Sensible Heat and Latent heat
BUCUN BENGKEL :
Sensible Heat
Heat which causes a
change in temperature of a substance is called sensible heat. When a substance
is heated and the temperature rises, the heat added is called sensible heat. Likewise,
when heat is removed from a substance and the temperature falls, the heat
removed is again, sensible heat.
Latent heat
Heat which brings
about a change of state with no change in temperature is called latent (hidden)
heat. Basically, there are four types of latent heat :
1. Latent heat of fusion – Amount of heat required to change a solid or a liquid to a solid at a constant temperature.
2. Latent heat of condensation – Amount of heat that must be removed from vapor to change it to a liquid (condensation) at a constant temperature (used in an air conditioner).
3. Latent heat of vaporization – Amount of beat that must be added to a liquid to cause it to change into a vapor (vaporization) at a constant temperature (used in an air conditioner).
4. Latent heat of sublimation – Amount of heat that must be added to a solid to change it to gas with no visible evidence of it going through the liquid state.
1. Latent heat of fusion – Amount of heat required to change a solid or a liquid to a solid at a constant temperature.
2. Latent heat of condensation – Amount of heat that must be removed from vapor to change it to a liquid (condensation) at a constant temperature (used in an air conditioner).
3. Latent heat of vaporization – Amount of beat that must be added to a liquid to cause it to change into a vapor (vaporization) at a constant temperature (used in an air conditioner).
4. Latent heat of sublimation – Amount of heat that must be added to a solid to change it to gas with no visible evidence of it going through the liquid state.
1. Temperature - heat diagram for 1 lb of water
at atmospheric pressure, heated from - 40°F through complete vaporization.
2. Temperature – heat diagram for 1 Kg of water
at atmospheric pressure, heated from -50°C through complete vaporization.
A → B – 36,3 Btu (100 KJ)
of heat were added to increase ice temperature from -40°F (-50°C) to 32°F (0°C).
– This heat is called Sensible Heat.
B → C – 144 Btu (335 KJ)
of heat were added to Melt the ice without changing its temperature. This heat is called “Latent Heat of fusion”.
C → D – 180 Btu (420KJ)
of heat were added to heat the water from 32°F (0°C) to 212°F (100°C).
– This heat is called Sensible Heat.
D → E – 970 Btu (2260 KJ)
of heat were added to convert the water to steam without changing its
temperature. – This heat is called “Latent Heat of vaporization”.
More heat increase the
temperature of steam as shown in dotted line. When cooling the steam to water,
the latent heat removed is called the “latent heat of condensation”
