菌类植物对流干燥过程中非线性形变与热质传递耦合机理的理论及实验研究

Fungus-plants are water-wet porous media, whose convective drying process is a complicate physical process including both the shrinkage deformation and the heat/mass transfer. The final drying quality, drying efficiency and energy consumption are closely related to the drying characteristics. Because the systematic studies are still absent now, in this project, we aim to study the drying process of mushroom which is one of the most common fungus-plants by using experimental measurements, theoretical analysis and numerical simulations. The models of effective thermal conductivity, moisture diffusivity and strain-stress relation will be developed. The influence of drying conditions such as the temperature, humidity, velocity and pressure of hot air on the drying characteristics during different drying stages will be investigated. We will also study the non-linear strain-stress relation, temperature distribution, moisture distribution inside the mushrooms together with the effect of shrinkage deformation on heat and moisture transport. Then, the multi-physical model considering temperature distribution, pressure distribution, velocity, moisture distribution and stress distribution will be developed, which will be used to predict the drying characteristics of mushrooms. Our work can be used to design and optimize the drying process. The proposed project, integrating of material science, computer graphics, heat and mass transfer, and test technology, is a multidisciplinary research, and has academic significance and great value in engineering.

菌类植物是含湿多孔介质，其对流干燥过程是一个包括收缩变形和传热传质的复杂物理过程，并且干燥物品质、干燥效率和能源消耗与菌类植物的干燥特性密切相关，目前仍缺乏系统的理论研究。本项目以香菇为研究对象，采用实验测试、理论分析和数值模拟相结合的研究方法，构建香菇的等效热导率、湿分扩散率和应力应变模型，探讨外部干燥条件（热空气温度、湿度、流速和压力等）对香菇在不同干燥阶段内的干燥特性的影响，重点分析对流干燥过程中香菇的非线性应力应变特性和香菇内部温度和湿分分布及热量和湿分输运特性随收缩变形的变化规律；在此基础上建立香菇内部包括温度场、压力场、速度场、湿分场和应力场等多模式耦合的香菇干燥特性的预测模型，为干燥过程控制和干燥工艺优化提供理论支撑。本项目融合材料学、计算机图形学、传热传质学、测试技术等领域，属于多学科交叉研究，具有重要的学术意义和工程应用价值。

干燥是农产品加工业的重要基础工艺技术。开发高效节能的先进干燥技术，是促进农业现代化的重要课题。本项目研究了菌类植物对流干燥过程中的“热-湿-力”耦合机理，探索了包含非线性收缩变形在内的干燥传热传质模式，建立了多场耦合的干燥过程预测模型，研究了多种干燥工艺对菌类植物干燥特性的影响。本项目按照计划顺利完成了研究内容，达成了预期目标，取得了以下三项主要研究成果。（1）构建了菌类植物热量和湿分传输能力相关的热物性参数（等效热导率和渗透率）的预测模型，该模型能够全面考虑热空气温度、湿度、流速、湿分含量和孔隙结构变化对菌类植物内部热湿输运特性的影响；（2）完成了热风干燥过程中菌类植物的干燥特性和收缩变形的实验测试，探讨了外部干燥条件（热风温度、风速等）对菌类植物干燥特性的影响；（3）开发了对流干燥条件下菌类植物内部 “热-湿-力”耦合的数值模型，明晰了菌类干燥特性与干燥条件之间的内在联系。本项目揭示了菌类植物对流干燥过程的“热-湿-力”多场耦合机理，为菌类植物干燥工艺优化提供重要的数据和理论支撑，对农产品高效干燥技术的发展和应用具有一定的指导作用。