Heat Transfer

Question: jH factor for heat transfer depends upon the __________ number.
[A].

Biot

[B].

Nusselt

[C].

Reynolds

[D].

Prandtl

Answer: Option C

Explanation:

No answer description available for this question.

Question: 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.

Answer: Option C

Explanation:

No answer description available for this question.

Question: Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer can not take place
[A].

between two bodies in physical contact with each other.

[B].

between two bodies not in physical contact with each other.

[C].

from one part of a body to the another part of the same body.

[D].

both ‘b’ & ‘c’

Answer: Option B

Explanation:

No answer description available for this question.

Question: Among liquids, water has a comparatively high value of thermal conductivity, due to its
[A].

low density

[B].

high viscosity

[C].

partial ionisation

[D].

dense structure

Answer: Option C

Explanation:

No answer description available for this question.

Question: Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger?
[A].

Corrosiveness & fouling characteristics

[B].

pressure

[C].

viscosity

[D].

density

Answer: Option D

Explanation:

No answer description available for this question.

Question: Extremely large or small volumes of fluids are generally best routed through the shell side of a shell and tube heat exchanger, because of the
[A].

less corrosion problems.

[B].

flexibility possible in the baffle arrangement.

[C].

low pressure drop.

[D].

high heat transfer co-efficient.

Answer: Option B

Explanation:

No answer description available for this question.

Question: A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires
[A].

less heating surface.

[B].

more space.

[C].

lower maintenance cost.

[D].

none of these.

Answer: Option B

Explanation:

No answer description available for this question.

Question: Low thermal conductivity of heat insulating materials is due to its
[A].

dense structure.

[B].

high proportion of air space.

[C].

high specific heat.

[D].

none of these.

Answer: Option B

Explanation:

No answer description available for this question.

Question: Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer.
[A].

Grashoff

[B].

Reynolds

[C].

both ‘a’ & ‘b’

[D].

Prandtl & Grashoff

Answer: Option D

Explanation:

No answer description available for this question.

Question: LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.
[A].

parallel

[B].

mixed

[C].

counterflow

[D].

same in either ‘a’, b’ or ‘c’

Answer: Option D

Explanation:

No answer description available for this question.