Growth of organic films on indoor surfaces

We present a model for the growth of organic films on impermeable indoor surfaces. The model couples transport through a gas‐side boundary layer adjacent to the surface with equilibrium partitioning of semivolatile organic compounds (SVOCs) between the gas phase and the surface film. Model predictions indicate that film growth would primarily be influenced by the gas‐phase concentration of SVOCs with octanol‐air partitioning (K_oa) values in the approximate range 10≤log K_oa≤13. Within the relevant range, SVOCs with lower values will equilibrate with the surface film more rapidly. Over time, the film becomes relatively enriched in species with higher log K_oa values, while the proportion of gas‐phase SVOCs not in equilibrium with the film decreases. Given stable airborne SVOC concentrations, films grow at faster rates initially and then subsequently diminish to an almost steady growth rate. Once an SVOC is equilibrated with the film, its mass per unit film volume remains constant, while its mass per unit area increases in proportion to overall film thickness. The predictions of the conceptual model and its mathematical embodiment are generally consistent with results reported in the peer‐reviewed literature.     

Selective permeation of moisture and VOCs through polymer membranes used in total heat exchangers for indoor air ventilation

Fresh air ventilation is central to indoor environmental control. Total heat exchangers can be key equipment for energy conservation in ventilation. Membranes have been used for total heat exchangers for more than a decade. Much effort has been spent to achieve water vapor permeability of various membranes; however, relatively little attention has been paid to the selectivity of moisture compared with volatile organic compounds (VOCs) through such membranes. In this investigation, the most commonly used membranes, both hydrophilic and hydrophobic ones, are tested for their permeability for moisture and five VOCs (acetic acid, formaldehyde, acetaldehyde, toluene, and ethane). The selectivity of moisture vs. VOCs in these membranes is then evaluated. With a solution-diffusion model, the solubility and diffusivity of moisture and VOCs in these membranes are calculated. The resulting data could provide some reference for future material selection. PRACTICAL IMPLICATIONS: Total heat exchangers are important equipment for fresh air ventilation with energy conservation. However, their implications for indoor air quality in terms of volatile organic compound permeation have not been known. The data in this article help us to clarify the impacts on indoor VOC levels of membrane-based heat exchangers. Guidelines for material selection can be obtained for future use total heat exchangers for building ventilation.     

旋流通风方式下室内二氧化碳分布的实验研究

对8种旋流通风方式进行了实验测试,分别得到了各种通风方式下的速度场和污染物浓度场.结果表明,旋流通风方式用于改善气流组织和室内空气品质是经济可行的.     

居室热压自然通风应用探讨

采用风速法和示踪气体衰减法实测了某居室的自然通风量。得到了不同窗孔开度下的窗孔流量系数,给出了窗孔流量系数与窗孔开度的关系曲线,分析了室内外空气温差对窗孔流量系数的影响。     

自然通风在大空间建筑空调系统下室内热环境中应用的理论分析及实测研究

以上海市建筑科学研究院生态建筑示范基地为研究对象,对夏季由上部自然通风与下部空调系统共同形成的室内热环境进行了理论建模和现场测试研究.分析了不同工况下的温度分布,并探讨了自然通风在改善大空间建筑室内热环境中的有效利用及其优化途径.     

Real-time organic aerosol chemical speciation in the indoor environment using extractive electrospray ionization mass spectrometry

Understanding the sources and composition of organic aerosol (OA) in indoor environments requires rapid measurements, since many emissions and processes have short timescales. However, real-time molecular-level OA measurements have not been reported indoors. Here, we present quantitative measurements, at a time resolution of five seconds, of molecular ions corresponding to diverse aerosol-phase species, by applying extractive electrospray ionization mass spectrometry (EESI-MS) to indoor air analysis for the first time, as part of the highly instrumented HOMEChem field study. We demonstrate how the complex spectra of EESI-MS are screened in order to extract chemical information and investigate the possibility of interference from gas-phase semivolatile species. During experiments that simulated the Thanksgiving US holiday meal preparation, EESI-MS quantified multiple species, including fatty acids, carbohydrates, siloxanes, and phthalates. Intercomparisons with Aerosol Mass Spectrometer (AMS) and Scanning Mobility Particle Sizer suggest that EESI-MS quantified a large fraction of OA. Comparisons with FIGAERO-CIMS shows similar signal levels and good correlation, with a range of 100 for the relative sensitivities. Comparisons with SV-TAG for phthalates and with SV-TAG and AMS for total siloxanes also show strong correlation. EESI-MS observations can be used with gas-phase measurements to identify co-emitted gas- and aerosol-phase species, and this is demonstrated using complementary gas-phase PTR-MS observations.     

