indoor air model

  • 文章类型: Journal Article
    光解作为户外空气化学引发剂的重要性已得到广泛认可,但其在室内化学加工中的作用往往被忽视。本文利用最近的实验数据修改了一个详细的化学模型,用它来研究玻璃类型的影响,人工室内照明,浑浊,一年中的时间和纬度对室内光解速率以及室内空气化学的影响。从LED切换到未覆盖的荧光灯管,预计室内羟基自由基浓度增加了约13%。然而,从透射波长超过380nm的室外光的玻璃移动到透射波长超过315nm的太阳光的玻璃导致预测的羟基自由基增加超过400%。对于我们研究的物种来说,包括臭氧,氮氧化物,亚硝酸,甲醛,和羟基自由基,后者对室内光解速率的变化最敏感。二氧化氮和甲醛的浓度基本不变,与室外交换和内部沉积控制其室内浓度。现代灯,如LED,与低透射眼镜一起,可能会减少室内光解的影响和潜在有害物种的产生。需要对不同室内空气混合物的健康影响进行研究以证实这一结论。
    The importance of photolysis as an initiator of air chemistry outdoors is widely recognized, but its role in chemical processing indoors is often ignored. This paper uses recent experimental data to modify a detailed chemical model, using it to investigate the impacts of glass type, artificial indoor lighting, cloudiness, time of year and latitude on indoor photolysis rates and hence indoor air chemistry. Switching from an LED to an uncovered fluorescent tube light increased predicted indoor hydroxyl radical concentrations by ~13%. However, moving from glass that transmitted outdoor light at wavelengths above 380 nm to one that transmitted sunlight above 315 nm led to an increase in predicted hydroxyl radicals of more than 400%. For our studied species, including ozone, nitrogen oxides, nitrous acid, formaldehyde, and hydroxyl radicals, the latter were most sensitive to changes in indoor photolysis rates. Concentrations of nitrogen dioxide and formaldehyde were largely invariant, with exchange with outdoors and internal deposition controlling their indoor concentrations. Modern lights such as LEDs, together with low transmission glasses, will likely reduce the effects of photolysis indoors and the production of potentially harmful species. Research is needed on the health effects of different indoor air mixtures to confirm this conclusion.
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  • 文章类型: Journal Article
    Most indoor air quality models reported in the literature are well-mixed models. A well-mixed model estimates the room average concentration of constituents from sources. It does not provide information on (1) how far and how fast the emitted chemicals travel in the indoor space? And (2) how the concentration changes as a function of distance from the emission source? We developed a distributed model, using computational fluid dynamics and thermodynamics principles, which allows for aerosol dispersion in an indoor space and includes evaporation and condensation of constituents in a multi-compound aerosol mixture. The distributed model can estimate the spatial and temporal variations of the concentration of individual constituents present in the emitted aerosol in vapor and particulate phases separately. Results from the model were compared with the published experimental data and were found to be in good agreement. A sensitivity analysis was performed to evaluate the impact of various parameters that affect the air level of the emitted constituents within an indoor space, including rate of emission, the rate of air exchange, etc. The model can also be used to estimate the level of second hand exposure in a confined space where e-vapor products (EVPs) are used.
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