Three dimensional models of porosity and airflow resistance in stored grain bulks

谷物的通风干燥过程由于受天气的影响，总是有失败的风险。仓储谷物中的堆积、粉尘和异物(DFF)的存在进一步加剧了这一问题，因为仓储粮食中的DFF会堵塞谷物粒之间的空气空间，导致气流阻力不均匀。气流不均匀会导致谷物在高气流位置过度干燥，而在同一仓内的低气流位置导致湿(变质)谷物。影响气流阻力分布的两个主要因素是颗粒之间的孔结构(大小、形状、连通性、孔的曲折性和孔与气流方向的取向)和流体的性质(空气速度和粘度)。储粮的颗粒类型(粒的大小和形状)以及DFF的量和大小直接影响到孔结构。孔隙度与料仓内的孔结构和气流阻力密切相关。目前还没有考虑散装谷物内部Dff分布(大小和百分比)的气流阻力模型，这导致了这一领域的知识空白。我的研究计划的长期目标是对储藏谷物生态系统的物理和生物行为进行数学建模。在接下来的5年里，我将专注于通过开发储存粮堆内的3D有限元气流阻力模型来填补这一空白，并考虑DFF(尺寸和百分比)对孔隙率和气流阻力的影响。为了开发和验证这些模型，我建议量化孔隙率、DFF尺寸分布、气流方向、气流速度和气流阻力之间的关系。拟议的实验将使用新技术来表征孔结构和测量空气流动阻力分布。这一研究结果不仅有助于了解散装颗粒的孔结构和流动的基础知识，而且为散装固体储存系统的设计和运行提供了合理的分析工具。开发的气流阻力分配模型将帮助设计工程师优化通风系统的布局，并帮助谷物所有者进行最佳的谷物干燥和通风，从而避免质量和数量的损失，并保持加拿大作为一个声誉良好、可靠和始终如一的优质谷物生产国的国际声誉。两名硕士、一名博士和三名本科生将通过这一拟议的计划接受培训。将制定个性化的培训计划和方法。通过在EDI(公平、多样性和包容性)环境下进行这种严格的培训，所有学生都将接受先进的仓储粮食管理培训，并为未来的职业生涯做好准备。他们还将在粮食仓储管理的重要领域提高技术技能。

The grain aeration and drying process is always at risk of failure because of its weather dependency. The presence of dockage, fines, and foreign materials (DFF) in stored grain exacerbates this issue further because the DFF in stored grain can plug the air space among grain kernels, causing uneven airflow resistance. The nonuniform airflow results in overdried grain at high airflow locations and wet (spoiled) grain at low airflow locations inside the same bin. The two major factors influencing the airflow resistance distribution are the pore structure among grain kernels (size, shape, connectivity, tortuosity of the pores, and orientation of the pore to the airflow direction) and properties of fluids (air velocity and viscosity). The pore structure is directly influenced by grain types (kernel size and shape) of the stored grain and amount and size of DFF. Porosity is strongly related to pore structure and airflow resistance in a bin. No model of airflow resistance considering the distribution of DFF (both in size and percentage) inside grain bulks has yet been developed, leading to a knowledge gap in this area. The long-term goal of my research program is to mathematically model the physical and biological behaviours of stored grain ecosystems. In the next 5 years, I will focus on objectives to fill this gap by developing 3D finite element airflow resistance models inside stored grain bulks and considering the effect of DFF (both size and percentage) on porosity and airflow resistance. To develop and validate these models, I propose to quantify the relationship among porosity, DFF size distribution, airflow direction, airflow velocity, and airflow resistance. The proposed experiments will use novel technique to characterize pore structures and measure air flow resistance distribution. The results from this research will not only contribute to the fundamental knowledge of pore structure and flow through grain bulks, but also provide a rational analysis tool for the design and operation of bulk solid storage systems. The developed airflow resistance distribution models will help design engineers to lay out the aeration system optimally and grain owners to conduct a optimal grain drying and aeration, so quality and quantity losses can be avoid and Canada's international reputation as a reputable, reliable, and consistent producer of high-quality grain can be maintained. Two MSc, 1 PhD, and 3 undergraduate students will be trained through this proposed program. An individualized training plan and approach will be developed. Through this rigorous training under an EDI (equity, diversity, and inclusion) environment, all students will be trained on the advanced management of stored grain and be prepared to become independent for their future careers. They will also advance their technical skills in areas important to grain storage management.