Introduction:
The series will cover refrigeration and air conditioning compressors, focusing on functions, operations, lubrication, compression ratios, and types of compressors.
The compressor is described as the heart of the refrigeration system, pumping refrigerant vapor and raising its pressure and temperature.
Compressor Function:
The compressor increases the refrigerant pressure from 69 psi to 278 psi and raises the vapor temperature.
The refrigerant vapor is cooled down to its saturation temperature in the condenser, where it condenses and subcools before being sent to the metering device.
Reciprocating Compressors:
Reciprocating compressors are the most common type in refrigeration systems.
The compressor's motor and crankshaft create a circular motion, converted into an up-and-down motion of the pistons.
On the intake stroke, the piston pulls down, the pressure drops, and vapor enters the cylinder.
Compression Process:
During compression, the piston rises, increasing pressure, which opens the discharge valve.
Once fully compressed, the vapor leaves the compressor toward the condenser.
Reciprocating compressors have an inherent inefficiency due to clearance volume, causing some discharge gas to remain in the cylinder, leading to re-expansion and recompression during the next cycle.
Compressor Cycle Review:
The compressor cycle includes three stages: suction, compression, and discharge, which continuously repeat.
The intake valve opens, closes, the piston travels upwards, the discharge valve opens, and the cycle repeats.
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