Abstract:

Aerosols are tiny particulate matter suspended in the air that pose a serious health hazard to the human respiratory system. As a key transition space for indoor and outdoor air circulation, different design forms of public building entrances have a significant impact on the indoor air quality (IAQ). Through a literature review and field research, the entrance design forms of 36 public buildings in Hefei City were selected for feature extraction, and three types of typical entrance models, namely flushed, projected, and recessed entrances, were summarized. The air flow field and aerosol diffusion distribution model were established using numerical simulation of Computational Fluid Dynamics (CFD), and grid-independent validation of the simulation results was performed on a grid with different model precisions. The simulation data were compared and verified with on-site measured data, and the diffusion paths and distribution characteristics of indoor aerosols under three different types of entrance forms were explored. The results showed the following: 1) There was a significant correlation between indoor aerosol concentration and airflow. The higher the airflow rate, the lower the aerosol concentration; the smaller the airflow rate, the higher the aerosol concentration. 2) Vortices are easily formed in corner spaces or narrow spaces, and they lead to air stagnation and impede the diffusion of aerosols, and then lead to an increase in aerosol concentration in a given area. 3) The aerosol intake of the projected entrance was slightly smaller than that of the flushed entrance, accounting for 92.8% of that of the flushed entrance; however, its indoor aerosol residue was 23.6%, 7.3% higher than that of the flushed entrance. 4) The indoor aerosol residue was ranked in a descending order as follows: projected entrance (23.6%)>flushed entrance (16.3%)>recessed entrance (14.8%). The diffusion of aerosols at the recessed entrance was effectively suppressed in the case of natural ventilation, and the indoor aerosol residue was the lowest. It is recommended that a recessed entrance be used in the design and large-volume canopies be avoided to favor natural ventilation and improve the air quality of the building entrance/exit space. The results of this study provide a scientific basis for improving the IAQ and a reference for the design of entrance ventilation in public buildings.

Key words: public buildings, entrance forms, natural ventilation, aerosols, numerical simulations, air quality

摘要：

气溶胶是悬浮于空气中的微小颗粒物质，对人体呼吸系统健康具有严重危害。作为室内外空气流通的关键过渡空间，公共建筑入口的不同设计形式对室内空气质量（IAQ，Indoor Air Quality）产生显著影响。通过文献综述和实地调研，选取合肥市36座公共建筑的入口设计形式进行特征提取，归纳出了平入口、有雨棚的平入口和凹入口三类典型入口形式模型；利用计算流体力学（CFD）数值模拟方法建立了空气流场和气溶胶扩散分布模型，对模型的不同精度网格展开模拟结果的网格无关性验证；并在此基础上，利用现场实测数据进行了模拟数据的对比验证；探讨了三类不同入口形式下室内气溶胶的扩散路径和分布特征。结果表明：1）室内气溶胶浓度与空气流动之间存在显著的关联性。空气流动速率越大，气溶胶浓度越低；空气流动速率越小，气溶胶浓度越高；2）转角空间或狭小空间容易形成涡流，涡流会导致空气滞留，阻碍气溶胶扩散，进而导致局部区域的气溶胶浓度增加；3）有雨棚的平入口的气溶胶进入量略小于无雨棚平入口，占比无雨棚平入口的92.8%，但其室内气溶胶残留量为23.6%，高出无雨棚平入口7.3%；4）室内气溶胶残留量占比从高到低排列为：有雨棚的平入口(23.6%)>平入口 (16.3%)>凹入口 (14.8%)，凹入口在自然通风情况下气溶胶的扩散得到了有效抑制，室内气溶胶残留量最低。建议在设计中采用凹型入口，避免采用大体量雨棚，有利于自然通风，提升建筑出入口空间的空气质量。

关键词: 公共建筑, 出入口形式, 自然通风, 气溶胶, 数值模拟, 空气质量