Melting of phase change materials in horizontal annuli

This paper presents experimental results on melting of n-octadecane and dodecanoic acid in horizontal annuli with center-tubes of 18-, 27-, and 36-mm diameter and outer cylinder of 127-mm diameter. The PCMs were subcooled to 2.5, 7.5, 15.0, and 22.5 degrees C below, and heated at 8.44, 16.4, 25.3, 33.4, and 42.2 degrees C above their melting temperatures. Melt volumes per unit length of the enclosures and positions of solid-liquid interfaces were obtained photographically. A generic correlation is provided to predict the melt volume of PCMs for a wide range of geometric and thermal conditions. Also, the evolution of solid-liquid interfaces with time is presented. The results show that increasing the melting temperature differential from 8.44 to 25.3 degrees C increases the melting rate significantly and further increase does not affect the melting rate as much. A faster melting rate is observed for a larger center tube. Subcooling of the PCMs has a greater impact on the melting rates when the PCMs are heated at a low melting temperature differential. The PCMs play a significant role on the melting rate when they are heated at a low temperature; at high melting temperature differentials, the PCMs behave similarly. In addition to providing information on melting dynamics of the PCMs in horizontal annuli, these results provide a needed source for validation for numerical models.

Automated summary

This paper presents experimental results of melting characteristics of n-octadecane and dodecanoic acid in horizontal annuli with different geometric and thermal conditions. The study shows that the melting rate is affected by the melting temperature differential and the diameter of the center tube.