Chapter 131

Question 0

Relative humidity:
A) increases when the air temperature is raised without the addition of moisture to the air
B) remains the same when the air temperature is raised
C) decreases when the air temperature is raised without the addition of moisture to the air
D) remains the same when the air temperature is lowered
E) decreases when the air temperature is lowered without the addition of moisture to the air

Answer 0

C) decreases when the air temperature is raised without the addition of moisture to the air

Question 1

The outside temperature of -25C is saturated (air at -25C holds a maximum of 0.0005 kg of moisture/kg of water). This air is drawn into the building and heated to 21C (air at 21C holds a maximum of 0.015 kg of moisture/kg of water). What is the relative humidity of the air inside?

Answer 1

3.33%

0. 0005 / 0.015 = 0.0333
1. 0333 X 100 = 3.33%

Question 2

Steam grid humidifiers used in air conditioning systems achieve humidification by:
A) the installation of a steam coil in the entering air system
B) the installation of a water coil in the entering air system
C) injecting steam in the supply air stream
D) injecting steam into the spray water of an air washer
E) injecting steam directly into the rooms to be humidified

Answer 2

C) injecting steam into the supply air stream

Question 3

Which of the following options is used to control the temperature of the spray water in an air washer?
A) only part of the spray water is recirculated and hot or cold water is added as needed
B) the spray water is recirculated through a heat exchanger and is either heated or cooled by hot or chilled water
C) heating or cooling coil is directly mounted in the sump of the water
D) all of the above

Answer 3

D) all of the above