Numerical study of melting-process of a non-Newtonian fluid inside a metal foam

Abstract

Non-Newtonian behavior of a Phase Change Material (PCM) inside a porous coaxial pipe is studied by utilizing the deformed mesh technique. The inner and outer pipes are subjected to the high and low temperatures of Th and Tc, while the bottom and upper surfaces are thermally insulated. The Finite Element Method (FEM), implemented in the Arbitrary Eulerian-Lagrangian (ALE) moving grid technique, is applied to solve the weakened forms of the governing equations. Stefan's condition is employed to track the solid-liquid interface of the PCM during the melting process. Grid independency test is conducted, and the verifications of the results are evaluated through comparisons with several test cases published in the literature. The simulations show that an increment of Stefan's number can significantly improve the melting rate. As the Stefan number reaches from 0.014 to 0.01, the full melting non-dimensional time declines from 1.313 to 0.937. Also, an extreme increase in the melting rate can be found while decreasing the power-law index. When the power-law index decrease from 1 to 0.6, the full melting time subsequently is reduced to 54%. Keywords: Phase Change Material (PCM), Non-Newtonian PCM, Porous medium, Arbitrary Eulerian-Lagrangian (ALE), Stefan condition