Closed-Loop Combustion Control for a 6-Cylinder Port-Injected Natural-gas Engine

Research output: Contribution to journalArticle

Abstract

High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy-duty spark ignition engines. With stoichiometric conditions a three-way catalyst can be used which means that regulated emissions can be kept at very low levels. Obtaining reliable spark ignition is difficult however with high pressure and dilution. There will be a limit to the amount of EGR that can be tolerated for each operating point. Open-loop operation based on steady state maps is difficult since there is substantial dynamics both from the turbocharger and from the wall heat interaction. The proposed approach applies standard closed-loop lambda control for controlling the overall air/fuel ratio for a heavy-duty, 6-cylinder, port-injected natural gas engine. A closed-loop load control is also applied for keeping the load at a constant level when using EGR. Furthermore, cylinder pressure-based dilution limit control is applied on the EGR in order to keep the coefficient of variation at the desired level of 5%. This way confirms that the EGR ratio is kept at its maximum stable level all times. Pumping losses decrease due to the further opening of the throttle, thereby the gas exchange efficiency improves and since the regulator keeps track of the changes the engine all the time operates in a stable region. Our findings show that excellent steady-state performance can be achieved using closed-loop combustion control for keeping the EGR level at the highest level while the stability level is still good enough.

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Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Energy Engineering

Keywords

  • Internal Combustion Engine, Natural Gas, Control
Original languageEnglish
Article number 2008-01-1722
Pages (from-to)1232-1241
Number of pages10
JournalSAE International Journal of Fuels and Lubricants
Volume1
Issue number1
Publication statusPublished - 2009
Publication categoryResearch
Peer-reviewedYes
EventSAE International Powertrains, Fuels and Lubricants Congress - Shanghai, China
Duration: 2008 Jun 23 → …

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