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Demos Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder and Temp Sensor Pasco Cylinder and Temp Sensor Bicycle Tire and Digital Bicycle Tire and Digital Thermometer Thermometer Steam Engine and generator + bulb Steam Engine and generator + bulb Stirling Engine Stirling Engine DI Water , Ethanol DI Water , Ethanol

Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

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Page 1: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

DemosDemos Shuttle Tile and OvenShuttle Tile and Oven Mohair fuzzMohair fuzz CandleCandle Fire SyringeFire Syringe Deck of CardsDeck of Cards Pasco Cylinder and Temp SensorPasco Cylinder and Temp Sensor Bicycle Tire and Digital ThermometerBicycle Tire and Digital Thermometer Steam Engine and generator + bulbSteam Engine and generator + bulb Stirling EngineStirling Engine

DI Water , EthanolDI Water , Ethanol

Page 2: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Thermodynamics, Thermodynamics, Heat Energy, and how we Heat Energy, and how we

benefit from it.benefit from it.

Page 3: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

OutlineOutline What is ThermodynamicsWhat is Thermodynamics What is Heat and temperatureWhat is Heat and temperature

DefinitionDefinition What makes Heat flow (heat transfer)What makes Heat flow (heat transfer)

Specific HeatSpecific Heat How heat flowsHow heat flows

ConductionConduction ConvectionConvection RadiationRadiation

Electromagnetic SpectrumElectromagnetic Spectrum Laws of Thermodynamics and EntropyLaws of Thermodynamics and Entropy Doing work on a FluidDoing work on a Fluid

Fire Piston - before the invention of the Match HeadFire Piston - before the invention of the Match Head Some common thermodynamic cyclesSome common thermodynamic cycles

Otto Cycle and other heat enginesOtto Cycle and other heat engines Combustion ProcessCombustion Process

StirlingStirling Refrigeration and heat pumpsRefrigeration and heat pumps

Why 100% efficiency is theoretically impossible (the Heat Tax)Why 100% efficiency is theoretically impossible (the Heat Tax) Common enginesCommon engines

Steam EngineSteam Engine Diesel EngineDiesel Engine Electric EngineElectric Engine

Page 4: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

What is Thermodynamics?What is Thermodynamics?

Thermo Thermo means “heat" and means “heat" and DynamicsDynamics relates to "movement"; in essence relates to "movement"; in essence thermodynamics studies the movement thermodynamics studies the movement of heat energy and how that energy of heat energy and how that energy makes mechanical movement (i.e. does makes mechanical movement (i.e. does work). work).

Page 5: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Thermodynamics is a science about Thermodynamics is a science about the effects of changes in the effects of changes in temperature, pressure, and volumetemperature, pressure, and volume and how these changes effect a and how these changes effect a physical system. physical system.

(e.g. a car engine, an air conditioner)(e.g. a car engine, an air conditioner)

Page 6: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

What is Heat?What is Heat?

Heat Energy is a type of kinetic energyHeat Energy is a type of kinetic energy

Heat Energy relates to Thermal Energy (or Heat Energy relates to Thermal Energy (or internal energy)internal energy)

Thermal Energy is the sum of the kinetic Thermal Energy is the sum of the kinetic energy, energy, ½ mv½ mv22 , of , of ALLALL the individual atoms in a the individual atoms in a system or object.system or object.

Heat is the energy that flowsHeat is the energy that flows from one from one object to anotherobject to another due to a temperature due to a temperature difference.difference.

Page 7: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

When Energy flows from a hot object to When Energy flows from a hot object to a cold object, the a cold object, the energy is called Heatenergy is called Heat

http://hop.concord.org/htu/htu.concepts.flow.html

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Before 1800, Heat was thought to be Before 1800, Heat was thought to be an invisible fluid that flowed between an invisible fluid that flowed between

objectsobjects Objects were thought to Objects were thought to

contain fixed quantities contain fixed quantities of heat.of heat.

