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

•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.