HAM

Question 1

Which of the following equipment is used to convert the latent heat or sensible heat of a fluid into latent heat of vaporization of another fluid?

Answer 1

heat exchanger

Question 2

Specifications of condenser or heat exchanger tubes are reported as BWG number. Condenser tubes having same BWG number have same ___ regardless of nominal diameter.

Answer 2

wall thickness

Question 3

An important parameter in heat exchanger analysis, this quantity is defined as the ratio of heat exchanger’s ability to transfer heat to the fluid’s minimum ability to absorb heat.

Answer 3

NTU

Question 4

What is the prime reason of using multi-pass shell-and-tube heat exchangers?

Answer 4

higher heat transfer coefficient and shorter tubes are required

Question 5

Which of the following correctly describes a finned-tube heat exchanger?

Answer 5

large heat exchange surface per tube

Question 6

Staggered configuration of bank of tubes in heat exchanger internals has a ____ pitch

Answer 6

triangular

Question 7

The hot fluid in a concentric-tubes heat exchanger enters at 65℃ and leaves at 40℃, while cold fluid enters at 15℃ and leaves at 45℃. From the information given we can deduce that

Answer 7

the heat exchange operates in counterflow configuration

Question 8

The hot fluid in a concentric-tubes heat exchanger enters at 65℃ and leaves at 40℃, while cold fluid enters at 15℃ and leaves at 45℃. If the heat exchanger were practical, what would be its expected effectiveness?

Answer 8

0.50

Question 9

Theoretically, what is expected of a cooling tower that is designed based on approach = 0?

Answer 9

The tower is impractically high

Question 10

In cooling tower design and operating, the term range refers to the

Answer 10

difference between hot and cold water temperatures

Question 11

When will the wet-bulb temperature be equal to the dry-bulb temperature for air-water vapor systems

Answer 11

when RH = 100%

Question 12

The portion of the moisture content of a solid material that can be removed by drying using air at constant drying conditions is called

Answer 12

free-moisture content

Question 13

A measure of evaporator performance defined as the number of kg solvent vaporized per kg steam fed to the evaporator

Answer 13

economy

Question 14

The driving force in heat transfer occurring in evaporator is equal to the

Answer 14

difference between the temperature of the solution and of the steam

Question 15

In a forward-feed multiple-effect evaporator units, which of the following is true
The viscosity of the liquid is highest in the first effect
The solution is transported through effects by a pump
No pump is needed to withdraw the concentrate from the last effect
Boiling point elevation is the highest in the last effect

Answer 15

Boiling point elevation is the highest in the last effect

Question 16

Which feeding strategy in multiple-effect evaporators is most recommended to concentrate a cold viscous feed, i.e. honey?

Answer 16

backward feeding

Question 17

What is the effect of BPR in multiple-effect evaporator system?

Answer 17

reduces capacity

Question 18

Which of the following is most likely the effect of lowering the temperature of the feed to the evaporator?

Answer 18

reduced economy

Question 19

Which of the following state the Duhring’s principle?

Answer 19

The boiling point elevation of an aqueous solution is proportional to the concentration

Question 20

The solubility of anhydrous sodium sulfate in water decreases with temperature. What is the most suitable evaporator for concentrating an aqueous solution of a material like sodium sulfate?

Answer 20

vacuum evaporator

Question 21

Which of the following is an example of liquid-film-controlled absorption

Answer 21

absorption of carbon dioxide in water

Question 22

Which of the following air-conditioning processes occurs at constant dew point temperature

Answer 22

heating

Question 23

The ____ of an air-water vapor system is defined as the kg of water vapor, with partial pressure equal to its vapor pressure, contained in 1 kg of dry air.

Answer 23

saturation humidity

Question 24

For air-water vapor system at low pressures, the adiabatic saturation temperature is equal to the ____.

Answer 24

wet-bulb temperature

Question 25

A given amount of wet air is cooled at constant dew point and constant total pressure. Which of the following is not possible to occur?

Answer 25

The enthalpy of air will increase

Question 26

For air-water vapor system, when will dry-bulb temperature be equal to the wet-bulb temperature?

