Hydrothermal and Second Law Analyses of Fluid Flow in Converging-Diverging (Hourglass) Microchannel

Abstract

A three-dimensional numerical investigation is carried out to understand the mechanism of hydrothermal performance and second law analysis for a flow through converging-diverging (hourglass) microchannel. The fluid flow and convective heat transfer characteristics are investigated as a function of convergence-divergence angle, width ratio (ratio of bigger width to smaller width), and Reynolds number. The present study uses various parameters such as performance evaluation index, entropy generation, Bejan number, and augmented entropy generation number to examine the hydrothermal and thermodynamic performance characteristics of an hourglass microchannel. The parametric analysis reveals that the Nusselt number increases with an increase in convergence-divergence angle; however, it decreases with an increase in width ratio. Increasing the convergence-divergence angle effectively reduces the overall temperature gradient, whereas the width ratio has an opposite effect. The results also indicate that the hourglass microchannel shows better hydrothermal and thermodynamic performance than the uniform microchannel. For a given range of parameters, the maximum value of the performance evaluation index is 1.34, and the maximum reduction in entropy generation is 28% relative to a uniform microchannel. The findings obtained in this study may serve as a valuable roadmap for designing an hourglass microchannel in diverse heat transfer applications.