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Refrigeration Systems > Review > Flashcards

Review Flashcards

1
Q

What kind of metering devices are in refrigeration systems?

A

TXV
Automatic expansion valve
Capillary tubes

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2
Q

What are the three main functions of a TXV?

A
  • prevent floodback to the compressor
  • provide a constant amount of superheat
  • keep entire evaporator full of refrigerant
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3
Q

If there is contamination from a compressor burnout, the refrigerant may…

A

not be reused

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4
Q

If the orifice of capillary tubes are too small, it will ______ the evaporator.

A

starve

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5
Q

Why is it necessary to have superheat in a refrigeration system?

A

to ensure all the refrigerant is in a vapor state

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6
Q

What are the four stages of the refrigeration system?

A
  • compression
  • condensation
  • expansion
  • evaporation
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7
Q

The heat energy that causes a state change at a constant pressure is called…

A

latent heat

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8
Q

True or False:

Condensing pressure is the pressure at which refrigerant changes state from a vapor to a liquid.

A

True

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9
Q

True or False:

Evaporating pressure is the pressure at which refrigerant changes state from a liquid to a vapor.

A

True

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10
Q

What is the function of the compressor?

A

to circulate refrigerant

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11
Q

What is the function of the discharge line?

A

convey the refrigerant from the compressor to the condenser

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12
Q

In what types of systems do we see receivers and why?

A

In TXV systems to store refrigerant and act as a surge tank

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13
Q

What does the liquid line do in a refrigerant system?

A

carries high pressure liquid to the metering device

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14
Q

Where do the high side and low side of a refrigeration system divide?

A

Metering device

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15
Q

Superheat on a system is divided into what two parts?

A
  • evaporator superheat

- compressor superheat

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16
Q

Name four situations that can cause low evaporator loads.

A
  • iced up/dirty coil
  • evaporator fan motor not working
  • defrost circuit malfunction causes icing
  • end of refrigeration cycle
  • low air flow across evaporator coil
  • low refrigerant charge
17
Q

What is the difference between flooding and migration?

A

For migration the unit is off, flooding the unit is running.

18
Q

What are the reasons for slugging?

A
  • bad TXV
  • low load
  • dirty evaporator
  • overcharge
19
Q

What does the evaporator act as?

A

A heat exchanger

20
Q

True or False:

The suction line transports superheated vapor from the evaporator to the compressor.

A

True

21
Q

True or False:

If a capillary tube system is overcharged, it will back up excess liquid in the condenser.

A

True

22
Q

True or False:

If a capillary tube system is overcharged, it will cause high head pressure.

A

True

23
Q

Where do we install a filter/dryer in a capillary tube system and why?

A

Before the capillary tubes to catch foreign objects

24
Q

What is the color code for R-11, R-12, and R-134a?

A

R-11 is orange
R-12 is yellow
R-134a is blue

25
Q

What types of leak detectors do we have?

A
  • electronic leak detectors
  • UV fluorescent leak detectors
  • halide torch
  • refrigerant dyes
26
Q

Air can enter a refrigeration system in what three ways?

A
  • poor charging procedures
  • leaks
  • poor recovery
27
Q

Oil removed from a system can…

A

cause skin burns

28
Q

What does TEWI stand for?

A

total equivalent warming impact

29
Q

What does CAA stand for?

A

Clean Air Act

30
Q

How many classes is CAA divided into?

A

Two

31
Q

Section 608 of CAA prohibits individuals from doing what?

A

Knowingly venting of refrigerant into the atmosphere

32
Q

The EPA has established a certification for use when…

A

Working with refrigerants

33
Q

How many certifications did the EPA establish?

A

Four

34
Q

According to the EPA, equipment used for recovery and recycling of refrigerant must be equipped with…

A

Low loss fittings

Refrigeration Systems (1 decks)

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