Crude oil pipeline laid with products pipeline in the same ditch is a new technology to save investment and protect environment. In order to provide reference to construction and operation optimization, the majority of this paper investigates the thermal influential factors affecting the crude oil temperature in double pipelines system using the computational fluid dynamics methodology. A two-dimensional rectangular region including the two pipelines is selected as computational domain in this investigation. Heat transfer models are proposed to obtain the temperature field distribution and the crude oil temperature drop. The impacts of pipeline interval, crude oil temperature at the outlet of heating station, diameter of crude oil pipeline and atmosphere temperature have been reasonably captured and analyzed in details. radial fraction concentration of wax moleculars, – specific heat capacity, Jkg−1 K−1 inner diameter of oil pipe, m coefficient of molecular diffusion, m2 s−1 per unit mass of internal energy, m2 s−2 coefficient of friction resistance, – acceleration of gravity, ms−2 per unit area of wax molecular diffusion quality, kgm−2 per unit mass of enthalpy, m2 s−2 entrance lengths, m Nusselt number pressure, Pa Prandtl number per unit area of heat flux density of crude oil, Wm−2 per unit mass of radiant heat transfer rate, m2 s−3 radius, m thickness of wax deposition, m Reynolds number time, s temperature, K temperature of inner pipe wall, K temperature of soil thermostat layer, K velocity, ms−1 coordinate, m heat transfer coefficient of oil flow, Wm−2 K−1 heat transfer coefficient of air, Wm−2 K−1 coefficient of heat conductivity, Wm−1 K−1 density, kgm−3 viscous stress, Pa circumferential direction,° kinetic viscosity, Pas per unit mass of energy dissipation by viscous friction, m2 s−3 air 1, 2 or 3, represents pipe wall, insulating layer and corrosion protective covering respectively wax water soil 
Simulation analysis of thermal influential factors on crude oil temperature when double pipelines are laid in one ditch