HeatX

Question 1

What flow path within a heat exchanger will reach an equilibrium in temperature half way between the two extremes

Answer 1

Parallel flow

Question 2

What flow path within a heat exchanger will reach the cooler of the two temperature extremes given enough time

Answer 2

Counter flow

Question 3

What flow path has the greatest efficiency for a given size

Answer 3

Counter flow

Question 4

What is the primary purpose of the fins on a finned tube exchanger

Answer 4

To increase surface areas

Question 5

Which of the heat exchangers has very efficient true counter flow

Answer 5

Spiral because of its continuous curving passages it creates high turbulence.

In turn the velocity of the fluid scrubs it clean. This exchanger is an excellent choice for fluids that tend to deposit sludge

Question 6

Within cooling towers the heat exchange is dependent on

Answer 6

Evaporation

Question 7

What is the purpose of the zink anodes in a shell and tube heat exchanger

Answer 7

To minimize electrolytic action within the heat exchanger

Question 8

What heat exchanger has its capacity changed the easiest.

Answer 8

Plate

Question 9

Cooling towers are commonly used to do what

Answer 9

Recycle water, the water to be cooled is pumped to the top of the tower where it is sprayed through a Nozel to give a fine spray, some evaporates cooling the remainder

Question 10

What baffle is used to reduce erosion by entering fluids

Answer 10

Impigmant

Question 11

What are the two common functions of shell side baffles

Answer 11

To increase turbulent flow and support the tube bundle

Question 12

How many longitudinal shell baffles are required to get four passes

Answer 12

3

Question 13

Which heat exchanger is limited to chemical cleaning of the tube side

Answer 13

U-tube

Question 14

What heat exchanger is most likely to suffer from thermal stress causing tube sheet leakage

Answer 14

Fixed tube sheet

Question 15

What’s the main advantage and disadvantage of the floating head exchanger

Answer 15

The advantage is it’s easier to clean

The disadvantage is the large clearance requirements needed

Question 15

What is a disadvantage to the floating head outside-packed, lantern ring exchanger

Answer 15

If the exchanger leaks the fluids are exposed to the atmosphere

Question 16

Where is a double tube sheet exchanger used

Answer 16

In applications where is is not desirable to have mixing of tube-side and shell-side fluids

It is impossible for this set up to have any mixing and will drip externally

Question 17

What fluid usually flows through the tube side

Answer 17

The dirtier fluid as it’s easier to clean through the tubes

Question 18

Higher pressure fluid flows through tubes of shell side?

Answer 18

Tube side as it could possible collapse the tubes if it flowed through shell side

Question 19

The fluid with the lower heat transfer usually travels where?

Answer 19

The outside of the tubes, it’s cheaper and easier to add fins for heat transfer

Question 20

What is TEMA

Answer 20

Tubular Exchanger Manufacturers Assosiation

Question 21

What is the advantage of a floating head with split backing device

Answer 21

Allows for more tubes to fit in the shell while allowing for thermal growth

Question 22

Heat transfer is primarily effected by what 5 causes

Answer 22

Fluid flow
Temperature differentials 
Hearing surface area
Contact time
Conductivity

Other factors would consist of Fluid films
Thickness of heating surface
Cleanliness of hearing surface

Question 23

What is a surface layer

Answer 23

A film or a fluid stuck to the metal wall

Question 24

Cold start up is when....

Answer 24

You gradually start both fluids at the same time

Question 25

Shutdown is when you....

Answer 25

Gradually stop both fluids at the same time

Question 26

What are the three most common causes to Poor performance in heat exchangers

Answer 26

Leaking tube sheets Fouling Vibration

Question 27

An increase in resistance to fluid flow and heat transfer due to undesired deposits is referred to as

Answer 27

Fouling Deposit build up lowers heat transfer rate

Question 28

What should you never use to clean a heat exchanger

Answer 28

Steam

Question 29

It's ok to screw eye bold I to the tube sheets

Answer 29

Yes, tubes are thin and bend easy so rigging on each end is most desirable

Question 30

Stress cracks in tubes are a sign of what

Answer 30

High stresses caused by continuous vibrations

Question 31

What is the purpose of hydrostatic testing

Answer 31

Used to check heat exchangers for leaks before and after overhauling - the standard for hydrostatic testing is 1-1/2 times the working pressure

Question 32

What precaution should be taken when loosening head studs.

