Alcohol-diesel fuel blends and their effect in performance and exhaust emissions

Abstract

The growing demand of fossil fuel and the rising of its price strengthen the incessant search for energy alternatives. The use of alcohol-diesel fuel blends in diesel engines has recently received interest as an alternative fuel for use in spark ignition (SI) engine. However, little research concerning diesel fuel has been found. Moreover, alcohols can improve the combustion phase due to an increase of the oxygen content and reduce exhaust emissions as soot and particulate matter, besides knock. The most used alcohols in blends with diesel fuel are methanol and ethanol, butanol added recently. In contrast, there are very few studies about propanol and pentanol blended with diesel fuel, although engine results are remarkable. Some of them could be even produced via biorefinery, thus being better to the environment than the petroleum-based fuels. Nevertheless, the main challenge is to overcome disadvantages of alcohols including low lubricity, difficulty of vaporization and high auto-ignition temperature and definitely, their well-know immiscible problem with diesel fuel being required co-solvents or emulsifiers. Besides, these additives are used to enhance the properties of the fuel, like the increase of the cetane number or the production of a stable blend.