Stirling Engine Facts 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 Cycle Process breakdown For stirling engine without regeneration For stirling engine with regeneration

The Stirling Cycle Materials used in the shop. k = Thermal Conductivity α = Coefficient of Thermal Expansion = Heat Conduction Equation Q -k A (dT) tdx Stainless Steal k = 15.9 (W / m*K) α = 16 E -6 (°C -1 ) Brass k = 120 (W / m*K) α = 20.0 E -6 (°C -1 ) Displacer Cylinder Displacer Piston

Materials used utopia. The Stirling Cycle DiamondDisplacer Cylinder k = 3150 (W / m-K)and Displacer Piston α = E -6 (°C -1 ) C p = 520 (J / kg-K) Coating of portion of k = 10 (W / m-K)Diamond Cylinder directly above flame. Q -k A (dT) tdx = Super Invar α = 0.72E-6 (°C-1)

Materials used utopia. The Stirling Cycle η = 1 - TCTC THTH ___