Hongming Xu (Jaguar Cars) Miroslaw Wyszynski (University of Birmingham) Stan Golunski (Johnson Matthey) SAE Homogeneous Charge Compression Ignition Symposium 19-20 September 2005
ACKNOWLEDGEMENTS Contribution to the current research Jaguar Cars - Trevor Wilson, Huiyu Fu, Simon Cryan, Andy Williams, Simon Rudolph, Shadi Gharahbaghi, Stan Wallace and Steve Richardson Birmingham University - Thanos Megaritis, Daniel Yap, and Roy Lehrle Johnson Matthey David James and Sylvain Peucheret UK DTI and EPSRC sponsorship through Foresight Vehicle LINK Projects CHARGE and CHASE /22
Presentation Outline Objectives Project outline Current status Future prospective
What is FORESIGHT VEHICLE FORESIGHT VEHICLE is the UK s prime knowledge transfer network for the automotive industry involving collaboration between industry, academia and Government. The R&D programme aims to promote technology and stimulate suppliers to develop market driven enabling technologies for motor vehicles. The research within the programme is to ensure that future products and technologies meet social, economic and environmental goals, satisfying requirements for mobility, safety, performance, cost and desirability.
UK FORESIGHT projects on HCCI CHARGE (Controlled Homogeneous Auto-ignition Reformed Gas Engine), 2 years (2002-2004) Total funding = 840K (50% industrial contribution) Facilitate natural gas HCCI using fuel reforming CHASE (Controlled Homogeneous Auto-ignition Supercharged Engine) 3 years (2004-2007) Total funding = 1,539K (50% industrial contribution) Expand gasoline HCCI window Apr/02 Apr/04 Apr/07
PCHAREG/CHASE Project Consortium Project leader, leader, engine engine systems Reforming Reforming catalyst catalyst development development Engine-control Thermal-management Engine Engine and and reforming reforming experiment experiment Mass-spectrometry
What are the outstanding issues? Size of HCCI operation envelopes 8 Fuel economy at vehicle level Driver transparent transitions between HCCI and SI NVH and robustness (Customer interest) Cost - engineering (engine upgrade) material (e.g. special valve-train and control) manufacturing BMEP (bar) 6 4 2 0 SI HCCI HCCI SI/CI 0 1000 2000 3000 4000 5000 engine speed (rpm) Schematic illustration of HCCI envelope for a vehicle application
Strategies to enable HCCI Compression ratio control Temperature (and pressure) control Air/Fuel mixture properties EGR trapping/ breathing Injection strategies Ex/in valve strategies Fuel reforming Specially-designed camshaft and valve control Exhaust heat recovery Reaction rate control
CHARGE Project Concept Reformed natural gas (test data) Modelling of the effect of H2 addition Evaluate the effect of fuel composition and control of engine parameters on the auto-ignition process of natural gas in automotive engines with on-board fuel reforming
CHASE Project Concept Extension by supercharging Thermal management Lean-burn Boosting Fuel reforming Current HCCI Extension by fuel reforming Engine speed Engine speed Aftertreatment Extend the operating window of HCCI using combination of boosting, exhaust gas fuel reforming, and total thermal management.
CHARGE/CHASE Research Engines (1) Jaguar Optical engine Engine Type Bore Stroke Compressio n Ratio Fuel system (1) Fuel system (2) Fuel reformer Intake heating 4V, Jaguar V6/V8 82.5 mm 79.5 mm 10.5, 11.3 or 14 Liquid DI or Port injection Gaseous Manifold injection Open loop Electrical, up to 3kw
Flow characterisation with PVO and NVO Positive Valve Overlap IN EX c 5 m/s PISTON CAI 10 20 30 40 50 60 mm 0 0 10 20 30 40 50 60 70 80 mm b d Negative Valve Overlap BDC 1000rpm 225 CAD Wilson et al, 2005
Flame Propagation? High speed imaging of gasoline HCCI combustion development Kodac EM high-speed, 240x50 intensified camera, 4000 fps. Wilson et al, 2005
CHARGE/CHASE Engines (2) Single cylinder Thermal engine Engine Type Bore Stroke Compression Ratio Fuel system (1) Fuel system (2) Fuel reformer Intake heating Medusa 4V 80 mm 88.9 mm 10.5, 12.5 or 13.3 Liquid Port injected Gaseous Manifold injection Closed loop Electrical, up to 3kw
Fuel Reforming (1) - NOx emissions for gasoline HCCI Fuel reforming could extend the low load limit by over 10% Xu et al, 2005
Fuel Reforming (2) Pressure rise rate with H2 addition Natural gas HCCI has a higher rate of pressure rise than gasoline HCCI because of the mixing features of the gaseous fuel with EGR and additional effect from intake heating. Yap et al, 2004
Boosting(1) - Valve strategy for minimum NOx emissions Boosting and EGR selection strategy 1 and 2 have the same engine load but any difference in NOX and fuel economy? Yap et al, 2005
