Title: Modelling of the effect of fuel reforming and EGR on the acceptable operating range of an ethanol HCCI engine

Authors: Cathy K.W. Ng, Murray J. Thomson

Addresses: Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto M6S 3W6, Canada. ' Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto M6S 3W6, Canada

Abstract: Homogeneous Charge Compression Ignition (HCCI) engines have great potential in ultra-low NO_x emissions, high efficiency and low particulates. However, HCCI also has a narrow operating range with low power output. We therefore investigated the expansion of the Acceptable Operating Range (AOR) using fuel reforming complemented by Exhaust Gas Recirculation (EGR). The modelled HCCI engine is fuelled with ethanol of equivalence ratio (Φ) of 0.2, 0.4 and 0.5. The AOR must meet both the complete combustion and the maximum NO_x limit (10 ppm). It is found that fuel reforming enhances combustion and extends the complete combustion limit to lower initial temperatures, but also increases NO_x emissions. Since the NO_x limit can be greatly extended by the complementary use of EGR, fuel reforming is not as effective as EGR in widening the operating range at the Φ|s studied. Therefore, fuel reforming is most beneficial when used at lower initial temperatures near the ignition limit.

Keywords: fuel reforming; exhaust gas recirculation; EGR; NOx emissions; nitrogen oxides; acceptable operating range; homogeneous charge compression ignition; HCCI engines; ethanol HCCI; modelling.

DOI: 10.1504/IJVD.2007.013221

International Journal of Vehicle Design, 2007 Vol.44 No.1/2, pp.107 - 123

Published online: 12 Apr 2007 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article