振动流化床宽筛分玻璃粒子与水平管局部传热特性

Local Heat Transfer Characteristic between Horizontal Heated Tube and Wide-Size Range Glass Particles in Vibrated Fluidized Bed

以宽筛分玻璃粒子为实验物料,测定了振动流化床与浸没水平加热管间的局部传热系数,研究了通气速率、振动频率和粒度分布对局部传热系数的影响。结果表明,浸没水平管局部传热系数随流化气速和振动频率的增加先增大而后逐步减小;小颗粒的存在有利于增强加热管与床层的传热;大颗粒比例的增加不利于管壁与床层的传热。由实验数据整理了预测局部传热系数的经验公式,经验公式与实验数据误差在20%以内,吻合较好。

The local heat transfer coefficients around a single horizontal heated tube immersed in the vibrated fluidized bed were investigated with wide-size range glass particles as fluidized medium. The effects of gas velocity, vibration frequency and granularity distribution on the heat transfer were studied. The results show that the local heat transfer coefficient increases firstly and then decreases with increasing the gas velocity or vibration frequency, the existence of fine particles is advantageous to enhancing the local heat transfer and the large granules are disadvantage to increasing the local heat transfer. An empirical formula was derived from the experimental data and the errors between the experimental data and the calculation are within 20%, it indicates that the agreement between them is satisfactory.