Experimental investigation on melting heat transfer characteristics of lauric acid in a rectangular thermal storage unit

This paper presents an experimental effort to visualize temperature field and melt front evolution during solid-liquid phase change process. The study is focused on the melting of lauric acid in a rectangular thermal storage unit heated from one side. Thermophysical properties of lauric acid are determined and found to be desirable for application as a medium temperature phase change material (PCM). Image processing of photographs together with recorded temperatures are used to calculate the melt fractions, temporal heat storage and heat transfer characteristics, including the average Nusselt number on the hot wall as well as the local heat transfer rates on the melt front. Moreover, solid-liquid interface morphology and temperature field are employed to infer dominant heat transfer mechanisms and time-dependent flow structures during different stages of the melting process. Results indicate that during the initial stage of melting, heat conduction is the dominant mode of heat transfer, followed by transition from conduction to convection regime and convection dominated heat transfer at later times. Approaching the end of the melting process, bulk temperature of the liquid PCM increases and stratified temperature field appears at upper part of the enclosure which reveals depression of the convection currents.