In this study, the latent heat thermal energy storage system of the shell-and-tube type is analyzed experimentally. A novel design for the storage unit whose geometry is consistent with the melting/solidification characteristics of phase change materials (PCMs) is introduced. Three kinds of paraffin with different melting temperatures are used as PCMs. Water is used as the heat transfer fluid (HTF). At first, the thermophysical properties of the paraffins used are determined through the differential scanning calorimeter (DSC) analysis. The effects of the Reynolds number and the Stefan number on the melting and solidification behaviors are determined. It is disclosed the novel tube-in-shell storage geometry introduced in this study suggests promising results.(C) 2007 Elsevier Ltd. All rights reserved.