Modelling the solidification process of supercooled phase change materials with high Prandtl number using the total enthalpy-based lattice Boltzmann method

Modelling the supercooled solidification of PCMs is challenging due to the multi-value problem particularly for high Prandtl numbers (Pr). An improved total enthalpy-based lattice Boltzmann method is applied to simulate the solidification process of supercooled sodium acetate trihydrate (SAT, Pr = 40) in a vertical cylindrical container triggered by local cooling. The evolutions of the SAT temperature profile, solid fraction and particularly the solidification front are monitored, and the effects of the cold source temperature (Tcool) and the cooling area (l x l) are analyzed. The results show that the presented method accurately characterizes the supercooled solidification; decreasing Tcool from-5.5 degrees C to-7 degrees C reduces the induction time by 95.7 % and the discharging period by 11.1 %; increasing cooling areal x l from 2 x 2 cm2 to 8 x 8 cm2 also shortens the induction time from 11 s to 7 s and the discharging period by up to 500 s. The larger cooling areal x l accelerates the movement of the solidification front and also has a significant impact on its morphology. The present model proposes an alternative numerical method for predicting the discharging performance of the supercooled high-Pr PCMs inside containers.