Section 10.3

1. Section 10.3 Using Heat

2. Heating System Heating Systems: Def. p.340. 1. Work can be done to increase temperature. • Example of this is when you rub your hands together.

3. 2. The energy from food is transferred as heat to blood moving throughout the human body. • The human body is a type of heating system because it maintains a constant temperature of 37oC or (98.6oF) irrespective of the external environmental temperature.

4. 3. Heated H2O or air transfers energy as heat in central heating systems • A central heating system has a furnace that burns coal, fuel oil or gas. The energy released in the furnace is transferred as heat to H2O, steam or air.

5. 4. Solar heating systems also use warmed air or H2O. • In solar heating systems, the main source of energy is from the sun.

6. 5. Usable energy decreases in all energy transfers. • When energy ex. in the form of heat is transferred from one place to the other, the usable energy is decreased through conduction, radiation and even convection.

7. 6. Insulation minimizes undesirable energy transfers. • Insulating materials such as glass, wood, brick help reduce the loss of energy.

8. Cooling Systems Cooling Systems: Def. p.343. • Cooling systems often use evaporation to transfer energy from these surroundings.

9. An example of a cooling system is a refrigerator and it cools with the help of a refrigerant. • Refrigerant: Def.p.344

10. Condensation • Transfers energy to the surroundings. • Condensation involves transferring energy from the vapor as heat, this is why the temperature of the air outside the refrigerator increases. • Air conditioning systems use the same process as refrigerators.

11. Heat pumps can transfer energy to or from rooms. • Heat pumps use the process of evaporation and condensation of the refrigerant to provide heating during winter and cooling during summer. • In the refrigeration cycle, there is a heat pump which helps to reverse the cooling cycle.