在线阅读

在线阅读

Partic. vol. 46 pp. 75-82 (October 2019)
doi: 10.1016/j.partic.2018.10.005

Numerical study of collection efficiency and heat-transfer characteristics of packed granular filter

Junlin Chena,b, Xunfeng Lia,b,*, Xiulan Huaia,b,*, Yongwei Wanga,b, Jingzhi Zhoua,b

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lixunfeng@iet.cnhxl@iet.cn

Highlights

    • Three-dimensional randomly packed granular filtration model was built. • Grade collection efficiency increased linearly with lg(St) when St ≥ 0.009. • Introduction of solid particles to packed bed could enhance heat transfer. • Heat-transfer enhancement increased approximately linearly with particle loading. • Nusselt number correlation was obtained under low Reynolds number conditions.

Abstract

The collection mechanism and heat-transfer characteristics of a packed granular filter were investigated using a three-dimensional randomly packed granular filter model. The bridging method was introduced to optimize the grids of contact points between granules. The influences of granular bed depth, gas velocity, and gas temperature on grade collection efficiency were investigated. The results indicated that a decrease of temperature improved collection efficiency when the particle diameter was greater than 5 μm. The grade collection efficiency maintained a stable value when the Stokes number, St, was less than 0.009, but increased linearly with lg(St) when St ≥ 0.009. A logarithmic mean temperature difference method was used to obtain overall heat-transfer coefficients of gas–solid two-phase flow through the packed granular filter. The results showed that convective heat transfer was enhanced due to the introduction of solid particles in the bed. The overall heat-transfer coefficient increased approximately linearly with an increase in particle loading ratio. The Nusselt number was related to the Reynolds number, the Archimedes number, and the particle loading ratio.

Graphical abstract

Keywords

Packed granular filter; Gas–solid two-phase flow; Grade collection efficiency; Heat transfer