CLIMIA CTK 240, Operating Manual

7

CTK 240 mobile air dehumidifier

Water vapour condensation

Because the capacity for the 
maximum possible volume of 
water vapour increases as the air is 
heated, the volume of water vapour 
contained remains constant and so 
relative humidity falls.

In contrast, because the capacity for 
the maximum possible volume of 
water vapour decreases as the air is 
cooled, the volume of water vapour 
contained remains constant and so 
relative humidity increases.
If the temperature continues to 
fall, the capacity for the maximum 
possible volume of water vapour 
is reduced so much so that it is 
ultimately equal to the volume of 
water vapour contained in the air.  
This temperature is referred to as 
the dew point. If the air is cooled to 
below the dew point, the volume of 
water vapour in the air will become 
greater than the maximum possible 
volume of water vapour.
At this point, the water vapour 
begins to precipitate.
This condenses to water and 
moisture is removed from the air.

Examples of condensation include 
steamed-up window panes in 
winter, or the moisture on the 
outside of a cold drinks bottle.

As the relative humidity of the air 
increases, so too does the dew 
point, making it easier for the 
temperature to fall below it.

Condensation heat

The Energy transferred to the air 
from the condenser consists of:

1.   The amount of heat derived 

beforehand in the evaporator.

2.  The electrical drive energy.

3.   The condensation heat released 

by liquefying the water vapour. 

Energy must be supplied when 
liquid is converted into a gas. This 
energy is designated as evaporation 
heat. It does not cause any increase 
in temperature, but is required 
to convert a liquid into a gas. 
Conversely, energy is released when 
gas is liquefied, this is designated as 
condensation heat. 

The amount of energy from 
evaporation heat and condensation 
heat is the same.   

For water, this is:  

2250 kJ/kg (4.18 kJ = 1kcal)

From this it is evident that the 
condensation of water vapour 
causes a large quantity of energy to 
be released.

If the moisture that it is to be 
condensed is not introduced by 
evaporation in the room itself, 
but from outside, e.g. through 
ventilation, the condensation heat 
released contributes to the heating 
of the room. With drying operations, 
a heat cycle is created, whereby 
heat is consumed for evaporation 
and released for condensation. 
When dehumidifying fed air, 
a larger contribution of heat is 
created, which manifests itself as 
a temperature increase. 

Generally speaking, the time 

required for the drying process is 

not only dependent on the output 

of the unit, but is determined to 

a greater extent by the speed at 

which the material or building 

section loses its moisture.