Thermodynamics for gas turbine cycles 1of2

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Thermodynamics for gas turbine cycles 1of2

  1. 1. Introduction to Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools A  Cycle  Innova-ons  Tutorial  Session   by Pavlos  K.  Zachos  -­‐  Luis  Sanchez  de  Leon Department  of  Power  &  Propulsion Cranfield  University,  UK ASME Turbo Expo 2013 San Antonio, US 1
  2. 2. CRANFIELD UNIVERSITY DEPARTMENT OF POWER & PROPULSION These slides have been prepared by Cranfield University for the personal use of tutorial attendees. Accordingly, they may not be communicated to a third party without the express permission of the author(s). The slides are intended to support the tutorial in which they are to be presented. However the content may be more comprehensive than the presentations they are supporting. Some of the data contained in the notes/slides may have been obtained from public literature. However, in such cases, the corresponding manufacturers or originators are in no way responsible for the accuracy of such material. All the information provided has been judged in good faith as appropriate for the course. However, Cranfield University accepts no liability resulting from the use of such information. Disclaimer 2
  3. 3. Who we are... Pavlos K. Zachos Lecturer in Aerothermal Performance of Turbomachinery Department of Power & Propulsion Cranfield University, UK p.zachos@cranfield.ac.uk Luis Sanchez de Leon Doctoral Researcher in Advanced Cycle Performance Department of Power & Propulsion Cranfield University, UK l.sanchezdeleon@cranfield.ac.uk Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 3
  4. 4. PART I - Thermodynamics in our every day life. Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 4
  5. 5. PART II - A little bit of modelling. Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 5
  6. 6. PART III - A whole lot of modelling. Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 6
  7. 7. Why do you care ? Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 7
  8. 8. The science. The people. The product. Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 8
  9. 9. Thermo dynamics θέρμη (therme) heat δυναμική power = theory of relationship between heat and mechanical energy Aeolipile (or Hero engine) Hero of Alexandria 1st century AD [source: Encyclopedia Britannica] 9
  10. 10. source: Wikipedia Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 10
  11. 11. 1650 Otto von Guericke invents the vacuum pump 1656 Boyle & Hooke notice a correlation between pressure, temperature and volume 18501750 1824 Carnot correlates heat , power, energy & engine efficiency Rankine - Clausius - Lord Kelvin 1st & 2nd Laws of Thermodynamics 1750 Savery builds the first steam piston engine to be later improved by Watt Father of Thermodynamics equation of state Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 11
  12. 12. Entropy, s Temperature,T 1 2 34 Entropy, s Temperature,T 1 2 3 4 Entropy, s Temperature,T 1 2 3 4 v = const. v = const. P = const. v = const. Entropy, s Temperature,T 1 2 3 4 P = const. P = const. Carnot cycle Ideal Otto cycle Ideal Diesel cycle Ideal Brayton cycleThermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 12
  13. 13. 13
  14. 14. Why do you care ? EAT. BREATH. TRAVEL. Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 14
  15. 15. Case study: London to New York 5,526 km 100 days in 1866 by sailing ship 15 days in 1910 by early steam ships 3 days in 1960 by the fastest steam ship < 8 hrs today by plane !! Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 15
  16. 16. = £475 per kg [source: http://www.bullionbypost.co.uk on 21.5.2013] = Courtesy of Rolls-Royce per kg Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 16
  17. 17. aerodynamics materials fuels emissions mechanical integrity market research & logistics system integration cycle thermodynamics controls 17
  18. 18. Entropy, s Temperature,T 1 2 3 4 P = const. P = const. George Brayton 1830 - 1892 Sir Frank Whittle 1907 - 1996 Dr Hans von Ohain 1911 - 1998 Courtesy of Rolls-Royce Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 18
  19. 19. Here’s to the crazy ones. The misfits. The rebels. The troublemakers. The ones who see things differently. They are not fond of rules. And they have no respect for the status quo. You can praise them, disagree with them, quote, disbelieve them, glorify or vilify them. About the only thing you can’t do... Apple advertising campaign September 1997 19
  20. 20. ...is ignore them... 20
  21. 21. ...because they change things 21
  22. 22. ...and also the way WE see things... 22
  23. 23. Let’s talk about today... Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 23
  24. 24. 6 Trillion kg CO2 source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 24
  25. 25. 20,000 kg CO2 per year and person 4,500 kg CO2 per year and person source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 25
  26. 26. 26
  27. 27. 27
  28. 28. 28
  29. 29. 450 ppm source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 29
