Considerable research has been conducted on heat transfer enhancement of phase change materials (PCMs) in thermal energy storage systems. A new concept of a heat transfer enhancement technique for a tube-in-tank phase change thermal energy storage system, dynamic melting has been investigated through computational fluid dynamics analysis. This process involves forced recirculation of melted PCM during melting generated by heat transfer fluid. Dynamic melting was found to accelerate the melting process compared to natural convection. However, significant increases in heat transfer could only be achieved when the PCM flow rate was equal to or greater than the flow rate of the heat transfer fluid. Both parallel and counter flow for the PCM and the heat transfer fluid were analysed. The method represents a promising approach to heat transfer improvement in tube-in-tank PCM systems. (C) 2014 Elsevier Ltd. All rights reserved.