The Latent heat storage technology is being used worldwide to bridge the gap between supply and demand of energy. The material store energy during the charging process (melting) and releases energy during the discharging process (solidification). In spite of having various advantages such as high storage energy density, it suffers from the fact that most Phase Change Materials (PCMs) commonly used have a very low thermal conductivity, hence, very slow charging /discharging times. In the current work, a shell and tube type heat exchanger with phase change material on the shell side and heat transfer fluid on the tube side are considered. The effect of flow rate and inlet temperature of heat transfer fluid on melting and solidification times are investigated with single and double pass (counter and parallel) arrangements of Heat Transfer Fluid (HTF). The major difficulty encountered in the melting of the PCM is the accumulation of solid (unmelted) part at the bottom during the charging process, while the liquid part remains at the top during the discharging process, which decreases the efficiency of the system to quite a great extent. In this study, an attempt has been made to improve the efficiency of the system by considering two configurations (double and triple tube) of the shell and tube heat exchanger and it is found that the latter case has better performance.

The space heating in residential buildings in winter accounts for a considerable amount of conventional energy. Therefore, improving the performance of space heating systems with the inclusion of renewable energy sources like solar becomes crucial in order to have better occupant’s comfort while reducing energy use. Phase change material (PCM) is one of the best solutions for renewable energy, especially solar, which is intermittently available. PCM stores energy when surplus energy is available and delivers whenever it is required. It is integrated with the current system for energy storage as well as availing heat at a constant temperature. The present study will try to demonstrate the energy-saving by implementing the local heating with a spiral latent heat thermal energy storage system, when only a particular (local) space heating is of interest. In this work, an experimental as well as the numerical study of a dome over a bed was performed. Various heating coil configurations, namely floor coil, roof zig-zag, and roof spiral, were constructed to find the best configuration for the localized space heating. Experiments and simulations with the variable flow rate (0.25, 0.50, and 0.75 m/s) and varying inlet temperatures (55, 60, and 65°C) of the heat transfer fluid were carried out. It was found that the floor coil heating gives better results as compared with the other two. It was also seen that the effect of mass flow rate and inlet temperature was not that much significant after a limit. A temperature difference of 20°C was maintained between the space under consideration with the surrounding room.