  30. 30. 10% less rainfall source: ClimateCrisis.netThermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 30
  31. 31. Dust storm approaching Stratford,TEXAS - April 1935source: http://www.weru.ksu.edu 31
  32. 32. aerodynamics materials fuels emissions mechanical integrity market research & logistics system integration cycle thermodynamics controls 32
  33. 33. Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 33
  34. 34. PART II 34
  35. 35. Families of thermodynamic cycles Power cycles Refrigeration cycles Gas cycles Vapor cycles Closed cycles Open cycles Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 35
  36. 36. Families of thermodynamic cycles Power cycles Refrigeration cycles Gas cycles Vapor cycles Closed cycles Open cycles Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 36
  37. 37. Basic considerations in the analysis of power cycles 1. Study the ideal cycle first No friction No heat losses Quasi-equilibrium compressions & expansions 2. Neglect kinetic and potential energies 3. Use P-v or T-s diagrams Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 37
  38. 38. • Air as working fluid • Ideal gas Air standard assumptions Equation of State: PV = RT Cp Cv = γ R = Cp - Cv • Semi-perfect gas Cp / Cv functions of Temperature γ= 1.33 - Turbines γ= 1.40 - Compressors Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 38
  39. 39. Internal Energy = The total energy contained by a thermodynamic system Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 39
  40. 40. Internal Energy = u(T) Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 40
  41. 41. u(T) + pV = Enthalpy Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 41
  42. 42. u(T) + pV = Enthalpy u(T) + RT = Enthalpy = h(T) Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 42
  43. 43. Specific Heat Capacity at ConstantVolume Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 43
  44. 44. Specific Heat Capacity at ConstantVolume = Cv Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 44
  45. 45. Specific Heat Capacity at ConstantVolume = Cv = du dT Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 45
  46. 46. Specific Heat Capacity at Constant Pressure Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 46
  47. 47. Specific Heat Capacity at Constant Pressure = Cp Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 47
  48. 48. Specific Heat Capacity at Constant Pressure = Cp = dh dT Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 48
  49. 49. Ideal Gas Model PV = RT Internal Energy = u(T) = Cv T Enthalpy = u(T) + RT = h(T) = Cp T Cp Cv =γ γ= 1.33 - Turbines γ= 1.40 - Compressors Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 49
  50. 50. Wilcock R. C.,Young J. B., and Horlock J. H., 2002,“Gas properties as a limit to gas turbine performance.” Kyprianidis K., SethiV., Ogaji S. O., PILIDIS P., Singh R., and KALFAS A. I., 2009, “Thermo-Fluid Modelling for Gas Turbines-Part I:Theoretical Foundation and Uncertainty Analysis.” Kyprianidis K., SethiV., Ogaji S. O., PILIDIS P., Singh R., and KALFAS A. I., 2009, “Thermo-Fluid Modelling for Gas Turbines-Part II: Impact on Performance Calculations and Emissions Predictions at Aircraft System Level.” Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 50
  51. 51. Entropy, s Temperature,T 1 2 3 4 P2 = const. P1 = const. heat in heat out work in maximum cycle pressure limited by compressor technology maximum cycletemperaturelimited by turbinetechnology work out Useful work (Net) Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 51
  52. 52. Entropy, s Temperature,T 1 2 3 4 P2 = const. P1 = const. heat in heat out work in work out Compressor Turbine Combustion chamber Ideal Brayton cycle processes: 1-2: Isentropic compression 2-3: Constant pressure heat addition 3-4: Isentropic expansion 4-1: Constant pressure heat rejection Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 52
  53. 53. Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 53
  54. 54. win Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 54
  55. 55. win qin + Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 55
  56. 56. win qin + wout - Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 56
  57. 57. win qin + wout - qout - Inlet Enthalpy Outlet Enthalpy (qin - qout) + (win - wout) = 0 = -wnet wnet = qin - qout Steady-flow process energy balance on a unit-mass basis: -= 57
  58. 58. wnet = qin - qout qin = h3 - h2 = cp (T3 - T2) qout = h4 - h1 = cp (T4 - T1) Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 58
  59. 59. Entropy, s Temperature,T 1 2 3 4 P2 = const. P1 = const. heat in heat out work in work out Compressor Turbine Combustion chamber Fresh air Fuel Exhaust gases work out wnet = qin - qout qin = h3 - h2 = cp (T3 - T2) qout = h4 - h1 = cp (T4 - T1) ηthermal = wnet qin = 1- qout qin using... T2 T1 = P2 P1 ( ) γ-1/γ = P3 P4 ( ) γ-1/γ = T3 T4 ηthermal = 1- 1 P2 P1 γ-1/γ Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 59
  60. 60. Entropy, s Temperature,T 1 2 3 4 P2 = const. P1 = const. heat in heat out work in work out Compressor Turbine Combustion chamber Fresh air Fuel Exhaust gases work out ηthermal = 1- 1 P2 P1 γ-1/γ ηthermal Pressure ratio Is this right ? Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 60
