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Term 2: Ammonia > Chilled water systems: Exam 2 > Flashcards

Chilled water systems: Exam 2 Flashcards

1
Q

Which of the following components are always installed in a chiller system?

  1. compressor suction line and chilled liquid lines
  2. evaporator coil and suction line
A

1.

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2
Q

Which of the following is NOT true about chillers using a water-cooled condenser in combination with a cooling tower?

  1. same water circuit is used for both the condenser and evaporator
  2. forced air fans are used in the cooling tower to aid evaporation
A

1.

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3
Q

The ARI standard recommends that chiller evaporators operate at a ___ chilled water temp

  1. 34F
  2. 44F
  3. 75F
A
  1. 44F
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4
Q

The ARI standard recommends that chiller evaporators operate at a ___ condenser inlet water temp

  1. 34F
  2. 44F
  3. 75F
  4. 85F
A

85F

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5
Q

Which of the following statements about low pressure chillers is false?

  1. they are the most identical to high-pressure chillers
  2. they are more heavily constructed than high-pressure chillers
A

2.

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6
Q

Which of the following statements about purge units is false?

  1. their function is to maintain a system free of air and moisture
  2. they run almost continuously to pump out noncondensables
A

2.

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7
Q

Scroll compressor chillers

  1. are positive displacement compressors
  2. are welded-hermetic units
  3. have capacities in the 10-25 ton range
  4. all of the above
A
  1. all of the above
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8
Q

Which of the following is NOT true about two stage compressor units?

  1. they have less piping due to the elimination of a second chiller and pumps
  2. refrigerant from the evaporator passes through the economizer before it enters the compressor
A

2.

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9
Q

Which of the following statements about the lubrication system of a centrifugal unit is false?

  1. it can deliver oil to the critical parts of the compressor and gearbox before the compressor motor begins spinning
  2. the oil is mixed with the refrigerant through the use of a sump pump
A

2.

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10
Q

The capacity of a centrifugal compressor is controlled by adjusting guide ______ at the centre of the impeller eye

A

vanes

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11
Q

Which of the following statements about evaporative condensers is true?

  1. it is a housing or shed into which air is drawn
  2. they are used when tap water cannot be used
  3. makeup water has added to replace water lost by evaporation
  4. all of the above
A

all of the above

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12
Q

T or F

As a chiller circulates water through a building, the water absorbs and removes heat from the conditioned areas

A

true

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13
Q

T or F

The compressor, condenser, metering device, and evaporator in a chiller are smarter than those in a standard air conditioner

A

false

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14
Q

T or F

The condenser used in chiller systems can be evaporative, air-cooled, or water-cooled

A

true

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15
Q

T or F

High pressure chillers are typically centrifugal chillers charged with R-123

A

false

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16
Q

T or F

Low pressure chillers are compression chillers that operate under low pressures

A

false

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17
Q

T or F

The type of compressor used in a chiller system depends on the number of tons of air conditioning needed

A

true

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18
Q

T or F

Centrifugal compressor chillers are used in large comfort cooling installations due to their cost effectiveness for large loads

A

true

19
Q

T or F

Centrifugal compressor chillers use high-pressure refrigerants, such as R-123

A

false

20
Q

T or F

The evaporator in a system with a centrifugal compressor operates at above-atmospheric pressure

A

false

21
Q

T or F

Chiller systems are expensive due to high energy consumption

A

false

22
Q

T or F

Centrifugal compressor chillers use centrifugal force to compress the refrigerant and move it from the low side to the high side of the system

A

true

23
Q

T or F

A closed-drive motor used in a chiller system is cooled by the air in the room

A

false

24
Q

The two main type of chillers are compression chillers and _________ chillers

A

absorption

25
Q

A fluid that is circulated at absorb heat from a conditioned area is called a _______ refrigerant

A

secondary

26
Q

A cooling system that uses a loop of chilled water to provide cooling to a conditioned area is a _____ water system

A

chilled water system

27
Q

A system in which the refrigerant is fed into the evaporator at the same rate it evaporates is a direct _______ system

A

direct expansion system

28
Q

An all inclusive system is called a _____ central air conditioning system

A

unitary

29
Q

A system mounted on a concrete pad adjacent to the building is an _____ air-conditoning unit

A

outdoor

30
Q

A system in which the condensing unit is located away from the evaporator is a ____ system

A

split

31
Q

A system in which the components are purchased separately and assembled on site is a ____-erected air-conditioning system

A

field erected air conditioning system

32
Q

Uses drafts from fans to aid in evaporating a water sit on and around the refrigerant-carrying tubes is an ________ condenser

A

evaporative

33
Q

A cooling system that uses a loop of chilled water instead of a forced air to provide cooling is a _____ system

A

chiller

34
Q

Fluid that is circulated to absorb heat from a conditioned area is a _______ refrigerant

A

secondary

35
Q

Absorbs heat from the secondary refrigerant and rejects heat from the system

A

primary refrigerant

36
Q

Component into which refrigerant is fed at the same rate that it evaporates Is a _____ expansion evaporator

A

direct expansion

37
Q

A auxiliary component used to remove noncondesables is a _____ unit

A

purge

38
Q

Type of chiller used primarily for commercial and industrial process cooling is a ____-pressure chiller

A

high pressure chiller

39
Q

Why is water commonly used as a secondary refrigerant in chillers designed for comfort cooling?

A

cheap to use and non toxic

40
Q

What function does primary refrigerant in a chiller system serve?

A

absorbs heat from secondary refrigerant

41
Q

What is a purge unit?

A

removes non condensables

42
Q

What purposes do inlet guide vanes serve in a centrifugal compressor?

A

control amount of refrigerant entering compressor

43
Q

How does an evaporative condenser function?

A

uses drafts from fans to evaporate spray

Term 2: Ammonia (21 decks)

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