Abstract—Generated corona discharge between a sharp electrode and a grounded heated surface usually induces an ionic wind, whose momentum can be used for enhancement. The influence of the active-vortex induced by corona discharge is clearly emphasized to have access to better and illuminating understanding of the enhancement mechanism. An electrostatic blower employs a long stretched thin wire electrode, which is confined by two inclined wings. The latter bestows a longitudinal nozzle for the airstream as well as electric shield. The heat transfer coefficient can be easily increased, as compared with a Natural convection mechanism. A linear relationship is achieved between the Nusselt number and Reynolds number. Senftleben number is found useful in correlating EHD enhanced Natural convection with working fluid air. Proposed empirical correlations will become a powerful tool for designers for such devices employing EHD enhanced Natural convection. Empirical correlations for predicting the extent of electrohydrodynamic enhancement of Natural convection heat transfer from heated horizontal cylinder are skilfully presented. The said correlations are validated with the measured results from different experiments. Nusselt number enhancement is correlated in terms of electrical Rayleigh number (RaEl). RaEl is also found to account for the effect of nonuniform electric field on Natural convection. To investigate the influence of D.C. high voltage electric field on the Natural convection heat transfer of a vertical heated plate in dielectric liquid, boundary layer equations are solved. A considerably large heat transfer enhancement over a wide area is expected. The heat transfer duty of heat exchangers can be augmented by heat transfer enhancement technique. The active technique requires high voltage D.C. electric field. This paper can be used as the first guideline for the researchers in using EHD technique for Natural convection heat transfer enhancement.

Index Terms—Ionic wind, Corona discharge, EHD, Natural convection, Electric-field

Cite: Ritesh Kumar and Amit Kumar, "Enhancement of Natural Convection Heat Transfer by the Effect of High Voltage D.C. Electric Field," International Journal of Mechanical Engineering and Robotics Research, Vol. 3, No. 1, pp. 42-49, January 2014.