Pre-Chamber Ignition A road towards High Efficiency Natural Gas Engines

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Pre-Chamber IgnitionA road towards High
Efficiency Natural Gas Engines
Ashish Shah, Per Tunestål and Bengt
JohanssonLund University, Sweden
Energirelaterad fordonsforskning
2014 2014-10-08 Gothenberg, Sweden
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Outline

• Introduction
• Motivation and relevance
• Past activities and results obtained
• Future plans

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Introduction

• Administrative details of the project

Name Gas Engine Project
Timeline Phase 6 2010-01-01 to 2013-12-31 Phase 7 2014-01-01 to 2017-12-31
Principal beneficiary Lund University
Other partners in the project Volvo, Volvo Cars, Scania, Cummins, Toyota, Chevron, Loge, Dantec, Swedish Biomimetics and Wärtsilä
Parent program Competence Center Combustion Processes, KCFP
Total support KCFP in total is 101 MSEK for phase 7. The gas engine project part of that is 12.12MSEK.
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Introduction (cont.)

• Aim Develop combustion strategies for internal
  combustion engines operating on gaseous fuels for
  heavy duty applications with comparable or better
  fuel efficiency and operating load range than
  diesel counterparts
• Current focus is on study of alternative ignition
  techniques for heavy duty natural gas engines
  with the following objectives
• Extend the limit of combustion dilution with
  excess air, Exhaust Gas Recirculation (EGR) or
  both.
• Increase the maximum operating load

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Motivation and Relevance

• Natural Gas an attractive alternative fuel
• Lower specific CO2 emissions
• Availability naturally occurring and renewable
  alternatives (e.g. biogas etc.)
• Variety of applications heavy duty on-road
  vehicles (e.g. trucks with LNG), marine engines
  and power generation (e.g. Wärtsilä and MAN
  products)
• Increasing network on natural gas fueling
  stations in Sweden and worldwide.

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Why Pre-chamber ignition?
Problems with open chamber spark ignited engines

• Simple and cheap
• Well developed and mature technology
• Limit of dilution with excess air or EGR
  combustion instability
• High temperature combustion High heat losses
  and NOx emissions
• Maximum load limited by knock
• Knock limited combustion phasing advance loss
  in efficiency

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Why Pre-chamber ignition?
Pre-chamber ignition a possible solution
( 5 Vc)

• Spatially distributed ignition source
• Less affected by cyclic variation of main chamber
  charge motion
• Burning jets provide much higher ignition energy
  than a spark
• Pre-chamber over heating may cause charge
  pre-ignition
• Resulting ignition mechanism is less understood
  due to its fluid dynamic and chemical kinetic
  complexities

( 95 Vc)
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Different strategies
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Experiments and Results obtained so far

• 2011 - 2014

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Experimental Setups
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Experimental Setups (cont.)
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Lean limit with excess air
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Indicated Efficiency
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NOx emissions
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Effect of Pre-chamber geometry
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Effect of Pre-chamber geometry (cont.)
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Conclusions

• A pre-chamber ignition device without additional
  fueling reduces cyclic variations of combustion
  event but is not capable of considerably
  extending the lean limit.
• A pre-chamber with additional fueling can
  considerably extend the lean limit of operation
  and hence improve indicated efficiency and
  reduces NOx emissions
• A larger pre-chamber provides higher ignition
  energy but size is limited by fraction of
  pre-chamber combustion before main chamber
  ignition.

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Future Plans

• Study pre-chamber ignition at full load
  conditions (IMEPg gt 20 bar)
• CFD simulations of pre-chamber jets based on
  experimental pressure data to understand ignition
  mechanism resulting from PC jets
• Optical diagnostics of pre-chamber ignition in
  the Wärtsilä large bore engine through optical
  access to the main chamber and/or pre-chamber.
• Optical diagnostics of knock phenomenon with
  pre-chamber ignition.

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Future Plan (cont.)
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Thank youComments/Questions?

• Ashish ShahPh.D StudentDivision of Combustion
  EnginesLund University
• ashish.shah_at_energy.lth.se