Heat And Mass Transfer Flashcards

1
Q

In industrial crystallization from a solution, the two phase mixture of mother liquor and crystals of al sizes, which occupies the crystallizer and is withdrawn as product is called

A

Magma

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2
Q

In practice, slow cooling maintaining a low level of supersaturation produces ______ crystals and fast cooling produces ________crystals.

A

Large, small

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3
Q

It is the process by which crystalline bodies are created within a supersaturated fluid.

A

Nucleation

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4
Q

When a solution si cooled to produce a supersaturated solution and hence to cause crystallization, the heat that must be removed is the sum of the ________ necessary to cool the solution and the heat of crystallization.

A

Sensible heat content

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5
Q

To remove all the moisture from a wet solid, it requires exposure to

A

Perfectly dry air

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6
Q

The portion of water in the wet solid that cannot be removed by the air in its contact is called

A

Equilibrium moisture content

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7
Q

Moisture contained by a substance in excess of the equilibrium moisture is called

A

Free moisture

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8
Q

When drying banana chips under the sun, the rate of drying is faster on a

A

Hot and windy day

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9
Q

The critical moisture content in case of drying indicates

A

Beginning of falling rate period

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10
Q

In drying at the falling rate period, the rate at which moisture is removed from the solid material

A

Decreases with time

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11
Q

Heat sensitive materials like certain pharmaceuticals and food stuff can be dried

A

By freeze drying

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12
Q

Evaporation is also sometimes called as

A

Water distillation

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13
Q

The concentration of glycerin from a water solution by the application of heat is

A

Evaporation

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14
Q

The total amount of evaporation an evaporator is capable of producing per unit of time

A

Capacity

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15
Q

When the pressure of the chamber is decreased, the boiling point of the solution inside the chamber will

A

Decrease

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16
Q

A heat transfer device that is normally used to liquefy vapors is

A

Condenser

17
Q

The temperature driving force in an evaporator is determined as the difference between the condensing steam temperature and

A

Boiling point of the solution

18
Q

In a country where capital is scarce and energy cost is low, which is appropriate to install?

A

Single effect evaporator

19
Q

The fresh feed enters at the coldest effect

A

Feed-backward

20
Q

In commercial practice, the areas in all effects for a multiple effect evaporator are

A

Constant

21
Q

A multiple effect evaporator ______ the steam cost.

A

Decreases

22
Q

______ of the vapor is recovered and reuse in the multiple effect evaporator.

A

Latent heat

23
Q

It is the decomposition and growth on body walls, and specially on heating surfaces, of a material undergoing an irreversible chemical reaction in the evaporator.

A

Scaling

24
Q

It is the formation of deposits other than salt or scale and maybe due to corrosion.

A

Fouling

25
Q

may always be regarded as a constant-humidity process

A

Heating of air

26
Q

Wet bulb and dry bulb temperatures become identical at

A

100% saturation curve

27
Q

Steady state temperature reached by a smal amount of liquid evaporating into alarge amount of unsaturated vapor-gas mixture is

A

Wet bulb temperature

28
Q

The degrees of fredom associated with a humidification process

A

2

29
Q

Remains constant during sensible cooling process

A

Specific humidity and partial pressure of vapor

30
Q

During sensible cooling process

A

Relative humidity decreases