Dieseline/multi-fuel Combustion for HCCI Engines

Transcription

1 Dieseline/multi-fuel Combustion for HCCI Engines Hongming Xu & Miroslaw Wyszynski The University of Birmingham IEA-28th TLM, Heidelberg, August 13-16, 26

2 Presentation Outline Research background Present objectives Research engine setup Results and discussion Conclusions Future prospects 2

3 CHARGE/CHASE Project Outline CHARGE (Controlled Homogeneous Auto-ignition Reformed Gas Engine), 2 yrs DTI sponsored, Jag/total funding = 42/84K concluded 28/4/4 Facilitate natural gas HCCI using fuel reforming Reviewed by UK EPSRC: Tending to International Leading CHASE (Controlled Homogeneous Auto-ignition Supercharged Engine) 3 yrs DTI sponsored, Jag/total funding = 72/1,539K) Kicked-off 28/4/4 Expand gasoline HCCI window Apr/2 partners: Apr/4 Jaguar Cars, Birmingham University Johnson Matthey, MassSpec UK National Engineering Laboratory Race Technology 3 Apr/7

4 Research Partnership Project Project leader, leader, engine engine and and optical optical work work Reforming Reforming catalyst catalyst development development Race Technology NEL Engine Engine and and reforming reforming experiment experiment 4 MS MS support support

5 SE Next Generation (24-27) Extension by boosting Boosting Thermal Managem t Lean-burn Current HCCI Reforming Aftertreatm t tension by fuel reforming Engine speed Main objective Extend the operating window of Gasoline HCCI using combination of boosting, exhaust gas fuel reforming, and total thermal management.

6 single cylinder research engine Engine type (Medusa base) Bore x Stroke (mm) Connecting Rod Length (mm) Valve diameters and lift Geometric Compression Ratio Fuelling type 4 - stroke, single cylinder, 4 valve, pent-roof head 8 x / 24.1 mm 3 mm for NVO (8 mm standard) 1.4 for cold NVO (15. for heated intake standard valve events) liquid port-injected, injection at 3 bar (gauge)

7 ain objective - Evaluate the effect of fuel composition and ontrol of engine parameters on the auto-ignition process of atural gas in automotive engines cept of CHARGE/CHASE (22-27) ormed natural gas (test data) Modelling of the effect of fuel property

8 missions for HCCI fuel reforming (NG) Hydrogen enriched HCCI has a lower NOx emission level and load limit than normal HCCI, with additional effect from reforming

9 ld 1st dual cam profile switching engine Valve lift (mm) Standard CAI J1R Crank angle ( CA) Exhaust VCT Intake VCT

10 ercharged Thermal Management System

11 rd reformer for the Jaguar AJV6 engine

12 e-by-cycle & cylinder-to-cylinder variations Cylinder 6 Cylinder 1 Cylinder 6 Cylinder 1

13 seline research objectives Gasoline, diesel and a variety of alternative fuels are all ssible fuels for HCCI combustion but none of them as a gle fuel has proved to be able to enable a satisfactory erating window. Gasoline and diesel fuels, the most widely supplied ain fuels, have indeed very different but complimentary operties. Gasoline, which has high volatility but low itability, is generally produced as a high octane number el. The Diesel fuel, on the other hand, has a high cetane mber with larger carbon content and heavier molecular ight with low volatility, is better suited to auto-ignition t often requires a lower compression ratio.

14 sent research o investigate the HCCI combustion behaviour of the ixtures of gasoline and diesel as the two fuels with pposite but complementary properties. o investigate whether the two fuels can provide a ompromise HCCI combustion where the ignitability of harge is improved o restrain violent knocking so as to operate the engine n a controllable HCCI combustion mode under a oderate compression ratio

15 t Test matrix Fuel Designation D D5 D1 D2 D5 Fuel Composition Gasoline : Diesel (by mass) 1: 95:5 9:1 8:2 5:5 Intake heating (CR=15.) NVO (CR=1.4)

16 ratio boundary with EGR trapping 3 IMEP (bar) D D5 D2 D5 1.8 Misfiring boundary Excess Air Ratio λ D (pure gasoline), D5, D1 and D5, in NVO HCCI mode, CR=1.4, 15 rpm, unheated intake, low lift cams, NVO = -17 deg.

17 rovement in combustion stability COV of IMEP % D D1 D5 rough running smooth running IMEP (bar) D (pure gasoline), D1 and D5 when engine worked with unheated NVO HCCI mode, CR= 1.4, 15 rpm.

