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Heat Transfer

As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the

CHEMICAL ENGINEERING, Heat Transfer /
Question: As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the
[A].

temperature of the body only.

[B].

wavelength of monochromatic radiation.

[C].

both (a) and (b).

[D].

nature of material of body.

Answer: Option A

Explanation:

No answer description available for this question.

As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the Read More »

CHEMICAL ENGINEERING, Heat Transfer

Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because

CHEMICAL ENGINEERING, Heat Transfer /
Question: Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because
[A].

convection becomes important

[B].

conduction becomes important

[C].

radiation becomes important

[D].

sub-cooled boiling occurs

Answer: Option C

Explanation:

No answer description available for this question.

Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because Read More »

CHEMICAL ENGINEERING, Heat Transfer

In sub-cooled boiling,

CHEMICAL ENGINEERING, Heat Transfer /
Question: In sub-cooled boiling,
[A].

temperature of the heating surface is less than the boiling point of the liquid.

[B].

temperature of the heating surface is more than the boiling point of the liquid.

[C].

bubbles from heating surface are absorbed by the mass of the liquid.

[D].

very large vapour space is necessary.

Answer: Option B

Explanation:

No answer description available for this question.

In sub-cooled boiling, Read More »

CHEMICAL ENGINEERING, Heat Transfer

Film boiling is usually not desired in commercial equipments, because

CHEMICAL ENGINEERING, Heat Transfer /
Question: Film boiling is usually not desired in commercial equipments, because
[A].

the heat transfer rate is low in view of the large temperature drop.

[B].

it is difficult to maintain.

[C].

it is not economic.

[D].

none of these.

Answer: Option A

Explanation:

No answer description available for this question.

Film boiling is usually not desired in commercial equipments, because Read More »

CHEMICAL ENGINEERING, Heat Transfer

All analogy equations connecting friction factor and heat transfer co-efficient apply only to

CHEMICAL ENGINEERING, Heat Transfer /
Question: All analogy equations connecting friction factor and heat transfer co-efficient apply only to
[A].

wall or skin friction

[B].

form friction

[C].

both (a) and (b)

[D].

turbulent flow

Answer: Option A

Explanation:

No answer description available for this question.

All analogy equations connecting friction factor and heat transfer co-efficient apply only to Read More »

CHEMICAL ENGINEERING, Heat Transfer

If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length

CHEMICAL ENGINEERING, Heat Transfer /
Question: If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length
[A].

ha = hl

[B].

ha = 2hl

[C].

ha = 0.5 hl

[D].

ha = 0.75 hl

Answer: Option B

Explanation:

No answer description available for this question.

If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length Read More »

CHEMICAL ENGINEERING, Heat Transfer

For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is

CHEMICAL ENGINEERING, Heat Transfer /
Question: For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is
[A].

Nu = 0.023 Re0.8 . Pr0.4

[B].

Nu = Gz

[C].

Nu = Gz

[D].

Nu = 2Gz0.5

Answer: Option C

Explanation:

No answer description available for this question.

For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is Read More »

CHEMICAL ENGINEERING, Heat Transfer