Chilled water systems: Exam 2 Flashcards
Which of the following components are always installed in a chiller system?
- compressor suction line and chilled liquid lines
- evaporator coil and suction line
1.
Which of the following is NOT true about chillers using a water-cooled condenser in combination with a cooling tower?
- same water circuit is used for both the condenser and evaporator
- forced air fans are used in the cooling tower to aid evaporation
1.
The ARI standard recommends that chiller evaporators operate at a ___ chilled water temp
- 34F
- 44F
- 75F
- 44F
The ARI standard recommends that chiller evaporators operate at a ___ condenser inlet water temp
- 34F
- 44F
- 75F
- 85F
85F
Which of the following statements about low pressure chillers is false?
- they are the most identical to high-pressure chillers
- they are more heavily constructed than high-pressure chillers
2.
Which of the following statements about purge units is false?
- their function is to maintain a system free of air and moisture
- they run almost continuously to pump out noncondensables
2.
Scroll compressor chillers
- are positive displacement compressors
- are welded-hermetic units
- have capacities in the 10-25 ton range
- all of the above
- all of the above
Which of the following is NOT true about two stage compressor units?
- they have less piping due to the elimination of a second chiller and pumps
- refrigerant from the evaporator passes through the economizer before it enters the compressor
2.
Which of the following statements about the lubrication system of a centrifugal unit is false?
- it can deliver oil to the critical parts of the compressor and gearbox before the compressor motor begins spinning
- the oil is mixed with the refrigerant through the use of a sump pump
2.
The capacity of a centrifugal compressor is controlled by adjusting guide ______ at the centre of the impeller eye
vanes
Which of the following statements about evaporative condensers is true?
- it is a housing or shed into which air is drawn
- they are used when tap water cannot be used
- makeup water has added to replace water lost by evaporation
- all of the above
all of the above
T or F
As a chiller circulates water through a building, the water absorbs and removes heat from the conditioned areas
true
T or F
The compressor, condenser, metering device, and evaporator in a chiller are smarter than those in a standard air conditioner
false
T or F
The condenser used in chiller systems can be evaporative, air-cooled, or water-cooled
true
T or F
High pressure chillers are typically centrifugal chillers charged with R-123
false
T or F
Low pressure chillers are compression chillers that operate under low pressures
false
T or F
The type of compressor used in a chiller system depends on the number of tons of air conditioning needed
true
T or F
Centrifugal compressor chillers are used in large comfort cooling installations due to their cost effectiveness for large loads
true
T or F
Centrifugal compressor chillers use high-pressure refrigerants, such as R-123
false
T or F
The evaporator in a system with a centrifugal compressor operates at above-atmospheric pressure
false
T or F
Chiller systems are expensive due to high energy consumption
false
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
true
T or F
A closed-drive motor used in a chiller system is cooled by the air in the room
false
The two main type of chillers are compression chillers and _________ chillers
absorption
A fluid that is circulated at absorb heat from a conditioned area is called a _______ refrigerant
secondary
A cooling system that uses a loop of chilled water to provide cooling to a conditioned area is a _____ water system
chilled water system
A system in which the refrigerant is fed into the evaporator at the same rate it evaporates is a direct _______ system
direct expansion system
An all inclusive system is called a _____ central air conditioning system
unitary
A system mounted on a concrete pad adjacent to the building is an _____ air-conditoning unit
outdoor
A system in which the condensing unit is located away from the evaporator is a ____ system
split
A system in which the components are purchased separately and assembled on site is a ____-erected air-conditioning system
field erected air conditioning system
Uses drafts from fans to aid in evaporating a water sit on and around the refrigerant-carrying tubes is an ________ condenser
evaporative
A cooling system that uses a loop of chilled water instead of a forced air to provide cooling is a _____ system
chiller
Fluid that is circulated to absorb heat from a conditioned area is a _______ refrigerant
secondary
Absorbs heat from the secondary refrigerant and rejects heat from the system
primary refrigerant
Component into which refrigerant is fed at the same rate that it evaporates Is a _____ expansion evaporator
direct expansion
A auxiliary component used to remove noncondesables is a _____ unit
purge
Type of chiller used primarily for commercial and industrial process cooling is a ____-pressure chiller
high pressure chiller
Why is water commonly used as a secondary refrigerant in chillers designed for comfort cooling?
cheap to use and non toxic
What function does primary refrigerant in a chiller system serve?
absorbs heat from secondary refrigerant
What is a purge unit?
removes non condensables
What purposes do inlet guide vanes serve in a centrifugal compressor?
control amount of refrigerant entering compressor
How does an evaporative condenser function?
uses drafts from fans to evaporate spray
