Asif Mohammad, Al-Ghurabi Ebrahim H, Fatehmulla Amanullah
Department of Chemical Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia.
Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
Nanomaterials (Basel). 2022 Jun 23;12(13):2158. doi: 10.3390/nano12132158.
Assisted fluidization techniques can significantly improve the hydrodynamics of difficult- to-fluidize solids. Among these techniques, the pulsed flow strategy is highly promising owing to its cost-effectiveness and amenability to implementation for largescale processing. Using commercial-grade, highly porous nanosilica that shows strong agglomeration behavior, we implemented the pulsed flow with square-wave pulsation schemes of 0.05, 0.10, and 0.25 Hz frequencies, and compared their effectiveness in each case. Besides the conventional approach of assessing their efficacy using the pressure drop data, we have proposed a new approach in this work that consists of computing the power of the overall pressure drop transient signals. Using the theoretical value, i.e., the effective bed weight per unit area as a reference, the percentage increase in the power was 27 ± 4, 71 ± 5, and 128 ± 4, respectively, for 0.05, 0.10, and 0.25 Hz pulsation frequencies. In fact, the average pressure drop values were substantially higher when the partial bed collapse occurred between successive pulsations when compared with the case of low-frequency pulsations. The pulsation frequency also affected the evolution of local bed dynamics in various bed regions during the expansion and collapse of the bed. Moreover, the local and global pressure transients have shown interesting mutual correlations which were otherwise not evident from their individual transient profiles.
辅助流化技术可以显著改善难流化固体的流体动力学特性。在这些技术中，脉冲流策略因其成本效益高且易于大规模加工实施而极具前景。我们使用具有强烈团聚行为的商业级高孔隙率纳米二氧化硅，实施了频率为0.05、0.10和0.25Hz的方波脉动方案的脉冲流，并比较了每种情况下它们的有效性。除了使用压降数据评估其功效的传统方法外，我们在这项工作中还提出了一种新方法，该方法包括计算总压降瞬态信号的功率。以理论值，即单位面积的有效床重为参考，对于0.05、0.10和0.25Hz的脉动频率，功率的百分比增加分别为27±4、71±5和128±4。实际上，与低频脉动情况相比，当连续脉动之间发生部分床层坍塌时，平均压降值要高得多。脉动频率还影响了床层膨胀和坍塌过程中各个床层区域局部床层动力学的演变。此外，局部和全局压力瞬变显示出有趣的相互关联，而从它们各自的瞬态曲线中则不明显。
