Heat Transfer

Question: Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is
[A].

0.2

[B].

0.4

[C].

0.6

[D].

0.8

Answer: Option C

Explanation:

No answer description available for this question.

Question: ‘Fouling factor’ used in the design of a multipass shell and tube heat exchanger is a
[A].

non-dimensional factor.

[B].

factor of safety.

[C].

conversion factor for individual film heat transfer co-efficient to overall heat transfer co-efficient.

[D].

none of these.

Answer: Option B

Explanation:

No answer description available for this question.

Question: In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid
[A].

is inversely proportional to the resistance across which the drop occurs.

[B].

and the wall are proportional to individual resistances.

[C].

and the wall is not related.

[D].

none of these.

Answer: Option B

Explanation:

No answer description available for this question.

Question: Double pipe heat exchangers are preferably useful, when
[A].

high viscosity liquid is to be cooled.

[B].

requirement of heat transfer area is low.

[C].

overall heat transfer co-efficient is very high.

[D].

a corrosive liquid is to be heated.

Answer: Option B

Explanation:

No answer description available for this question.

Question: Mode of heat transfer involved in the cooling of air cooled internal combustion engine is
[A].

conduction

[B].

natural convection

[C].

forced convection

[D].

none of these

Answer: Option B

Explanation:

No answer description available for this question.

Question: If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is
[A].

1

[B].

2

[C].

1/2

[D].

4

Answer: Option B

Explanation:

No answer description available for this question.

Question: In case of evaporators, liquid entrainment results primarily due to
[A].

high vacuum in the evaporator.

[B].

high evaporation rate.

[C].

foaming of the solution.

[D].

high heat transfer rate.

Answer: Option C

Explanation:

No answer description available for this question.

Question: Leidenfrost point is a term concerned with the
[A].

condensation of the saturated vapor on a cold surface.

[B].

concentration of a corrosive solution by evaporation.

[C].

heat transfer between two highly viscous liquids.

[D].

boiling of a liquid on a hot surface.

Answer: Option D

Explanation:

No answer description available for this question.

Question: Heat transfer in the laminar sublayer in case of a liquid flowing through a pipe, is mostly by
[A].

eddies current

[B].

conduction

[C].

convection

[D].

none of these

Answer: Option B

Explanation:

No answer description available for this question.

Question: Electro-magnetic spectrum range, which is important for radiation varies from __________ microns.
[A].

1 to 100

[B].

0.5 to 50

[C].

10 to 100

[D].

100 to 1000

Answer: Option B

Explanation:

No answer description available for this question.