The importance of phase change materials (PCMs) in latent heat storage (LHS) applications has attracted increasing attention in recent years. However, guidance for designers seeking to maximize efficiency remains limited. To analyse the behaviour of phase change materials under controlled conditions and to study the effects of parameters such as storage device (tank) geometry and material thermophysical properties on phase transition processes, three sets of simulations testing different PCMs were conducted in the present study. Each PCM occupies the storage device characterized by an aspect ratio \(\text{AR}\) , a volume \(V\) , and a solid wall thickness \(e\) . The first series of simulations, using the three different PCMs: paraffin wax, lauric acid (LA), and n-eicosane, was conducted to study the thermal behaviour of the PCMs during melting and solidification and to calculate the energy stored and released by these PCMs during melting and solidification, respectively. The second series of simulations, using paraffin wax as PCM, was performed to examine the effect of storage tank geometry (first by increasing the tank aspect ratio while keeping its volume constant; then by increasing the tank wall thickness) on the PCM melting and solidification processes. Finally, the last series of simulations, using a family of paraffin wax-based phase change materials, aimed to evaluate the effects of their thermophysical properties on melting and solidification performance parameters. In particular, the focus was on process duration and stored energies, including sensible, latent, and total energies. These evaluations provide insight into how material characteristics influence their effectiveness in thermal management applications. For the first series of simulations, the results indicate that the melting process is faster than the solidification process for all PCMs studied by about 72.95, 82.73, and 93.88% for paraffin wax, lauric acid, and n-eicosane, respectively. In particular, paraffin has a longer melting time by about 42.04 and 152.15% and a shorter solidification time by about 9.28 and 43% compared to the melting times of lauric acid and n-eicosane, respectively. As a result, n-eicosane has the fastest melting and the slowest solidification. In addition, n-eicosane has a higher energy storage capacity than paraffin wax and lauric acid. Indeed, the stored energies (per unit mass) of n-eicosane, paraffin wax and lauric acid are, respectively, 377, 300.5, and 321 kJ kg−1. For the second series of simulations, the findings show that increasing the tank’s aspect ratio by a percentage (e.g. 44%) decreases the melting and solidification times of paraffin wax by about 7.63 and 25.94%, respectively. Furthermore, it was found that accounting for the storage tank thickness affects the phase change process. Indeed, an increase in the thickness from the case of a tank with negligible thickness 0 mm (often considered case) to 5 mm leads to an increase in the melting and solidification times of paraffin wax by about 182.5 and 30.19%, respectively. This highlights the importance of the thickness of the solid walls of the material storage tank on its phase change processes. Finally, regarding the effect of PCM properties on phase change processes which was addressed in the last series of simulations, the results show that (i) increasing the thermal conductivity of PCM by 0.1 W m−1K−1 leads to a decrease in the melting time and solidification time by 28.73 and 26.28%, respectively, without influencing the amount of stored energy, (ii) increasing the specific heat of PCM by 0.21 \({\text{kJ kg}}^{ - 1} {\text{K}}^{ - 1}\) , increasing the latent heat of fusion of PCM by 96.73 kJ kg−1, and increasing the density of PCM by 77 kg m−3 lead to increases in the melting time by about 2.47, 25.79, and 3.2%, respectively, and to increases in the solidification time by about 3.2, 46.72, and 8.54%, respectively. These increases in melting time result in increases in the total energy stored in the PCM of approximately 4.6, 32, and 10%, respectively, and (iii) increasing the melting temperature of PCM by 6.46% leads to increase the melting time by 83.39% and decreasing the solidification time by 76.67%, while the amount of the energy stored has not affected. This contribution (study) fills a significant gap in the design of energy storage systems: the lack of clear and relevant guidelines regarding the interaction between the geometry of the storage tank and the storage material. It offers a useful tool that facilitates the development of more efficient systems, both in terms of storage capacity and charging time reduction, for practical applications.
