Chapter hvac engineering Fundamentals: Part 1 Introduction

Equipment: Part 1
303
Air out
Water in (sprays)
Tower fill
Air in
Water out
Figure 9.15
Natural-draft cooling tower. A flow is induced by chimney and stack effect.
Water in
Air in
Air in
Fill
Water in
Air out
Water out
Figure 9.16
Cross-flow cooling tower.
Equipment: Part 1
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304
Chapter Nine
Figure 9.17
Closed-circuit cooling tower.
tion. Periodic sterilization of the water is also required to control algae
and bacterial growth.
9.6.2
Closed-circuit towers
The closed-circuit tower (Fig. 9.17) is designed to minimize corrosion
and fouling in the cooling water circuit by making this a closed circuit.
The cooling water flows through a bare tube coil in the tower, and
coolant water in a separate circuit is sprayed over the coil and evap-
orated. This is essentially the same system as the evaporative con-
denser previously described. The coolant water circuit is open and
needs treatment and blowdown. Because of the temperature differ-
ential through the tube wall, this system is slightly less efficient than
the open-circuit tower, but the lower fouling effect improves the per-
Equipment: Part 1
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