Comparative study on natural convection melting in square cavity using lattice Boltzmann method

The phase change process is of significant importance in the application of phase change material (PCM). In this paper, the natural convection melting in a square cavity was investigated and the enthalpy-based lattice Boltzmann model (TLBM) combined with the pseudo-potential LB model was developed to trace the solid-liquid interface. Four cases with different boundary conditions were calculated and the corresponding temperature contours, velocity vectors and average liquid fraction at various time were compared. Results show that TLBM has good accuracy in simulating the solid-liquid phase transition process. Variation in boundary conditions has appreciable impact on the natural convection process and melting behavior. Comparing model.1 (single heating wall) with model.2 (double adjacent heating walls with cold wall), the maximum liquid fraction is increased 16.7% in model.2 and the additional top heating wall acts to accelerate the average melting rate by 16.7%. The comparison between model.3 (double opposite heating walls) and model.4 (double adjacent heating walls without cold wall) shows that the natural convection heat transfer is intensive in model.3 and resulting in a 280% faster melting rate than that in model.4. Comparing the melting rate between the model.5 (all heating walls) and model.3, the increase of 54% due to the more heating walls in model.5 is observed.