Direct Biogas Injection in a Hybrid Powertrain Engine
Harald Stütz
Transport Fuels: Crucial factor and driver towards sustainable mobility R&D-projects, research institutions and funding programs in Austria, Europe and global cooperation within the International Energy Agency
Vienna, 28.05.2008 in cooperation with Joint Research Project “Virtual Biogas”
Our Work Package: Agriculture Feasibility of upgraded biogas as Biogas production a fuel for passenger cars Investigation of different gas qualities in view of combustion quality in engine tests Biogas upgrading Extended driving range and Feed-in to natural gas grid minimized CO 2 emission of gas vehicles Improved engine efficiency and fuel consumption by optimized, monovalent, turbocharged Biogas delivered to consumer “virtually” gas engine with direct fuel injection Further fuel saving potential by hybrid powertrain
Use of biogas in gas vehicles Project Partners: AVL List GmbH Biogas Bruck/Leitha GmbH & Co KG Proof of feasibility and cost optimization Vienna University of Technology of all steps of value added chain Axiom Angewandte Prozesstechnik GmbH OMV AG
Rethinking Propulsion. 2 Direct Gas Injection
Multipoint Gas Injection Direct Gas Injection
spark plug
tank 200 bar λ-sensor throttle
air refueling
exhaust gas
fuel gas injection multipoint gas distribution filter pressure safety Piston bowl depth: gas injection directly into Squeezing- injection rail regulator valves combustion9mm chamber into manifold Zone: 9mm
~10% higher volumetric efficiency due to eliminated intake air displacement effect
Rethinking Propulsion. 3 Main Potential of a CNG/Biogas Powertrain
Potential of methane in general: very low pollutant emission level particular high knock resistance (Methane nb. 100 ≈ Octane nb. 120) allows higher compression ratio improved engine efficiency
25% lower CO 2 emission due to better H/C ratio compared to gasoline Potential of direct gas injection: no intake air displacement by fuel gas engine efficiency can be higher than gasoline engine (but lower than Diesel) extended driving range insensitive against variation in fuel gas quality Potential of biogas: particular high potential to substitute fossil fuels due to high yield per acreage wide variety of raw materials can be used for production less direct competition with food production compared with other biofuels utilization of existing, well-developed natural gas grid for distribution consistency of upgraded biogas (>96% methane) is more stable than CNG, does not contain higher hydrocarbons
Rethinking Propulsion. 4 Biogas Upgrading
Gas permeation technology
to achieve ÖVGW G31/G33 feed-in standard
Methane
CO -rich permeate Membrane 2 (aromatic polyimide)
Pre-desulfurization is necessary! Source: Michael Harasek, TU Vienna
Rethinking Propulsion. 5 Biogas Upgrading
2-stage gas permeation facility in Bruck/Leitha, in operation since 2007
CH 4 concentration is with >96% higher than that of some natural gases, type H
Rethinking Propulsion. 6 Investigated Gas Mixtures
Gas mixtures used for engine tests
Partly Upgraded Biogas (79% CH ) Semi Upgraded Biogas (85% CH ) 4 4 Fully Upgraded Biogas (96% CH 4) Biogas-H 2 Mixture (53% CH 4) O2 O2 N2 O2 N2 N2 CO2 0.73 [% ] 0.5 1.0 CO2 0.5 1.0 0.65 VOL 2.5 CO2 14.0 19.5 H2 27.0
CH4 53.0
CH4 CO2 CH4 79.0 CH4 20.0 84.5 95.5 Methane number: 119.8 114.2 102.6 86.2
Raw Biogas (min. 55% CH 4) Raw Biogas (max. 65% CH 4) Raw biogas scatter band N2 N2 H2 H2 O2 1 O2 1 [% ] 1 1 Bruck/Leitha VOL 0.5 0.5
CO2 32.5
CO2 42.5 CH4 55.0
CH4 65.0
Rethinking Propulsion. Methane number: 141.6 131.8 7 Single Cylinder Research Engine
Engine test runs on AVL test rig
Configuration Otto Gas DI Bore [mm] 86 Stroke [mm] 86 Cylinder Displacement [cm 3] 499.6 Compression Ratio [-] 12.9
Rethinking Propulsion. 8 Prototype Injector for Research
Hydraulic direct gas injector designed by AVL
Gas
high flow rate Gas very flexible injection control
Rethinking Propulsion. 9 Injection Strategy at Full Load
IMEP at stoichiometric full load, naturally aspirated
Comparison of direct injection strategy for different gas mixtures The effect of intake air CNG or upgraded biogas 53%CH4, 20%CO2, 27%H2 79%CH4, 19.5%CO2 1100 displacement for manifold gas injection can be seen.
