Effect of non-uniform electric fields on convective heat transfer in a colloidal fluid

The effect of radial electric fields on the convective heat transfer coefficient of a colloidal fluid (haematite in distilled water) has been studied as a function of various quantities such as time, electric field, pH value, colloidal concentration and orientation. The electroconvective heat transfer coefficient exhibits a 'timing' effect as well as an 'aging' effect. Whereas an AC field always enhances the heat transfer, a DC field produces an enhancement that is almost vertical in the vicinity of the origin. An increase in particle concentration increases the heat transfer coefficient, while a sharp rise in heat transfer coefficient is observed when the surface charge of the collidal particle is increased. Furthermore, the convective heat transfer coefficient increases when the inclination of the cylinder is changed from the horizontal to the vertical position.