Development and Validation of a Quasi-Dimensional Model for (M)Ethanol-Fuelled SI Engines

Methanol and ethanol are interesting spark ignition engine fuels, both from a production and an end-use point of view. Despite promising experimental results, the full potential of these fuels remain to be explored. In this respect, quasi-dimensional engine simulation codes are especially useful as they allow cheap and fast optimization of engines. The aim of the current work was to develop and validate such a model for methanol-fuelled engines. Several laminar burning velocity correlations and turbulent burning velocity models were implemented in a QD code and their predictive performance was assessed for a wide range of engine operating conditions. The effects of compression ratio and ignition timing on the in-cylinder combustion were well reproduced irrespective of the employed u l correlation or u te model. However, to predict the effect of changes in mixture composition, the correlation and model selection proved crucial. Compared to existing correlations, a new correlation developed by the current authors led to better reproduction of the effects of equivalence ratio and residual gas content and the combustion duration. For the turbulent burning velocity, the models of Damkohler and Peters consistently underestimated the influence of equivalence ratio and residual gas content on the combustion duration, while the Gulder, Leeds, Zimont and Fractals model corresponded well with the experiments. The combination of one of these models with the new u l correlation can be used with confidence to simulate the performance and efficiency of methanol-fuelled engines.