Chapter 21 Cooling Towers

Question 1

1. During the operation of a forced draft cooling tower, which of these is NOT true?
   A. A fan forces air at a low velocity through the packing
   B. Vibration and noise are at a maximum
   C. Water flows downward
   D. Water entrained in the air is removed by the drift eliminators
   E. The fans handle mostly dry air

Answer 1

B. Vibration and noise are at a maximum

Question 2

2. Possible operational problems with natural draft cooling towers may include all of
   the following except:
   A. High discharge water temperature from the tower
   B. Reduction in water flow
   C. Low discharge water temperature from the tower
   D. Tower basin or sump overflowing
   E. Excessive water drift

Answer 2

C. Low discharge water temperature from the tower

Question 3

3. A monthly inspection of a natural draft cooling tower should include all of the
   following except:
   A. Cleaning the louvres, piping, and nozzles
   B. Checking the atmospheric wet bulb temperature
   C. Cleaning the water basin and checking for leaks
   D. Cleaning the suction screen
   E. Checking that the float control valve is operating properly

Answer 3

B. Checking the atmospheric wet bulb temperature

Question 4

4. The induced draft cooling tower has one or more fans located at the top of the
   tower that _____ the downward flow of water.
   A. Draw air upwards with
   B. Draw air downwards against
   C. Draw air upwards against
   D. Draw water upwards against
   E. Draw water upwards with

Answer 4

C. Draw air upwards against

Question 5

5. The sides of atmospheric natural draft towers are \_\_\_\_\_ and airflows across the
tower by natural currents.
A. Louvred
B. Lowered
C. Sealed
D. Slanted
E. Solid

Answer 5

A. Louvred

Question 6

6. The water to be cooled is distributed in the tower by spray nozzles and splash bars
   to expose a very _____ surface area to atmospheric air thus aiding evaporation.
   A. Large air
   B. Small water
   C. Large water
   D. Small air
   E. Wet water

Answer 6

C. Large water

Question 7

7. The actual transfer of heat in a cooling tower is accomplished by a sensible heat
   transfer (heating the air passing through the tower), and by the removal of latent
   heat as a result of the evaporation of about _____ of the water.
   A. 2%
   B. 5%
   C. 15%
   D. 10%
   E. 8%

Answer 7

B. 5%

Question 8

8. The advantages of the venturi induced draft cooling tower include all of the
   following except:
   A. Its quietness of operation
   B. The absence of any moving parts
   C. The elimination of the need for electrical connections
   D. The elimination of fill
   E. Its quiet fan operation

Answer 8

E. Its quiet fan operation

Question 9

9. The counterflow mechanical draft tower occupies less floor space than a crossflow
tower but is \_\_\_\_\_ for a given capacity.
A. Smaller
B. Shorter
C. Larger
D. Taller
E. Faster

Answer 9

D. Taller

Question 10

10.During cold weather operation what water basin temperature is required prior to
allowing full water flow over the cooling tower fill?
A. 27°C (81°F)
B. 15°C (59°F)
C. 10°C (50°F)
D. 20°C (68°F)
E. 32°C (90°F)

Answer 10

A. 27°C (81°F)

Question 11

11.Cooling towers are unquestionably the most common type of heat exchanger used
when cooling water is scarce, expensive, and a temperature within _____ of the
ambient wet bulb temperature is required.
A. 27°C to 29°C (81°F to 85°F)
B. 10°C to 12°C (50°F to 54°F)
C. 15°C to 17°C (59°F to 63°F)
D. 4°C to 6°C (8°F to 12°F)
E. 20°C to 22°C (68°F to 72°F)

Answer 11

D. 4°C to 6°C (8°F to 12°F)

Question 12

12.One of the advantages of the crossflow mechanical draft tower over the
counterflow tower is the:
A. High pressure drop in relation to its capacity
B. Low pressure drop in relation to its volume
C. High pressure drop in relation to its volume
D. Low temperature drop in relation to its capacity
E. Low pressure drop in relation to its capacity

Answer 12

E. Low pressure drop in relation to its capacity

Question 13

13.The rate of heat transfer in any cooling tower system depends on all the following
except the:
A. Relative velocity of both air and water during contact
B. Area of water surface in contact with the air
C. Length of contact time between the air and water
D. Difference between the inlet water temperature and the inlet air wet bulb
temperature
E. Atmospheric pressure

Answer 13

E. Atmospheric pressure

Question 14

14.The chimney natural draft cooling tower is also known as a \_\_\_\_\_ tower.
A. Cooling water
B. Hypergolic
C. Hyperbaric
D. Condenser
E. Hyperbolic

Answer 14

E. Hyperbolic

Question 15

15.The fans at the top of the induced draft cooling tower discharge the _____ upward
and away from the air entering at the bottom of the tower.
A. Cool, moisture-laden air
B. Hot, moisture-laden water
C. Cool, moisture-laden water
D. Hot, moisture-laden air
E. Hot, dry air

Answer 15

D. Hot, moisture-laden air

Question 16

16.Excessive water drift due to faulty drift eliminators in a cooling water tower may be
caused by all except:
A. Eliminator sections, or slats and splash retainers out of place
B. Top deck assemblies and wood till splash bars intact and level
C. Fill packs intact and in place with no sagging or gaps
D. Metering orifices in place and clean of debris
E. There must be no leaks under hot water basin sides

Answer 16

B. Top deck assemblies and wood till splash bars intact and level