Non-isothermal paraffin oil flow in the pipeline

Abstract

In this article, Non-isothermal paraffin oil flow in the pipeline with Newtonian fluid transition to viscoplastic state is investigated. Rheological properties of paraffin oil (viscosity, ultimate shear stress) are highly dependent on temperature. During hot pumping of paraffin oil through pipelines, non-isothermal flow occurs due to heat transfer to the environment. This leads to a decrease in flow temperature, an increase in viscosity, ultimate shear stress appearance, wax crystallization and solid particles deposition on the pipeline inner wall. Oil solid particles deposition reduces pipeline flow area, leads to the appearance of a "stagnant zone"with thermal insulation in the near- wall region. Oil structure changes - Newtonian property at high temperatures transits to non-Newtonian state. One-dimensional modeling of non-isothermal paraffin oil flow in the pipeline by traditional averaging of temperature and velocity over the pipe cross section does not allow explaining physics phenomenon. Therefore, in this work, a two-dimensional model of motion and heat transfer of paraffin oil is constructed. Calculated data show Newtonian fluid transition to viscoplastic state due to the heat exchange of paraffin oil with the environment. Obtained results form the basis for modeling anomalous fluid flows with heat and mass transfer and phase transition. Article content will be useful for a wide range of researchers involved in the field of hydrodynamics and heat and mass transfer.