Evaluation of Rheological and Lubrication Properties of Selected Alcohol Fuels

This article presents the results of a study on the rheological and lubricating properties of selected alcohol fuels. Methanol, ethanol, and 2-propanol are investigated, for which density, kinematic, and dynamic viscosity are determined at selected temperatures in the range of 15–60 °C. In addition, the water content of the studied fuels is determined. Based on the measurements, the coefficient of temperature change for density and the relative percentage decrease in kinematic viscosity with increasing temperature are calculated. Subsequently, regression models are built to describe the value of density and viscosity of the tested liquid alcohol fuels as a function of temperature. Next, the fuels under study are subjected to the evaluation of antiwear properties using a high-frequency reciprocating rig (HFRR). For each fuel, the corrected wear scar size WS1.4, which is a measure of lubricity, the average coefficient of friction, and the relative percentage decrease in oil FILM thickness during the conduct of the HFRR test under standardized conditions, are determined. The measurements are carried out at a standardized temperature of 25 °C in accordance with standardized methods for a time equal to 75 min. Due to the low lubricity of the tested fuels, additional tests are performed at a reduced time equal to 30 min. In this case, all fuels show a similar WS1.4 value, which ranges from 384 μm for methanol through 422 μm for 2-propanol to 426 μm for ethanol. The wear marks on the samples after the execution of the test are used to draw additional qualitative conclusions about the lubricating properties of the tested alcohols. The results obtained are summarized, and possibilities for their use in further research are provided.