Yasser Amini

Energy storage is one of the effective methods in improving energy consumption that can have an important role in environment preservation and reducing energy costs. One of the energy storage methods is using phase change materials. These materials can store or release significant amounts of energy during melting or solidification processes. One of the main challenges in utilizing these materials is their low heat transfer rate due to their specific thermophysical properties. Accordingly, researchers have conducted extensive research on this topic. In this thesis, the effect of fin geometry on improving energy storage has been investigated. For this purpose, a double-tube heat exchanger with fins installed on the outer surface of the inner tube has been numerically studied. Hot or cold fluid passes through the inner tube and phase change materials are placed in the space between the two tubes. Six different fin geometries with curved and triangular cross sections have been examined and compared during charging and discharging processes. Also, for the best performing fin geometry, the effect of non-uniform fin spacing has been studied. It should be noted that the phase change material volume is the same in all cases. For more precise analysis, the results have been presented as temperature and liquid fraction contours, streamlines, isotherms, liquid fraction variations versus time, exergy efficiency and energy diagrams. The results showed that fin geometry plays an important role in enhancing heat transfer and can reduce charging time by up to 15% and discharging time by up to 23%. Also, concentrating fins at the bottom of the heat exchanger can reduce charging time by about 13%.