Heat and Mass Transfer

Question 1

Evaporation is also sometimes called as

Answer 1

Water distillation

Question 2

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

Answer 2

Evaporation

Question 3

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

Answer 3

Capacity

Question 4

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

Answer 4

Decrease

Question 5

A heat transfer device that is used to liquefy vapors

Answer 5

Condenser

Question 6

The temperature driving force of an evaporator is the difference between the condensing steam temperature and

Answer 6

Boiling point of the solution (T)

Question 7

In a country where capital is scarce and energy cost is low, which is appropriate to install? Single or Multiple-Effect Evaporator?

Answer 7

Single-effect evaporator

Question 8

What is called the fresh feed that enters at the coldest effect?

Answer 8

Backward feed

Question 9

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

Answer 9

Constant

Question 10

A multiple effect evaporator ______the steam cost (increases or decreases?)

Answer 10

Decreases

Question 11

___ of the vapor is recovered and reused in the multiple effect
evaporator.

Answer 11

Latent heat

Question 12

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

Answer 12

Scaling

Question 13

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

Answer 13

Fouling

Question 14

Evaporation Chapter at Perry’s

Answer 14

Chapter 11

Question 15

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a solution, the two phase mixture of mother liquor and crystals of all sizes, which occupies the crystallizer and is withdrawn as product is called

Answer 15

Magma

Question 16

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

Answer 16

Large, small

Question 17

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

Answer 17

Nucleation

Question 18

When a solution is 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

Answer 18

Sensible heat content

Question 19

Element that is constant with heaters

Answer 19

Humidity

Question 20

Element that is constant when dealing with adiabatic dryers

Answer 20

Wet bulb temperature

Question 21

For adiabatic dryers, the exiting air always has a ___ humidity than the humidity of the entering air.

Answer 21

Greater/higher (H2 > H1 for adiabatic dryers)

Question 22

Which of the following processes may always be regarded as a constant-humidity process?
a. cooling of air
b. air conditioning
c. water-cooling in a cooling tower
d. heating of air

Answer 22

D.

Question 23

Wet bulb and dry bulb temperatures become identical at

Answer 23

100% saturation curve

Question 24

Steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapor-gas mixture is called?

Answer 24

Wet bulb temperature

Question 25

The degrees of freedom associated with a humidification process is

Answer 25

2

Question 26

Which of the following remains constant during sensible cooling process?
a. specific humidity
b. partial pressure of vapor
c. both a and b
d. neither a nor b

Answer 26

C.

Question 27

During sensible cooling process
a. relative humidity decreases
b. relative humidity increases
c. wet bulb temperature increases
d. both b and c

Answer 27

B.

Question 28

Also known as 100% relative humidity

Answer 28

Dew Point

Question 29

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

Answer 29

perfectly dry air

Question 30

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

Answer 30

Equilibrium moisture content

Question 31

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

Answer 31

Free moisture

Question 32

When drying banana chips under the sun, the rate of drying is faster on a
a. slightly breezy day
b. cloudy day
c. calm day
d. hot and windy day

Answer 32

D.

Question 33

The critical moisture content in case of drying indicates

Answer 33

Beginning of the falling-rate period

Question 34

In drying at the falling rate period, the rate at which moisture is removed from the solid material
a. increases with time
b. remains constant
c. decreases with time
d. no more drying takes place

Answer 34

C.

Question 35

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

Answer 35

Freeze-drying

Question 36

Detergent solution is dried to a powder in a

Answer 36

Spray dryer

Question 37

Calcium ammonium nitrate (a fertilizer) is dried in a

Answer 37

Rotary dryer

Question 38

Rotary dryer cannot handle

Answer 38

Sticky materials

Question 39

Another term for freeze-drying

Answer 39

Lyophilization