Abstract
The performance of thermal systems, like heating and cooling systems, depends on a number of factors such as the geometrical shape, the working fluid used to transfer or store heat, and the operating conditions. Accordingly, many studies concentrated on improving the thermal performance of such systems and raising their thermal efficiency by modifying their geometry or using phase-changing materials. Therefore, this work is reviewing the previous studies that dealt with modifying the geometry, by adding annular or longitudinal fins on the main tube of the heat exchanger, and employing different types of phase change materials. This article also presents the previous scientific articles that investigated the effects of changing the location and the orientation of the fins. For the reviewed studies in this article, it is worth mentioning that the numerical investigations outnumbered the experimental ones as the authors focused on finding the optimal design of the studied thermal systems. Furthermore, the previous studies employed phase-change materials, e.g. fatty acids, waxes, and salts, due to their ability to store energy and reuse it in a wide range of applications.
