Heat transfer and flow characteristics of varying curvature wavy microchannels

Abstract

This paper compares the thermohydraulic performance of varying curvature wavy microchannels, namely elliptical-wavy and sinusoidal-wavy microchannels. The amplitude of microchannels is fixed at 0.6 mm, and wavelengths are varied from 3 mm to 8 mm. Simulations are performed for the laminar flow of water (160 ≤ Re ≤ 900) considering three-dimensional conjugate heat transfer using ANSYS Fluent version 2020R2. The computational model has been validated by performing experiments on a serpentine-wavy microchannel, a special case of the elliptical-wavy microchannel, using micro-particle image velocimetry (μ-PIV) test facility. Both Nusselt number and friction factor increase with the increase in waviness. Elliptical-wavy microchannels have superior thermohydraulic performance than sinusoidal-wavy microchannels except for the channel of highest waviness at Re = 160. A microchannel with lower entropy generation has a higher thermohydraulic performance. Further, we observe centrifugal instabilities in both sinusoidal-wavy and elliptical-wavy microchannels at higher Reynolds numbers. Centrifugal instabilities in the elliptical-wavy differ from those in the sinusoidal-wavy microchannel by the asymmetric formation of additional vortices about the horizontal midplane in the channel cross-section.