Experimental and numerical investigation on thermal and hydraulic performance of semiwavy minichannels using water–ethylene glycol-based nanofluids

A thermohydraulic performance investigation is performed on a minichannel heat sink with alternating straight and sinusoidal (semiwavy) profiles for different channel amplitudes (0.2, 0.4 and 0.6 mm). The study throws light on the performance of variable area minichannel heat sink combined with wall waviness. The effect of nanofluids as coolants for these channels is also investigated. Water–ethylene glycol, 0.4 and 1% alumina nanofluids are used as coolants. The performance enhancement coefficient is also evaluated. The maximum enhancement in Nusselt number is obtained for the wave amplitude of 0.6 mm and a nanofluid concentration of 1%. It is observed that the advantage of using nanofluids diminishes considerably with an increase in the relative waviness. The performance enhancement coefficient is found to be highest for the minichannel having the wave amplitude of 0.4 mm. Further increase in amplitude leads to higher pressure drop penalty. The numerical analysis reveals the occurrence of secondary vortices which is confined to the crest and trough regions of the semiwavy walls.