Thermal analysis of cylindrical heat sinks filled with phase change material for high-power transient cooling

In this study, the thermal performance of cylindrical heat sinks filled with phase change material (PCM) is investigated for high-power transient cooling. Herein, n-eicosane present in heat sink cavities is used as the PCM, whereas aluminum is used as the heat sink material. For the PCM-based cylindrical heat sink, a two-dimensional numerical model is constructed to determine the influence of various geometrical and thermal parameters, such as fin height, cavity angle, fin angle, base thickness, and power level, on the PCM melting process. All parametric simulations were performed using the heat sink unit cell by exploiting the symmetry. Results show that the PCM melting time can be increased by increasing the amount of PCM filling the cavity and increasing the mass of the heat sink material. Furthermore, dimensional analysis generalizes the obtained numerical results. The PCM melt fraction and corresponding Nusselt number are generalized in terms of a combination of the Fourier, Stefan, and Rayleigh numbers by introducing the effective heat flux to account for three-sided wall heating for the cylindrical heat sink. New correlations for predicting the PCM melt fraction and Nusselt number during the PCM melting process in cylindrical heat sinks are proposed as a function of the combination of dimensionless groups.