Entropy generation analysis of electro-osmotic flow in open-end and closed-end micro-channels

Abstract

The analysis of entropy generation mechanism is very important to optimize the second-law performance of these energy conversion devices in micro-scale. The entropy generation of electro-osmotic flow in two-dimensional open-end and closed-end micro-channels is analyzed and a rigorous mathematical model for describing electro-osmotic flow is used in this paper. The entropy generations of electro-osmotic flow due to heat conduction, viscous dissipation and Joule heating are numerically simulated. The results show that the volumetric entropy generation rates due to heat conduction and viscous dissipation exist the maximum value near the micro-channel wall, and the volumetric entropy generation rate due to Joule heating exists the maximum value at the center of the micro-channel. Because of the effect of Joule heating, the heat conduction entropy generation number and Joule heating entropy generation number increase with the applied electric field, and the entropy generation of viscous dissipation can be neglected in the open-end and closed-end electro-osmotic flow. When the temperature difference between the inlet and the top wall is larger than the temperature increment due to Joule heating, the electro-osmotic flow entropy generation due to heat conduction will take the major percent in the total entropy generation. When the temperature increment due to Joule heating is larger than the temperature difference between the inlet and the top wall, the electro-osmotic flow entropy generation due to Joule heating will take the major percent in the total entropy.