Study on the theory of the mechanism of heat transportation within fine particle powder through the short-term contact

本研究的目的是确定细颗粒流化床内的传热机理，以便利用流化床内的高传热性能来高响应地控制粉末层的温度。建立了细粉流化床内传热的数值模拟模型。在模拟中，将细粉注入由直径为1 mm的玻璃珠和作为流化流体的气流构成的流化床中。采用弹性-固体-碰撞模型建立了数值模型，研究了微尺度传热机理。将大范围控制参数的数值模拟结果与实验结果进行比较，验证了本模拟的有效性。实验和数值模拟结果表明，随着粉末喷射速率的增加，粉末倾向于留在主流化床内，在主流化床上方形成另一个流化床。从热传递的角度阐明了存在适当的细粉喷吹速率。确定了细粉流化床内的传热机理，并确定了利用流化床控制粉层温度的最佳操作条件。

The purpose of the present study is to determine the mechanism of heat transportation within the fine particle fluidized bed in order to utilize the high performance of heat transfer within the fluidized bed to the temperature control of the powder layer in high response. The establishment of numerical simulation model for the heat transfer within the fluidized bed with fine particle powder has been performed. In the simulation/fine powder was injected into the fluidized bed that was constructed of glass beads with 1 mm in diameter and airflow as fluidizing fluid. The numerical model was constructed using elastic-solid-collide model to investigate the micro-scale heat transfer mechanism. The results of numerical simulation for the wide range of dominating parameter were compared with that of experimental results to confirm the validity of the present simulation. From the experiment and numerical simulation, the powder tends to be kept within the main fluidized bed to form anotherfluidized bed above the main one with an increase in the injection rate of powder. It was elucidated that there was appropriate injection rate of fine powder from the viewpoint of heat transportation. The mechanism of heat transfer within the fluidized bed with fine powder has been determined and the optimum operation conditions for the utilization of fluidized bed to the temperature control of powder layer were extensively determined.