Corona Discharge Ignition as long as Advanced Stationary Natural Gas Engines ASME Internal Combustion Engine Division Fall Technical Conference, Long Beach, CA October 25, 2004 Supported by DOE-UREP

Corona Discharge Ignition as long as Advanced Stationary Natural Gas Engines ASME Internal Combustion Engine Division Fall Technical Conference, Long Beach, CA October 25, 2004 Supported by DOE-UREP www.phwiki.com

Corona Discharge Ignition as long as Advanced Stationary Natural Gas Engines ASME Internal Combustion Engine Division Fall Technical Conference, Long Beach, CA October 25, 2004 Supported by DOE-UREP

Marshall, Owen, Music Director has reference to this Academic Journal, PHwiki organized this Journal Corona Discharge Ignition as long as Advanced Stationary Natural Gas Engines ASME Internal Combustion Engine Division Fall Technical Conference, Long Beach, CA October 25, 2004 Supported by DOE-UREP Principal Investigator: Prof. Paul D. Ronney Co-Principal Investigator: Prof. Martin Gundersen Research Associates: Nathan Theiss, Dr. Jian-Bang Liu Graduate students: Fei Wang, Jun Zhao Undergraduate students: Brad Tallon, Matthew Beck Jennifer Colgrove, Merritt Johnson, Gary Norris ASME Paper ICEF2004-891 Motivation Multi-point ignition has the potential to increase burning rates in internal combustion engines (Simplest approach) Leaner mixtures (lower NOx) (More difficult) Higher compression ratios + water injection (higher efficiency with same NOx) (Most difficult) Redesign intake port in addition to combustion chamber as long as lower turbulence since the same burn rate is possible with lower turbulence (reduced heat loss to walls, higher efficiency) Lasers, multi-point sparks challenging Lasers: energy efficiency, windows, fiber optics Multi-point sparks: multiple intrusive electrodes How to obtain multi-point, energy efficient ignition Transient plasma (“pulsed corona”) discharges Not to be confused with “plasma torch” Initial phase of spark discharge (< 100 ns) - highly conductive (arc) channel not yet as long as med Characteristics Multiple streamers of electrons - possible multiple ignition sites High energy (10s of eV) electrons compared to sparks (~1 eV) Electrons not at thermal equilibrium with ions/neutrals Low anode & cathode drops, little radiation & shock as long as mation - more efficient use of energy deposited into gas Enabling technology: USC-built discharge generators (Prof. Martin Gundersen) Georgetown College US www.phwiki.com

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Corona vs. arc discharge Corona phase (0 – 100 ns) Arc phase (> 500 ns) Images of corona discharge & flame Axial (left) in addition to radial (right) views of discharge with rod electrode Axial view of discharge & flame (6.5% CH4-air, 33 ms between images) Characteristics of corona discharges If arc as long as ms, current increases some but voltage drops more, thus higher consumption of capacitor energy with little increase in energy deposited in gas (still have corona, but followed by (almost useless) arc) Corona only Corona + arc

Corona discharges are energy-efficient Discharge efficiency d 10x higher as long as corona than as long as conventional sparks Program objectives Characterize advantages of pulsed corona discharges as long as NG ignition in static combustion chambers Integrate pulsed corona discharge ignition system into stationary natural gas engines 1998-2002 Ford Ranger, 2.5L SOHC 4-cylinder engine, 2 plugs per cylinder (1 conventional plug, 1 corona ignition port) Large-bore stationary natural gas engine Determine if the 3x shorter burn times found with pulsed corona discharges apply to NG engines also If so, exploit the shorter burn times Assess the possibility as long as NOx reduction using additional corona discharges during the exhaust stroke Progress to date Installed new engine in laboratory with two spark plug ports per cylinder (2000 Ford Ranger 2.5L I-4) in addition to converted to NG Updated lab engine data acquisition & control system hardware in addition to software (National Instruments / LabView) Interfaced emissions analyzer with LabView system Implemented student-designed in-cylinder pressure monitoring system on engine Built static test chamber that simulates engine geometry as long as electrode testing Constructed turbulent test chamber in addition to conducted bench tests to characterize effects of turbulence on corona ignition & combustion Studied in addition to characterized minimum ignition energies of corona discharges Developed electrode as long as engine combustion chamber using machinable ceramics Developed trigger system as long as firing corona generator on engine Per as long as med on-engine testing with pulsed corona discharge firing on one cylinder over a range of air/fuel ratios, engine loads in addition to ignition timing

Laboratory test apparatus (constant volume) 2.5” (63.5 mm) diameter chamber, 6” (152 mm) long Energy release (stoich. CH4-air, 1 atm) 1650 J energy release 60,000x minimum ignition energy Energy input as long as ignition is trivial fraction of heat release! Definitions Delay time: 0 – 10% of peak pressure (can be compensated as long as by adjusting “spark advance”) Rise time: 10% – 90% of peak pressure (can’t be fixed with spark advance!) Electrode configurations

