Numerical investigation of tube oscillation in gravity-driven granular flow with heat transfer by discrete element method

Zhigang Guo, Shang Zhang, Xing Tian, Jian Yang and Qiuwang Wang

Energy, 2020, vol. 207, issue C

Abstract: In this paper, the gravity-driven granular flow was investigated by discrete element method (DEM) in the moving bed heat exchanger with tube oscillation. The particle update, the particle contact and the heat transfer were all discussed around tube out-wall. Moreover, the heat resistance analysis was developed to reveal the heat transfer mechanisms. It was found that, tube oscillation can significantly improve heat transfer coefficients (h). The relative growth of locally optimal h varies from 59.2% to 22.6%, when the outlet velocity (u) ranges from 0.65 mm/s to 6 mm/s. In details, the heat transfer can be enhanced by tube oscillation due to the smoother flow in the upstream, the denser contact in the downstream and the more particle mixing inside the flow. However, the particle separation aside the tube has a negative effect simultaneously. Therefore, there is a best frequency (f) to optimize h. The frequency is inversely proportional to the amplitude (DA) and decreases with u. Furthermore, the larger DA can increase the best h. In the present study, the optimal h was obtained as f locates between 3 and 5 Hz at DA > 1 mm.

Keywords: Moving bed heat exchanger; Gravity-driven granular flow; Tube oscillation; Heat transfer enhancement; Discrete element method (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:207:y:2020:i:c:s0360544220313104

DOI: 10.1016/j.energy.2020.118203

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