Heat Transfer Operations Multiple Choice Questions on “Agitated Vessels – Design and Operations”.
1. Heat transfer in Agitated Vessels can be carried out by two methods they are ____________
a) Jacketed and Plates
b) Plates and Coils
c) Jacketed and Internal coils
d) Semi coils and Internal coils
Answer: c
Clarification: Heat Transfer in Agitated vessels is carried out by two methods either by external jackets or internal coils. Here jackets usually have lower heat transfer coefficient.
2. Which one of the following is not a type of jacket?
a) Full conventional jacket
b) Dimpled jacket
c) Coiled Jacket
d) Half-pipe jacket
Answer: c
Clarification: Jackets are usually classified as full conventional jacket, a dimpled jacket, or a half-pipe jacket, which is less useful in case of industries.
3. Which one of the following jacket is best suited for agitated vessels?
a) Full conventional jacket
b) Dimpled jacket
c) Coiled Jacket
d) Half-pipe jacket
Answer: a
Clarification: A conventional jacket is usually best suited as it covers the full wall and base surface and is very simple to construct.
4. Which jacket is used to provide better mechanical strength?
a) Full conventional jacket
b) Dimpled jacket
c) Coiled Jacket
d) Half-pipe jacket
Answer: b
Clarification: Dimpled jackets are made from light gauge metals which along with a high heat transfer rate also provide mechanical strength.
5. Which one of the following jacket is usually least preferred?
a) Full conventional jacket
b) Dimpled jacket
c) Coiled Jacket
d) Half-pipe jacket
Answer: d
Clarification: A half-pipe jacket is cheap and least used for a high pressure operation on service side. By using half-pipe jacket it will cover only limited amount of the surface.
6. Which Internal coil is the most frequently used one?
a) Full helical coils
b) Singlet Coil
c) Ringlet Coil
d) Semi helical coil
Answer: a
Clarification: A full helical coil is the one most commonly observed in industries due to the fact that it offers large surface area for heat transfer.
7. Why are full helical coils so common in industries?
a) Provides Large Surface area
b) Mechanically stable
c) Very cheap to install
d) Handles highly corrosive substances
Answer: a
Clarification: A full helical coil is the one most commonly observed in industries due to the fact that it offers large surface area for heat transfer, but the problem with it is that needs mechanical support and providing a flange is usually expensive.
8. Ringlet Coils have a disadvantage, what is it?
a) Provides Less Surface area
b) Mechanically unstable
c) Very expensive to install
d) Leaves unmixed areas
Answer: d
Clarification: Ringlet coils are cheap, provide suitable surface area, can be inserted into the vessels easily but the only disadvantage it has is that it leaves unmixed areas in the vessel.
9. When a highly corrosive and reactive substance is used in the operation we prefer to use__________
a) Full helical coils
b) Full conventional jacket
c) Ringlet Coil
d) Semi helical coil
Answer: b
Clarification: When it comes to handling corrosive substances, a jacket has the advantage that there are no extra construction materials or metal surface in contact with the process other than the vessel wall.
10. For the manufacture of pharmaceuticals, when we want to minimize contamination, we prefer to use__________
a) Full helical coils
b) Full conventional jacket
c) Ringlet Coil
d) Semi helical coil
Answer: b
Clarification: For the manufacture of pharmaceuticals, where we work with fine chemicals and performance products, a jacket minimizes contamination as there are no extra surfaces to clean unlike coils.
11. A jacket has a lower heat transfer rate and coefficient than a coil.
a) True
b) False
Answer: a
Clarification: Jackets usually have thick walls and low surface area which greatly impacts its heat transfer coefficient.
12. Which of the following is not a factor for jacketed vessel’s low heat transfer rate?
a) Thick Wall
b) Low surface Area
c) Quality of material
d) Surface not in contact with vessel
Answer: c
Clarification: The quality of material used is always high yet as we use jackets the other three options are true which leads to the overall degradation of the heat transfer rate.
13. For exothermic reactions, which setup is best suited for an agitated vessel?
a) Full conventional jacket
b) Dimpled jacket
c) Full helical coils
d) Half-pipe jacket
Answer: c
Clarification: When we are considering exothermic reactions, a jacketed vessel has the disadvantage that the area/volume ratio decreases with increasing scale, hence in this case we require a high heat transfer area which is usually provided by coils.