Variable radiative property problem in phase-change inside a semitransparent medium

Phase-change heat transfer in a semitransparent medium is the focus of many engineering fields. Its essence is the transient coupled heat transfer of radiation-conduction with phase change under the condition of variable physical properties. The difficulty is to solve the variable radiative property problem, especially the problem for the variation of refractive index with space and time in phase change. This paper first investigates the problem of variable refractive index in phase change. The phase-change medium is assumed to have solid, mushy and liquid zones, and the solid/mushy and liquid/mushy interfaces are considered to be semitransparent and diffuse reflecting. Using multilayer radiative transfer models, the radiative transfer in the phase-change medium is simulated. Considering the change of refractive index distributions with phase-change time and phase states, its effects on the coupled heat transfer of phase change and radiation are examined. The results show that the effects of variation of refractive index could not be neglected in phase change inside the semitransparent medium.