Benjamin Thompson Benjamin Thompson observed that canons observed that canons bored with dull tools bored with dull tools became very hot while became very hot while those bored with sharp those bored with sharp tools did not get as hot. tools did not get as hot. The heat generated had The heat generated had nothing to do with the nothing to do with the size of the canon.size of the canon.

Thompson suggested Thompson suggested that heat came from that heat came from friction (or mechanical friction (or mechanical energy).energy).

http://honolulu.hawaii.edu

Page 9: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

James Joule tests the predictions:James Joule tests the predictions:

http://www.geocities.com/bioelectrochemistry/joule.htm

James Joule’s experiment proved that heat was a form of energy. In this experiment the kinetic energy of the paddle is transferred to thermal energy in the water, as measured with a sensitive thermometer.

Page 10: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Fast moving atoms with a lot of random motion collide with slower moving atoms.

As kinetic energy is transferred from the fast moving atoms to the slower moving atoms, we say that the warmer side gave up heat to the colder side and that heat was transferred.

http://hop.concord.org/htu/htu.concepts.flow.html

Two objects in contact on a microscopic Two objects in contact on a microscopic level:level:

Fast movingSlow

moving

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What is Temperature?What is Temperature?

Temperature is a measurement of the Temperature is a measurement of the average average thermal energythermal energy of the particles in a substance. of the particles in a substance.

Heat flows due to temperature differences.Heat flows due to temperature differences.

No heat is transferred between two objects that are No heat is transferred between two objects that are at the same temperature (i.e. in thermal at the same temperature (i.e. in thermal equilibrium).equilibrium).

A cup of boiling water is at the same temperature A cup of boiling water is at the same temperature as a gallon of boiling water, but the gallon of boiling as a gallon of boiling water, but the gallon of boiling water has more thermal energy than the cup.water has more thermal energy than the cup.

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Which object has higher thermal Which object has higher thermal energy?energy?

http://picasaweb.google.com/peppermint.patti1960

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Heat CapacityHeat Capacity

Heat Capacity of an object is the Heat Capacity of an object is the required energy needed to raise the required energy needed to raise the object’s temperature by one degree.object’s temperature by one degree.

A large quantity of matter has a larger A large quantity of matter has a larger heat capacity than something smallerheat capacity than something smaller

Our oceans and atmosphere have large Our oceans and atmosphere have large heat capacities due to their large sizes.heat capacities due to their large sizes.

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Specific HeatSpecific Heat

The measure of the The measure of the heat energy required to required to increase the increase the temperature of a of a unit quantity of a substance by one degree.of a substance by one degree.

CopperCopper 0.385 Joule/gr 0.385 Joule/gr ooCC

Dry AirDry Air 1.0035 Joule/gr 1.0035 Joule/gr ooCC

Humid AirHumid Air 1.0102 Joule/gr 1.0102 Joule/gr ooCC

WaterWater 4.1813 Joule/gr 4.1813 Joule/gr ooC C

Concrete Concrete 0.88 Joule/gr 0.88 Joule/gr ooCC

SandSand 0.42 Joule/gr 0.42 Joule/gr ooCC

Second highest specific heat, next to Ammonia

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Specific Heat of WaterSpecific Heat of Water

Very highVery high Earth’s ocean store vast amounts of Earth’s ocean store vast amounts of

thermal energy – these large heat thermal energy – these large heat reservoirs regulate the earth’s reservoirs regulate the earth’s temperature.temperature.

