Particle convective heat transfer near the wall in a supercritical water fluidized bed by single particle model coupled with CFD-DEM |
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| Institution: | 1. State Key Laboratory of Multiphase Flow in Power Engineering (SKLMFPE), Xi''an Jiaotong University, Xi''an, 710049, Shaanxi, China;2. Xi''an Electronic Engineering Research Institute, Xi''an, 710100, Shaanxi, China;1. Department of Medical Physics, Faculty of Physics, Institute of Physics, Jagiellonian University, Cracow, Poland;2. Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Pharmacy, Collegium Medicum, Jagiellonian University, Cracow, Poland;3. Faculty of Chemistry, Jagiellonian University, Cracow, Poland;1. Guangdong Provincial Key Lab of Green Chemical Product Technology, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China;2. Zhuhai Institute of Modern Industrial Innovation, South China University of Technology, Zhuhai, 519175, China;3. School of Chemical Engineering, Guangdong University of Petrochemical Technology, Maoming, 525000, China;1. School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China;2. School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China;3. School of Engineering, Newcastle University, NE1 7RU, United Kingdom;1. School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China;2. School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China;3. State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing, 100084, China;4. School of Engineering, Newcastle University, NE1 7RU, United Kingdom;1. State Key Laboratory of Power Systems, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China;2. China Electric Power Planning & Engineering Institute, Beijing, 100120, China;3. SDIC Power Holding Co., Ltd, Beijing, 100034, China;1. School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China;2. Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario, N6A 3K7, Canada;3. Institute of Shaoxing, Tianjin University, Zhejiang, 312300, China |
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| Abstract: | Supercritical water fluidized bed (SCWFB) is a promising reactor to gasify biomass or coal. Its optimization design is closely related to wall-to-bed heat transfer, where particle convective heat transfer plays an important role. This paper evaluates the particle convective heat transfer coefficient (hpc) at the wall in SCWFB using the single particle model. The critical parameters in the single particle model which is difficult to get experimentally are obtained by the computational fluid dynamics-discrete element method (CFD-DEM). The contact statistics related to particle-to-wall heat transfer, such as contact number and contact distance, are also presented. The results show that particle residence time (τ), as the key parameter to evaluate hpc, is found to decrease with rising velocity, while increase with larger thermal boundary layer thickness. τ follows a gamma function initially adopted in the gas–solid fluidized bed, making it possible to evaluate hpc in SCWFB by a simplified single particle model. The theoretical predicted hpc tends to increase with rising thermal gradient thickness at a lower velocity (1.5 Umf), while first decreases and then increases at higher velocity (1.75 and 2 Umf). hpc occupies 30%–57% of the overall wall-to-bed heat transfer coefficient for a particle diameter of 0.25 mm. The results are helpful to predict the overall wall-to-bed heat transfer coefficient in SCWFB combined with a reasonable fluid convective heat transfer model from a theoretical perspective. |
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| Keywords: | Supercritical water Fluidized bed Particle residence time Discrete element method Single particle model |
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