全闭式热风循环密集烤房湿度调节及节能特性研究

The open moisture discharge way is adopted in current bulk curing barn. The moisture discharge waste heat losses lead to the energy inefficiency of the bulk curing barn. In addition, the moisture discharge model effects the drying quality of agricultural product. In order to explore the desiccation mechanism and facility of bulk curing barn with high energy efficiency, a closed hot air cycle bulk curing barn is proposed in this project. A condensation desiccation system with heat exchanger of heat pipe will be built. The outdoor air is adopted as a cold source for the condensation desiccation system. The thermodynamic model of the condensation desiccation system also will be developed by analyzing heat transfer and energy conversion involved in the system. The desiccation mechanism and heat transfer characteristics of the system will be clarified by numerical simulation at the same time. The desiccation and energy-saving performance of the system also will be illuminated. According to the desiccation performance of the condensation desiccation system, the key structural and operational parameters of the system will be optimized for tobacco bulk curing. The effects of operational parameters and climatic conditions on the performance of the condensation desiccation system will be investigated by experimental test. The humidity control and energy-saving characteristics will be tested and analyzed. The theoretical calculation model and test methods, which can provide supporting for the application of the closed hot air cycle bulk curing barn, will be built based on the results of numerical simulation and experimental test.

现行的密集烤房均采用开式排湿方式，一方面排湿气流余热损失大；另一方面，开式排湿方式也影响农产品的干燥质量。以此为背景，为探求高效节能、提质增效的烘烤设施及其除湿性能，本项目提出全闭式热风循环密集烤房的新思路，构建一种基于重力热管换热、以室外空气为冷源的密集烤房风冷式冷凝除湿系统。结合系统内涉及的能量转换、热质迁移过程，建立全闭式热风循环密集烤房风冷式冷凝除湿系统的热力学模型。通过数值模拟揭示该除湿系统的传热传质规律，分析其除湿与节能性能。以烟叶密集烘烤为应用实例，结合密集烤房的排湿特性，优化以室外空气为冷源的风冷式冷凝除湿系统的主要结构参数及运行参数。实验研究运行参数、气候条件对系统除湿性能的影响，分析其湿度调节及节能特性。在此基础上，基于数值模拟及实验研究结果，形成全闭式热风循环密集烤房除湿系统的理论模型和实验测试方法，为全闭式热风循环密集烤房的应用提供理论及测试依据。

为探索高效节能、提质增效的农产品烘烤设施及其除湿性能，本项目提出了一种全闭式热风循环密集烤房的新构想。基于该构想，在实验测试及理论计算分析密集烤房排湿气流露点温度、排湿余热及除湿负荷在烘烤过程中随时间的分布规律的基础上，设计了一种以室外空气为冷源的全闭式热风循环密集烤房风冷式重力热管冷凝除湿系统。结合系统内涉及的能量转换、热质迁移过程，采用k–ε 两方程模型，建立了风冷式重力热管冷凝除湿器内冷、热流体流动与换热的计算流体力学模型，数值模拟分析了风冷式重力热管除湿器的流动与换热性能。基于数值模拟优化结果，结合烟叶密集烘烤过程中排湿气流的参数，构建了风冷式重力热管冷凝除湿系统实验装置。在烟叶密集烘烤各阶段准稳态工况下，测试分析了风冷式重力热管冷凝除湿器的除湿与换热性能。测试结果表明，风冷式重力热管冷凝除湿器的析湿系数可达到2.31，显热效率随可达79.14%，潜热效率可达到45.54%。此外，在昆明烟区某烟叶密集烘烤基地改建了以室外新风为自然冷源的风冷热管冷凝除湿闭式热风循环实验密集烤房，测试分析全闭式热风循环密集烤房风冷式冷凝除湿系统湿度调节与节能性能。全闭式热风循环密集烤房重力热管除湿器的实际除湿负荷可达32.92kg/h。与现行的开式排湿密集烤房相比，全闭式热风循环密集烤房的热效率可提高6.3%-10.9%。项目的研究结果可为全闭式热风循环密集烤房的应用提供理论及测试依据。