HCCI Combustion Phasing in a Multi Cylinder Engine Using Variable Compression Ratio

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Abstract

Combustion phasing in a Homogeneous Charge Compression Ignition (HCCI) engine can be achieved by affecting the time history of pressure and temperature in the cylinder. The most common way has been to control the inlet air temperature and thereby the temperature in the cylinder at the end of the compression stroke. However this is a slow parameter to control, especially cycle to cycle. A multi- cylinder engine using Variable Compression Ratio (VCR) for controlling the compression temperature and consequently the combustion phasing is used in the experiments. Operating range in terms of speed and load is investigated in naturally aspirated mode. Trade-off between inlet air temperature and Compression Ratio (CR) is evaluated. Primary reference fuels, isooctane/n-heptane, are used during the tests. High-speed HCCI operation up to 5000 rpm is possible with a fuel corresponding to RON 60. The effect of octane number with and without exhaust cam phasing is also investigated. Brake thermal efficiency of 33% at a maximum load of 4.4 bar BMEP for 2000 rpm is achieved.

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Subject classification (UKÄ) – MANDATORY

  • Other Mechanical Engineering

Keywords

  • Closed-Loop Combustion Control, HCCI, Engine Control
Original languageEnglish
Pages (from-to)2554-2663
JournalSAE Transactions, Journal of Engines
Volume111
Issue number3
Publication statusPublished - 2002
Publication categoryResearch
Peer-reviewedNo