Fully Coupled Finite Element Analysis for Cooling Effects of Dielectric Liquid Due to Ionic Dissociation Stressed by Electric Field

A fully coupled Finite Element Analysis (FEA) technique was developed and tested to validate the cooling effects of a dielectric liquid stressed by an electric field, resulting in the ionic dissociation phenomenon. Recently, electrohydrodynamics (EHD) techniques have been applied widely to enhance the cooling performance of electromagnetic systems by introducing gaseous or liquid media. The main advantage of EHD cooling is non-contact and low-noise resulting from smart control using an electric field. In addition, in some cases, the flow can be achieved using only a main electric field source not an extra one. The driving sources in EHD flow are ionization in the breakdown region and ionic dissociation in the sub-breakdown region. This study focused on dielectric liquid flow driven by the ionic dissociation phenomena, resulting in a cooling effect of the heat source. To build on this EHD phenomenon, fully coupled FEA, which consisted of the Poisson´s equation for an electric field, Nernst-Planck equations for ions, and the Navier-Stokes equation for incompressible fluidic flow, was performed. To confirm the cooling effects, the developed velocities of fluidic flow were tested with the different applied voltages. In the sub-breakdown region, the effective velocity was approximately 2 m/s in the tip-sphere electrodes and a temperature drop of approximately 40^°C was obtained in a numerical analysis model with a fluidic velocity of 1.96 m/s from the inlet.