Characteristics of entropy generation and heat transfer in a microchannel with fan-shaped reentrant cavities and internal ribs

Abstract

Three-dimensional laminar fluid flow and heat transfer in a micro heat sink with cavities and internal ribs are investigated using numerical methods. Moreover, according to the second law of thermodynamics, the model of entropy generation is also established for variable cross section of the microchannel. The simulation encompasses Reynolds number of 198–600, relative cavity height e1/Dh values of 0–0.65, relative rib height e2/Dh range of 0–0.2167. The results show that the effect of relative rib height on entropy generation is significant, while the relative cavity height has little effect on it. The combined effect of cavities and ribs in the microchannel has better performance of heat transfer than the smooth microchannel under similar conditions. Extensive simulations are conducted to collect data on the characteristics of heat transfer and fluid flow in a micro heat sink with cavities and internal ribs. Using these data, correlations for Nusselt number and friction factor in terms of Reynolds number and the geometry of cavity and rib have been developed.