The effect of environmental and structural factors on indoor air quality of apartments in Korea

The indoor air quality (IAQ) was measured in newly built Korean apartments before and after occupancy in a survey of 158 residences in 24-apartment complexes nationwide. Factors that might affect pollutant concentration, such as temperature, humidity, housing size, and duration of occupancy, were analyzed in relation to the measured concentrations. Average pollutant levels were consistent with the Ministry of the Environment's recommended standards; however, pollutant levels in some apartments exceeded the current standards. We found that the concentrations of formaldehyde and toluene often exceeded the more stringent guidelines that will soon be enacted. Our results suggest that stronger countermeasures are therefore required to control these two chemicals. The results show that the pollution concentration was generally proportional to temperature and humidity, but that, in some cases, the concentration measurements were inversely proportional to these two factors, and in a few others the relationship between these factors was not clear. Indoor air pollution readings were highest in the 30-pyeong apartments, followed by 10-, and 20-pyeong residences. The pollutant concentrations decreased to about half of their initial levels after one year of occupancy, but the concentration of formaldehyde in indoor air persisted for a longer period. The duration of the apartment's occupancy affected indoor air pollutant concentrations more so than other factors such as temperature, humidity, and apartment size.     

多区域空气流动网络模型用于室内空气品质和通风模拟研究

介绍了用于研究建筑物内空气流动和污染物传播的多区域模拟软件CONTAMW，其使用条件和可以实现的模拟组合。着重分析了该模型在建筑通风、空内空气品质研究及防排烟领域的重要应用前景。     

自然通风作用下中庭建筑热环境的数值模拟

以上海地区一实际建筑为例,应用K-ε两方程湍流模型、零方程模型和数值模拟方法对双层玻璃幕墙中庭建筑内的温度场进行了模拟,计算了不同室内负荷下适用自然通风的时间。研究结果表明,自然通风在过渡季节能有效改善室内热环境,较好地满足人体热舒适要求。     

竖井型公路隧道自然通风过程的实验研究

采用量纲分析法得到竖井型公路隧道自然通风相似性准则.采用近似模拟的方法,在1:10缩尺模型隧道内进行了车辆单向运动实验,测试表明,进入自模区所要求的最小风速为0.33 m/s,达到最小风速要求的3种有效车况为f0.8v.1.6,f0.8v,2和f1.3vt2.通过量纲一化的测试数据与理论计算结果的比较,验证了准则的正确性.     

自然通风与节能舒适性分析

介绍了自然通风技术的基本原理与应用形式,从建筑物节能与舒适性两方面探讨了自然通风在建筑物中的应用,指出在自然通风的设计和应用过程中应综合考虑地理气候、建筑物结构和环境调节要求等因素,同时应加强相关技术的研究和开发。     

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.     

Real‐world volatile organic compound emission rates from seated adults and children for use in indoor air studies

Human beings emit many volatile organic compounds (VOCs) of both endogenous (internally produced) and exogenous (external source) origin. Here we present real‐world emission rates of volatile organic compounds from cinema audiences (50‐230 people) as a function of time in multiple screenings of three films. The cinema location and film selection allowed high‐frequency measurement of human‐emitted VOCs within a room flushed at a known rate so that emissions rates could be calculated for both adults and children. Gas‐phase emission rates are analyzed as a function of time of day, variability during the film, and age of viewer. The average emission rates of CO₂, acetone, and isoprene were lower (by a factor of ~1.2‐1.4) for children under twelve compared to adults while for acetaldehyde emission rates were equivalent. Molecules influenced by exogenous sources such as decamethylcyclopentasiloxanes and methanol tended to decrease over the course of day and then rise for late evening screenings. These results represent average emission rates of people under real‐world conditions and can be used in indoor air quality assessments and building design. Averaging over a large number of people generates emission rates that are less susceptible to individual behaviors.     

