Analytical and Hybrid Solutions for Heat Transfer in Combined Electroosmotic and Pressure-Driven Flows

This paper presents solutions to heat transfer problems that occur in flow micro-channels driven by the combined effect of electroosmosis and a pressure gradient. Fully developed velocity profiles are considered, and the thermal developing region is analyzed. The solution methodology is based on the Generalized Integral Transform Technique, which leads to fully analytical solution for all presented cases. With the solution of the temperature fields, the behavior of the Nusselt number is investigated for different test-cases. The effects of the flow driving mechanisms, viscous dissipation and Joule heating, as well as axial diffusion are analyzed. The approximated solution with thin Electric Double Layers (EDL) is considered, but cases without this restriction are also analyzed. The cases including axial heat conduction are analyzed for a simplified case of purely electroosmotic-driven flow with a thin-EDL, which leads to a simple analytical solution.