Impact of aspect ratio and thermophysical properties on heat transfer behavior in spiral microchannel

Abstract

The heat transfer characteristics in spiral microchannels are studied numerically in this present work. Impact of aspect ratios (α = 0.5–2) and Reynolds number (Re = 15–1200) on Poiseuille number (f.Re) and Nusselt number (Nu) is investigated with the help of local flow patterns. Three-dimensional numerical simulations are performed by varying the Reynolds number at the inlet of spiral microchannel supplied with constant heat flux boundary condition and considering thermo-physical property variation. It is observed that, in the Dean flow regime, the Poiseuille number and Nusselt number vary directly with Reynolds number whereas they vary inversely with aspect ratio. However, some non-monotonous variation of Nusselt number is reported in spiral microchannel having aspect ratio equal to unity. This behavior has been explained with the help of merging and splitting of vortices along the flow direction. Interestingly, all the aspect ratio microchannels exhibit comparatively same thermal performance factor but different temperature homogeneity. These findings have direct implication in the design of micro heat sinks and microreactors employing spiral microchannels.