Effect of geometry on delay time Spark delay time 2x larger than 1-pin corona ( same geometry) Consistent with computations by Dixon-Lewis, Sloane suggesting point radical sources improve ignition delay 2x compared to thermal sources More streamer locations (more pins, rod) yield lower delay time ( 3.5x lower as long as rod than spark) Benefit of corona on delay time both chemical ( 1.5x) & geometrical ( 2x) Effect of geometry on rise time Rise time of spark larger same as 1-pin corona ( same flame propagation geometry) More streamer locations (more pins, rod) yield lower rise time ( 3 – 4x lower as long as rod than spark), but multi-pin almost as good with much less energy Energy & geometry effects on delay time What is optimal electrode configuration to minimize delay/rise time as long as a given energy Delay time: 2-ring, 4-ring & plain rod similar (all are much better than spark)

Energy & geometry effects on rise time Rise time: 2-ring or 4-ring best Note “step” behavior as long as multi-point ignition at low energies – not all sites ignite (Delay time doesn’t show “step” behavior) Energy & geometry effects (lean mixture) What is optimal electrode configuration to minimize delay/rise time as long as a given energy Delay time: 2-ring, 4-ring & plain rod similar (all are much better than spark) Energy & geometry effects (lean mixture) Rise time: 2-ring or 4-ring best Note “step” behavior as long as multi-point ignition at low energies – not all sites ignite (Delay time doesn’t show “step” behavior)

Simulated engine chamber Test fixture built to same dimensions as engine cylinder in addition to piston crown at TDC to test corona in this geometry Enables initial testing of electrode geometries in addition to visualization of corona Allows optimization of electrode geometries in addition to discharge conditions be as long as e conducting on-engine testing Test Chamber Constructed from Engine Components Allows quicker testing of insulation in addition to electrode configurations without the need to repeatedly remove cylinder head from engine Ignition in simulated engine chamber Delay time actually longer with corona in this geometry (but can be compensated by ignition advance) Rise time 2x faster with corona, with far lower energy input Have ignited with corona only (no arc) up to 10 atm

Turbulent test chamber Turbulence effects Simple turbulence generator (CPU cooling fan + grid) integrated into coaxial combustion chamber, rod electrode Mean flow 11 m/s + turbulence intensity 1 m/s, u’/SL 3 (stoichiometric) Benefit of corona ignition same in turbulent flames – shorter rise & delay times, higher peak P Turbulence effects Similar results as long as lean mixture but benefit of turbulence more dramatic – higher u’/SL ( 8)

Marshall, Owen KASC-AM Music Director www.phwiki.com

Engine experiments at USC 2000 Ford Ranger I-4 engine with dual-plug head to test corona & spark at same time, same operating conditions National Instruments / Labview data acquisition & control Horiba emissions bench, samples extracted from corona – equipped cylinder Pressure / volume measurements Optical Encoder mounted to crankshaft Spark plug mounted Kistler piezoelectric pressure transducer Electrode configuration Macor machinable ceramic used as long as insulator Coaxial shielded cable used to reduce EMI Simple single-point electrode tip, replaceable On-engine pulsed corona discharge ignition system Pulsed corona discharges generated using “pseudospark” switch + Blumlein transmission line, triggered from camshaft 500 mJ/pulse (equivalent “wall plug” energy requirement of 50 mJ spark) Corona electrode in addition to spark plug with pressure transducer in 1 cylinder Switch wired as long as quick change between spark in addition to corona ignition under identical operating conditions Stock timing as long as spark ignition, variable timing as long as corona 3 modes tested Corona only Single conventional plug Two conventional plugs (results very similar to single plug)

On-engine pulsed corona discharge ignition system On-engine results Corona ignition shows increase in peak pressure under all conditions tested On-engine results Corona ignition shows increase in IMEP under all conditions tested

Conclusions Flame ignition by transient plasma (“pulsed corona”) discharges is a promising technology as long as ignition delay & rise time reduction More energy efficient than spark discharges Shorter ignition delay in addition to rise times Rise time more significant issue Longer than delay time Unlike delay time, can’t be compensated by “spark advance” Higher peak pressures Benefits apply to turbulent flames also Demonstrated in engines Higher IMEP (15% – 20%) as long as same conditions with same or better BSNOx Shorter burn times in addition to faster heat release Higher peak pressures Improvements due to Chemical effects (delay time) – radicals vs. thermal energy Geometrical effects – (delay & rise time) – more distributed ignition sites Future Work Install corona ignition on all 4 cylinders Construct corona electrode from ceramic that can withst in addition to higher engine loads – need collaboration with plug manufacturer Test effectiveness of corona as long as NOX reduction in exhaust Implement corona ignition on large bore stationary engine

Marshall, Owen Music Director

Marshall, Owen is from United States and they belong to KASC-AM and they are from  Tempe, United States got related to this Particular Journal. and Marshall, Owen deal with the subjects like Music Programming

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