Answer 26

when relative humidity reaches 100%

Question 27

Why are induced-draft towers generally preferred to other intermediate-sized water-cooling towers?

Answer 27

Induced-draft towers prevent recirculation of the humidified air

Question 28

Which of the following does not occur in a water-cooling tower?

Answer 28

The humidity of the air decreases

Question 29

Which of the following list the principles involved in water-cooling towers?

Answer 29

latent heat transfer, sensible heat transfer, mass transfer, humidification

Question 30

The equilibrium curve required in the design of the water cooling tower is a plot of

Answer 30

enthalpy of the air and temperature of the water

Question 31

In the drying of a wet solid material at constant drying conditions, the total drying is the sum of the drying time in the constant-rate period and drying time in the falling-rate period if

Answer 31

the initial free-moisture content is greater than the critical free-moisture content.

Question 32

Which drying period at constant drying conditions is usually divided into two zones - the unsaturated surface drying and the internal moisture movement?

Answer 32

falling-rate period

Question 33

In some materials, the movement of moisture during drying at constant conditions in the falling-rate period is controlled by diffusion. Of the four materials listed, identify the one which most likely will not exhibit this mechanism? clay sand starch textile

Answer 33

sand

Question 34

If the rate of interphase mass transfer is high and the surface area for transfer is large, then the height of a transfer unit in the packed column is ___.

Answer 34

small

Question 35

In the design of packed columns, the diameter and the pressure drop across the packed height are estimated based on the

Answer 35

flooding velocity of the gas

Question 36

Which quantity is used as a measure of the separation effectiveness of the particular packing material for the species being processed in the packed column?

Answer 36

HTU

Question 37

Why is the triangular pitch preferred to square pitch tube layout in shell-and-tube heat exchangers?

Answer 37

It facilitates easier cleaning of external surfaces of the tubes, resulting in lower maintenance cost.

Question 38

How will the LMTD correction factor or fudge factor change as the number of shell-passes is increased in a shell-and-tube heat exchanger?

Answer 38

increase

Question 39

The simplest type of heat exchanger is the

Answer 39

double-pipe heat exchanger.

Question 40

What is the main reason for using multi-pass heat exchangers?

Answer 40

To obtain higher U and shorter tubes

Question 41

Which one characteristic is common to most heat exchangers?

Answer 41

A solid boundary separates the hot fluid and cold fluid.

Question 42

What is the major disadvantage of the double-pipe heat exchanger?

Answer 42

low heat-transfer surface

Question 43

Which type of heat exchanger do you recommend for applications which require large heat transfer surface?

Answer 43

Double-pipe heat exchanger

Question 44

In shell-and-tube heat exchangers, baffles are usually not needed if

Answer 44

condensing vapor on the shell-side serves as the heating medium.

Question 45

In shell-and-tube heat exchangers, where must the cleaner or less corrosive fluid be placed?

Answer 45

tube-side

Question 46

In shell-and-tube heat exchangers, where must a highly viscous fluid be placed?

Answer 46

tube-side

Question 47

To avoid expensive high-pressure shells in shell-and-tube heat exchangers, high-pressure fluid should flow through ___.

Answer 47

the tubes

Question 48

In a water to air heat exchanger, it is important to place fins on the air side because

Answer 48

it effects good mixing of the gas and this promotes good heat transfer.

Question 49

What is the primary purpose of installing baffles in shell-and-tube heat exchangers?

Answer 49

To increase the convection coefficient of the shell-side fluid

Question 50

The deposition of film or scale on the surface of the heat exchanger causes all of the following except: Decreased overall heat-transfer coefficient Increased resistance to heat transfer between fluids Lowered exit temperature of the cold fluid Lowered exit temperature of the hot fluid

Answer 50

Lowered exit temperature of the hot fluid

Question 51

Oil, flowing in the inner tube, is being heated by a saturated steam, condensing at 1.30 bars in the annular space of a double-pipe heat exchanger. The overall heat-transfer coefficient for this system is expected to be

Answer 51

closer to the value of oil-side heat transfer coefficient.

Question 52

The fouling factor, Rf, depends on which of the following: (a) operating temperature; (b) fluid velocity; and, (c) length of service?

