Thermodynamics Multiple Choice Questions on “Psychrometric Chart and Process”.
1. Which of the following statement is true?
a) the chart is plotted for pressure equal to 760mm Hg
b) the constant wbt line represents adiabatic saturation process
c) the constant wbt line coincides with constant enthalpy line
d) all of the mentioned
Answer: d
Clarification: All these come from the psychrometric chart.
2. In sensible heating or cooling,
a) work done remains constant
b) dry bulb temperature or air remains constant
c) both of the mentioned
d) none of the mentioned
Answer: a
Clarification: The dry bulb temperature of air changes.
3. When humidity ratio of air ____ air is said to be dehumidified.
a) increases
b) decreases
c) remains constant
d) none of the mentioned
Answer: b
Clarification: when it increases, air is said to be humidified.
4. Air can be cooled and dehumidified by
a) circulating chilled water in tube across air flow
b) placing evaporator coil across air flow
c) spraying chilled water to air
d) all of the mentioned
Answer: d
Clarification: These are the ways of cooling and dehumidifying air.
5. Cooling and dehumidification of air is done in summer air conditioning.
a) true
b) false
Answer: a
Clarification: This is a common process in summer air conditioning.
6. Heating and humidification is done in
a) summer air conditioning
b) winter air conditioning
c) both of the mentioned
d) none of the mentioned
Answer: b
Clarification: This is opposite to summer air conditioning.
7. Which of the following is an absorbent?
a) silica gel
b) activated alumina
c) both of the mentioned
d) none of the mentioned
Answer: c
Clarification: Both of these are examples of absorbents.
8. When air passes through silica gel,
a) it absorbs water vapour molecules
b) latent heat of condensation is released
c) dbt of air increases
d) all of the mentioned
Answer: d
Clarification: This process is called chemical dehumidification.
9. In adiabatic evaporative cooling, heat transfer between chamber and surroundings is ____
a) zero
b) high
c) low
d) none of the mentioned
Answer: a
Clarification: No heat transfer takes place between chamber and surroundings in adiabatic evaporative cooling.
10. The cooling tower uses the phenomenon of evaporative cooling to cool warm water above the dbt of air.
a) true
b) false
Answer: b
Clarification: The cooling tower uses the phenomenon of evaporative cooling to cool warm water below the dbt of air.
11. Cooling towers are rated in terms of
a) approach
b) range
c) both of the mentioned
d) none of the mentioned
Answer: c
Clarification: These are the two factors considered.