Pore scale simulation for melting of composite phase change materials considering interfacial thermal resistance

Abstract

• Implicit-enthalpy-based LBM with interfacial thermal resistance is proposed. • Porous structure is reconstructed by randomly generation-growth method. • The effective thermal conductivity of composite PCMs is evaluated. • The effect of natural convection, porosity and interface on melting are analyzed. The convective melting process and thermal performance of phase change materials (PCMs) incorporating porous skeleton in the one-side-heated rectangular cavity are investigated numerically in this work. A pore-scale lattice Boltzmann method (LBM) with implicit scheme is developed to explore the solid–liquid phase change process. The interfacial thermal resistance between the skeleton and PCMs is considered by interfacial conditions treatment. The random porous microstructure is generated by quartet structure generation set (QSGS) which is used to compute effective thermal conductivity in LBM. The validations of the current model are employed by the two-phase series conduction model and previous numerical results. The effects of porous structure, skeleton material, and thermal interfacial conditions on heat transfer characteristics are systematically investigated. The computational results show that the melting rate and effective thermal conductivity increase with the reducing porosity and the high thermal conductivity of the skeleton material accelerate the melting process. In addition, the consideration of interactions in the LBM leads to a significant difference. When the thermal interfacial resistance is set to be 1 × 10 −4 m 2 W/K, the temperature drop is very large in two-phase conduction, the melting rate decreases remarkably in the phase change process. The present simulation is also suitable for optimizing the porous structure to prepare various composite PCM in the thermal energy storage field.