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Air Conditioning > Basic Refrigeration > Flashcards

Basic Refrigeration Flashcards

1
Q

What does CFC stand for?

A

Chlorofluorocarbon

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2
Q

List the 3 basic types of condensers?

A

Air-cooled, water-cooled, and evaporation

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3
Q

Define temperature?

A

The measure of the intensity of heat of a substance and the measure of it’s molecular speed expressed in degrees.

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4
Q

What is a sub-cooled liquid?

A

A liquid that has been cooled below the boiling temperature, at a specific temperature.

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5
Q

What is a superheated vapour?

A

A vapour heated to a temperature above its saturation point.

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6
Q

One ton of cooling is equivalent to?

A

12 000 Btu/hr

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7
Q

A recovery cylinder should be filled to a maximum of ___ it’s capacity?

A

80 percent

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8
Q

What type of PPE must be worn to prevent injury from frostbite?

A

Eye protection, gloves, and proper clothing.

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9
Q

Is it necessary to obtain a permit before installing a cooling system?

A

Yes, you need one for every installation

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10
Q

What are the 3 types of metering devices?

A

Thermostatic expansion valve, capillary tube, and orifice

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11
Q

When the refrigerant leaves the condenser it is a?

A

Hot high pressure liquid

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12
Q

One type of filter drier can be used for all types of refrigerant. True or False?

A

False

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13
Q

What are the components of a basic cooling system?

A

Compressor, evaporator, condenser, metering device, piping, and filter drier

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14
Q

Which side of the system is the evaporator considered to be in?

A

The low pressure side

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15
Q

How many pressure changes will the refrigerant in a cooling system undergo in a complete cycle?

A

Two

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16
Q

What are 3 types of dehumidifiers?

A

Heat pump, chemical absorbent, and ventilating humidifier

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17
Q

The heat pump dehumidifier works under the same basic principles as an air conditioning heat pump. True or False?

A

True

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18
Q

Why do dehumidifying ventilators not work well in hot humid climates?

A

Because they bring in more outside air into the house which has more moisture in it.

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19
Q

5 tons of cooling is equal to?

A

60,000 BTU

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20
Q

Cooling systems are ___ systems and must function under pressure to work properly.

A

Closed (sealed)

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21
Q

In simplest terms, what does a cooling system do?

A

It must take heat from where it is not wanted and relocate it to where it does not matter.

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22
Q

Refrigerant is changed from a ___ to a ___ as it travels through the system

A

Vapour to a liquid

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23
Q

Refrigeration systems operate on what kind of cycle?

A

Closed cycle

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24
Q

What are the two most frequently used closed refrigeration systems?

A

The compression system (vapour-compression or mechanical) and the absorption system (non-mechanical)

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25
Q

The basic compression refrigeration cycle is divided into what 2 sides?

A

A high pressure side and a low pressure side

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26
Q

What can compressors only pump out?

A

Vapours only

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27
Q

In compression refrigeration systems the refrigerant is subjected to what four different processes?

A

Heat gain from a liquid to a gas, pressure and temperature rise, heat loss from gas into a liquid, and pressure loss in the liquid metering device which changes temperature and state of the refrigerant.

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28
Q

The refrigeration cycle involves?

A

Two pressure changes and two heat transfer changes

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29
Q

What is sub cooling?

A

A liquid that has been cooled below the boiling temperature at a specific pressure.

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30
Q

Define superheat?

A

A vapour heated above its saturation point.

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31
Q

What does the compressor do?

A

Keeps the refrigerant flowing at specific pressures and flow rates. Pumps the refrigerant throughout the system.

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32
Q

What is referred to as the heart of the system?

A

The compressor

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33
Q

What does the evaporator do?

A

It is the component that absorbs the heat from the medium to be cooled.

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34
Q

What are the three basic types of condensers?

A

Air-cooled, water-cooled, and evaporative

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35
Q

What does the condenser do?

A

It’s the component that removes heat from the system.

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36
Q

What are the three basic types of water-cooled condensers?

A

Double-tube, shell and coil, and shell and tube

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37
Q

How are double tube condensers constructed?

A

With one or more water tubes contained concentrically within a larger tube.

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38
Q

How much heat is absorbed in the evaporation process?

A

970 Btu/lb

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39
Q

What is one of the most frequently used liquid metering devices in refrigeration?

A

The thermostatic expansion valve (TXV)

40
Q

Define orifice?

A

They allow the system to equalize pressure when the compressor is off. They are supplied with air conditioning equipment in place of capillary tubes.

41
Q

Define capillary tube?

A

Provides a very simple means of reducing the pressure from the high pressure side of the refrigeration system to the low pressure side.

42
Q

ACR copper tubing is available in which two types?

A

Type K(Thick wall) and Type L(Thin wall)

43
Q

Types K and L are available in what two tempers?

A

Drawn temper and annealed temper

44
Q

What type of pipe is used in air conditioning and refrigeration?

A

ACR tubing

45
Q

What is the purpose of a filter drier?

A

To remove contaminates that may be present in the refrigerant stream and to remove moisture that may have been introduced into the system during install or charging.

