Entropy generation during fully-developed forced convection in parallel-plate micro-channels at high zeta-potentials

摘要

Entropy generation during laminar fully-developed flow in parallel-plate micro-channels with an imposed pressure gradient and a uniform wall heat flux has been investigated taking into consideration the effects of an EDL at the solid-fluid interfaces and viscous dissipation due to internal fluid friction. The rates of local volumetric and total entropy generation per unit channel volume due to heat transfer and viscous dissipation were calculated using analytical expressions for the velocity and temperature profiles. Comparing results from expressions using the local-temperature formulation to others using a reference-temperature formulation have shown that the latter is not accurate for low Brinkman number or small channel sizes. Effects of Brinkman number, Peclet number, channel size, and zeta-potential on the rate of entropy production are presented and discussed. Entropy production due to heat transfer reaches a maximum, while entropy production due to viscous dissipation and the ratio of pumping power to heat transfer reach a minimum within a specific range of zeta-potential. These trends were attributed to the effects of EDL on the velocity and temperature profiles.