REMKO ETF 400 - Manual (Page 5)

The condensation
of water vapour
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 somuch
so that it is ultimately equal to the
volume of water vapour contained
in the air.
This temperature is referred
to as"dew point". If the air
is cooled to below dew point,
the volume of water vapour
in theair will become greater than
the maximum possible volume
of water vapour.
At this point, the water vapour
begins to precipitate.
It then condenses to water. The air
is then deprived of humidity.
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 dew
point, making it easier for
the temperature to fall below it.
Building materials and structures
are capable of absorbing
considerable volumes of water,
such as brick 90-190 l/m³, heavy
concrete 140-190 l/m³ and
limestone 180-270 l/m³.
The drying of moist materials such
as masonry is effected as follows:
■ The moisture
moves from
the inside
of the material
to its surface
■ Evaporation occurs
on the surface = Transfer
of water vapour to the ambient
air
Temp. Water vapour content in g/m 3 at humidity of
°C 40% 60% 80% 100%
-5 1,3 1,9 2,6 3,3
+10 3,8 5,6 7,5 9,4
+15 5,1 7,7 10,2 12,8
+20 6,9 10,4 13,8 17,3
+25 9,2 13,8 18,4 23,0
+30 12,9 18,2 24,3 30,3
■ The air containing water vapour
is constantly circulated through
the REMKO air dehumidifier.
The air is dehumidified and,
slightly heated, leaves the unit
in order to re-absorb water
vapour.
■ In this way, the moisture
contained in the material
is reduced gradually.
The material is dried!
The accumulated condensate
is collected in the unit from where
it is drained off.
Verdampfer Kondensator
°C
30
25
20
15
% r.F.
100
90
80
70
60
50
40
30
20
10
+
+ -
Lufttemperatur
Luftfeuchte
Verlauf
Luftrichtung
As it flows through or over the evaporator, the air stream is cooled
to dew point. The water vapour condenses, and is collected
in a condensate trap from where it is drained off.
Drying materials
5