耦合太阳能热源的空心通风内墙蓄传热特性研究

The Qinghai-Tibet Plateau region is rich in solar energy resource, and solar air heating is significantly suitable for that region. However, the way of thermal storage is very crucial to solve the problems of unsteadiness and intermittence of solar energy. Using the traditional exterior wall for thermal storage is liable to reduce the useful heating in the room during the nighttime. The interior wall has a high capacity of thermal storage, but the heat charge and discharge of the interior wall combined with the solar heat source are not well understood, and its regulation effect on the indoor thermal environment is unclear as well. In this work, the basic research of heat transfer and thermal storage of the interior wall under complicated boundary conditions will be studied by the comprehensive methods of experimental research, theoretical analysis, and building thermal process simulation. The main work is divided into the following parts: experimental studies of thermal processes of hollow interior walls with anisotropic structures; the modeling and validation of the heat transfer processes considering the solar air collector, the ventilated hollow interior wall and the building indoor space; the heat charge and discharge characteristics of the ventilated hollow interior wall and the analysis of primary influencing factors; regulation effects of the ventilated hollow interior wall on the indoor thermal environment and the regulation methods. The research results will solve the technical problems of the combination between the interior wall thermal storage and the solar heating, and provide theory and technology for low-energy use, low-cost and maintenance-free solar energy use in residential buildings in the Plateau cold region.

青藏高原地区太阳能资源丰富，太阳能空气集热在该地区非常经济适用，但需结合合理的蓄热方式解决太阳能不稳定性和间歇性的问题。传统的外墙蓄热易降低室内夜间有效热利用率，而内墙同样具有较高的蓄热性能，但与太阳能热源耦合时的蓄放热规律掌握不足，对室内热环境的调节作用尚不清楚。本项目采用实验研究、理论分析和建筑热过程模拟相结合的方法，进行复杂边界条件下空心通风内墙蓄传热过程的基础研究。具体包括：非均质空心通风内墙结构蓄放热过程实验研究；太阳能空气集热器-空心通风内墙-建筑室内的动态传热模型构建与验证；空心通风内墙蓄放热特性及主要影响因素分析；空心通风内墙蓄放热对室内热环境的影响规律及优化调节方法。研究成果可解决内墙蓄热与太阳能供暖结合的技术难题，为高寒地区民居节能、低成本、易维护的太阳热利用提供理论基础和技术支撑。

太阳能空气集热供暖技术在青藏高原寒冷地区具有广阔的应用前景，但普通居住建筑供暖负荷白天小夜间大，且太阳能具有不稳定性和间歇性的特点，故太阳能供暖与室内供暖负荷存在明显矛盾。本项目针对青藏高原居住建筑提出太阳能空气集热器集热耦合空心通风内墙蓄放热的供暖方式，利用建筑本身内围护结构的蓄放热特性，来解决太阳能热利用的不稳定问题。项目设计并搭建了具有空心通风内墙结构的实验房，开展了不同内墙厚度和不同运行参数下的空心通风内墙传热过程实验，获得了空心通风内墙的稳态和非稳态传热规律，掌握了耦合太阳能热源的空心通风内墙蓄传热机理。通过无量纲分析建立了平板型太阳能空气集热器热性能的简化计算方法，根据ε-NTU法建立了空心通风内墙传热模型，采用RC热网络法建立了室内空气与围护结构热平衡模型，并联立构建了耦合太阳能空气集热与空心通风内墙蓄热的建筑动态传热数学模型，可用于分析太阳能空气集热器性能、空心通风内墙的蓄放热过程、室内空气温度和负荷特性。采用该模型研究了空心通风内墙的蓄放热特性及其对室内热环境的影响。建立了实验墙体的CFD数值计算模型，对空腔和墙体结构参数、集热器运行条件、非均质墙体结构等影响因素进行分析，掌握了空心通风内墙蓄传热性能的优化参数。本项目提出的空心通风内墙辐射传热量占60%以上，具有良好的辐射换热效应。相比传统的太阳能热风利用方式，耦合太阳能热源的空心通风内墙可有效提升青藏高原居住建筑夜间最低温度至13℃以上，有效改善了夜间舒适性并降低了辅助供暖能耗。本项目的研究成果对青藏高原寒冷地区的建筑节能和能源高效利用具有重要的指导意义。