Book 2: 4-18 - "Refrigeration Compressors" Flashcards
The male (driving) rotor in the helical screw compressor usually has _____ helical lobes along the length of the rotor.
Select one:
A. Two
B. Five
C. Four
D. Six
E. Three
C. Four
The rotary design of refrigeration compressors includes all of the following except:
Select one:
A. Helical rotor
B. Stationary single-blade
C. Helical screw
D. Piston
E. Rotating vane
D. Piston
One of the functions of the compressor in a refrigeration system is to raise the _____ pressure and temperature.
Select one:
A. High-temperature, low-pressure liquids
B. Low-temperature, high-pressure vapours
C. Low-temperature, low-pressure liquids
D. Low-temperature, low-pressure vapours
E. High-temperature, low-pressure vapours
D. Low-temperature, low-pressure vapours
The theoretical mass of refrigerant moved in a compressor is 8.65 kg/min (19 lb/min). If the compressor has a volumetric efficiency of 70%, what is the actual mass moved?
Select one:
A. 9.84 kg/min (21.7 lb/min)
B. 6.21 kg/h (13.7 lb/h)
C. 6.32 kg/min (13.9 lb/min)
D. 6.06 kg/min (13.3 lb/min)
E. 12.35 kg/h (27.19 lb/h)
D. 6.06 kg/min (13.3 lb/min)
To prevent damage to the reciprocating compressor by the _____ compressors are often fitted with a safety head.
Select one:
A. Hydraulic pressure resulting from trapped vapour at the end of the compression stroke
B. Hydraulic pressure resulting from trapped liquid at the end of the compression stroke
C. Hydraulic temperature resulting from trapped vaopur at the end of the compression stroke
D. Hydraulic pressure resulting from trapped liquid at the end of the intake stroke
E. Hydraulic temperature resulting from trapped liquid at the end of the compression stroke
B. Hydraulic pressure resulting from trapped liquid at the end of the compression stroke
The main parts of a refrigerant reciprocating compressor include all except the:
Select one:
A. Compressor body
B. Rotor
C. Pistons and connecting rods
D. Safety head
E. Suction and discharge valves
B. Rotor
In terms of energy transformation in the centrifugal compressor the kinetic energy of the _____ is transformed into potential energy in the high-pressure, low-velocity compressed vapour.
Select one:
A. Low-pressure, high-velocity liquid
B. High-pressure, high-velocity vapour
C. Low-pressure, high-velocity vapour
D. Low-pressure, low-velocity liquid
E. Low-pressure, low-velocity vapour
C. Low-pressure, high-velocity vapour
A two cylinder compressor has a 90 mm bore and a stroke of 115 mm. Calculate the volume compressed per hour if the compressor operates at 400 r/min.
Select one:
A. 35.12 m³/h
B. 79.62 m³/h
C. 79.62 m³/min
D. 19.91 m³/h
E. 17.56 m³/min
A. 35.12 m³/h
The main parts of a refrigerant reciprocating compressor include all except the:
Select one:
A. Suction and discharge valves
B. Blades
C. Pistons and connecting rods
D. Compressor body
E. Compressor bearings
B. Blades
One of the functions of the compressor in a refrigeration system is to draw the:
Select one:
A. Low-temperature, high-pressure vapour from the evaporator
B. Low-temperature, low-pressure liquid from the evaporator
C. High-temperature, low-pressure vapour from the evaporator
D. Low-temperature, low-pressure vapour from the condenser
E. Low-temperature, low-pressure vapour from the evaporator
E. Low-temperature, low-pressure vapour from the evaporator
Packing gland seals are made of _____.
Select one:
A. Metallic bellows soldered at one end to a ring bearing against a seal ring mounted on the shaft
B. A diaphragm soldered to a seal nose held between compressor body and cover plate
C. Semi-metallic material impregnated with graphite
D. A mating ring and a sealing ring
E. Metallic bellows soldered at one end to a ring bearing against a shoulder on the shaft
C. Semi-metallic material impregnated with graphite
A bellows seal consists essentially of a metallic bellows soldered at one end to a ring (seal nose) which bears either against a shoulder on the shaft or against a seal ring mounted on the shaft and the other end is:
Select one:
A. A diaphragm soldered to a seal nose held between compressor body and cover plate
B. A sealing ring
C. A mating ring
D. Fastened to a flange which is tightly held against the housing by a cover plate
E. A metallic bellows soldered at one end to the shaft
D. Fastened to a flange which is tightly held against the housing by a cover plate
Which compressor type requires the use of a shaft seal?
Select one:
A. Closed
B. Open type
C. Semi-hermetic
D. Hermetic
E. Serviceable
B. Open type
The female (driven) rotor in the helical screw compressor usually has _____ helical grooves or flutes along the length of the rotor.
Select one:
A. Two
B. Four
C. Six
D. Three
E. Five
C. Six
One of the main classifications of refrigeration compressors is the _____ compressor.
Select one:
A. Reciprocating
B. Vane
C. Axial
D. Piston
E. Screw
A. Reciprocating
