The Usefulness of Negative Valve Overlap for Gasoline Partially Premixed Combustion, PPC

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceeding

Abstract

Partially premixed combustion has the potential of high efficiency and simultaneous low soot and NOx emissions. Running the engine in PPC mode with high octane number fuels has the advantage of a longer premix period of fuel and air which reduces soot emissions, even at higher loads. The problem is the ignitability at low load and idle operating conditions.

The objective is to investigate the usefulness of negative valve overlap on a light duty diesel engine running with gasoline partially premixed combustion at low load operating conditions. The idea is to use negative valve overlap to trap hot residual gases to elevate the global in-cylinder temperature to promote auto-ignition of the high octane number fuel. This is of practical interest at low engine speed and load operating conditions because it can be assumed that the available boost is limited. The problem with NVO at low load operating conditions is that the exhaust gas temperature is low. While an increase of NVO potentially increases the in-cylinder temperature at intake valve closing, increasing NVO also increases the EGR fraction which lowers the global in-cylinder temperature. The question is to what extent NVO can be used to extend the low load operating region. Investigations on the effect of the glow plug are also included.

The experimental engine is modeled with the engine simulation tool AVL Boost to retrieve information about trapped residual gas fraction and in-cylinder temperature with varying NVO and load at low engine speed and load operating conditions. Measured experimental data is used as input to the engine simulation model at all operating conditions. Measured model inputs include valve lift curves, in-cylinder pressure trace and calculated heat-release profiles.

Details

Authors
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Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Mechanical Engineering

Keywords

  • Internal Combustion Engines, Partially Premixed Combustion, Negative Valve Overlap
Original languageEnglish
Title of host publicationSAE Technical Paper Series
PublisherSociety of Automotive Engineers
Publication statusPublished - 2012
Publication categoryResearch
Peer-reviewedYes
EventSAE 2012 International Powertrains, Fuels & Lubricants Meeting - Malmo, Sweden
Duration: 2012 Sep 182012 Sep 20

Publication series

Name
ISSN (Print)0148-7191

Conference

ConferenceSAE 2012 International Powertrains, Fuels & Lubricants Meeting
CountrySweden
CityMalmo
Period2012/09/182012/09/20