Unfrozen lakes moderate surrounding Unfrozen lakes moderate surrounding climateclimate

Water filled walls make good thermal Water filled walls make good thermal massmass

Page 16: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Water filled walls as thermal Water filled walls as thermal massmass

http://www.energybulletin.net

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Using plant material as solar Using plant material as solar massmass

McGill University, Montreal – Solar Decathlon 2007

http://www.solardecathlon.org/

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How does Heat flow?How does Heat flow? ConductionConduction – the transfer – the transfer

of heat energy by making of heat energy by making direct contact with the direct contact with the atoms/molecules of the atoms/molecules of the hotter objecthotter object

ConvectionConvection – the transfer – the transfer of heat due to a bulk of heat due to a bulk movement of matter from movement of matter from hotter to colder areashotter to colder areas

RadiationRadiation – energy – energy transferred by transferred by electromagnetic waveselectromagnetic waves

http://www.williams.edu

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Conduction

When two objects are in direct contact, particles in the hotter object are moving faster and will collide with slower moving objects in the colder object.

When this happens, heat flows. Energy is transferred from the hot

object to the cold object.

Page 20: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Touch the wood table and then Touch the wood table and then touch the metal legs of the touch the metal legs of the

table…table…Both Objects are at the same temperature, Both Objects are at the same temperature, but the metal feels colder, why?but the metal feels colder, why?You are at a higher temperature than any You are at a higher temperature than any non-living object in the room, therefore heat non-living object in the room, therefore heat is transferred from your body to both the is transferred from your body to both the wood and the metal.wood and the metal.The metal conducts heat better than the The metal conducts heat better than the wood because there are a lot of free wood because there are a lot of free electrons in metals, therefore mobile electrons in metals, therefore mobile electrons take heat from your hand faster electrons take heat from your hand faster than wood.than wood.

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The rate of heat transfer depends on:The rate of heat transfer depends on:

1.1. The Temperature differenceThe Temperature difference

2.2. And the Thermal Conductivity of the And the Thermal Conductivity of the MaterialsMaterials

Shuttle Tile white-hot at 2300 oF

The tile is 10% pure silica fibers and 90% air. The high percentage of air makes the tiles very lightweight.

Tile has very low thermal conductivity due to trapped air and the low conductivity of long glass fibers.

http://www.answers.com/topic/space-shuttle-thermal-protection-system

Page 22: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Is air a good thermal Is air a good thermal insulator?insulator?

Thermal Insulation is the method of Thermal Insulation is the method of preventing heat from entering or escaping preventing heat from entering or escaping from a container.from a container.

Stagnant air is a good thermal insulatorStagnant air is a good thermal insulator Coats, feathers, fur, hair, fiberglass insulation, Coats, feathers, fur, hair, fiberglass insulation,

& straw bales all trap tiny pockets of air.& straw bales all trap tiny pockets of air. The ocean of air over your head helps keep The ocean of air over your head helps keep

the earth cool during the day and warm the earth cool during the day and warm during the night.during the night.

Air has high specific heat.Air has high specific heat.

Page 23: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Heat energy is transmittedby collisions from neighboring atoms/molecules.

http://www.ucar.edu/

Page 24: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

More examples of More examples of ConductionConduction

www.backpackgeartest.org

www.broadys.co.nz

Page 25: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

ConvectionConvection

Buoyancy forces cause bulk movement of the water.

www.physics.arizona.ed

Page 26: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

More examples of More examples of ConvectionConvection

www.physics.arizona.eduwww.weatherquestions.com

Rising hot air and falling cool air sets up convection cells.

Page 27: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Heat from the earth’s core causes slow moving convection cells in the earth’s mantle. The earth’s crust spreads at mid-ocean ridges by 2-3 cm per year.

http://www.incois.gov.in

Heat from the earth’s core comes from ancient energy left from earth’s formation and radioactive elements which decay and release heat.

Page 28: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Oceanic ConvectionOceanic Convection

Northern Atlantic cold water sinks. This pulls in warmer water from the Gulf Stream. This heat transfer phenomenon determines how warm or cool European climates will be.

Fresh water is less dense than salt water. As Greenland’s ice fields recede more fresh water enters the North Atlantic possibly impacting normal oceanic convection patterns.

