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Nisarg AminFolgen

4. Jul 2016•0 gefällt mir•4,786 views

4. Jul 2016•0 gefällt mir•4,786 views

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Engineering applications of thermodynamics

Nisarg AminFolgen

- 1. Prepared By:- Nisarg Amin Topic : Engineering Applications Of Thermodynamics
- 2. Basic component of steam power cycle: 1.Steam boiler : convert water in to steam 2.Steam turbine : convert kinetic energy of steam in to mechanical energy 3.Condenser : heat transfer device 4.Feed pump : increase the preasure of condansate steam.
- 3. Rankine cyclcle: Process 2-3 in boiler : heat supplied (Qi)=(h3-h2) (since work done is zero) Process 3-4 in turbine: turbine work (Wr)=(h3-h4) (since heat transfer is zero) Process 4-1 in condenser : heat rejected to cooling water,(Qr)=(h4-h1) (since work done is zero) Process 1-2 in feed pump:pump work (Wp)=(h2-h1) (since heat transfer is zero)
- 4. Flow diagram of rankine cycle
- 5. P-V ,T-S ,and h-s diagram of rankine cycle
- 6. Thermal efficiency of rankine cycle Efficiency(ή)=shaft work/heat supplied =[(h3-h4)-(h2-h1)]/(h3-h2) =[(h3-h4)-(h2-h1)]/[(h3-h1)-(h2-h1)] if pump work is neglected than, Efficiency(ή)=(h3-h4)/(h3-h4) Steam rate(S.R):=3600/shaft speed
- 7. Flow diagram of reheat cycle
- 8. T-s and h-s diagram of reheat cycle
- 9. Analysis of reheat cycle The thermal efficiency of reheat cycle is given by, Efficiency(ή)=shaft work/heat supplied eqn-1………. shaft speed (Ws)=(Wt for L.P. +Wt for H.P.)-Wp =(h3-h4)+(h5-h6)-(h2-h1) Heat supplied(Qi)=heat supplied in boiler +heat supplied in reheater =(h3-h2)+(h5-h4) put the value of Ws and Qi in eqn-1….than we get Efficiency(ή)=[(h3-h4)+(h5-h6)-(h2-h1)]/[(h3-h2)+(h5-h4) ]
- 10. Advantages of reheat cycle Improves thermal efficiency the plant since the additional heat is supplied at higher mean temperature. It increases the network output of the turbine. It reduces the steam rate per KWh. It improves the condition of the steam at exhaust of the L.P. turbine so that tendency of blade erosion caused by the liquid particles in the L.P. turbine is reduced. The desirable maximum moisture is steam is considered to be about 10 to 12%.
- 11. Disadvantages of reheat cycle To increase the cost and size of plant due to inclusion of reheater and its long piping. Increase the size of condenser based on unit mass flow of steam due to improved quality of steam of exhaust from L.P. turbine.
- 12. Flow diagram of regenration cylce
- 13. T-s diagram analysis of regeneration cycle It is obvious that the efficiency of regenerative cycle will more than rankine cycle because of the increased mean effective temperature during heat addition process , while the mean temperature of heat rejection process remain same,
- 14. Advantages of regeneration cycle It increases the thermal efficiency of the plant. The temperature stresses in the boiler are reduced due to decreased range of working temperatures.
- 15. Disadvantages of regeneration cycle Steam rate increases due to reduced work done per kg of steam flow from boiler . Therefore ,for a given capacity of the power plant output the boiler size increases. Though the heat rejected in the condenser reduces for unit flow of steam , however , the size of condenser almost remains the same for a given capacity of power plant. The cost of the plant increases.
- 16. Mollier diagrams