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RAC 40 > unit 3 review(book) > Flashcards

unit 3 review(book) Flashcards

1
Q

Ice melts in ice boxes because

A. Heat flows through the insulated walls
B. Heat flows through the doorway when it is opened
C. Heat is moved into the box when warm food is placed in it
D. All of the above

A

D. All of the above

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2
Q

High-temperature refrigeration is that produced by

A. Heat from a furnace
B. An air-conditioning system
C. The vegetable cooling system of a refrigerator
D. The freezer section of a refrigerator

A

B. An air-conditioning system

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3
Q

A ton of refrigeration is equal to

A. 1 ton of ice
B. 288,000 btu/24 h
C. 144 btu/h
D. A larger refrigerator

A

B. 288,000 btu/24 h

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4
Q

The evaporator in a refrigeration system

A. Meters the refrigerant
B. Condenses the refrigerant
C. Is the component where refrigerant boils and absorbs heat
D. Compress the vaporized refrigerant

A

C. Is the component where refrigerant boils and absorbs heat

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5
Q

The compressor in a refrigeration system

A. Compresses the refrigerant
B. Pumps the refrigerant throughout the system
C. Both a&b
D. None of the above

A

C. Both a&b

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6
Q

The condenser

A. Rejects the heat from the refrigerant
B. Meters the refrigerant throughout the system
C. Causes superheat in the refrigerant
D. All of the above

A

A. Rejects the heat from the refrigerant

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7
Q

Only liquid refrigerant should enter the metering device

A. True
B. False

A

A. True

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8
Q

Reciprocating compressors have

A. A piston and a cylinder
B. Two scrolls that mesh together
C. A rotor to compress the refrigerant
D. A large fan-type compressor component

A

A. A piston and a cylinder

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9
Q

R-22 is a refrigerant most commonly used in _________ systems

A. Residential air-conditioning
B. Light commercial refrigeration
C. Industrial refrigeration
D. Household refrigeration

A

A. Residential air-conditioning
Or
B. Light commercial refrigeration

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10
Q

R-134a is a refrigerant most commonly used in _________ systems

A. Medium-temperature
B. Residential air-conditioning
C. Primarily low-temperature
D. All of the above

A

A. Medium-temperature

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11
Q

The cylinder color code for r-410a is

A. Rose
B. White
C. Yellow
D. Green

A

A. Rose

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12
Q

The cylinder code for r-134a is

A. Red
B. Yellow
C. Light blue
D. Green

A

C. Light blue

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13
Q

The cylinder color code for r-404a is

A. Orchid
B. Orange
C. Purple
D. Green

A

B. Orange

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14
Q

The cylinder color code for r-22 is

A. Orchid
B. White
C. Purple
D. Green

A

D. Green

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15
Q

Good ventilation is important when working around refrigeration equipment because modern refrigerants

A. Are toxic and can poison you
B. Have a very unpleasant odor
C. May get on your skin and cause a rash
D. Are heavier than air and may displace the oxygen around you

A

D. Are heavier than air and may displace the oxygen around you

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16
Q

The boiling point of a refrigerant should be low enough at atmospheric pressure so that low temperatures can be reached and the refrigeration system will

A. Not overheat
B. Not explode
C. Not go into a vacuum
D. Not ice up

A

C. Not go into a vacuum

17
Q

It is believed that certain refrigerants such as CFCs and HCFCs, when allowed to escape into the atmosphere, will

A. Destroy the hydrogen layer and allow more of the suns rays to overheat the earth
B. Deplete the stratospheric ozone layer and allow harmful ultraviolet rays from the sun to reach the earth
C. Reduce the nitrogen content of the air surrounding the earth
D. Reduce the carbon dioxide necessary for plant life

A

B. Deplete the stratospheric ozone layer and allow harmful ultraviolet rays from the sun to reach the earth

18
Q

It is important for technicians to recover refrigerant so that they

A. Will not be released into the atmosphere
B. May be used again
C. May be reclaimed for future use
D. All of the above

A

D. All of the above

19
Q

Enthalpy describes

A. The moisture content in air
B. The amount of refrigerant needed in a system
C. The amount of heat a substance contains from some starting point
D. The amount of harmful ultraviolet rays in the atmosphere

A

C. The amount of heat a substance contains from some starting point

20
Q

A near-azeotropic refrigerant blend replacing r-22 in residential and commercial air-conditioning applications is

A. R-404a
B. R-407c
C. R-410a
D. R-134a

A

C. R-410a

21
Q

A refrigerant that has properties very similar to r-12 and is used primarily in medium and high-temperature refrigeration applications, refrigerators and freezers, and automotive air-conditioning is

A. R-22
B. R-134a
C. R-404a
D. R-407c

A

B. R-134a

22
Q

A refrigerant replacing r-502 in low and medium temperature refrigeration applications, which is a near-azeotropic refrigerant blend with a small temperature glide, is

A. R-404a
B. R-407c
C. R-134a
D. R-500

A

A. R-404a

23
Q

The cylinder color code for r-404a is

A. Bright green
B. Rose
C. Aqua
D. Orange

A

D. Orange

24
Q

Near-azeotropic refrigerant blends all exhibit some

A. Temperature glide and fractionation
B. Oil problems
C. High boiling points
D. Low condensing pressures

A

A. Temperature glide and fractionation

25
Q

The quantity of heat expressed in Btu/lb that the refrigerant absorbs from the refrigerated space to produce useful cooling is

A. A calorie
B. Enthalpy
C. The net refrigeration effect
D. A degree

A

C. The net refrigeration effect

26
Q

The amount of heat, in Btu/lb that is given off by the system in the discharge line and the condense is referred to as the

A. Net refrigeration effect
B. Heat of work
C. Heat of compression
D. Total heat of rejection

A

D. Total heat of rejection

27
Q

When the portion of a pressure/Enthalpy diagram is beneath the saturation curve, then

A. The refrigerant is at a constant temperature
B. The refrigerant is at a constant pressure
C. The refrigerant follows a temperature/pressure relationship
D. The refrigerant is 100% vapor

A

C. The refrigerant follows a temperature/pressure relationship

28
Q

According to the pressure/Enthalpy chart, as refrigerant flows through the compressor

A. The pressure, temperature, and heat content of the refrigerant all increase
B. The pressure and temperature of the refrigerant increase, while the heat content of the refrigerant decreases
C. The pressure and heat content of the refrigerant decreases
D. The pressure, temperature, and heat content of the refrigerant all decrease

A

A. The pressure, temperature, and heat content of the refrigerant all increase

29
Q

Lines of constant pressure on a pressure/Enthalpy diagram are referred to as

A. Isotherms
B. Isometrics
C. Isobars
D. Glide lines

A

C. Isobars

30
Q

Lines of constant temperature on a pressure/Enthalpy diagram are referred to as

A. Isotherms
B. Isometrics
C. Isobars
D. Fractionation lines

A

A. Isotherms

RAC 40 (10 decks)

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