Three Processes of Heat Transfer

Slide1Unit 2: HeatChapter 6:  “Heat is transferred from one place to another by three different processes.”

Slide2Heat transfers from a hot object to a  cold  object.

Slide41.Conduction 2. Convection 3. Radiation

Slide53 Types of Heat Transfer

Slide6Occurs when the particles in an object vibrate  in place but collide  with neighbouring particles passing kinetic energy to them.

Slide7The particles do not leave their original position.  Conduction occurs in most  solids .

Slide9Copper BottomStainless Steel Sides

Slide10Ice Packs

Slide11Occurs when warm fluids move from one place to another.  Occurs in  liquids  and gases .

Slide12When air warms,the particles gain energy, spread out, become less dense and rise. As it cools, the particles lose energy, get closer together, become more dense and sink. Convection Currents

Slide14Occurs when electromagnetic  waves carry energy from a source to another object. The object absorbs the energy of the electromagnetic wave.

Slide15There are  no  particles involved.  The waves can travel in a vacuum.

Slide17Types ofElectromagnetic Waves

Slide181. ReflectedShiny, smooth,   light-colored surfaces.

Slide192. AbsorbedDull, rough, dark-colored surfaces. Object will become warmer.

Slide203. TransmissionThe radiant energy passes through. Ex. Plastic, glass, paper, etc.

Slide21The MicrowaveReflection Transmission Absorption

Slide22The three types ofheat transfer, conduction, convection and radiation, can occur at the same time. For Example...

Slide25EnergyTransfers and Home Heating Systems

Slide26Activity 6-1D“Absorb That Energy” Page 184

Slide271. Open Fireplace Radiant heat from the fire and convection currents in the air spread the heat.

Slide282. Wood Stove Efficient radiators due to the black color.

Slide292. Electric Heaters

Slide303. Oil Furnace Air is drawn into the furnace and heated and fans would blow the warm air through the ducts into the rooms.  Water carried in a system of pipes can be used instead of air. ( Hot water radiation )

Slide31Forced-air furnace

Slide32Hot  Water Radiation

Slide334. Air to Air Heat Pump  Can be used to cool the home in the summer and heat the home in the winter. Heat is exchanged with the outside air.

Slide345. Geothermal Heat is exchanged with the ground.  In the summer, heat is pumped into the ground and in winter it is pumped up from the ground.

Slide35Geothermal

Slide366. Solar Converts light energy to electrical energy.

Slide37Solar Panels

Slide38“HeatPumps: An Alternative Way to Heat Homes”

Slide39Conductors Allow heat transfer  Ex. Metal (some metal are better than others) Insulators  “Prevents” heat transfer  Ex. Wood, plastic

Slide40CookwareCar Radiator

Slide41Animal FurSod

Slide42FibreglassThermos

Slide43ThermosThe vacuum layer has  no particles which prevents heat transfer. Note: It is impossible to create a perfect vacuum.

Slide44Heat is the energy which istransferred from hotter substances to colder substances. It is the sum total of the energies of the particles in a substance.  (Thermal energy)

Slide45HeatTemperature 2 2 4 3 1 3 2 2 5 2 1+2+3+3+2+4 +2+5+2+2 = 26J 26  ÷10 = 2.6  ˚C

Slide46The amount of heatneeded to raise the temperature of 1.00 g of the substance by 1.00 ˚C. Used to measure the amount of heat transfer.

Slide47Different materials havedifferent capacities for storing heat.  This depends on:  Molecular structure  Phase  Molecular mass  Shape  Surface area

Slide48Specific Heat Capacities

Slide49Specific Heat Capacity AnExample...

Slide50With a partner, listas many technologies that deal with the idea of temperature and heat.