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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
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Outline Current engines HCCI in general HCCI in Lund, some results Production
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Normal SI engine fuel consumption
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Introduction 100% 99% 98% Catalyst Efficiency SI engine - part load improvement Lean limit 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 0.81.01.5 2.02.55.0
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HCCI vs. GDI and CAI
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Diesel Engine (CI) Large problems with emissions of NOx and PM High fuel efficiency (low CO2 emission)
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HCCI Emissions HCCI 0,01 0,50 0,00 NOx PM * 0,05 USA 2007 AutoTechnology Oct. 2002, p 54
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HCCI in Lund
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HCCI activities in Lund 1.Basic engine studies 2.Laser diagnostics 3.Combustion modeling - Chemical kinetics 4.Closed loop combustion control
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Experimental facilities – single cylinder engines (Volvo 1.6 liter) Scania 2 liter Volvo/Alvar 0.5 liter VCR Old Hot bulb engine
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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
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Current optical engines
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HCCI activities in Lund 1.Basic engine studies 2.Laser diagnostics 3.Combustion modeling - Chemical kinetics 4.Closed loop combustion control
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Volvo TD100 engine
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First VCR system
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Multifuel capability
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Low NOx from HCCI mode
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With Variable Compression Ratio, VCR, the HCCI engine can use ANY liquid or gaseous fuel!
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Basic engine tests…
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The effect of turbulence on HCCI combustion
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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
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Turbulence and geometry effects on HCCI -50-40-30-20-1001020304050 0 0.5 1 1.5 2 2.5 3 3.5 4 Crank Angle [CAD] Turbulence [m/s] Centre Position Disc, LS Head Disc, HS Head Square, LS Head Square, HS Head Turbulence
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Turbulence and geometry effects on HCCI -50-40-30-20-1001020304050 0 1 2 3 4 5 6 7 8 Crank Angle [CAD] Turbulence [m/s] Side Position Disc, LS Head Disc, HS Head Square, LS Head Square, HS Head Turbulence Different scale
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Turbulence and geometry effects on HCCI -50510 0 100 200 300 400 500 600 700 800 Crank Angle [ ° ATDC] Rate of Heat Release [J/CAD] SOC=-2 CAD TDC Disc, LS Head Disc, HS Head Square, LS Head Square, HS Head Rate of Heat Release
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HCCI activities in Lund 1.Basic engine studies 2.Laser diagnostics 3.Combustion modeling - Chemical kinetics 4.Closed loop combustion control
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The influence of Charge Heterogeneity on the HCCI Combustion Process (?)
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Fuel Distribution Prior to Combustion With port-injection With mixing tank
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Tracer PLIF after Auto-ignition With port-injection With mixing tank
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OH PLIF Imaging With port-injection With mixing tank
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High Speed Fuel LIF
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Multi YAG-Laser System t Ordinary laser t Multiple pulse laser 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
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High Speed Camera 8 independent CCD’s, 576x384 pixels10 ns temporal resolution 8 independent CCD’s, 576x384 pixels10 ns temporal resolution Optional image intensifier UV sensitive 1 µs temporal resolution Optional image intensifier UV sensitive 1 µs temporal resolution
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Experimental setup (Scania) Cyl. Volume1951 cm 3 Bore127 mm Stroke154 mm Comp. Ratio16:1 Chamber designPancake FuelEthanol Lambda3.85
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Fuel Tracer PLIF (resolved single-cycle) W16mars_4 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 3.85 Rc: 16:1
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Fuel tracer PLIF from four cycles
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Conceptual model of HCCI Ignition occurs when I reaches a critical value Assuming homogeneous distributions of P,, EGR% and RR:
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Conceptual model of HCCI Effect of heterogeneous air/fuel ratio
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Ignition Temperature
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Turbulence and geometry effects on HCCI Suppression of hot and reactive zones +2 +5.5 +2.5+3+3.5 +4+4.5+5 Single cycle fuel tracer LIF sequences
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HCCI activities in Lund 1.Basic engine studies 2.Laser diagnostics 3.Combustion modeling - Chemical kinetics 4.Closed loop combustion control
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The 6-cylinder HCCI Engine
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Closed loop combustion control, CLCC WaveBook 516 WaveBook 516 NI PCI 6054 Status Calculation PID Controllers HEATERS Injector Actuator Injector Actuator User Inputs PC Pressure Traces Inlet Conditions (p in,T in ) n-heptane i-octane
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Control Parameters -40-20020406080 0 5 10 15 x 10 6 Max Pressure Max dp/dCA Cylinder Pressure [Pa] -40-20020406080 -1000 0 1000 2000 3000 CA50 Heat Release Crank Angle [deg ATDC] Heat Release, Q [J] Controlled CA50 Net IMEP:s Constraints Peak pressure Peak dp/dCA Net heat release
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Combustion phasing=combustion duration
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Combustion Timing Octane Number -5 0 5 10 15 405060708090100 Combustion phasing [CA 50] S = d(CA50%) / d(Octane Number)
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Sensitivity Estimation
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Unstable Operation 0100200300400 0 5 10 15 20 25 30 35 Cycle Index CA50 [°ATDC] Stable Unstable @ 3 bar IMEP @ 4.5 bar IMEP Closed loop control switched off
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Operating range 280 kW (380 hk) HCCI Diesel 16 21 bar 280310 kW HCCI Diesel 16 21 bar 280310 kW
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Typical high load cycle Load limited by Peak Cylinder Pressure at 200 bar and maximum rate of pressure at 30 bar/CAD IMEP net17.4 bar IMEP gross 20.4 bar Animation Power
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Fuel consumption and emissions Engine speed1200rpm BMEP6.06bar Power70.9kW Brake efficiency42.8% NOx0.024g/kWh HC5.9g/kWh CO4.4g/kWh
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And now to something completely different:
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HCCI in production 1890!
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Akroyd Hot Bulb Engine 1890 Photo of model at the Science Museum, London UK Low pressure early direct injection Fuel mix with residual gas and air before combustion Combustion started as temperature increase due to compression
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2-Stroke Hot Bulb Engine Photo of drawing displayed at the Smithsonian Museum,Washington, US
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Efficiency BMEP [bar] b [%] DI PC SC SI HT HB Efficiency 2002-01-0115
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Hot Bulb Engine in Tractor
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Cold Start of Hot Bulb Engine
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Thank you for your attention!
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