COMPRESSORS UNIT 23 EXAM 1 QUESTIONS WITH COMPLETE SOLUTIONS
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Module
COMPRESSORS UNIT 23
Institution
COMPRESSORS UNIT 23
COMPRESSORS UNIT 23 EXAM 1 QUESTIONS WITH COMPLETE SOLUTIONS
Purpose of Economizer - Answer-Reduces flash gas by having a 2 stage pressure drop through float section
Capacity control of centrifugal compressors - Answer-Speed control
Butterfly damper
Variable inlet vanes
Compression factor...
COMPRESSORS UNIT 23 EXAM 1
QUESTIONS WITH COMPLETE
SOLUTIONS
Purpose of Economizer - Answer-Reduces flash gas by having a 2 stage pressure drop
through float section
Capacity control of centrifugal compressors - Answer-Speed control
Butterfly damper
Variable inlet vanes
Compression factors that affect efficiency - Answer-piston/compressor displacement
suction/discharge valves
number of cylinders
clearance pocket (size)
Speed
Suction/discharge pressures
Types of refrigerant used
capacity control method
Positive displacement compressors squeeze a contained gas. The method is to push
the ___ into spaces that become progressively _______. As the gas Molecules are
pushed in on themselves the gas pressure _____. - Answer-gas, smaller, rises
Types of positive displacement compressors are - Answer-Screw compressors
Reciprocating compressors
Scroll compressors
Rotary compressors
Dynamic compressor works to build up molecular velocities and converts this _____ to
static pressure. Most dynamic compressors use __________ impellers to add energy to
a gas. - Answer-energy, centrifugal
Speed
Hermatic compressors
Semi-hermatic compressors
open belt drives
open direct drive - Answer-Synchronous Actual
Formula for calculating compressor speed - Answer-motor speed x motor pulley dia. /
compressor fly wheel dia.
Formula for calculating motor pulley dia. - Answer-compressor speed x compressor
flywheel dia. / motor speed
Compression ratio = - Answer-how hard the compressor works
refrigerant properties are different from refrigerant to refrigerant and will ______ the
operation of the compressor - Answer-impact
Compressor terminology
Saturated suction temp
saturated discharge temp
cubic feet per min
season energy efficiency rating
energy efficiency rating
co-efficient of performance
seasonal performance factor - Answer-SST
SDT
ft3/min
SEER
EER
COP
SPF
compressor specifications for max discharge temperature - Answer-225 to 275F, the
temperature oil starts to break down
compressor specifications for max suction temperature (high temp application) -
Answer-65 to 95F
compressor specifications for minimum suction superheat - Answer-20F, by the time it
gets to compressor inlet
compressor specifications for net positive oil pressure - Answer-30 to 40 psig (min. 10
psig)
Flooding - Answer-Liquid refrigerant returning to the compressor during the running
cycle
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