Describe the operation of a compressor
It lifts the low pressure gas from the suction side of the system to the discharge side of the system = vapor pump
Name five types of compressors
Rotary Vane, Scroll, Centrifugal, Reciprocating , Screw
Can a compressor pump liquid?
No = damage will occur
What would be considered a higher than normal discharge temp on a reciprocating compressor?
215 F
Which compressor type uses pistons to compress the gas?
Reciprocating
Which compressor type uses tapered, machine gear components to trap the gas for compression?
Screw
Which style of compressor uses belts to turn the compressor?
Belt Driven
What would be done to increase the compressor speed on a belt driven compressor?
drive size X drive rpm = driven size X driven rpm
Describe The reciprocating compressor piston
the part of the cylinder assembly exposed to the high pressure gas during compression. High pressure gas on top (upstroke) .... Low pressure gas on bottom (downstroke)
Describe The reciprocating compressor connecting rod
Connects the crankshaft to the piston
Describe The reciprocating compressor crankshaft
transmits the circular motion of the rods into a back and forth (reciprocating) motion for the pistons
Describe The reciprocating compressor valves
at the top of the compressor determine in which direction the gas will flow
Describe The reciprocating compressor valve plate
Holds the suction and discharge flapper valves. Located between the head of the compressor and the top of the cylinder wall
Describe The reciprocating compressor head
The component that holds the top of the cylinder and its assembly together
Describe The reciprocating compressor shaft seal
has a rubber surface to keep the refrigerant and the atmosphere separated
Describe The reciprocating compressor internal motor overload device
Protect the motor from overheating, they are embedded into or near the windings.
Describe The reciprocating compressor pilot duty overload device
Pilot duty motor overload device: interrupts the controlled voltage
Describe The reciprocating compressor coupling
obtains the correct shaft alignment
Describe The reciprocating compressor discus valve
allows a closer tolerance inside the compressor cylinder at the top dead center = more efficient because it reduces clearance volume
Name two things in the design of a reciprocating compressor that control its efficiency?
clearance volume and bore size
In what speed in RPM does a hermetic compressor normally turn
1750 rpm and 3450 rpm
What effect does a small amount of liquid have on a compressor over a long period of time?
liquid slugging = oil dilution
What lubricates the refrigeration compressor?
Oil
What can a service technician do to keep the refrigeration system operating at peak efficiency?
Keeping the evaporator and condenser clean will enhance the compressor ratio. Running suction pressure as high as practical ... running discharge pressure as low as practical
What advantage does a discus valve plate have over a conventional piston type compressor
Discus valve allows closer tolerance inside the compressor cylinder at the top dead-center. The closer tolerance provides more efficiency because of less clearance volume. It also has a larger bore and allows more gas through the port within a short perio
Describe how a scroll compressor compresses gas
Two spiral shaped scrolls fit inside one another. These two mating parts are often referred to as involute spirals. One of the spiral shaped parts stays stationary while the other orbits around it.
List four main advantages a scroll compressor has over a conventional piston type compressor
No volumetric losses through gas re expansion. Does not have valve losses that contribute to inefficiencies. No valve noise and very soft gas pulsation noises/vibration. Separation of suction and discharge gases reduce heat transfer loss. Mating scrolls m
What are two main reasons a compressor should have modulating capacity control
reduce power consumption , produce better dehumidification control, and reduce compressor cycling along with small compressor starting currents
How does the digital capacity control for a scroll compressor work
Digital scroll compressor is a disengaging solenoid valve for bypassing discharge gas to the suction side of the compressor. An energized solenoid valve will unload the compressor by axially separation the scrolls making the compressor capacity zero
List three main advantages of digital capacity control on a scroll compressor
Ability to hold a precise temperature and humidity level
- efficient full-load and part load efficiencies
- ability to be 30% more efficient than traditional compressor modulation methods
- less compressor cycling for longer compressor life
- delivery of
How can a compressor be oil free
The cenrifugal compressor is oil free because the rotor and the shaft are the only moving parts, the shaft acts as a rotor for the permanent magnet synchronous motor. The motor shaft has magnetically levitated bearings for frictionless operation.