Describe the operation of a compressor.
When the piston moves down in the cylinder, it creates a low- pressure condition that allows refrigerant from the low- side tubing to be pushed into the cylinder through the intake valve. After reaching bottom dead center, the piston begins to move upward
Name 5 types of compressors ?
reciprocating , rotary , scroll , screw and centrifugal.
A compressor can compress a liquid. T or F
false
What would be considered a higher - than - normal temperature for a discharge gas line on a reciprocating compressoor ?
250 degrees F
What compressor type uses pistons to compress the gas ?
reciprocating
Which compressor type uses tapered, machined gear components to trap the gas for compression ?
screw
Which style of compressor uses belts to turn the compressor ?
open drive
What would be done to increase the compressor speed on the belt - driven compressor ?
increase drive pulley size
Describe the reciprocating compressor piston, rod, crankshaft, valves, valve plate, head, shaft seal, internal motor overload device , pilot-duty motor overload device, and coupling.
Piston : The device that moves up and down in the cylinder compressing the refrigerant vapor.
Rod ; The connector between the rotating crankshaft and the piston. the mechanism that converts the rotary motion of the shaft to the reciprocating motion of the
Name 2 things in the design of a reciprocating compressor that control the efficiency of the compressor .
valves and clearance volume
At what speed in rpm does a hermetic compressor normally turn ?
3450
What effect does a slight amount of liquid refrigerant have on a compressor over a long period of time ?
Dilutes the oil and causes wear on any moving parts that are in contact with each other.
What lubricates the refrigeration compressor ?
oil
What can the service technician do to keep the refrigeration system operating at peak efficiency ?
Keep the had pressure and the suction pressure with in the design parameters.
List the main advantage that a discus compressor's valve plate design has over a conventional piston- type compressor.
The discus valve design allows for a closer tolerance the compressor's cylinder at the top dead center. This gives the compressor less clearance volume and thus better efficiency. The discus valve design also has a larger bore and allows more refrigerant
Briefly describe how the scroll compressor compresses refrigerant gas.
Scroll compressor operation is relatively simple. Two spiral- shaped scrolls fit inside one another. The two mating parts are often referred to as involute spirals. One of the spiral - shaped parts stays stationary while the other orbits around the statio
List 4 main advantages a scroll compressor has over a conventional piston- type compressor.
1. suction and discharge gases are separated, reducing heat- transfer losses.
2. no volumetric losses occur through reexpansion as with piston-type compressors
3. The scroll compressor has no valves, so there are no valve losses
4. scroll compressors have
What are 2 main reasons why a compressor should have modulating capacity control ?
1. tighter capacity control
2. reduced humidity levels
Briefly describe how the digital capacity control for a scroll compressor works.
If the mating scroll members of a compressor are separated axially, no refrigerant gas will be compressed and only 10 % power usage will be realized. If axial separation of the mating scrolls can be controlled by varying the amount of time they are separa
list 3 main advantages of having digital capacity control on a scroll compressor.
1. very good efficiencies at full- and part - load operations.
2. less compressor cycling for longer lives
3. ability to hold a precise temperature and humidity level
Explain how a compressor can be oil free.
The motor shaft and impellers are the only moving parts in this compressor. The shaft has magnetically levitated bearings for frictionless operation. The magnetic bearings and bearing sensors are composed of both permanent magnets and electromagnets. They