Please take your notebook out and take your hats off

Science 14 and 10-4with Mrs. Martin

5.5 Heat Transfer Technologies

Agenda

• Review • Notes on 5.5 Heat Transfer Technologies– Liquid coolant in engines– Refrigerators

• Videos

Review

Particle Model of Matter says:–All matter is made up of small

particles.–All particles are in constant motion.

What is this jiggling or vibrating motion called?

Review

• Brownian motion is the jiggling or vibrating of particles

• As the temperature increases what happens to the movement of the particles?

• Temperature is the average of all kinetic energies (motion).

Review Give an example of:

• Convection– hot liquid or gas rises

• Conduction – direct contact heat transfer

• Radiation– travels in rays or waves

Heat Transfer Technologies

• Convection ovens use a fan to move the air in convection currents

Getting Rid of the Heat

• Engines get hot because fuel combustion releases heat

• Vehicles need to remove heat to protect the engine

• If the engine doesn’t cool properly, it overheats and explodes like this: https://www.youtube.com/watch?v=w9dED6bNIpM

Video

Coolant• Heat is conducted from the engine to the liquid

coolant, which is pumped to the radiator

Radiator• Metal alloy is a good conductor• Heat from the liquid is conducted through this

alloy to the air• Either a fan or the motion of a vehicle forces

the heat from the radiator into the air

Extra time?

• Video on how an engine works and is cooled:– https://www.youtube.com/watch?v=V7inC4lOpGs – New technology

https://www.youtube.com/watch?v=xeYPR-v_9Ko

Evaporation

• When you sweat, it is so that the water can evaporate to cool your body

• Water absorbs the heat and removes it when it evaporates into the air

• Like liquid coolant in an engine, a refrigerator uses refrigerant as coolant.

• Coolant circulates through the pipes

Refrigeration

Heat from the hot food goes to the cold refrigerator air

• The coolant evaporates as it gets warmer • It is pumped to the compressor and is

converted back to a cool liquid• The heat is released to the room

How does leaving the fridge door make the room warmer?

What happens when cooling fails?

• What happens if the electricity goes out in a nuclear power plant?– https://www.youtube.com/watch?v=91JZCbGLCvk– (short on time go to 2:55-4:15)

• Nuclear reactor meltdown from cooling malfunction on the NEWS:– https://www.youtube.com/watch?v=ulO9LOQ0yis

Quick Quiz

#2 ___________

#1 ___________

#3 ___________