Active Thermal Cooling Technologies - Low Energy Cooling for Sustainable Buildings - page 147

100 2000

Measured Static model

1800

Dynamic model Ambient air

Tilted irradiance

80 1600

1400

60 1200

1000

40 800

600

20 400

200

0 0

0 60 120 180 240 300 360 420 480 540 600

Time on 27 July from 09:50 h / min

Figure 5.37 Measured and simulated air collector temperatures on a day with fast-moving clouds and
high irradiance gradients

The main assumption of a simple dehumidification model is that the sorption
isotherms, represented as a function of the relative humidity, are independent of tem-
perature and coincide. The minimum water load of the sorption material is given by
the relative humidity of the regeneration air.
The supply air humidity can then be reduced to a minimum, which is given by
the regeneration air relative humidity. Exact knowledge of the functional form of the
sorption isotherms is not necessary. For the final state of the dried air the relative
humidity, namely the regeneration humidity, is known, as well as the enthalpy

Figure 5.38 Measured dehumidification process of a silica gel sorption rotor at different regeneration
temperatures