Worksheets12. ACR-104 UNIT 23 END OF UNIT TEST
Total questions: 32
Worksheet time: 22mins
If the compression ratio of a system with a reciprocating compressor decreases, the amount of refrigerant pumped by the compressor ____.
will increase
will decrease
will remain the same
cannot be determined
Most of the heat energy in the suction vapor entering the compressor is ____.
subcooled from the condenser
superheated from the condenser
superheated from the evaporator
subcooled from the evaporator
The temperature of the compressed gas leaving the compressor can best be described as ____.
cold
cool
warm
very warm
The screw compressor is used primarily in ____.
large commercial and industrial systems
residential air conditioning
small commercial refrigeration units
domestic refrigerators
Rotary compressors are used primarily in ____.
large industrial refrigeration and air conditioning systems
residential and light commercial air-conditioning
small commercial refrigeration units
high volume residential refrigeration
The clearance volume of a compressor cylinder is the ____.
amount of refrigerant vapor the compressor cylinder will hold during each stroke
volume by which the compressor is rated
volume of the space between the bottom of the valve plate and the top of the piston at the top of the stroke
total volume of the cylinder when the piston is at the bottom dead-center
The discus valve design is more efficient than a flapper valve design because _____.
it allows a compressor design with less clearance volume
it operates with less spring tension
the amount of expanded vapor in the cylinder is greater
it will not allow liquid refrigerant in the cylinder
Liquid entering the compression chamber of a reciprocating compressor can lead to _____.
damaged valves
damaged piston rings
damaged expansion valves
Both a and b.
Rotary compressors have pistons that rotate inside the cylinders.
True
False
The rotary screw compressor uses an open motor instead of the hermetic design.
True
False
The sight glass on a semihermetic compressor is used to allow light to enter the crankcase to keep the oil warm.
True
False
The shell of a hermetic type reciprocating compressor is generally considered to be on the low pressure side of the system.
True
False
The hermetic reciprocating compressor motor is essentially made of the same materials as an open type compressor motor.
True
False
A bolted together motor-compressor assembly is sometimes referred to as a semihermetic type.
True
False
Mufflers are used in many fully hermetic compressors to muffle compressor pulsation noise.
True
False
The higher the rpm of a compressor, the higher the pumping efficiency.
True
False
Scroll compressors are becoming popular because they can handle liquid floodback without compressor damage.
True
False
The scroll compressor is one type of reciprocating compressor.
True
False
SEER is calculated based on the total amount of cooling (in BTU) the system will provide over the entire season, divided by the total number Watt-Hours it will consume.
True
False
Because a scroll compressor’s has fewer moving parts, it operates much quieter than other compressor designs and technologies.
True
False
Excessive heat and pressure on the oil in a compressor can cause oil to break down and cause the formation of and acid.
The type of compressor that is driven by a belt is the compressor.
open drive
A compressor that has the motor and compressor in one housing that is welded together is called a(n) ____________________ type.
(a)A compressor that has the motor and compressor in a housing that is bolted together is called a(n) type.
semi-hermetic
open
Pistons are connected to the crankshaft using connecting rods and .
washers
bearings
wrist pins
gaskets
When the piston reaches the bottom of its stroke, it is called .
The space at the top of the cylinder when the piston reaches the top of its stroke is called _________.
____________________ is a bimetallic disc that senses compressor discharge temperature and opens at 270°F.
____________________ opens at approximately 400 ± 50 psi differential between high- and low-side pressures for R-22, and at a 500 to 625 psi differential for R-410A.
Internal pressure relief
External pressure relief
Temperature control valve
When is the compressor’s lubrication system fully effective?
When the compressor reaches its full running speed
When the compressor is turned on
When the compressor is turned off
When the compressor is in standby mode
What happens to refrigerant that does not exit when the piston reaches top dead-center?
It escapes through the exhaust valve.
It evaporates and exits through the intake valve.
It condenses and returns to the compressor.
The small amount of gas in the clearance volume will be reexpanded
A decrease in suction pressure will have what effect on a reciprocating compressor.
The compressor will pump less refrigerant
The compressor will pump more refrigerant