Page 29: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Forced ConvectionForced Convection

Forced Convection is not due to the Forced Convection is not due to the natural forces of buoyancy induced natural forces of buoyancy induced by heating.by heating.

Instead, there is a external force that Instead, there is a external force that causes the fluid to convect, such as a causes the fluid to convect, such as a fan or a pump.fan or a pump.

Page 30: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Convection OvensConvection Ovens

A fan circulates the air so hot air is not trapped at the top of the oven. More cookies can be baked at one time and all will cook at the same rate.

Page 31: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Ceiling FansCeiling Fanswww.sleekhome.com

In both hot and cold weather, ceiling fans are useful for circulating air to force convection.

Rooms with high ceilings are a problem during the winter as the hot air rises and moves away from the floor area.

Page 32: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Heat Transfer from RadiationHeat Transfer from Radiation All matter that has thermal energy will All matter that has thermal energy will

emit infrared electromagnetic radiation.emit infrared electromagnetic radiation. We can feel this when we put our hands We can feel this when we put our hands

close to a fire.close to a fire. This type of heat transfer requires no This type of heat transfer requires no

medium. Electromagnetic radiation travels medium. Electromagnetic radiation travels at the speed of light through a vacuum.at the speed of light through a vacuum.

http://www.newt.comhttp://www.charlesandhudson.com

Page 33: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Infrared RadiationInfrared Radiation

All objects with All objects with thermal energy emit thermal energy emit Infrared Radiation Infrared Radiation (even ice)(even ice)

Infrared radiation is Infrared radiation is invisible to our eyes invisible to our eyes but we can feel it as but we can feel it as heatheat

Nasa.gov

Page 34: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder
Page 35: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

The Sun’s energy is transferred The Sun’s energy is transferred to earth by electromagnetic to earth by electromagnetic

waveswaves

Visible LightVisible Light Infrared radiationInfrared radiation Ultraviolet (UV)Ultraviolet (UV)

http://www.foxnews.com

Page 36: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Electromagnetic Spectrum of Electromagnetic Spectrum of WavesWaves

http://www.hermes-program.gr

Page 37: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Ionizing radiation causes matter to ionize Ionizing radiation causes matter to ionize (can rip an electron off an atom)(can rip an electron off an atom)

Ionizing radiation carries more energy Ionizing radiation carries more energy than those waves with larger wavelengths.than those waves with larger wavelengths.

The sun’s UV waves are those responsible The sun’s UV waves are those responsible for burning and skin cancer.for burning and skin cancer.

Infrared is non-ionizing radiation.Infrared is non-ionizing radiation.

Non-ionizing radiation is everywhere and Non-ionizing radiation is everywhere and is considered to not be harmful.is considered to not be harmful.

Page 38: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Laws of ThermodynamicsLaws of Thermodynamics

Zeroth Law:Zeroth Law:

If two objects are in If two objects are in thermal thermal equilibriumequilibrium with a third object, then with a third object, then they are also in thermal equilibrium they are also in thermal equilibrium with each other. with each other. Thermal equilibrium means an objects temperature, pressure, and volume are not changing.

Page 39: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

A cooling cup of coffee is NOT in thermal equilibrium with the room.

http://www.cafemakers.com

Page 40: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

If two cups of coffee are at thermal equilibrium with the room, then the two cups are in thermal equilibrium with each other.

The two cups of coffee have the same temperature.

If the two cups are put in contact with each other no heat will flow.

/www.wentapottery.com

Page 41: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

First Law of Thermodynamics:First Law of Thermodynamics:(The good news!)(The good news!)

Energy is Conserved. Energy is Conserved. Energy can not be destroyed.

In an isolated system, the total energy stays the In an isolated system, the total energy stays the same.same.

Energy can be converted from one form to another.Energy can be converted from one form to another.

Thermal Energy can be converted into another form of energy!

Page 42: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

What is Entropy?What is Entropy?

