Analysis of the Influence of Inlet Temperature on Oxy-Fuel Combustion in an HSDI Diesel Engine

Carbon Capture and Storage (CCS) techniques in combination with oxy-fuel combustion have been applied as an effective way to achieve nitrogen-free combustion and zero-carbon emissions. The present study has been carried out computationally in the framework of a European project (RIVER) (funded by Interreg North-West Europe) to explore the effect of intake charge temperature on oxy-fuel combustion in an HSDI diesel engine under HCCI combustion mode. Experimental data obtained from a Ford Puma common-rail diesel engine for a conventional part-load condition at 1500 rev/min and 6.8 bar IMEP have been used to validate the CFD model. To simulate the combustion process of HCCI, a reduced chemical n-heptane-n-butanol-PAH model has been adopted. The model has 349 elementary reactions and 76 species. The simulation has been carried out at five different intake charge temperatures (140°C, 160°C, 180°C, 200°C, and 220°C) and five different intake oxygen percentages (15%, 17%, 19%, and 21% v/v). Results show that an accurate intake temperature adjustment is necessary with the implementation of oxy-fuel HCCI combustion using diluent strategies. By raising intake charge temperature, combustion starts earlier along with shorter main stages which result in a reduction in IMEP and an increase in ISFC and by reducing it, combustion stability deteriorates leading to incomplete combustion.