Using HeatCh 13 Heat

Sec 3

Page 435

87

First Law of Thermodynamics

• Energy that is transferred as a result of work, heat, or both is conserved

This is also known as the

Law of Conservation of Energy87

Second Law of Thermodynamics

• Heat is always transferred from the warmer object to the colder one

87

Heating Systems

• Our body is a heating system– Some of the food we eat is transferred as

heat to blood moving throughout the human body

• We are Endothermic organisms• Normal body temp is 98.6° F• (Or 37 ° C)

88

Solar Heating

• Used by reptiles and other ectotherms

• Ectotherms take on the temperature of their surrounding, use basking

88

Central Heating

• Furnace burns coal, fuel oil or natural gas

• Energy released is transferred to water, steam, or air

• Then, the steam, air or hot water is moved to each room through pipes

89

Active Solar Heating

• Solar heating systems use the same principle

• Solar panels collect sun's rays to heat water,

• The water moves through tubes in the house like the other water heating method

• This may require the use of electricity to move the water through the pipes

89

Passive Solar Heating

• Requires no external source to move the energy

• Depends upon radiation and convection currents in fluids

• Extra Credit possibility :Research a method of passive solar heating and make a presentation to the class

Cooling Systems

• Wall Units

• Central Air

Usable energy decreases in all energy transfers

90

Insulation reduces undesirable energy transfers

• R-value measures the ability to reduce unwanted energy transfers

• See chart on page439– Which is the best

insulator?– Worst?

90

Internal Combustion EngineComponents of a typical,

four stroke cycle piston engine

(E) Exhaust camshaft(I) Intake camshaft(S) Spark plug(V) Valves(P) Piston(R) Connecting rod (C) Crankshaft (W) Water jacket for coolant

flow 91

Four-Stroke Cycle

• Intake

• Compression

• Power

• Exhaust