A parametric experimental investigation of the heat transfer in a coil-in-tank latent heat energy storage system

An experimental characterization of a latent heat energy storage system (LHESS) with dodecanoic acid as the phase change material and a coil-in-tank heat exchanger was conducted in order to evaluate the effects of various operating parameters on the heat transfer in the system. During charging it was found that natural convection played a significant role, while discharging was mainly dominated by conduction. The heat transfer fluid (HTF) inlet temperature during charging affected the overall performance more significantly than the HTF flow rate. Experiments showed that discharge time was significantly longer than charging due to the heat exchanger having an ever-growing layer of solid PCM surrounding it throughout the process. More importantly, heat transfer rates are characterized under the various operating condition for this specific heat exchange geometry. Therefore, this study illustrates the extent to which heat exchangers designs need to be improved in order to meet the desired time requirements for most short-term storage applications.