Study of wall-to-bed heat transfer in a bubbling fluidised bed using the kinetic theory of granular flow

Armstrong, Lindsay-Marie; Gu, Sai; Luo, Kai H.

doi:10.1016/j.ijheatmasstransfer.2010.05.047

Cited by 82 publications

(27 citation statements)

References 39 publications

(70 reference statements)

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“…(11). An estimate of the effective conductivity of the bed can be obtained from the Zehner-Schlünder model for stagnant thermal conductivity, which has been used in several studies [28,29] K)] in agreement with the experimentally fitted value. Moreover, when the bed is fluidized, the contacting surface of the gas and particles are continuously renewed by random particle fluctuations.…”

Section: Resultsmentioning

confidence: 97%

Experimental and simulation study of heat transfer in fluidized beds with heat production

Janssen

Buist

et al. 2017

Chemical Engineering Journal

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h i g h l i g h t sHeat production in a fluidized bed by CO 2 adsorption on Zeolite 13X. Combined infrared/visual camera (PIV-DIA-IR) technique for studying heat transfer. Extensive validation though a combined CFD-DEM model. Key aspects of adsorption process studied with TGA and STA. a r t i c l e i n f o b s t r a c tAs a result of highly exothermic reactions during gas-phase olefin polymerization in fluidized bed reactors, difficulties with respect to the heat management play an important role in the optimization of these reactors. To obtain a better understanding of the particle temperature distribution in fluidized beds, a high speed infrared (IR) camera and a visual camera have been coupled to capture the hydrodynamic and thermal behavior of a pseudo-2D fluidized bed. The experimental data were subsequently used to validate an in-house developed computational fluid dynamics and discrete element model (CFD-DEM). In order to mimic the heat effect due to the exothermic polymerization reaction, a model system was used. In this model system, heat is released in zeolite 13X particles (1.8-2.0 mm, Geldart D type) due to the adsorption of CO 2 . All key aspects of the adsorption process (kinetics, equilibrium and heat effect) were studied separately using Thermogravimetric Analysis (TGA) and Simultaneous Thermal Analysis (STA), and subsequently fluidized bed experiments were conducted, by feeding gas mixtures of CO 2 and N 2 with different CO 2 concentrations to the bed, where the total heat of liberation could be controlled. The combined infrared/visual camera technique generated detailed information on the thermal behavior of the bed. Furthermore, the comparison of the spatial and temporal distributions of the particle temperature measured in the fluidized bed with the simulation results of CFD-DEM provides qualitative and quantitative validation of the CFD-DEM, in particular concerning the thermal aspects.

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Section: Resultsmentioning

confidence: 97%

Experimental and simulation study of heat transfer in fluidized beds with heat production

Janssen

Buist

et al. 2017

Chemical Engineering Journal

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“…It is found that the simulation value for =0.3 is closer to the experimental value. Therefore, the specularity coefficient 0.3, which is very close to = 0.25 used by Armstrong et al [30,54] , for the partial-slip boundary condition is selected to simulate the flow of gas and particles in two catalyst coolers. The selected specularity value is also consistent with the recommendations from Bakshi et al [55] , who suggested that values of shall be n the range of [0.01, 0.3] to simulate dense solid-gas flows.…”

Section: Specularity Coefficientmentioning

confidence: 99%

“…Moreover, another researches aimed to obtain the relation between the gas-solids hydrodynamics and bed-to-tube heat transfer in a fluidized bed with immersed heated tube. Armstrong et al [30] used a two-fluid Eulerian-Eulerian formulation incorporating the KTGF to simulate the 2D fluidized bed with horizontal heated immersed tubes. Results showed that increasing the number of tubes promoted heat transfer from tubes to the particles and flow.…”

Section: Introductionmentioning

confidence: 99%

CFD investigation of gas-solids flow in a new fluidized catalyst cooler

Yao

Zhang

et al. 2016

Powder Technology

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In our previous work, a new concept of annular catalyst cooler (ACC) was recently proposed and validated experimentally, which showed that an internal circulation of solids can be formed by using two gas distributors and both hydrodynamics and heat transfer can be largely improved. The current work simulated the detailed hydrodynamics of gas-solids flow to advance our understanding of the ACC by using the two-fluid model.. The influence of effective particle diameter dp * and specularity coefficient in solids wall boundary condition are examined and compared with experimental data. Optimum values of dp * =170 m and =0.3 are determined and used in the simulations. The results show that by properly selecting the gas velocities and the position of heat transfer tube, internal solids circulation can be formed. TheACC has a combined hydrodynamic feature of up-and down-flow catalyst coolers with bigger solids volume fraction and smaller particle resident time, which are beneficial for improving heat transfer coefficients. Detailed hydrodynamics of gas-solids flow are obtained, and the influential parameters are examined, which provides valuable information on the design and optimization of such new ACCs.

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“…a s r s u s Cp s dx (35) where x is distance from the computational node to the heating wall, D is bed diameter.…”

Section: Numerical Simulationmentioning

confidence: 99%

Bed to wall heat transfer in supercritical water fluidized bed: Comparison with the gas–solid fluidized bed

Zhang

Dong

2015

Applied Thermal Engineering

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Study of wall-to-bed heat transfer in a bubbling fluidised bed using the kinetic theory of granular flow

Cited by 82 publications

References 39 publications

Experimental and simulation study of heat transfer in fluidized beds with heat production

Experimental and simulation study of heat transfer in fluidized beds with heat production

CFD investigation of gas-solids flow in a new fluidized catalyst cooler

Bed to wall heat transfer in supercritical water fluidized bed: Comparison with the gas–solid fluidized bed

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