Enhanced latent heat thermal energy storage in the double tubes using fins

Research on latent heat thermal energy storage (LHTES) inside double tubes is performed numerically. The commercially available paraffin wax RT82 is used as a phase change material (PCM) with melting temperature of 350.15-358.15 K. The effect of fins number (N) varies from 2 to 10, and boundary conditions of the outer tube wall on the melting process are examined in detail. The constant wall temperature of 368.15 K or heat flux of 2800 W m(-2) is maintained at the outer tube wall. It is found that fins number and boundary conditions of outer tube wall play an important role in the thermal performances of LHTES. The melting rates increase as the fins number increases, especially for N = 10. Moreover, for enhanced cases, it is noted that multi-circulation region in the liquid PCM region is formed remarkably due to the stronger natural convection of liquid PCM and separate cavity zone. It is indicated that heat conduction is the dominant heat transfer mode during the melting early stage. Then, the heat transfer mode transition from heat conduction to natural convection. At the end of melting stage, natural convection is dominated the melting heat transfer. Furthermore, the numerical model is validated using the experimental data.