Heat transfer enhancement by electroconvection resulting from an injected space charge between parallel plates

Abstract

An examination of heat transfer between two parallel plates due to electroconvection is presented. Unipolar ion injection can be brought about at either the upper or lower electrode with heating of the liquid layer from above or below (stable or unstable stratification). The four possible configurations are treated separately. For the transitory regime, an analysis is carried out from which it is possible to calculate the thermal Nusselt number by considering an analogy between the experiment and an electric circuit of a resistance and capacitor in parallel. The values thus approximated, showing increases of up to an order of magnitude in the Nusselt number show very good agreement with the steady-state data. It is thus demonstrated that the electrical effects dominate totally over buoyancy effects for all cases considered. A short analysis of the steady state yields the relevant parameters governing the heat transfer : Id 3 for the fully turbulent flow and IVd 3 in non-turbulent conditions.