Effects of combined heat and mass transfer on heating load in building drying period

In initial used building with EPS walls, the wall still contains a considerable amount of water that evaporates over time. In order to analyze the effect of moisture levels on a drying building energy performance, the heat and moisture coupling transfer of building wall with multilayer composition in the cold serious area Harbin, China, was simulated. The freezing of liquid moisture in exterior envelope was considered and the moisture content gradient was used as mass transfer driving forces. The effect of some impact factors, as initial moisture content, vapor retarder, interior wallpaper and exterior glazed brick on the wall energy consumption were also analyzed. It is concluded that the effect of drying are most significant during the first year of building initial use. The drying rate of the new building was significantly high in the first year, especially in the first few months. These changes during initial drying often account for a significant fraction of the overall load and have notable effect on the building energy performance.     

湿传递对建筑墙体传热性能的影响

建筑物的耗能与建筑围护结构的传热传湿密切相关,了解建筑墙体内部的热湿传递对建筑节能有重要影响。以相对湿度和温度梯度为驱动势建立墙体一维非稳态热、湿和空气耦合传递模型(HAM模型),并利用有限元法进行了数值求解,重点关注了湿传递对传热的影响。数值结果表明:考虑传湿时墙体内部温度波动小,墙体进行热湿传递会产生湿积累,降低墙体使用年限;考虑传湿时通过墙体总传热量比不考虑传湿时多7.5%;考虑传湿时内壁面最大平均数比不考虑传湿时大0.78。     

新建建筑围护结构热质传递对室内温湿度环境的影响

新建建筑第1年由于较大的内表面散湿量会影响室内的温湿度水平,严重的会引起围护结构内表面霉菌。为分析新建建筑第1年围护结构的湿传递对室内温湿度环境的影响,本文对哈尔滨地区新建建筑综合热质耦合传递进行了模拟,分别建立了围护结构和室内空气的质能平衡方程,并讨论了夏季不同的室内通风率对围护结构内表面散湿量及室内温湿度的影响,得出了几点重要结论。     

新建建筑围护结构干燥过程的热质耦合传递研究

本文模拟了新建建筑围护结构干燥过程中的热质耦合传递过程。对比了室内条件、围护结构保温层热侧的隔汽层、冷侧的空气层以及围护结构内表面墙纸的使用对新建建筑围护结构干燥过程中热质耦合传递的影响,并得出几点重要结论。     

围护结构热湿耦合传递模型及简便求解方法

为了预测围护结构内的温度和湿度分布,以连续变量,相对湿度和温度为驱动势,考虑热传递与湿传递之间的耦合作用,建立了围护结构热湿耦合传递非稳态模型,并提出了基于多物理场耦合仿真模拟软件COMSOL的热湿耦合传递模型简便求解方法。通过对比新建模型模拟结果与HAMSTAD标准验证实例,验证了模型及求解方法的准确性。     

软岩类材料冻融过程水热迁移的实验研究初探

进行软岩类材料-水泥砂浆的冻融水热迁移实验，对两种不同类型的软岩类材料进行开放系统下具有温度梯度的水热迁移实验研究。实验结果表明：不同类型的软岩类材料水热迁移程度不同，试样中的石英矿物含量越高，温度场重新分布时间越长；温度梯度是水分迁移的主要驱动力，当温度梯度越大时，水分场越快达到重新分布状态；孔隙率越高，冻结过程越长。     

极端热湿地区围护结构热湿耦合传递模型

极端热湿地区常年高温多雨,为了准确预测围护结构内的温度和湿度分布,模拟高温、高湿和高太阳辐射对围护结构的影响,建立了适用于极端热湿地区的围护结构热湿耦合传递模型,在边界条件中加入太阳辐射和雨水负荷对传热传湿的影响,考虑了随材料含湿量不断变化的材料物性参数。为了求解模型,提出了基于计算机软件COMSOL的模型求解方法,利用MATLAB计算方程组不断变化的系数,并确定了软件容差和网格的设置条件:相对容差推荐设定在0.001,绝对容差设定为0.000 1,网格按极细化划分。通过对比HAMSTAD标准实例验证了模型的准确性。     

