With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________ , if the conduction and radiation through the solid are negligible.

The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid )

A

$$\sqrt {\text{T}} $$

B

T

C

T^1.5

D

T³

Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant

A

Humidity

B

Velocity

C

Temperature

D

All of the above

During constant rate drying period, vaporisation rate per unit drying surface area

A

Decreases with time

B

Increases with time

C

Does not change with time

D

Does not affect the moisture content of the wet solid

Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate.

A

Increases

B

Decreases

C

Does not affect

D

Exponentially increases

In the constant rate period of the rate of drying curve for batch drying,

A

Cracks develop on the surface of the solid

B

Rate of drying decreases abruptly

C

Surface evaporation of unbound moisture occurs

D

None of these

During the constant rate period of drying of a solid,

A

Increased air humidity decreases the rate of drying

B

Increasing the air temperature decreases the drying rate

C

Surface evaporation of unbound moisture occurs

D

None of these

A body of mass ‘m’ moving with a constant velocity ‘v’ strikes another body of same mass moving with same velocity but in opposite direction. The common velocity of both the bodies after collision is

A

v

B

2v

C

4v

D

8v

For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same.

A

Unsaturated surface

B

Constant rate

C

Both A & B

D

Neither A nor B

At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe?

A

0.5

B

> 0.6

Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is

A

0.2

B

0.4

C

0.6

D

0.8

With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________ , if the conduction and radiation through the solid are negligible.

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