Powerpoint: Receivers/Evaporators Flashcards

1
Q

Filling receivers with liquid is ______

A

illegal

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2
Q

A receiver is essentially a _______ tank for refrigerant

A

storage

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3
Q

The receiver is a _____ side component

A

high

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4
Q

The Receiver inlet is from the _________ and the outlet goes to the ______________

A

condenser, metering device

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5
Q

Refrigerant receiver types;

Full size receiver: holds _______ system charge

A

holds entire system charge

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6
Q

Refrigerant receiver types;

Oversized receiver: holds ______ system charge (condenser flooding)

A

excess

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7
Q

Refrigerant receiver types;

Partial receiver: holds a ______ of the system charge and the rest in condenser (not in canada)

A

portion

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8
Q

What are the inlet and outlet valves called in a full size receiver?

A

Inlet - Queen valve

Outlet valve quill- King valve

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9
Q

Inlet and Outlet valves in a partial receiver?

A

Inlet - no valve

Outlet valve quill - King

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10
Q

Receiver capacity as required by B-52:

  1. Must hold the entire refrigerant charge and only occupy ___% of its volume at ___F
  2. If refrigerant side head pressure capacity control is used the receiver must be oversized by ___%
A
  1. 90%, 90F

2. 50%

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11
Q

A cooling tower is a device for cooling water on a __________ system

A

recirculating

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12
Q

Cooling towers have no ________

A

refrigerant

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13
Q

Cooling towers use water to ______ heat from the water

A

reject

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14
Q

In a cooling tower, water is pushed to the ____ of the tower from the water cooled condenser and heat is rejected and _______ out the top

A

top

rejected and removed out of the top

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15
Q

Cooling tower low ambient controls;

  1. _______ valve
  2. diverting _____
  3. fan ______ ______
A
  1. mixing valve
  2. diverting valve
  3. fan speed control
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16
Q

Evaporators _______ heat into the refrigeration system

A

absorb

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17
Q

Evaporators absorb heat by maintaining the evaporator at a temperature ______ than the medium to be cooled

18
Q

Evaporators remove both ______ heat and _______ heat from the medium to be cooled

A

latent heat and sensible heat

19
Q

Evaporator types:

  1. Dry (DX): Liquid/Vapour mix to start and a ____ at the exit
  2. Flooded:
    - _____ level of liq ref (used on direct or indirect systems)
    - Ref charge of flooded evap is _____than a DX evap
    - Used for ______ systems (ie. ice rinks)
A
  1. gas

2. Constant, larger, larger

20
Q

Construction of Evap:

  1. Bare pipe
  2. Finned Tube: fins increase surface area and attach to pipe to increase __________
  3. Plate: (may use eutectic solution) semi trucks and______ low freezers
  4. Shell and tube: flooded or dry indirect systems seen in chillers
A
  1. heat exchange

3. ultra low

21
Q

Finned tube type: ____ velocity

temperature range is ___F and above

22
Q

Unit cooler temperature range is ____F and above (most common)

A

-40F and above

23
Q

Product cooler temp range is ____F and above and is the largest evaporator

A

-40F and above

24
Q
  • Fin spacing and temperature application:
    1. Frosting application- product coil must be below ___F (approx __fin/inch)
      1. Defrost method must have an external heat source to raise temp above ____F
      2. When in defrost you must shut off the evap ____
      3. External heat sources could be hot ____, ______, or hot _____
A
  1. 32F, 4fin/inch
  2. 32F
  3. fan
  4. hot gas, electric, hot water
25
* Fin spacing and temperature application: * 1. Defrosting application- coil must be below ___F and product above ___F (approx __fin/inch) 2. Defrost method is ___/_______ 3. keep the evaporator fan ________ during defrost
1. 32F, 32F, 6fin/inch 2. air / positive 3. running
26
* Fin spacing and temperature application: * 1. Non-frosting application -coil above ___F (approx __fin/inch) 2. The defrost method is ____ required 3. Improved fin designs reduces stratification by causing _______
1. 32F, 8fins/inch 2. not required 3. turbulence
27
DEFROSTING METHODS; 1. Electric (most common): lower first cost higher operating cost, ____ and _____ released into the space 2. Hot gas (most efficient): ____ defrost with minimal _____ temperature rise Hot water (not common): ____F water is sprayed onto a coil at 3GPM, has ____ defrost but requires more maintenance
1. heat and moisture 2. fast, minimal space temperature rise 3. 50F, fast defrost
28
What are the three methods of stopping the defrost cycle known as defrost termination?
1. Time 2. Temperature 3. Pressure
29
Defrost Termination: Defrost timers with a solenoid can terminate defrost by ____ and _______
time and temperature
30
Defrost Termination Defrost timers with a solenoid are for ___ temp
low
31
Defrost Termination: Defrost timers without a solenoid are for ____ temperature
medium
32
Defrost Termination: Defrost timers without a solenoid can only terminate defrost by ____
time
33
Coil temperature difference (TD): this determines ______ humidity level
space
34
Coil Temperature difference: Evaporator coil TD= Air entering Evap - ____
SST
35
Normal coil TD’s and Relative Humidity: - 8 to 10F = - 10 to 12F = - 12 to 14F = - 14 to 18F =
8 to 10 = 90% + 10 to 12 = 85% to 90% 12 to 14F = 80 to 85% 14 to 18F = 70 to 80%
36
Purpose of refrigerant distributor: 1. Has multiple _____/ multi- circuit ____ 2. Eliminates ______ drop thru long coils by feeding ref. thru multiple circuits within the coil 3. provides equal _______ of liquid and vapour to each coil circuit
1. branches/multi circuit coils 2. pressure drop 3. distribution
37
Capacity control for evaporators: 1. Coil splitting methods; _____/row split (stacked), _____/face split (in line)
1. vertical, horizontal
38
Shell and tube evaporator types; | 2
Dry (DX) and Flooded
39
Shell and Tube Evaporators: 1. Dry- location of primary ref is on the ____ side and secondary ref on the ____ side 2. Purpose of baffled (full or half) is to provide maximum exposure of secondary ________ to primary refrigerant circuits
1. Tube, Shell | 2. refrigerant
40
Shell and Tube Evaporators: 1. Flooded- location of primary refrigerant ____ side and secondary ref on ____ side 2. Tube bundle on ______ of shell 3. Purpose of ________ is to prevent liquid ref from returning to the compressor 4. Surge drum (accumulator) provides for removal of _____ gas so it does not waste space in the cooler
1. shell side, tube side 2. bottom 3. eliminators 4. flash gas
41
Evaporator Capacity or Efficiency control: 1. _____ water flow at all times 2. Temperatures: low temp __F TD (secondary refrigerant entering/leaving) 3. High temp application ___ to ___F TD (secondary refrigerant entering/leaving) 4. Air Cond. chilled water supply at ___ to ___F 5. Air conditioning supply air temp ____F 6. Secondary ref controlled by ______ conditions
1. constant 2. 2F 3. 10 to 15F 4. 40 to 45F 5. 55F 6. entering