Experimental investigation during the melting process of a vertical and horizontal tube-in-shell Latent Heat Energy Storage System

Abstract

Thermal energy storage systems with the application of Phase Change Materials have been in practice for many years due to their ability to store latent heat energy and have been applied for energy storage and thermal comfortability. It is essential to constantly explore various methods to enhance the performance of such Latent Heat Energy Storage Systems to develop a more effective system. Research in improving the performance of these storage systems through different orientations of the system has been limited. There has been little mention of the effectiveness of the different orientations of Latent Heat Energy Storage Systems at a system level. The study filled the research void by applying an effectiveness technique to explicitly quantify and evaluate the performance of the systems with different orientations from the perspective of a heat exchanger. An experimental investigation was performed on the static melting process of vertical and horizontal tube-in-shell Latent Heat Energy Storage Systems to investigate the effect of the different heat transfer fluid flow rates and the system orientations. Experiments were performed for 3 different heat transfer fluid flow rates (0.35 l/min, 0.7 l/min, and 1.4 l/min). From the experimental investigations, it was deduced that the horizontally oriented Latent Heat Energy Storage System had a higher melting rate in comparison to the vertical orientation, causing the phase change material to melt in a shorter period at all heat transfer fluid flow rates investigated. By examining the performance of the system as an effective heat exchanger, the horizontal Latent Heat Energy Storage System was observed to be at least 36 %, 30 %, and 47 % more effective than the vertical systems for the heat transfer fluid flow rates of 1.4 l/min, 0.7 l/min, and 0.35 l/min, respectively. The performance variation of the horizontal and vertical Latent Heat Energy Storage System was attributed to the variation in the convective heat transfer mechanism driven by the buoyancy forces within the phase change material as it melts.