Effect of sinusoidal cylindrical surface of PCM on melting performance

A numerical analysis was conducted to examine the effect of capsule shape on phase change material (PCM) melting speed. The surface parameters of the irregular capsule shape were amplitude a and the number of sinusoidal undulations n. Case studies were conducted: (1) with the same number of sinusoids but variable amplitude, (2) with the same amplitude but variable number of sinusoids, and (3) same PCM volume, i.e., the same irregular cylindrical capsule perimeter. Unlike observations with a convection-only inside capsule, the amplitude of irregularity in capsule shape a, rather than capsule area, was found to be the dominant factor in heat transfer enhancement. The capsule area was important only during the initial conduction-dominant period. The opposing influences of amplitude a and number of sinusoidal undulations n on the intensity of natural convection was observed. The result shows that only increasing the area does not increase the melting performance, it is the amplitude a which enhance the melting performance.