真空水流窗的热特性及其节能研究

Heat transfer through the envelope is one of the major contributing factors to building energy consumption. As a novel glazing, solar absorbing water flow window is effective in reducing the energy consumption of air-conditioning and hot water systems，while daylighting can be maintained at the same time. However, its application is restricted by the low heat transfer coefficient of the double pipe heat exchanger, which makes it difficult to meet the energy saving requirement of the heating condition. Pipe-embedded wall and glazing make use of the building wall to realize heat exchange with the environments and the heat transfer area is thus enlarged, it is proven that promising energy saving can be achieved under both cooling and heating conditions. The above mentioned advantages are combined in the current project and the vacuum water flow glazing, which has one water flow chamber and one vacuum chamber, is proposed. The heat transfer performance is enhanced comparing to the solar absorbing water flow glazing because of the direct heat exchange with the environment through the window glazing, thus the energy saving requirements during both cooling and heating seasons can be met, and the vacuum chamber works as insulation. In this study, thermal characteristics will be analyzed with the CFD dynamic simulation to optimize the schematic and operating parameters in the first place. Then, Experiment will be carried out to study its energy saving performance and the dynamic behavior of the solar heat gain coefficient (SHGC). At last, numerical study on SHGC will be conducted. The implementation of the current project will promote the energy saving of cooling，heating and hot water systems and the development of green building.

围护结构传热是影响建筑能耗的一个主要因素。作为一种新型幕墙，太阳能吸热水流窗可以有效降低建筑物的空调和热水系统能耗并维持自然采光。但是其推广应用受套管换热器较低的换热效率所限制，无法满足采暖工况下的节能需求。内嵌管式墙体和窗体利用建筑立面和室内外空间换热，有效增大了换热面积，在制冷和采暖工况下均取得了很好的节能效果。本项目结合上述各技术优势而提出了真空水流窗作为幕墙，窗体包含水流腔和真空腔两个腔体。水流腔直接和室内外进行换热强化了换热效果，便于同时满足制冷和采暖工况下的节能运行需求；而真空腔起隔热作用。研究将首先利用CFD开展热工特性的动态模拟研究以完成其结构和运行参数的优化；其次，会完成其热性能的实验研究，探究其节能性和太阳得热率的动态变化规律；最后，还将开展太阳得热率的数值模拟研究。项目开展将会促进制冷、采暖和热水系统的节能以及绿色建筑的发展进程。

在我国，建筑能耗占比高达30%，而建筑物的空调和采暖等运行能耗又极大地受围护结构传热的影响。本文提出了一种新型的围护结构节能技术，真空水流窗。并从以下三个方面开展研究：包括（1）真空水流窗热工特性的CFD模拟研究；（2）真空水流窗的热性能实验研究；（3）以及真空水流窗太阳得热率的实验与数值模拟研究。.基于CFD的热工特性模拟研究发现，水流腔内流体的温度和速度分布以及水流窗的热性能会受热源大小，供水流量和温度的影响。在实际应用中应进行合理的运行参数设计，避免在空腔中形成局部涡流，以减小对换热的不利影响，从而优化换热效果。基于实验测试和数值模拟的热性能研究均发现，将真空玻璃应用于水流窗，可以有效降低通过窗体的传热并提升太阳能热利用率。相比于采用普通白玻和中空玻璃的水流窗，通过真空水流窗的室内得热量可以降低40%以上；窗体的集热效率高达25%-45%。此外，玻璃内表面温度及其波动均会大幅降低，从而有效改善室内人员的热舒适性。同样地，研究发现，真空水流窗的热性能和节能性受气象条件和供水温度等运行参数的影响。因此，有必要进行气候适应性的运行方案优化以实现不同应用条件下的节能效果最大化。此外，真空水流窗的太阳得热量要远小于常用的中空玻璃，当水流层朝外时，实验测得的太阳得热量平均值为0.172-0.1825；当水流层朝内时，太阳得热率的平均值为0.197-0.2141。这有助于降低建筑冷热负荷和空调能耗。.项目研究的开展可以为幕墙建筑的设计和节能运行提供指导。最终全面实现建筑物制冷、采暖和热水系统能耗的降低。降低建筑运行过程中的碳排放，助力我国实现“2030碳达峰和2060碳中和”的“双碳愿景”。