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Simulation of large biomass pellets in fluidized bed by DEM-CFD
Zhaoping Zhong,Lingli Zhu,Heng Wang,Zeyu Wang 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.10
An improved numerical model was proposed to solve the problem that the traditional DEM-CFD (Discrete element method-computational fluid dynamics) method was not suitable for the flow simulation of large particles. In the improved model, the large particle was regarded as an agglomerate of many small fictitious spheres. Herein, the drag force between gas and large pellets was assumed as a combined effect of that between gas and fictitious spheres by volume penalty method. Based on the proposed model, the flow of the mixtures of large biomass pellets and quartz sands in fluidized bed was simulated. It shows that the existence of the biomass pellets has a great impact on the flow field. The flow patterns and pressure drops under different working conditions in simulation results have a good agreement with that in experimental results partially, which also tests the proposed model.
Xiaoyi Wang,Zhaoping Zhong,Heng Wang,Zeyu Wang 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.1
Hilbert-Huang transformation was used to investigate the nonlinear characteristics of two-component (bio-mass particles and quartz sand) mixing flow by analyzing the pressure fluctuation signals in fluidized bed. Based onempirical mode decomposition (EMD), the Hilbert-Huang spectra in bubbling and slugging flow patterns were ob-tained and analyzed. In bubbling flow pattern, compared with one-component (quartz sand) flow, the energy of two-component mixing flow is lower in 0-5 Hz and higher in 40-50 Hz. In slugging flow pattern, the energy in pressurefluctuation mainly lies in 0-5 Hz. and the effect of biomass particles on the Hilbert-Huang spectrum is not very obvi-ous. Compared with traditional power spectral density (PSD), HHT is much more suitable for investigating pressurefluctuation signals in fluidized beds.