颗粒物对围护结构的穿透系数与换气次数关系的探讨

室外颗粒污染物可以通过建筑围护结构缝隙进入室内,并对室内空气品质产生影响。通常用穿透系数来表征室外颗粒污染物穿过建筑围护结构进入室内的通过性。考虑到建筑围护结构在室内外空气交换流通和室外颗粒物进入室内的过程中所起到的关键作用,建立了室外颗粒物对围护结构的穿透系数与换气次数的关联性模型。分析、阐述了换气次数对颗粒物穿透系数的影响。通过模拟工况的数值计算,讨论了在研究室外环境对室内颗粒污染物浓度的影响中考虑穿透系数与换气次数之间关联性的必要性。     

细致木板建材VOC释放实验研究

随着大量的小区住宅建筑建设和各种装饰材料的使用,室内的有毒气体成为影响居民健康的污染气体。针对目前室内重要污染物即挥发性有机化合物(VOC),在实验室中构建模拟住宅环境,通过改变温度和换气次数对干材料中的VOC释放情况作了分析。实验结果表明:相对环境温度的升高,加剧了分子运动,促进室内材料VOC快速释放;高频率换气次数能够加快VOC扩散。实验结果为改善室内环境提供一定参考和借鉴。     

温度变化对板材内VOC散发特性影响的研究

扩散系数及分配系数受温度的影响,为系统地研究温度对VOC散发的影响,本文建立了基于传热传质理论下板材内VOC散发的连续模型,并用该模型对常用板材中VOC的散发进行分析.模拟结果同计算的理论值以及实验数据均能较好的吻合.当温度从18℃升高到50℃时,不论是初始时刻的VOC散发速率还是散发稳定时刻的浓度值,都有明显的升高,散发24小时后,板材在50℃下的散发量约为30℃下散发量的2.5倍;同时本文对环境温度tf波动情况下的VOC散发结果模拟表明:空气中污染物在材料表面表现出沉降与二次挥发的现象.对密闭小室中板材内部VOC分布的模拟结果表明,随着散发时间的推移,材料内部的污染物浓度将逐渐趋于均匀.     

住宅换气次数与污染物浓度的研究

本文于2017年1月对西安市一所装修完成半年的住宅建筑进行室内温湿度、换气次数、污染物浓度测试,分析不同的窗户开启面积比例下换气次数与污染物浓度的关系。结果表明,开窗通风可以有效降低室内气态污染浓度。建筑密闭超过12h后就应进行一定时间的通风。保证窗户不低于10%的开窗比例对排除卧室污染物有积极作用。     

换气次数对板式家具甲醛散发影响的研究

为了研究换气次数对板式家具甲醛散发的影响,对天津某住宅客厅先进行为期40d的甲醛浓度现场测试,并在相同工况下,利用PHOENICS软件进行模拟值和测试值对比验证,最后,运用该软件模拟不同换气次数对板式家具甲醛浓度分布规律影响,得出随着换气次数增大,室内甲醛浓度逐渐减小的结论。     

某住宅室内装修污染物分析与控制

对当前室内装修所用到的装修材料进行了介绍,分析了室内装修材料带来的室内污染物和对人体的危害。以一套经过新装修的住宅为例,主要对卧室内的污染物种类与含量进行了测量,给出室内污染物浓度随着时间的变化情况,测量发现室内主要污染物甲醛的浓度受温度、相对湿度、天气状况等影响。针对室内污染物的散发特点与分布,合理的对装饰装修引起的室内空气污染进行控制。     

温度对材料污染散发和室内空气甲醛浓度影响的分析

环境温度对装修引起的室内空气污染浓度有显著的影响。本文通过环境气候箱实验测试温度与甲醛污染释放率的关系,及对材料污染释放特性参数初始可散发浓度C_0、扩散系数D_m和分离系数K的影响;同时通过实际精装住宅工程的室内空气甲醛浓度测试,提出了室内空气甲醛浓度C与温度T的经验关系式,为建筑室内污染物控制设计和验收时考虑温度影响提供可行的计算方法。     

危险气体散发量对诱导风机影响的模拟研究

GB50019-2015条文6.3.12第四条指出:因建筑构造形成的有爆炸危险气体排出的死角处应设置导流设施。本文提出了用诱导风机进行导流的解决方法。文中对一个可能泄露危险气体的仓库进行了建模,先对理论计算与数值模拟的吻合性进行了分析,再对不同的危险气体散发量进行了数值模拟,分析了污染物浓度和空气龄。得出Fluent中k-εrealizable模型能较好地对射流进行模拟,在一定的换气次数下和污染物散发浓度范围内,污染物的散发量与稳态所得最终污染物浓度存在跟随性或无关性,但一定换气次数下,污染物不同的散发量对空气龄没有太大影响。同时也可看出,诱导通风对污染物的排出效果明显。     

