Diesel HCCI Results at Caterpillar

Transcription

1 Diesel HCCI Results at Caterpillar Kevin Duffy, Jonathan Kilkenny Andrew Kieser, Eric Fluga DOE Contracts DE-FC5-OR2286, DE-FC5-97OR2265 Contract Monitors Roland Gravel, John Fairbanks DEER Conference Newport, RI August 27, 23

2 Outline Review challenges Development process Recent progress Multi-cylinder engine Operating range expansion Advanced controls Fuels effects Summary Future plans

3 HCCI Engine (Homogeneous Charge Compression Ignition) HCCI - The Challenge Proper air / fuel mixing Limited load range Combustion phasing and control Low temperature combustion ultra low emissions

4 HCCI Development at Caterpillar Design FEA Multi Cylinder Testing Single Cylinder Testing System Simulation CAT3D Combustion Model Optical Engine Spray Visualization This project was undertaken pursuant to an agreement with the United States in connection with settlement of disputed claims in an enforcement action under the Clean Air Act

5 Ultra-Low Emissions Particulate (g/hphr) Recent HCCI Results 21 Regulations 24 Regulations NOx (g/hphr)

6 HCCI Engine (Homogeneous Charge Compression Ignition) HCCI - The Challenge Proper air / fuel mixing Limited load range Combustion phasing and control Low temperature combustion ultra low emissions

7 Mixture Preparation Optimization HCCI Tip Progression Additional 9% Smoke Reduction Tip 1 Tip 2 Tip 3 Smoke (AVL) NOx (g/hp*hr)

8 Multi-Cylinder Engine Results Tip A Tip B AVL Smoke Main Timing Main Timing 12 RPM, ~1/4 <.4 g/hphr NOx Tip A Tip B CO (ppm) Tip A Tip B 5 4 Tip A Tip B 3 2 HC (ppm) BSFC 1 Main Timing Main Timing

9 HCCI Engine (Homogeneous Charge Compression Ignition) HCCI - The Challenge Proper air / fuel mixing Limited load range Combustion phasing and control Low temperature combustion ultra low emissions

10 Light Load HCCI Operation Dec and Sjoberg (23) examined low load HCCI operation with fully premixed iso-octane and a GDI system Found as load was reduced (phi<.2), CO increased rapidly due to bulk gas quenching, combustion efficiency decreased to <5% Suggested there is a fundamental low load limit for HCCI driven by these bulk gas quenching phenomena

11 HCCI Idle Operation Timing CO (ppm) NOx (ppm) HC (ppm) IMEPcov BL BL+5deg retard

12 Expanding HCCI Load Range BMEP (kpa) HP C15 Full Load Curve Speed (rpm)

13 HCCI Engine (Homogeneous Charge Compression Ignition) HCCI - The Challenge Proper air / fuel mixing Limited load range Combustion phasing and control Low temperature combustion ultra low emissions

14 Controlling Cylinder-to-Cylinder Variability Charge air temperature variability, outside cylinders get less fresh charge Intake valve actuation available on current ACERT TM engines Back-flow During Valve Timing Strategies Fresh Charge Inferred Temperature Distribution

15 Cylinder to Cylinder Balancing Intake valve actuator trim strategies used to phase combustion properly Allows for higher power levels to be achieved Untrimmed Trimmed

16 Combustion Control System Interaction VGT Position Back Pressure Cylinder Pressure Compression Ratio Boost Pressure A/F Ratio Emissions Heat Rejection Rise Rate Manifold Temp BSFC Exhaust Temperature Injection Timing Desired Speed/ Power

17 Controls Development Process Performance/Emissions Data rpm 15 rpm Neural Network learns the interactions AVL Smoke BSNOx (g/hphr) Engine Settings 15 rpm, 1/4 load 18 rpm In-Cylinder Pressure Data Training Data for Neural Network VGT Boost Manifold Position Pressure Temp Exhaust Back A/F Ratio Temperature Pressure BSFC Cylinder Emissions Pressure Injection Heat Rejection Timing Compression Ratio Rise Rate Optimum Settings Desired Speed/ Power Sensors Heat Release Rate Actuators Crank Angle (Deg) Rapid Prototype Controller

18 Sample Neural Net Models NOx from ICP Pmax from EC parameters CO from ICP+EC parameters PM from ICP+EC parameters

19 Two-Stage Combustion with Diesel Fuel Question: Can fuel properties be manipulated in such a manner to advantageously effect cool flame chemistry and combustion phasing? Rate of cool flame chemistry varies with load. Induction time affected by residual content, IVA, boost, etc. Amount of cool flame activity affects main combustion timing and rise rate.

20 Study Fuels Effects on HCCI Combustion Teamed with major oil industry partner Developed matrix of 12 fuels Diesel and gasoline like fuels Vary ignition quality and volatility In stock or easily blended fuels Test in single cylinder (~1 wk/fuel) Preliminary (CAT only in-house) results presented here for high and low cetane # fuels

21 Effect of Cetane Number 12 rpm, ~1/4 load, equal fuel mass, advanced timing PCYL (MPa) Higher CN Lower CN Heat Release (kj/m3) Higher CN leads to: -earlier cool flame and main ignition -4% increase in peak cylinder pres -2x increase in cyl pres rise rate 12 rpm, ~1/4 load, equal fuel mass, timing=nox takeoff CAD PCYL (MPa) Higher CN Lower CN Heat Release (kj/m3) CAD

22 Emissions and BSFC Impact BSNOx (g/hphr) rpm, ~1/4 load AVL smoke <.5 all points Injection Timing (deg btdc) Timing Retard Higher CN Lower CN BSFC (g/kwhr) 12 rpm, ~1/4 load Higher CN Lower CN Timing Retard Injection Timing (deg btdc)

23 Highly Competitive BSFC BSFC (g/kw-hr) ACERT 27 Demo 21 HCCI NOx (g/hp-hr) BSFC (g/kw-hr) ACERT 27 Demo 21 HCCI NOx (g/hp-hr)

24 Conclusions HCCI demonstrated up to 16 bar BMEP Single and multi-cylinder engines running Highly competitive thermal efficiencies Stable HCCI combustion obtained at idle, light load conditions Meeting controls issue on all fronts Full control system characterization under development using neural network models with in-cylinder pressure sensing Cylinder variability observed, VVT appears to be viable trimming mechanism Fuels effects (CN) can have significant impact on performance/emissions, higher CN not right direction

25 Next Steps Advanced control algorithm integration on multicylinder Expand load limits further HCCI fuels effects testing Continue advanced fuel and air system development