Stirling EngineFacts and Technology

Marc Alessandria

Ernesto Bosque

Jobe Dyson

Kirby Little

Overview

• History

• Advantages

• Applications

• The Stirling Cycle

History• Robert Stirling; 1816• Introduced to engineering by his

father• Did not study science in school

though• Studied math and Law and

decided to become a preacher• Appointed a minister of the

Church of Scotland in 1816

History• Here he decided to invent a

new engine• His parish worked the steam

engines• Were very inefficient and often

blew up• Wanted to make his parish

lives more comfortable and safe

History• In 1816 applied for a patent for his

“Economiser”• It is the most important part of his

engine• The Economiser is responsible for

increasing the efficiency of the engine

• Sadly his engine was never utilized• It always took a back seat to

traditional engines

History• 1850; J. Ericsson• Sold nearly 2,000 engines in N. America• 1940’s; Phillips Co• Batteries became the preferred source of power

Advantages

• External Heat Source– Environmentally

friendly– Less Wear and Tear– Minimal emissions– One cycle medium

• Simple design– 2 Cylinder– No valves– Minimal maintenance

Advantage: Efficiency

• Highest thermal efficiency– Difference in temp– Full regeneration,

100% effeciency

• Combustion engines lower efficiency

Disadvantages

• Low Power to weight ratio– Impractical for motion

• Internal combustion– Practical for motion

• Production costs– No large scale

construction

USAGES OF THE STIRLING ENGINE

• Stirling Engine are used in our everyday lives.• Stirling Engine are used in refrigerators.• Liquefied gases founded in welding supply

company are made in Stirling Engine.• The satellite weather channel uses a tiny Stirling

cryo-cooler to cool the image sensor to near abolute zero.

Disadvantages to using Stirling Engines in Vehicles

• In the past 25 years, Stirling Cycling Research Group has directed it interest towards the automotive field.

• They are a couple of key characteristics why Stirling Engines are impractical for many applications, including most cars and trucks.

• Since the heat source is external, it will take a longer time for the engine to respond to the changes in the amount of heat that is applied to the cylinder.

Con’t

• In other words, the engine needs to warm up to obtain and produce the useful power.

• The engine can not change its power output quickly.

Stirling Engines in Aviation

• The main reasons these engines are needed in Aviation is because their motor is silent. Smooth torque and lack of vibrations.

• Aviation is the last major user of leaded fuel, Stirling Engines produce less pollution.

• Altitude performance is the strong reason why these engines are needed. If a plane could hold a constant power, it could cruise twice as fast at 40,000 ft as it can at sea level.

Con’t

• As a safety precaution, the plane can also fly above the weather instead of through it.

The Stirling CycleProcess breakdown

For stirling enginewithout regenerationFor stirling engine with regeneration

The Stirling CycleMaterials used in the shop.

k = Thermal Conductivityα = Coefficient of Thermal Expansion

= Heat Conduction EquationQ -k A (dT) t dx

Stainless Stealk = 15.9 (W / m*K)α = 16E-6 (°C-1)

Brassk = 120 (W / m*K)α = 20.0E-6 (°C-1)

DisplacerCylinder

DisplacerPiston

Materials used utopia.

The Stirling Cycle

Diamond Displacer Cylinderk = 3150 (W / m-K) and Displacer Pistonα = 0.11 - 1.23E-6 (°C-1)Cp= 520 (J / kg-K)

Coating of portion of k = 10 (W / m-K) Diamond Cylinder directly

above flame.

Q -k A (dT) t dx

=

Materials used utopia.

The Stirling Cycle

η = 1 - TC

TH

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