Article (Scientific journals)
Particle scale modeling of heat transfer in granular flows in a double screw reactor
Qi, Fenglei; Wright, Mark
2018In Powder Technology, 335, p. 18-34
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10.1016j.powtec.2018.04.068 (1).pdf
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Keywords :
Biomass granular flow; Double screw reactor; Heat transfer cofficient; Radiation
Abstract :
[en] Heat transfer in granular flows plays an important role in particulate material processing such as food production, pharmaceuticals and biorenewable energy production. Better understanding of the thermodynamics in granular flows is essential for equipment design and product quality control. In this research, a particle-scale heat transfer model was developed within the frame of traditional Discrete Element Method (DEM), which considers both conductive heat transfer and radiative heat transfer among particles. A particle-wall heat transfer model was also proposed for resolving particle-wall conductive and radiative heat transfer. The developed thermal DEM model was validated by modeling heat transfer in packed beds and comparing simulation predictions with experimental measurements. The thermal DEM model was successfully applied to the simulation of heat transfer in binary component granular flows in a double screw reactor designed for biomass fast pyrolysis to gain better understanding of the heat transfer in the system. The existence of both spatial and temporal temperature oscillations is observed in the double screw reactor. The effects of the operating conditions on the average temperature profile, biomass particle temperature probability distribution, heat flux and heat transfer coefficient are analyzed. Results indicate that the particle-fluid-particle conductive heat transfer pathways are the dominant contributors to the total heat flux, which accounts for approximately 70%–80% in the total heat flux. Radiative heat transfer contributes 14%–26% to the total heat flux and the conductive heat transfer through contact surface takes only 1%–5% in the total heat flux. The total heat transfer coefficient in the double screw reactor is also reported, which varies from 70 to 110 W / (m 2 • K) depending on the operating conditions.
Disciplines :
Mechanical engineering
Author, co-author :
Qi, Fenglei ;  University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit
Wright, Mark;  Iowa State University > Mechanical Enigneering
External co-authors :
Language :
Title :
Particle scale modeling of heat transfer in granular flows in a double screw reactor
Publication date :
Journal title :
Powder Technology
Publisher :
Elsevier, Lausanne, Netherlands
Volume :
Pages :
Peer reviewed :
Peer Reviewed verified by ORBi
Focus Area :
Physics and Materials Science
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since 30 August 2019


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