Numerical Analysis and Experimental Validation of Heat Transfer During Solidification of Phase Change Material in a Large Domain

Abstract

Abstract Transient solidification of phase change material (PCM) dominated by natural convection is studied in this work. Water is solidified inside an insulated tank while local temperature and liquid/solid phase distributions are studied numerically and experimentally until a steady-state is reached. During the analysis, it is noted that water solidification dominated by heat transfer mechanism of natural convection is a demanding numerical procedure due to specific properties of the water that is enhancing local heat transfer. The water solidification is studied via an interactive combination of transient three-dimensional computational fluid dynamics analysis incorporating phase change modeling and the results are validated with experimentally obtained data. Existing literature recommendations suggest that large-scale and long-term solidification processes cannot be accurately modeled with large time-steps, while the objective of this work was to develop such a model. The model is based on using temperature-dependent water properties for studying the cooling of the water and the magnitude of velocities inside the tank are derived in this manner upon reaching steady-state. Consequently, the mixing effect induced by natural convection is incorporated into the solidification and melting model with constant water properties via momentum source terms to enhance the heat transfer during the transient solidification simulations and the simulation results are compared with experimentally obtained data. Before implementing the developed method, after 100 minutes from the initiation of the cooling, the results were in disagreement by ca. 15°C, while after implementing the method the difference was reduced to ca. 1-2°C for most of the observed points, significantly improving the accuracy of the solidification model.