MCQ Questions and Answers on Heat and Mass Transfer

Q.

What will be the heat flux across a flat board of thickness 40 mm and area 2 m² if the temperature difference across its surfaces is 30°C. Assume that the thermal conductivity of the material is 0.095 W/mK.

A. 356.3 W/m2

B. 35.63 W/m2

C. 3.563 W/m2

D. 3563 W/m2

Discuss

Answer : Option:- B

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

A mild steel ball of diameter 1.2 cm is initially at a temperature of 873 K and is exposed to air at 300 K. Find the time needed to cool the steel ball to 368 K. Assume that the convection heat transfer coefficient is 0.114 kW/m² K. Also find the heat transfer rate after 120s.

A. 2.1 min, 3.9 W

B. 2.1 min, 8.9 W

C. 2.1 min, 4.9 W

D. 2.1 min, 5.9 W

Discuss

Answer : Option:- A

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

Find the heat gain per hour by a 2 m long copper tube that is 1 cm in diameter carrying F12 at −30°C when exposed to still air at 40°C

A. 53 W

B. 54W

C. 58 W

D. 59 W

Discuss

Answer : Option:- A

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

What should be the temperature difference across a slab of thickness 1 m, having a thermal conductivity 0.1 W/m K, in order to obtain a heat flux of 3 W/m² ?

A. 0.38°C

B. 308°C

C. 380°C

D. 0.038°C

Discuss

Answer : Option:- B

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

Steam at 373K is condensed over a cylindrical surface of diameter 25 mm maintained at 357 K, heat transfer coefficient is 10864 W/m2K, the rate of heat transfer per unit length of cylinder is

A. 16.35kW/m

B. 13.65kW/m

C. 12.56kW/m

D. 15.36kW/m

Discuss

Answer : Option:- B

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

The ratio of the total emissive power of the surface to the total emissive power of the black surface at the same temperature is

A. Emissive power

B. Emissivity

C. Absorptivity

D. None of these

Discuss

Answer : Option:- B

Explanation :

The ratio of the total emissive power of the surface to the total emissive power of the black surface at the same temperature is called Emissivity.

Q.

A surface having the same value of the monochromatic hemispherical emissivity at all wavelength is a

A. Black body

B. Gray body

C. White Body

D. None of these

Discuss

Answer : Option:- B

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

Which of the following is expected to have highest thermal conductivity

A. Steam

B. Solid ice

C. Melting ice

D. Water

Discuss

Answer : Option:- B

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

Analogy between mass and heat transfer is not applicable in case of

A. same velocity profile or equal eddy diffusivities

B. thermal or pressure mass diffusion

C. viscous heating or chemical reaction

D. both (b) and (c).

Discuss

Answer : Option:- D

Explanation :

Discuss here! No Explaination Available for These Question.

Q.

Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is

A. in the central core of the fluid.

B. uniformly distributed throughout the fluid.

C. mainly confined to a thin film of fluid near the surface

D. none of these

Discuss

Answer : Option:- C

Explanation :

Discuss here! No Explaination Available for These Question.

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MCQ Questions and Answers on Heat and Mass Transfer

Q. What will be the heat flux across a flat board of thickness 40 mm and area 2 m2 if the temperature difference across its surfaces is 30°C. Assume that the thermal conductivity of the material is 0.095 W/mK.

Q. A mild steel ball of diameter 1.2 cm is initially at a temperature of 873 K and is exposed to air at 300 K. Find the time needed to cool the steel ball to 368 K. Assume that the convection heat transfer coefficient is 0.114 kW/m2 K. Also find the heat transfer rate after 120s.

Q. Find the heat gain per hour by a 2 m long copper tube that is 1 cm in diameter carrying F12 at −30°C when exposed to still air at 40°C

Q. What should be the temperature difference across a slab of thickness 1 m, having a thermal conductivity 0.1 W/m K, in order to obtain a heat flux of 3 W/m2 ?

Q. Steam at 373K is condensed over a cylindrical surface of diameter 25 mm maintained at 357 K, heat transfer coefficient is 10864 W/m2K, the rate of heat transfer per unit length of cylinder is

Q. The ratio of the total emissive power of the surface to the total emissive power of the black surface at the same temperature is

Q. A surface having the same value of the monochromatic hemispherical emissivity at all wavelength is a

Q. Which of the following is expected to have highest thermal conductivity

Q. Analogy between mass and heat transfer is not applicable in case of

Q. Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is

Q.

What will be the heat flux across a flat board of thickness 40 mm and area 2 m² if the temperature difference across its surfaces is 30°C. Assume that the thermal conductivity of the material is 0.095 W/mK.

Q.

A mild steel ball of diameter 1.2 cm is initially at a temperature of 873 K and is exposed to air at 300 K. Find the time needed to cool the steel ball to 368 K. Assume that the convection heat transfer coefficient is 0.114 kW/m² K. Also find the heat transfer rate after 120s.

Q.

Find the heat gain per hour by a 2 m long copper tube that is 1 cm in diameter carrying F12 at −30°C when exposed to still air at 40°C

Q.

What should be the temperature difference across a slab of thickness 1 m, having a thermal conductivity 0.1 W/m K, in order to obtain a heat flux of 3 W/m² ?

Q.

Steam at 373K is condensed over a cylindrical surface of diameter 25 mm maintained at 357 K, heat transfer coefficient is 10864 W/m2K, the rate of heat transfer per unit length of cylinder is

Q.

The ratio of the total emissive power of the surface to the total emissive power of the black surface at the same temperature is

Q.

A surface having the same value of the monochromatic hemispherical emissivity at all wavelength is a

Q.

Which of the following is expected to have highest thermal conductivity

Q.

Analogy between mass and heat transfer is not applicable in case of

Q.

Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is