Experimental assessment of some key physicochemical properties of diesel-biodiesel-ethanol (DBE) blends for use in compression ignition engines

Abstract

In order to reduce high import costs, and to comply with environmental standards, sustainable policies led to partially replace diesel fuel by biodiesel. However, other technologies, such as diesel-biodiesel-ethanol (DBE) mixtures, are being investigated. Blends of diesel B15 fuel (15 vol% of biodiesel in fossil fuel), with up to 2.0 vol% of this original additive, were investigated for anhydrous ethanol content ranging from 0 to 100 vol%. The density, the kinematic viscosity, the flash point, the cold filter plugging point (CFPP), the corrosiveness to copper, the cetane number, the lubricity, the contact angle and the surface tension were assessed over a large range of ethanol content. The most restrictive property was the flash point (up to 5 vol% of ethanol can be added to respect the Brazilian specification for diesel B7 fuel), followed by the cetane number (maximum ethanol content of 10 vol%). The limit rose to 40 vol% of ethanol when kinematic viscosity and density were considered. All tested blends (up to 20 vol% of alcohol) respected the Brazilian legislation in terms of lubricity. Considering CFPP, the maximum ethanol content varied from 60 to 100 vol%, depending on the region and period of the year. Corrosiveness did not provide any limitation of ethanol proportion. The sample with 1.0 vol% of additive always presented intermediate behaviour within experimental uncertainties to that observed for blends with 0.0 and 2.0 vol% of additive. The impact of the stability additive on the properties was reduced, but they lead to a null or small improvement of the investigated properties, mainly lubricity, contact angle, cetane number and viscosity, with exception of surface tension. Blends with additive at a concentration of 1.0 vol% with up to 20 vol% of anhydrous ethanol can be used in current diesel engine.