Due to the presence of liquid bridge forces, wet particles reveal totally different fluidization behaviours than dry fluidized beds. This paper studies the bubble dynamics of wet Geldart-D particles in a wet 2D fluidized bed. A digital image analysis method is adopted to identify bubbles and extract bubble properties based on MATLAB software. During fluidization, the bubble feature analysis of optimized binary images captures the bubble size variation, bubble fraction, and bubble shape. The results show that the increasing liquid saturation promotes the gas holding capacity of the emulsion phase, leading to the decreasing bubble fraction. When the particle size grows, the stability of the emulsion phase is promoted and hence the average bubble diameter increases. As the liquid saturation increases, the enhancing liquid bridge forces limit the bubble growth and promote the bubble breakage, which contributes to the small bubbles. With respect to the wet particles, of which the diameter is 1 mm and the liquid saturation is over 15%, slugging is likely to be observed, resulting in the increasing equivalent bubble diameter. The growing liquid saturation increases the wide aspect ratio, decreases the shape factor, and disperses the dependence between the two parameters. This indicates that small and irregular bubbles are likely to be seen in wet fluidized beds.

中文翻译：

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使用数字图像分析法研究湿流化床中的气泡行为

由于液桥力的存在，湿颗粒表现出与干流化床完全不同的流化行为。本文研究湿二维流化床中湿 Geldart-D 颗粒的气泡动力学。采用基于MATLAB软件的数字图像分析方法识别气泡并提取气泡特性。在流化过程中，优化二值图像的气泡特征分析捕获气泡尺寸变化、气泡分数和气泡形状。结果表明，液体饱和度的增加促进了乳液相的持气能力，导致气泡分数降低。当粒径增大时，乳液相的稳定性得到提高，因此平均气泡直径增大。随着液体饱和度的增加，增强的液桥力限制了气泡的生长并促进了气泡的破裂，这有助于形成小气泡。对于直径为 1 mm 且液体饱和度超过 15% 的湿颗粒，很可能会出现段击现象，导致当量气泡直径增大。不断增长的液体饱和度增加了宽纵横比，降低了形状因子，并分散了两个参数之间的依赖性。这表明在湿流化床中可能会看到小的和不规则的气泡。不断增长的液体饱和度增加了宽纵横比，降低了形状因子，并分散了两个参数之间的依赖性。这表明在湿流化床中可能会看到小的和不规则的气泡。不断增长的液体饱和度增加了宽纵横比，降低了形状因子，并分散了两个参数之间的依赖性。这表明在湿流化床中可能会看到小的和不规则的气泡。