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PSAEIV-ABE BRM > AREA III - Refrigeration and Air conditioning > Flashcards

AREA III - Refrigeration and Air conditioning Flashcards

1
Q

It is the process of cooling

A

Refrigeration

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2
Q

It is the process of treating air to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space

A

Comfort air conditioning

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3
Q

Provides a heat transfer surface through which heat can pass from the refrigerated space or product into the vaporizing refrigerant

A

Evaporator

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4
Q

Conveys the low-pressure vapor from the evaporator to the suction inlet of the compressor

A

Suction line

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5
Q

Removes the vapor from the evaporator and raises the temperature and pressure of the vapor to a point such that the vapor can be condensed with normally available condensing media

A

Vapor compressor

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6
Q

Delivers the high pressure, high-temperature vapor from the discharge of the compressor to the condenser

A
  1. “Hot gas” or discharge line
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7
Q

Provides a heat transfer surface through which heat passes from the hot refrigerant vapor to the condensing medium

A

Condenser

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8
Q

Provides storage for the condensed liquid so that a constant supply of liquid is available to the evaporator as needed

A

Receiver tank

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9
Q

Carries the liquid refrigerant from the receiver tank to the refrigerant flow control

A

Liquid Line

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10
Q

Meters the proper amount of refrigerant to the evaporator and reduces the pressure of the liquid entering the evaporator so that the liquid will vaporize in the evaporator at the desired low temperature

A

Refrigerant flow control

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11
Q

The substance employed as the heat absorber or cooling agent

A

refrigerant

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12
Q

the absorbed heat causes an increase in the temperature of the refrigerant

A

Sensible

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13
Q

the absorbed heat causes a change in the physical state of the refrigerant
(either melting or vaporizing)

A

Latent

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14
Q

Medium of heat transfer which absorbs heat by evaporating at a low
temperature and gives up heat by condensing at a high temperature and pressure

A

Refrigerant

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15
Q

The principal use of this refrigerant is in the air-cycle refrigeration unit for aircraft

A

Air

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16
Q

A refrigerant used in large industrial and low-temperature
installations

A

Ammonia

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17
Q

A refrigerant with high horsepower requirements and high condensing pressures that has been used on low - temperature cycle in a cascade system.

A

Carbon dioxide

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18
Q

A refrigerant suitable for service in centrifugal compressors.

A

Refrigerant 11

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19
Q

Two most-used refrigerants in
centrifugal compressor system

A

R11 and R113

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20
Q

A refrigerant that is most widely used refrigerant. It is used primarily with
reciprocating compressors for service in household refrigeration appliances, commercial and industrial air conditioning, and in a multitude of other types of refrigeration systems

A

Refrigerant 12

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21
Q

A refrigerant similar to R12 that is also nontoxic and has a low power requirement per ton.

A

Refrigerant 22

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22
Q

A refrigerant that possesses desirable properties, having convenient operating pressures, low power requirement per ton, and is nontoxic and noncorrosive.

A

Refrigerant 12

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23
Q

A refrigerant that is competitive with ammonia in industrial low-temperature systems in cases where the toxicity of the refrigerant is of concern.

A

Refrigerant 22

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24
Q

Examples of secondary refrigerants

A

brines and antifreezes

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25
Q

Two of the most popular brines

A

calcium chloride and sodium chloride solutions

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26
Q

It is defined as the uncontrolled entry of unconditioned outside air directly into the building, resulting from natural forces, e.g., wind and buoyancy due to the temperature difference between inside and outside.

A

Infiltration

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27
Q

Heat gain due to the release of energy within a space

A

Internal load

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28
Q

It is defined as air intentionally brought into the building by mechanical means.

A

Ventilation

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29
Q

It is a mechanical mixture of gases and water vapor

A

Air

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30
Q

It is the temperature at which the water vapor in the air is saturated

A

Dew Point Temperature

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31
Q

It is the water vapor in the air

A

Humidity

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32
Q

It is the mass of water vapor per unit volume of air

A

Absolute humidity or vapor density

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33
Q

Ratio of the actual partial pressure exerted by the water vapor in any
volume of air to the partial pressure that would be exerted by the water vapor if the water vapor in the air is saturated at the temperature of the air

A

Relative humidity

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34
Q

It is also called as specific humidity, is an expression of the mass of water
vapor per unit mass of dry air

A

Humidity ratio

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35
Q

It is also called as percentage humidity, is the ratio of the mass of water vapor in the air per unit mass of dry air to the mass of water vapor required for
saturation of the same air sample.

