NUMERICAL-METHOD FOR DIRECT CONTACT MELTING IN TRANSIENT PROCESS

Most of the research on direct contact melting has been carried out on the assumption of steady state or quasi-steady state. Such a methodology, however, is difficult to apply to problems in which the boundary conditions such as the temperature of heating plate or the external force exerted on the solid PCM change abruptly with time. In this study, we show an efficient algorithm to solve the transient behavior of direct contact melting, considering the solid movement by external forces exerted on a solid body as well as that by melting. The method is based on the enthalpy method, but is especially devised to satisfy the force balance on solid phase with velocity variation. It is examined through two test problems. The first one is that the system gradually approaches the steady state after the start of melting. The result shows good agreement with that by the previous steady state approach, and it is assured that the behavior during the transient process to steady state is very reasonable in a viewpoint of a physical phenomenon. The second one deals with a rather complicated situation of a copper block above a melting temperature being cooled by ice. It was verified that the present methodology can deal with such a conjugate problem feasibly and simply.