Experimental investigation of melting behaviour of phase change material in finned rectangular enclosures under different inclination angles

Abstract

The deployment of phase change materials (PCMs) in practical applications is in large part limited by the low thermal conductivity of the available PCMs. Hence, in this study, enhancement in the melting rate of PCM by addition of fins in rectangular enclosures was experimentally investigated under different inclination angles. The melting process of lauric acid in side-heated enclosures with different numbers of fins was evaluated for inclination angles of 90° (vertical), 45° and 0° (horizontal). In order to visualize the melting process, the enclosure was fabricated from transparent acrylic material except one side made of an aluminum plate to heat the enclosure isothermally. Solid-liquid interface positions and temperature history of the PCM were recorded and applied to calculate the liquid fractions and heat transfer rates. The evolution of the interface in the inclined enclosures revealed that the development of vortical flow structures in the liquid PCM by decreasing the inclination angle significantly improves the melting rate. It was found that for both finned and unfinned enclosures the melting rate increases by reducing the inclination angle. Heat transfer enhancements obtained by the 0-fin horizontal and 3-fin vertical enclosures compared to the 0-fin vertical enclosure were 115% and 56%, respectively. This thermal behavior proposes that simply inclining the enclosure can be more effective to enhance the melting rate than adding fins to the vertical enclosure. Among the different cases studied, the 3-fin horizontal enclosure showed the maximum heat transfer rate and consequently the minimum melting time. The present investigation can contribute to a better understanding of PCM melting in the inclined finned enclosures and provide much-needed benchmark data for the future numerical simulations.