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Refrigeration Flashcards

1
Q

Gas plant refrigeration uses what type of refrigerant

A

Propane

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2
Q

Industrial liquid over feed systems use what type of refrigerant

A

Ammonia

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3
Q

Matter is made up of what three molecules

A

Gasses
Liquids
And solids

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4
Q

Define radiation

A

Radiation is a vaccume a heat transfer by electro magnetic waves

Warm objects radiate more heat than colder ones with the overall effect that cold objects gain more heat by radiation than warm objects

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5
Q

Convection is

A

Heat transfer by moving matter.

When heated a fluid decreases in density, and the warm fluid that is high density pushes the warm fluid upwards

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6
Q

Define latent heat

A

It is added or removed heat that pulls the molecule apart (ie ice melting)

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7
Q

At what point does water turn into steam

A

Once it reaches 100c (212f)

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8
Q

What are the two types of heat

A

Latent heat

Sensible heat

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9
Q

Define sensible heat

A

can be measured and is the measure of vibration rate of molecules

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10
Q

Define energy

A

The capacity to do work and may consist as

potential

Or

Kinetic

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11
Q

Potential energy means what

A

Means that it is at rest and capable of doing work

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12
Q

What are the typo main types of energy conversion

A

Electrical converted to mechanical

Mechanical converted to heat

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13
Q

A liquid does what as it boils

A

Obsorbs heat

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14
Q

A vapour does what as it condensates

A

Releases heat

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15
Q

The quality of heat required to completely vapourize one Kilo of liquid(at boiling temp is called

A

Latent heat of vaporization

Reverse the process and you have

Latent heat of condensation

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16
Q

What temperature does propane boil at

A

-42*c under the pressure of one atmosphere

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17
Q

What temperature does pure ammonia boil at

A

-33*c under the pressure of one atmosphere

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18
Q

The low pressure side of a refrigeration cycle starts where

A

From the outlet of the metering device and continues as the refrigerant flows to the inlet of the compressor

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19
Q

The high pressure side of a refrigeration cycle stats where

A

From the outlet of the compressor and continues as the refrigerant flows to the inlet of the metering device

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20
Q

Circulating refrigerant has four major processes

They are. in this order

A

Condensation
expansion
evaporation
compression

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21
Q

What is the main purpose of the compressor in the refrigeration system

A

The compressor circulates and maintains a low pressure in the evaporator

Simultaneously it maintains a high pressure in the condenser

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22
Q

What is the most common compressor in refrigeration

A

Reciprocating compressor

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23
Q

What is the main purpose of the condenser in the refrigeration system

A

Reject heat from the circuit

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24
Q

What is the main purpose of the metering device in the refrigeration system

A

Throttles and regulates the flow of refrigerant, also maintains the pressure difference between evaporator and condenser

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25
Q

Aside from oil what is another substance that compressors should never pump

A

Liquid refrigerant as it resists compression

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26
Q

What two reciprocating compressors are generally used in refrigeration

A

Screw

Centrifugal

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27
Q

The temperature above the condensing or boiling temperature of the refrigerant is called

A

Supper heat

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27
Q

What heat transfers by moving matter, separating one from the other hirer on too colder on the bottom

A

Convection

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28
Q

What transfer is caused by physical contact

A

Conduction

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29
Q

The greatest heat transfer in a refrigeration system occurs in the

Evaporator
Or
Condenser

A

Evaporator takes in mor BTUs than condenser can give off

30
Q

Liquid overfeed at the evaporator results in a mixture of liquid and gaseous refrigerant leaving the evaporator. What is used to prevent the liquid from entering the compressor suction

A

A low pressure receiver

Liquid settles on the bottom while compressor suction suck the vapour from the top

31
Q

What effect does lowering the boiling point have on a liquid

A

Lowers the boiling point

32
Q

Why is it important refrigerant has a low boiling point

A

Lower boiling point means it can reach a lower pressure

34
Q

in the flooded system, the brine tubes are immersed

A

liquid refrigerant

35
Q

what does liquid-feed mean?

