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Experimental study on the heat-transfer mechanisms and thermophysical characteristics of flue gas–molten salt systems

Author

Listed:
  • Li, Huaan
  • Liu, Xiang
  • Ye, Huan
  • Zhang, Zhengshun
  • Wang, Yupeng
  • Yu, Zezhong
  • Zhou, Tianxing
  • Wu, Yajie
  • Wang, Ziqi
  • Zhou, Hao

Abstract

The recovery of heat from industrial flue gas (FG) significantly contributes to improving energy efficiency and lowering emissions. To explore the heat transfer characteristics between FG and molten salt (MS), this study presents the development of an experimental device for a flue gas - molten salt heat exchanger (FGMSHE), which has not been previously established. Experimental investigations are carried out under various operating conditions to better understand the system's behavior. One of the primary challenges is the potential for MS freezing, which could impede the experimental process1. To address MS freezing during start-up and heat transfer imbalance, this study introduces a preheating regulation method with dynamic criteria to analyze FG–MS heat absorption in the preheating stage. By combining a fully opened MS pump with real-time electric heating control, the method achieves heat transfer balance, improves measurement accuracy, and establishes stable operating conditions, thereby ensuring reliable experimental data. Subsequently, the study examined the evolution of system performance throughout the balancing process. Key parameters such as FG temperature, FG flow rate, MS temperature, and MS flow rate are identified as crucial factors influencing the heat transfer performance. Using these parameters, multiple steady-state performance tests are conducted to determine the convective heat transfer coefficient (K) between the FG and MS. Finally, a comprehensive investigation into the variable-load characteristics of the FGMSHE system is conducted, focusing on the dynamic response of the heat absorption process to changes in FG temperature and MS flow rate. The analysis revealed that boosting the FG flow rate, FG temperature, MS flow rate, and reducing the MS inlet temperature all contribute to a higher heat utilization rate of FG. Raising the FG temperature from 560 °C to 600 °C enhances the K from 61.37 to 66.17 W/(m2·K), while increasing the MS flow rate from 1.7 to 3.6 kg/s elevates the K from 62.55 to 66.54 W/(m2·K).

Suggested Citation

  • Li, Huaan & Liu, Xiang & Ye, Huan & Zhang, Zhengshun & Wang, Yupeng & Yu, Zezhong & Zhou, Tianxing & Wu, Yajie & Wang, Ziqi & Zhou, Hao, 2025. "Experimental study on the heat-transfer mechanisms and thermophysical characteristics of flue gas–molten salt systems," Energy, Elsevier, vol. 341(C).
    • Handle: RePEc:eee:energy:v:341:y:2025:i:c:s0360544225050601
    DOI: 10.1016/j.energy.2025.139418
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    References listed on IDEAS

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