A

Saturation ratio

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36
Q

Temperature as measured by an ordinary dry bulb thermometer

A

Dry bulb temperature of the air

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37
Q

Temperature as measured by a wet bulb thermometer

A

Wet bulb temperature of the air

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38
Q

An ordinary thermometer whose bulb is enclosed in a wetted
cloth sac or wick.

A

wet bulb thermometer

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39
Q

It is the sum of the enthalpy of the dry
air and the enthalpy of the water vapor

A

Enthalpy

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40
Q

The difference between the dew point and dry bulb temperature of air

A

Degrees of superheat

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41
Q

The study of the properties of the mixtures of air and water vapor

A

Psychrometry

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42
Q

When the condition of the mixture lies on this line the air is said to be
saturated

A

Saturation line

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43
Q

Refers to a rate of heat transfer attributable only to a change in dry-bulb temperature of the air.

A

Sensible heating or cooling

44
Q

It may be adiabatic or with addition of heat

A

Humidification

45
Q

Results in a reduction of both the dry-bulb temperature and the humidity ratio

A

Cooling and dehumidification

46
Q

the water vapor from the air is absorbed or adsorbed by a hygroscopic material

A

Chemical dehumidification process

47
Q

4 most commonly used valves

A

shutoff, backpressure, solenoid and backseating.

48
Q

A valve installed in the line to block flow completely when it is closed

A

shutoff valve

49
Q

A valve installed in the suction line to
maintain a sufficiently high pressure in an evaporator to prevent freezing or excessive dehumidification of air in an air cooling coil.

A

back-pressure valve or evaporator-pressure regulator

50
Q

A valve that is electrically powered magnetic valves which serve as automatic shutoff valves

A

Solenoid valves

51
Q

It recovers as much of this oil as possible before it goes through the condenser and collects in the
evaporator

A

Oil separator

52
Q

These are installed in the suction and discharge lines to reduce the
transmission of vibration from the compressor

A

Vibration eliminators

53
Q

It causes irritating noise and weaken
the solder connections in the piping

A

Vibrations

54
Q

It contains desiccants such as silica gel or activated alumina which adsorb moisture.

A

Driers

55
Q

It prevents foreign particles from flowing through the refrigerating system

A

Filters

56
Q

A short transparent fitting that allows the flow of refrigerant to be viewed

A

Liquid indicators

57
Q

Its purpose is to heat the vapor coming from the evaporator while it subcools liquid flowing between the condenser and the expansion valve

A

Heat exchanger

58
Q

A vessel that stores liquid refrigerant

A

Liquid receiver

59
Q

It prevents suction vapor from carrying slugs of liquid to the compressor from the evaporator.

A

Liquid accumulator

60
Q

It removes air from the system

A

Purger

61
Q

Three common methods of defrosting coils

A

use warm air,
water and hot gas

62
Q

A type of fan that consists of a wheel or rotor within a scroll spiral type
housing

A

Radial flow or centrifugal fan

63
Q

it has a large number of blades, i.e. up to 60, narrow in the radial dimension but wide parallel to the shaft and facing forward in the direction of rotation like a scoop.

A

Forward-curved-blade

64
Q

It has about 12 blades, essentially flat and tilted backward from the direction of wheel rotation. It is a high-speed type of fan with a self-limiting horsepower characteristic. It is the most efficient and more expensive.

A

Backward-curved-blade

65
Q

it has a smaller number of blades – from 6 to 20 – and the blades are essentially in a plane radiating from the shaft. The blades are normally about 2 to 3 times as long radially as they are wide.

A

Straight or double-curved fan

66
Q

Airflow is parallel to the shaft or axis

A

Axial-flow or Propeller fan

67
Q

This is suited for ventilation of rooms and air ducts of low resistance. This is characterized by excessive noises at high speeds.

A

Propeller

68
Q

It is distinguished by large hubs and short blades, in addition to stationary
straight vanes on the discharge sides of the fan to prevent rotation or swirling of the air.

A

Vane-axial

69
Q

This is similar to a vane-axial fan except that it does not contain guide vanes. It is simpler and somewhat less efficient than the vane-axial.

