Centrifugal compressor

This compressor works on the principle of centrifugal action. It finds wide variety of applications in engineering field. It is available in market from low to high capacities.

1. STUDY ON CENTRIFUGAL COMPRESSOR 1 PRASANTH.M M.E THERMAL ENGG

2. 2 CONTENT INTRODUCTION CONSTRUCTION WORKING PRINCIPLE ANALYSIS OF CENTRIFUGAL COMPRESSOR VELOCITY DIAGRAM REFRIGERANT CAPACITY CAPACITY CONTROL PERFORMANCE ASPECTS REFERENCE

3. 3 INTRODUCTION Centrifugal compressors are rotary type of compressors It gives high volume flow rate They are designed for high capacity applications It is available in single stage as well as multistage They are operated in wide range of speed

4. 4 Evaporator temperatures : -100◦C to +10◦C Evaporator pressures : 14 kPa to 700 kPa Discharge pressure : upto 2000 kPa Rotational speeds : 1800 to 90,000 RPM Refrigeration capacity : 300 kW to 30000 kW OPERATING RANGE

5. 5 CONSTRUCTION

6. 6 WORKING PRINCIPLE C ontinuous conversion of angular momentum of refrigerant vapour by a high-speed impeller into static pressure T he refrigerant enters the impeller where it gains momentum and its static pressure also increases T he refrigerant flows into a stationary diffuser where pressure drop is converted into static pressure rise The vapour enters the volute casing where further conversion of velocity into static pressure takes place

7. 7 ANALYSIS OF CENTRIFUGAL COMPRESSORS The energy equation of compressor is given by Neglecting kinetic and potential energy T he heat transfer rate Q is normally negligible, so the work input is given by

8. 8 VELOCITY DIAGRAM

9. 9 The work input to the impeller is given by T he power input to the compressor depends on the blade angle β The blade angle will be less than 90◦ for backward curved blade The blade angle is equal to 90◦ for radial blades The blade angle will be greater than 90◦ for forward curved blade. The tangential velocity is given by

10. 10 REFRIGERANT CAPACITY OF CENTRIFUGAL COMPRESSOR The mass flow rate through a centrifugal compressor is given by

11. 11 CAPACITY CONTROL The capacity of a centrifugal compressor is normally controlled by Adjusting the inlet guide vanes Adjusting the guide vanes of vaned diffusers. V arying the compressor speed using VFD

12. 12 PERFORMANCE ASPECTS PV DIAGRAM

13. 13 CONDENSING TEMPERATURE vs LOAD

14. 14 EVAPORATOR TEMPERATURE vs LOAD

15. 15 CONDENSING TEMPERATURE vs COMPRESSOR POWER

16. 16 SPEED vs REFRIGERATING EFFECT

17. 17 SPEED vs COMPRESSOR WORK

18. 18 REFERENCE www.nptel.com