Experimental Investigation and Prediction of Density and Viscosity of GTL, GTL–Biodiesel, and GTL–Diesel Blends As a Function of Temperature

Abstract

The purpose of this study is to experimentally investigate the densities and viscosities of gas-to-liquid (GTL)–biodiesel and GTL–diesel blends for various fuel temperatures and blending ratios. The biodiesel used in this study was derived from soybean oil, and was added to GTL from 20% to 100% by volumetric ratio. In the case of the GTL–diesel blend, diesel was added at 30% and 70% by volumetric ratio. Based on the experimental results, the empirical correlations for densities and viscosities were derived for variations in fuel temperatures and blending ratios. The densities of GTL–biodiesel and GTL–diesel blends decreased linearly with increasing fuel temperature and GTL is insensitive to temperature change compared to biodiesel and diesel. The dynamic and kinematic viscosities of GTL–biodiesel and GTL–diesel blends decreased exponentially with increasing fuel temperatures. As the fuel temperatures increased, the rate of change in viscosities for the temperature change significantly decreased. The increase of biodiesel and diesel in GTL blended fuels caused an increase in density. At a given temperature, the rates of density increase in the GTL–biodiesel and GTL–diesel blends showed similar values. The rates of density increase caused by biodiesel blending were higher than that caused by diesel blending due to the high density of biodiesel. With increased fuel temperature, the variations in viscosity from the blending of biodiesel or diesel with GTL decreased. In terms of the interdependence of density and kinematic viscosity, the density and the kinematic viscosity were positively correlated. At the same density conditions, an increase in biodiesel or diesel content in GTL blended fuels caused a decrease in the kinematic viscosity of the blended fuels.