# Psychrometrics III - MCQs with Answers

## Psychrometrics III - MCQs with Answers

Q1. At any point on the saturation curve in psychometric chart, the dry bulb temperature is always

a. less than the corresponding wet bulb temperature
b. more than the corresponding wet bulb temperature
c. equal to the corresponding wet bulb temperature
d. cannot predict

ANSWER: c. equal to the corresponding wet bulb temperature

Q2. The moisture content lines in psychrometric chart are also called as

a. relative humidity lines
b. specific humidity lines
c. both a. and b.
d. none of the above

Q3. The horizontal line in psychrometric chart joining the change of state of air represents

a. humidification
b. sensible cooling or heating
c. sensible cooling or heating with humidification
d. sensible cooling or heating with dehumidification

ANSWER: b. sensible cooling or heating

Q4. Air at dry bulb temperature Td1 is passed through the heating coil and some amount of air is by passed unaffected and leaves with dry bulb temperature Tb2 and the temperature of heated air is Td3 (where Td2 < Td3), what is the correct formula for by pass factor (The amount of air by passed unaffected)?

a. Bypass Factor = (Td3 – Td2) / (Td3 – Td1)
b. Bypass Factor = (Td3 – Td1) / (Td3 – Td2)
c. Bypass Factor = (Td2 – Td1) / (Td2 – Td3)
d. Bypass Factor = (Td2 – Td3) / (Td2 – Td1)

ANSWER: d. Bypass Factor = (Td2 – Td3) / (Td2 – Td1)

Q5. Humidification is the process of addition moisture in air at

a. constant wet bulb temperature
b. constant dry bulb temperature
c. constant latent heat
d. none of the above

ANSWER: b. constant dry bulb temperature

Q6. What is the perfect condition for dehumidification of air?

a. air is heated above its dew point temperature
b. air is cooled up to its dew point temperature
c. air is heated below its dew point temperature
d. air is cooled below its dew point temperature

ANSWER: d. air is cooled below its dew point temperature

Q7. At 100% relative humidity, the wet bulb temperature is

a. lower than the dew point temperature
b. higher than the dew point temperature
c. equal to the dew point temperature
d. none of the above

ANSWER: c. equal to the dew point temperature

Q8. The dew point temperature is less than the wet bulb temperature for

a. saturated air
b. unsaturated air
c. both saturated and unsaturated air
d. none of the above

Q9. When,
H1 = Total heat of air entering the coil (heating or cooling)
H2 = Total heat of air leaving the coil (heating or cooling)
H3 = Total heat of air at the end of the process (humidification or dehumidification)
then, the sensible heat factor (H2 – H1) / (H3 – H1) represents the process of

a. cooling and humidification
b. cooling and dehumidification
c. heating and humidification
d. heating and dehumidification

Q10. When the rate of evaporation of water is zero, the relative humidity of the air is

a. 0%
b. 100%
c. 50%
d. unpredictable