Waukesha Ignition Improvements to Ignition Improvements to Support High Support High - - efficiency Natural efficiency Natural Gas Combustion Gas Combustion 2005 UW ERC Symposium on Low- Emissions Combustion Technologies for Internal Combustion Engines Corey Honl Sr. Development Engineer Waukesha Engine, Dresser, Inc.
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Ignition Improvements to Support High efficiency … Ignition Improvements to Support High-efficiency Natural Gas Combustion 2005 UW ERC Symposium on Low-Emissions Combustion Technologies
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Waukesha
Ignition Improvements to Ignition Improvements to Support HighSupport High--efficiency Natural efficiency Natural
Gas CombustionGas Combustion
2005 UW ERC Symposium on Low-Emissions Combustion Technologies
for Internal Combustion Engines
Corey HonlSr. Development Engineer
Waukesha Engine, Dresser, Inc.
Waukesha
AgendaAgenda• Who is Waukesha?• What is ARES?• ARES Phase 1 objectives• Current state of natural gas
lean-burn ignition on stationary engines• Test apparatus and fixed characteristics• Prechamber aspects studied and results• Conclusions
Waukesha
Who is Waukesha Engine?Who is Waukesha Engine?
Waukesha
Our Product LineOur Product Line
Waukesha
What is ARES?What is ARES?• The Advanced Reciprocating Engine Systems
program is a multi-year, co-funded research initiative with the DOE to develop high-efficiency natural gas-fueled engines for DPG.
• Consortium members: DOE, Waukesha Engine, Caterpillar, and Cummins.
• Supporting cast: MIT, CSU,UT-Austin, Ohio State, and Purdue; Argonne, NETL, and ORNL.
• Three phase program to achieve 0.1 gr./HP-hr NOx stack emissions and 50% BTE by 2010.
consisting of:– 30+% increase in BMEP (850kW to 1100kW @ 1,800RPM)– leaner combustion than VGF’s λ=1.5 (24:1) AFR to promote
low NOx and improved BTE,– piston redesign for increased strength, turbulence, mfb10-90
control, and CR increase from VGF’s 11:1.– Timing advanced 7° and 10-90 burn rate reduced 7°– major design changes to engine breathing/induction (Miller
cycle), power cylinder, control systems, while maintaining layout to allow crankcase interchangeability with the VGF, and
– all results in BTE increase of 6 percentage points!
• Ignition system objectives: use current WED spark plug; lower variability on mfb, IMEP, and PCP; extended lean limit, and balanced/acceptable spark plug Vd and tip temperatures to achieve desired service life.
Waukesha
Current LeanCurrent Lean--burn State at WEDburn State at WED• Used successfully at
WED with λ’s of 1.75 and 2.0
• The downfalls– extra initial and
maintenance costs,– potential site boosting of
(and need for) secondary fuel source,
– harsh environment for ignition source,
– increased NOxemissions, and
– a more complex system to optimize for durability and serviceability.
Waukesha
WED LeanWED Lean--burn State Cont’dburn State Cont’d• Open chamber combustion
is cheap and simple, but…– slow burn durations (can be
good) with high variability (bad),
– high PCP variability,– high local flow velocities,
especially as squish heights and CR’s get more aggressive,
– high Vd, and– low lean operating limit.
• A compromise is needed...
Waukesha
Test ApparatusTest Apparatus• 6-cylinder VGF™ engine with various
modifications to run intended conditions– Bore X Stroke: 152 X 165 mm– Displacement: 18 Liters (1,096 in3)– Induction: Turbocharged, Intercooled, Draw-through
• MTS® ADAPT cell data acquisition system• Hi-Techniques Win600 high-speed DAS with
REVelation engine combustion analysis software
• Existing J-type PM spark plug with CD-type ignition system
• All other engine hardware remained fixed
Waukesha
Fixed Prechamber CharacteristicsFixed Prechamber Characteristics• A number of prechamber aspects were
fixed due to schedule constraints:– orifice downward angle with regard to fire deck,– direction of prechamber orifice at bottom-center
of prechamber shield,– quantity of prechamber orifices, and– orifice tangential angle magnitude to cylinder
axis.• Further investigation is necessary to
optimize these for alternative bowl shapes, compression ratios, engine speed, bore size, and spark plug electrode design.
Waukesha
MEPP Literature SearchMEPP Literature Search• Published recommended areas, ratios, and trends for
fueled systems helped to organize and direct testing efforts– Total hole cross-sectional area/ prechamber volume,– Prechamber volume/ cylinder clearance volume,– Total hole cross-sectional area/ prechamber cross-sectional
COVIMEP 1.02 0.97 2.341,800 RPM, 16 bar BMEP, 1,800 RPM, 16 bar BMEP, λλ=1.68 =1.68
((9.0% O9.0% O22), and 1 gr./hp), and 1 gr./hp--hr NOhr NOxx timingtiming
Waukesha
Shield Orifice DiameterShield Orifice Diameter• With quantity & location
fixed, this alters cross-sectional area only
• Increased diameter added delay, since decreased pressure differential led to slower main chamber burn
• Combustion variability increased with increasing orifice size, contrary to published works on fueled systems, possibly due to more inconsistent burns from the lower-charged exiting flame jets
Small Medium Large BaselineMFB0-5 14.1 14.8 15.8 18.5