Numerical investigation of electro-thermo-convection and heat transfer enhancement in a square enclosure with various electrode arrangements

Abstract

The dielectric fluid was normally used to electrically shield high-voltage applications. However, recent studies on the electrohydrodynamic technique using the dielectric fluid were attentively conducted to obtain heat transfer enhancement in keeping with its electrical-insulating feature. This study numerically investigates the electro-thermo-convection in a two-dimensional square enclosure with hot and cold vertical walls. The heat transfer rate in the free convection inside the enclosure can be significantly improved by the injection of space charges and working of the Coulomb force. In this study, we tested several electrode arrangements, including alternately arranged electrode pairs on walls, under the intense charge injection condition. Consequently, the vertical arrangements of the electrode pairs demonstrate a higher heat transfer rate than the horizontal arrangements. The heat transfer coefficient of the vertical electrode pairs at a Rayleigh number of 5000 and an electric Rayleigh number of 200 is larger than three times that of the horizontal electrode pairs. Using fluid with a Prandtl number of 10, the results of the stream lines, isotherms, and space charge distributions are summarized herein for various thermal and electrical buoyant conditions.