The study of constrained and unconstrained PCM melt in a square enclosure.
Morven Louis Thevathasan.
Date of Issue2013
School of Mechanical and Aerospace Engineering
The use of a latent heat storage system using PCM is an effective way of storing thermal energy. Over the years, many studies of PCM have incorporated the use of various shaped enclosures such as spherical and rectangular, to study its melting behaviour. However, the use of square shaped enclosures in PCM studies, are limited. This report will focus on the effects of temperature and free surface in constrained and unconstrained n-Octadecane contained in a square enclosure. The experiment was carried out in three stages. The first stage was to study the unconstrained PCM melting under constant temperatures of 40oC and 50oC. The second stage was to study free surface effects in the melting of constrained and unconstrained PCM under constant temperature of 40oC. While, the final stage was to study the overall effects of free surface in PCM. The PCM was immersed in water and exposed to a constant temperature, maintained by a circulatory bath, until full melting was obtained. Experimental results concluded that the effects of temperature exposed to the PCM had a significant influence towards its melt rate and the nature of internal convection present. The melting pattern of PCM indicated that surface area of solid PCM in contact with the liquid played an effective role in heat transfer. In the study of free surface effects on n-Octadecane in a square enclosure, it was proven that with the inclusion of free surface, significant changes were observed in the melting behaviour of the PCM. This was predominantly due to the presence of air. Lastly, constrained melting of n-Octadecane showed the existence of thermally stable and unstable fluid layers. In comparison with similar experiments performed previously, it is concluded that such stable and unstable fluid layers are present regardless the manner of encapsulation and the existence of free surface.
Final Year Project (FYP)
Nanyang Technological University