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Air 121 > Test Questions > Flashcards

Test Questions Flashcards

1
Q

All matter has

A

MASS

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2
Q

The density of a substance

A

Describes its mass to volume relationship.

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3
Q

Specific volume is used to what ?

A

Indicate the volume that a specific weight of gas will occupy

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4
Q

How many watts of electrical power are equal to 1 hp

A

746

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5
Q

Gas molecules travel

A

every direction ( d all the above

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6
Q

1 watt equals ?

A

3.413 BTUs

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7
Q

If water weighs 8.33 pounds per gallon it will take how many BTUs to raise the temperature of 4 gallons of water from 70°F to 72°F

A

66.7

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8
Q

Temperature is defined as what

A

The level of heat

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9
Q

One British thermal unit will raise the temperature of 1 pound of water how many degrees Fahrenheit

A

1 degree Fahrenheit

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10
Q

Ice melts in ice boxes because

A

All of the above

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11
Q

A ton of refrigeration is equivalent to how many BTUs?

A

288,000 BTU/24 hour

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12
Q

The evaporator in the refrigeration system is

A

The component where refrigerant boils and absorbs heat.

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13
Q

The compressor in a refrigeration system does what

A

It compresses the refrigerant and pumps the refrigeration through the system.

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14
Q

The Condenser

A

Rejects heat from the refrigerant.

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15
Q

Enthalpy describes

A

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

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16
Q

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

A

The Net refrigeration effect

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17
Q

The amount of heat in the BTU/lb that is given off by the system in the discharge line and the condenser is referred to as the what?

A

Total heat of rejection

18
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.

19
Q

One ton of refrigeration is

A

12000 BTU/hr

20
Q

In which direction does heat flow ?

A

From a warm substance to a cold substance.

21
Q

An increase in sensible heat causes what ?

A

A higher thermometer reading.

22
Q

A change in latent heat causes a what ?

A

A change in phase or state

23
Q

When Heat transfers by conduction it ….

A

Moves from molecule to molecule.

24
Q

When heat is transferred by convection it…

A

Is transported from one place to another by air or fluid

25
Q

When heat is transferred by radiation it

A

Moves through space air air and heats solid objects as.

26
Q

PSIG is equal to ?

A

PSIA - 14.696

27
Q

The latent heat of fusion for a water to ice transformation is what?

A

144 BTU/lb

28
Q

Condensing spread is calculated by how?

A

Saturated conditioning temp - outdoor ambient (Normally 15-30 degrees Fahrenheit)

29
Q

Approach Temp is calculated how ?

A

Liquid Line temperature - Outdoor ambient (normally 3 -15 )

30
Q

Subcooling temp is calculated how ?

A

Saturated condensing temp - liquid line temp.

31
Q

Evaporating spread is calculated by how ?

A

Entering air - saturated evaporating temp

32
Q

Super heat spread

A

Suction line temp-saturated evaporating temperature. (Normally 12+)

33
Q

What are the High side temperature readings ?

A

Condensing spread, Approach temperature , Subcooling Temperature

34
Q

What are the Low side temperature readings ?

A

Evaporating spread, Superheat

35
Q

Whose law states that the volume of a gas varies inversely with absolute pressure, as long as the temperature remains constant?

A

Boyle’s

36
Q

Condenser does what 3 things?

A
  1. ) De-superheat
  2. ) Condenses
  3. ) Subcooling
37
Q

How many BTUs are required to change 6 lbs of ice at 20 degrees Fahrenheit to steam at 220 ?

A

7830 BTUs

38
Q

Specific heat of ICE and steam

A

.5 BTU/lb per degree

39
Q

Specific heat of water

A

1 BTU/lb/degrees farenheit

40
Q

Specific heat of vaporization is how many BTUs?

A

970 BTUs

Air 121 (3 decks)

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