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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
The basic compression refrigeration cycle is divided into what 2 sides?
A high pressure side and a low pressure side
26
What can compressors only pump out?
Vapours only
27
In compression refrigeration systems the refrigerant is subjected to what four different processes?
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.
28
The refrigeration cycle involves?
Two pressure changes and two heat transfer changes
29
What is sub cooling?
A liquid that has been cooled below the boiling temperature at a specific pressure.
30
Define superheat?
A vapour heated above its saturation point.
31
What does the compressor do?
Keeps the refrigerant flowing at specific pressures and flow rates. Pumps the refrigerant throughout the system.
32
What is referred to as the heart of the system?
The compressor
33
What does the evaporator do?
It is the component that absorbs the heat from the medium to be cooled.
34
What are the three basic types of condensers?
Air-cooled, water-cooled, and evaporative
35
What does the condenser do?
It's the component that removes heat from the system.
36
What are the three basic types of water-cooled condensers?
Double-tube, shell and coil, and shell and tube
37
How are double tube condensers constructed?
With one or more water tubes contained concentrically within a larger tube.
38
How much heat is absorbed in the evaporation process?
970 Btu/lb
39
What is one of the most frequently used liquid metering devices in refrigeration?
The thermostatic expansion valve (TXV)
40
Define orifice?
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
Define capillary tube?
Provides a very simple means of reducing the pressure from the high pressure side of the refrigeration system to the low pressure side.
42
ACR copper tubing is available in which two types?
Type K(Thick wall) and Type L(Thin wall)
43
Types K and L are available in what two tempers?
Drawn temper and annealed temper
44
What type of pipe is used in air conditioning and refrigeration?
ACR tubing
45
What is the purpose of a filter drier?
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
In the refrigeration system the refrigerant ____ while changing from a liquid to a gas and ____ in changing from a gas to a liquid.
absorbs heat, releases heat
47
Define critical temperature?
The highest temperature at which a gas may be liquefied.
48
Define saturation temperature?
A condition of both pressure and temperature at which both liquid and vapour can exist in the same container simultaneously.
49
That is critical pressure of a liquid?
A liquid will remain a liquid no matter how much heat is applied to it.
50
Define thermodynamics?
The branch of science dealing with the mechanical action of heat.
51
Heat always travels from a ____ object to a ____ object.
Warm to cold
52
What are three methods of heat transfer involved in refrigeration?
Conduction, radiation, and convection
53
What is the greatest method of heat transfer?
Conduction
54
What is the lowest method of heat transfer?
Radiation
55
The part of the evaporator in which liquid is vaporizing is called?
Active
56
Licensed journeyman sheet metal workers and apprentices in Alberta are allowed to install and service split systems up to?
5 tons or 60,000 Btuh
57
A ton of refrigeration is the refrigeration produced by melting?
One ton (2000 pounds) of ice at 32 degrees F ( 0 degrees C) in 24 hours.
58
Describe dehydration (evacuation)?
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
What are the physical laws governing cooling?
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
What is a refrigerant?
A substance used for heat transfer.
61
What is entropy?
How quickly the heat is released
62
It is law that?
No refrigerants are released into the atmosphere.
63
Over 50 percent pf air condition systems use?
R-22
64
When a refrigerant escapes or is released into the atmosphere, its temperature drops ____?
Instantly
65
What does a dehumidifier do?
Removes moisture from the air without cooling the air.
66
The average temperature for AC is?
55 degrees f
67
What does the condenser do?
Rejects (gives off) heat from the system
68
What does the evaporator do?
Absorbs heat into the system.
69
Which is better? Thermostatic expansion valve TXV or a fixed orifice.
TXV is better and becoming more standard.
70
What is the thermostatic expansion valve used for?
To meter the flow of liquid refrigerant to the evaporator coil.
71
Type K and L tuping are available with which type of tempers?
Drawn temper (hard pipe) and annealed temper (flexible pipe)
72
What is sensible heat?
The heat required to produce a change in temperature of a substance but not a change of state.
73
Describe conduction?
Occurs when two object at different temperatures are in contact with each other.
74
Describe radiation?
The emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionization.
75
Describe convection?
The transfer of heat by the movement of a fluid (liquid or gas) between areas of different temperature.
76
The higher the seer rating the more quiet the condenser is. True or False?
True
77
1 kw = ?
3410 BTU's
78
1 ton of cooling = ?
36 000 BTU's (400 CFM per ton)
79
If you have refrigerant you ___ off the system.
Cool off
80
Nitrogen is good for line and moisture is bad for lines. True or False?
True
81
When using A/C how high do you want to set the fan?
As high as possible
82
You should avoid putting condensers in the sun. The coolest spot is the best. True or False?
True
83
What is latent heat?
A change in state but not a change of temperature
84
How many BTUs are required to change the state of water from a solid to a liquid?
144 Btu's
85
At no time shall liquid be aloud to enter the compressor. True or False?
True
86
What is flash gas?
When the pressure is reduced on the liquid a small portion of the liquid boils off due to the pressure drop.
87
As pressure increases, does the boiling point increase or decrease?
Increase
88
Which type of refrigerant is the worst for the ozone?
CFC
89
Which metering device auto regulates the amount of refrigerant into the system?
The thermostatic expansion valve
90
Describe recover?
It is the removal of refrigerants into an approved container.
91
What is the latent heat of fusion (solid to a liquid)?
144 Btu's
92
If a capillary tube evaporator coil is purchased, can it's size be increased or decreased?
No
93
What is important about the type of copper used in refrigeration?
It needs to be charged with nitrogen, cleaned, and dried
94
What is the location of the TXV valve?
Liquid line near evaporator coil
95
What is the location of the temperature sensing bulb of the TXV valve?
Refrigeration flow coil out of the evaporator
96
What is the location of the fixed orifice?
Refrigeration flow coil out of the evaporator
97
Where is the location of the capillary tube?
Refrigeration flow coil out of the evaporator

Air Conditioning (2 decks)

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