Heat Transfer MCQs

Question 1

Pick out the wrong statement.

Accepted Answer

Filmwise condensation takes place on non-wettable surfaces

Answer

Heat transfer from a hot body to cold body by the emission of heat waves is called radiation

Answer

The boiling point of a solution is affected by liquid head as well as boiling point elevation

Answer

None of these

Question 2

Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone.

Accepted Answer

Highly turbulent

Answer

Laminar

Answer

Transition

Answer

Both A & B

Question 3

At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe?

Accepted Answer

> 0.6

Answer

0.5

Answer

< 0.5

Answer

< 0.1

Question 4

Rate of heat transfer by vaporisation from pools of water is affected by the

Accepted Answer

All of the above

Answer

Nature of heating surface and distribution of bubbles

Answer

Surface tension of water

Answer

Viscosity of water

Question 5

The value of Stefan-Boltazman constant in SI unit is

Accepted Answer

5.6697 × 10-8 W/m2.°K4

Answer

0.1714 × 10-8 W/m2.°K4

Answer

5.6697 × 10-8 kcal/m2.°K4

Answer

0.1714 × 10-8 kcal/m2.°K4

Question 6

The Stefan-Boltzman constant depends on the

Accepted Answer

None of these

Answer

Medium

Answer

Temperature

Answer

Surface

Question 7

In an extended surface heat exchanger, fluid having lower co-efficient

Accepted Answer

Flows outside the tubes

Answer

Flows through the tube

Answer

Can flow either inside or outside the tubes

Answer

Should not be used as it gives very high pressure drop

Question 8

Which of the following has maximum thermal conductivity?

Accepted Answer

Iron

Answer

Coal

Answer

Nitrogen

Answer

Tar

Question 9

For specified tube outside diameter, higher BWG means higher

Accepted Answer

Cross-sectional area

Answer

Tube thickness

Answer

Weight per unit length

Answer

None of these