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Evap, Cond, MD, Receivers > Powerpoint: Condensers > Flashcards

Powerpoint: Condensers Flashcards

1
Q

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

A

reject

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2
Q

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

A

vapour to a liquid

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3
Q

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

A

evaporator

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4
Q

Name 3 condensing mediums;

A

Air
Water
Evaporative (mixture of air and water)

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5
Q

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

A

evaporator, suction line, and compressor

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6
Q

_____ for open drive compressor capacity

A

1.25 x

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7
Q

______ for hermetic/semi hermetic compressors capacity

A

1.3

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8
Q

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

A

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

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9
Q

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

A

15 degrees fahrenheit

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10
Q

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

A

25 to 35F

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11
Q

Ambient temperature makes a huge difference in ___ ________ condensers

A

air cooled condensers

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12
Q

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

A

10F

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13
Q

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

A

0.5%

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14
Q

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

A

saturation

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15
Q

Name the two air condenser types.

A

Natural convection

Forced air

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16
Q

Name two forced air fans

A 
propeller fan (draw through)
centrifugal fan (push through)
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17
Q

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

A

75 to 100psig

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18
Q

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

A

55

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19
Q

Name three air side capacity controls?

A

Fan speed, modulating dampers, fan cycling

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20
Q

Ref side capacity control characteristics:

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

A

flood

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21
Q

Refrigerant side of capacity control:

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

A

heater

22
Q

O.R.I valve?

A

Opens on a rise of inlet

measures condenser outlet pressure

23
Q

O.R.D valve?

A

Opens on rise of differential

24
Q

O.R.O.A valve?

A

Opens on a rise of outlet pressure automatically

25
Q

Name three advantages of an air cooled condenser?

A

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

26
Q

Name three disadvantages of an air cooled condenser?

A
  • 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
27
Q

Name two methods of water cooled condensers?

A

Recirculating or waste water systems

28
Q

Name the three types of water cooled condensers;

A

tube in tube, shell and coil, shell and tube

29
Q

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

A

85 and 110F

30
Q

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

A

outlet

31
Q

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

A

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

32
Q

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

A

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

33
Q

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

A

105F

34
Q

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

A

head, spring

35
Q

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

A

higher

36
Q

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

A

lower

37
Q

Name 3 advantages of water cooled condensers;

A
  • Smaller size
  • Constant SDT
  • No requirement for capacity control during periods of low outside temp
38
Q

Name three disadvantages of water cooled condensers?

A
  • Not suitable for outdoor use
  • water may be expensive
  • bylaws may require an expensive recirculating system (cooling tower)
39
Q

Evaporative Condensers use _____ and ____ as the condensing medium

A

water and air

40
Q

Evaporative condensers are used on ______ capacity systems

A

larger

41
Q

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

A

wet

42
Q

Wet bulb is based on ____ temp and ______ humidity

A

Air temp and relative humidity

43
Q

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

A

remaining

44
Q

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 ____

A

drain

45
Q

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

A

blow down

46
Q

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

A

heated, heated

47
Q

Condenser heat rejection factors:

  1. Surface Area of fins; __ to ___ fin/inch
A

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

48
Q

Condenser heat rejection factors:

  1. Type of Material used (thermal _______)
A

thermal

conductivity

49
Q

Condenser heat rejection factors:

  1. ________ of surface
A

cleanliness of surface

50
Q

Condenser heat rejection factors:

  1. Condensing medium temperature difference;
    Air is ___ to ____F and 600 to 1200CFM @1000FPM
A

15 to 35F

51
Q

Condenser heat rejection factors:

  1. 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

A
  • 1.5

- 3

52
Q

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

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