围护结构热质耦合传递实验研究

对单层围护结构热质耦合传递过程进行了实验研究。在建立围护结构墙体时,预留一块围护结构用炉渣混凝土砌块测量其孔隙率,初始体积含湿量,干、湿状态的导热系数以及完全干燥状态的密度,并计算砌块固体骨架的导热系数。实验测量321d,该文对实验结果进行了分析,分析结果表明:随着边界条件的变化,围护结构表面及内部温度能够很快达到平衡;但由于湿扩散速度比热传递速度慢得多,因此只有围护结构内外表面的相对湿度受边界条件影响,围护结构中间的相对湿度稳定并持续很高。     

保温层湿工况启动特性分析

在对保温层湿工况启动过程深入分析的基础上,建立了蒸干时间的数值计算模型,模型计算结果和实验测量结果吻合良好.     

空气层对多层墙体热、空气、湿耦合传递性能的影响

为了定量评估附加空气隔层的多层墙体受到压差影响的动态变化和温湿度分布，通过连续驱动势作为边界条件，建立多层墙体各物理场耦合非稳态传递的PDE方程。通过新建模型与COMSOL软件既有物理场接口的对比，验证模型的可行性。与COMSOL软件既有接口相比，新建模型的计算效率与可扩展性得到改善。     

围护结构墙体传热分析及保温层经济厚度的确定

对围护结构墙体传热的理论进行分析,建立其换热微分方程,提出了围护结构墙体保温层经济厚度的计算方法.通过对围护结构墙体实施保温工程后的实例分析与计算,证明其节能效果显著.文中提出的保温层经济厚度计算方法具有较高的精度,对外墙保温结构优化有重要的参考作用.     

建筑墙体热、湿及空气耦合传递

为了研究建筑墙体的热质耦合传递规律，该文考虑了太阳辐射的影响，建立了在第三类边界条件下建筑墙体非稳态热、湿及空气渗透耦合传递的物理及数学模型，开发了相应的数值模拟计算软件。给出了墙体热、湿及空气耦合传递时各部位模拟计算温度随时间的变化曲线及不同使用年限湿容量沿墙体厚度的分布规律，并将墙体的模拟计算结果与现场实测热流及温度进行了对比分析。     

新建建筑围护结构的热质耦合传递对建筑负荷的影响Ⅰ：冬季热负荷

对于节能建筑,围护结构保温性能优劣是影响其能耗的重要标准.以哈尔滨地区为例,通过对新建建筑围护结构热质耦合传递的模拟结果,对比分析了严寒地区典型新建建筑不同设置的多层围护结构在最初四年内热质耦合传递对围护结构墙体热负荷的影响.分析结果表明:围护结构保温层内表面安装隔汽层能有效缓解保温层受潮,对降低能耗较为有利,围护结构外表面粘贴釉面砖时对能耗影响最大,但若降低保温层初始含湿量会降低其影响.     

新建建筑不同设置围护结构的热质耦合传递对建筑负荷的影响Ⅱ:冬季湿负荷

传统建筑室内湿负荷的计算大多不考虑围护结构内表面的散湿量,而围护结构内表面的散湿量尤其是新建节能建筑对室内湿负荷的影响是很大的。以哈尔滨地区为例,分析了严寒地区典型新建建筑不同设置的多层围护结构在最初四年内热质耦合传递对模拟房间湿负荷的影响,并与文献[5]的模拟结果进行对比。分析结果表明：新建建筑围护结构内表面粘贴墙纸或降低围护结构主体砌块的初始含湿量能够降低模拟房间冬季湿负荷;而保温层内侧隔汽层以及围护结构外表面釉面砖的使用都会增加新建建筑的模拟房间冬季湿负荷,但若延后釉面砖的粘贴时间会有所好转。     

