Civil & Environmental Engineering Department, Stanford University, Stanford, California 94305, USA.
Environ Sci Technol. 2011 May 1;45(9):4016-22. doi: 10.1021/es103080p. Epub 2011 Apr 1.
For modeling exposure close to an indoor air pollution source, an isotropic turbulent diffusion coefficient is used to represent the average spread of emissions. However, its magnitude indoors has been difficult to assess experimentally due to limitations in the number of monitors available. We used 30-37 real-time monitors to simultaneously measure CO at different angles and distances from a continuous indoor point source. For 11 experiments involving two houses, with natural ventilation conditions ranging from <0.2 to >5 air changes per h, an eddy diffusion model was used to estimate the turbulent diffusion coefficients, which ranged from 0.001 to 0.013 m² s⁻¹. The model reproduced observed concentrations with reasonable accuracy over radial distances of 0.25-5.0 m. The air change rate, as measured using a SF₆ tracer gas release, showed a significant positive linear correlation with the air mixing rate, defined as the turbulent diffusion coefficient divided by a squared length scale representing the room size. The ability to estimate the indoor turbulent diffusion coefficient using two readily measurable parameters (air change rate and room dimensions) is useful for accurately modeling exposures in close proximity to an indoor pollution source.
为了模拟接近室内空气污染源的暴露情况，各向同性紊流扩散系数被用来表示排放物的平均扩散程度。然而，由于可用监测器的数量有限，室内的扩散系数很难通过实验来评估。我们使用 30-37 个实时监测器，同时测量从连续室内点源的不同角度和距离的 CO。对于涉及两栋房屋的 11 个实验，自然通风条件范围从<0.2 到>5 换气次数每小时，使用涡流扩散模型来估计紊流扩散系数，范围从 0.001 到 0.013 m² s⁻¹。该模型在 0.25-5.0 m 的径向距离内，以合理的精度再现了观测到的浓度。使用 SF₆示踪气体释放测量的空气交换率与空气混合率（定义为紊流扩散系数除以代表房间大小的平方长度尺度）呈显著正线性相关。使用两个易于测量的参数（空气交换率和房间尺寸）来估计室内紊流扩散系数的能力，对于准确模拟接近室内污染源的暴露情况非常有用。
