The aim of this study was to explore the heat transfer behavior between convection and conduction in the thick wall crude oil pipeline with laminar unsteady state flow using integration of developed computational fluid dynamics model and statistical experimental design. The governing equations were employed to investigate the effects of wall thickness, wall thermal conductivity, surrounding heat transfer coefficient and ambient temperature on transport profile using statistical experimental design and to locate an origin point where wax precipitate in the pipeline (wax appearance distance) by using response surface methodology (RSM). A good agreement between the model and literature experimental data suggests that the proposed numerical scheme is suitable for simulating the transport profile in pipeline and predicting the phenomena for any other conditions. From the statistical analysis, it was found that, surrounding heat transfer coefficient and ambient temperature were the major effect parameters on the wax appearance distance. wall thickness/coded factor of wall thickness (−) pipe thermal conductivity/coded factor of pipe thermal conductivity (−) surrounding heat transfer coefficient/coded factor of surrounding heat transfer coefficient (−) ambient temperature/coded factor of ambient temperature (−) pipe diameter (m) heat transfer coefficient (kW/m2 °C) inner wall heat transfer coefficient (kW/m2 °C) outer wall heat transfer coefficient (kW/m2 °C) thermal conductivity (kW/m°C) pipe length (m) inner wall radius (m) outer wall radius (m) heat resistance (m2 °C/kW) source term time (s) temperature (°C) x-velocity (m/s) y-velocity (m/s) x-direction wall thickness (m) y-direction wax appearance distance (m) dependent variable density (kg/m3) diffusion coefficient ambient fluid/crude oil 
Integration of computational fluid dynamics simulation and statistical factorial experimental design of thick-wall crude oil pipeline with heat loss