多孔建筑材料湿物理性质的测试方法研究

发布时间：2018-04-20 16:18

本文选题：多孔建筑材料 + 湿物理性质　；参考：《华南理工大学》2014年博士论文

【摘要】：多孔建筑材料的湿物理性质是分析建筑围护结构热湿传递过程的重要参数。用准确可靠的方法测试多孔建筑材料的湿物理性质对围护结构的热工设计、室内热湿环境的分析及建筑能耗的计算有着重要意义。本文以加气混凝土（国产及比利时产）、硅钙板和瓷砖等典型多孔建筑材料为测试材料，首先研究了测试试件的最佳称重方法和干燥方法。通过理论和实验分析，发现对大尺寸的试件可以进行直接称重，而小尺寸的试件在称重过程中应用非吸湿容器密封。对大多数材料推荐采用70°C烘干法进行干燥。其次，本文参考多项国际和地区标准，在各种条件下进行了平衡吸放湿实验、蒸汽渗透实验、毛细吸水实验、真空饱和实验以及压力平板实验，测试了上述材料的等温吸放湿曲线、蒸汽渗透系数、吸水系数、毛细饱和含湿量、液态水扩散系数、表观密度、孔隙率、真空饱和含湿量和保水曲线等各种物理性质。研究发现，上述实验的重复性都较好，测试结果的重复性误差一般不大于材料不均一性引起的误差。等温吸湿曲线、蒸汽渗透系数、毛细饱和含湿量、表观密度、孔隙率和真空饱和含湿量对温度的变化不敏感，在10-40°C范围内温度变化造成的影响一般不大于实验的重复性误差。吸水系数和液态水扩散系数随温度的升高而变大，，其关系可根据Lucas-Washburn公式预测。此外，本文进一步对测试过程中的各种潜在影响因素（如试件尺寸、中间步骤、预处理方法、测试时长、实验压力等）进行了系统研究，发现大多数因素对实验结果没有明显影响。本文还改进了蒸汽渗透实验、毛细吸水实验和压力平板实验的装置，对平衡吸放湿实验和蒸汽渗透实验的结果提出了新的表达方法，并证明了对毛细吸水实验第一阶段的数据进行分析时只需要进行普通的线性拟合。最后，本文以一维稳态蒸汽渗透过程为例，分析了物性参数的误差对传湿计算的影响。结果表明，蒸汽渗透系数的常物性取值会对蒸汽传递过程的计算带来明显误差。蒸汽渗透系数的误差对蒸汽传递速率的影响程度恒定，而含湿量或相对湿度的误差对蒸汽传递速率的影响程度与当前含湿量或相对湿度有关。
[Abstract]:The wet physical property of porous building materials is an important parameter to analyze the heat and moisture transfer process of building enclosure. It is of great significance to test the physical properties of porous building materials by accurate and reliable method for thermal design, analysis of indoor thermal and wet environment and calculation of building energy consumption. In this paper, typical porous building materials such as aerated concrete (made in China and Belgium), calcium silicate plate and ceramic tile are used as test materials. First, the optimum weighing method and drying method of test specimens are studied. Through theoretical and experimental analysis, it is found that large size specimens can be weighed directly, while small size specimens can be sealed by non-absorbent containers in the weighing process. 70 掳C drying is recommended for most materials. Secondly, the experiments of equilibrium moisture absorption and desorption, vapor permeation, capillary water absorption, vacuum saturation and pressure plate experiments have been carried out under various conditions with reference to many international and regional standards. The isothermal moisture absorption and desorption curves, vapor permeability coefficient, water absorption coefficient, capillary saturated moisture content, liquid water diffusion coefficient, apparent density, porosity, vacuum saturated moisture content and water retention curve were measured. It is found that the repeatability of the above experiments is good, and the repeatability error of the test results is not generally greater than that caused by the heterogeneity of materials. The isothermal moisture absorption curve, vapor permeability coefficient, capillary saturated moisture content, apparent density, porosity and vacuum saturated moisture content are not sensitive to the temperature change, and the effect of temperature change in the range of 10-40 掳C is generally less than the repeatability error of the experiment. The water absorption coefficient and the diffusion coefficient of liquid water increase with the increase of temperature, which can be predicted by Lucas-Washburn formula. In addition, various potential influencing factors (such as specimen size, intermediate steps, pretreatment methods, test duration, experimental pressure, etc.) in the process of testing are systematically studied in this paper. It was found that most of the factors had no significant effect on the experimental results. This paper also improves the apparatus of vapor permeation experiment, capillary water absorption experiment and pressure plate experiment, and puts forward a new expression method for the results of equilibrium moisture absorption and desorption experiment and steam permeation experiment. It is proved that only a general linear fitting is needed to analyze the data of the first stage of capillary water absorption experiment. Finally, the effect of the error of physical parameters on the calculation of moisture transfer is analyzed by taking the one-dimensional steady state vapor permeation process as an example. The results show that the constant physical properties of the vapor permeability coefficient will bring obvious error to the calculation of the steam transfer process. The influence of the error of vapor permeability coefficient on the steam transfer rate is constant, while the influence of moisture content or relative humidity error on the steam transfer rate is related to the current moisture content or relative humidity.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU502

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