Answer 52

a, b, and c

Question 52

The fouling factor, Rf, depends on which of the following: (a) operating temperature; (b) fluid velocity; and, (c) length of service?

Answer 52

a, b, and c

Question 53

Which of the following fluid combinations is expected to have the highest U?

Answer 53

Steam condenser (water in tubes)

Question 54

Which set of factors affect the value of the fudge factor, F?

Answer 54

Exit temperatures, inlet temperatures, and heat exchanger type

Question 55

The fudge factor, F, is a function of R and S. If either R or S is zero, then all of the following are (or may be) true except:

Answer 55

One fluid stream has negligible heat capacity

Question 56

Which of the following defines maximum possible heat-transfer rate?

Answer 56

qmax = Cmin(Th,i – Tc,i)

Question 57

Which of the following does not necessarily apply to boilers and condensers?

Answer 57

Cmin = 0

Question 58

In which double-pipe heat-exchanger flow configuration is the temperature driving force decreasing toward the outlet of the heat exchanger?

Answer 58

Parallel flow

Question 59

If the temperature change of either fluid in a shell-and-tube or cross-flow heat exchanger is negligible, then correction factor (fudge factor) for LMTD is ___.

Answer 59

1

Question 60

If the hot fluid stream is a condensing vapor, then Cr = Cmin/Cmax =

Answer 60

∞

Question 61

The product of mass flow rate and heat capacity is called the

Answer 61

heat capacity rate

Question 62

Extended surfaces are normally installed at the fluid side of the heat exchanger where

Answer 62

the convective coefficient is low

Question 63

Mean temperature difference (MTD) and LMTD have practically same numerical values for which of the following situations?

Answer 63

When driving force does not vary much

Question 64

Which of the following is an example of a compact heat exchanger?

Answer 64

Tube-plate heat exchanger

Question 65

The relation, NTU = -ln(1-ε), applies to all heat exchangers as long as

Answer 65

Cmin/Cmax = 0

Question 66

In tube bundles inside shell-and-tube heat exchangers, the shortest distance between adjacent tubes is called the ___.

Answer 66

tube clearance

Question 67

In tube bundles inside shell-and-tube heat exchangers, the shortest center-to-center distance between adjacent tubes is called the ___.

Answer 67

tube pitch.

Question 68

Which of the following is true as regard square pitch in tube bundles in shell-and-tube heat exchangers?

Answer 68

It makes the tubes more available for external cleaning

Question 69

Which feeding strategy in multiple-effect evaporation is required if the final concentrated product is highly viscous?

Answer 69

backward feeding

Question 70

Improving the economy of an evaporator system by using multiple effect evaporator system results to

Answer 70

decreased capacity

Question 71

Which of the following evaporator types is not well suited to concentrate heat-sensitive materials?

Answer 71

Forced-circulation evaporator

Question 72

Which of the following is true as regard evaporation as a unit operation?

Answer 72

involves the principle of decreasing the solubility of solid

Question 73

Each Duhring line indicates that

Answer 73

the BPR of a solution is proportional to the concentration of the solution

Question 74

Which feeding strategy in multiple-effect evaporation is required if the final concentrated has a tendency to decompose at high temperature?

Answer 74

backward feeding

Question 75

Which feeding strategy in multiple-effect evaporation requires feed pump and product pump only and no pumps in between any two effects?

Answer 75

forward feeding

Question 76

Which of the following concepts, principles or terminologies is not related to crystallization analysis and design?

Answer 76

Duhring’s law

Question 77

If all crystals in magma grow in a uniform supersaturation field and at the same temperature and if all crystals grow from birth at the rate governed by the supersaturation then, according to ΔL Law, which of the following are true: (1) All crystals are of the same type; (2) All crystals have the same growth rate; (3) Crystals grow at a rate which is proportional to size?

Answer 77

1 and 2

Question 78

Which of the following methods of accomplishes reaching supersaturation by addition of a non-solvent, which decreases the solubility of the solute?

Answer 78

drowning

Question 79

Which of the following is not assumed by the MSMPR model?

Answer 79

Efficient classification of crystal sizes in the withdrawal system