18 Case ve timing case study Cylinder Pressure Trace Negative Valve Overlap EVO MOP EVC 36 IVO MOP IVC 72 Crank Angle Degrees (CAD) Valve timing used in HCCI engine operated in NVO (negative valve overlap) mode. crank angle degrees indicates TDC in the compression / combustion revolution. All IV/EV timings are symmetrical w.r.t. TDC Conditions Inlet valve MOP (CAD atdc) Exhaust valve MOP (CAD btdc) Valve Overlap (CAD) Case Case Case Case

19 easing diesel content, = const, NVO = const D2 D1 D Case3 λ=1.2 D, D1, D2 fuels Case3 NVO = -16 CAD 15 rpm, lambda = Crank Angle Degree (CAD)

20 tion advances with increased load and diesel content 5% burn point (CAD) 5% burn point (CAD) Case3 Case3 D2 D1 D D2 D1 D IMEP (bar) IMEP (bar)

21 P boundary with Variable diesel content Rough Runing Case 3 DO Smooth Runing D1 D IMEP (bar) combustion stability for pure gasoline D is poor, particularly at lower loads, this is also due to retarded combustion phasing D2 offers a very respectable and acceptable COV below 5% over practically its whole range of IMEP

22 mparison of load boundary Case2 Case3 Case Lambda D fuel (gasoline) IMEP (bar) Case1 Case2 Case3 Case4 Case Lambda D2 fuel 3 with D2 fuel, a substantial increase in the upper limit of engine load and a wide an limit of lambda was achieved compared with D fuel. diesel fuel addition at the same Case of NVO also enables richer mixtures and igher loads with sustainable combustion

23 mparison of emissions D2 D5 HC Emission (ppm) D2 D IMEP (bar) IMEP (bar) D2 D rpm, intake temperature 38 K, intake pressure =.1 MPa (abs), CR = 15., standard camshaft with positive valve overlap

24 parison of emissions with varied and load 4 1 CO Emission (%) D 3 D5 2 D IMEP (bar) 1 D 8 D5 6 D2 4 2 HC Emission (ppm) D D5 D IMEP (bar) 15 rpm, unheated intake, low lift cams, NVO = -17 deg, varied

25 x variation when 5% burn kept at TDC NOx Emission (PPM) D D2 Case5 NVO Case4 Case3 Case4 Case IMEP (bar) Case2 Case2 Case1 Case 5 has large NVO, more residual gases in cylinder, higher in-cylinder temperature during the next consecutive cycle. Over-advanced combustion phasing may also be partially

26 parison of fuel consumption 3 SFC (g/ikwh) D2 D Lambda 15 rpm, 5% burn at TDC, stable combustion

27 mary and conclusions e blended fuel namely dieseline makes compromised and optimal to the desired ignition quality, which reduces the dependence of I on EGR trapping or intake heating. dieseline HCCI, the required intake temperature heating can be red by at least 1 degrees compared with pure gasoline operation. diesel addition, appropriate engine conditions can be achieved for line HCCI with EGR trapping for a wide range of CR. HCCI operating region for the unheated NVO can be significantly nded into lower IMEP values and the audible knocking is restrained to highest values of at high load boundary for the highest mixture eratures. The resulting effects make it possible to reduce the NVO val required for stable combustion. possible scale of NVO was extended by up to 4 CAD, the lean limit of da can almost reach up to 2. when engine is operated with a moderate ression ratio (1.4). However this might cause a CO emission penalty at

28 mary and conclusions e indicated specific fuel consumption and CO emissions rease due to decreased pumping losses of recompression and er combustion efficiency. issions of HC and NOx show an interesting improvement pared with gasoline HCCI with optimized engine operating ditions. substantial increase in the upper limit of load range will be ieved without intake heating because of higher volumetric iency resulting from smaller NVO and the presence of less dual gases in cylinder. However this can result in potentially er NOx emissions due to the lower dilution amount present and er combustion temperature.

29 oline and Diesel Engine Technologies are emerging Conventional compression engines Pretreatment + New management Conventional spark-ignition Engines Low Temperature Combustion

30 ti-fuel injection system the future of new engines? computer controlled ur printer can print urful pictures using iginal coloured inks we have 3 different type of s, why cant a CPU controlled injection system supply quired fuel colour (property) printing a beautiful picture for optimised engine ration at varied conditions? imply, a multi-channel fuel nozzle is required at gas

31 knowledgements The authors would like to acknowledge the assistance and cooperation of the colleagues and coworkers in the Future Power Systems Group at the University of Birmingham, especially Dr S Zhong as academic visitor. The support from Jaguar in relation to the present research work is also gratefully acknowledged.