Study on Auto-Ignition Characteristics of Gasoline-Biodiesel Blend Fuel in a Rapid Compression Expansion Machine

Compression ignition (CI) engines are widely utilized on various vehicles nowadays. The CI engines have higher energy conversion efficiency in general than spark ignition (SI) engines mainly due to high compression ratio, lean stratified charge, and no throttling. This study aims to secure stable auto ignition and combustion of gasoline/biodiesel blend fuel when applied to a direct-injection compression ignition engine. Influences on auto ignition and combustion behaviors of various ambient temperature from 600 to 800 K and different biodiesel fractions were studied in a rapid compression expansion machine (RCEM) at compression ratio of 11. Increased biodiesel fraction caused the ignition delay time to shorten. This is because the biodiesel has a better flammability than gasoline. The experimental results are compared with those from numerical simulation using CHEMKIN-PRO and surrogate fuels, and they are in good agreement. (C) 2016 The Authors. Published by Elsevier Ltd.