Performance analysis of a vertically oriented concentric-tube PCM based thermal energy storage system: Parametric study and correlation development

Abstract

Latent heat based thermal energy storage systems stores energy which can be retrieved whenever required. Total melting time (or melting rate) is an important parameter which governs suitability of any system for a given application. In the present work, a numerical analysis has been performed on the vertically orientated concentric double-pipe storage system. Effect of phase change material (PCM) properties, flow parameter and geometric parameters of the storage system on total PCM melting time are studied. Enthalpy-porosity technique has been used to model the phase change process apart from governing fluid flow and energy equations. It is found that with the increase in melting temperature and latent heat, the total melting time increases whereas the total melting time decreases with increase in the heat transfer fluid inlet temperature and aspect ratio. 74.11% decrease in the total melting time has been observed when melting temperature is decreased from 343 K to 323 K with latent heat 144 kJ/kg, heat transfer fluid inlet temperature 348 K and aspect ratio 11.76. A correlation for the total melting time comprehending the effect of all studied parameters has been developed which can provide the total melting time within ±15% accuracy.