确定建筑材料有害物散发量的三种传质模型

室内空气污染源散发量的确定是建立室内空气质量(IAQ)模型的重要步骤之一。目前研究建筑装饰材料和建筑涂料散发污染物的模型主要有经验模型和理论模型两类。经验模型简洁，但应用受到测试条件的限制，不具有普适性。基于传质理论而提出的理论模型目前研究较多，本文对研究建筑材料散发有害物的三个传质模型进行了评述。VB模型是一个简单的溶剂基室内涂料散发的总挥发性有机物(TVOC)的传质模型，低估了污染物的长期散发量。对流传质模型是基于界面平衡所导出的稳态模型，适用于固体和液体等材料的散发过程。Yang等提出的四层传质模型通常需与数值求解结合，计算较麻烦，但能较好地确定建筑材料散发挥发性有机物的散发量。     

民用建筑气密性对室内污染物浓度影响的实验研究

随着国家节能减排战略的实施,建筑物的气密性要求不断提高,而气密性的提高意味着换气次数的减少,意味着室内污染物积聚可能性增加。文章着重讨论民用建筑气密性对室内污染物浓度的影响。     

Experimental study on dehumidifier and regenerator of liquid desiccant cooling air conditioning system

A new type of air conditioning system, the liquid desiccant evaporation cooling air conditioning system (LDCS) is introduced in this paper. Desiccant evaporation cooling technology is environmental friendly and can be used to condition the indoor environment of buildings. Unlike conventional air conditioning systems, the system can be driven by low-grade heat sources such as solar energy and industrial waste heat with temperatures between 60 and 80 °C. In this paper, a LDCS, as well as a packed tower for the regenerator and dehumidifier is described. The effects of heating source temperature, air temperature and humidity, desiccant solution temperature and desiccant solution concentration on the rates of dehumidification and regeneration are discussed. Based on the experimental results, mass transfer coefficients of the regeneration process were experimentally obtained. The results showed that the mean mass transfer coefficient of the packing regenerator was 4 g/(m² s). In the experiments of dehumidification, it was found that there was maximal tower efficiency with the suitable inlet humidity of the indoor air. The effective curves of heating temperature on the outlet parameters of the regenerator were obtained. The relationships of regeneration mass transfer coefficient as a function of heating temperature and desiccant concentration are introduced.     

Gas-Phase Mass Transfer Model for Predicting Volatile Organic Compound (VOC) Emission Rates from Indoor Pollutant Sources

Abstract Analysis of the impact of sources on indoor pollutant concentrations and occupant exposure to indoor pollutants requires knowledge of the emission rates from the sources. Emission rates are often determined by chamber testing and the data from the chamber test are fitted to an empirical model. While the empirical models are useful, they do not provide information necessary to scale the chamber data to buildings nor do they provide information necessary to understand the processes controlling emissions. A mass transfer model for gas-phase-limited mass transfer is developed and described in this paper. Examples of sources with gas-phase-limited emissions are moth cakes, floor wax, stain, and varnish. The mass transfer model expresses the emission rate in terms of a mass transfer coefficient and a driving force. The mass transfer coefficient can be predicted from correlations of the Nusselt number and the Reynolds number. The experiments and data analysis used to develop the correlation are described in the paper. Experiments to verify the assumptions used to describe the driving force are also described. Suggestions for using data from existing empirical emission models to determine parameters for the mass transfer model are provided. The mass transfer model provides a significantly better fit to data from an indoor air quality test house than does the empirical first order decay model.     

Measurements and computations of ventilation efficiency and temperature efficiency in a ventilated room

In order to improve the indoor air quality in a room and to save energy, the air movement and contamination distributions in the room with ventilation have been studied experimentally and numerically. The experiment is carried out in a full-scale climate room with different air supply systems, heat gains from the venetian blinds and ventilation rates. The measurements concern room airflow patterns and air temperature, velocity and contamination concentration fields, etc. The airflow computer program PHOENICS and the cooling load program ACCURACY have been applied for the numerical simulations. PHOENICS solves the conservation equations of air mass, momentum, energy, concentration, kinetic energy and dissipation rate of kinetic energy. ACCURACY, which considers the influence of room air temperature distributions, is employed for the determination of cooling load, wall surface temperatures and convective heat transfer on room enclosure surfaces. These are the boundary conditions required by PHOENICS.The agreements between the computations and the measurements are good. The ventilation efficiency and temperature efficiency which are used for evaluation of indoor air quality and energy consumption are reported for each case. Additional application of these computations to annual energy analysis is also discussed.     