46
Q

In the refrigeration system the refrigerant ____ while changing from a liquid to a gas and ____ in changing from a gas to a liquid.

A

absorbs heat, releases heat

47
Q

Define critical temperature?

A

The highest temperature at which a gas may be liquefied.

48
Q

Define saturation temperature?

A

A condition of both pressure and temperature at which both liquid and vapour can exist in the same container simultaneously.

49
Q

That is critical pressure of a liquid?

A

A liquid will remain a liquid no matter how much heat is applied to it.

50
Q

Define thermodynamics?

A

The branch of science dealing with the mechanical action of heat.

51
Q

Heat always travels from a ____ object to a ____ object.

A

Warm to cold

52
Q

What are three methods of heat transfer involved in refrigeration?

A

Conduction, radiation, and convection

53
Q

What is the greatest method of heat transfer?

A

Conduction

54
Q

What is the lowest method of heat transfer?

A

Radiation

55
Q

The part of the evaporator in which liquid is vaporizing is called?

A

Active

56
Q

Licensed journeyman sheet metal workers and apprentices in Alberta are allowed to install and service split systems up to?

A

5 tons or 60,000 Btuh

57
Q

A ton of refrigeration is the refrigeration produced by melting?

A

One ton (2000 pounds) of ice at 32 degrees F ( 0 degrees C) in 24 hours.

58
Q

Describe dehydration (evacuation)?

A

A common method of evacuation using a vacuum pump to lower the pressure inside the refrigeration system so that air and moisture can be drawn out of the system.

59
Q

What are the physical laws governing cooling?

A

A liquid cannot become a gas unless it absorbs heat, a gas cannot become a liquid unless it gives off heat, and a liquid will not convert to a gas as readily under pressure.

60
Q

What is a refrigerant?

A

A substance used for heat transfer.

61
Q

What is entropy?

A

How quickly the heat is released

62
Q

It is law that?

A

No refrigerants are released into the atmosphere.

63
Q

Over 50 percent pf air condition systems use?

A

R-22

64
Q

When a refrigerant escapes or is released into the atmosphere, its temperature drops ____?

A

Instantly

65
Q

What does a dehumidifier do?

A

Removes moisture from the air without cooling the air.

66
Q

The average temperature for AC is?

A

55 degrees f

67
Q

What does the condenser do?

A

Rejects (gives off) heat from the system

68
Q

What does the evaporator do?

A

Absorbs heat into the system.

69
Q

Which is better? Thermostatic expansion valve TXV or a fixed orifice.

A

TXV is better and becoming more standard.

70
Q

What is the thermostatic expansion valve used for?

A

To meter the flow of liquid refrigerant to the evaporator coil.

71
Q

Type K and L tuping are available with which type of tempers?

A

Drawn temper (hard pipe) and annealed temper (flexible pipe)

72
Q

What is sensible heat?

A

The heat required to produce a change in temperature of a substance but not a change of state.

73
Q

Describe conduction?

A

Occurs when two object at different temperatures are in contact with each other.

74
Q

Describe radiation?

A

The emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionization.

75
Q

Describe convection?

A

The transfer of heat by the movement of a fluid (liquid or gas) between areas of different temperature.

76
Q

The higher the seer rating the more quiet the condenser is. True or False?

A

True

77
Q

1 kw = ?

A

3410 BTU’s

78
Q

1 ton of cooling = ?

A

36 000 BTU’s (400 CFM per ton)

79
Q

If you have refrigerant you ___ off the system.

A

Cool off

80
Q

Nitrogen is good for line and moisture is bad for lines. True or False?

A

True

81
Q

When using A/C how high do you want to set the fan?

A

As high as possible

82
Q

You should avoid putting condensers in the sun. The coolest spot is the best. True or False?

A

True

83
Q

What is latent heat?

A

A change in state but not a change of temperature

84
Q

How many BTUs are required to change the state of water from a solid to a liquid?

A

144 Btu’s

85
Q

At no time shall liquid be aloud to enter the compressor. True or False?

A

True

86
Q

What is flash gas?

A

When the pressure is reduced on the liquid a small portion of the liquid boils off due to the pressure drop.

87
Q

As pressure increases, does the boiling point increase or decrease?

A

Increase

88
Q

Which type of refrigerant is the worst for the ozone?

A

CFC

89
Q

Which metering device auto regulates the amount of refrigerant into the system?

A

The thermostatic expansion valve

90
Q

Describe recover?

A

It is the removal of refrigerants into an approved container.

91
Q

What is the latent heat of fusion (solid to a liquid)?

A

144 Btu’s

92
Q

If a capillary tube evaporator coil is purchased, can it’s size be increased or decreased?

A

No

93
Q

What is important about the type of copper used in refrigeration?

A

It needs to be charged with nitrogen, cleaned, and dried

94
Q

What is the location of the TXV valve?

A

Liquid line near evaporator coil

95
Q

What is the location of the temperature sensing bulb of the TXV valve?

A

Refrigeration flow coil out of the evaporator

96
Q

What is the location of the fixed orifice?

A

Refrigeration flow coil out of the evaporator

97
Q

Where is the location of the capillary tube?

A

Refrigeration flow coil out of the evaporator

Air Conditioning (2 decks)

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