Modeling Water Adsorption and Retention of Building Materials From Pore Size Distribution

Water adsorption and capillarity are key phenomena involved during heat and moisture transfer in porous building materials.They account for interaction between solid matrix,liquid water and moist air.They are considered through Water Vapor Adsorption Isotherm(WVAI)and Retention Curve(RC)functions which are constitutive laws characterizing water activity within a porous medium.The objective of this paper is to present a water vapor adsorption and retention models built from multimodal Pore Size Distribution Function(PSDF)and to see how its parameters modify moisture storage for hygroscopic and near saturation ranges.The microstructure of the porous medium is represented statistically by a bundle of tortuous parallel pores through its PSDF.Firstly,the influence of contact angle and temperature on storage properties were investigated.Secondly,a parametric study was performed to see the influence of the PSDF shape on storage properties.Three cases were studied considering the number of modalities,the weight of each modality and the dispersion around mean radius.Finally,as a validation,the proposed model for WVAI were compared to existing model from literature showing a good agreement.This study showed that the proposed models are capable to reproduce various shapes of storage functions.It also highlighted the link between microstructure and adsorption-retention phenomena.

新建建筑外保温围护结构热质耦合传递

为分析新建建筑围护结构的干燥过程,对哈尔滨地区新建建筑围护结构干燥过程的热湿耦合传递进行模拟.考虑液态水的渗透和冬季围护结构内湿分结冰的情况,以液态体积含湿量梯度为质驱动势,以温度梯度为热驱动势,建立不同干燥时段的热质耦合传递质能平衡方程,并对模拟结果进行分析.结果表明:新建建筑围护结构的干燥速率第一年最快,尤其是前几个月;由于围护结构较大的初始含湿量和冬季外侧结冰量,第一年围护结构的保温性能是最差的;在相同的室外气候条件下,与第十年冬季的传热系数相比,第一年要增加约10%,严重影响第一年的建筑能耗.

我国建筑屋面渗漏对策探讨

建筑渗漏是我国建筑屋面的通病，也是我国建筑设计及施工的薄弱环节。从防水材料、防水设计、防水施工、防水管理等方面分析了存在建筑屋面渗漏的原因，并根据我国国情探讨了应采取的对策。

多孔建筑材料液态水传递系数测试方法研究进展

研究多孔建筑材料的湿传递特性对于围护结构的热工性能分析和建筑能耗的预测具有重要意义。多孔建筑材料中湿传递主要分为水蒸气和液态水的传递,在相对湿度较高的建筑环境中液态水的传递占据主导地位。液态水扩散系数、液态水渗透系数、毛细管系数和毛细吸水系数是常用的液态水传递系数。对这4种液态水传递系数之间的理论关联和主要测试方法进行了较为全面的整理,并以毛细吸水系数为例指出了现有研究的不足和未来的发展方向。