THERMAL ENERGY STORAGE PROBLEMS

Abstract

The paper presents the overview of the theoretical and experimental research concerning thermal energy storage problems in the Institute of Heat Engineering.The authors examined a lot of substances which seemed to be suitable for thermal energy storage. The following thermal properties of materials have been measured: melting temperature, latent heat, specific heat vs. temperature for solid and liquid phase and global change of enthalpy for the temperature range of the storage system. Stability of thermal properties (mainly the latent heat) is also a very important property of materials from the viewpoint of thermal storage and has been checked as well. Some characteristics of charging and discharging processes of the single cylindrical vessel and the storage unit with phase change materials (PCMs) are presented in the graphic form. The short description of numerical simulation of Stefan problem (melting and solidification phenomena) will be discussed. The results of numerical calculation of 2-D and 3-D temperature fields for heating and cooling PCM for single vessel and the whole storage unit (i.e. about 60 MJ of thermal capacity) have been compared with experimental results.