Heat Transfer MCQs

Question 1

Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around __________ BTU.

Accepted Answer

180

Answer

970

Answer

3.97

Answer

None of these

Question 2

Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU.

Accepted Answer

180

Answer

970

Answer

3.97

Answer

Data insufficient, can't be predicted

Question 3

When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is

Accepted Answer

Mixed convection (both free and forced)

Answer

Free convection

Answer

Entry length problem in laminar forced conduction (developing thermal boundary layer)

Answer

Forced convection

Question 4

With increase in temperature, the thermal conductivity of non-metallic amorphous solids

Accepted Answer

Increases

Answer

Decreases

Answer

Remains constant

Answer

First decreases upto certain temperature and then increases

Question 5

What is the thermal conductivity of a perfect heat insulator?

Accepted Answer

Zero

Answer

One

Answer

∞

Answer

Between 0 and ∞

Question 6

Heat transfer by radiation between two bodies at T1 & T2 and in an ambient temperature of Ta°C depends on

Accepted Answer

None of these

Answer

T1 - T2

Answer

T1 - Ta

Answer

T2 - Ta

Question 7

Which of the following is correct?

Accepted Answer

Driving force = Rate × Resistance

Answer

Rate = Driving force × Resistance

Answer

Resistance = Driving force × Rate

Answer

$${	ext{Rate}} = \frac{{{	ext{Resistance}}}}{{{	ext{Driving force}}}}$$

Question 8

Double pipe heat exchangers are used

Accepted Answer

When heat transfer area required is very low, i.e (100 - 200 ft2)

Answer

When heat transfer area required is very high

Answer

Because it occupies less floor area

Answer

Because it is less costly

Question 9

Loss of heat from untagged steam pipe to the ambient air is by

Accepted Answer

All of the above

Answer

Conduction

Answer

Convection

Answer

Radiation