Application of DieselB10 formulations with short-chain alcohols in diesel cycle engines: phase equilibrium, physicochemical and thermodynamic properties and power curves

Diesel oil is one of the main fuels applied in the transport industry. With a view to contributing to sustainable energy development, the use of mixtures containing diesel, biodiesel and alcohols is an attractive option. This research aims to develop and characterize new fuel formulations with DieselB10/Butanol/Methanol (DBM) and DieselB10/Butanol/Ethanol (DBE) using a combined approach of experimentation in diesel engines and advanced thermodynamic modeling. The formulations were determined based on equilibrium diagrams (25 °C) and submitted to density tests (ASTM D4052), kinematic and dynamic viscosities (ASTM D7042), corrosiveness to copper (ASTM D130), fluidity point (ASTM D97), cloud point (ASTM D2500), cold filter plugging point (ASTM D6371) and vapor pressure (ASTM D6378), which showed 100% compliance with National Petroleum, Natural Gas and Biofuels Agency (ANP) specifications. Next, the mixtures were used to construct diesel cycle engine power curves (ABNT – NBR ISO 1585). The miscibility curves indicated that the DBE system, which uses ethanol, has a smaller biphasic region compared to the DBM system, due to the lower polarity of ethanol. Thermodynamic models UNIQUAC (Universal Quasichemical) and NRTL (Non Random Two-Liquid) were employed, with UNIQUAC being more accurate (RMSD—Root Mean Square Deviation—of 0.34%) compared to NRTL (RMSD of 2.25%). The addition of alcohols increased the cloud point and vapor pressure while reducing viscosity and density. The formulations met ANP standards and did not present a corrosion risk. Engine tests showed that the DB formulation had lower hourly consumption and higher efficiency compared to DieselB10, with increased specific consumption due to the lower calorific value of the alcohols.