MATHEMATICAL MODELLING OF LOW GRADE THERMAL ENERGY STORAGE USING AN ENCAPSULATED LIQUID MEDIUM

In the present study, we report the results obtained from numerical simulations of low grade heat storage. Four different fluid encapsulated materials were tested in four design types for their suitability as a small scale, low temperature thermal energy storage (TES). This was done by analysing and evaluating the maximum temperature reached per sphere for three different positions inside the tank, which correspond to the top right, centre and bottom right sphere. The influences of the material properties and the inlet/outlet tank designs were analysed and evaluated based on the results. The heat transfer fluid (HTF) was water and the storage materials selected were water, glycerol, MDM and MD3M. These were heated sensibly from an ambient temperature of 20°C to 90°C. The analysis shows that the materials with the highest relevant properties do not in fact charge the tank the fastest. Furthermore, the design of the inlet greatly affects the heating dynamics of the system, whereas changing the outlet design marginally affects the results.