新建节能建筑墙体材料层及排布对干燥过程的影响

建筑围护结构内的热湿耦合传递是一个非常复杂的过程,其研究是降低建筑能耗、评估和预防湿害、提高室内热舒适性、室内卫生及优化围护结构性能的基础。新建节能建筑墙体具有初始含湿量大的特点,若墙体湿积累过大,则容易出现墙体表面剥蚀、渗漏、发霉甚至结构出现损坏的现象。墙体干燥时,传热传质过程同时发生且相互耦合。目前相关热物性仿真软件、理论研究和设计规范主要建立在热传递的基础上,忽略了湿传递的影响,对新建建筑墙体干燥不适用。WUFI~? Pro热湿仿真软件充分考虑了材料本身含湿量、风驱雨、太阳辐射、长波辐射、毛细传输和夏季结露等典型气候的影响,实现了对自然气候条件下建筑构件非稳态热湿性能的真实计算。节能墙体多在外墙添加内外保温层来增加围护结构的传热热阻,且在保温层内外两侧分别添加隔汽层和空气层的措施来防止保温层受潮,最终提高围护结构的保温性能。为墙体美观,多在围护结构的内外两侧分别黏贴墙纸和釉面砖。采用WUFI~? Pro对北京地区2种典型的建筑墙体进行热湿耦合传递模拟,分析新建建筑墙体在不同保温层材料和位置时的干燥过程,以及保温层两侧的隔汽层和空气层、墙体两侧的墙纸和釉面砖对墙体干燥过程的影响。模拟用室外条件为北京典型气象年小时室外气象参数,室内条件设定室内冬季供暖温度T_1=20℃,夏季室内温度设计值T_2=25℃,全年平均相对湿度为50%。模拟外围护结构属于西向,墙体温湿度初始条件为:相对湿度为100%,温度为15℃。模拟结果表明:内保温层的设置非常不利于围护结构的干燥,容易在内保温层和砌块之形成湿积累,降低围护结构的耐久性;EPS、PU和XPS都能降低围护结构含湿量,但EPS更有利于墙体干燥;隔汽层和空气层的添加可一定程度上阻止保温层受潮,避免造成湿积累,进而提高围护结构的保温性能;釉面砖和墙纸的黏贴将严重延缓围护结构的干燥过程,降低围护结构的保温性能,缩减建筑构件的使用寿命。     

Experimental and theoretical investigation of non-isothermal transfer in hygroscopic building materials

In this paper a modified two-dimensional Luikov model for evaluating the non-isothermal moisture migration in porous building materials was proposed. The coupled heat and moisture transfer problem was modeled. Vapor content and temperature were chosen as the principal driving potentials. The coupled equations were solved by a numerical method, which consists of a finite difference technique with a fully implicit scheme in time. Two validation experiments were developed in this study. The evolution of transient moisture distributions in both one-dimensional and two-dimensional cases was measured. A comparison between experimental results and those obtained by the numerical model proves that they are fully consistent with each other. The modified model can be integrated into a whole building heat, air and moisture transfer model.     

多孔墙体湿分传递与室内热湿环境研究

简要回顾了多孔建筑材料基本湿特性和湿迁移基本理论。对多孔墙体湿迁移的水蒸气理论模型、有效渗透深度理论模型、蒸发与凝结理论模型、考虑液体和水蒸气同时传递的热湿耦合模型和室内热湿环境平衡方程进行了综合分析。指出目前多孔建筑材料热湿传递和室内热湿环境研究的热点和存在的问题。     

多层墙体热湿耦合传递模型及验证

从非平衡热力学角度论证了多层墙体热湿耦合过程采用水蒸气分压力和温度作为驱动势的合理性。由于水蒸气分压力是含湿量和温度的函数,利用全微分思想,建立了多层墙体热湿耦合传递模型,该方法可避免Budaiwi方法在热湿耦合模型建立过程中采用的空气含湿量与相对湿度间的近似表达式,而且简化了方程系数,便于方程的求解。通过对多层墙体求解结果的对比,验证了该模型的有效性。     

多孔围护结构热湿耦合传递过程研究及进展

相对于干热干冷气候区,湿热湿冷气候区的多孔围护结构热湿耦合作用引起的传热计算是一个复杂的过程,在建筑节能工程计算中依然采用的是经验方法.本文以多孔围护结构热湿耦合传递过程为研究对象,对业界在理论研究、计算方法及模拟工具等方面取得的进展进行了深入的研究分析,总结了国内外在多孔围护结构热湿耦合传递过程研究中所取得的主要成果.针对存在的问题,指出了其应用的局限性,同时展望了该领域的发展趋势.     

