Experimental study of solid-liquid phase change in a spiral thermal energy storage unit

A new idea on the use of a vertical spiral heat exchanger in a latent heat thermal energy storage system is analyzed experimentally. In this context, two important subjects are addressed. The first one is the temporal behavior of a phase change medium undergoing a non-isothermal solid-liquid phase change transition during its two-side heating or cooling by a working fluid flowing in a spiral channel. The second one is the analysis of temporal thermal characteristics of the paraffin wax-air thermal energy storage unit of the Archimedes spiral geometry during its charging and discharging. The results are presented in terms of temperature changes of both media. Moreover, thermal analysis of the storage energy unit is carried out where temporal energy stored, overall charging ratio, total time of charging or discharging processes and time changes of melted and solid phases of the storage medium are estimated. (C) 1999 Elsevier Science Ltd. All rights reserved.