CHEMICAL ENGINEERING Archives

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

CHEMICAL ENGINEERING, Heat Transfer / admin

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.

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 Read More »

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

CHEMICAL ENGINEERING, Heat Transfer / admin

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.

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 Read More »

CHEMICAL ENGINEERING, Heat Transfer

A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be

CHEMICAL ENGINEERING, Heat Transfer / admin

Question: A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be
[A].

greater than that for uninsulated steam pipe.

[B].

less than that of the uninsulated steam pipe.

[C].

equal to that of the uninsulated steam pipe.

[D].

less than the steam pipe with 5 cms insulation.

Answer: Option B

Explanation:

No answer description available for this question.

A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be Read More »

CHEMICAL ENGINEERING, Heat Transfer

If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid

CHEMICAL ENGINEERING, Heat Transfer / admin

Question: If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid
[A].

remains unchanged.

[B].

increases.

[C].

increases or decreases depending on number of shell passes.

[D].

decreases.

Answer: Option D

Explanation:

No answer description available for this question.

If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid Read More »

CHEMICAL ENGINEERING, Heat Transfer

In a laboratory test run, the rate of drying was found to be 0.5 x 10-3 kg/m2.s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry basis. A tray dryer is used to dry 100 kg (dry basis) of the same material under identical conditions. The surface area of the material is 0.04 m2/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is

CHEMICAL ENGINEERING, Heat Transfer / admin

Question: In a laboratory test run, the rate of drying was found to be 0.5 x 10-3 kg/m2.s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry basis. A tray dryer is used to dry 100 kg (dry basis) of the same material under identical conditions. The surface area of the material is 0.04 m2/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is
[A].

2000

[B].

4000

[C].

5000

[D].

6000

Answer: Option C

Explanation:

No answer description available for this question.

In a laboratory test run, the rate of drying was found to be 0.5 x 10-3 kg/m2.s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.08 on a dry basis. A tray dryer is used to dry 100 kg (dry basis) of the same material under identical conditions. The surface area of the material is 0.04 m2/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is Read More »

CHEMICAL ENGINEERING, Heat Transfer

As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient

CHEMICAL ENGINEERING, Heat Transfer / admin

Question: As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient
[A].

continues to increase.

[B].

continues to decrease.

[C].

goes through a minimum.

[D].

goes through a maximum.

Answer: Option C

Explanation:

No answer description available for this question.

As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient Read More »

CHEMICAL ENGINEERING, Heat Transfer

For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then

CHEMICAL ENGINEERING, Heat Transfer / admin

Question: For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then
[A].

hf = hd

[B].

hf > hd

[C].

hf < hd

[D].

hf could be greater or smaller than hd

Answer: Option C

Explanation:

No answer description available for this question.

For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then Read More »

CHEMICAL ENGINEERING, Heat Transfer

At steady state the temperature variation in a plane wall, made of two different solids I & II is shown below :The thermal conductivity of material I

CHEMICAL ENGINEERING, Heat Transfer / admin

Question: At steady state the temperature variation in a plane wall, made of two different solids I & II is shown below :The thermal conductivity of material I
[A].

is smaller than that of II.

[B].

is greater than that of II.

[C].

is equal to that of II.

[D].

can be greater than or smaller than that of II.

Answer: Option A

Explanation:

No answer description available for this question.

At steady state the temperature variation in a plane wall, made of two different solids I & II is shown below :The thermal conductivity of material I Read More »

CHEMICAL ENGINEERING, Heat Transfer