Entropy = total disorder of an Entropy = total disorder of an object/systemobject/system

Disorder is the sum of the thermal energy Disorder is the sum of the thermal energy plus the physical disorder.plus the physical disorder.

Entropy always increases with time!Entropy always increases with time!

Page 43: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Examples of increasing Examples of increasing entropyentropy

www.wiley.com

Wikipedia.com

Playing “52 pick up”

Page 44: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

+

Heat, light, ash, particulates,

gases

Direction Is possible

+

Heat, light, ash, particulates,

gases

Direction Is impossible

Page 45: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Energy flows in one directionEnergy flows in one direction – – towards a more disordered statetowards a more disordered state

Page 46: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

The Second Law of The Second Law of Thermodynamics:Thermodynamics:(The bad news!)(The bad news!)

An isolated system gets more disordered with An isolated system gets more disordered with time.time.

Entropy always increases with time.Entropy always increases with time.

Page 47: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

What does this mean to us?What does this mean to us?

It is impossible to construct an engine that It is impossible to construct an engine that converts all its thermal energy into useful converts all its thermal energy into useful work. The exhaust must be hotter than work. The exhaust must be hotter than the incoming air.the incoming air.

100% efficiency is impossible –there must 100% efficiency is impossible –there must be some unusable energy be some unusable energy because because entropy must increaseentropy must increase..

We’re going to get old and dieWe’re going to get old and die The house is going to need cleaning again!The house is going to need cleaning again!

Page 48: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Why is 100% efficiency theoretically impossible?

If machine operates in a cycle, some energy must be used to reset the machine.

Parts of machine will absorb some of the heat.

Exhaust must be hotter than incoming air, due to 2nd law. This hot exhaust represents wasted energy.

http://commons.wikimedia.org

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Doing work on a FluidDoing work on a Fluid

When a fluid is compressed, work is When a fluid is compressed, work is done on the fluid.done on the fluid.

This work/energy is converted into This work/energy is converted into thermal energy within the fluid.thermal energy within the fluid.

Each molecule has more kinetic Each molecule has more kinetic energy so the temperature of the fluid energy so the temperature of the fluid increases.increases.

Page 50: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Fire PistonFire Piston

www.grannysstore.com

As air is rapidly compressed, it can reach 400-500 degrees, allowing tinder to ignite.

The compressed air is the heat source as well as the oxygen needed to ignite the tinder.

Fire piston are thought to be prehistoric fire starting devices, used in South East Asia and South Pacific. For more info see:

http://en.wikipedia.org/wiki/Fire_piston

Page 51: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

The modern match evolved during the 1800’s. Prior to 1900, fires had to be maintained or started by creating heat through friction.

Many people used flintlock guns.

Wikipedia.com

The Bow and Drill used by Native Americans

http://wildwoodsurvival.com

Page 52: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

But fluids can do But fluids can do work on work on

surroundingssurroundings A compressed gas will experience an A compressed gas will experience an

increase in pressure (as well as an increase increase in pressure (as well as an increase in temperature if compression is fast).in temperature if compression is fast).

When a pressurized gas expands it’s thermal When a pressurized gas expands it’s thermal energy decreases because it is doing work (it energy decreases because it is doing work (it is exerting forces as it expands). is exerting forces as it expands). Ex. Air escaping from a bicycle tire feels cold.Ex. Air escaping from a bicycle tire feels cold.

Page 53: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Heat EnginesHeat Engines

A cycling machine/engine that converts A cycling machine/engine that converts thermal energy into mechanical energy thermal energy into mechanical energy (also known as work)(also known as work)

Examples:Examples:

4-stroke engine (OTTO Cycle)4-stroke engine (OTTO Cycle)

Steam EnginesSteam Engines

Stirling EngineStirling Engine

Page 54: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Combustion can be Combustion can be used to energize a used to energize a

fluid fluid

Fuel sourceFuel source OxygenOxygen HeatHeat

http://www.fs.fed.us

Page 55: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

Steam Engine invented in Steam Engine invented in 17121712

Using combustion and Using combustion and water to create steam.water to create steam.

