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POLY ENGINEERING3-6

Power Plants

1. The engine, motor, and related parts a. Supplies the motive power of a self-propelled objectb. Produces a kinetic energy output from a fuel source

input2. Electricity generating station

a. Typically what is referred to by “power plant”b. Mechanical, heat, chemical, solar sources

Types of Power Plants

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POLY ENGINEERING3-6

Power Plants

1. Insight into the fundamental operation of most engineered technologies

2. Application of scientific and mathematical principles in real-world problem-solving situations

Why Study Power Plants?

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POLY ENGINEERING3-6

Power Plants – Engines

1. Combustion – the burning of fuel with an oxidizer2. Oxidizer – a chemical compound that transfers oxygen atoms –

a typical oxidizer is ambient air3. Ambient – surrounding, environmental, atmospheric4. External combustion engine (ECE) – heat engine that derives

heat from fuel consumed outside engine5. Internal combustion engine (ICE) – heat engine that derives

heat from combustion of fuel within engine, instead of in external furnace

6. Thermodynamics – physics that deals with the mechanical action or relations of heat

Terminology

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POLY ENGINEERING3-6

Power Plants – Engines

Types of Engines

Historically – engine referred to device that converted force into motion1) Catapult, battering ram, and other siege weapons2) Mills – grinding 3) Water mill, wind mill, horse mill, treadmill 4) al-Jazari – invented crankshaft and connecting rod, one of

the most important mech. technologies after wheel5) 1698 – first practical steam powered engine – Thomas

Savery

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POLY ENGINEERING3-6

Power Plants – Engines

Types of Engines and Uses1. External Combustion (EC) Engines:

• Steam – steam locomotives; turbines in electricity stations2. Internal Combustion (IC) Engines:

1) Four-stroke: cars, trucks, motorcycles, construction machinery, airplanes

2) Two-stroke: moped, dirt bike, chainsaw, trimmer, motor boat, lawnmowers, go-karts

3) Diesel: 50% new cars in europe, submarines, ships, locomotives, large trucks/machinery

3. Gas Turbine Engines:• Power plants and airplanes

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POLY ENGINEERING3-6

Power Plants – EnginesTypes of Engines

Reciprocating Engines:• Reciprocate: to move forward and backward

alternately• Pistons move linearly, forward and backward, in

reciprocating engines.• A crank converts linear motion into rotational

motion.

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Enginea. Steam

1) Molecules of gases are further apart than molecules in liquids and solids

2) Vaporized water (steam) takes up more space than liquid water

Types of Engines – E.C.E.

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (continued)b. History

1) 75 C.E. Hero of Alexandria – mathematician Presented plans for simple steam engine

2) 1679 Denis Papin of France – pressure cooker3) 1698 Thomas Savery, English military engineer –

Miner’s Friend pumped water out of coal mines4) 1712 Newcomen Engine, improved Savery’s

design

Types of Engines – E.C.E.

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont.)b. History (cont.)

5) 1765 James Watt (Scotland) – mathematician, inventor, instrument maker, engineerModern steam engine credited to Watt

6) 1804 Arthur Woolf (England) – compound steam engineIncreases the efficiency of the engine by reusing the steam in additional cylinders.

Types of Engines – E.C.E.

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)c. Steam Locomotive

1) 1770s – tracks laid for horses to pull carts2) 1804 – steam-powered engine3) 1820s – “Father of Railways” George

Stephenson – civil and mechanical engineer Builds first public railway linesd. Harnessing steam power made the

Industrial Revolution possible

Types of Engines – E.C.E.

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)d. Operation – PISTON

Types of Engines – E.C.E.

1) High pressure steam enters2) HP steam pushes piston3) Valve rod shifts 4) HP steam pushes piston in

reverse direction5) Original steam, now cooled,

exits through exhaust:Choo-choo-choo-choo-choo

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)d. Operation – PISTON

Types of Engines – E.C.E.

Steam ExhaustCoal Exhaust

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)d. Operation – BOILER

Types of Engines – E.C.E.

1) Coal burned in furnace2) Hot gasses boil water 3) Steam moves to cylinder,

gases exhaust through smokestack

Fire-tube Boiler (past)Water-tube Boiler (modern)

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)d. Operation – COMPOUND STEAM ENGINE

1) Engineers’ objective is to harness as much of the energy in the burning fuel as possible.

2) Compound steam engine reuses exhaust steam/fuel as much as possible (3 times below).

Types of Engines – E.C.E.

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)Types of Engines – E.C.E.

Explain what you see…

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)Types of Engines – E.C.E.

Explain what you see…

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)Types of Engines – E.C.E.

Explain what you see…

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POLY ENGINEERING3-6

Power Plants – Engines

1. Steam Engine (cont)Types of Engines – E.C.E.

Explain what you see…