A Characteristic Dimensionless Time in Phase Change Problems

In this paper a comparison is made between an approximate analytical solution and the numerical finite difference solution for the one dimensional solidification of a phase change material of finite size. The analytical model is not only capable of handling materials with a fixed melting temperature but is also extended to cope with materials with a transition range. In the approximate analytical model, use is made of the well known Neumann solution for the solidification in a semi-infinite region. A characteristic dimensionless time has been derived that can be used in a simplified description of the solidification of a phase-change material. With this description the testing of latent heat storage devices can be simplified and the results can also be used in simulation programs of solar energy installations with a latent heat storage.