Mixed convective heat transfer characteristics and mechanisms in structured packed beds--颗粒学报PARTICUOLOGY

Qu, Y., Wang, L., Lin, X., Chen, H., Zhang, S., Ling, H., & Bai, Y. (2023). Mixed convective heat transfer characteristics and mechanisms in structured packed beds. Particuology, 82, 122-133. https://doi.org/10.1016/j.partic.2023.01.014

Mixed convective heat transfer characteristics and mechanisms in structured packed beds

Yuelong Qu ^{a b}, Liang Wang ^{a b c}, Xipeng Lin ^{a b c *}, Haisheng Chen ^{a b c}, Shuang Zhang ^{a c}, Haoshu Ling ^{a c}, Yakai Bai ^{a c}

a Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, 100190, China
b University of Chinese Academy of Sciences, Beijing, 100049, China
c Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, 116023, China

10.1016/j.partic.2023.01.014

Volume 82, November 2023, Pages 122-133

Received 22 November 2022, Revised 18 January 2023, Accepted 24 January 2023, Available online 11 February 2023, Version of Record 15 February 2023.

E-mail: linxipeng@iet.cn

Highlights

• A coupling analysis was carried out on the unsteady process of the velocity and density fields.

• Influence of the driving force caused by density difference on fluid flow was revealed.

• Effect of natural convection on the field's synergy angle was analyzed.

• Influence of fluid-solid physical parameters on heat transfer was studied.

Abstract

The structured packed bed is considered a promising reactor owing to its low pressure drop and good heat transfer performance. In the heat transfer process of thermal storage in packed beds, natural convection plays an important role. To obtain the mixed convective heat transfer characteristics and mechanisms in packed beds, numerical simulations and coupling analyses were carried out in this study on the unsteady process of fluid flow and heat transfer. A three-dimensional model of the flow channel in the packed bed was established, and the Navier–Stokes equations and Laminar model were adopted for the computations. The effects of the driving force on fluid flow around a particle were studied in detail. The differences in velocity and density distributions under different flow directions due to effect of the aiding flow or opposing flow were intuitively demonstrated and quantitatively analyzed. It was found that the driving force strengthens the fluid flow near the particle surface when aiding flow occurs and inhibits the fluid flow when opposing flow occurs. The boundary layer structure was changed by the natural convection, which in turn influences the field synergy angle. For the aiding flow, the coordination between the velocity and density fields is higher than that for the opposing flow. By analysis the effects of physical parameters on mixed convective heat transfer, it is indicated that with an increase in the fluid-solid temperature difference or the particle diameter, or a decrease in the fluid temperature, the strengthening or inhibiting effect of natural convection on the heat transfer became more significant.

Graphical abstract

Keywords

Computational fluid dynamics; Packed beds; Natural convection; Heat transfer

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