Measurements and Predictive Models for the Viscosity of Coal-Based Kerosene at Temperatures up to 673 K and Pressures up to 40 MPa

Abstract

A high-temperature and high-pressure dual-capillary viscometer was developed to measure the dynamic viscosity of liquid and supercritical coal-based kerosene in the temperature range of 299.6–678.8 K and pressure range of 0.3–40.4 MPa. The extended relative uncertainty of the measurement results ranged from 0.8–5% (confidence factor k = 2). Using the differential of the pressure drop across the capillary with flow rate in the viscosity derivation, rather than the pressure drop directly, gave better experimental precision. The measurement accuracy was validated using cyclohexane and toluene as standard fluids; the absolute average deviations (AADs) were 1.7% for cyclohexane at 0.3–20.0 MPa and 321.8–576.6 K and 2.0% for toluene at 0.3–40.6 MPa and 285.3–315.8 K. The effects of temperature and pressure on the viscosity of coal-based kerosene were investigated using four parameters: isobaric viscosity change rate, viscosity-temperature coefficient, isothermal viscosity change rate, and viscosity-pressure coefficient. It was found that the viscosity-temperature coefficient curves of coal-based kerosene intersect each other at different pressures, which are of great significance for the establishment of viscosity predictive models. Based on the characteristics of the kerosene η–T curve, we proposed a new modified Arrhenius–Andrade model and introduce the pressure term into the model. Compared with the modified VFT model and 10-parameter nonlinear surface model, the modified Arrhenius–Andrade model best fitted the experimental data with AAD of 1.6%.