Heat Transfer MCQ Questions & Answers | Chemical Engineering Page-7 section-3

Section 1 Section 2 Section 3 Section 4 Section 5 Section 6

61.
Grashhoff number is given by

A. gD³.β.Δtρ²/μ²

B. gD².β.Δtρ/μ²

C. gD².β.ΔtP²μ

D. gD³.β.ΔtP²/μ

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62.
In a shell and tube heat exchanger, square pitch compared to triangular pitch

A. Gives a higher shell side pressure drop

B. Gives a lower shell side pressure drop

C. Can pack more surface area into a shell of given diameter

D. Both (A) and (B)

E. Both (A) and (C)

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Answer & Solution

Answer: Option A

Solution:

In a shell and tube heat exchanger, the arrangement or spacing of the tubes within the shell can have different effects on various parameters, including pressure drop and heat transfer efficiency. Let's examine each option:

Option A: Gives a higher shell side pressure drop
This statement is generally correct. In a shell and tube heat exchanger with a square pitch arrangement, the tubes are spaced more closely together compared to a triangular pitch arrangement. The closer spacing can lead to a higher pressure drop on the shell side due to increased resistance to the flow of the fluid around the tubes.

Option B: Gives a lower shell side pressure drop
This statement is generally not correct. As mentioned earlier, the square pitch arrangement typically results in a higher pressure drop on the shell side due to the closer tube spacing.

Option C: Can pack more surface area into a shell of given diameter
This statement is generally correct. The square pitch arrangement allows for a higher density of tubes within the same shell diameter, which means more heat transfer surface area can be packed into the same space compared to a triangular pitch arrangement.

Option D: Both (A) and (B)
This option is not accurate because it suggests contradictory effects on pressure drop.

Option E: Both (A) and (C)
This option is accurate. Square pitch compared to triangular pitch can indeed result in both a higher shell side pressure drop (Option A) and the ability to pack more surface area into a shell of given diameter (Option C).

So, the correct answer is Option E: Both (A) and (C) in the context of square pitch compared to triangular pitch in a shell and tube heat exchanger.

63.
Air is best heated with steam in a heat exchanger of

A. Plate type

B. Double pipe type with fin on steam side

C. Double pipe type with fin on air side

D. Shell and tube type

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64.
An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is

A. 4000

B. 9000

C. 4600

D. 3000

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65.
Use of transverse baffles in a shell and tube heat exchanger is done to increase the

A. Rate of heat transfer

B. Flow velocity

C. Turbulence of shell side fluid

D. All of the above

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66.
Heat exchanger tubes are never made of

A. Plain carbon steel

B. Stainless steel

C. Lead

D. Copper

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67.
Which of the following has the minimum absorptivity?

A. Aluminium foil

B. Coal dust

C. Refractory bricks

D. Iron plates

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68.
The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.

A. Greater than

B. Lower than

C. Is same as

D. Half

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69.
The driving potential for the crystal growth during crystallisation is the __________ of the solution.

A. Concentration

B. Viscosity

C. Super-saturation

D. Density

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70.
For what value of Prandtl number, the Col-burn analogy is valid?

A. 0.06 to 120

B. 0.6 to 120

C. 1 to 103

D. 1 to 50

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Heat Transfer MCQ Questions & Answers | Chemical Engineering

61. Grashhoff number is given by

Answer & Solution

62. In a shell and tube heat exchanger, square pitch compared to triangular pitch

Answer & Solution

63. Air is best heated with steam in a heat exchanger of

Answer & Solution

64. An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is

Answer & Solution

65. Use of transverse baffles in a shell and tube heat exchanger is done to increase the

Answer & Solution

66. Heat exchanger tubes are never made of

Answer & Solution

67. Which of the following has the minimum absorptivity?

Answer & Solution

68. The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.

Answer & Solution

69. The driving potential for the crystal growth during crystallisation is the __________ of the solution.

Answer & Solution

70. For what value of Prandtl number, the Col-burn analogy is valid?

Answer & Solution

Read More Section(Heat Transfer)

61.
Grashhoff number is given by

62.
In a shell and tube heat exchanger, square pitch compared to triangular pitch

63.
Air is best heated with steam in a heat exchanger of

64.
An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is

65.
Use of transverse baffles in a shell and tube heat exchanger is done to increase the

66.
Heat exchanger tubes are never made of

67.
Which of the following has the minimum absorptivity?

68.
The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.

69.
The driving potential for the crystal growth during crystallisation is the __________ of the solution.

70.
For what value of Prandtl number, the Col-burn analogy is valid?