Study of Phase Change Material-Based Hybrid Heat Sink for Electronics Cooling Application

The performance of a phase change material (PCM)-based hybrid heat sink is evaluated using a transient, 3-D numerical study. PCM is used in a passive cooling method to dissipate the heat, whereas liquid flowthrough microchannels is employed as active cooling to resolidify the PCM. Passive and active cooling modes operate periodically, governed by various operating temperatures. Simulations are performed by varying aspect ratio (AR) of the microchannel (AR = 1 and 3) and fin spacing/PCM volume (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S = 1$ </tex-math></inline-formula>, 2, 4) for the range of Reynolds number (Re = 497, 995, 1492) and supplied heat flux (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q'' = 50$ </tex-math></inline-formula>, 100, 150 kW/m2). Transient variations of junction temperature, PCM liquid fraction, and energy consumption are recorded and analyzed in detail for all the cases studied. The objective is to identify the parameters leading to less active cooling time than passive cooling. The numerical results show that the frequency and amplitude of periodic temperature variation owing to passive-active–passive cooling are a function of Reynolds number, heat flux, PCM volume, and AR of microchannels. The time of active cooling and the quantity of resolidified PCM vary inversely with the Reynolds number. Furthermore, an increase in AR was observed to have a favorable effect on improving the performance of PCM-based hybrid heat sink. For the range of parameters studied in this work, it is observed that around 22%–89% less energy is consumed by a hybrid heat sink if a microchannel of AR 3 is used compared to that of 1. The quantity of PCM plays a vital role in the performance of hybrid heat sinks; therefore, a fin spacing of 1 mm works better than that of 2 and 4 mm. The proposed concept of a hybrid heat sink will help reduce the dependency on an active cooling system for miniaturized electronic devices.