4. Definition of terms
1) Air conditioning : Keeping room air in an optimum condition, depending on the use or purpose. (Cooling, heat-
ing, humidity regulating, air cleaning, etc.)
2) Cooling (Heating) capacity : Calorie which is able to be released (or added) per a unit time in room.
It is expressed in Kcal/h, BTU/h or W.
3) Absolute humidity : The amount of vapor contained in the air. Generally it is equal to the amount of vapor by g
unit contained in 1m
3
air, and is expressed in g/m
3
.
4) Relative humidity : The ratio between the amount of vapor contained in the air and the maximum amount (the
amount of saturated vapor) of vapor capable of containing at that temperature in %.
* Relative humidity = Actual vapor pressure/Saturated vapor pressure x 100
or
= Actual vapor pressure of dew point temperature /saturated vapor pressure of dry-bulb
temp. x 100
5) Dew point temperature : The surface temperature which starts dewing on the surface when cooling a sub-
stance in the air.
6) Latent heat and sensible heat : Heat which causes a change in the state of a substance, with its temperature
constant, is called latent heat whereas heat which changes the temperature of
a substance is called sensible heat. Latent heat is expressed in terms of calo-
ries needed to cause a change of state of a substance per 1 kg. The following
equation shows that Q Kcal is needed to change state of a substance weight
G Kg when the latent heat is L Kcal/kg.
Q = GL
7) Thermal flow
(1) Radiation
: A phenomenon which thermal energy as an electro-magnetic wave is transmitted
directly from a thermal source.
(2) Conductive emission
: A phenomenon which transmits from high to low temperature when there is a
temperature difference partially in a substance.
(Example : When one tip of iron rod becomes hot.)
(3) Convection
: When the temperature of a fluid like gas or liquid changes by heat, the high tem-
perature part expands and thus the density drops to cause to be light whereas
the low temperature part is to be heavy. It means a phenomenon that heat is
transmitted together when floating happens by the weight difference of air.
Liquid
Solid
Gas
Sublimation Heat
Fusion Heat
Solidification
Heat
Condensation
Vaporization Heat
Heat
Three States of a Substance
TCL Air Conditioner Service Manual
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