Modeling Of Aerosol Particle Transportation In A Multi-zone Ventilated Room

With the rapid development of economics and urbanization in China, people's requirement for residential environment is no longer satisfied with the traditional demand of temperature, humidity or air quality. Now residents pay more attention to indoor air quality, and many modern buildings or rooms equipped mechanical ventilation systems for air exchanging between indoor and outdoor environment. Meanwhile, outdoor particles will probably enter rooms with intake airflow. So both experimental test and numerical simulation are carried out in the present paper to investigate and analyze the airflow and particle dispersion in a typical multi-zone ventilation room.Using the monitoring data of atmospheric aerosol particle concentration, the sparse gas-solid two-phase flow model is employed for the numerical simulation of the flow field in the ventilation room. The comparison between the numerical results and the experimental data in the literature indicates that the numerical model used in the present study is dependable for predicting air flow and aerosol transportation in the mechanical ventilation room.The simulation in the multi-zone ventilation room consists of two types of situation. First, there exists an initial particle concentration distribution in the room, and the effects of ventilation strategy on the particle concentration decay are investigated. Second, there's no particle pollutant indoor while aerosols enter the room with intake airflow from the inlet, and the effects of airflow pattern and partition opening size on the particle concentration dispersion in the two-zone ventilation room are simulated and analyzed. The numerical results show that the concentration discrepancy of large particles between ventilation room and closed room is not obvious, because coarse particles are mostly influenced by gravitational settling, while fine particles are mostly affected by the turbulent and diffusional dispersion.In addition, the numerical results indicate that airflow pattern can obviously influence the particle concentration distribution in the two-zone ventilation room. In the pattern of upside inlet, partition opening purifies the particles passed to zone-2, while in the pattern of downside inlet, partition opening doesn't purify the air because inlet and opening are both located in the downside of the room, but in this case, since the downside inlet is lower than respiratory plane, the concentration of coarse particles on the corresponding plane is less than fine particles. In zone-2, the downside outlet is propitious to vent coarse particles. By comparing particle concentration results in two different partition opening sizes, it indicates that the effect of small opening on indoor airflow and particle concentration is more obvious than large opening. The gravitational settling effect on the air in zone-1 is more efficient when decreasing the opening size.