Impact of the Operation Strategy and Fuel Composition on the Emissions of a Heavy-Duty Diesel Engine

Transcription

1 Impact of the Operation Strategy and Fuel Composition on the Emissions of a Heavy-Duty Diesel Engine Dr. C. Barro LAV / Vir2sense M. Parravicini LAV Prof. Dr. Boulouchos LAV

2 Outline Motivation Testbench Results Conclusions 2

3 Motivation PM Bio fuels / synthetic fuels offer a beneficial trade-off behaviour (i.e. soot formation reduction due to oxygen or reduced aromatic content) SFC CO 2 Euro 6 Euro 6 NOx NOx Reduction in lower heating value does not allow an investigation of the phenomenological emission characteristics of the fuel used, due to changes in the injection parameter Goal: Investigation of operating strategy options using different fuels under similar injection characteristics (fuel pressure, duration of injection) and cost functions to account for various engine component setups

4 MTU 396 Engine specifications Displacement 3.96 L Bore/Stroke 165/185 mm Compression ratio Valves 2 Intake 1 Exhaust Test bench limitations Intake pressure 4.5 bar Intake temperature 20 C C Exhaust temperature 700 C Fuel supply EGR Injection pressure 1600 bar # of fuel pumps 2 Injector nozzle 7 x 0.24 mm 8 x 0.24 mm External roots blower < 8% intake O 2 Exhaust analysis NOx/CO/CO2/O2/HC Standard Soot FSN / DMS 500 Experimental Setup

5 Overwiev: Operating Conditions Diesel 7-Hole Nozzle Base (reference) 7-Hole Nozzle EGR variation 8-Hole Nozzle Base OME Blend 8-Hole Nozzle Base 8-Hole Nozzle EGR variation 8-Hole Nozzle SOI variation Diesel: OME: LLLLLL = 43.5 MMMM/kkkk ρρ = 827 kkkk/mm 3 AAAAAA sssssssssss = 14.5 LLLLLL = 19.4 MMMM/kkkk ρρ = 1046 kkkk/mm 3 AAAAAA sssssssssss = 6 OME: Polyoxymethylene dimethyl ether (also POMDME) Ca. 22% OME for volumetric Blend LHV ~8/7 * LHV Diesel 1) 1) E. Jacob

6 Results: Heat Release Rate Comparison 700 n nozz =7, Diesel, DOI e =2ms Diesel 7-Hole Nozzle Base (reference) 7-Hole Nozzle EGR variation 8-Hole Nozzle Base Injection rate, HRR [J/ CA] n =8, Diesel, DOI nozz (n nozz =8, Diesel, DOI e =2.01ms =2.01ms) 7/8 e CA [ ] OME Blend 8-Hole Nozzle Base 8-Hole Nozzle EGR variation 8-Hole Nozzle SOI variation Injection rate, HRR [J/ CA] n nozz =7, Diesel, DOI e =2ms n =8, B83, DOI nozz (n nozz =8, Diesel, DOI e =2.012ms =2.01ms) 7/8 e CA [ ] 6

7 Results: Specific Emissions Comparison Diesel 7-Hole Nozzle Base (reference) 7-Hole Nozzle EGR variation 8-Hole Nozzle Base OME Blend 8-Hole Nozzle Base 8-Hole Nozzle EGR variation 8-Hole Nozzle SOI variation 7

8 Results: Compensation for Auxiliaries Diesel Hole Nozzle Base (reference) High EGR fuel penalty No EGR fuel penalty 7-Hole Nozzle EGR variation Soot [g/kwh] 0.05 Penalties for energy consumption of full engine auxiliaries (i.e. EGR, Turbocharger, DPF, SCR) NO [g/kwh] x Example EGR fuel penalty AISEC [MJ/kWh] NO x [g/kwh] 8

9 Results: Compensation for Auxiliaries Cost Function DPF SCR EGR Turbo Diesel Blend B83 EURO 6 limit IMEP Total DPF o SCR o EGR o Raw soot emissions Raw NOx emissions EGR mass Turbocharger o IMEP o Exhaust enthalpy HP cycle efficiency Cost function Soot [a.u.] [g/kwh] EGR [%] NO x [g/kwh] 9

10 Results: Compensation for Auxiliaries OME blend with variation in EGR penalty DPF SCR EGR Turbo Lower DPF cost ratio due to reduced raw soot emissions Cost function [a.u.] IMEP Total 0.05 OME blend with later SOI Higher DPF cost ratio and lower SCR cost ratio due to shifted trade-off behaviour Cost function [a.u.] EGR [%] 0.3 DPF SCR 0.25 EGR Turbo IMEP 0.2 Total EGR [%] 10

11 Results: Cost Weight of the Strategies Comparison of Diesel Diesel OME blend Diesel OME blend with later SOI Equal cost function for all cases Fuel costs / fuel CO 2 not included Diesel case is worse due to higher raw emissions and lower indicated efficiency Best strategy option depends on auxiliary consumption Best available option in the calculated example with later SOI Cost function [a.u.] Diesel Blend Blend late SOI EGR [%] 11

12 Conclusions A flexible testbench has been set up to compare combustion and emission characteristics of different fuels and strategies Combustion characteristics of different fuels lead to a different trade-offs Different engine setup strategies have been analysed, using a cost function for auxilaries The optimum operation of an engine depends on the engine set up, the operating condition and the fuel used Outlook A model based approach is under development (including emission modelling of various fuel blends) to allow strategy and component setup optimization 12

13 Acknowledgements Co-Authors, for their contributions Swiss Federal Office of Energy, for the financial support You, for your kind attention 13