Preventing the entry of outdoor particles with the indoor positive pressure control method: Analysis of influencing factors and cost

Maintaining positive pressure indoors with a mechanical ventilation system is a popular control method for preventing the entry of outdoor airborne particles. This paper analyzes the factors which affect the satisfied superfluous airflow rates of positive pressure control. Through modeling a large amount of cases with a validated model, the factors, e.g. temperature difference, outdoor wind velocity, effective air leakage gaps in the envelopes, the area of the air leakage and the room, were analyzed. Based on the theoretical model, a correlating equation to calculate the satisfied superfluous airflow rate was established by multiple full quadratic regressions. The correlating equation is simple for engineers or designers to use to determine the satisfied superfluous airflow rate. This paper also aims to find which method, pressure control or indoor air cleaning, costs less to prevent the same amount of outdoor-originated particles from entering indoor environments. Generally speaking, indoor air cleaning control method requires less supply airflow rate than positive pressure control method for reducing the concentration of indoor particles with outdoor origin. An exception for this is a situation with a very low indoor/outdoor particle concentration (I/O ratio) requirement.     

示踪气体浓度衰减法在民用建筑自然通风研究中的应用

用示踪气体浓度衰减法对某会议室的自然通风作了实测研究，分析了影响换气次数的各种因素、示踪气体浓度衰法的有效性及其正确应用。揭示出不同的房间布置及不同的门窗开启民政部对换气次数有很大影响，而示踪气体浓度衰减法是对此进行实验研究的有效手段。     

岳阳某地下商场自然通风的测定与分析

该商场自然通风气流方向始终是由南向北，不受室外风向变化的影响。通过测试分析，认为要取得良好的自然通风效果，设置通风口时必须考虑周边建筑和室外风向的影响，合理利用地形地物。     

热车间内有局部排风时自然通风量的计算

分析了现有手册中车间内有局部排风时消除车间余热所需自然通风量计算公式中存在的问题，通过车间内的热平衡和空气平衡，推出了合理的计算公式，并进行了探讨。     

Characterization of indoor sources of fine and ultrafine particles: a study conducted in a full-scale chamber

Humans and their activities are known to generate considerable amounts of particulate matter indoors. Some of the activities are cooking, smoking and cleaning. In this study 13 different particle sources were for the first time examined in a 32 m3 full-scale chamber with an air change rate of 1.7 +/- 0.1/h. Two different instruments, a condensation particle counter (CPC) and an optical particle counter (OPC) were used to quantitatively determine ultrafine and fine particle emissions, respectively. The CPC measures particles from 0.02 microm to larger than 1.0 microm. The OPC was adjusted to measure particle concentrations in eight fractions between 0.3 and 1.0 microm. The sources were cigarette side-stream smoke, pure wax candles, scented candles, a vacuum cleaner, an air-freshener spray, a flat iron (with and without steam) on a cotton sheet, electric radiators, an electric stove, a gas stove, and frying meat. The cigarette burning, frying meat, air freshener spray and gas stove showed a particle size distribution that changed over time towards larger particles. In most of the experiments the maximum concentration was reached within a few minutes. Typically, the increase of the particle concentration immediately after activation of the source was more rapid than the decay of the concentration observed after deactivation of the source. The highest observed concentration of ultrafine particles was approximately 241,000 particles/cm3 and originated from the combustion of pure wax candles. The weakest generation of ultrafine particles (1.17 x 10(7) particles per second) was observed when ironing without steam on a cotton sheet, which resulted in a concentration of 550 particles/cm3 in the chamber air. The highest generation rate (1.47 x 10(10) particles per second) was observed in the radiator test. PRACTICAL IMPLICATIONS: Humans and their activities are known to generate substantial amounts of particulate matter indoors and potentially they can have a strong influence on short-term exposure. In this study a quantitative determination of the emissions of fine and ultrafine particles from different indoor sources was performed. The aim is a better understanding of the origin and fate of indoor particles. The results may be useful for Indoor Air Quality models.     

有关防排烟系统规范条文疑难解析

提出了有关防排烟系统规范中几项难以把握的条文,结合工作实际给出了相关的处理对策。