两种常见墙体的热湿迁移特性分析

大多数建筑墙体均为多孔介质材料,多孔介质墙体中湿迁移与热迁移是互相耦合的过程,湿迁移对热迁移有着重要的作用,例如会使热导率明显增加,同时,热过程对湿过程也有着影响作用。基于Fourier定律、Fick定律、Darcy定律,以温度和空气含湿量为驱动势建立了多层多孔介质墙体热湿耦合迁移数学模型,对两种常见墙体（红砖墙体和加气混凝土墙体）进行计算分析。结果表明,加气混凝土墙体比红砖墙体具有更好的保温隔热性能,但更容易发生湿积累和引发湿破坏。     

地下洞室多孔墙体热湿传递的数值模拟

提出了一种以温度与相对湿度为驱动势的多孔墙体热湿耦合传递的数学模型,该模型同时考虑了水蒸气与毛细孔内液态水的传递。采用控制容积法将理论方程组离散并编制了计算程序,对深埋地下洞室的墙体进行了热湿传递的数值模拟,得到了墙体温度、相对湿度、热流率、湿流率的变化规律。结果表明,墙体传热过程趋于稳定的时间远小于传湿过程。     

地埋管周围土壤冻结传热特性的实验研究

本文通过搭建沙箱实验平台模拟地埋管低温取热过程,采用控制变量法研究含水率和管内流体温度对地埋管周围土壤冻结传热的影响,并对实验结果进行分析和数值拟合。实验结果表明:随着含水率的增加或管内流体温度降低,土壤冻结区厚度增加,冻结区土壤温度降低,传热速率加快,而且管内流体温度降低对土壤冻结的影响更大,管内流体温度对冻结边界层和土壤温度的影响比含水率分别大32.57%和11.62%。     

Simulation of coupled heat and moisture transfer in air-conditioned buildings

The simultaneous heat and moisture transfer in the building envelope has an important influence on the indoor environment and the overall performance of buildings. In this paper, a model for predicting whole building heat and moisture transfer was presented. Both heat and moisture transfer in the building envelope and indoor air were simultaneously considered; their interactions were modeled. The coupled model takes into account most of the main hygrothermal effects in buildings. The coupled system model was implemented in MATLAB-Simulink, and validated by using a series of published testing tools. The new program was applied to investigate the moisture transfer effect on indoor air humidity and building energy consumption under different climates. The results show that the use of more detailed simulation routines can result in improvements to the building's design for energy optimisation through the choice of proper hygroscopic materials, which would not be indicated by simpler calculation techniques.     

空气间层对聚苯复合外保温墙热湿耦合传递的影响

聚苯(EPS)复合外保温墙中的空气间层对其热湿耦合传递有着重要的影响.针对不同空气间层厚度的EPS复合外保温多孔砖墙,在以上海为代表的夏热冬冷地区的气候条件下,利用已有的热湿耦合传递数学模型和计算软件CHAMPS-BES,进行热湿耦合传递数值模拟.结果表明:空气间层越厚,多孔砖层的初始水分向空气间层扩散、迁移越快;空气间层越厚,空气间层和EPS板的峰值含湿量越高,达到湿稳定所需时间越长.当空气间层厚度为20mm时,水分对EPS复合外保温多孔砖墙传热系数总的影响最显著,高达34%.tif板施工时,在保证其黏结强度的前提下,宜适当减小空气间层的厚度.     

离心玻璃棉热湿传递特性实验研究

离心玻璃棉具有良好的保温隔热性能,被广泛用于建筑保温技术。为了研究夏热冬冷地区用于墙体内保温的离心玻璃棉热湿传递特性,设计了一套实验装置,通过实验测试了特定温湿度条件下离心玻璃棉的水蒸气渗透性能,研究了温度对离心玻璃棉湿传递过程的影响,并验证了一维稳态传热传质模型对离心玻璃棉保温材料的适用性。实验结果表明,离心玻璃棉内部所传递的湿流密度随着水蒸气分压力差的增加而增大;其水蒸气渗透系数值受水蒸气分压力差的影响较小;而且在特定的温湿度范围内,温度对离心玻璃棉的湿传递过程几乎没有影响。     

住宅建筑围护结构内外表面热阻对传热系数的影响

冬季通过建筑围护结构传递的热量由3个因素决定:壁体内表面换热阻、壁体外表面换热阻及壁体材料层的导热系数。这3个因素受室内外热冷源、风速及材料层的含湿量影响。通过对一使用10年左右住宅建筑的现场测试与理论计算对比得出:在进行冬季围护结构热工计算时,应对以上3个参数根据不同实际情况作相应的修正。     

Hygrothermische Wirkungen von Raum‐ und Außenoberflächen

The hygrothermal effect of inside and outside building envelope surfaces. In the past the protection of building constructions under outdoor and indoor climate conditions was one of the most important subjects building physics. Nowadays the energy balance and the hygrothermal performance of building envelopes are current topics. This paper deals with the coupled heat and moisture transfer on the internal and external envelope surfaces. By means of numerical simulation and laboratory investigation the influence of the internal surface of exterior walls on the indoor air humidity is demonstrated. The influence of evaporation cooling on the energy transfer in winter time and during the warm season requires investigations on dewing and driving. It depends on the hygroscopic parameters of the outside wall coating. The effect of infrared reflecting coating is determined. It is shown in which way heat sources integrated in exterior walls could be a possibility to avoid microbiological growth on building envelopes.