A Three - Dimensional Numerical Simulation of Shut - Down Heat Transfer Process in Overhead Waxy Crude Oil Pipeline

An additional specific heat capacity method and a momentum source method are used to establish a mathematical model to numerically simulate the three-dimensional heat transfer characteristics and flow characteristics of the horizontal three-dimensional overhead crude oil pipeline during the shutdown process. The temperature, velocity and gelation fields of horizontal three-dimensional overhead pipelines with different radial sections along the axial direction have similar evolution processes, although they are affected by the axial temperature drop at the shutdown front. The temperature field has experienced a layered distribution, an approximately elliptical distribution, and a concentric circle distribution in turn. The state with the main heat transfer of natural convection has a large flow velocity. The flow velocity gradually disappears with the increase of the shutdown time. The main mode of heat transfer also completely changes from the coexistence of natural convection and heat conduction to heat conduction. The gel layer first appears on the lower tube wall, and then grows upward along the pipeline wall. The final gel layer gradually changes from an oval shape to a concentric circle under the driving of heat conduction.