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HCCI – Diagnostics and Control

HCCI – Diagnostics and Control. Prof. Bengt Johansson Div. of Combustion Engines, Dept. of Heat and Power Engineering,. bengt.johansson@vok.lth.se www.vok.lth.se. Outline. Current engines HCCI in general HCCI in Lund, some results Production. Normal SI engine fuel consumption.

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HCCI – Diagnostics and Control

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  1. HCCI – Diagnostics and Control Prof. Bengt Johansson Div. of Combustion Engines, Dept. of Heat and Power Engineering, bengt.johansson@vok.lth.se www.vok.lth.se

  2. Outline • Current engines • HCCI in general • HCCI in Lund, some results • Production

  3. Normal SI engine fuel consumption

  4. Introduction Lean limit 100% Catalyst Efficiency 99% 98%  0.8 1.0 1.5 2.0 2.5 5.0 SI engine - part load improvement Stoichiometric premixed charge SI engine - Low part load efficiency + Low emissions with 3-way catalyst Lean burn premixed charge SI engine + Reduced pumping work  improved part load efficiency - Increased HC and NOx Stratified charge SI engine - GDI + Removed pumping work  much improved part load efficiency - Large problem with NOx and PM HCCI + Removed pumping work  much improved part load efficiency + Shorter combustion period  improved overall efficiency - Engine control problem 

  5. HCCI vs. GDI and CAI

  6. Diesel Engine (CI) • Large problems with emissions of NOx and PM • High fuel efficiency (low CO2 emission)

  7. HCCI Emissions AutoTechnology Oct. 2002, p 54 HCCI 0,01 USA 2007 * PM 0,00 0,05 0 0,5 NOx

  8. HCCI in Lund

  9. HCCI activities in Lund • Basic engine studies • Laser diagnostics • Combustion modeling - Chemical kinetics • Closed loop combustion control

  10. Experimental facilities – single cylinder engines Scania 2 liter (Volvo 1.6 liter) Volvo/Alvar 0.5 liter VCR Old Hot bulb engine

  11. Multicylinder engines for HCCI control Scania 12 liter 6 cylinder dual fuel Volvo 12 liter 6 cylinder VGT Volvo 3 liter 6 cylinder VVT Saab 1.6 liter 5 cylinder VCR/FTM

  12. Current optical engines

  13. HCCI activities in Lund • Basic engine studies • Laser diagnostics • Combustion modeling - Chemical kinetics • Closed loop combustion control

  14. Volvo TD100 engine

  15. First VCR system

  16. Multifuel capability

  17. Multifuel capability

  18. Low NOx from HCCI mode Gasoline & Diesel fuel 0.05 100% Gas l =3.0 0.045 65% Gas n=1000 rpm 40% Gas 0.04 20% Gas 0% Gas 0.035 0.03 Specific NOx emissions [g/kWh] 0.025 0.02 0.015 0.01 0.005 0 10 15 20 25 Compression Ratio

  19. With Variable Compression Ratio, VCR, the HCCI engine can useANYliquid or gaseous fuel!

  20. Basic engine tests…

  21. The effect of turbulence on HCCI combustion

  22. Turbulence and geometry effects on HCCI Experimental setup Square bowl-in-piston Disc Swirl Ratio=2.8 HS case Swirl Ratio=2.0 LS case

  23. Turbulence and geometry effects on HCCI 4 Disc, LS Head Centre Position Disc, HS Head 3.5 Square, LS Head Square, HS Head 3 2.5 Turbulence [m/s] 2 1.5 1 0.5 0 -50 -40 -30 -20 -10 0 10 20 30 40 50 Crank Angle [CAD] Turbulence

  24. Turbulence and geometry effects on HCCI 8 Disc, LS Head Side Position Disc, HS Head 7 Square, LS Head Square, HS Head 6 5 Turbulence [m/s] 4 3 2 1 0 -50 -40 -30 -20 -10 0 10 20 30 40 50 Crank Angle [CAD] Turbulence Different scale

  25. Turbulence and geometry effects on HCCI 800 Disc, LS Head SOC=-2 CAD Disc, HS Head 700 Square, LS Head Square, HS Head 600 500 Rate of Heat Release [J/CAD] 400 300 200 100 TDC 0 -5 0 5 10 ° Crank Angle [ ATDC] Rate of Heat Release

