Study of wall-to-bed heat transfer in a bubbling fluidised bed using the kinetic theory of granular flow
Study of wall-to-bed heat transfer in a bubbling fluidised bed using the kinetic theory of granular flow
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DOI：
10.1016/j.ijheatmasstransfer.2010.05.047
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发表时间：
2010-10
影响因子：
5.2
通讯作者：
L. Armstrong;S. Gu;K. Luo
中科院分区：
文献类型：
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作者：
L. Armstrong;S. Gu;K. Luo
由于流化床的复杂性，流化床传热模型的研究非常有限。颗粒流动力学理论（KTGF）已成功地应用于流体动力学模型在过去，但其应用在传热模型尚未得到广泛的测试。将KTGF应用于壁-床反应器，建立了双流体欧拉-欧拉模型。两个阻力模型，即Gidaspow和Syamlal-O 'Brien阻力模型的局部传热系数与实验数据进行了比较。此外，参数研究进行了各种系数的恢复，颗粒直径的大小和入口速度。近壁分析在稠密区和稀疏区进行。两种阻力模型都能很好地检测气泡的通过，但它们预测气泡通过传感器的完全过渡发生在略有不同的时间。与Syamlal-O 'Brien模型得到的传热系数显示更多的局部波动比Gidaspow模型，因为Syamlal-O' Brien模型是基于粒子的终端速度，这将表明一个轻微的敏感性微观尺度。扩展的模拟为一个较长的时间段，可以揭示，周期性分布发生后1.5秒和局部传热系数逐渐减少，以更好地同意与先前高估的实验结果。研究表明，鼓泡流化床在1.5 ~ 2s内就形成了规则的动态模式。
Research into heat transfer modelling in fluidised beds is very limited due to its complexity. The kinetic theory of granular flow (KTGF) has been applied successfully to hydrodynamic modelling in the past but its application in heat transfer modelling has not been tested extensively. A two-fluid Eulerian–Eulerian model has been carried out applying the KTGF to a wall-to-bed reactor. The local heat transfer coefficients are compared against experimental data for two drag models, namely the Gidaspow and the Syamlal–O’Brien drag models. Furthermore, a parametric study is carried out for a variety of coefficients of restitution, particle diameter sizes and inlet velocities. Near wall analysis is carried out in both dense and dilute regions. Both drag models detect the passage of the bubble reasonably well but they predict the complete transition of the bubble past the sensors occurs at slightly different times. The heat transfer coefficients obtained with the Syamlal–O’Brien model showed more local fluctuations than the Gidaspow model because the Syamlal–O’Brien models was developed based on the particle terminal velocities which would indicate a slight sensitivity to a microscopic scale. Extension of the simulation for a longer period makes it possible to reveal that a periodic distribution occurred after 1.5s and the local heat transfer coefficients gradually reduced to agree better with the experimental results which were previously over estimated. The study shows that a regular dynamic pattern is established in the bubbling fluidised bed only after 1.5–2s.