Studies on optimum fins number in PCM-based heat sinks

Phase change material (PCM) based heat sink is an appropriate technique for electronic devices cooling. PCM-based heat sinks have a low overall thermal conductivity. Using vertical fins is a brilliant approach to tackle low thermal conductivity issue. The aim of this study is to present a correlation to estimate the optimum number of fins and optimum PCM volume fraction in a PCM-based heat sink. The objective function is defined as the longest safe operating time of the device prior to reach the critical temperature. The independent parameters are heat sink height, fin thickness and heat flux. Around 900 various geometries of heat sink in the height range of 10-30 mm, fin thickness range of 0.2-0.5 mm were studied for two different input heat fluxes of 5000 and 10000 W/m(2) to find the optimal number of fins. The analysis of variance was used to investigate the regression model reasonableness and find the main and interaction effects among the input parameters. The Results reveal that the optimal number of fins decreases by increasing the fin thickness. The increase in heat sink height results in higher optimal fin spacing, which consequently decreases the optimal number of fins. For a heat sink with constant width, a larger number of fins is required to prevent interfering with thermal performance, as the heat flux increases. The proposed correlations cover the Rayleigh number range of 3.3 x 10(6) <= Ra <= 5.4 x 10(8). (C) 2019 Elsevier Ltd. All rights reserved.