围护结构湿迁移对室内热环境及空调负荷影响关系研究

发布时间：2019-02-24 16:20

【摘要】：准确掌握建筑冷热负荷是节能分析、暖通系统设计和运行控制的基础。建筑冷热负荷主要通过围护结构内表面的热流体现，而该热流又与围护结构内部及表面的热湿迁移过程有关。目前相关设计规范和负荷分析软件大多建立在传热理论基础上，虽有学者对围护结构内部热湿耦合迁移机理和室内空气中的湿迁移过程进行了深入研究，但关于围护结构内部湿传递和表面湿迁移对负荷的影响关系尚少见报道。我国地域辽阔，，热湿气候多样，忽略围护结构湿迁移必然会对室内热环境及建筑冷热负荷分析造成不同程度的误差。 针对现有负荷计算方法难以体现围护结构湿迁移对其影响的情况，本文综合利用理论分析、验证分析、数值计算和现场测试的方法，研究了围护结构湿迁移对室内热环境和建筑冷热负荷的定量影响关系。 通过对围护结构热湿迁移机理分析，建立了完善的围护结构热湿耦合传递及内表面热湿迁移数学模型；针对以往围护结构传热传质系数的恒值设定，难以反映该系数随环境变化的情况，通过研究获得了传热传质系数随温度和湿度变化的函数关系。 针对围护结构热湿耦合传递非线性控制方程，利用COMSOL Multiphysics软件中的系数型偏微分方程模块进行了编程求解，分析了多种边界条件下考虑与未考虑墙体湿迁移情况下，墙体内表面温度及热流的差异特性，获得了墙体传湿对传热过程的影响关系。研究发现：考虑传湿与不考虑传湿相比，不同材料墙体内表面温度的降低值：松木板墙，0.1℃～1.4℃；混凝土墙，0～0.2℃；多孔砖墙，0.1℃～0.7℃。考虑传湿时墙体内表面的潜热换热量占壁体总传热量的比值：松木板墙：12%～73%；混凝土墙：0～8%；多孔砖墙：9%～36%。 在分析墙体湿迁移对传热过程影响的基础上，结合围护结构热湿耦合传递过程计算程序，利用MATLAB对整体房间热湿环境分析方程组进行了编程计算，分析了围护结构湿迁移对内表面温度及室内热环境的影响关系；考虑到墙体含湿量差异，分别对4种墙体含湿量不同的建筑内表面温度和室内空气热湿状态进行了现场测试，分析了墙体含湿及湿传递对室内热环境的影响。结果表明，夏季空调期，墙体内表面的湿迁移作用可明显降低墙体内表面温度，进而降低平均辐射温度，在同等热舒适条件下，可以减少空调负荷或使用时间；墙体内表面的吸放湿过程对室内湿环境的调节作用随室外相对湿度幅度的增大而明显，而对室内空气温度的影响较小；考虑墙体传湿与未考虑墙体传湿相比，室内空气相对湿度的降低幅度为，广州：5%左右；西安：3%左右；哈尔滨：3%左右；北京：5%左右。 针对湿热地区白天空调降温、夜间自然通风降温的建筑，研究了墙体湿传递和表面湿迁移在考虑夜间换气的情况下对室内热湿环境及负荷的影响。结果表明，夜间通风换气次数的大小对室温降低效果的差别不明显，而对室内空气相对湿度的影响较为显著；考虑传湿与未考虑传湿时总负荷相比较，夜间换气次数为5次/时，总负荷减少6%左右，15次/时，总负荷却增加20%左右，可见，在热湿气候区，夜间通风换气次数需合理设置才可有效降低空调负荷。 针对我国建筑热湿气候地域差别大的特点，通过对典型气象年最热月和最冷月的平均室外空气相对湿度进行统计，以相对湿度作为区划指标对我国进行湿气候区划分，获得冬季及夏季的湿气侯分区；通过大量分析计算，提出考虑墙体湿传递和表面湿迁移时的建筑负荷的计算方法，获得了湿热、湿冷、干热、干冷地区主要城市在考虑墙体湿传递和表面湿迁移时建筑负荷的修正程度。为工程应用提供参考。
[Abstract]:It is the basis of energy-saving analysis, design and operation control of HVAC system. The cold and hot load of the building is mainly reflected by the heat flow of the inner surface of the enclosing structure, and the heat flow is related to the heat and wet migration of the inside and the surface of the enclosing structure. At present, the relevant design specifications and load analysis software are mostly based on the theory of heat transfer. However, the relationship between the moisture transfer and the surface wet transfer on the load in the enclosure is not well reported. The region of China is vast, the hot and humid climate is various, and the neglect of the wet migration of the enclosing structure will inevitably cause different degrees of error to the indoor thermal environment and the analysis of the cold and heat load of the building. In view of the fact that the existing load calculation method is difficult to embody the influence of the wet migration of the enclosure structure on the building envelope, this paper comprehensively uses the theoretical analysis, the verification analysis, the numerical calculation and the on-site test, and studies the quantitative influence of the wet migration of the enclosing structure on the indoor thermal environment and the cold and hot load of the building. Based on the analysis of the heat and moisture transfer mechanism of the enclosure structure, the mathematical model of the heat and moisture coupling of the enclosure structure and the heat and moisture transfer of the inner surface are established, and the constant value setting of the heat transfer coefficient of the heat transfer in the past is difficult to reflect the change of the coefficient with the environment. In this paper, the function of the transfer coefficient of heat transfer with temperature and humidity is obtained through the study. In order to transfer the nonlinear control equation for the heat and moisture coupling of the envelope structure, the coefficient type partial differential equation module in the COMSOL Multiphysics software is used for programming and solving, and the surface temperature and heat flow in the wall body are considered under various boundary conditions. The heat transfer process is obtained by the differential characteristic of the wall heat transfer. The study found that the reduction of the surface temperature of different materials in the wall of different materials was: the wall of loose wood, the temperature of 0. 1 鈩

本文编号：2429717