Fixed-grid numerical modeling of melting and solidification using variable thermo-physical properties - Application to the melting of n-Octadecane inside a spherical capsule

摘要

A fixed-grid enthalpy model for unstructured meshes and explicit time integration schemes (Galione et al., 2014) is here extended for taking into account the change in density and other thermo-physical properties with the temperature and phase. Thermal expansion and contraction associated to the phase change are taken into account in the conservation equations, and different strategies for the numerical treatment of the energy equation are discussed in detail. Further modifications to the original model are also presented.; The proposed model is used for simulating a case of melting of n-Octadecane inside a spherical capsule. Two and three-dimensional simulations are performed using constant and variable properties. The effect of adopting two different numerical schemes for the convective term of the energy equation is evaluated. A comprehensive examination of the thermo-physical properties is performed, and the different values and correlations used are here presented and criticized. Differences in the flow patterns are encountered between two and three-dimensional simulations. The effects of considering constant or variable properties are discussed. Two different thermal boundary conditions are tested and the results are compared against experimental data obtained from the literature.