The research of shutdown temperature drop rule in heated oil pipeline was the primary condition to ensure the safe restarts of the pipeline. According to the characteristics of service environments of submarine oil pipeline, based on the theory of porous media heat transfer, the submarine soil moistureheat coupling equation was established. Regularity of change of oil temperature was simulated in submarine pipeline during shutdown with time by software．The factors of effecting，such as thermal insulation layer, temperature of seepage flow and speed of seepage flow and so on，were analyzed，which decided a rational time for shutdown and provided a theoretical guidance for safe submarine oil pipeline startup．

Based on finite volume method, a threedimensional calculation model of a wavy fin exchanger was built up for fluidflow and heattransfer study, and using CFD software, numerical simulation were carried out for fluid flow and heat transfer inside the heat exchanger of 6 different inclination angles under conditions of different air velocities. The variations of the temperature field, pressure field and velocity field in the channels were analyzed, and the variations of heat transfer, pressure drop and outlet temperature with the inlet velocity were obtained. The results show that the heat transfer, pressure drop and outlet temperature increases with the increase of the corrugation inclination; the heat transfer increases while the pressure drop and outlet temperature decreases with the rising flow velocity;obvious nonuniformity of flow and heat transfer exists between the fins,resulting in obvious heat transfer "dead zone" at the leeward side of the heat transfer tube.