Melting and solidification performance investigation of latent heat storage unit designs for low-temperature solar thermal applications

Integrating latent heat storage with solar thermal systems is a promising way to deal with the problem that solar energy is not always available or is only available for short periods of time. An efficient design for latent heat storage is the shell and tube type latent heat storage unit (ST-LHSU). Literature suggests that the performance of ST-LHSU can be improved significantly by modification in design. Therefore, the current article presents a comparative investigation of different horizontal ST-LHSU designs for melting/solidification performances. For this study, four alternative ST-LHSU designs representing the changes in the outer shell's cross-sectional area have been chosen. A validated two-dimensional numerical model for the selected ST-LHSU designs has been formulated and solved using the commercially available CFD solver. In the initial phase, the selected ST-LHSU designs have compared for melting and solidification performance. Complete melting in Design-IV happens 25.5 % and 37.4 % faster than in Design-III and Design-I, respectively. Design-I was the most effective design for entire solidification since it reached complete solidification 3.65 %, 19.57 %, and 45.02 % faster than Designs-II, III, and IV, respectively. In the second phase, the modification in Design-I has been done to reduce its total thermal cycle time. The total thermal cycle time of the modified Design-I is 24.58 % shorter than that of the original Design-I, 37.94 %, and 40.21 % shorter than Design-III and IV, respectively. The utilization of melting/ solidification techniques like fins, metal foam, and nanoparticles can be studied in the future with the modified Design-I.

Automated summary

This article presents a comparative investigation of different horizontal shell and tube latent heat storage unit (ST-LHSU) designs for melting/solidification performances. The results show that Design-IV has a significantly faster melting rate than Design-III and Design-I, completing the process 25.5% and 37.4% faster, respectively. Furthermore, Design-I is the most effective design for solidification, achieving complete solidification 3.65%, 19.57%, and 45.02% faster than Designs-II, III, and IV. Additionally, modification in Design-I reduces the total thermal cycle time by 24.58%, 37.94%, and 40.21% compared to the original Design-I, Design-III, and Design-IV.