Powerpoint: Receivers/Evaporators

Question 1

Filling receivers with liquid is ______

Answer 1

illegal

Question 2

A receiver is essentially a _______ tank for refrigerant

Answer 2

storage

Question 3

The receiver is a _____ side component

Answer 3

high

Question 4

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

Answer 4

condenser, metering device

Question 5

Refrigerant receiver types;

Full size receiver: holds _______ system charge

Answer 5

holds entire system charge

Question 6

Refrigerant receiver types;

Oversized receiver: holds ______ system charge (condenser flooding)

Answer 6

excess

Question 7

Refrigerant receiver types;

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

Answer 7

portion

Question 8

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

Answer 8

Inlet - Queen valve

Outlet valve quill- King valve

Question 9

Inlet and Outlet valves in a partial receiver?

Answer 9

Inlet - no valve

Outlet valve quill - King

Question 10

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 ___%

Answer 10

1. 90%, 90F

2. 50%

Question 11

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

Answer 11

recirculating

Question 12

Cooling towers have no ________

Answer 12

refrigerant

Question 13

Cooling towers use water to ______ heat from the water

Answer 13

reject

Question 14

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

Answer 14

top

rejected and removed out of the top

Question 15

Cooling tower low ambient controls;

1. _______ valve
2. diverting _____
3. fan ______ ______

Answer 15

1. mixing valve
2. diverting valve
3. fan speed control

Question 16

Evaporators _______ heat into the refrigeration system

Answer 16

absorb

Question 17

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

Answer 17

lower

Question 18

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

Answer 18

latent heat and sensible heat

Question 19

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)

Answer 19

1. gas

2. Constant, larger, larger

Question 20

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

Answer 20

2. heat exchange

3. ultra low

Question 21

Finned tube type: ____ velocity

temperature range is ___F and above

Answer 21

28

Question 22

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

Answer 22

-40F and above

Question 23

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

Answer 23

-40F and above

Question 24

• Fin spacing and temperature application:
• 1. Frosting application- product coil must be below ___F (approx __fin/inch)
     
     2. Defrost method must have an external heat source to raise temp above ____F
     3. When in defrost you must shut off the evap ____
     4. External heat sources could be hot ____, ______, or hot _____

Answer 24

1. 32F, 4fin/inch
2. 32F
3. fan
4. hot gas, electric, hot water

Question 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

Answer 25

1. 32F, 32F, 6fin/inch
2. air / positive
3. running

Question 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 _______

Answer 26

1. 32F, 8fins/inch
2. not required
3. turbulence

Question 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

Answer 27

1. heat and moisture
2. fast, minimal space temperature rise
3. 50F, fast defrost

Question 28

What are the three methods of stopping the defrost cycle known as defrost termination?

Answer 28

1. Time
2. Temperature
3. Pressure

Question 29

Defrost Termination:

Defrost timers with a solenoid can terminate defrost by ____ and _______

Answer 29

time and temperature

Question 30

Defrost Termination

Defrost timers with a solenoid are for ___ temp

Answer 30

low

Question 31

Defrost Termination:

Defrost timers without a solenoid are for ____ temperature

Answer 31

medium

Question 32

Defrost Termination:

Defrost timers without a solenoid can only terminate defrost by ____

Answer 32

time

Question 33

Coil temperature difference (TD):

this determines ______ humidity level

Answer 33

space

Question 34

Coil Temperature difference:

Evaporator coil TD= Air entering Evap - ____

Answer 34

SST

Question 35

Normal coil TD’s and Relative Humidity:

• 8 to 10F =
• 10 to 12F =
• 12 to 14F =
• 14 to 18F =

Answer 35

8 to 10 = 90% +

10 to 12 = 85% to 90%

12 to 14F = 80 to 85%

14 to 18F = 70 to 80%

Question 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

Answer 36

1. branches/multi circuit coils
2. pressure drop
3. distribution

Question 37

Capacity control for evaporators:

1. Coil splitting methods; _____/row split (stacked), _____/face split (in line)

Answer 37

1. vertical, horizontal

Question 38

Shell and tube evaporator types;

2

Answer 38

Dry (DX) and Flooded

Question 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

Answer 39

1. Tube, Shell

2. refrigerant

Question 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

Answer 40

1. shell side, tube side
2. bottom
3. eliminators
4. flash gas

Question 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

Answer 41

1. constant
2. 2F
3. 10 to 15F
4. 40 to 45F
5. 55F
6. entering