Analytical solution of the melting process of phase-change materials in thermal energy storage system

The phase-change interface is a non-linear mathematical problem, and the superposition principle is not suitable for the solution. At present, only a few researches contribute to the analytical solution on the phase-change problem. The advantage of the analytical solution is that it costs a few computational sources and results can be used to predict another situation with different conditions. To understand the heat-transfer character of phase-change materials (PCM), a one-dimensional physical model of the phase transition is established and the corresponding experiments are developed. Phase-change process of pure paraffin and composite PCM is analyzed with the method of the Runge-Kutta and verified by experiments. The temperature curves of the analytical solution have a consistent tendency with that of the experimental results. The temperature difference of experimental data (10.04 degrees C) is smaller in the melting process of pure paraffin, while that of analytical solution (5.18 degrees C) is smaller in the melting process of composite PCM. By comparing the experimental data and analytical solutions, it is found that natural convection dominates the melting of pure paraffin, while heat conduction dominates the melting of composite PCM.