A

low pressure refrigerant is stored in a tank where is can be pumped where it can be pumped through evaporators again without having to go through an entire compression cycle

36
Q

why is liquid overfeed system commonly used in industrial applications

A

It can have multiple evaporators for one system

37
Q

what insulation category does Cellular glass fall into

A

Cryogenic

38
Q

what insulation category does fiberglass, rock-wool, and Vermiculite fall into

A

Thermal

39
Q

what insulation category do bricks and Gunnite mixture fall into

A

Refaractory

40
Q

ammonia flooded systems require an oil separator because

A

the oil does not return to the compressor

41
Q

liquid levels in a liquid overfeed low pressure receiver is monitored/controlled by

A

float switch

42
Q

lithium bromide (absorption) refrigerant uses ___________energy to produce the refrigerant effect

A

Heat

43
Q

what is used as the refrigerant in the lithium bromide absorption system

A

water

44
Q

what shut down cycle must a chiller run through to prevent crystallization

A

dilution cycle

45
Q

in an abortion system the heat ex changer serves what vital function

A

heats diluted solution and cools the concentrated solution

46
Q

the metering device on a compression refrigeration system can be what three devices

A

capillary tube, fixed orifice, or a thermostatically controlled expansion valve.

47
Q

boiling temp of a liquid, and condensing temp of a vapour can be at the same temperature as long as

A

pressure exerted on the fluid is the same

48
Q

as refrigerant turns into a vapor it absorbs what kind of heat

A

latent heat of vaporization

49
Q

when refrigerant condenses into a liquid the vapor rejects what type of heat

A

latent heat of condensation

50
Q

1 BTU = The amount of heat required to

A

raise 1 LB of H2O 1*F

51
Q

The lower pressure side of a metering device =

A

95%liquid 5% gas

52
Q

if pressure on water was lowered water would boil at a higher or lower temperature

A

lower temperature

53
Q

condenser pressure is controlled by

A

condensing capacity

54
Q

what is a heat exchange that draws heat into the vapor compression cycle

A

the Evaporator draws heat into the vapor compression cycle

55
Q

systems are designed to minimize or illuminate pressure through the

A

evaporator

56
Q

what is the purpose of the liquid line dryer system

A

removes small dirt particles, moisture, and acid

57
Q

what two things must a refrigerant do in low pressure, low temperature

A

absorb heat, evaporate (boil),

58
Q

in a refrigeration system, pressure on the low side is controlled by

A

compressor capacity

59
Q

in a refrigeration system, pressure on the high side is controlled by

A

condenser capacity

60
Q

name a heat exchange used in vapor compression refrigeration systems

A

shell and tube

61
Q

in which component is thermal energy absorbed by the refrigerant

A

evaporator

62
Q

what is the name for heat energy that causes temperature change

A

sensible heat

63
Q

in which component is refrigerant de-super heated, condensed and sub-cooled?

A

conensor

64
Q

what effect does the compressor have on the boiling/condensing temperature of the refrigerant

A

raises the boiling point

65
Q

what is the refrigerant used in lithium bromide Chillers

A

water

66
Q

what effect does the pressure decrease have on the boiling point of a liquid

A

it Decreases

67
Q

what id the purpose of a compressor in a refrigeration system

A

create low pressure in the evaporator, high pressure in the confessor

68
Q

why must pressure be raised before sending refrigerant to the condenser

A

to raise the condensing point so gas can become liquid

69
Q

what happens to refrigerant in the evaporator

A

heat energy is absorbed and it changes into a gas

70
Q

what is an auto purge used for

A

to vent non condescension gas from a refrigeration system

71
Q

what is a liquid overfeed system

A

an excess of liquid is supplied to the evaporator

72
Q

what type of condenser uses air flow and water evaporation

A

evaporator

73
Q

what is a hermetically sealed compressor

A

its a non serviceable vessel that holds the compressor, compressor driver, oil and refrigerant, and requires no shaft seal for compressor

74
Q

what is the upside to liquid over feed

A

they can use multiple evaporators for multiple different temperature applications

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