6-1: Thermal Energy on the Move
- Thermal energy can be transferred by conduction, convection,
and radiation. Unlike radiation, conduction and convection can occur
only when matter is present.
- Conduction is heat transfer by direct contact.
- Convection is heat transfer using a fluid/gas.
- Radiation is heat transfer through space as electromagnetic
waves.
- Conductors allow heat to flow easily.
- Insulators resist heat flow.
6-2: Using Heat to Stay Warm
- A radiator is a device with a large surface area designed
to heat the air near it by conduction.
- Heating systems are generally identified by the medium
that transfers the thermal energy.
- The three most common media are hot water, steam, and
air.
- Solar energy comes from the sun (in the form of heat
and/or light).
- A solar heating system converts radiant energy from
the sun to thermal energy.
- Passive solar systems do not have devices to transfer
heat from one part of the system to another.
- Active solar systems use fans or pumps to serve this
purpose.
6-3: Using Heat to Do Work
- Heat engines are devices that convert thermal energy
produced by burning fuel into mechanical energy.
- In an internal combustion engine, fuel is burned inside
the engine.
- In an external combustion engine, fuel is burned outside
the engine.
- Heat movers move thermal energy from one place and
release it in another place.
- Sweating helps humans cool their bodies through evaporation.
6-4: Energy from the Oceans
- Differences in ocean temperatures can be used to operate
a heat engine. The process is called ocean thermal energy conversion
(OTEC).
- Additional research needs to be done to improved
the efficiency and evaluate the environmental effects of OTEC.
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