250+ TOP MCQs on Condensers in Refrigeration and Answers

Basic Heat Transfer Operations Questions and Answers on “Condensers in Refrigeration”.

1. In a shell and coil type water cooled condenser, the refrigerant is passed through the ________
a) Coil
b) Shell
c) Tube
d) Annulus

Answer: b
Clarification: The refrigerant having lesser pressure drop is always considered to be kept at the annulus side of the double pipe setup, hence the cooling water in the inner tube as it faces larger pressure drops and in the tube side of as Shell-and-tube type setup.

2. In evaporative condensers, ___________ used to extract heat from the condensing refrigerant.
a) Air is
b) Both air and water are
c) Water is
d) Either air or water is

Answer: b
Clarification: In evaporative condensers, the two mediums undergoing evaporation and heating are water and air, hence the setup should always have water and air both simultaneously.

3. Evaporative condensers combine the features of a _____________ in a single unit.
a) Cooling tower and water-cooled condenser
b) Falling tower and water-cooled condenser
c) Cooling tower and Air condenser
d) Rising film tower and water-cooled condenser

Answer: a
Clarification: Evaporative condensers are used in places where water is scarce or limited. Since water is used in a closed setup, only a small part of the water evaporates while the rest is retained and hence the cooling towers and water-cooled condenser are used together to minimise the water loss.

4. Evaporative condensers are used in places where water is _________
a) Scarce
b) Plenty
c) Moderately available
d) Sufficient

Answer: a
Clarification: Evaporative condensers are used in places where water is scarce or limited. Since water is used in a closed setup, only a small part of the water evaporates while the rest is retained and hence the cooling towers and water-cooled condenser in a single unit are used together to minimise the water loss.

5. What is the meaning of heat rejection ratio (HRR) of a condenser?
a) Ratio of heat rejected to the heat absorbed
b) Ratio of heat absorbed to the heat rejected
c) Ratio of heat required to the heat lost
d) Ratio of heat wasted in a cycle to the heat absorbed

Answer: a
Clarification: The heat rejection ratio (abbreviated as HRR) is the ratio of the amount of heat rejected to the amount of heat absorbed (also known as refrigeration capacity), which is,
HRR = Q_c /Q_e

6. What is the relation between heat rejection ratio (HRR) and Coefficient of performance (COP)?
a) HRR = 1 + 1/COP
b) HRR = 1+ COP
c) HRR = COP/2
d) HRR = 1/COP

Answer: a
Clarification: HRR=(frac{Qc}{Qe}=frac{Qe+Wc}{Qe}=1+frac{1}{COP}) is the required relation.

7. What is the equation for Coefficient of performance of a condenser?
a) COP = Qe/Qc
b) COP = We/Qc
c) COP = Wc/Qe
d) COP = Qe/Wc

Answer: d
Clarification: The coefficient of performance is technically equal to the ratio of Heat absorbed Qe to the work done Wc.

8. The Grimson’s correlation gives the set of parameters to be used to calculate the Nusselt number for the calculation of the heat transfer coefficient as Nu = C Reⁿ Pr^0.33.
a) True
b) False