Stirling engine presentation.pdf

8/10/2019 Stirling engine presentation.pdf

1/33

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

1


2/33

Solar power generation is one of the modern ways in which

Stirling engine technology is used.

The Stirling engine

ETTA conference 2012

Dr. John Walsh 2


3/33

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


3Dr. John Walsh


4/33

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


History of the Stirling Engine

4Dr. John Walsh


5/33


6/33

The Stirling engine


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


Replaced by a now safer steam engine

6Dr. John Walsh


7/33

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



7Dr. John Walsh


8/33

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



8Dr. John Walsh


9/33

Heating a gas causes it toexpand

The Stirling engine


How does the Stirling engine work?

Cooling a gas causes it tocontract

Heating and cooling causes linear movement of the piston 9Dr. John Walsh


10/33

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



Flywheel

Principle of a Heat engine power

from temperature difference 10Dr. John Walsh


11/33

Stirling engine is an externalcombustion engine

Ability to generate power from any source of heat

The Stirling engine



External heat

source 11Dr. John Walsh


12/33

Three layouts for Stirling engines: 1.Alpha, 2. Beta and 3. Gamma

The Stirling engine


Stirling engine types

12Dr. John Walsh

32

1


13/33

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


Stirling engine main components

13Dr. John Walsh


14/33

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


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

14Dr. John Walsh

Displacer

movement

Th Sti li i


15/33

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



15Dr. John Walsh

Th Sti li i


16/33

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



16Dr. John Walsh

Th Sti li i


17/33

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


The regenerator

17Dr. John Walsh

Th Sti li i


18/33

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


The gamma Stirling engine cycle

18Dr. John Walsh

The Stirling engine


19/33

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


The gamma Stirling engine cycle

19Dr. John Walsh

The Stirling engine


20/33

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


The beta Stirling engine cycle

20Dr. John Walsh

The Stirling engine


21/33

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


The beta Stirling engine cycle

21Dr. John Walsh

The Stirling engine


22/33

The Stirling engine


Stirling engine performance

22Dr. John Walsh

The Stirling engine


23/33

The Stirling engine



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.

23Dr. John Walsh

The greater the temperature difference between the hot end

and cold end the greater the efficiency of the Stirling engine

The Stirling engine


24/33

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



24Dr. John Walsh

The Stirling engine


25/33

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



25Dr. John Walsh

The Stirling engine


26/33

Solar Power GenerationStirling solar units are capable of generating 25kW electricity

The Stirling engine


Applications of the Stirling engine

26Dr. John Walsh

The Stirling engine


27/33

Automobiles using Stirling enginesResearch led by General Motors and Fordnot a success

The Stirling engine



Low power to

weight ratioMore expensive

than internal

combustion engines

for same poweroutput.

Require a longer

warm up time

27Dr. John Walsh

The Stirling engine


28/33

Computer chip coolingMicro-Star International Co., Ltd, Taiwan. Miniature Stirling

engine. Uses heat from the processor to cool the processor

The Stirling engine



MSI claim the engine is 70 per cent efficient

28Dr. John Walsh


29/33

The Stirling engine


30/33

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



30Dr. John Walsh


31/33

The Stirling engine


32/33

g g


Low temp. difference type Stirling engine

32Dr. John Walsh

The Stirling engine


33/33

g g


Thank You

All Questions Welcome

33

Basic principles of operation and applications

of the Stirling engine from its invention in1816 to its modern uses

Presented by: Dr. John Walsh

Stirling engine presentation.pdf

Documents

Transcript of Stirling engine presentation.pdf