Chapter 70

Question 0

Natural draft cooling towers operate most effectively in large open spaces and:
A) where wind is relatively constant
B) where relative humidity is high
C) where a large body of water is nearby
D) require a windbreak
E) must not be in direct sunlight

Answer 0

A) where wind is relatively constant

Question 1

A bypass valve, which prevents water flow over the fill of a tower during cold weather, should not be closed until the water temperature reaches:
A) -1*C
B) 1*C
C) 5*C
D) 21*C
E) 27*C

Answer 1

E) 27*C

Question 2

Scaling is not as severe in towers when compared to boilers because:
A) tower water does not evaporate
B) there are not as many dissolved solids in tower water
C) pressure is not as high
D) temperatures are not as high
E) water is constantly being agitated

Answer 2

D) temperatures are not as high

Question 3

List 4 factors that affect the rate of heat transfer in a cooling tower:

Answer 3

Relative velocity of both the air and water during contact
Area of water surface in contact with the air
Length of contact time between air and water
Difference between inlet water temperature and inlet air wet bulb temperature (relative humidity)

Question 4

Cooling towers are divided into two classes according to the method of air circulation. These classes are _____ and _____.

Answer 4

Natural, mechanical

Question 5

Dissolved and suspended solids can build up in a closed cooling tower system as the water evaporates. This buildup is controlled by;
A) adding chemicals to remove the dissolved solids
B) treating the water supply to remove dissolved solids
C) scraping the scale from the cooling tower components on a regular basis
D) bleeding a portion of the water fom the system continuously

Answer 5

D) bleeding a portion of the water from the system continuously