可呼吸墙体热质耦合传递研究及数值模拟

可呼吸墙体中不仅有热传递,还伴随着湿传递及空气渗透,并且3个过程互相影响,协同作用。在分析国内外相关资料的基础上,采用热力学方法,并根据多孔介质中多相流体流动描述的体积平均方程,建立了热、湿和空气耦合作用下的可呼吸墙体热质传递模型。推导出热、湿和空气耦合传递等效扩散方程;找到可呼吸墙体热、湿及空气耦合作用下热质传递过程的主要影响因素湿容量Lθ、气压pG和温度T;根据等效扩散方程,通过TDM A算法,可以求得可呼吸墙体内的湿容量分布、气压分布和温度分布,并进行了数值模拟。     

土壤热湿传递下的直埋电缆载流量数值计算

针对土壤热湿过程对直埋电缆载流量的影响,修正土壤热湿耦合模型,联合MAXWELL方程组,建立电磁一热湿三场耦合模型.利用三场耦合模型和COMSOL Multiphysics软件按正交法计算不同敷设土壤类型、干密度和粒径下的YJV220.6/13×6直埋电缆载流量.通过对比正交计算结果的最大、最小载流量组的磁通密度、发热...     

含湿多孔介质内热量迁移的研究

文中分析了未饱和含湿多孔介质内热湿耦合作用过程的热迁移机量,提出了热量迁移数学模型,讨论了不同边界条件对多孔介质内温度分布的影响状况。     

Measuring and modeling vapor boundary layer growth during transient diffusion heat and moisture transfer in cellulose insulation

In this paper, an experimental test facility that permits continuous measurements of transient heat and moisture transfer in porous media is applied to study the vapor boundary layer in cellulose insulation. The experiment measures the relative humidity, temperature and moisture accumulation within the cellulose specimen with a fully developed flow of air at a controlled temperature and humidity provided above the surface. These experimental results are used to verify a mathematical model, which is used to develop an expression for moisture diffusivity (α_m) that is analogous to thermal diffusivity, and takes into consideration moisture storage. The moisture diffusivity is used to calculate the vapor density in the boundary layer and the size of vapor boundary layer in cellulose insulation. It is found that the moisture storage effect has a very significant effect on the vapor boundary layer and cannot be ignored. For cellulose insulation, the size of the vapor boundary layer may be over predicted by a factor of ten when moisture storage is neglected.     

Study of heat and moisture transfer in soil with a dry surface layer

Mathematical model for describing simultaneous heat and moisture transfer in the porous soil with a dry surface layer was developed by using the volume-averaging method. Numerical simulation was conducted to investigate water evaporation, transient distributions of temperature and moisture in the porous soil at environmental conditions, which might be useful for agricultural application. In order to validate the mathematical model and numerical method, an experiment was conducted under natural environmental conditions. An additional experiment was conducted in a closed-loop wind tunnel to investigate the temperature effect on soil moisture transport. Theoretical and experimental results indicate that the dry surface layer has an important effect on heat and moisture migration in soil and the influence of temperature on moisture transport in unsaturated soil is significant.     

Non-Fourier effect in the presence of coupled heat and moisture transfer

The objective of this paper is to study heat and mass transfer coupling under non-Fourier effect. The non-Fourier model is applied on Luikov’s equations. The governed equation is called Luikov’s Corrected (LC) equations and is solved by hybrid analytical–numerical method. Heat and mass propagation in LC field is shown to be wavelike; so, wavefront speed is obtained. Applying non-Fourier model instead of Fourier’s law sensitizes Luikov’s equations to respond in fast transient process. Further, the effect of heat and mass transfer coupling on interpreting non-Fourier affects is investigated. It is seen that the presence of heat and mass transfer coupling reduces wavefront speed with respect to uncoupled non-Fourier heat transfer.     

