The ratio of down take area to cross-sectional area of the tube, for calendria type evaporator ranges from

In a vertical short tube evaporator (Calendria type), the

A

Tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylinderical drum dia of 1-6 metres are normally used

B

Area of central downtake is equal to 40 to 100% of total cross-sectional area of the surrounding tube

C

Liquor is inside the tube while the steam is outside the tube

D

All of the above

A forced circulation long tube vertical evaporator as compared to the natural circulation evaporator

A

Is economical in operation

B

Employs high velocity, high heat transfer rate and less heating surface requirement

C

Employs a centrifugal pump placed between external downtake from vapor drum and inlet to tube bundle

D

Both B & C

The ratio of tube length to shell diameter in case of liquid shell and tube heat exchanger ranges from

A

2 to 3

B

3 to 5

C

4 to 8

D

6 to 12

For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is

A

3

B

0.33

C

1

D

1.33

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

Mr. Ali decided to walk down the escalator of a tube station. He found that if he walks down 26 steps, he requires 30 seconds to reach the bottom. However, if he steps down 34 stairs he would only require 18 seconds to get to the bottom. If the time is measured from the moment the top step begins to descend to the time he steps off the last step at the bottom, find out the height of the stair way in steps?

A

23 steps

B

16 steps

C

46 steps

D

26 steps

In most of the shell and tube heat exchangers, the tube pitch is generally __________ the tube diameter.

A

Less than

B

1.25-1.50 times

C

2.5 times

D

One-fourth of

For the same diameter and thickness of tube, a water tube boiler has ________ heating surface as compared to fire tube boiler.

A

More

B

Less

C

Equal

D

None of these

Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.

A

1.25

B

1.75

C

2.5

D

3.5

For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has

A

More heating surface

B

Less heating surface

C

Equal heating surface

D

Heating surface depends on other parameters

The ratio of down take area to cross-sectional area of the tube, for calendria type evaporator ranges from

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