A

Tube-axial

70
Q

A heat-operated unit, which uses a refrigerant that, is alternately absorbed and liberated by the absorbent

A

Absorption Refrigeration

71
Q

A cylindrical vessel designed to trap any refrigerant liquid, which may not have changed to gas in the evaporator, from entering the suction line to the compressor

A

Accumulator

72
Q

Which transfers energy from a low-level temperature to a high level temperature, requiring an additional external work for its operation

A

Carnot Refrigeration Cycle

73
Q

Its operation is that the incoming gas enters the eye of the spinning impeller and is thrown by centrifugal force to the periphery of the impeller importing a high velocity to the gas, thus builds up the pressure.

A

Centrifugal Compressor

74
Q

The ratio of useful refrigeration (or refrigerating effect) to the net work (or work of compression).

A

Coefficient of Performance

75
Q

This unit condenses the high-pressure vapor (refrigerant) back into a liquid state so that it can be reused in the refrigeration cycle.

A

Condenser

76
Q

It is a cooling equipment for refrigeration or an air conditioning system where water is cooled by contacting it with air and evaporating some of the water

A

Cooling Tower

77
Q

Temperature at which the moisture (water vapor) in the air will begin to condense out of the air when the air is cooled

A

Dewpoint Temperature

78
Q

Temperature of air measured with
a standard thermometer with a minimum relative motion between the dry thermometer bulb
and the surrounding air.

A

Dry-bulb Temperature

79
Q

A type of evaporator when a portion of its area is used for superheating
the refrigerant.

A

Dry Evaporator

80
Q

A solid carbon dioxide which when heated at atmospheric pressure, the solid
transforms directly into vapor

A

Dry Ice

81
Q

A companion device for conserving water with the cooling tower.

A

Evaporative Condenser

82
Q

It is a heat exchanger, which transfers heat from the substance being cooled to
a boiling refrigerant

A

Evaporator

83
Q

It is a primary refrigerant such as Freon 12 or Freon 22, under the trademark of Freon Products.

A

Freon

84
Q

Quantity of heat that will pass

A

Heat of Respiration

85
Q

Measure of the proportion of vapor present

A

Humidity

86
Q

The weight of vapor interspersed per pound of dry air

A

Humidity Ratio

87
Q

Volume of 1 kg dry gas plus its contained vapor

A

Humid Volume

88
Q

Load added to the cooling equipment when cooled air is displaced by outdoor air entering through the cracks around doors and windows when door opens.

A

Infiltration Load

89
Q

Heat loads principally coming from people, infiltration air, ventilation air and moisture-releasing appliances

A

Latent Load

90
Q

Occurs when the temperature drops below the dew-point temperature of the air

A

Moisture Condensation

91
Q

Amount of heat that must be removed from the product to lower its temperature to the room in which it is to be stored

A

Product Load

92
Q

Measurement of physical properties of gas mixture

A

Psychrometrics

93
Q

Chart of gas mixture properties

A

Psychrometric Chart

94
Q

The study of properties of mixtures of air and water vapor

A

Psychrometry

95
Q

Removing of air from the refrigeration system

A

Purging

96
Q

A type of compressor consisting of a piston moving back and forth in a cylinder with suction and discharge valves arranged to allow pumping to take
place

A

Reciprocating Compressor

97
Q

The ratio of the partial pressure of the water vapor in saturated air at the same temperature

A

Relative Humidity

98
Q

It is a positive-displacement machine with shaft, blade, and roller as its moving parts in the compression.

A

Rotary Compressor

99
Q

It is a refrigerating system using steam as a refrigerant, which expands through a converging-diverging nozzle and rushes out a supersonic speed

A

Steam Jet Refrigeration

100
Q

It is vapor pressure at a temperature above the boiling point when the volume is confined under pressure.

A

Steam Pressure

101
Q

It is a change of phase from solid into a vapor, which may provide refrigeration

A

Sublimation

102
Q

The insulating ability of a material or the resistance of the material to the flow of heat through it.

A

Thermal Resistance

103
Q

It is the unit of refrigeration capacity requiring to freeze one (1) ton of
water at 32°F into ice at 32°F in one (1) day equivalent to 200 Btu/min or 12,000 Btu/hr.

A

Ton of Refrigeration

104
Q

The total heat energy in the air

A

Total Heat Content

105
Q

When the water molecules in the air exert a particular pressure

A

Vapor Pressure

PSAEIV-ABE BRM (9 decks)

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