1050 Direct injection can compensate a low gas quality (= low energy density). 1000 +20%
950 IMEP [kPa] IMEP
900
850
800 Early direct Injection (while aspiring stroke) Late direct Injection (after intake closing) Injection Strategy
Rethinking Propulsion. 10 Combustion Behavior at stoichiometric part load at lean part load 2000rpm / 3bar IMEP / Lambda=1 2000rpm / 3bar IMEP / Lambda=1.6
30 30 29.05 CNG/upgraded biogas, 96% CH4 84.5%CH4, 14%CO2 CNG/upgraded biogas, 96% CH4 84.5%CH4, 14%CO2
53%CH4, 20%CO2, 27%H2 79%CH4, 19.5%CO2 53%CH4, 20%CO2, 27%H2 79%CH4, 19.5%CO2 25 25 22.27
20 20
14.75 15 15
12.07 11 10.98 9.35 10 10 8.38
5 5 2.6 2.13 2.07 0.91 0.92 1.14 1.15 1.13
0 0 CombustionCoV [%] Stability IgnitionIgnition delay IGN-2% Delay [°CA] CombustionCoV [%] Stability IgnitionIgnition delay IGN-2% Delay [°CA] (CoV) [%] (IGN - 2% MFB) [°CA] (CoV) [%] (IGN - 2% MFB) [°CA]
The influence of a low biogas quality is surprisingly small due to direct gas injection. A hydrogen fraction accelerates and stabilizes the combustion. Hydrogen can overcompensate the influences of a high inert gas content. Hydrogen further improves the EGR compatibility.
Rethinking Propulsion. 11 New Piston Layout required
A fully optimized gas engine leads to significantly higher piston loads.
typical gasoline piston typical diesel piston
- optimized for high engine speed - optimized for high peak firing pressure - low weight - high weight - small compression height - large compression height - no cooling duct - cooling duct - small piston pin diameter - large piston pin diameter
For optimized gas direct injection a solution for high peak firing pressure, high temperature induction and high engine speed has to be found! Rethinking Propulsion. 12 Cooled Light Weight Piston for 145 bar PFP
Optimized, double oil-cooled aluminum cast piston for turbocharged gas direct injection with high compression ratio and 145 bar peak firing pressure
piston ring carrier
region of highest thermal load piston pin diameter oil cooling duct cooling of piston bottom oil supply (below spark plug) between gasoline by oil spray for cooling duct and diesel
Rethinking Propulsion. 13 Optimized Four Cylinder Gas Engine
Thermodynamic engine cycle simulations with AVL BOOST
complete engine: 4 cylinder BOOST model
single cylinder test bed results
Rethinking Propulsion. 14 Full Load Curves
4 cylinder 2.0L gas DI TCI engine
comparison to average Gasoline DI engine
22 240 24 Internal Mixture Preparation (direct gas injection) GasolineGas Concept Concept 22 20 220 External Mixture Preparation (manifold injection) Comparable Gasoline Engine 20 18 200 18 16 220 16 180 BMEP[bar] 14 200
BMEP[bar] 14 160 12 180
12 140 160 140 10 120 120 P [kW] P 100 100 P [kW] P 370 80 250 80 350 60 240 60 330 40
310 BSFC 20 230 40 CorrectionHeizwert - Korrektur: of Heating Value: BSFC_korr CorrectionHeizwert - Korrektur: of Heating Value: 290 0 BSFC_korr= BSFC * Hu_CNG / Hu_Gasoline BSFC_korr= BSFC * Hu_CNG / Hu_Gasoline 220 20 270
250 Lower Heating Value: 48476 kJ/kg 210 0 Lower Heating Value: 48476 kJ/kg BSFC[g/kWh]
BSFC[g/kWh] Stoich. A/F-Ratio: 16.670 Stoich. A/F-Ratio: 16.670 230 200 210 Ambient Conditions: Ambient Conditions: p = 1.000 bar p = 1.000 bar 190 T = 25.0 °C 190 BSFC T = 25.0 °C BSFC 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 Engine Speed [rpm] Engine Speed [rpm]
Rethinking Propulsion. 15 Fuel Consumption - Stratified Operation
Direct gas injection allows lean stratified engine operation. Stratification provides the highest efficiency potential.
fuelVerbrauchskennfeld consumption map, 4 4-cylinder,Zylinder homogener homogeneous Betrieb mode fuelVerbrauchskennfeld consumption map, 4 4-cylinder,Zylinder homogener homogeneous und andgeschic strahtetertified mode Betrieb 17 17 195 homogeneoushomogener Betrieb mode 195
15 15
0 0 0 13 2 0 13 2
11 11
2 9 05 9 205 210 210 BMEP [bar] BMEP 215 [bar] BMEP 215 22 7 0 7 220 225 225 230 230 235 240 235 245 240 250 245 5 2 255 5 250 265 60 5 270 stratifiedgeschichteter mode Betrieb 25 275 260 290 280 65 285 2 270 300 275 3 310 3 280 285 90 320 2 330 300 60 3 310 340 0 50 3 10 310 1 350 35 3 1 320 1000 1250 1500 1750 2000 2250 2500 1000 1250 1500 1750 2000 2250 2500 n [1/min] n [1/min] evaluated with AVL BOOST Rethinking Propulsion. 16 Different Gas Hybrid Powertrain Concepts
Complete vehicle simulations with AVL CRUISE. Different hybrid concepts on the basis of engine simulation (BOOST) results.
