Experimental study of the effect of inclination angle on the paraffin melting process in a square cavity

Abstract

Abstract The transient melting process of a phase change material (PCM) is strongly affected by its inclination angle caused by the behavior of buoyancy-driven natural convection. An experimental study is carried out to investigate the effect of this inclination on the thermal behavior during PCM melting contained in a square cavity. The range of inclination angle from 0° (vertical), 45° (inclined) and 90° (bottom) is considered. Paraffin with a melting range of 49-54°C is used as PCM. The volumetric shrinkage of PCM during solidification preceding the melting experiments leads to the development of a large void in the free surface PCM-air. The effects of inclination and shrinkage phenomenon are analyzed by visualizing the solid-liquid interface and measuring temperatures by thermocouples and infrared camera. Results show that the inclination angle has a great influence on the natural convection behavior, and affects the melting front progression and the heat transfer rate. The total melting time for the bottom and inclined cavities cases were, on average, 56% and 48% less than the vertical one, respectively. The volumetric shrinkage disrupts significantly the melting process in the vertical and inclined cases. The natural convection is more intense in the bottom case and the global average Nusselt number increases during the strong convection by about 10% and 21% compared to the inclined and vertical cases, respectively.