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Gas Compressor And Process Of Compression

A gas compressor is a device in which work is done on the gas to raise its pressure, with an appreciable increase in its density. The compression of  gases in an important process in many plants, refrigeration plants, and industrial plants. Industrial uses occur in connection with compressed air motors for tools, air brakes for vehicles, servo - mechanisms, metallurgical and chemical processes, conveying of  materials through ducts , transporting of natural gas, and production of bottled gases.




Compressors can be 

a)  A positive displacement machines like reciprocating compressors Root's blower and vane -sealed machines.

b)  Turbine type like centrifugal and axial flow compressors.  

 

Process Of Compression :

A Gas compression process may be either adiabatic or involving heat transfer, depending upon the purpose for which the gas is compressed. If the compressed gas is to be used promptly in a engine or in a combustion process, adiabatic compression is so desirable so as to obtain maximum energy in the gas at the end of compression. In many applications , however the gas is not used promptly but is stored in a tank or receiver for use later when needed. The gas in the tank transfer heat to the surroundings so that when finally used it is at room temperature. In such cases, the objective of  the compression and storage process is simply to increase the pressure of the gas without change of temperature. If the gas is cooled during compression, the work required will be less than for adiabatic compression. Another advantage of cooling is the reduction in volume of gas and less pipe friction losses. Since cooling during the compression process is not very effective , after - coolers are often used to cool the gas leaving the compressor. 

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