Cheng Qian, Liu Zihui, Sun Jiayi, Li Shuo, Zhao Chongxuan, Su Junfeng, Liu Qingyu, Xin Mingjin, Liu Dejun
College of Engineering, Shenyang Agricultural University, Shenyang, 110866, China.
Heliyon. 2024 Apr 30;10(9):e30399. doi: 10.1016/j.heliyon.2024.e30399. eCollection 2024 May 15.
As a new type of agricultural waste block substrate utilization, the initial wet base state of the substrate culture block needs to be dried. Therefore, studying the drying mechanism of substrate culture block is critical. In this study, the substrate culture block in a dry state was taken as the research object. Based on physical and chemical properties, the internal section of the substrate culture block was characterized by scanning electron microscopy and the pore condition of the particles was quantified. The results showed that the internal pore structure was uniform and favorable for plant root growth. Based on the pore structure, pore channel modeling was constructed to investigate the distribution of the internal multiphase medium and to distinguish between channels and pore-blind channels. The applicability of the modeling was verified and discussed. By measuring the drying rate of the substrate culture block and classifying its drying stages as fast speed, constant speed, and slow speed, it is clarified that the forms of moisture existence are bound-state water and free-state water, and the moisture migration is prioritized as surface adsorption water, interparticle water, particle attached water, and capillary water. Innovate a method to quantify the change of pore space in the drying process by pore coefficient ratio to evaluate the drying quality. The results show that when the pore coefficient ratio is about 40 %, its moisture content is 20 %∼30 %, and the drying effect is best at this time. The physical drying test further confirmed the correctness of the conclusion of the drying stage division and water loss law. This study can provide a theoretical reference for the modeling study of the pore structure of the block matrix and the exploration of its drying mechanism.
作为一种新型的农业废弃物块状基质利用方式，基质栽培块的初始湿基状态需要进行干燥处理。因此，研究基质栽培块的干燥机理至关重要。本研究以干燥状态下的基质栽培块为研究对象。基于物理和化学性质，利用扫描电子显微镜对基质栽培块的内部截面进行表征，并对颗粒的孔隙状况进行量化。结果表明，内部孔隙结构均匀，有利于植物根系生长。基于孔隙结构，构建孔隙通道模型，研究内部多相介质的分布，区分通道和盲孔通道，并对模型的适用性进行了验证和讨论。通过测定基质栽培块的干燥速率，将其干燥阶段分为快速、恒速和慢速阶段，明确了水分存在形式为束缚态水和自由态水，水分迁移优先顺序为表面吸附水、颗粒间水、颗粒附着水和毛细水。创新了一种通过孔隙系数比量化干燥过程中孔隙空间变化的方法，以评价干燥质量。结果表明，当孔隙系数比约为40%时，其含水率为20%∼30%，此时干燥效果最佳。物理干燥试验进一步证实了干燥阶段划分和水分损失规律结论的正确性。本研究可为块状基质孔隙结构的建模研究及其干燥机理的探索提供理论参考。