Answer 32

Ensure exchanger has been purged vented and drained Loosen bolts at the bottom first

Question 33

What happends if you check leaks with hot water

Answer 33

Expansion could seal the leak

Question 34

What pressure is normally used for hydrostatic pressure

Answer 34

1-1/2 times the working pressure

Question 35

How is the shell side of an exchanger cleaned.

Answer 35

Hot water or chemical

Question 36

What is the advantage of a pull through floating head exchanger

Answer 36

Larger clearance around tube bundle = less surface area

Question 37

How could you tell if there was a tube sheet leak on a double tube sheet exchanger

Answer 37

Drips between the two tube sheets

Question 38

She'll and tube exchanger sizes are classified by

Answer 38

Shell Dia. and tube length

Question 39

Define the purpose of a heat exchanger.

Answer 39

To cool or heat liquid through a variety of processes

Question 40

Define conduction

Answer 40

The transfer of heat energy from one molecule to another or contact of fluid and a metal

Question 41

Define Convection

Answer 41

The result of the movement of mass of fluid (gas or liquid)from a warm location to a cooler one

Question 42

Define radiation

Answer 42

The transfer of energy by electro magnetic wave

Question 43

Different materials have different rates of thermal expansion What potential problems in a heat exchanger are related to this.

Answer 43

Loosening of joints

Question 44

Different materials have different rates of thermal expansion Name two exchanger designs that illuminate this problem

Answer 44

Utube Floating head

Question 45

Three advantages of uTube exchanger

Answer 45

Both ends are fixed illuminating thermal expansion problems Easy to remove and clean Well suited for high-temp/high pressure

Question 46

What's the most common way a tube is attached to a tube sheet

Answer 46

Expansion into tube sheet Rolled in And welding are the other two types

Question 47

The rate of heat transfer is effected by

Answer 47

Temperature difference Area of contact Conductivity of metal Nature of substance

Question 48

What flow is most desirable in a heat exchanger

Answer 48

Turbulent flow Scrubs the walls allowing more heat transfer

Question 49

Mixed flow is common where

Answer 49

In heat exchangers with baffles that cause the flows to Switch between parallel and counter flow

Question 50

What flow PATH is more desirable

Answer 50

Counter flow is more efficient

Question 51

What type of exchanger is a common radiator

Answer 51

Finned tube Greater surface area

Question 52

Why are spiral heat exchangers so efficient

Answer 52

Both fluids have true contour Dead bypasses are illuminated Less fouling

Question 53

Why is part of the water evaporated in the cooling tower

Answer 53

The heat to evaporate is drawn from the remaining water Resulting in a temp drop in the reaming water

Question 54

What type of cooling tower has a fan that forces the water out

Answer 54

Induced draft

Question 55

The heat exchanger that has a pipe concentric inside another pipe is called

Answer 55

Double pipe Perfect for high pressure Designed for counter flow current

Question 56

What baffles are normally provided over the tubes to reduce erosion by the entering fluid

Answer 56

Impigman baffles

Question 57

What baffle is used to split the shell side flow

Answer 57

Longitudinal

Question 58

Mixed flow is common where

Answer 58

In heat exchangers with baffles that cause the flows to Switch between parallel and counter flow

Question 59

What flow PATH is more desirable

Answer 59

Counter flow is more efficient

Question 60

What type of exchanger is a common radiator

Answer 60

Finned tube Greater surface area

Question 61

Why are spiral heat exchangers so efficient

Answer 61

Both fluids have true contour Dead bypasses are illuminated Less fouling

Question 62

Why is part of the water evaporated in the cooling tower

Answer 62

The heat to evaporate is drawn from the remaining water Resulting in a temp drop in the reaming water

Question 63

What type of cooling tower has a fan that forces the water out

Answer 63

Induced draft

Question 64

The heat exchanger that has a pipe concentric inside another pipe is called

Answer 64

Double pipe Perfect for high pressure Designed for counter flow current

Question 65

What baffles are normally provided over the tubes to reduce erosion by the entering fluid

Answer 65

Impigman baffles

Question 66

What baffle is used to split the shell side flow

Answer 66

Longitudinal

Question 67

What is the main disadvantage of the floating head exchanger compared to the floating head with the baking device

Answer 67

The disadvantage of the pull through exchanger is the the large clearance requirements between outer tubes and shell