Non-contact methods of measuring moisture concentration in external layers of building partitions: III—Water vapour condensation on the cementitious surfaces

This paper presents the results of the larger study into a potential application of laser radiation for the detection of phase transition processes in low temperatures occurring on the surface layers of cementitious materials. An attempt was made to identify relationships between the environmental conditions—temperature and air humidity, and the selected parameters of the reflected light. Onset of the condensation process and formation of water microdrops on the surface of the material leads to the phase displacement of individual laser rays, which are represented by different speckle images.

Although the analysis of parameters of the reflected light are very difficult in the case of porous materials because of highly developed roughness of the surface structure it has been proved that a dynamic study of the phase transition phenomena can be successfully carried out without mechanical intervention.     

Non-contact methods of measuring moisture concentration in external layers of building partitions. I—The influence of geometrical microstructure on the kinetics of moisture condensation on glass surfaces

This paper presents the results of the larger study on the potential application of laser radiation for the detection of phase transition processes. The proposed experimental method allows a dynamic study of the phenomena without mechanical intervention. This seems to be the best practical solution particularly when the access for the other methods is very restricted. The investigations give an evidence of the strong relationships between the rapid growth of water vapour condensate and the roughness of the surface. Condensation process therefore can be modified by a careful design of the geometrical structure of surface.     

Water movement in porous building materials—V. Absorption and shedding of rain by building surfaces

We discuss in terms of unsaturated flow theory the absorption and shedding of rain falling on porous surfaces, and present a finite element solution of the one-dimensional nonlinear diffusion equation subject to a constant flux boundary condition. This shows how the water absorption depends on the rainfall rate and on the hydraulic diffusivity of the absorbing material. For a class of hydraulically similar porous building materials we establish the dependence of absorption on sorptivity and porosity, and give a general expression for the time to surface saturation. We briefly consider also the fluid mechanics of rainwater run-off.     

The effect of geometrical microstructure of solid surfaces on the kinetics of water vapour condensation process

Alternating environmental conditions not only influence the long-term performance of construction materials but also the overall energy consumption. Humidity in building partitions has particularly strong effect. Condensation of water vapour and subsequent absorption of water adversely affect thermal properties and, if persistent may lead to the severe deterioration of building envelop.This paper presents the results of a non-contact dynamic study of the condensation process. The investigations give a clear evidence of the strong relationships between the rapid growth of water vapour condensate and the roughness of the surface. Experimental results confirmed that the kinetics of condensation process depends very much on the geometrical characteristics of surfaces—their roughness. It is proposed by the authors to adopt for analysis of the process two parameters—mean arithmetic deviation of profile R_a and mean spacing of profile S_m. Critical value of free Gibbs enthalpy, critical radius of nucleus on surfaces of complex microstructure as well as rate of condensate growth during the second stage of condensation process have been expressed as functions of R_a and S_m.     

北方地区房屋围护结构内表面结露发霉现象的原因及解决方法

本文结合具体工程论述了北方地区采暖房屋围护结构内表面出现结露发霉现象的原因及解决方法 ,可为房屋设计与施工提供参考和依据。     

Water movement in porous building materials—VIII. Effects of evaporative drying on height of capillary rise equilibrium in walls

A theoretical analysis of the effect of the continuous loss of water by evaporation on the rising damp equilibrium in masonry walls is presented in this paper. The analysis predicts heights of capillary rise in agreement with those observed in practice in walls which lack an effective damp proof course.     

夏热冬冷地区居住建筑节能评估中的检测方法探讨

对我国夏热冬冷地区居住建筑节能评估中需在实验室及现场分别测试的各种热工性能参数、所用的仪器设备及相关检测方法进行了探讨。     

严寒地区外贴聚苯板复合墙体传湿研究

目前,我国节能建筑广泛采用外贴聚苯板复合墙体,由于这种外保温墙体热湿传递的合理性一般均不设置隔气层。在严寒地区冬季,水蒸气容易在聚苯板内发生凝结,质量湿度增量可能超过限值。文中对室内空气温度、室内空气相对湿度、墙体主体结构材料与厚度、外饰面蒸汽渗透阻、保温材料厚度、室外气候条件等影响聚苯板质量湿度增量的因素进行了定量的分析,给出了外贴聚苯板复合墙体用于严寒地区的具体限制条件。     

Effects of inorganic metal toxicity on bod—I methods for the estimation of bod parameters—II

Metal toxicity: In this study, the effects of HgCl₂, HgSO₄, K₂Cr₂O₇, CuSO₄, ZnSO₄ and Al₂(SO₄)₃ on BOD were investigated using a respirometer. When these inorganic metal compounds were added to a synthetic medium, respirometric BOD values and bacterial growth in an aeration system were affected. Parameter estimation: Some new solutions of the first order equation are time saving alternatives to the existing ones. Ultimate BOD values obtained from the second order equation are significantly higher than those produced from the first order equation. There is linear relationship between first and second order BOD parameters using crude sewage samples, but not when synthetic medium is used.     

