Powerpoint: Condensers

Question 1

A condensers function is to _______ heat from the refrigerant to the condensing medium

Answer 1

reject

Question 2

Condensers cause the refrigerant to change state from a _______ to a _______

Answer 2

vapour to a liquid

Question 3

The condenser must reject the heat absorbed in the _________ suction line and the compressor

Answer 3

evaporator

Question 4

Name 3 condensing mediums;

Answer 4

Air
Water
Evaporative (mixture of air and water)

Question 5

The condenser heat rejection is larger than evap/comp as it must reject heat from the ___________ , ______ line, and __________

Answer 5

evaporator, suction line, and compressor

Question 6

_____ for open drive compressor capacity

Answer 6

1.25 x

Question 7

______ for hermetic/semi hermetic compressors capacity

Answer 7

1.3

Question 8

Fine size of condenser required for a ref. system with a hermetic compressor having a capacity of 24,000btu/hr?

Answer 8

24,000 x 1.3 = 31,200 btu/hr

Question 9

Normal temp difference of ambient air to saturated discharge temp in a high efficiency compressor is?

Answer 9

15 degrees fahrenheit

Question 10

Normal temp difference of ambient air to saturated discharge temp in a normal condenser is ____F to _____F

Answer 10

25 to 35F

Question 11

Ambient temperature makes a huge difference in ___ ________ condensers

Answer 11

air cooled condensers

Question 12

A ___F change in ambient temperature will change condenser capacity by 3%

Answer 12

10F

Question 13

A 1F change in condenser sub cooling will change system capacity by ___%

Answer 13

0.5%

Question 14

Sub cooling liquid temp MUST be colder than the ________ temp (temperature differential)

Answer 14

saturation

Question 15

Name the two air condenser types.

Answer 15

Natural convection

Forced air

Question 16

Name two forced air fans

Answer 16

propeller fan (draw through)
centrifugal fan (push through)

Question 17

Capacity control is required to maintain a proper pressure drop of ___ to ____ psig at the metering device

Answer 17

75 to 100psig

Question 18

Capacity control is usually required if the outdoor ambient temperature falls below ___F

Answer 18

55

Question 19

Name three air side capacity controls?

Answer 19

Fan speed, modulating dampers, fan cycling

Question 20

Ref side capacity control characteristics:

The receiver is sized larger to accommodate refrigerant charge required to _____ the condenser

Answer 20

flood

Question 21

Refrigerant side of capacity control:

The receiver may be equipped with a _____ (usually on small condensers)

Answer 21

heater

Question 22

O.R.I valve?

Answer 22

Opens on a rise of inlet

measures condenser outlet pressure

Question 23

O.R.D valve?

Answer 23

Opens on rise of differential

Question 24

O.R.O.A valve?

Answer 24

Opens on a rise of outlet pressure automatically

Question 25

Name three advantages of an air cooled condenser?

Answer 25

Air is readily available Lower initial cost at installation Simpler maintenance No freeze up issues

Question 26

Name three disadvantages of an air cooled condenser?

Answer 26

- Large volume of air may be needed - Noise may be a problem - Operating costs may be higher - Large variations in discharge pressure due to ambient temperature swing

Question 27

Name two methods of water cooled condensers?

Answer 27

Recirculating or waste water systems

Question 28

Name the three types of water cooled condensers;

Answer 28

tube in tube, shell and coil, shell and tube

Question 29

In water cooled condensers, the saturated discharge temperature is controlled by a water regulating valve set at between ___F and ____F

Answer 29

85 and 110F

Question 30

The preferred location of the water regulating valve in a water cooled condenser is at the ______ condenser

Answer 30

outlet

Question 31

why is the water regulating valve preferred location at the outlet of the water cooled condenser?

Answer 31

To prevent air from entering and increasing the rate of oxidation inside the condenser

Question 32

How do you set the water regulating valve between 85 and 110 in a water cooled condenser?

Answer 32

Use the PT chart and find the pressure setting based on temperature and type of refrigerant and adjust valve based on these

Question 33

The IDEAL saturated discharge temp of ____F is the ideal head pressure in a water cooled condenser

Answer 33

105F

Question 34

In a water cooled condenser, the _____ pressure is the opening force of the water regulating valve and the ____ is the closing force

Answer 34

head, spring

Question 35

______ head pressure is higher compression of the spring (water cooled condenser)

Answer 35

higher

Question 36

______ head pressure is lower compression of spring (water cooled condenser)

Answer 36

lower

Question 37

Name 3 advantages of water cooled condensers;

Answer 37

- Smaller size - Constant SDT - No requirement for capacity control during periods of low outside temp

Question 38

Name three disadvantages of water cooled condensers?

Answer 38

- Not suitable for outdoor use - water may be expensive - bylaws may require an expensive recirculating system (cooling tower)

Question 39

Evaporative Condensers use _____ and ____ as the condensing medium

Answer 39

water and air

Question 40

Evaporative condensers are used on ______ capacity systems

Answer 40

larger

Question 41

Evaporative condensers capacity is based on the _____ bulb temperature of air entering

Answer 41

wet

Question 42

Wet bulb is based on ____ temp and ______ humidity

Answer 42

Air temp and relative humidity

Question 43

In Evaporative condensers, as water evaporates, solids are left behind and concentrate in the ________ water

Answer 43

remaining

Question 44

In Evaporative condensers, to prevent the dissolved liquids from over concentrating and forming deposits on the condenser tubes, a portion of the circulating water must be to ____

Answer 44

drain

Question 45

In evaporative condensers, periodically the water must be emptied to flush out mineral deposits, this is called ____ ____

Answer 45

blow down

Question 46

If Evaporative condensers are used in a cold climate the sump must be ______ or located in a _____ space

Answer 46

heated, heated

Question 47

Condenser heat rejection factors: 1. Surface Area of fins; __ to ___ fin/inch

Answer 47

8 to 16 fin/inch (more fins means more efficiency)

Question 48

Condenser heat rejection factors: 2. Type of Material used (thermal _______)

Answer 48

thermal | conductivity

Question 49

Condenser heat rejection factors: 3. ________ of surface

Answer 49

cleanliness of surface

Question 50

Condenser heat rejection factors: 4. Condensing medium temperature difference; Air is ___ to ____F and 600 to 1200CFM @1000FPM

Answer 50

15 to 35F

Question 51

Condenser heat rejection factors: 5. Water flow rates; - Waste water system (60F) flows at ____ gals/min/ton Recirculating water system has a closed cooling tower and flows at ____ gals/min/ton

Answer 51

- 1.5 | - 3

Question 52

Maintenance required for water cooled condensers; Name 6 1. Keep water passages _____ 2. Shell and could must be _______ cleaned 3. Check condenser for ______ 4. _____ water valve 5. Check water ____\____ temp 6. Clean condenser coils with a commercial cleaning agent solution such as _______

Answer 52

1. Clear 2. Chemically 3. leaks 4. flush 5. inlet/outlet 6. cal-clean