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Process Technology Equipment, 2e (NAPTA)
Chapter 12 Cooling Towers
1) What type of cooling tower uses temperature differences inside and outside the stack to
facilitate air movement?
A) Natural draft
B) Induced draft
C) Forced draft
D) Open draft
2) In what type of cooling tower does the working fluid pass through a heat exchange coil and
water is sprayed over it?
A) Natural draft
B) Induced draft
C) Forced draft
D) Open draft
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3) In what type of airflow in cooling towers does water flow downward and air is forced
horizontally across the water's flow path?
A) Cross-flow
B) Parallel flow
C) Counter-flow
D) Turbulent flow
4) What provides returned (hot) cooling water to a distributor box located at the top of forced
and induced draft cooling towers?
A) Fill
B) Louvers
C) Drift eliminators
D) Water distribution header
5) What prevents water from being blown out of the cooling tower?
A) Fill
B) Louvers
C) Drift eliminators
D) Water distribution header
6) What is the main purpose of the drift eliminator?
A) To minimize water loss
B) To maximize water loss
C) To replace water lost
D) To add water to the air stream
4
7) Water is an excellent cooling medium because it is _________ times more efficient at
conducting heat than air alone.
A) 10-20
B) 30-50
C) 50-100
D) 80-90
8) What is the heat load in a cooling tower that circulates 50,000 GPM with cooling water
exiting the tower at 80 degrees F and the warm cooling water returning to the tower at 100
degrees F?
A) 1,500 MBTUs/min
B) 8,330 MBTUs/min
C) 12,495 MBTUs/min
D) 13,500 MBTUs/min
5
9) A cooling tower circulates 30,000 gpm water. The hot water entering the top of the tower is
100 degrees F and is cooled to 80 degrees F by the time it enters the cooling tower basin.
Assume drift loss is 0.35% of circulation rate, evaporative losses are 1% for each 10-degree F
water temperature decrease, and blowdown rate is 0.25% of circulation rate. What is the required
makeup in GPM?
A) 75 gpm
B) 105 gpm
C) 600 gpm
D) 780 gpm
10) What is the amount of water in a given amount of air at a given temperature, compared to the
maximum amount of water that the air can hold at that same temperature?
A) Humidity
B) Dew point
C) Approach
D) Relative humidity
11) What is the moisture content in the air?
A) Humidity
B) Dew point
C) Approach
D) Relative humidity
12) When are both wet bulb and dry bulb temperatures equal?
A) When the temperature is hot
B) When the temperature is cold
C) When the humidity is low
D) When the humidity is 100%
13) What is the deterioration of a metal by a chemical reaction?
A) Scale
B) Erosion
C) Corrosion
D) Fouling
14) What occurs as a result of dissolved solids depositing on the inside surfaces of hot
equipment?
A) Scale
B) Erosion
C) Corrosion
D) Fouling
15) Which of the following can cause algae growth?
A) Circulating cooling water through a heat exchanger with ruptured tubes
B) Improper cooling tower lineup
C) Failure to treat cooling water chemically
D) Improper chemical addition to the cooling tower
16) Which of the following may cause contamination of the product?
A) Improper cooling tower lineup
B) Failure to treat cooling water chemically
C) Improper chemical addition to the cooling tower
D) Circulating cooling water through a heat exchanger with ruptured tubes
17) What is a potential problem that can result in process chemicals entering the circulating
water?
A) Tube leaks
B) Legionnaires
C) Slip hazards
D) Organic cartridges
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18) What are usually added at night when evaporation is lowest?
A) pH
B) Biocides
C) Dispersants
D) Corrosion inhibitors
19) What chemicals are added to cooling tower water to prevent corrosion in piping and heat
exchange equipment?
A) pH
B) Biocides
C) Dispersants
D) Corrosion inhibitors
20) What sounds are associated with pump cavitations?
A) Whirling sounds
B) Swishing sounds
C) Grinding sounds
D) High-pitched sounds
