Development of correlation for melting time of phase change material in latent heat storage unit

In view of the rapid growth in global energy demand and depletion of conventional sources of energy, developing efficient and inexpensive energy storage is as important a field of research as developing new source of energy. Latent Heat Storage Unit (LHSU) employing Phase Change Materials (PCMs) is one of the most effective ways for thermal energy storage. The melting/freezing time of the encapsulated PCM is one of the essential parameters for determining the size and the shape of the container. However, due to non linear nature of temperature distribution of PCM and moving solid liquid interface, a generalized approximate solution of melting time of PCM is not possible. In the present research work an attempt is made to propose a correlation for total melting time required for the PCM packed in shell and tube type LHSU. Several trials on shell and tube type LHSU with different PCMs I.e. paraffin wax and stearic acid are carried out at different mass flow rates and fluid inlet temperature considering solar water heater application. From the experimental data, a correlation for melting time of PCM based on Reynolds number, Stefan number and temperature constant is proposed. This can be useful for determining the shape and size of LHSU. (C) 2015 The Authors. Published by Elsevier Ltd.