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SUMMARYThe present article reports on the characterization of granular phase changing composites using the T-history method. Further modifications and improvements of the method are employed to handle granular materials undergoing phase change over a temperature range. The accuracy of the T-history method is shown to be limited by the assumption of temperature-independent specific heats and the difficulty of determining the limits of solid and liquid phases. The concept of enthalpy and its relationship with temperature has been employed in the analysis to overcome these difficulties. Enthalpy-temperature and apparent heat capacity curves similar to those obtained using DSC have been developed. These characteristic curves are necessary for accurate design, modeling, and optimization of latent heat thermal energy storage systems. Experiments have been also carried out to measure the transient temperature distribution inside a cylindrical packed bed using phase changing granulates. Analysis of temperature variation along the bed shows good agreement with the measured phase change characteristics.