The impact of heterogeneous pin based micro-structures on flow dynamics and heat transfer in micro-scale heat exchangers

Abstract

Overheating is the most important limiting factor for efficient performance of miniature electronic devices. Porous microfluidic systems are recently introduced as a promising remedy to this problem. Increasing the heat removal using porous microfluidic systems comes at the cost of increased hydrodynamic friction in the device. In this study, we focus on the flow dynamics in microchannels with embedded heterogeneous porous structures to identify effective parameters to make porous patterns with less friction while maintaining a high heat transfer rate. The heterogeneous porous structures are defined using columns of pins with different pin sizes. We analyze the flow dynamics and heat transfer using quantitative and qualitative flow patterns, energy distribution, and particle tracking analyses. We find that the structure of the porous medium plays an important role in the hydrodynamic flow distribution and as a result on the overall heat transfer characteristics. While higher heat transfer rates in homogeneous porous media are proportional to higher friction, heterogeneous porous media revealed more complex flow dynamics. It was shown that an optimized distribution of the pins in the microchannel can lead to the systems where the heat transfer increases and, at the same time, the frictions decrease. We show that the columns at either end of the porous medium are the ones that affect flow dynamics and heat transfer the most.