Title: Natural gas/diesel RCCI CFD simulations using multi-component fuel surrogates

Authors: Andrew G. Hockett; Greg Hampson; Anthony J. Marchese

Addresses: Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado, USA ' Woodward Inc., Loveland, Colorado, USA ' Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado, USA

Abstract: Previous attempts to model natural gas/diesel reactivity controlled compression ignition (RCCI) engines using single fuel component chemical kinetics have demonstrated difficulties with reproducing the gradual increase in combustion rate observed experimentally. This study investigates whether employing a multi-component vaporisation and chemical kinetics model for diesel fuel can yield closer agreement with experimental combustion rates. Multi-dimensional CFD simulations are compared against an injection timing sweep from a GM 1.9 L diesel engine modified with port injected natural gas. Using the multi-component model for both diesel vaporisation and diesel chemical kinetics resulted in a closer match with experimental heat release rate than using single component diesel chemical kinetics. However, the overly fast combustion rates at ignition could not be completely eliminated. In addition, a parameter study revealed that the simulation results are strongly sensitive to the ratio of components in the diesel fuel surrogate, the injected mass, and the injection velocity.

Keywords: RCCI engines; reactivity controlled compression ignition; CFD; computational fluid dynamics; modelling; dual fuel engines; chemical kinetics; multi-component fuel surrogates; natural gas; diesel; multi-component vaporisation; injection timing; simulation; heat release; combustion rates.

DOI: 10.1504/IJPT.2017.082915

International Journal of Powertrains, 2017 Vol.6 No.1, pp.76 - 108

Received: 10 Aug 2015
Accepted: 07 Mar 2016
Published online: 15 Mar 2017 *

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