A phase change material-based constructal design finned heat sink: An evolutionary design for thermal management

Abstract

This paper explores the design evolution of constructal law in the form of constructal structures with phase change material (PCM) for the thermal management of advanced miniaturized electronics devices. A novel tree-shaped constructal design structural fin heat sink is designed of varying volume fraction and fin height. The transient temporal temperature distribution, phase-change transformation phenomenon, and conjugate heat transfer effects are attributed numerically by integrating a PCM filled tree-shaped structural finned heat sink. Different volume fractions (0%, 10%, and 20%) and fin heights (0, 10, 15, and 20 mm) of a tree-shaped structural finned heat sink are investigated by interspersing the RT-35HC (selected as a PCM) at constant input heat densities. The enhancement in heat transfer, latent-heating phase, operational time, and melting phenomenon of a PCM-based constructal design finned heat sink are evaluated with a baseline heat sink having no extended fins. A comprehensive parametric investigation is carried out of all PCM-based tree-shaped structural finned heat sink cases by evaluating different qualitative and quantitative performance metrics. In addition to that, the dimensional numbers, critical set point temperature and time are evaluated to explore the passive cooling of novel constructal designed PCM-based heat sinks. Results revealed that the rate of heat transfer mainly depends on the height of tree-shaped structural fins and the number of branches or twigs for a constant volume fraction. The addition of extended surface structure of tree-shaped material is significantly reduced the average heat sink temperature by ≈8% compared to the absence of an extended surface structure filled with PCM. The operational time is an extended by more than 1% with a 20% volume fraction compared to a 10%. Increasing the fin height from 0 mm to 20 mm, a higher time is obtained to reach a certain set point temperature, regardless of the volume fraction of fins. The Nusselt number results attribute a more dominant natural convection current of PCM melt front during melting phenomenon of PCM inside the heat sink. Solid drops of unmelted PCM are formed and Rayleigh–Bénard convection phenomenon of PCM melting is observed. The findings demonstrate that the optimum fin height and volume fraction of 20 mm and 10%, respectively, are recommended to achieve an efficient passive cooling thermal performance of advanced miniaturized electronic devices by employing a PCM-based tree-shaped constructal design heat sink.