Section 10.3
Using Heat
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.
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.
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.
4. Solar heating systems
also use warmed air
or H2O.
 In solar heating
systems, the main
source of energy is
from the sun.
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.
6. Insulation minimizes
undesirable energy
transfers.
 Insulating materials
such as glass, wood,
brick help reduce the
loss of energy.
Cooling Systems
Cooling Systems: Def.
p.343.
 Cooling systems often
use evaporation to
transfer energy from
these surroundings.
An example of a
cooling system is a
refrigerator and it
cools with the help of
a refrigerant.
 Refrigerant:
Def.p.344

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.




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.