太阳热水器保温层发泡技术探讨

太阳热水器水箱的聚氨酯保温层的质量至关重要。如果没有性能优异的保温材料,集热管的吸热效率再高,又有多大意义?聚氨酯产品历来有“三分产品,七分发泡”的说法。也就是说,不仅需要质量好的聚氨酯发泡料,更需要一个科学的发泡工艺和严格的操作规程,这样才能生产出合格的聚氨酯泡沫,但实际上发泡的问题比比皆是,出现许多太阳热水器行业特有的质量问题,导致聚氨酯泡沫质量大打折扣。泡沫收缩是发泡工艺中普遍存在的问题,它导致水箱变形、起鼓、起楞甚至开裂。本文通过泡沫收缩成因的分析,来探讨提高太阳热水器发泡质量途径。一泡沫收缩成因分…     

Modeling heat and moisture transfer through fibrous insulation with phase change and mobile condensates

This paper reports on a transient model of coupled heat and moisture transfer through fibrous insulation, which for the first time takes into account of evaporation and mobile condensates. The model successfully explained the experimental observations of Farnworth [Tex. Res. J. 56 (1986) 653], and the numerical results of the model were found to be in good agreement with the experimental results of a drying test. Based on this model, numerical simulation was carried out to better understand the effect of various material and environmental parameters on the heat and moisture transfer. It was found that the initial water content and thickness of the fibrous insulation together with the environmental temperature are the three most important factors influencing the heat flux.     

室内空调条件下孝感市建筑物屋顶、墙体的隔热节能指标的选取

根据建筑物热工气候分区,对夏热冬冷地区的孝感市运用“建筑热环境与建筑节能设计标准相关控制法”中所提出的简化公式及孝感市的气象参数,计算出了室内空调条件下建筑物屋顶、墙体的隔热控制和节能控制指标,为我国夏热冬冷地区及其他地区建筑的隔热和节能控制设计提供参考依据。     

定壁温条件下竖直管内沸腾传热特性研究

文章建立了应用于蒸发器的满液式竖直管三维物理模型,并采用多相流混合模型对满液式竖直管内的沸腾传热特性进行数值模拟。而后根据模拟结果得到管内静压、管壁加热温度和管长对满液式竖直管内流体的温度、含气率以及该竖直管沸腾传热系数的影响规律,并分析管壁加热温度、管长、管内静压和蒸发温度对满液式竖直管内沸腾传热特性的影响。分析结果表明:满液式竖直管的长度越长,蒸发器的总换热量越大;当满液式竖直管的壁面温度由376 K升高至388 K时,若该竖直管的长度为1.6 m,则其沸腾传热系数提高了7.4%,若该竖直管的长度为1.2,1.0 m,则其沸腾传热系数均升高了约3.3%;在蒸发器竖直管沸腾传热过程中,其换热量和壁面温度呈正相关;当蒸发温度较低时,满液式竖直管内的静压对管内流体的含气率以及该竖直管的沸腾传热系数影响较大。     

An analytical method to calculate the coupled heat and moisture transfer in building materials

A dynamic model for evaluating the transient thermal and moisture transfer behavior in porous building materials was presented. Both heat and moisture transfer were simultaneously considered and their interactions were modeled. An analytical method has been proposed to calculate the coupled heat and moisture transfer process in building materials. The coupled system was first subjected to Laplace transformation, and then the equations were solved by introducing the Transfer Function Method. The transient temperature and moisture content distribution across the material can thus be easily obtained form the solutions. The results were compared with the experimental data and other analytical solutions available in the literature; a good agreement was obtained.     

Network numerical simulation of coupled heat and moisture transfer in capillary porous media

In this paper we present the numerical solution of the problem of coupled heat and moisture transfer in porous materials. A network model introducing an analogy based in the equivalence mass transfer-electrical current is proposed to obtain the numerical solutions. An algorithm based on a finite-difference scheme for the spatial variable (as in the lines method because the time remains as a continuous variable) is formally equivalent to those derived from the mathematical model. An implementation of the Network Simulation Method is used to derive a solution to the heat and mass conservation coupled equations in porous media for the cases of distributed and lumped models. The obtained values by the theoretical model are compared with other author data to demonstrate the efficiency of the method used, moreover all the cases the convergence is always quickly reached.