A comparative study of viscous dissipation effect on entropy generation in single-phase liquid flow in microchannels

Abstract

The influence of viscous dissipation on entropy generation in fully developed forced convection for single-phase liquid flow in a circular microchannel under imposed uniform wall heat flux has been studied. In the first-law analysis, closed form solutions of the radial temperature profiles for the models with and without viscous dissipation term in the energy equation are obtained. In the second-law analysis, for different Brinkman number and dimensionless heat flux, the variations of dimensionless entropy generation and Bejan number as a function of the radial distance are investigated. The two models are compared by analyzing their relative deviations in dimensionless entropy generation and Bejan number. Comparisons are also performed for average dimensionless entropy generation and average Bejan number. Contribution of heat transfer irreversibility and fluid friction irreversibility to the deviations is analyzed and discussed. It is found that, under certain conditions, the effect of viscous dissipation on entropy generation in microchannel is significant and should not be neglected.