Comprehensive analysis of melting and solidification of a phase change material in an annulus

A one-dimensional conduction heat transfer model has been proposed to study the melting and solidification of phase change material (PCM) inside an annulus. Here, the phase change process is divided into two main sub-processes such as melting and solidification sub-process. Subsequently, each sub-process is analyzed for various temporal regimes. The temporal regimes include completely solid, partially molten and completely molten for melting sub-process and in reverse order for solidification sub-process. Later on, the solution for temperature distribution for each temporal regime is obtained either by employing Variational formulation or using a method of quasi-steady state. The solution of each temporal regime is united to provide a closed form solution for temperature distribution for the sub-process. Present model exhibits good agreement with the existing experimental data. The results indicate that melt duration can be increased by increasing the thickness of PCM in an annulus. It is also found observed that for any thermal storage unit there exists a particular percentage of TCE-PCM distribution through which maximum melt duration can be achieved.