Refrigeration & Equipment Engineering

Unit 3 - Parts of refrigeration systems

3.1.2.3.1.Advantages and disadvantages of Centrifugal Compressors

Advantages

• Since the centrifugal compressors have no valves, pistons, cylinders, connecting rod, etc., therefore the working life of these compressors is more as compared to Reciprocating compressors.
• These compressors operate with little or no vibration as there are no unbalanced masses.
• The operation of centrifugal compressors is quiet and calm.
• The centrifugal compressors run at high speeds (3000 r.p.m. and above), therefore these can be directly connected to electric motors or steam turbines.
• Because of the high speed, these compressors can handle large volume of vapour refrigerant, as compared to reciprocating compressors.
• The centrifugal compressors are especially adapted for systems ranging from 50 to 5000 tonnes. They are also used for temperature ranges between - 90°C and + 10°C.
• The efficiency of these compressors is considerably high.
• The large sizes centrifugal compressors require less floor area as compared to reciprocating compressors.

Disadvantages

• The main disadvantage in centrifugal compressors is *surging. It occurs when the refrigeration load decreases to below 35 percent of the rated capacity and causes severe stress conditions in the compressor.
• The increase in pressure per stage is less as compared to reciprocating compressors.
• The centrifugal compressors are practical below 50 tonnes capacity load.
• The refrigerants used with these compressors should have high specific volume.