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This article presents a set of formulas for estimating the impact of reformed ethanol fuel on volumetric efficiency in I.C. engines. Both partial and complete usages of reformed ethanol fuel are discussed. Analysis suggests that volumetric efficiency drastically decreases as the level of fuel reforming increases in S.I. engines. Such impact on volumetric efficiency is reduced when the reformed fuel is partially used in diesel engines. A formula for calculating the impact of intake air temperature variation on volumetric efficiency is also presented. This formula is validated against engine simulation on factors such as engine load, speed, displacement, intake air temperature and reformed fuel temperature. Validation results show a maximum of 0.5% error, indicating an accurate approximation and hence high feasibility of this formula.

A new type of dual fuel supply system has been developed. This system is able to economically convert conventional diesel engines into dual-fuel engines like LPG/Diesel engines and CNG/Diesel engines, which are capable of either using single diesel fuel or using dual-fuel including both diesel and CNG fuel or both diesel and LPG fuel. These diesel-LPG engines have been applied to the diesel buses in the public transportation of Guangzhou city, one of the biggest cities in China, owning to their low soot emissions, excellent operating performances and extremely low cost as well. Compared with the diesel baseline engine, it was found that there were a significant reduction in soot emission and an improvement of the fuel consumption with the diesel-LPG engine. Also the strategy on LPG content is discussed in order to meet the demands for soot emission, fuel economy, transient performance and output power at the same time.