The effect of fuel properties on thermal efficiency of advanced spark-ignition engines

Owing to issues of global warming and energy security, improving engine thermal efficiency has become increasingly important today. This paper investigates the impact of high-research-octane-number (RON) fuels on engine thermal efficiency. It is shown that the lean boosted engine has higher potential to increase engine thermal efficiency than naturally aspirated (NA) engines and the combination of lean boosted engine and high-RON fuels gives around 44 per cent engine thermal efficiency. The engine thermal efficiency exceeds a diesel engine's thermal efficiency. Therefore, the combination is expected to be an effective way to reduce CO(2) emissions in the future. In this paper, the high-RON fuels are blended with gasoline components or bio-components. This paper also describes the combustion characteristics of ethanol and butanol. These fuels have good combustion features after the engine has warmed up. However, it is found that butanol gives more severe combustion characteristics under cold conditions.