Thermal modelling of an industrial building with solar reflective coatings on external surfaces: case studies in China and Australia

Most industrial buildings rely almost entirely on air-conditioning systems to provide thermal comfort to staff and customers who use the premises. As an alternative to this active approach, passive strategy is recommended to either fulfil this task or to help reduce energy consumption of air-conditioning systems already installed. Applying solar reflective coatings on external surfaces of the building, a key passive strategy, appears to offer an effective solution to reduce solar heat, especially during the summer, penetrating through the building fabric. This article discusses a study that uses computer thermal modelling to investigate the effectiveness of this strategy and to explore its contribution to operational energy savings. Detailed mathematical modelling in accordance with thermodynamic and heat transfer theories through the building fabric is illustrated and solutions to the mathematical problems are presented. The study consists of a comparison between two scenarios (normal coating and reflective coating) in three locations in China and one in Australia. The application of solar reflective coatings on external surfaces of the building produces energy savings for all the four locations and is found to be more beneficial in hot climates where there is a considerable need to reduce summer solar gains.     

解析外墙外保温技术在建筑设计中的运用

介绍了外墙外保温技术的应用原理及设计优势,主要对外挂式外保温、聚苯板与墙体一次成型、聚苯颗粒保温料浆等外墙外保温技术的运用方式进行了详细论述,并分析了其在节能方面的意义,指出外墙外保温技术具有良好的经济及环保效益。     

建筑无机保温砂浆在外墙外保温工程中的应用

对建筑无机保温砂浆材料的性能、施工特点和成本优势进行了介绍,分析了影响无机保温工程施工质量的因素,并通过采取一系列的施工措施来加强对无机保温工程施工质量的控制,以达到建筑节能的效果。     

多层建筑消火栓给水系统形式的探讨

根据室内消火栓给水系统的构成,并结合GB 50016-2006建筑设计防火规范对给水系统进行了分析,明确了多层建筑消火栓给水系统的三种形式和适用范围,可供多层建筑消防水设计参考。     

论外墙保温技术在建筑节能中的应用研究

就目前我们国内比较常用的外墙保温技术及节能材料进行了对比,并详细论述了常见的墙体外保温技术的种类,以促进外墙保温技术的发展,从而推进建筑节能的发展。     

高层建筑消防水系统腐蚀治理问题的研究

杂质沉淀、微生物及溶解氧的侵害是影响消防水系统的主要原因。管道腐蚀易导致管道泄漏;腐蚀产物会减小管道有效截面,降低水流量和水压,甚至堵塞喷头。建议深入进行管道腐蚀机理方面的研究,加强交流,探索腐蚀防治的方法;针对消防水系统腐蚀建立相应规范,推动相关研究的发展;消防水系统的水质宜采用化学控制,减少氧气补充量。建议安装完成后对新消防水系统进行化学清洗;清除旧消防水系统沉淀物及腐蚀产物,并进行化学镀膜处理;定时检测水质及管道腐蚀情况。     

浅析建筑物内供水系统电机的控制方式

根据多年工程实践经验，从简单实用、维护方便、降低工程造价等几个角度，通过对几种水泵控制方式和供水系统组成方式进行分析，推荐了两种建筑物中实用的供水控制方式。     

多层建筑室内消防给水系统设置探讨

对多层建筑中建立以自动喷水灭火系统为主体的室内消防给水灭火系统的必要性和可行性 ,以及“简易自动喷水灭火系统”在多层建筑中应用的可能性和合理化进行探讨 ,并提出几种易推广、普及的“简铁自动喷水灭火系统”方案     

A numerical simulation method for analyzing the thermal improvement effect of super-hydrophilic photocatalyst-coated building surfaces with water film on the urban/built environment

As an application of the super-hydrophilicity of a photocatalyst (TiO₂) coating, buildings are cooled by sprinkling water on their external surfaces coated with TiO₂. This is a new cooling technology that was recently developed in Japan. In order to make better use of this cooling system, quantitative prediction and evaluation of the cooling effect on the urban/built environment is required during design. In an attempt to provide a computer-aided simulation tool for supporting the above-mentioned design, we introduce a thermal simulation tool that was developed previously by the authors’ group. The goal of the present study is to develop a numerical model by which to predict the temperature of a TiO₂-coated surface with a water film and integrate the calculation algorithm into the simulation tool. The availability of the proposed model was discussed in the present paper. Various urban districts in downtown Tokyo were selected for a discussion of the availability of the simulation tool in which the proposed model is integrated. Simulations were performed to quantify the thermal improvement effect of the cooling system in terms of surface temperature reduction, mean radiative temperature (MRT), heat island potential (HIP), indoor air temperature, and cooling load reduction.     

A study on a porous residential building model in hot and humid regions: Part 1—the natural ventilation performance and the cooling load reduction effect of the building model

This study targets environmental load reduction in hot and humid regions. It reveals the effects that porous residential buildings have on the natural ventilation performance and, consequently, the cooling load reduction. Two residential building models, namely a model with a void ratio of 0% and a model with a void ratio of 50%, are evaluated using computational fluid dynamics (CFD) analysis and thermal and airflow network analysis. The analysis on components of the heat load indicates that improvements in the natural ventilation performance would significantly reduce the cooling load.