Lattice Boltzmann simulation of melting of a phase change material confined within a cylindrical annulus with a conductive inner wall using a body-fitted non-uniform mesh

摘要

In this paper, the lattice Boltzmann method on a body-fitted non-uniform mesh is employed to simulate the outward melting of a pure phase change material (PCM) confined in a cylindrical annulus with a conducting inner wall, forRa=104?105andSte=1. To perform the propagation step on the non-uniform mesh, the Taylor series least square method is used. After verification of the developed code against the experimental and numerical benchmark solutions, the effects of Reynolds number, radius ratiorr, wall to PCM conductivity ratioλ, dimensionless inner wall thicknesst?, and thermal boundary condition on the melting process are studied. It is concluded that the smaller radius ratios enhance the melting process. It is seen that the results of cases withλ=10andλ=100are in good agreement with each other and with the corresponding cases where the wall thickness is ignored. However, this is not the case forλ=1. Moreover, it is seen that forλ=10andλ=100, the biggert?enhances the melting process whereas, forλ=1, the reverse is true. Finally, it is figured out that the effect of applying the adiabatic conditions on the outer cylinder, instead of the constant temperature, enhances the liquid fraction in such a way that this improvement is seen to be more pronounced for the times after the melted PCM first touches the outer cylinder.