Engineering Questions with Answers - Multiple Choice Questions

# Separation Processes MCQ’s – Evaporation

1 - Question

Which of the following is a characteristic of a horizontal tube evaporator?
a) Agitation is provided only by bubbles leaving the evaporator as vapor
b) The tube bundle is arranged vertically, with the solution inside the tubes condensing outside
c) To handle viscous solution a pump is used to force liquid upwards
d) Also called short vertical tube evaporator

Explanation: Agitation is provided by the bubbles leaving the evaporator as bubbles in horizontal tube evaporator.

2 - Question

Which of the following is not an assumption in the evaporator model?
a) The feed has only one volatile components
b) Only the latent heat of vaporization is available for heating the solution
c) Boiling action in heat exchanger ensures perfect mixing
d) Overall temperature driving force is the temperature that of saturated steam

Explanation: Overall temperature driving force is not the temperature of the saturated steam. It is the difference at which the steam enters and the thick liquid concentrate leaves. Hence it is Ts-Tp.

3 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 500J
Area= 2m2
Temperature driving force is Ts-Tp 20oC
Latent heat of vaporization is Hvap=1000J
a) 2Kg
b) 3Kg
c) 20Kg
d) 30Kg

Explanation: M= UA(Ts-Tp)/Hvap, hence m= 20Kg.

4 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 500J
Area= 2m2
Temperature driving force is Ts-Tp 30oC
Latent heat of vaporization is Hvap=1000J
a) 2Kg
b) 3Kg
c) 20Kg
d) 30Kg

Explanation: M= UA(Ts-Tp)/Hvap, hence m= 30Kg.

5 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 500J
Area= 2m2
Temperature driving force is Ts-Tp 20oC
Latent heat of vaporization is Hvap=10000J
a) 2Kg
b) 3Kg
c) 20Kg
d) 30Kg

Explanation: M= UA(Ts-Tp)/Hvap, hence m= 2Kg.

6 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 500J
Area= 3m2
Temperature driving force is Ts-Tp 20oC
Latent heat of vaporization is Hvap=10000J
a) 2Kg
b) 3Kg
c) 20Kg
d) 30Kg

Explanation: M= UA(Ts-Tp)/Hvap, hence m= 3Kg.

7 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 400J
Area= 4m2
Temperature driving force is Ts-Tp 20oC
Latent heat of vaporization is Hvap=1000J
a) 32Kg
b) 36Kg
c) 58Kg
d) 65Kg

Explanation: M= UA(Ts-Tp)/Hvap, hence m= 32Kg.

8 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 300J
Area= 6m2
Temperature driving force is Ts-Tp 20oC
Latent heat of vaporization is Hvap=1000J
a) 43Kg
b) 36Kg
c) 67Kg
d) 87Kg

Explanation: M= UA(Ts-Tp)/Hvap, hence m= 36Kg.

9 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 1950J
Area= 2m2
Temperature driving force is Ts-Tp 20oC
Latent heat of vaporization is Hvap=1000J
a) 32Kg
b) 36Kg
c) 58Kg
d) 30Kg

Explanation: M= UA(Ts-Tp)/Hvap, hence m= 58Kg.

10 - Question

What is the mass flow rate of the heating steam is
Internal energy U= 400J
Area= 2m2
Temperature driving force is Ts-Tp 20oC
Latent heat of vaporization is Hvap=1000J
a) 16Kg
b) 32Kg
c) 260Kg
d) 36Kg