Design of non-uniformly distributed annular fins for a shell-and-tube thermal energy storage unit. (1st December 2020)

• Record Type: Journal Article
• Authors: Yang, Xiaohu; Guo, Junfei; Yang, Bo; Cheng, Haonan; Wei, Pan; He, Ya-Ling
• Is Part Of: Applied energy. Volume 279(2020)
• Publication Date: 2020-12-01
• Subjects: Phase change materials -- Annular fins -- Melting phase change -- Non-uniform design -- Shell and tube exchanger; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2020.115772
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: Non-uniformly distributed annular fins markedly reduced full melting time. Moving fins down effectively improve melting fraction of middle and bottom PCMs. An 84.7% improvement in melting uniformity was achieved by non-uniform design. Excessively moving fins down worsens uniformity of melting rate and temperature. Abstract: The shell and tube latent heat thermal energy storage systems are widely recognized as one of the most effective ways to store and utilize solar energy due to their high energy density, constant storage/releasing temperature, structural feasibility and rational price. The application of fins is an effective method to enhance heat exchange through extend the heat transfer surface area. However, there existed strong uneven melting behavior including melting fraction, temperature uniformity in a vertical thermal energy storage unit. To improve its uniformity of melting fraction and temperature, this study designed various conditions for fin pitch and positions in a non-uniform pattern to reduce the inhomogeneity for the melting process. Numerical models were established and validated by the experimental measurement conducted in this study. The effects of fin pitch and position on the thermal performance of the melting process were quantified via analyzing the melting front evolution, temperature and velocity distribution, melting rate and temperature uniformity. Results demonstrated that a 62.8% and 34.4% reduction in full melting time and average temperature difference in the phase change material region was separately obtained for the thermal energy storage unit with non-uniformly distributed annular fins, compared to the original case with uniform fins. Besides, the melting rate uniformity was also improved by 84.7%. The non-uniform design on fin position and pitch give a perspective to enriching the design methods for practical application in engineering.