17 homogeneoushomogener Betrieb mode 195
15
0 0 13 2
11
9 205 210
BMEP [bar] BMEP 215 7 220 225 230 235 240 245 5 250 5 stratifiedgeschichteter mode Betrieb 25 260 5 26 270 275 3 280 285 290 300 0 310 310 31 1 320 1000 1250 1500 1750 2000 2250 2500 n [1/min]
Vehicle type: Middle class Inertia weight: 1590 kg Engine displacement: 2.0 L Rethinking Propulsion. 17 Simulated Hybrid Configurations
Different Types of Hybrid Characteristics Powertrains strategies Electric drive Electric Braking Braking Energy Recuperation Recuperation of Load point shifting Hybridisation Level
BASIS FZG Ref. Reference vehicle, standard powertrain, no hybridization - - - -
HEV0 BSG The E-machine is mounted to the combustion engine via a belt transmission Micro/Mild Lim. No No
HEV1 CSG 1 Crankshaft Starter Generator system with 1 clutch Mild Lim. No No
HEV2 CSG 2 Crankshaft Starter Generator system with 2 clutches Mild/Full Yes Bat. size Yes
HEV3 TISG Integrated Starter Generator system with 1 clutch Mild/Full Yes Bat. size Yes
HEV4 TTR The E-machine is mounted to the second axle (4WD) Mild/Full Yes Bat. size Yes
The engine power is split into a mechanical and a mechanical/electrical part using HEV5 PS Full Yes Yes Yes two E-machines to control and optimize the power split ratio and efficiency.
The engine power is completely transformed into electrical power, no direct HEV6 SH Full Yes Yes Optimal mechanical power transfer; the E-machine is mounted to the drive axle
IDEAL ICE HEV IIH Always best engine functioning point; Perfect power transmission & storage
Rethinking Propulsion. 18 CO 2 Emission Potentials
reference weight 1590 additional weight kg +220 kg => 1810 kg
NEDC CO 2 emission Characteristics [gCO 2/km] Gasoline Gasoline Gas stratified Gas stratified Gas Gas Homogenous Gas Homogenous Gas BASIS FZG Ref. Reference vehicle, standard powertrain, no hybridization 160 119 131 168 125 137 HEV0 BSG The E-machine is mounted to the combustion engine via a belt transmission 155 102 113 162 106 117 HEV1 CSG 1 Crankshaft Starter Generator system with 1 clutch 155 100 111 161 104 114 HEV2 CSG 2 Crankshaft Starter Generator system with 2 clutches 132 90 99 138 94 103 HEV3 TISG Integrated Starter Generator system with 1 clutch 132 90 99 138 94 103 HEV4 TTR The E-machine is mounted to the second axle (4WD) 129 87 96 134 91 100 The engine power is split into a mechanical and a mechanical/electrical part HEV5 PS using two E-machines to control and optimise the power split ratio and 116 81 82 126 89 90 efficiency The engine power is completely transformed into electrical power, no direct HEV6 SH 105 69 69 114 74 74 mechanical power transfer; the E-machine is mounted to the drive axle
IDEAL ICE HEV: Always best engine functionning point; Perfect power HEV7 IIH 77 50 50 82 54 54 transmission & storage evaluated with AVL CRUISE
CO 2 numbers are absolute (not distinguished between fossil and biogenic origin) Rated engine power: 180 kW considerable downsizing potential
Rethinking Propulsion. 19 Driving Range Potentials
Tank pressure: 200 bar
Tank capacity: 25kg = 33.03 m³N; upgraded biogas (0.757 kg/m³N) reference weight 1590 additional weight kg +220 kg => 1810 kg
Driving Range [km] Characteristics Gas Gas stratified Gas stratified Gas homogeneous Gas homogeneous Gas
BASIS FZG Ref. Reference vehicle, standard powertrain, no hybridization 544 494 517 474
The E-machine is mounted to the combustion engine via a HEV0 BSG 635 573 609 555 belt transmission
HEV1 CSG 1 Crankshaft Starter Generator system with 1 clutch 647 583 621 566
HEV2 CSG 2 Crankshaft Starter Generator system with 2 clutches 719 654 689 627
HEV3 TISG Integrated Starter Generator system with 1 clutch 719 654 689 627
HEV4 TTR The E-machine is mounted to the second axle (4WD) 744 674 710 646
The engine power is split into a mechanical and a HEV5 PS mechanical/electrical part using two E-machines to control an 799 789 727 719 optimise the power split ratio and efficiency.
The engine power is completely transformed into electrical HEV6 SH power, no direct mechanical power transfer; the E-machine is 938 938 872 872 mounted to the drive axle
Rethinking Propulsion. 20 Contact
DI (FH) Harald Stütz, MSc AVL List GmbH
Address: Hans-List-Platz 1 8020 Graz Austria Tel: +43-316-787-1825 Fax: +43-316-787-189 web: www.avl.com Email: [email protected]
Rethinking Propulsion. 21