Heat transfer improvement and fouling analysis of flue gas driven molten-salt-heat-exchanger with inclined tube and staggered H-type fins

Jie Gao, Xiongjiang Yu, Jinliang Xu, Yupu Yu, Bingyi Jiang, Qinghua Wang, Yuguang Niu and Jizhen Liu

Energy, 2025, vol. 333, issue C

Abstract: To increase the grid's renewable energy consumption, a thermal energy storage/release system is integrated into conventional coal-fired power units to achieve thermoelectric decoupling and enhance operational flexibility. The key innovation is a flue gas energy storage system with a flue gas driven molten-salt-heat-exchanger (MSHE) as the core component. This study proposes an inclined tube structure with a self-extraction function for the MSHE to improve molten salt operation safety. A three-dimensional model of flue gas flowing across a 10-row H-fin inclined tube is established to analyze flow and heat transfer characteristics, yielding velocity profiles, temperature distributions, fin-tube temperature differences, and heat transfer coefficients. Three tube configurations are compared, revealing that non-uniform longitudinal spacing induces oscillatory heat transfer coefficients across tube rows while maintaining equivalent performance to uniform spacing configurations. Based on the non-uniform longitudinal spacing configuration, an innovative staggered fin arrangement is proposed, achieving an 18 % higher downstream fin-tube temperature difference and improved heat transfer. Additionally, ash particle entrainment analysis shows that the staggered arrangement reduces backflow ash particle concentrations by regulating the flow field at the H-type fin gaps, minimizing ash deposition risks. These findings offer valuable guidance for optimizing and applying the novel flue gas-driven MSHE.

Keywords: Flue gas driven molten-salt-heat-exchanger; Heat transfer coefficient; Tube configurations; Fin arrangement; Flow field; Fouling (search for similar items in EconPapers)
Date: 2025
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:333:y:2025:i:c:s036054422503035x

DOI: 10.1016/j.energy.2025.137393

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