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Power Engineering and Refrigeration, , Moving blades are mounted on the rotor, while fixed blades are fixed on stator or casing,, The blades are aero-foil shape for efficient, working. Air flows through the annulus ring, between the rotor and the stator over the blades,, parallel to the axis of the compressor., , As the rotor rotates, air in the blades passage, accelerate due to which velocity and pressure, increases, The air then passes through fixed blade, passages of diffuser shape in which velocity of air, decreases and pressure increases, pressure rise in, each stage is of the order 12 to 15% and the, number of stages used vary from 5 to 14. It can, handle air up to 30000 m3/min. It is mainly used in, gas turbine plants., , 3.5, , , , ar, , Air Compressors,, , casing, , Fixed blades Moving blades, , , , . 3.18 : Axial flow compressor, , , , [3.16 COMPARISON BETWEEN RECIPROCATING AND ROTARY COMPRESSOR, , , , , , , , Reciprocating Compressor, , Rotary Compressor, , , , 1. Compression of air takes place with the help of, piston and cylinder arrangement with reciprocating, motion of piston., , 1 Compression of air takes place due to rotary, motion of blades., , , , Delivery of air is intermittent., , 2. Delivery of airs continuous, , , , Delivery pressure is high, ie. Pressure ratio is high., , 3._Delivery pressure is low, ie. Pressure ratio is low., , , , Flow rate of air is low., , “4. Flow rate of airs high., , , , Speed of compressor is low because of unbalanced, forces., , 5. Speed of compressor is high because of perfect, balancing,, , , , 6 Reciprocating air compressor has more number of, moving parts. it needs proper lubrication and more, maintenance, , 6. Rotary air compressor has less number of moving, parts, therefore less maintenance is required,, , , , 7. Due to low speed of rotation it cannot be directly, coupled to prime mover but it requires reduction of, speed, , 7. Rotay air compressor can be directly coupled to, prime mover., , , , 8 Are used where small quantity of air at high pressure, is required, , & Are used where large quantity of air at lower, pressure is required., , , , ‘9. Maximum delivery pressure may be as high as 1,000, bar., , 9. Maximum delivery pressure is 10 bar only., , , , 10. Maximum free air discharge is as high as 300, , m/min., , 10. Maximum free air discharge is as high as 3,000, , m/min., , , , 11. Size of compressor is large for given discharge., , LL. Size of compressor is small for the same discharge., , , , 12. Air delivered is less clean, as it comes in contact with, , the lubricating oil, , 12. Air delivered is more clean, as it does nat comes in, , contact with the lubricating oil, , , , 1B Isothermal efficiency is used for all sorts of, calculations., , 14, Due to low speed of rotation it cannot be directly, coupled to prime mover but it requires reduction of, , speed., , , , , , 1B.Isentropic efficiency is used for all sorts of, calculations., , 14. It can be directly coupled to prime mover.