Air-Conditioning Multiple Choice Questions on “Psychrometry – By-Pass Factor”.
1. What is the inefficiency of the coil to attain the desired temperature called?
a) By-pass factor
b) Effectiveness
c) Efficiency
d) By-pressure factor
Answer: a
Clarification: The DBT of air leaving the apparatus should be equal to the coil temperature, but this is not possible due to the inefficiency of the coil. This type of phenomenon is called a by-pass factor.
2. What is the number of fins provided in a unit length called?
a) By-pass
b) Distance
c) Pitch
d) Addendum
Answer: c
Clarification: By-pass factor depends upon the number of fins provided. So, the fins provided in a unit length are called as Pitch of the coil fins.
3. Which of the following is true about the effect of velocity on the by-pass factor?
a) decreases with an increase in velocity of air passing through it
b) remains unchanged with an increase in velocity of air passing through it
c) may increase or decrease with an increase in velocity of air passing through it depending upon the condition of air entering
d) increases with an increase in velocity of air passing through it
Answer: d
Clarification: The change in the velocity affects the temperature of leaving the air. Moreover, the inefficiency increases due to an increase in velocity as the by-pass factor increases.
4. The by-pass factor of the coil ___________ with _________ in fin spacing.
a) increases, increase
b) decreases, decrease
c) increases, decrease
d) decreases, increase
Answer: b
Clarification: One of the factors which affect the by-pass factor is fin spacing. If the fin spacing is not much, then the temperature leaving the apparatus becomes close to the coil temperature. So, the decrease in fin spacing results in a decrease in the by-pass factor by improving efficiency.
5. The by-pass factor of the coil ___________ with _________ in number of rows of fins.
a) increases, increase
b) decreases, decrease
c) increases, decrease
d) decreases, increase
Answer: d
Clarification: One of the factors which affect the by-pass factor is a number of rows of fins. More the number of rows of fins, better is the heat transfer rate and decreasing the inefficiency, i.e., by-pass factor. So, the increase in the number of rows results in a decrease in the by-pass factor by improving efficiency.
6. Which of the following does not affect the by-pass factor?
a) Pitch of the coil fins
b) Velocity of air
c) Weight of apparatus
d) Fin spacing
Answer: c
Clarification: The weight of the apparatus has nothing to do with the by-pass factor. Pitch of the coil does affect the by-pass factor. And the velocity of air as well as fin spacing affects the by-pass factor. These factors can reduce the efficiency of the process.
7. Number of rows of the fins in the opposite direction to the flow affects BPF.
a) False
b) True
Answer: a
Clarification: More the number of rows increases the heat transfer rate and decrease the by-pass factor. But these rows should be in the direction of flow to get desired results.
8. Air being passed by not being in contact with the coil known to be measured as BPF.
a) True
b) False
Answer: a
Clarification: When air flows, some of it gets in contact with the coil, and some passes directly unaffected. This by-pass process is measured as a by-pass factor and is affected by a lot of parameters.