Thermal performance investigations of the melting and solidification in differently shaped macro-capsules saturated with phase change material

Highlights

• The visualization of the liquid-solid interface in differently shaped macro-capsules is carried out.

• A triangular capsule shows better thermal performance than the spherical, cubical, and plus shaped capsules.

• An increase in the heat transfer fluid temperature enhances the melting rate significantly.

• A decrease in capsule size improves both the melting rate with more influence on the solidification rate.

Abstract

The storage of phase change material in the macro-capsules used for a latent thermal energy storage system significantly enhances the thermal performance compared to the conventional shell and tube heat exchanger. The geometrical shape and dimensions of these capsules have a major impact on the melting and solidification characterization. Most of the research is, however, carried out using a spherical capsule only. Hence, the influence of the differently shaped macro-capsules is required to be evaluated to obtain thermal performance enhancement. An experimental setup is developed to validate numerical observations. The primary objective of the present study is to visualize the phase change phenomenon and compare the thermal behavior of differently shaped capsules (spherical, cubical, triangular, and plus-shaped) during the melting and solidification processes. Results show that the triangular capsule exhibits better thermal performance with melting and solidification time of 41 min and 133 min, respectively. In addition, the increase in the heat transfer fluid temperature increases the melting rate. Furthermore, it is found that the 27% reduction in the capsule size decreases melting and solidification time by 12.19 and 19.17%, respectively. Hence, the capsule size has more influence on the solidification process compared to the melting process.