Freezing and melting of water in spherical enclosures of the type used in thermal (ice) storage systems

This paper describes and evaluates the results of an experimental study aimed at the characterisation of the freezing and melting processes for water contained in spherical elements of the type often found in the beds of thermal (ice) storage systems used building air conditioning systems. The results include semi-empirical equations that allow the mass of ice within a sphere to be predicted at any time during the freezing or melting processes. It is believed that these equations will be useful in modelling the dynamic behaviour of thermal (ice) storage using spherical elements as phase change. The apparatus, method and results are described. A novel method which was used to measure the water–ice interface position during the freezing process is also described. Several interesting results were obtained from this study.