External CombustionExternal Combustion Used to pump water, Used to pump water,

power ferries, trains, power ferries, trains, & factories.& factories.

Demand for coal risesDemand for coal rises Ushers in the Ushers in the

Industrial RevolutionIndustrial Revolution HowStuffWorks

Page 56: Demos Shuttle Tile and Oven Shuttle Tile and Oven Mohair fuzz Mohair fuzz Candle Candle Fire Syringe Fire Syringe Deck of Cards Deck of Cards Pasco Cylinder

A boiler is used to heat water to create steam. This high pressure fluid in turn does work on the pistons.

Working fluid (steam) is heated through a heat exchanger. Fuel is external to working fluid.

About 6% efficienthttp://science.howstuffworks.com/steam1.htmClick for animation

HowStuffWorks

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Coal and Steam Powered Factory

Briggs and Stratton Website

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Stirling Engine - 1816Stirling Engine - 1816

Closed Cycle – working fluid is Closed Cycle – working fluid is contained within the systemcontained within the system

Highest efficiency possibleHighest efficiency possible Higher capital costsHigher capital costs Heat Source and Heat Sink Heat Source and Heat Sink

neededneeded

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http://en.wikipedia.org/wiki/Stirling_engine

The Power Piston lags the Displacer by 90o

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Gasoline Engine - 1876- 1876

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Gasoline EnginesGasoline Engines Internal Combustion – burning Internal Combustion – burning

takes place inside the enginetakes place inside the engine Based on a four-stroke combustion Based on a four-stroke combustion

cycle called the cycle called the

Otto Cycle:Otto Cycle: IntakeIntake CompressionCompression CombustionCombustion ExhaustExhaust

http://auto.howstuffworks.com/engine1.htmClick for animation

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Diesel Engine - 1876Diesel Engine - 1876

Diesel engines do not have Diesel engines do not have spark plugs because similar to spark plugs because similar to the fire piston, the compression the fire piston, the compression of the gas and air mixture is of the gas and air mixture is great enough to automatically great enough to automatically ignite the fuel.ignite the fuel.

Gas is injected into cylinder Gas is injected into cylinder after air is compressed. This after air is compressed. This allows for greater compression, allows for greater compression, and higher efficiency.and higher efficiency.

http://auto.howstuffworks.com/diesel1.htmClick for animation

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BioDieselBioDiesel

Made from plant or animal Made from plant or animal oilsoils

Chemically treated so that Chemically treated so that BioDiesel won’t solidify at BioDiesel won’t solidify at low temperatures or clog low temperatures or clog fuel linesfuel lines

Very simply chemistryVery simply chemistry

Make Magazine Vol#3

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Efficiency of EnginesEfficiency of Engines

IC Engine is only 20-30% efficientIC Engine is only 20-30% efficient

Diesel is more efficient due to the greater Diesel is more efficient due to the greater compression rate and ability to extract more compression rate and ability to extract more work out of the fuelwork out of the fuel

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Why 100% efficiency is Why 100% efficiency is impossible?impossible?

At least some of the energy must be At least some of the energy must be passed on to heat a low-temperature passed on to heat a low-temperature energy sink energy sink

This is due to the 2This is due to the 2ndnd Law of Law of Thermodynamics – Entropy must increase!Thermodynamics – Entropy must increase!

Engine needs to be reset.Engine needs to be reset. Engine parts will absorb some of the heat Engine parts will absorb some of the heat

energy.energy.

