'Fouling factor' used in the design of a multipass shell and tube heat exchanger is a

A single pass shell and tube heat exchanger, consisting of a bundle of 100 tubes (inner diameter 25 mm and thickness 2 mm) is used for heating 28 kg/s of water from 25 degree Celsius to 75 degree Celsius with the help of a steam condensing at atmospheric pressure on the shell side with condensing heat transfer coefficient 5000 W/m2 degree. Make calculation for overall heat transfer coefficient based on the inner area. Take fouling factor on the water side to be 0.002 m2 degree/W per tube and neglect effect of fouling factor on the shell side and thermal resistance of the tube wall

A

647.46 W/m2 degree

B

747.46 W/m2 degree

C

847.46 W/m2 degree

D

947.46 W/m2 degree

Plate type heat exchangers have less surface area as compared to a similar Shell and Tube heat exchanger. A Shell and Tube Heat Exchanger of equivalent area weigh six-seven times less than a Plate Type heat exchanger.

A

True

B

False

For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it

A

Decreases the pressure drop

B

Decreases the outlet temperature of cooling medium

C

Increases the overall heat transfer coefficient

D

None of these

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

In a multipass shell and tube heat exchanger, the problem of differential expansion between the shell and tube passes is taken care of by using a

A

U-bend

B

Floating head tube sheet

C

Either A or B

D

Neither A nor B

Steam is to be condensed in a shell and tube heat exchanger, 5 m long with a shell diameter of 1 m. Cooling water is to be used for removing the heat. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same. The best arrangement is

A

Vertical heat exchanger with steam on tube side

B

Vertical heat exchanger with steam on shell side

C

Horizontal heat exchanger with steam on tube side

D

Horizontal heat exchanger with steam on shell side

In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate.

A

Increases

B

Decreases

C

Does not affect

D

May increase or decrease, depends on the type of baffle

In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.

A

Once

B

Twice

C

Thrice

D

Four times

In a counter flow heat exchanger, water flowing through a tube of 10 cm inner diameter is heated by steam condensing on the outside of the tube. The convective film coefficient on the water and steam side are estimated to be 12000 and 20000 k J/m2 hr degree. Neglecting tube thickness and its resistance to heat flow, workout the overall heat transfer coefficient for the heat exchanger

A

4500 k J/m2 hr degree

B

5500 k J/m2 hr degree

C

6500 k J/m2 hr degree

D

7500 k J/m2 hr degree

The advantage of using a 1 - 2 shell and tube heat exchanger over a 1 - 1 shell and tube heat exchanger is

A

Lower tube side pressure drop

B

Lower shell side pressure drop

C

Higher tube side heat transfer co-efficient

D

Higher shell side heat transfer co-efficient

'Fouling factor' used in the design of a multipass shell and tube heat exchanger is a

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