Temperature Visualization of Fluidizing Particles and Construction of a Heat Transfer Model in a Fluidizing Bed Heat Exchanger.

本研究从微观层面探讨了传热机理。气固流化床中的有效传热机理之一--流化颗粒与传热面接触时的热传导进行了实验研究。在接触期间流化颗粒的温度借助于红外成像仪可视化。该可视化显示，颗粒在接触之前在传热表面上的热边界层中已经被显著加热。基于颗粒的可视化温度，通过反分析来估计流化颗粒与传热表面之间的接触传导，并且使用所估计的接触传导，为了评价实际流化床中常见的管式换热表面的导热贡献，床，传热实验，使用两种类型的球形颗粒的有效性进行评估。实验中使用的这些颗粒由玻璃和铝制成，直径相同。由于颗粒具有几乎相同的密度，但不同的导热系数，总传热的差异被认为是对应于传导传热的贡献。对于相同的传热表面的可视化估计的贡献是在良好的协议与可视化估计。使用这两种类型的颗粒，在不同的流化条件下，管型传热表面上的传导传热的贡献进行了评估。

This study deals with the heat transfer mechanisms at a microscopic level. Heat conduction during contact between a heat transfer surface and fluidizing particles, which is one of the effective heat transfer mechanisms in a gas-solid fluidized bed, has been empirically investigated. The temperatures of the fluidizing particles during the contact period is visualized with the aid of an infrared imager. This visualization reveals that the particles have been considerably heated in the thermal boundary layer on the heat transfer surface before contact. Based on the visualized temperature of the particles, the contact conductance between a fluidizing particle and the heat transfer surface is estimated by inverse analysis, and using the evaluated contact conductance, the contributions of the conductive heat transfer to the total heat transfer are also evaluated.In order to evaluate the contributions of the conductive heat transfer to a tube type heat transfer surface that is popular in practical fluidized beds, the validity of a heat transfer experiment that uses two types of spherical particles is evaluated. These particles used in the experiment are made of glass and aluminum and have the same diameter. Since the particles have almost the same density but deferent thermal conductivity, the deference of the total heat transfer is considered to correspond to the contributions of the conductive heat transfer. The contributions estimated for the same heat transfer surface as the visualization are in good agreement with those estimated by the visualization. Using the two types of particles, the contributions of the conductive heat transfer on a tube-type heat transfer surface are evaluated in a various fluidizing conditions.