Boosting (2) - NOx reduction with diluted combustion Advance exhaust valve closing and increase boosting pressure allow a significant reduction in NOx emissions with a very little penalty in FC Yap et al, 2005
World 1st dual cam profile switching for HCCI Cam 1 Cam 2 Engine Type Bore Stroke Compression Ratio Fuel system (1) Fuel system (2) Fuel reformer Intake heating Variable Valve Timing AJV6 CHARGE (AJV8 - CHASE) 82.5 (86)mm 79.5 (86) mm (9) 11.3 or 13 Liquid GDI or Port injection Gaseous Manifold injection Closed loop available Intake and exhaust
Modelling HCCI engine combustion and operation K j n i i i i n i i i i i i i hli j j j i i i p T R m dt dt R m dt dv V T R m Q M u dt dt c 1 1 1.., 1 1 Governing equations (similar as in a single-zone model): V T R m P n i i i i 1 Ref: SAE 2001-01-1029 Xu et al, 2005
EGR as combustion phase control Equal EGR rate of 55% Retard Ig. @TDC Retard 55% EGR rate presents the earliest ignition, fastest burning rate and minimum FC line Xu et al, 2003
HCCI Engine modelling ISFC Valve timing IMEP Reduce Best FC Reduce Valve strategy for the best fuel economy with HCCI Xu et al, 2003
Multi-zone modelling of auto-ignition 650 600 case 1 case 2 case 3 mass fract. 45 Case 1 Temperature (K) 550 500 30 15 Mass Fraction (%) 3 450 Case 2 400 0 1 2 3 4 5 6 7 8 9 10 0 Zone number 45 40 35 p ressure ( bar) 30 25 20 Test data 15 case 1 case 2 10 case 3 5 singlezone 0-20 -15-10 -5 0 5 10 15 20 25 30 Crank angle (degree) Case 3 Xu et al, 2005
Optimisation of valve lift and duration Breathing limit Xu et al, 2003
Transitions required for the Jaguar NA V6 CAI/HCCI
Combustion mode transition SI HCCI modelled data test data Xu et al, 2004
Transition optimisation modelling Transient response of throttle, intake and exhaust valves Variation of BMEP, airflow rate and residual mass fraction Xu et al, 2004
Cycle-by-cycle & cylinder-to-cylinder variations Cylinder 6 Cylinder 1 Cylinder 6 Cylinder 1 Without reformed gas With reformed gas
Gasoline and Diesel blending (1) Ignition control Cylinder Pressure (bar) 35 30 25 20 15 10 5 0 D20 D5 D0-40 -30-20 -10 0 10 20 30 40 Crank Angle Degree (CAD) 1500rpm, Dx=(100-x)%gasoline + x% diesel Zhong et al, 2005
Gasoline and Diesel blending (2) expanding HCCI window COV of IMEP % 10 8 6 4 2 Misfire region Misfire region D0 D10 D50 1500rpm 0 1 1.5 2 2.5 3 IMEP (bar) Extension of low load limit Zhong et al, 2005
HCCI what are we after? Conventional Diesel Comp-ignition Fuel with high TAI Late fuelling Heterogeneous Diffusion flame Higher C/R Unthrottled Higher EGR Lean burn L-NOx Higher FE PM... Diesel Or Gasoline?? Conventional SI Spark-ignition Fuel with low TAI Early fuelling Homogeneous Premixed comb Lower C/R Throttled Lower EGR Stoichiometric No L-NOx Lower FE Little PM?..
Gasoline and Diesel Engine Technologies are emerging CR Conventional compression engines 20 15 Pretreatment + New management 10 Conventional spark-ignition Engines Low Temperature Combustion In-direct injection Direct injection High EGR Complex-injection
What could the future engine be like? Mixture pretreated and boosted Multi-fuels management capability Spark-ignition or spark assisted CI at high speed and full load Cycle resolved on line model assisted control Variable strokes and CR with flexible valvetrains Boosted and stratified auto-ignition at low speeds Multi point fuel supply in each cylinder
Conclusions (1) The use of HCCI engines with fuels having a high octane number (poor AI quality) employing EGR trapping alone to enable controlled auto-ignition makes it very difficult to achieve cost-effective vehicle level benefits. HCCI engines will ideally require air boosting and possibly fuel pre-treatment (in one way or another). Thermal management (system- and in-cylinder resolved) is a very promising technology for expanding the HCCI operating window. A new concept of engine control system (e.g. interactive) may be required to handle mixture preparation, ignition and mode transition for the best vehicle performance.
Conclusions (2) The author envisages that gasoline and diesel technologies are merging, leading to a new engine system with a combination of premixed and stratified combustion. Current HCCI developments are to some extent preparing for the advent of other related engine technologies including fully flexible valve-train, variable compression ratio and on-line model based control. Future internal combustion engines will burn any combustible liquid and gaseous fuels with a fuel management system. A new type of fuel dieseline is likely to be required to suit the needs of the new combustion system.
Thank you for your attention Questions?