The rheological model of biodiesels at elevated pressures and temperatures

Abstract

In the present study, an approximation is used to study viscosity as a function of pressure at different temperatures. The correlation so obtained is applied to study the viscosity of biodiesels extracted from soybean, Vistive soybean, canola, used canola, coconut and rapeseed. The computed values of viscosity from the proposed model were found to be in good agreement with experimental data throughout the range of pressure and temperature studied. The maximum average absolute relative deviation (AARD%) and mean AARD% are found to be 0.52 and 0.20, respectively, over the entire range of pressure (0.1–140 MPa) and temperature (283.15–373.15 K) for all biodiesels except rapeseed biodiesel, for which the values are 1.1 and 0.62, respectively. Furthermore, this work includes the very first investigation conducted so far on the variation of the pressure–viscosity coefficient (PVC) with pressure at different temperatures for biodiesels. The variation in PVC with the temperature is more sensitive at elevated pressures as compared to atmospheric pressure whereas the variation in PVC with pressure is more sensitive at elevated temperatures as compared to room temperature.