Design of PCM Thermal Storage Systems Using the Effectiveness-NTU Method
Abstract
Thermal storage systems with phase change materials are predominantly designed through numerical modelling. This can be a time consuming process. An alternative simplified method is being proposed for the design of these phase change thermal storage systems. The method is based on the effectiveness-Number of Transfer Units (ε-NTU) technique. A mathematical model has been developed using the ε-NTU technique for a cylindrical tank filled with phase change material (PCM), with heat transfer fluid flowing through tubes inside the tank. Experiments have been carried out on a cylindrical tank filled with PCM and with one, two and four coils of tubes to validate the models. Experimental results compare well with those calculated from the model. The results show that this technique can readily be used as a design tool for sizing and optimising a thermal storage unit with phase change materials. From this study, it may be concluded that the model based on the ε-NTU technique can accurately predict the effectiveness of the thermal storage system during charging and discharging.