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 10 K is observed when the impact of the magnetic force is considered. Numerical results prove the beneficial effect of thermomagnetic convection on transformer cooling.