MCQ Questions and Answers on Heat and Mass Transfer

Q.

The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is

A. 2.36

B. 4.36

C. 120.36

D. Depends on Reynolds number only

Discuss

Answer : Option:- B

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical

A. 0.5

B. 1

C. 1.5

D. 80

Discuss

Answer : Option:- B

Explanation :

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Q.

Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is

A. 1

B. <1

C. >1

D. >5

Discuss

Answer : Option:- B

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

The unit of heat transfer co-efficient in SI unit is

A. J/m²°K

B. W/m²°K

C. W/m°K

D. J/m°K

Discuss

Answer : Option:- B

Explanation :

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Q.

Which of the following has the lowest Prandtl number ?

A. Molten sodium (a coolant used in fast breeder reactor)

B. Water

C. Transformer oil

D. Dilute H2SO4

Discuss

Answer : Option:- A

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

At Pr >1, conduction in an ordinary fluid flowing through a heated pipe is limited to the

A. buffer zone

B. turbulent core

C. both (a) and (b)

D. viscous sub-layer

Discuss

Answer : Option:- D

Explanation :

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Q.

Heat transfer co-efficient (h1) for liquids increases with

A. increasing temperature

B. decreasing temperature

C. decreasing Reynolds number

D. none of these

Discuss

Answer : Option:- A

Explanation :

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Q.

h.D/K is called the _______ number.

A. Nusselt

B. Peclet

C. Rayleigh

D. Grashoff

Discuss

Answer : Option:- A

Explanation :

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Q.

Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

A. 32

B. 37

C. 45

D. 50

Discuss

Answer : Option:- A

Explanation :

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Q.

A pipe of diameter 10 cm is maintained at 170°C and exposed to air at 30°C. The length of the pipe is 2 m and it is kept horizontal. Find out the heat lost by the pipe per hour.

A. 705 W

B. 710 W

C. 715 W

D. 703 W

Discuss

Answer : Option:- A

Explanation :

Discuss here! No Explaination Available for These Question.

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MCQ Questions and Answers on Heat and Mass Transfer

Q. The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is

Q. At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical

Q. Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is

Q. The unit of heat transfer co-efficient in SI unit is

Q. Which of the following has the lowest Prandtl number ?

Q. At Pr >1, conduction in an ordinary fluid flowing through a heated pipe is limited to the

Q. Heat transfer co-efficient (h1) for liquids increases with

Q. h.D/K is called the _______ number.

Q. Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

Q. A pipe of diameter 10 cm is maintained at 170°C and exposed to air at 30°C. The length of the pipe is 2 m and it is kept horizontal. Find out the heat lost by the pipe per hour.

Q.

The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is

Q.

At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical

Q.

Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is

Q.

The unit of heat transfer co-efficient in SI unit is

Q.

Which of the following has the lowest Prandtl number ?

Q.

At Pr >1, conduction in an ordinary fluid flowing through a heated pipe is limited to the

Q.

Heat transfer co-efficient (h1) for liquids increases with

Q.

h.D/K is called the _______ number.

Q.

Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

Q.

A pipe of diameter 10 cm is maintained at 170°C and exposed to air at 30°C. The length of the pipe is 2 m and it is kept horizontal. Find out the heat lost by the pipe per hour.