Numerical Simulation Research On Heat Transfer And Fluid Flow Analysis Of ONAF Transformer’s Cooling System

The Oil-Immersed Transformer is a crucial device in electric power system due to its characteristic of low loss, good power dissipation and large capacity. To satisfy the power demand both in manufacturing and daily life, the safety and stability of transformer has become an important problem should be concerned. Running causes loss, which would increase inner temperature of transformer, affect the life expectancy and influence the running safety of the entire transformer. To avoid this safety hazard, the inner temperature of transformer should be controlled in a safe range. ONAF transformer introduced in this paper which utilizes transformer oil as a cooling medium, with the attachment of gilled radiator outside-blower available at the bottom, builds a closed circuit Cooling System associated with pipeline.In this paper we firstly introduce the theory of oil-immersed transformer and gilled radiator. Then, the numerical investigation of increasing temperature of ODFS-334000/500high voltage winding is analysed. The average temperature rise, the hot spot temperature and the hot spot temperature rise of high voltage winding were calculated by simulation and we also get the temperature field and the velocity field. And the effects of inlet velocity and load coefficient are concerned too.This paper also reviewed the gilled radiator outside the transformer. The inner temperature distribution and flow distribution are got through numerical simulation of gilled radiator. The heat transfer capability and the convective heat transfer coefficient are researched by changing fin pitch. Then, the temperature distribution and flow distribution of individual radiator inner channel is researched. The heat transfer capability is improved by changing the inner flow distribution in the cooling fin. Final model is built by multiple model simulation,so it can give suggestions for configuration improving of gilled radiator.