王 帅1，2，金捍宇1，刘 江1，2，王家兴1，3
1. 哈尔滨工业大学 能源科学与工程学院，黑龙江 哈尔滨 150001；2. 哈尔滨工业大学 郑州研究院，河南 郑州 450000；3. 烟台龙源电力技术股份有限公司，山东 烟台 264006
王帅，金捍宇，刘江，等. 脉动气流作用下非球形湿颗粒流化干燥特性［J］. 中国粉体技术，2025，31（6）：1-9.
WANG Shuai， JIN Hanyu， LIU Jiang， et al. Fluidized drying characteristics of non-spherical wet particles under pulsating airflows［J］. China Powder Science and Technology，2025，31（6）：1−9.
DOI：10.13732/j.issn.1008-5548.2025.06.010
收稿日期：2025-05-06，修回日期：2025-09-18，上线日期：2025-10-13。
基金项目：国家自然科学基金项目，编号： U20A20304。
第一作者简介：王帅（1985—），男，教授，博士，博士生导师，黑龙江优秀青年基金获得者，研究方向为流态化与催化颗粒性能表征。E-mail：shuaiwang@hit. edu. cn。
摘要：【目的】探究脉动气流作用下非球形湿颗粒流化干燥过程中的热质传递特性，实现对非球形湿颗粒流化干燥过程的调控。【方法】采用计算流体力学-离散单元法，考虑非球形湿颗粒干燥过程引起的颗粒间液桥力变化以及颗粒间碰撞过程中的液体迁移，同时考虑湿颗粒干燥过程中液桥对热量传递的贡献以及气相中水蒸气含量的变化，构建非球形湿颗粒流动-热质传递模型，研究喷动床干燥器中非球形湿颗粒热质传递的演化规律；引入正弦波、矩形波脉动气流，分别分析正弦波、矩形波脉动气流对非球形湿颗粒流化干燥行为的影响。【结果】相较于矩形波脉动气流，正弦波脉动气流改善非球形湿颗粒流化干燥的效果更佳，可以提高干燥过程中传热传质的均匀性。【结论】引入正弦波脉动气流对于非球形湿颗粒流化干燥具有改善作用。
Objective The study aims to investigate the heat and mass transfer characteristics of fluidized bed drying under pulsating airflow and to regulate the drying process of non-spherical wet particles.
Methods Numerical simulations were conducted to study the fluidized bed drying process of non-spherical wet particles. The computational fluid dynamics-discrete element method (CFD-DEM) was employed to characterize the gas-particle flow and mass/heat transfer behaviors. To achieve an accurate characterization of non-spherical wet particles, a flow-heat/mass transfer model was developed considering the variations in inter-particle liquid bridge forces. In this model, the equivalent radius at the contact position was used in place of the particle radius when calculating liquid bridge forces. Liquid migration during particle collisions was also incorporated, along with the influence of liquid bridges on heat transfer and variations in gas-phase water vapor concentration during drying. The evolution of heat and mass transfer for non-spherical wet particles in a spouted bed dryer was studied， and the influence of sinusoidal and rectangular wave-shaped pulsating airflows on fluidized bed drying behavior was analyzed.
Results and Discussion The proposed model was validated against experimental data. The results showed that, as drying progressed, the liquid content of particles gradually decreased and particle agglomeration weakened. Compared to non-pulsating airflow, pulsating airflow significantly increased the drying rate, resulting in a smaller drying dead zone. Under rectangular wave-shaped pulsating airflow, particles in the annular region were difficult to fluidize, leading to a larger dead zone compared to sinusoidal waveform. The total pressure drop under the rectangular wave-shaped pulsating airflow was lower than that under sinusoidal wave-shaped pulsating airflow. As drying continued, more particles participated in fluidization under sinusoidal wave-shaped pulsating airflow, whereas the rectangular wave-shaped pulsating airflow showed no significant improvement in fluidization. Compared to sinusoidal wave-shaped pulsating airflow, rectangular wave-shaped pulsating airflow exhibited a slower particle heating rate, and in the later stage of drying, a larger standard deviation of particle temperature in the bed indicated relatively weaker and more heterogeneous heat transfer between gas and particles. In contrast, sinusoidal wave-shaped pulsating airflow demonstrated higher heat transfer efficiency, with a more uniform temporal and spatial distribution of gas-particle heat transfer. Rectangular wave-shaped pulsation exhibited lower heat transfer via liquid bridges and wet particle contact. Notably, dry particle contact conduction emerged earlier in the spouted bed under rectangular wave-shaped pulsating airflow, indicating premature complete drying of some non-spherical wet particles. The drying rate and its standard deviation evolved differently over time under pulsating airflows of different waveforms. Specifically, the drying rate under rectangular wave-shaped pulsating airflow declined earlier due to insufficient gas-particle contact for certain particles in the later drying stage, which reduced the overall drying rate in the bed.
Conclusion The introduction of pulsating airflow improves flow behavior in the spouted bed dryer to a certain extent, reduces fluidization dead zones in the annular region, accelerates the drying process, and improves the drying uniformity. During particle heat transfer, wet particle contact heat conduction plays a dominant role. As drying progresses, the volume of liquid bridges decreases continuously, thereby weakening heat conduction. Compared to sinusoidal wave-shaped pulsating airflow, rectangular wave-shaped pulsed airflow causes some particles to dry completely at an earlier stage. In contrast, sinusoidal wave-shaped pulsating airflow more effectively enhances the fluidized drying of non-spherical wet particles, improving both heat and mass transfer efficiency and overall drying uniformity.
Keywords：fluidized bed; pulsating airflow; drying; heat and mass transfer
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