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TRG-TRC005-EN 13
period two
Condensers
notes
Common methods of modulating this water temperature include controlling the
cooling tower fans or using a cooling-tower bypass pipe. Controlling the
cooling tower fans, either by cycling fans on and off or by using a variable-
speed drive on the fans, allows the system to control the temperature of the
water leaving the tower sump. The diverting valve on the cooling-tower bypass
pipe diverts warmer water leaving the condenser and mixes it with cooler water
from the cooling tower to modulate the temperature of the water entering the
condenser.
Each of these options has the effect of varying the temperature of the water
entering the condenser, ensuring an acceptable condensing pressure and
temperature.
Another example is a system that must start and operate during cooler weather.
The cold tower water would force the condensing pressure down to the point
where the system could not operate. In this example, the temperature of the
water entering the condenser is controlled by a diverting valve and a cooling-
tower bypass pipe.
If the entering water temperature causes the condensing pressure to become
too low, the valve begins to divert the warm water that is leaving the condenser
and mixes it with the cool tower water, producing a controlled water
temperature entering the condenser. In this example, by diverting 65°F [18°C]
water leaving the condenser and mixing it with the 40°F [4°C] tower water, the
condenser is provided with 55°F [13°C] condensing water. This warmer
condensing water results in a higher condensing pressure.
condenser
condenser
bypass pipe
bypass pipe
cooling tower
cooling tower
Cooling Tower Bypass
diverting
diverting
valve
valve
40ºF
40ºF
[4ºC]
[4ºC]
65ºF
65ºF
[18ºC]
[18ºC]
55ºF
55ºF
[13ºC]
[13ºC]
Figure 20