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3.14. Cooling Tower - TOWER
tower divided by the efficiency of the fan:
Ẇ f an = ∆p · ˙V air,i
η f an
(3.102)
The energy balance of the component includes the fan power (since
it must be assumed that all of the power sent into the fan will be
transformed into heat in the air):
Ḣ air,i + Ḣ w,i +Ẇ f an = Ḣ air,o + Ḣ w,o (3.103)
The variable (W Q r atio ) expresses how much power the fan consumes relative
to how big a cooling service the tower delivers to the water circuit,
since this provides an easy way to compare the power consumption to
that of commercial dry coolers.
W Q r atio =
Ẇ f an
˙Q cool
(3.104)
˙Q cool = Ḣ w,i − Ḣ w,o (3.105)
3.14.2 Wet Cooling Tower - TOWERw
The Wet Tower also has air at ambient temperature and humidity coming
in at the inlet, but since water is evaporated, the outlet temperature
of water and air is lower than for the Dry Tower (for a given ambient
temperature).
The tower is made in three steps:
1. Compression of the inlet air
2. Evaporation of water.
3. Addition of water to make up for the evaporation water loss.
1. First the fan slightly compresses the air (to produce the air flow), which
increases the pressure and temperature of the air (while the absolute
humidity is kept constant):
Ẇ f an = ∆p · ˙V air,i
η f an
(3.106)
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