  26. HCCI activities in Lund • Basic engine studies • Laser diagnostics • Combustion modeling - Chemical kinetics • Closed loop combustion control

  27. The influence of Charge Heterogeneity on the HCCI Combustion Process (?)

  28. Fuel DistributionPrior to Combustion With port-injection With mixing tank

  29. Tracer PLIF after Auto-ignition With port-injection With mixing tank

  30. OH PLIF Imaging With port-injection With mixing tank

  31. High Speed Fuel LIF

  32. Multi YAG-Laser System Ordinary laser t Multiple pulse laser t • Single/Double pulse operation • 4 Pulses:Time separation (0-100ms) • 8 Pulses:Time separation (6-145µs) • Wavelengths:532nm and 266nm • Dye-laser for tuneable operation

  33. High Speed Camera • 8 independent CCD’s, 576x384 pixels 10 ns temporal resolution • Optional image intensifier  UV sensitive 1 µs temporal resolution

  34. Cyl. Volume 1951 cm3 Bore 127 mm Stroke 154 mm Comp. Ratio 16:1 Chamber design Pancake Fuel Ethanol Lambda 3.85 Experimental setup(Scania)

  35. 2 ATDC 2.5 ATDC 3 ATDC 3.5 ATDC 4 ATDC 4.5 ATDC 5 ATDC 5.5 ATDC • Fuel: ethanol • Tracer: 10% acetone • l3.85 • Rc: 16:1 Fuel Tracer PLIF(resolved single-cycle) W16mars_4

  36. Conceptual model of HCCI Assuming homogeneous distributions of P, l, EGR% and RR: Ignition occurs when I reaches a critical value

  37. Conceptual model of HCCI Effect of heterogeneous air/fuel ratio

  38. Ignition Temperature

  39. Turbulence and geometry effects on HCCI +2 +2.5 +3 +3.5 +4 +4.5 +5 +5.5 Suppression of hot and reactive zones Single cycle fuel tracer LIF sequences

  40. HCCI activities in Lund • Basic engine studies • Laser diagnostics • Combustion modeling - Chemical kinetics • Closed loop combustion control

  41. The 6-cylinder HCCI Engine

  42. Closed loop combustion control, CLCC Inlet Conditions (pin,Tin) User Inputs HEATERS PC Status Calculation NI PCI 6054 WaveBook 516 n-heptane i-octane PID Controllers PressureTraces Injector Actuator

  43. Control Parameters 6 x 10 15 Max dp/dCA Max Pressure 10 Cylinder Pressure [Pa] 5 0 -40 -20 0 20 40 60 80 Controlled • CA50 • Net IMEP:s Constraints • Peak pressure • Peak dp/dCA • Net heat release 3000 Heat Release 2000 Heat Release, Q [J] 1000 0 CA50 -1000 -40 -20 0 20 40 60 80 Crank Angle [deg ATDC]

  44. Combustion phasing=combustion duration

  45. Combustion Timing Ignition Diagram 15 10 5 Combustion phasing [CA 50] 0 40 50 60 70 80 90 100 -5 -10 Octane Number S = d(CA50%) / d(Octane Number)

  46. Sensitivity Estimation

  47. Unstable Operation 35 Stable Unstable 30 25 20 CA50 [°ATDC] 15 10 5 0 0 100 200 300 400 Cycle Index @ 3 bar IMEP @ 4.5 bar IMEP Closed loop control switched off

  48. Operating range 280 kW (380 hk) • HCCI Diesel • 21 bar • 280 310 kW

  49. Typical high load cycle 200 2 180 1.8 160 1.6 140 1.4 120 1.2 Cylinder Pressure [bar] Rate of Heat Release [kJ/CAD] 100 1 80 0.8 60 0.6 40 0.4 20 0.2 0 0 -30 -30 -20 -20 -10 -10 0 0 10 10 20 20 30 30 Crank angle [CAD] Load limited by Peak Cylinder Pressure at 200 bar and maximum rate of pressure at 30 bar/CAD IMEP net 17.4 bar IMEP gross 20.4 bar Animation Power

  50. Fuel consumption and emissions

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