Model for induced airflow velocity of falling materials in semi-closed transfer station based on similitude theory

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Japan, 2015-01, Vol.26 (1), p.236-243
• Main Authors: Li, Xiaochuan, Li, Qiang, Zhang, Dong, Jia, Binbin, Luo, Huiqing, Hu, Yafei
• Format: Article
• Language: English
• Subjects: Induced airflow; Pi theorem; Semi-closed transfer station; Similitude theory
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2014.10.003

1. Re=8926.9Gr0.272; 2. Re =7418.8 Gr0.268; 3. Re =5698.4Gr0.271; 4. Re =4114.3 Gr0.267;5. Re =2335.8Gr0.274. Relationship between Re and Gr numbers. From this figure, it can get to know that the Re number is increased with the increase of Gr number. The fitting power functions of these two dimensionless parameters show that the power exponents of power function level off at 0.27, and the coefficients of power function are increased when the h/D value is increased. [Display omitted] •The induced airflow was studied by using the Pi theorem and similitude experiments.•In this paper the specific induced airflow was a bit higher than existing results.•The falling particles of transfer station are in the acceleration phase from beginning to end.•The semi-empirical model of induced airflow velocity has been established. The dimensionless parameters of a pipe flow’s Reynolds number (Re), mass flow-rate number (mp/(μD)), specific induced airflow number (ρp·(ugD2/mp)), height number (h/D), and granular-flow number (Gr) were obtained by using the Pi theorem. The influences of mp/(μD), ρp·(ugD2/mp), and h/D to the Re were explored by similitude experiments. Finally, the semi-empirical model of induced airflow velocity was established through the Gr and Re. The conclusions are as follows: in the semi-closed transfer station, the Re value increased with the increase of the mp/(μD) value. Due to the interaction among the particles and change of the specific flow space of the blanking tube on the specific induced air flow, the ρp·(ugD2/mp) value was found to be proportional to the mp/(μD) value raised to the power of approximately −0.73. Due to limitations of drop heights, particles should be in the acceleration phase from beginning to end, when the resistance drag of the particles is less than the gravity of itself. It was also discovered that the Re value is proportional to the h/D value raised to the power of approximately 0.88. Additionally, similitude experiment results revealed that the Re value is proportional to the Gr value raised to the power of approximately 0.27. On this basis, the semi-empirical model for induced airflow velocity was established. The model can forecast actual values accurately with a deviation of the calculated values limited to plus or minus 10%. These research results can benefit industries in their transfer station dust control systems and in the design of ventilation systems.