Heat Transfer

A process stream of dilute aqueous solution flowing at the rate of10 Kg.s-1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s-1. A 1 – 1 shell and tube heat exchanger is available. The best arrangement is

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Question: A process stream of dilute aqueous solution flowing at the rate of10 Kg.s-1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s-1. A 1 – 1 shell and tube heat exchanger is available. The best arrangement is
[A].

counter flow with process stream on shell side.

[B].

counter flow with process stream on tube side.

[C].

parallel flow with process stream on shell side.

[D].

parallel flow with process stream on tube side.

Answer: Option A

Explanation:

No answer description available for this question.

A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because

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Question: A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because
[A].

total heat transfer area of all the effects is -less than that in a single effect evaporator system.

[B].

total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect.

[C].

boiling point elevation in a single effect system is much higher than that in any effect in a multieffect system.

[D].

heat transfer co-efficient in a single effect is much lower than that in any effect in a multieffect system.

Answer: Option B

Explanation:

No answer description available for this question.

It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is

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Question: It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is
[A].

3.06 x l05

[B].

6.12 x 105

[C].

7.24 x 105

[D].

9.08 x 105

Answer: Option A

Explanation:

No answer description available for this question.

A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is

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Question: A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is
[A].

555

[B].

55.5

[C].

0.55

[D].

0.15

Answer: Option D

Explanation:

No answer description available for this question.

For a given ambient air temperature with increase in the thickness of insulation of a hot cylinderical pipe, the rate of heat loss from the surface would

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Question: For a given ambient air temperature with increase in the thickness of insulation of a hot cylinderical pipe, the rate of heat loss from the surface would
[A].

decrease

[B].

increase

[C].

first decrease and then increase

[D].

first increase and then decrease

Answer: Option D

Explanation:

No answer description available for this question.

Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is

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Question: Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
[A].

finned tube heat exchanger with air inside and steam outside.

[B].

finned tube heat exchanger with air outside and steam inside.

[C].

shell and tube heat exchanger with air inside tubes and steam on shell side.

[D].

shell and tube heat exchanger with air on shell side and steam inside tubes.

Answer: Option B

Explanation:

No answer description available for this question.

A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to

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Question: A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to
[A].

d0.8

[B].

d-0.2

[C].

d-1

[D].

d-1.8

Answer: Option B

Explanation:

No answer description available for this question.