Thermo-kinetic modelling of variable valve timing effects on Hcci Engine combustion

Abstract

In this study the effects of variable valve timing on the combustion of a Homogeneous ChargeCompression Ignition (HCCI) engine have been analysed using a new modelling approach for HCCIengine cycle. A novel sequential modelling platform is developed using a combination of detailed multi -zone thermo- kinetic combustion model, 1D intake flow model and exhaust gas flow model. The newmodel utilizes CHEMKIN- PRO and GT - POWER software along with in- house exhaust gas flow model.Experimental data from a single-cylinder HCCI engine is used to validate the model. Validation resultsshow that the model can predict combustion phasing and Indicated Mean Effective Pressure (IMEP)with average errors of 1.1 crank angle degr ees (CAD) and 0.3 bar, respectively. The experimentallyvalidated model is then used to investigate the effects of intake valve timing on HCCI auto - ignitionradicals, zonal temperature, combustion phasing, IMEP, and exhaust emissions.