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Early cars employed three Early cars employed three technologiestechnologies

1.1. Steam powered Steam powered

2.2. Electric battery poweredElectric battery powered

3.3. Gasoline and Diesel poweredGasoline and Diesel powered

Stanley Steam Car 1912

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Steam CarsSteam Cars

HeavyHeavy Slow to heat up Slow to heat up

and startand start Required carrying Required carrying

both fuel and both fuel and waterwater

http://www.steamcar.net/my-85.html

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First electric vehicles (EV)First electric vehicles (EV) Edison worked on battery Edison worked on battery

storage believing that storage believing that electricity would power electricity would power future carsfuture cars

In 1900, roughly a third In 1900, roughly a third of all vehicles sold are of all vehicles sold are EVs EVs

EVs were marketed to EVs were marketed to women and for urban women and for urban areasareas

Thomas Edison circa 1900

Morrison’s 4-horse power EV with a range of 50 miles.

Circa 1888

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Early electric vehiclesEarly electric vehicles

Detroit Electric Carriage - 1912

Waverley Automobile Co.

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Early Gas powered carsEarly Gas powered cars

Karl Benz was the first to commercialize a gas powered motorwagon in 1885

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Why did EVs and Steamers fade Why did EVs and Steamers fade away?away?

Gasoline and Diesel have high energy Gasoline and Diesel have high energy densitiesdensities

Oil found in TexasOil found in Texas Greatest need for cars and trucks was Greatest need for cars and trucks was

in rural areas, therefore long range in rural areas, therefore long range was needed.was needed.

Steamers too heavy on unpaved roadsSteamers too heavy on unpaved roads Gas powered cars started quicklyGas powered cars started quickly Henry Ford perfected the assembly-Henry Ford perfected the assembly-

line, making his cars the most line, making his cars the most affordableaffordable

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Why was gasoline the Why was gasoline the chosen fuel source for the chosen fuel source for the

automobile?automobile? Gasoline has 1000X the energy as an Gasoline has 1000X the energy as an

equal weight of batteries.equal weight of batteries. Gasoline has 4.5X more energy per gallon Gasoline has 4.5X more energy per gallon

than liquid hydrogen.than liquid hydrogen. Gasoline has 2X the energy of coal for the Gasoline has 2X the energy of coal for the

same weightsame weight Gas has slightly less energy per volume as Gas has slightly less energy per volume as

veggie oilveggie oil Gasoline combines with Oxygen when it Gasoline combines with Oxygen when it

burns. The Oxygen is free and does not burns. The Oxygen is free and does not have to be carried.have to be carried.

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Beaumont, Texas on Spindletop Hill

Huntington Beach 1928

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Refrigeration:Refrigeration:A vapor compression A vapor compression cyclecycle

Heat leaves the fluid, heating the kitchen floor and condensing the fluid.

Heat flows into fluid

The Evaporator

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http://physics.bu.edu

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http://www.lpappliances.com

The compressor on the bottom compresses the working fluid raising its temperature.

In the condenser coils, heat leaves the fluid and enters the room. This condenses the fluid into a liquid.

When allowed to expand, the temperature of the liquid drops dramatically. This cold fluid absorbs heat from the inside of the refrigerator, causing the fluid to evaporate and turn back into a gas.

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Which law of Thermodynamics Which law of Thermodynamics does the following video does the following video

demonstrate?demonstrate?

http://www.youtube.com/watch?v=U82eWptFxSs

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Internal Combustion vs. External Internal Combustion vs. External CombustionCombustion

Pros of ICPros of IC electric starter, so electric starter, so

easier and quick to easier and quick to start upstart up

Cons of ICCons of IC By-products of By-products of

combustion in combustion in exhaust gasesexhaust gases

Pros of ECPros of EC Fuel can be anythingFuel can be anything

Cons of ECCons of EC Slow to startSlow to start Heat exchanger Heat exchanger

neededneeded If steam is the working If steam is the working

fluid:fluid: Boiler neededBoiler needed Water freezes at Water freezes at

low temperatureslow temperatures

External Combustion – the fluid doing the work (working fluid) is heated externally.

Internal Combustion – the fluid doing the work is heated by burning a fuel internally inside a cylinder pushing down on a piston

Major Plus