Effect of turbulent fluctuation on the ignition of millimeter particle: Experimental studies and numerical modelling with a new correlation of nusselt number--颗粒学报PARTICUOLOGY

Feng, L., Liu, J., Xin, H., Jiang, L., Wu, Y., & Babaee, S. (2024). Effect of turbulent fluctuation on the ignition of millimeter particle: Experimental studies and numerical modelling with a new correlation of nusselt number. Particuology, 91, 168-175. https://doi.org/10.1016/j.partic.2024.03.002

Effect of turbulent fluctuation on the ignition of millimeter particle: Experimental studies and numerical modelling with a new correlation of nusselt number

Lele Feng ^a *, Jie Liu^{b c}, Haihui Xin^b, Liangliang Jiang^d *, Yuxin Wu^e, Saeideh Babaee^f

a Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization, China University of Mining and Technology, Xuzhou, 221008, China
b School of Safety Engineering, China University of Mining and Technology, Xuzhou, 221116, China
c Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials, Wuhan University of Science and Technology, Wuhan, 430000, China
d Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada
e Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China
f Department of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa

10.1016/j.partic.2024.03.002

Volume 91, August 2024, Pages 168-175

Received 7 January 2024, Revised 25 February 2024, Accepted 7 March 2024, Available online 19 March 2024, Version of Record 29 March 2024.

E-mail: fenglele@cumt.edu.cn; jial@ucalgary.ca

Highlights

• Effect of fluctuation on the ignition of millimeter particles is studied.

• Ranz-Marshall correlation and new proposed correlation of Nusselt number are compared.

• Effects of temperature, diameter, particle distance and coal type are investigated.

Abstract

Understanding the influencing mechanism of turbulent fluctuation on the ignition characteristics of millimeter coal particles is essential. In this work, to study the effect of turbulent fluctuation on ignition time, millimeter coal particles are subjected to a specific flow field, generated in a furnace with symmetric fans. A one-dimensional model with the new proposed correlation and the Ranz-Marshall (R-M) correlation for Nu (Nusselt number) is established to simulate the coal ignition process. In addition, the effects of fan speed, temperature, particle diameter, particle distance and coal type on the ignition time are investigated. It is found that an increase in fan speed from 0 to 3000 rpm leads to a particle Reynolds number Re_p increase from 0 to 22.5, and a turbulent particle Reynolds number Re_t∗ increase from 0 to 71.5. With a consideration of the fluctuation effect, the new correlation of Nu gives a better prediction of ignition time compared to the R-M correlation. Moreover, the ignition time is revealed to decrease with an increasing fan speed and an elevating temperature. While the ignition time shows merely an initial boost with enlarging particle distance, it exhibits a linearity with the term of particle diameter d_p^1.3–1.7 and Reynolds numbers (Nu∗/Nu)–0.6 (Nu∗ is turbulent Nusselt number). Based on this relationship, the difference of predicted ignition time is calculated at different Re_p and Re_t∗. It is shown that at low Re_p or high Re_t∗ values, the new correlation should substitute for the R-M correlation.

Graphical abstract

Keywords

Turbulent fluctuation; Particle heat transfer; Empirical correlation; Coal ignition

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