Wang Fei, Tian Nan, Ren Lei, Zhang Kai, Wang Jing, Zhang Yuanyuan
Engineering Research Center of Ministry of Education for Resource Efficiency Enhancing and Carbon Emission Reduction in Yellow River Basin Shanxi University, Taiyuan, 030006, Shanxi, China.
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China.
Sci Rep. 2025 Apr 2;15(1):11308. doi: 10.1038/s41598-025-95646-y.
Moisture migration during the microwave drying process of coal slime is critical for improving drying efficiency and reducing energy consumption. Nevertheless, current methods for quantifying these migration behaviors remain insufficient. In this research, we employed a comprehensive approach that combines experimental investigations with multi-physical field simulations to quantitatively characterize the distribution and state of moisture within coal slime dough at different locations during microwave drying. The entire drying process was divided into three distinct stages based on temperature distribution: preheating, constant temperature, and reheating. During the preheating stage, as temperature rose, more than 74.1% of the initial water content within the central region of the slime dough underwent vaporization. creating a pressure gradient between the interior and exterior of the coal slime dough. In the subsequent constant temperature stage, over 45.5% of the remaining water content within the slime dough was driven to the surface by the pressure gradient, where it vaporized and diffused into the surrounding atmosphere. During the reheating stage, moisture was initially vaporized as steam and subsequently diffused into the atmosphere through inter-particle voids, due to the inherent difficulty in forming a continuous liquid bridge between particles at this stage. Furthermore, we examined the influence of particle size and dough diameter of coal slime on moisture migration and diffusion during microwave drying, thereby substantiating the diffusion mechanism. By integrating experimental and simulation data, this study provides a detailed understanding of the moisture migration mechanisms within coal slime dough during microwave drying. These findings are valuable for the design of efficient microwave drying technologies, particularly for drying materials with high-water content and viscosity, such as typical coal slimes and sewage sludge.
煤泥微波干燥过程中的水分迁移对于提高干燥效率和降低能耗至关重要。然而，目前量化这些迁移行为的方法仍然不足。在本研究中，我们采用了一种综合方法，将实验研究与多物理场模拟相结合，以定量表征微波干燥过程中不同位置煤泥团内水分的分布和状态。根据温度分布，整个干燥过程分为三个不同阶段：预热、恒温、再加热。在预热阶段，随着温度升高，煤泥团中心区域超过74.1%的初始含水量发生汽化，在煤泥团内部和外部之间形成压力梯度。在随后的恒温阶段，煤泥团内剩余含水量的45.5%以上被压力梯度驱动到表面，在那里汽化并扩散到周围大气中。在再加热阶段，由于在此阶段颗粒之间难以形成连续的液桥，水分最初以蒸汽形式汽化，随后通过颗粒间空隙扩散到大气中。此外，我们研究了煤泥颗粒尺寸和煤泥团直径对微波干燥过程中水分迁移和扩散的影响，从而证实了扩散机制。通过整合实验和模拟数据，本研究详细了解了微波干燥过程中煤泥团内的水分迁移机制。这些发现对于高效微波干燥技术的设计具有重要价值，特别是对于干燥高含水量和高粘度的材料，如典型的煤泥和污水污泥。
