Experimental study of a latent heat thermal energy storage system assisted by varying annular fins

Abstract

Latent heat thermal energy storage (LHTES) systems can be used to alleviate the intermittent nature of solar power by allowing energy to be stored and released when needed. LHTES systems utilize phase change materials (PCMs) for energy storage, and a frequent problem with most PCMs is the low thermal conductivity. Annular fins of variable diameter are used to increase the heat transfer rate to and from the PCM. A shell and tube heat exchanger filled with PCM uses a central pipe with annular fins to carry the heat transfer fluid through the system. All fin configurations in this study contain the same volume of copper but are designed differently. The benchmark case with no fins had charging and discharging times of 47.87 and 42.5 h, respectively. The ten-annular fin cases include: uniform fins, increasing fin diameter from top to bottom, and decreasing fin diameter from top to bottom which decreased the charging time by 84.1 %, 85.77 %, and 58.5 %, respectively. These cases decreased the discharging time by 68.21 %, 65.34 %, and 44.0 %, respectively. Similar designs with twenty annular fins decreased the charging time by 85.50 %, 89.45 %, and 71.00 %, respectively. These cases decreased the discharging time by 68.58 %, 77.41 %, and 44.28 %, respectively.