夏热冬冷地区高大公用建筑空调能耗特性分析

利用Energyplus软件对夏热冬冷地区高大公用建筑空调能耗进行模拟分析,通过正交试验法研究空调能耗受负荷影响因子的影响情况,给出的影响因子排序为设备负荷〉照明负荷〉人员密度〉室内设计温度〉新风量〉窗墙比〉外窗传热系数〉屋面传热系数〉遮阳系数〉外墙传热系数;进一步研究围护结构的影响因子与空调节能的关系,拟合得到节能率与围护结构影响因子间的回归方程,用于指导建筑空调节能设计及改造。     

基于PMV的空调外区进深确定

利用室内外温差和围护结构传热系数等参数,计算室内温度的变化,提出用表征人群对热环境平均投票值的PMV确定不同条件下空调房间内外分区界线。     

Study of the resistances to transfer of gaseous pollutant between material and indoor air

The main parameters which control the emission of volatile organic compounds between wall materials and indoor air were examined. A physically based model considers that the global emission phenomenon results from three elementary physical phenomena: diffusion through the boundary layer separating the wall from environment, diffusion within the porous network of the materials, and sorption of the gas molecules on the active sites of the materials. The pollutant transfer between porous material and air is therefore subjected to two complementary resistances and we identify first the resistance which controls the transfer. Then, we predict the global emission time constant from the mass transfer coefficient of convection and the thickness of the material. Experimental results from a small scale chamber are compared to predicted values in the case of acetone emission from chipboard in humid air and for high initial acetone concentration. Good agreement is obtained at the beginning of emission but an acetone retention effect by chipboard is observed, showing that it will be necessary to take into account the interactions of water vapor with materials and the pollutants to achieve accurate modeling of the material VOC emission process.     

Coupling of thermal mass and natural ventilation in buildings

The coupling of thermal mass and natural ventilation is important to passive building design. Thermal mass can be classified as external thermal mass and internal thermal mass. Due to great diurnal variation of ambient air temperature and solar radiation intensity, heat transfer through building envelopes, which is called external thermal mass, is a complex and unsteady process. Indoor furniture are internal thermal mass, affecting the indoor air temperature through the process of absorbing and releasing heat. In this paper, a heat balance model coupling the external and internal thermal mass, natural ventilation rate and indoor air temperature for naturally ventilated building is developed. In this model, the inner surface temperature of building envelopes is obtained based on the harmonic response method. The effect of external and internal thermal mass on indoor air temperature for six external walls is discussed of different configurations including lightweight and heavy structures with and without external/internal insulation. Based on this model, a simple tool is developed to estimate the indoor air temperature for certain external and internal thermal mass and to determine the internal thermal mass needed to maintain required indoor air temperature for certain external wall for naturally ventilated building.     

船舶围壁空气层自然对流对传热系数的影响分析

本文采用数值模拟软件对不同室内外温度条件下的船舶水平及垂直围壁稳态传热进行模拟计算。结果表明水平围壁在冬季和夏季的传热系数存在明显的差异,而且冬季的传热系数要比夏季的传热系数大的多,这主要是水平空气层在冬季的自然对流比夏季的自然对流强烈。垂直围壁冬季和夏季传热系数的差异很小。结果也表明同一季节的室内外温差的变化对围壁传热系数的影响均很小。因此在计算船舶空调负荷时,水平围壁传热系数取值应对冬季和夏季予以区分而垂直围壁的传热系数选取不需区分冬季和夏季。     

Influence of temperature on styrene emission from a vinyl ester resin thermoset composite material

Composite materials made with vinyl ester resins are lighter, stronger and corrosion resistant compared to most metals, and are increasingly being used as building materials and in public transportation. Styrene monomer is used as both a diluent and strengthener in the production of vinyl ester resin (VER) composites. Some researchers contend that free styrene in VER composites is available to diffuse out of the material into air, perhaps leading to adverse health effects via inhalation exposures in humans, yet there is no known data on styrene emissions from these materials in the literature. In this study, a typical VER composite made with resin containing 38% by weight styrene, reinforced with E-glass fiber and formed using a vacuum assisted resin transfer method was characterized for styrene emissions by environmental test chamber (ETC) methodology. Styrene concentrations in the ETC were measured over a temperature range of 10 to 50 °C. Initial evaporative styrene emissions increase with increasing temperature. There is a nearly linear relationship in the total mass of styrene emitted and emission factor as emissions increase with increasing temperature. Styrene emission factors appear to vary for different materials, which could indicate more complex processes or the influence of material physical properties on emission rates. These results can be used to validate and improve mass transfer emission models for the prediction of volatile organic compound concentrations in indoor environments.