Estimation of the Residual Gas Fraction in an HCCI-engine using Cylinder Pressure

Abstract: The residual gas fraction is an important parameter to get good performance with high efficiency and low emissions in the HCCI-engine. The goal in this thesis is to formulate an algorithm for estimation of the residual gas fraction based on the cylinder pressure. The estimation is improved if also the exhaust gas temperature is used together with the cylinder pressure. The formulated algorithm has then been tested on data from a single cylinder engine running in HCCI-mode during steady state conditions. An error of 4% was noted compared with the residual gas fraction obtained from simulations. The thesis also investigates the effects of some possible error sources.