Heat Transfer

Question: In an extended surface heat exchanger, fluid having lower co-efficient
[A].

flows through the tube.

[B].

flows outside the tubes.

[C].

can flow either inside or outside the tubes.

[D].

should not be used as it gives very high pressure drop.

Answer: Option B

Explanation:

No answer description available for this question.

Question: A 2-4 heat exchanger involves
[A].

only counter-flow of fluids.

[B].

only parallel-flow of fluids.

[C].

both counter and parallel-flow of the fluids.

[D].

smaller pressure drop compared to 1-2 exchanger.

Answer: Option C

Explanation:

No answer description available for this question.

Question: In counter flow compared to parallel flow,
[A].

LMTD is greater.

[B].

less surface area is required for a given heat transfer rate.

[C].

both (a) and (b).

[D].

more surface area is required for a given heat transfer rate.

Answer: Option C

Explanation:

No answer description available for this question.

Question: Baffle spacing
[A].

is not the same as baffle pitch.

[B].

should be less than one fifth the diameter of the shell.

[C].

should be less than the inside diameter of the shell.

[D].

none of these.

Answer: Option C

Explanation:

The distance between the baffles is called baffle spacing. While the maximum baffle spacing is equal to the diameter of the shell, the minimum is l/5th the shell diameter.

Question: In a shell and tube heat exchanger, square pitch compared to triangular pitch
[A].

gives a higher shell side pressure drop.

[B].

gives a lower shell side pressure drop.

[C].

can pack more surface area into a shell of given diameter.

[D].

none of these.

Answer: Option B

Explanation:

No answer description available for this question.

Question: In a shell and tube heat exchanger,
[A].

the temperature drops in the two fluids and the wall are proportional to individual resistances.

[B].

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

[C].

there is no relationship between temperature drop and resistance.

[D].

the relationship is not generalised.

Answer: Option A

Explanation:

No answer description available for this question.

Question: In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid
[A].

varies directly as the area and the LMTD.

[B].

directly proportional to LMTD and inversely proportional to the area.

[C].

varies as square of the area.

[D].

none of these.

Answer: Option A

Explanation:

No answer description available for this question.

Question: Baffles in the shell side of a shell and tube heat exchanger
[A].

increase the cross-section of the shell side liquid.

[B].

force the liquid to flow parallel to the bank.

[C].

increase the shell side heat transfer co-efficient.

[D].

decrease the shell side heat transfer co-efficient.

Answer: Option C

Explanation:

No answer description available for this question.

Question: Finned tube heat exchangers
[A].

give larger area per tube.

[B].

use metal fins of low thermal conductivity.

[C].

facilitate very large temperature drop through tube wall.

[D].

are used for smaller heat load.

Answer: Option A

Explanation:

No answer description available for this question.

Question: Double pipe heat exchangers are used
[A].

when heat transfer area required is very high.

[B].

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

[C].

because it occupies less floor area.

[D].

because it is less costly.

Answer: Option B

Explanation:

No answer description available for this question.