遮阳翻板辐射传输机理及辐射-对流换热动态特性研究

Louver shades can effectively block the solar radiation, is widely used in energy saving buildings to minimize solar heat gain in summer, but the existing model could not accurately and objectively reflect solar radiation transfer and heat transfer mechanism between shades and building envelope . Existing solar radiation transfer model makes too many simplifying assumptions, and could not be used to calculate the radiation transfer of louvers with a certain shape and thickness; Boundary conditions of radiative-convective heat transfer failed to consider the.influence of solar radiation heat gain. The project will focus on radiation transfer mechanism and heat transfer mechanism between shades and building envelope through theoretical and experimental study, the objective mechanism model of radiation transfer and radiative-convective heat transfer between shades and building envelope will be established. Heat transfer law of microenvironment between shades and building envelope will be studied. The study contents include: 1) Study solar radiation transmission mechanism of louvers, and establish.calculating model of solar radiation transfer; 2) Verify solar radiation transfer model based on the experiment 3) Conduct the numerical simulation and experimental study on radiative-convective heat transfer between shades and building envelope to obtain empirical correlations of heat transfer 4) Based on models and empirical correlations above, study the radiative-convective heat transfer characteristics under different boundary conditions , to obtain the performance of louver shades in the whole year, and validate the results by field test.

遮阳翻板能有效阻挡太阳辐射，被广泛应用于节能建筑以减小夏季太阳辐射得热，但是现有计算模型难以准确、客观地反映遮阳翻板与围护结构之间的辐射传输及换热机理。现有辐射传输模型对翻板做了太多的简化假设，无法用于有一定形状、厚度的翻板的辐射换热计算；辐射-对流换热计算没能考虑太阳辐射得热的影响。本课题将围绕翻板辐射传输及其与围护结构间换热的问题展开机理研究与实验研究，建立能够客观描述遮阳翻板与围护结构间辐射传输以及辐射-对流换热的机理模型，研究遮阳与建筑围护的动态换热规律。研究内容：1）研究翻板的太阳辐射传输机理，建立翻板太阳辐射传输的计算模型；2）搭建太阳辐射模拟测试平台，实验验证辐射传输模型；3）进行遮阳板与围护结构间辐射-对流换热的数值模拟和实验研究，并得到相应的换热计算经验关联式 4）研究不同边界条件下的遮阳翻板与围护结构之间辐射-对流换热规律，得到遮阳翻板全年运行特性，并通过实验验证。

夏热冬暖地区和夏热冬冷地区的太阳辐射带来的建筑得热量占围护结构得热的比例较高，使用合适的遮阳设施能有效地降低建筑的太阳辐射得热，遮阳翻板由于遮阳调光效果好、结构强度高、传动机构稳定等优点而被推广应用。但是遮阳翻板结构复杂，辐射传输计算及对流换热机理有其自身的特点和较高的难度，导致难以准确测算其对建筑物空调能耗的影响。.本研究着重于研究遮阳翻板太阳辐射传输机理，推导了遮阳翻板直接透射的解析解，并建立了辐射传输计算的数学模型，开发遮阳翻板有效光学特性的计算程序；新的太阳辐射传输计算模型克服了传统模型“平板假设”和“漫反射假设”的缺陷，能客观反映各种翻板的形状、表面光学参数等带来的影响。.并在太阳辐射传输机理研究基础上，研究翻板与围护结构之间辐射-对流综合换热动态特性。编制了遮阳围护结构系统传热计算程序。遮阳翻板围护结构系统传热计算程序考虑了遮阳翻板的形状、光学参数、倾角等带来的影响，并能独立分析翻板对遮阳窗口和遮阳墙体得热的影响。搭建了遮阳围护结构系统传热模型的验证实验台验证传热计算程序的正确性。.本研究提出的辐射传输模型计算精度可提高5%以上，遮阳翻板围护结构系统传热计算程序准确率较高。研究结果可为建筑能耗模拟计算提供更精确的计算模型和计算程序支撑。