Heat Transfer in a Ferrofluid-Based Transformer: Multiphysics Modeling Using the Finite Element Method

This paper deals with a thermal-fluid-magnetic analysis based on the 3D finite element method to study the cooling efficiency inside a ferrofluid-based transformer. This cooling approach is first tested, both experimentally and numerically, on an axisymmetric coil. After cross-validation of the numerical and experimental results, a 400/230V transformer with a non-axisymmetric ferromagnetic core is modeled. The device is immersed in a steel tank filled with cobalt ferrite nanoparticles-based Midel vegetable oil. The time evolution of the temperature is recorded whether the Helmholtz magnetic force is activated or not. A decrease in the local temperature of the coil sensors by about 10ˆC is observed when the impact of the magnetic force is considered. Numerical results prove the beneficial effect of thermomagnetic convection on transformer cooling.