相变蓄能多层多热桥墙体双向四维全周期热湿耦合传递机理研究

The heat-moisture transfer process in the phase change material wall is extremely complicated, owing to the two-way heat transfer, phase change process, as well as the whole life cycle of the wall. Studies on the phase change material wall usually focus on the thermal performance, such as the surface temperature distribution and the heat transfer rate, as well as thickness of the wall and the characteristics of the phase change materials. But few studies were found to be related to effects of the heat-moisture bridge on the heat storage capacity, and the heat and moisture transfer of the wall. This project focuses on the reasonable construction form, two-way heat and moisture transfer process, and the effects of the heat-moisture bridge on the energy storage and heat transfer characteristics of the phase-change material wall under different climatic conditions during its whole life cycle. According to the results, the reasonable construction form of phase change material wall suitable for different climate conditions could be determined. And the effects of the phase change process, construction form, heat-moisture bridges, time-varying characteristics of air temperature and humidity on the performance of the wall could also be clarified, based on which the two-way and four-dimensional mathematical model of the coupling heat and humidity transfer of the wall for the whole life cycle was established. Findings of this project are of great theoretical significance and practical value for enriching and developing the mathematical model of wall heat and moisture coupling transfer under multi factors, also reducing building energy consumption and promoting sustainable development of construction industry.

综合考虑双向传热相变吸放热过程和全周期等因素，相变蓄能墙体内部热湿传递过程非常复杂。目前针对其研究主要集中在墙体的一些普通热工性能上，如墙体温度分布与壁面热流量的变化，以及相变材料类型与墙体的厚度等方面，没有针对热湿桥对相变蓄能墙体的蓄能能力、热湿传递影响综合起来进行研究。本项目拟根据不同气候条件，对相变蓄能墙体的合理构造形式，双向热湿传递过程，以及全周期内热湿桥对墙体蓄能和传热性质进行研究，从而提出适合不同气候条件的蓄能墙体合理构造形式，并探讨相变过程、墙体构造、热湿桥效应、温湿度时变特征等因素对蓄能墙体的影响，建立全周期、双向、四维热湿耦合数学模型，从而揭示其热湿耦合传递规律。本项目的研究对丰富和发展多因素条件下墙体热湿耦合传递数学模型，降低建筑能耗，从而推动建筑业可持续发展具有重要的理论意义和实用价值。

相变蓄能墙体是实现节能减排的重要举措，综合考虑双向传热相变吸放热过程和全周期等因素，以及热湿传递影响对墙体保温效果的影响是相变墙体研究中的关键问题。本项目通过对相变墙体热湿传递过程进行理论分析，建立了适应夏热冬冷地区气候的双层相变墙体模型；通过数值仿真优选出适应夏季和冬季填充在墙体里材料的两种相变温度，并以夏热冬冷地区典型城市——衡阳的气象参数为依据，通过数值模拟以及实验测试综合分析了相变墙体传热传湿特性与效果；对比分析了东西南北不同朝向的双层相变墙在冬夏季节的保温隔热效果；研究了相变墙体在传热周期内动态双向传热过程，并将其进行了可视化；对比研究了装配式框架式相变墙体结构在不同保温方式下出现的热桥问题，同时通过对墙体进行力学性能实验测试，确定了相变材料的最佳掺比。. 研究表明，夏热冬冷地区双层相变墙体夏季适应相变温度区间为28-29℃，冬季适应相变温度区间为16-17℃，不同朝向表现出不同的保温隔热效果，其中夏季西墙和冬季东墙相变墙体表现的调温性能优于其他朝向墙体，西墙在夏季受热最剧烈因此需要更高的相变温度的材料。夏季和冬季各朝向相变墙体壁面温度衰减作用和延迟时间明显，能有效降低建筑能耗。此外，墙体外保温效果最好，外保温装配式框架剪力墙结构内表面温度稳定，无热桥现象出现。考虑热湿耦合传递，减缓了室内温度变化速率，同时也有效减小了湿度波动程度，相变材料的存在在一定程度上影响墙体内部热传递和湿传递过程。. 项目研究成果进一步揭示了墙体与建筑热湿耦合传递规律，对降低建筑围护结构的整体能耗、保障建筑可持续发展具有重要的理论意义与应用价值，同时，本研究响应国家双碳目标发展战略需求，可指导和规范夏热冬冷地区相变围护结构的应用开发，具有一定的经济效益和社会效益。