled at a Dundee iron foundry
in 1843 to drive machinery.
Engine produced thirty-seven
horse-power (27.6 kW)
Quieter, safer, and more efficient
than the steam engines of the day,
butit was not a success.
More prone to breakages than thesteam engine due to its higher
operating temperatures
History of the Stirling Engine
Replaced by a now safer steam engine
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Stirling engine was unable to compete with the steam
engine on an industrial scale
Continued in use for smaller applications, the Stirling engine
is remarkably quiet and reliable at lower power outputs.
Stirling engines, unlike steam engines, could be operated
safely by people with no background in engineering.
End of the 19th century: Number of Stirling engines inoperation declinedInternal combustion engine and the
electric motor
The Stirling engine
ETTA conference 2012
History of the Stirling Engine
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Forgotten about until in 1936: Philips needed an efficientengine to power radio receivers.
Over the next 20 years: Stirling engine usage investigated
for automotive, solar, cryocooler & submarine applications
Philips coined the name Stirling engine
The Stirling engine in modern times:
o Solar energy.
o
Computer chip coolingo Domestic CHP units
o Cryocooler technology
o Backup power supply for submarines
The Stirling engine
ETTA conference 2012
History of the Stirling Engine
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Heating a gas causes it toexpand
The Stirling engine
ETTA conference 2012
How does the Stirling engine work?
Cooling a gas causes it tocontract
Heating and cooling causes linear movement of the piston 9Dr. John Walsh
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Piston linked to a circular disc, known as a flywheel
Flywheel converts linear movement to rotational movement
Flywheels momentum needed for continuous operation.
Mechanical energy generated from temperature difference
The Stirling engine
ETTA conference 2012
How does the Stirling engine work?
Flywheel
Principle of a Heat engine power
from temperature difference 10Dr. John Walsh
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Stirling engine is an externalcombustion engine
Ability to generate power from any source of heat
The Stirling engine
ETTA conference 2012
How does the Stirling engine work?
External heat
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Three layouts for Stirling engines: 1.Alpha, 2. Beta and 3. Gamma
The Stirling engine
ETTA conference 2012
Stirling engine types
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Three components common to all Stirling engines:
The power pistonconnected to a flywheel via a
crankshaft to provide the output power of the engine
The displacermoves the air from one end of the
cylinder to the other, unique to a Stirling engine
The regeneratorreduces the amount of waste heat in
the engine cycle to improve the efficiency of the engine,unique to a Stirling engine.
The Stirling engine
ETTA conference 2012
Stirling engine main components
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Heat is applied to one end of the displacer cylinder andextracted at the opposite end
Displacer does not affect the pressure, it is not a piston,
but instead controls the position of the gas in the cylinder
The Stirling engine
ETTA conference 2012
The displacer and power pistons
When the displacer
moves, the air has
to move round the
displacer to get tothe other end of the
cylinder
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Displacer
movement
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Displacer at cold end: gas at hot end increasing intemperature and pressure
Displacer moves from cold end to hot end, pressurised gas is
forced to the cold end, pushing the power piston forward
The Stirling engine
ETTA conference 2012
The displacer and power pistons
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When the displacer is at the hot end, the air is forced to the
cold end. The air contracts and pulls the piston back
The Stirling engine
ETTA conference 2012
The displacer and power pistons
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Positioned in the air
passageway between
the hot and cold ends
of the displacer
cylinder
The regenerator is a
thermal store as gas
moves between hot
and cold ends
The Stirling engine
ETTA conference 2012
The regenerator
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Stage 1 Expansion (Heating)
Power producing phase cycle
Gas at hot end
Expands to drive power piston
Stage 2 Transfer
Gas is moved around the displacer
to the cold end
The Stirling engine
ETTA conference 2012
The gamma Stirling engine cycle
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Stage 3 Contraction (Cooling)
Gas has moved to the cold end.
Gas cools and contracts,
allowing the piston inward.
Stage 4 Transfer
Power piston is top of its stroke, ready
to start the power output.
Gas transferred to hot end
The Stirling engine
ETTA conference 2012
The gamma Stirling engine cycle
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The Stirling engine
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Stage 1 Expansion (Heating)
Power producing phase cycle
Gas at hot end
Expands to drive power piston
Stage 2 Transfer
Gas is moved around the displacer
to the cold end
The Stirling engine
ETTA conference 2012
The beta Stirling engine cycle
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Stage 3 Contraction (Cooling)
Gas has moved to the cold end.
Gas cools and contracts,
allowing the piston inward.
Stage 4 Transfer
Air is fully cooled at the cold end
of the cylinder.
Flywheel momentum transfers
gas to hot end
The Stirling engine
ETTA conference 2012
The beta Stirling engine cycle
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The Stirling engine
ETTA conference 2012
Stirling engine performance
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The Stirling engine
ETTA conference 2012
Stirling engine performance
Example:If the room temperature in which the Stirling engine is
operating is 20C.
Butane is to be used as the fuel source. If the temperature
of a butane flame is 600C.
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The greater the temperature difference between the hot end
and cold end the greater the efficiency of the Stirling engine
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Advantages of the Stirling Engine
Operate using any available heat source.
Closed cycle - gas is unpolluted.
Simple engine design. Remarkably quite
Operates at lower pressures.
No phase changes take place in the engine
Continuous combustion - lower emissions/higher efficiency
Small engine sizes possible
Greater flexibility of applications.
The Stirling engine
ETTA conference 2012
Stirling engine performance
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The Stirling engine
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Disadvantages of the Stirling Engine
Low power to weight ratio
More expensive than internal combustion engines for
same power output. Not self-starting.
Require a longer warm up time
Efficiency drops if the temperature difference between the
hot and cold ends decreases.
Difficult to vary the power output
Sealing of Stirling engines is extremely difficult.
The Stirling engine
ETTA conference 2012
Stirling engine performance
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The Stirling engine
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Solar Power GenerationStirling solar units are capable of generating 25kW electricity
The Stirling engine
ETTA conference 2012
Applications of the Stirling engine
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The Stirling engine
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Automobiles using Stirling enginesResearch led by General Motors and Fordnot a success
The Stirling engine
ETTA conference 2012
Applications of the Stirling engine
Low power to
weight ratioMore expensive
than internal
combustion engines
for same poweroutput.
Require a longer
warm up time
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Computer chip coolingMicro-Star International Co., Ltd, Taiwan. Miniature Stirling
engine. Uses heat from the processor to cool the processor
The Stirling engine
ETTA conference 2012
Applications of the Stirling engine
MSI claim the engine is 70 per cent efficient
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The Stirling engine
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Domestic heat and power - Stirling CHP unitFuel drives Stirling engine to generate mechanical power to
produce electricity. Waste heat from engine heats home.
The Stirling engine
ETTA conference 2012
Applications of the Stirling engine
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The Stirling engine
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g g
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Low temp. difference type Stirling engine
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The Stirling engine
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g g
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Thank You
All Questions Welcome
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Basic principles of operation and applications
of the Stirling engine from its invention in1816 to its modern uses
Presented by: Dr. John Walsh