  61. 61. Entropy, s Temperature,T 1 2s 4s2a in reality... - no compression/expansion is isentropic & - some pressure loss is inevitable 4a 3 ηcompr ηturb = = h2s - h1 h2a - h1 h3 - h4a h3 - h4s Component isentropic efficiencies: note for preliminary cycle modelling component efficiencies can be guessed or estimated Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 61
  62. 62. Case  study  #1: Effect  of  compressor  efficiency  on  cycle  performance Compressor Turbine Combustion chamber - Standard air assumptions - Standard ISA conditions: 288.15K @ 1 bar - Constant ηt,is - T3 = 1600K - Combustion efficiency=0.98 - Account for cooling flows isentropic Isentropic 0.9 0.85 0.8 Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 62
  63. 63. 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1 3 5 7 9 11 13 15 OVERALL PRESSURE RATIO ISENTROPICEFFICIENCY POLYTROPIC EFFICIENCY = 0.90 0.85 0.8 Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 63
  64. 64. Case  study  #2: Effect  of  Turbine  Entry  Temperature  on  cycle  performance Compressor Turbine Combustion chamber - Standard air assumptions - Standard ISA conditions: 288.15K @ 1 bar - Constant ηt,is - Combustion efficiency=0.98 - Account for cooling flows Assuming a value for the polytropic efficiency of our compressor a new isentropic efficiency is calculated for every pressure ratio based on: TET = 1000 K 1200 K 1400 K 1600 K 1800 K Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 64
  65. 65. Cycle  design  in  a  gas  turbine  performance  solver Use  of  “BRICKS” Compressor Turbine Combustion chamber Thrust per unit flow Intake Fresh air ALTITUDE MACH No. Rel. Humidity PRESSURE RECOVERY FACTOR PRESSURE RATIO POLYTROPIC EFFICIENCY BLEED FLOWS COMBUSTION EFFICIENCY PRESSURE LOSS TURBINE ENTRY TEMPERATURE (TET) ISENTROPIC EFFICIENCY COOLING FLOWS Nozzle Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 65
  66. 66. Cycle  design  in  a  gas  turbine  performance  solver Use  of  “BRICKS” Compressor Turbine Combustion chamber Intake Fresh air ALTITUDE MACH No. Rel. Humidity PRESSURE RECOVERY FACTOR PRESSURE RATIO POLYTROPIC EFFICIENCY BLEED FLOWS COMBUSTION EFFICIENCY PRESSURE LOSS TURBINE ENTRY TEMPERATURE (TET) ISENTROPIC EFFICIENCY COOLING FLOWS Output Power per unit flow Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 66
  67. 67. Case  study  #3: Single  spool  gas  generator  design  space  exploraIon Compressor Turbine Combustion chamber Intake Fresh air ALTITUDE MACH No. Rel. Humidity PRESSURE RECOVERY FACTOR PRESSURE RATIO POLYTROPIC EFFICIENCY BLEED FLOWS COMBUSTION EFFICIENCY PRESSURE LOSS TURBINE ENTRY TEMPERATURE (TET) ISENTROPIC EFFICIENCY COOLING FLOWS Output Power per unit flow 0.9 0.98 5% 0.91 Specific Fuel Consumption = Fuel flow [kg/s] definitions or SFC Specific Power = Net Output [J/s] Net Output [J/s] Mass flow [kg/s] Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 67
  68. 68. PR = 3 PR = 6 PR = 15TET = 1000 K TET = 1200 K TET = 1400 K TET = 1600 K Large size High weight Small size Low weight Low technology High technology Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 68
  69. 69. Compressor Turbine Combustion chamber Intake Fresh air ALTITUDE MACH No. Rel. Humidity PRESSURE RECOVERY FACTOR PRESSURE RATIO POLYTROPIC EFFICIENCY BLEED FLOWS COMBUSTION EFFICIENCY PRESSURE LOSS TURBINE ENTRY TEMPERATURE (TET) ISENTROPIC EFFICIENCY COOLING FLOWS Thrust per unit flow Nozzle Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 69
  70. 70. High Pressure Compressor Combustion chamber Low Pressure Compressor Low Pressure Turbine High Pressure Turbine COMING UP NEXT... Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 70
  71. 71. High Pressure Compressor Combustion chamber Low Pressure Compressor Low Pressure Turbine High Pressure Turbine COMING UP NEXT... Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 71
  72. 72. High Pressure Compressor Combustion chamber Low Pressure Compressor Low Pressure Turbine High Pressure Turbine COMING UP NEXT... Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 72
  73. 73. High Pressure Compressor Combustion chamber Low Pressure Compressor Low Pressure Turbine High Pressure Turbine Combustion chamber COMING UP NEXT... Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 73
  74. 74. High Pressure Compressor Combustion chamber Low Pressure Compressor Low Pressure Turbine High Pressure Turbine Combustion chamber COMING UP NEXT... Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 74
  75. 75. Related textbooks Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 75
  76. 76. Related textbooks Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools ASME Turbo Expo San Antonio,Texas, 6th June 2013 76
  77. 77. Introduction to Thermodynamics for Gas Turbine Cycles & Cycle Simulation Tools further  info,  compliments  &  complaints  to  be  addressed  to: p.zachos@cranfield.ac.uk   ASME Turbo Expo 2013 San Antonio, US 77

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