Numerical assessment of the multi-phase nanofluid flow inside a microchannel during the melting and solidification of PCM in the thermal management of a heatsink

Abstract

This article presents a numerical simulation of a heatsink with a large number of square pin-fins using the finite element method. A nanofluid passes helical microchannel that is placed inside the heatsink. The two-phase mixture method is employed to simulate the nanofluid flow. The space between the pin-fins and the microchannel in the heatsink is filled with phase change material (PCM). The values ​​of the heatsink temperature (T-HK), including the maximum and average temperature, the temperature of the nanofluid (T-NF) exiting the heatsink, the molten PCM fraction, and the heat transfer coefficient (HTC) are estimated by changing the Reynolds number (Re) ranging from 100 to 500 and the volume fraction of nanoparticles (φ) varying from 0 to 3% up to 500 s. The results demonstrate that an increment in the Re reduces the T-NF exiting the heatsink significantly; however, enhancing the amount of φ decreases it slightly. In 500 s and 250 s, an enhancement in the Re from 100 to 500 intensifies the maximum T-HK by 17.28 and 9.92 °C, respectively. At Re = 100, 200, and 300, the PCM melting process starts in approximately 150, 200, and 250 s, respectively.